120 results on '"Dong-Ho Lee"'
Search Results
2. Post-neoadjuvant treatment pancreatic cancer resectability and outcome prediction using CT, 18F-FDG PET/MRI and CA 19–9
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Jeongin Yoo, Jeong Min Lee, Ijin Joo, Dong Ho Lee, Jeong Hee Yoon, Mi Hye Yu, Jin-Young Jang, and Sang Hyub Lee
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Oncology ,Radiological and Ultrasound Technology ,Radiology, Nuclear Medicine and imaging ,General Medicine - Abstract
Background CT prediction of resectability and prognosis following neoadjuvant treatment (NAT) in patients with pancreatic ductal adenocarcinoma (PDAC) remains challenging. This study aims to determine whether addition of 18F-fluorodeoxyglucose (FDG) postiron emission tomography (PET)/MRI and carbohydrate antigen (CA) 19–9 to contrast-enhanced CT (CECT) can improve accuracy of predicting resectability compared to CECT alone and predict prognosis in PDAC patients after NAT. Methods In this retrospective study, 120 PDAC patients (65 women; mean age, 66.7 years [standard deviation, 8.4]) underwent CECT, PET/MRI, and CA 19–9 examinations after NAT between January 2013 and June 2021. Three board-certified radiologists independently rated the overall resectability on a 5-point scale (score 5, definitely resectable) in three sessions (session 1, CECT; 2, CECT plus PET/MRI─no FDG avidity and no diffusion restriction at tumor-vessel contact indicated modification of CECT scores to ≥ 3; 3, CECT plus PET plus CA 19–9─no FDG avidity at tumor-vessel contact and normalized CA 19–9 indicated modification of CECT scores to ≥ 3). Jackknife free-response receiver operating characteristic method and generalized estimating equations were used to compare pooled area under the curve (AUC), sensitivity, and specificity of three sessions. Predictors for recurrence-free survival (RFS) were assessed using Cox regression analyses. Results Each session showed different pooled AUC (session 1 vs. 2 vs. 3, 0.853 vs. 0.873 vs. 0.874, p = 0.026), sensitivity (66.2% [137/207] vs. 86.0% [178/207] vs. 84.5% [175/207], p p = 0.048). According to pairwise comparison, specificity of CECT plus PET/MRI was lower than that of CECT alone (adjusted p = 0.042), while there was no significant difference in specificity between CECT alone and CECT plus PET plus CA 19–9 (adjusted p = 0.081). Twenty-eight of 69 patients (40.6%) with R0 resection experienced tumor recurrence (mean follow-up, 18.0 months). FDG avidity at tumor-vessel contact on post-NAT PET (HR = 4.37, p = 0.033) and pathologically confirmed vascular invasion (HR = 5.36, p = 0.004) predicted RFS. Conclusion Combination of CECT, PET and CA 19–9 increased area under the curve and sensitivity for determining resectability, compared to CECT alone, without compromising the specificity. Furthermore, 18F-FDG avidity at tumor-vessel contact on post-NAT PET predicted RFS.
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- 2023
3. High-resolution pancreatic computed tomography for assessing pancreatic ductal adenocarcinoma resectability: a multicenter prospective study
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Dong Ho Lee, Hong Il Ha, Jin-Young Jang, Jung Woo Lee, Jin-Young Choi, Seungmin Bang, Chang Hee Lee, Wan Bae Kim, Seung Soo Lee, Song Cheol Kim, Bo-Kyeong Kang, and Jeong Min Lee
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Radiology, Nuclear Medicine and imaging ,General Medicine - Published
- 2023
4. Improvement and Field Testing of Tuned Mass Piezo-Damper with Electricity-Generating Capacity
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Jinkyo F. Choo, Dong-Ho Ha, Dong-Ho Lee, and Eun-San Cho
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Civil and Structural Engineering - Published
- 2022
5. The medial window technique as a salvage method to insert C2 pedicle screw in the case of a high-riding vertebral artery or narrow pedicle: a technical note and case series
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Dong-Ho Lee, Sehan Park, Jae Hwan Cho, Chang Ju Hwang, Hyung Rae Lee, Sang Yun Seok, and Choon Sung Lee
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Neck Pain ,Spinal Fusion ,Pedicle Screws ,Research Design ,Cervical Vertebrae ,Humans ,Orthopedics and Sports Medicine ,Surgery ,Vertebral Artery ,Retrospective Studies - Abstract
To describe the safety and feasibility of C2 medial window screw (C2MWS) as an alternative salvage method for C2 pedicle screws in cases of high-riding vertebral artery (HRVA) or narrow pedicle.The C2MWS technique involves screw insertion by intentionally breaching the medial cortex of the pedicle to avoid vertebral artery injury. Twelve patients who underwent C2 screw insertion via the C2MWS were retrospectively reviewed. C2MWS was indicated in cases of high-riding vertebral artery (HRVA) or narrow pedicle (pedicle width ≤ 4 mm). The width of the canal breach by screw, vertebral artery groove (VAG) breach, solid fusion, neck pain visual analogue scale (VAS) score, and Japanese Orthopedic Association (JOA) score were assessed as outcome measurements.C2MWS was indicated due to both HRVA and narrow pedicle for 11 screws, narrow pedicle for one screw, and HRVA for two screws. No screw VAG breach or vertebral artery injury was noted postoperatively. The mean width of canal breach was 2.9 ± 1.3 mm. There were no cases demonstrating neurologic deterioration, and 11 patients (91.7%) demonstrated solid fusion at 1-year follow-up. Furthermore, neck pain VAS and JOA scores significantly improved after the surgery.The C2MWS technique can provide 3-column fixation while reliably avoiding VA injury. C2MWS could be considered as a salvage alternative method when the insertion of C2 pedicle screw is complicated by HRVA or a narrow pedicle, while there is a need to provide firmer fixation strength than that provided by pars or translaminar screws.
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- 2022
6. Correction: Optimization of the clinically approved Mg-Zn alloy system through the addition of Ca
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Hyung-Jin Roh, Jaeho Park, Sun-Hee Lee, Do-Hyang Kim, Gwang-Chul Lee, Hojeong Jeon, Minseong Chae, Kang-Sik Lee, Jeong-Yun Sun, Dong-Ho Lee, Hyung-Seop Han, and Yu-Chan Kim
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Biomaterials ,Biomedical Engineering ,Ceramics and Composites ,Medicine (miscellaneous) - Published
- 2022
7. Diagnostic performance of ultrasound attenuation imaging for assessing low-grade hepatic steatosis
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Jong Keon Jang, So Yeon Kim, In Woon Yoo, Dong Ho Lee, Hyo Jeong Kang, and Young Bum Cho
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medicine.medical_specialty ,Biopsy ,medicine.medical_treatment ,Liver transplantation ,Severity of Illness Index ,Gastroenterology ,Non-alcoholic Fatty Liver Disease ,Internal medicine ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,Ultrasonography ,medicine.diagnostic_test ,business.industry ,Fatty liver ,Ultrasound ,General Medicine ,medicine.disease ,Fatty Liver ,Liver ,ROC Curve ,Attenuation coefficient ,Liver biopsy ,Elasticity Imaging Techniques ,Radiology ,Steatosis ,business ,Transient elastography - Abstract
To investigate the diagnostic performance of attenuation imaging (ATI) for the assessment of low-grade hepatic steatosis using liver biopsy as the reference standard. The study included 57 potential donor candidates for living liver transplantation who underwent ATI, transient elastography (TE), and liver biopsy for evaluation of hepatic steatosis between February 2020 and April 2020. The attenuation coefficient (AC) from ATI and the controlled attenuation parameter (CAP) from TE were measured for each participant in a random and blind manner. The histologic hepatic fat fraction (HFF) was graded (S0, 66%). The accuracy of ATI for diagnosing hepatic steatosis was compared with that of CAP using ROC analysis. Correlations between AC and HFF were evaluated, and factors affecting AC were determined by linear regression analysis. The median HFF was 3% (range: 0–35%), with 31 (54.4%), 24 (42.0%), and 2 (3.5%) participants being graded as S0, S1, and S2, respectively. The AUCs for the ROCs of AC and CAP for the detection of hepatic steatosis were 0.808 (95% CI: 0.682–0.900) and 0.829 (95% CI: 0.706–0.916), respectively, with the difference not being statistically significant (p = 0.762). AC showed 61.5% of sensitivity and 90.3% of specificity. AC was positively correlated with HFF (p
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- 2021
8. Comparison of endoscopic treatments for small gastric adenomas
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Jae Ho Cho, Cheol Min Shin, Nayoung Kim, Dong Ho Lee, Young Soo Park, and Hyuk Yoon
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Adenoma ,medicine.medical_specialty ,Endoscopic Mucosal Resection ,Endoscopic mucosal resection ,Adenomatous Polyps ,Stomach Neoplasms ,health services administration ,Internal medicine ,Humans ,Medicine ,Intestinal Mucosa ,Adverse effect ,Retrospective Studies ,business.industry ,Stomach ,Histology ,Hepatology ,medicine.disease ,Surgery ,Treatment Outcome ,medicine.anatomical_structure ,Propensity score matching ,Neoplasm Recurrence, Local ,business ,Abdominal surgery - Abstract
Gastric adenomas can be successfully treated with endoscopic resection, including endoscopic submucosal dissection (ESD) and endoscopic mucosal resection (EMR). The aim of this study was to evaluate and compare the efficacy of ESD and EMR with circumferential precutting (EMR-P) in the treatment of small gastric adenomas. This study included 1014 gastric adenomas ≤ 15 mm in diameter treated with ESD or EMR-P from 2012 to 2019, retrospectively. Propensity score matching between the ESD and EMR-P groups (1:1 to 3:1) was performed according to age, sex, tumor size, tumor location (upper, middle, and lower thirds), morphology, and preprocedural histology. The procedure time and the rates of en bloc resection, complete resection, adverse events, and local recurrence were compared between the two groups. After propensity score matching, 478 lesions (ESD: 295, EMR-P: 183) were analyzed. The rates of en bloc resection (94.9% vs. 93.4%, p = 0.498), complete resection (93.6% vs. 90.2%, p = 0.177), bleeding (8.1% vs. 3.8%, p = 0.063), and local recurrence (0.0% vs. 1.4%, p = 0.185) did not significantly differ between the two groups. The procedure time was significantly longer for ESD than for EMR-P (p
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- 2021
9. Collinsella acetigenes sp. nov., an Anaerobic Actinobacterium Isolated from Human Feces, and Emended Description of the Genus Collinsella and Collinsella aerofaciens
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Seoung Woo Ryu, Se Won Kang, Han Sol Kim, Jam-Eon Park, Dong Ho Lee, Keun Chul Lee, Seung-Hwan Park, Byung-Yong Kim, Seung-Hyeon Choi, Ji-Sun Kim, Seung Yeob Yu, Je Hee Lee, Hyuk Yoon, Min Kuk Suh, Kook-Il Han, Mi Kyung Eom, Byeong Seob Oh, Jung-Sook Lee, and Ju Huck Lee
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biology ,Accession number (library science) ,Sequence analysis ,General Medicine ,Ribosomal RNA ,biology.organism_classification ,16S ribosomal RNA ,Applied Microbiology and Biotechnology ,Microbiology ,Actinobacteria ,chemistry.chemical_compound ,Collinsella aerofaciens ,chemistry ,Diaminopimelic acid ,Collinsella - Abstract
A novel actinobacterial strain, Gram-positive, anaerobic, non-motile, and rod-shaped, designated KGMB02528T, was isolated from healthy human feces. Cells of strain KGMB02528T grew optimally at pH 7.0 and 37 °C and in the presence of 0% (w/v) NaCl. Based on 16S rRNA gene sequence similarity, strain KGMB04489T belonged to the genus Collinsella and was most closely related to Collinsella aerofaciens DSM 17552T (95.8%). The DNA G + C content was 58.0 mol%. The major cellular fatty acids (> 10%) were C16:0 DMA, C16:0 ALDE, C14:0 DMA, and C12:0. The predominant end product of fermentation was acetic acid. The cell wall peptidoglycan of strain KGMB02528T contained alanine, glutamic acid, and lysine, while diaminopimelic acid was not detected. The polar lipids were composed of two unidentified phospholipids and unidentified nine glycolipids. Based on the phenotypic, chemotaxonomic, and phylogenetic properties, strain KGMB02528T represents a novel species of the genus Collinsella, for which the name Collinsella acetigenes sp. nov. is proposed. The type strain is Collinsella acetigenes KGMB02528T (= KCTC 15847T = CCUG 73987T). The description of the genus Collinsella is emended to accommodate the new species. The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of Collinsella acetigenes KGMB02528T is MT117838. The whole-genome shotgun BioProject number is PRJNA623694 with the accession number JABBCP000000000.
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- 2021
10. The Difference of Endoscopic and Histologic Improvements of Atrophic Gastritis and Intestinal Metaplasia After Helicobacter pylori Eradication
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Cheol Min Shin, Hye Seung Lee, Yong-Hoon Choi, Young Soo Park, Young Jae Hwang, Hyuk Yoon, Dong Ho Lee, and Nayoung Kim
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medicine.medical_specialty ,medicine.diagnostic_test ,biology ,Physiology ,Atrophic gastritis ,business.industry ,Gastroenterology ,Cancer ,Intestinal metaplasia ,Histology ,macromolecular substances ,Helicobacter pylori ,Hepatology ,medicine.disease ,biology.organism_classification ,Endoscopy ,Internal medicine ,medicine ,business ,Antrum - Abstract
Helicobacter pylori (H. pylori) is an important risk factor of atrophic gastritis (AG), intestinal metaplasia (IM), and gastric cancer (GC). However, no report to date has described the endoscopic improvement of AG and IM after H. pylori eradication. Thus, the aim of this study was to evaluate the improvement of AG and IM after H. pylori eradication using endoscopic and histologic analyses. A total of 380 subjects were prospectively enrolled for up to 12 years and grouped by their H. pylori infection status: negative, non-eradicated, and eradicated. Endoscopic and histologic analyses of AG and IM were performed in the antrum and the corpus, by annual follow-up endoscopy. Endoscopic AG and IM in the antrum and corpus in the eradicated group improved compared to that in the non-eradicated group (AG, P = 0.002 and P = 0.005; IM, P = 0.038 and P = 0.048, respectively). Histologic AG and IM in the antrum and corpus in the eradicated group also improved compared to that in the non-eradicated group (all P
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- 2021
11. Utility of Real-time CT/MRI-US Automatic Fusion System Based on Vascular Matching in Percutaneous Radiofrequency Ablation for Hepatocellular Carcinomas: A Prospective Study
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Dong Ho Lee, Seungchul Han, Jeong Min Lee, Won Chang, and Jeong Hee Yoon
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medicine.medical_specialty ,Image fusion ,Percutaneous ,medicine.diagnostic_test ,business.industry ,Radiofrequency ablation ,Ultrasound ,Image registration ,Magnetic resonance imaging ,medicine.disease ,law.invention ,law ,Hepatocellular carcinoma ,Medicine ,Radiology, Nuclear Medicine and imaging ,Radiology ,Cardiology and Cardiovascular Medicine ,business ,Prospective cohort study - Abstract
To prospectively evaluate the technical success rate of real-time computed tomography/magnetic resonance imaging and ultrasound (CT/MRI-US) automatic fusion system and the long-term therapeutic efficacy of radiofrequency ablation (RFA) guided by automatic fusion in hepatocellular carcinoma (HCC) patients. 139 patients with 151 HCCs were prospectively enrolled for RFA guided by an automatic CT/MRI-US fusion system (PercuNav system, Philips, the Netherlands). Automatic fusion imaging, based on vascular segmentation and registration, was performed by sonographic sweeping at the intercostal plane. The fusion quality, tumor localization confidence and technical feasibility were recorded before and after fusion using a scoring system. Technical success rate of the RFA procedure and local tumor progression (LTP) were assessed during follow-up. Analysis of technical success and LTP was performed using generalized estimating equations and Cox proportional hazard regression analysis. The success rate of the fusion system was 82.7% (115/139) per patient. The mean sonographic scan time for fusion was 154.4 ± 108.4 s. In patients with successful fusion, the score indicating tumor localization confidence (2.2 ± 0.8 vs. 2.7 ± 0.9) and technical feasibility (2.6 ± 0.8 vs. 3.4 ± 0.7) increased after fusion (p
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- 2021
12. In-depth characterization of non-human sialic acid (Neu5Gc) in human serum using label-free ZIC-HILIC/MRM-MS
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Dong Ho Lee, Hyun Joo An, Jaehan Kim, Hee Jin Jeong, Myung Jin Oh, Unyong Kim, Nari Seo, Jaekyoung Ko, Yoon Jin Choi, and Daum Lee
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Glycan ,biology ,Immunogenicity ,Selective isolation ,Biochemistry ,Analytical Chemistry ,Sialic acid ,Highly sensitive ,Zic hilic ,chemistry.chemical_compound ,chemistry ,biology.protein ,Free form ,Label free - Abstract
Sialic acid Neu5Gc, a non-human glycan, is recognized as a new harmful substance that can cause vascular disease and cancer. Humans are unable to synthesize Neu5Gc due to a genetic defect that converts Neu5Ac to Neu5Gc, but Neu5Gc is often observed in human biological samples. Therefore, the demand for accurately measuring the amount of Neu5Gc present in human blood or tissues is rapidly increasing, but there is still no method to reliably quantify trace amounts of a non-human sugar. In particular, selective isolation and detection of Neu5Gc from human serum is analytically challenging due to the presence of excess sialic acid Neu5Ac, which has physicochemical properties very similar to Neu5Gc. Herein, we developed the label-free approach based on ZIC-HILIC/MRM-MS that can enrich sialic acids released from human serum and simultaneously monitor Neu5Ac and Neu5Gc. The combination of complete separation of Neu5Gc from abundant Neu5Ac by hydrophilic and electrostatic interactions with selective monitoring of structure-specific cross-ring cleavage ions generated by negative CID-MS/MS was remarkably effective for quantification of Neu5Ac and Neu5Gc at the femtomole level. Indeed, we were able to successfully determine the absolute quantitation of Neu5Gc from 30 healthy donors in the range of 3.336 ± 1.252 pg/μL (mean ± SD), 10,000 times lower than Neu5Ac. In particular, analysis of sialic acids in protein-free serum revealed that both Neu5Ac and Neu5G are mostly bound to proteins and/or lipids, but not in free form. In addition, the correlation between expression level of Neu5Gc and biological factors such as BMI, age, and sex was investigated. This method can be widely used in studies requiring sialic acid-related measurements such as disease diagnosis or prediction of immunogenicity in biopharmaceuticals as it is both fast and highly sensitive.
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- 2021
13. Bacteroides humanifaecis sp. nov., isolated from faeces of healthy Korean
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Han Sol Kim, Ji-Sun Kim, Min Kuk Suh, Mi Kyung Eom, Ju Huck Lee, Seung-Hwan Park, Se Won Kang, Dong Ho Lee, Hyuk Yoon, Je Hee Lee, and Jung-Sook Lee
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DNA, Bacterial ,Fatty Acids ,Vitamin K 2 ,Sequence Analysis, DNA ,General Medicine ,Biochemistry ,Microbiology ,Bacterial Typing Techniques ,Feces ,RNA, Ribosomal, 16S ,Republic of Korea ,Genetics ,Bacteroides ,Humans ,Molecular Biology ,Phylogeny - Abstract
Two obligately anaerobic, Gram-stain-negative, non-motile, non-spore-forming and short rod shaped bacteria, designated KGMB07931
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- 2022
14. Added value of [18F]FDG PET/MRI over MDCT alone in the staging of recurrent gastric cancer
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Ieun Yoon, Se Hyung Kim, Jeongin Yoo, Jae Seok Bae, and Dong Ho Lee
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medicine.medical_specialty ,Receiver operating characteristic ,medicine.diagnostic_test ,business.industry ,Stomach ,Ultrasound ,Magnetic resonance imaging ,Interventional radiology ,General Medicine ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,McNemar's test ,medicine.anatomical_structure ,Positron emission tomography ,030220 oncology & carcinogenesis ,medicine ,Radiology, Nuclear Medicine and imaging ,Radiology ,business ,Neuroradiology - Abstract
To investigate whether 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) positron emission tomography/magnetic resonance imaging (PET/MRI) can improve the diagnostic performance of TNM staging and help in making an accurate decision regarding resectability in patients with recurrent gastric cancer compared to multi-detector computed tomography (MDCT). Fifty patients with histologically (n = 31) or clinically (n = 19) confirmed recurrent gastric cancer underwent both MDCT and [18F]FDG PET/MRI. Two radiologists independently assessed TNM staging using MDCT with and without [18F]FDG PET/MRI and scored resectability using a 5-point confidence scale. Diagnostic performance as assessed by radiologists was compared using McNemar’s test and receiver operating characteristic curve analysis. Of the 50 patients, pathologic T and N staging was available in seven and six patients, respectively. Diagnostic accuracies for T and N staging were not significantly different between MDCT with and without [18F]FDG PET/MRI for both reviewers (p > 0.05). However, for M staging, diagnostic accuracy was significantly improved when 18F-FDG PET/MRI was added to MDCT alone (68.0% [34/50] to 90.0% [45/50] for reviewer 1 [p = 0.001] and 66.0% [33/50] to 96.0% [46/50] for reviewer 2 [p < 0.001]). Regarding the resectability of recurrent gastric cancers, the addition of [18F]FDG PET/MRI increased the area under the curve values for both reviewers (from 0.860 to 0.989 for reviewer 1 and from 0.778 to 0.898 for reviewer 2), with a statistical significance for reviewer 2 (p = 0.002). Compared to MDCT alone, MDCT plus [18F]FDG PET/MRI can improve the diagnostic accuracy for evaluating preoperative M staging as well as resectability for recurrent gastric cancers. • [ 18 F]FDG PET/MRI can improve diagnostic accuracy for preoperative M staging in patients with recurrent gastric cancers. • [ 18 F]FDG PET/MRI can improve diagnostic accuracy for determining resectability in patients with recurrent gastric cancers. • [ 18 F]FDG PET/MRI can provide critical clues for management options for recurrent gastric cancers.
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- 2021
15. Preoperative assessment of the resectability of pancreatic ductal adenocarcinoma on CT according to the NCCN Guidelines focusing on SMA/SMV branch invasion
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Haeryoung Kim, Hongbeom Kim, Wooil Kwon, Siwon Jang, Dong Ho Lee, Sae Jin Park, Kyoung Bun Lee, Jin-Young Jang, and Joon Koo Han
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medicine.medical_specialty ,Pancreatic ductal adenocarcinoma ,Tumor size ,medicine.diagnostic_test ,business.industry ,Interventional radiology ,General Medicine ,Guideline ,medicine.disease ,humanities ,030218 nuclear medicine & medical imaging ,Resection ,03 medical and health sciences ,0302 clinical medicine ,medicine.anatomical_structure ,030220 oncology & carcinogenesis ,medicine ,Adenocarcinoma ,Radiology, Nuclear Medicine and imaging ,In patient ,Radiology ,Pancreas ,business - Abstract
For patients with pancreatic adenocarcinoma (PAC), adequate determination of disease extent is critical for optimal management. We aimed to evaluate diagnostic accuracy of CT in determining the resectability of PAC based on 2020 NCCN Guidelines. We retrospectively enrolled 368 consecutive patients who underwent upfront surgery for PAC and preoperative pancreas protocol CT from January 2012 to December 2017. The resectability of PAC was assessed based on 2020 NCCN Guidelines and compared to 2017 NCCN Guidelines using chi-square tests. Overall survival (OS) was estimated using the Kaplan-Meier method and compared using log-rank test. R0 resection–associated factors were identified using logistic regression analysis. R0 rates were 80.8% (189/234), 67% (71/106), and 10.7% (3/28) for resectable, borderline resectable, and unresectable PAC according to 2020 NCCN Guidelines, respectively (p
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- 2021
16. Novel Approach to Improve the Optical Performance by Machining Process Without Surface Finishing
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Hong-Seung Kim, Dong-Ho Lee, Ji Yong Bae, Geonhee Kim, Dong Uk Kim, Kye-Sung Lee, Minwoo Jeon, June Gyu Park, Woo-Jong Yeo, Ki Soo Chang, and I Jong Kim
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Materials science ,Waviness ,Renewable Energy, Sustainability and the Environment ,business.industry ,Mechanical Engineering ,Optical engineering ,Physics::Optics ,Polishing ,Bragg's law ,02 engineering and technology ,Diamond turning ,021001 nanoscience & nanotechnology ,01 natural sciences ,Industrial and Manufacturing Engineering ,010309 optics ,Optics ,Machining ,Management of Technology and Innovation ,0103 physical sciences ,General Materials Science ,0210 nano-technology ,business ,Beam (structure) ,Surface finishing - Abstract
With the increase in dimensions of optical elements in addition to ever rising demand for aspherical optics, the millimeter-scale periodic waviness that is naturally produced by machining (such as diamond turning) process in precision optical engineering has been one of the most crucial issues in the development of high surface quality optical elements. Even an extremely small waviness can affect the laser beam profile significantly through interference caused by Bragg scattering. This paper presents a novel method for improving a laser beam profile by utilizing the characteristics of Bragg scattering without requiring established final surface finishing processes such as optical polishing. By engraving an artificial periodic structure with a period of a few hundred microns, the Bragg scattering angle that influences the formation of interference fringes in the laser beam profile was drastically enlarged. Consequently, the quality of the beam profile was improved at a propagation distance where the 0th and 1st (− 1st) order beam modes are spatially separated, only by diamond turning machining without the surface finishing process. In addition, this approach represents an important contribution to green technology, which seeks energy saving and waste reduction in the optical surface manufacturing process.
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- 2021
17. Different effects of p53 protein overexpression on the survival of gastric cancer patients according to Lauren histologic classification: a retrospective study
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Nayoung Kim, Sang Hoon Ahn, Young Soo Park, Do Joong Park, Jin Won Kim, Hyuk Yoon, Hyung Ho Kim, Hye Seung Lee, Keun Wook Lee, Young Hoon Kim, Ji Won Kim, Ji Hoon Park, Won Chang, Yoon Jin Lee, Dong Ho Lee, Won Seok Kim, Cheol Min Shin, Kyoung Ho Lee, Young Suk Park, Yong-Hoon Choi, and Ki Wook Kim
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Cancer Research ,medicine.medical_specialty ,Tumor suppressor gene ,business.industry ,Hazard ratio ,Gastroenterology ,Cancer ,General Medicine ,medicine.disease ,Early Gastric Cancer ,03 medical and health sciences ,0302 clinical medicine ,Oncology ,Surgical oncology ,030220 oncology & carcinogenesis ,Internal medicine ,Medicine ,Immunohistochemistry ,030211 gastroenterology & hepatology ,Stage (cooking) ,business ,Survival rate - Abstract
Inactivation of TP53, a tumor suppressor gene, is associated with the development of several malignancies, including gastric cancer (GC). The present study aimed to evaluate the correlation between the overexpression of p53 and survival in different Lauren-type GCs. From May 2003 to December 2019, 3608 GC patients treated endoscopically or surgically at the Seoul National University Bundang Hospital were enrolled for the study. Immunohistochemical staining for p53 was performed on all endoscopic and surgical gastric specimens. Clinicopathologic characteristics with Lauren classification, survival rate, and cancer recurrence were analyzed according to p53 overexpression. Among 3608 GC patients, p53 overexpression was seen in 1334 patients (37%). p53 overexpression was associated with lower depth of invasion (P = 0.026) and Early gastric cancer (P = 0.044) in intestinal-type GC, and with advanced TNM stage (P
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- 2021
18. 2D shear wave elastography is better than transient elastography in predicting post-hepatectomy complication after resection
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Jae Seok Bae, Dong Ho Lee, Haeryoung Kim, Kyung-Suk Suh, Kwang-Woong Lee, Jae Young Lee, Byung Ihn Choi, Joon Koo Han, Kyung Bun Lee, Nam-Joon Yi, and Eun Sun Lee
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medicine.medical_specialty ,medicine.diagnostic_test ,business.industry ,medicine.medical_treatment ,Ultrasound ,Area under the curve ,Interventional radiology ,General Medicine ,Odds ratio ,Gastroenterology ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,030220 oncology & carcinogenesis ,Internal medicine ,medicine ,Radiology, Nuclear Medicine and imaging ,Radiology ,Hepatectomy ,Transient elastography ,Complication ,business ,Neuroradiology - Abstract
Both transient elastography (TE) and 2D shear wave elastography (SWE) are accurate methods to evaluate liver fibrosis. We aimed to evaluate the diagnostic performance of 2D-SWE in predicting post-hepatectomy complication and to compare it with TE. We prospectively enrolled 125 patients with liver tumors. Liver stiffness (LS) (kilopascal [kPa]) was measured using both TE and 2D-SWE before surgery. All post-operative complication was evaluated using the comprehensive complication index (CCI), and CCI ≥ 26.2 was defined as severe complication. Logistic regression analysis was performed to identify predictive factors for severe complication. Receiver operating characteristic analysis was used to evaluate the diagnostic performance of TE/2D-SWE in detecting liver fibrosis and severe complication. Severe complication developed in 18 patients. The median LS in patients with severe complication was significantly higher for both 2D-SWE (11.4 kPa vs. 7.0 kPa, p
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- 2021
19. Unpaired medical image colorization using generative adversarial network
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Byeong-Seok Shin, Dong-Ho Lee, Yan Li, and Yihuai Liang
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Computer Networks and Communications ,Computer science ,Structural similarity ,business.industry ,Color image ,media_common.quotation_subject ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,020207 software engineering ,Pattern recognition ,02 engineering and technology ,Function (mathematics) ,Grayscale ,Image (mathematics) ,Image colorization ,Hardware and Architecture ,0202 electrical engineering, electronic engineering, information engineering ,Media Technology ,Leverage (statistics) ,020201 artificial intelligence & image processing ,Quality (business) ,Artificial intelligence ,business ,Generative adversarial network ,Software ,media_common - Abstract
We consider medical image transformation problems where a grayscale image is transformed into a color image. The colorized medical image should have the same features as the input image because extra synthesized features can increase the possibility of diagnostic errors. In this paper, to secure colorized medical images and improve the quality of synthesized images, as well as to leverage unpaired training image data, a colorization network is proposed based on the cycle generative adversarial network (CycleGAN) model, combining a perceptual loss function and a total variation (TV) loss function. Visual comparisons and experimental indicators from the NRMSE, PSNR, and SSIM metrics are used to evaluate the performance of the proposed method. The experimental results show that GAN-based style conversion can be applied to colorization of medical images. As well, the introduction of perceptual loss and TV loss can improve the quality of images produced as a result of colorization better than the result generated by only using the CycleGAN model.
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- 2021
20. Reducing Pain by Artificial Ascites Infusion During Radiofrequency Ablation for Subcapsular Hepatocellular Carcinoma
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Joon Koo Han, Dong Ho Lee, and Sae Jin Park
- Subjects
medicine.medical_specialty ,business.industry ,Radiofrequency ablation ,Therapeutic effect ,Ultrasound ,Subgroup analysis ,medicine.disease ,Gastroenterology ,030218 nuclear medicine & medical imaging ,law.invention ,03 medical and health sciences ,0302 clinical medicine ,Opioid ,Tumor progression ,law ,Internal medicine ,Hepatocellular carcinoma ,medicine ,Mann–Whitney U test ,Radiology, Nuclear Medicine and imaging ,Cardiology and Cardiovascular Medicine ,business ,medicine.drug - Abstract
To evaluate therapeutic effects of artificial ascites (AA) infusion in patients with subcapsular hepatocellular carcinoma (HCC) treated with radiofrequency ablation (RFA) and to determine whether this infusion can reduce pain. From 2011 to 2016, 123 patients with treatment-naive single subcapsular HCC (≤ 2.5 cm) who underwent RFA were retrospectively included. Patients were divided into two groups according to AA infusion. After RFA, medical records were used to analyze pain scores during a 24-h period and to determine the opioid used that compared using Mann–Whitney U test. We also conducted subgroup analysis of the patients with HCCs located adjacent to parietal peritoneum. After follow-up period, we analyzed local tumor progression (LTP) and recurrence-free survival using Kaplan–Meier method. AA was infused in 76 patients (61.8%, 76/123). Pain score using numeric rating scale (NRS) was significantly lower in AA infusion group than in control group (2.54 ± 2.8 vs. 3.66 ± 3.2, p = 0.048). Dose of opioids used was not significantly different between two groups (1.62 ± 3.4 mg vs. 1.66 ± 3 mg, p = 0.698). However, in subgroup analysis (N = 45), NRS score and dose of opioids used were significantly lower in AA infusion group (p = 0.03, p = 0.032, respectively). LTP rate was not significantly different between two groups (p = 0.673). AA infusion was an effective and safe way to reduce pain when performing RFA for subcapsular HCC. In particular, in patients with subcapsular HCC adjacent to parietal peritoneum, dose of opioid to use pain control was significantly lower with AA infusion.
- Published
- 2021
21. Hepatobiliary phase of gadoxetic acid–enhanced MRI in patients with HCC: prognostic features before resection, ablation, or TACE
- Author
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Dong Ho Lee, Joon Koo Han, Jae Seok Bae, Jung Hoon Kim, and Jae Hyun Kim
- Subjects
medicine.medical_specialty ,Gadoxetic acid ,Radiofrequency ablation ,Gastroenterology ,030218 nuclear medicine & medical imaging ,law.invention ,03 medical and health sciences ,0302 clinical medicine ,law ,Internal medicine ,medicine ,Radiology, Nuclear Medicine and imaging ,Stage (cooking) ,medicine.diagnostic_test ,business.industry ,Proportional hazards model ,Hazard ratio ,Magnetic resonance imaging ,General Medicine ,medicine.disease ,030220 oncology & carcinogenesis ,Hepatocellular carcinoma ,Radiology ,Liver cancer ,business ,medicine.drug - Abstract
Patients with hepatocellular carcinoma (HCC) receiving different treatments might have specific prognostic factors that can be captured in the hepatobiliary phase (HBP) of gadoxetic acid–enhanced magnetic resonance imaging (GA-MRI). We aimed to identify the clinical findings and HBP features with prognostic value in patients with HCC. In this retrospective, single-institution study, we included patients with Barcelona Clinic Liver Cancer very early/early stage HCC who underwent GA-MRI before treatment. After performing propensity score matching, 183 patients received the following treatments: resection, radiofrequency ablation (RFA), and transarterial chemoembolization (TACE) (n = 61 for each). Cox regression models were used to identify clinical factors and HBP features associated with disease-free survival (DFS) and overall survival (OS). In the resection group, large tumor size was associated with poor DFS (hazard ratio [HR] 4.159 per centimeter; 95% confidence interval [CI], 1.669–10.365) and poor OS (HR 8.498 per centimeter; 95% CI, 1.072–67.338). In the RFA group, satellite nodules on HBP images were associated with poor DFS (HR 5.037; 95% CI, 1.061–23.903) and poor OS (HR 9.398; 95% CI, 1.480–59.668). Peritumoral hypointensity on HBP images was also associated with poor OS (HR 13.062; 95% CI, 1.627–104.840). In addition, serum albumin levels and the prothrombin time-international normalized ratio were associated with DFS and/or OS. Finally, in the TACE group, no variables were associated with DFS/OS. Different HBP features and clinical factors were associated with DFS/OS among patients with HCC receiving different treatments. • In patients who underwent resection for HCC, a large tumor size on HBP images was associated with poor disease-free survival and overall survival. • In the RFA group, satellite nodules and peritumoral hypointensity on HBP images, along with decreased serum albumin levels and PT-INR, were associated with poor disease-free survival and/or overall survival. • In the TACE group, no clinical or HBP imaging features were associated with disease-free survival or overall survival.
- Published
- 2020
22. Association between spleen volume and the post-hepatectomy liver failure and overall survival of patients with hepatocellular carcinoma after resection
- Author
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Jeongin Yoo, Haeryoung Kim, Kyung Bun Lee, Kyung-Suk Suh, Kwang-Woong Lee, Jae Seok Bae, Dong Ho Lee, and Nam-Joon Yi
- Subjects
medicine.medical_specialty ,Carcinoma, Hepatocellular ,medicine.medical_treatment ,Gastroenterology ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,Internal medicine ,medicine ,Hepatectomy ,Humans ,Radiology, Nuclear Medicine and imaging ,Stage (cooking) ,Retrospective Studies ,Body surface area ,Receiver operating characteristic ,Proportional hazards model ,business.industry ,Liver Neoplasms ,Hazard ratio ,General Medicine ,Odds ratio ,medicine.disease ,030220 oncology & carcinogenesis ,Hepatocellular carcinoma ,Radiology ,business ,Liver Failure ,Spleen - Abstract
Post-hepatectomy liver failure (PHLF) can occur as a major complication after hepatic resection (HR) in patients with hepatocellular carcinoma (HCC) and negatively affects the prognosis. We aimed to retrospectively assess whether the spleen volume (SV) measured from preoperative CT images would be associated with the development of PHLF and overall survival (OS) after HR in patients with HCC. We enrolled 317 consecutive patients with very early/early stage HCC who underwent a preoperative CT and HR between January 2010 and December 2016. The SV was obtained from preoperative CT images using semi-automated volumetric software and was divided by body surface area to yield SVBSA. Receiver operating characteristic (ROC) curves and logistic regression analyses were performed to identify factors affecting the development of PHLF. The Cox proportional hazard model was used to identify prognostic factors for OS. PHLF was observed in 72 patients (22.7% [72/317]). SVBSA was associated with the development of PHLF (odds ratio, 2.321; 95% CI, 1.347–4.001; p = 0.002) with the area under the ROC curve of 0.663 using the cutoff value of 107.5 cm3 (p 146 cm3 (95.0% vs. 78.7%, p < 0.001). In patients with HCC, a larger SVBSA was associated with a higher rate of PHLF and worse OS after HR. The SVBSA may be useful in selecting good surgical candidates. • A significantly higher spleen volume divided by body surface area was observed in patients who experienced post-hepatectomy liver failure than in patients who did not (148 cm 3 vs. 112 cm 3 , p < 0.001). • The area under the receiver operating characteristic curve of spleen volume divided by body surface area to predict the development of post-hepatectomy liver failure was 0.663 (p < 0.001). • Spleen volume divided by body surface area was a significant influencing factor for overall survival (hazard ratio, 3.935; 95% CI, 1.520–10.184; p < 0.001), with the optimal cutoff of 146 cm 3 .
- Published
- 2020
23. Prognostic role of spleen volume measurement using computed tomography in patients with compensated chronic liver disease from hepatitis B viral infection
- Author
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Eun Ju Cho, Dong Ho Lee, Jeongin Yoo, Jae Seok Bae, and S.-W. Kim
- Subjects
medicine.medical_specialty ,medicine.diagnostic_test ,business.industry ,Spleen ,Interventional radiology ,General Medicine ,Chronic liver disease ,medicine.disease ,Gastroenterology ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,medicine.anatomical_structure ,030220 oncology & carcinogenesis ,Internal medicine ,Hepatocellular carcinoma ,medicine ,Radiology, Nuclear Medicine and imaging ,Decompensation ,In patient ,Cumulative incidence ,Radiology ,business ,Neuroradiology - Abstract
To determine the prognostic value of CT-based splenic volume measurement in patients with compensated chronic liver disease (cCLD) from chronic hepatitis B (CHB). A total of 584 patients having multiphasic liver CT scans between January and December 2011 were retrospectively reviewed. Spleen volume was measured using a semi-automated three-dimensional volumetric software program. Electronic medical records and national registry data were reviewed to determine the diagnosis of hepatocellular carcinoma (HCC), hepatic decompensation, or death. The cumulative incidence (CI) of the development of decompensation, HCC occurrence, and overall survival (OS) were estimated by the Kaplan-Meier method. The Cox proportional hazard regression model was used to evaluate prognostic factors. The optimal cutoff spleen volume to predict each outcome was obtained using a minimal p value approach method. After a median follow-up of 92 months, 114 patients developed HCC with a 7-year CI of 17.2%. A larger spleen volume was a significant predictor of HCC occurrence (HR = 2.13, p = 0.009). Decompensation occurred in 30 patients with a 7-year CI of 5.0%, and a larger spleen volume was also significantly associated with the development of decompensation (HR = 4.66, p = 0.005). Twenty-three patients died, and their estimated 7-year OS was 96.4%. A larger spleen volume also significantly affected OS (HR = 6.15, p = 0.007). The optimal cutoff spleen volume was set at 532 mL for HCC occurrence, 656.9 mL for the development of decompensation, and 741.1 mL for OS. A larger spleen volume was significantly associated with HCC occurrence, development of decompensation, and poor OS in patients with cCLD from CHB. • Spleen volume could be easily acquired from routine multiphasic liver CT scan using a semi-automated 3D volumetric software program with excellent inter-observer agreement. • A larger spleen volume was significantly associated with a higher rate of hepatocellular carcinoma occurrence, the development of decompensation, and poor overall survival in patients with compensated chronic liver disease from chronic hepatitis B.
- Published
- 2020
24. Clinical outcomes of patients with a high alpha-fetoprotein level but without evident recurrence on CT or MRI in surveillance after curative-intent treatment for hepatocellular carcinoma
- Author
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Jeong Min Lee, Ijin Joo, Dong Ho Lee, Jihyuk Lee, and Sun Kyung Jeon
- Subjects
medicine.medical_specialty ,Radiofrequency ablation ,Urology ,030218 nuclear medicine & medical imaging ,law.invention ,03 medical and health sciences ,0302 clinical medicine ,law ,Internal medicine ,Carcinoma ,Medicine ,Radiology, Nuclear Medicine and imaging ,Curative intent ,Radiological and Ultrasound Technology ,business.industry ,Proportional hazards model ,Gastroenterology ,Hepatology ,medicine.disease ,digestive system diseases ,030220 oncology & carcinogenesis ,Hepatocellular carcinoma ,Radiology ,business ,Alpha-fetoprotein ,After treatment - Abstract
Multiphasic CT or MRI and serum alpha-fetoprotein (AFP) are widely used for posttreatment surveillance of hepatocellular carcinoma (HCC). This study aimed to investigate the clinical outcomes of patients with high posttreatment AFP but without evident recurrence on CT or MRI after curative-intent treatment of HCC. We retrospectively analyzed 121 patients presenting with high posttreatment AFP (> 20 ng/mL) without evident recurrence on multiphasic CT or MRI during surveillance after curative-intent surgical resection or radiofrequency ablation (RFA) for HCC. The time interval from the first event of high posttreatment AFP to imaging-evident recurrence (TimeAFP-Imaging recurrence) was estimated using the Kaplan–Meier method. Cox regression analyses were performed to assess the associated factors with TimeAFP-Imaging recurrence. The median TimeAFP-Imaging recurrence was 20.0 months (95% CI 13.0–28.0 months), and the estimated 6-month and 1-year cumulative incidences of imaging-evident recurrence were 24.4% and 40.1%, respectively. In multivariate Cox analyses, late onset of AFP elevation (> 3 months after treatment) was an independent predictor of shorter TimeAFP-Imaging recurrence (HR 2.11, P = 0.015) if using variables available at the first event of AFP elevation, while non-normalization of AFP at the next follow-up was an independent predictor of shorter TimeAFP-Imaging recurrence (HR 3.65, P
- Published
- 2020
25. Abdominal obesity increases risk for esophageal cancer: a nationwide population-based cohort study of South Korea
- Author
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Kyungdo Han, Young Soo Park, Nayoung Kim, Hyuk Yoon, Cheol Min Shin, Jae Ho Cho, and Dong Ho Lee
- Subjects
Adult ,Male ,medicine.medical_specialty ,Esophageal Neoplasms ,Overweight ,Body Mass Index ,Cohort Studies ,03 medical and health sciences ,0302 clinical medicine ,Risk Factors ,Internal medicine ,Republic of Korea ,medicine ,Humans ,Risk factor ,Abdominal obesity ,Aged ,Retrospective Studies ,business.industry ,Gastroenterology ,Retrospective cohort study ,Middle Aged ,Esophageal cancer ,medicine.disease ,Obesity, Abdominal ,030220 oncology & carcinogenesis ,Cohort ,Female ,030211 gastroenterology & hepatology ,Esophageal Squamous Cell Carcinoma ,Waist Circumference ,medicine.symptom ,business ,Body mass index ,Follow-Up Studies ,Abdominal surgery - Abstract
The relationship between overall obesity, as measured by body mass index (BMI) and risk of esophageal squamous cell carcinoma (ESCC) has been reported to show a negative correlation. However, the relationship of ESCC, which accounts for around 90% of esophageal cancers in South Korea, with abdominal obesity, as measured by waist circumference (WC), may be different. Thus, we investigated the association between abdominal obesity and esophageal cancer in a nationwide population-based cohort. A retrospective cohort study of 22,809,722 individuals who had undergone regular health check-ups provided by the National Health Insurance Corporation between 2009 and 2012 (median follow-up period, 6.4 years) in South Korea was conducted. Abdominal obesity was defined as a WC > 90 cm for men and > 85 cm for women. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) using χ2 test and Cox proportional hazards model adjusted for confounding factors. The primary outcome was newly developed esophageal cancer. After adjusting for BMI, abdominal obesity increased the risk of esophageal cancer (HR 1.29, 95% CI 1.23–1.36). WC increased the risk for esophageal cancer in a dose-dependent manner (p values for trend
- Published
- 2019
26. Risk of Dementia in Gastric Cancer Survivors Who Underwent Gastrectomy: A Nationwide Study in Korea
- Author
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Dong Wook Shin, Dong Ho Lee, Yong Gyu Park, Sang Hyun Park, Su-Min Jeong, Yoon Jin Choi, Wooyoung Jang, and Kyungdo Han
- Subjects
Male ,medicine.medical_specialty ,medicine.medical_treatment ,Population ,Gastroenterology ,03 medical and health sciences ,0302 clinical medicine ,Gastrectomy ,Risk Factors ,Stomach Neoplasms ,Internal medicine ,Republic of Korea ,medicine ,Humans ,Dementia ,Survivors ,education ,Vascular dementia ,Survival rate ,Retrospective Studies ,education.field_of_study ,business.industry ,Incidence ,Hazard ratio ,Case-control study ,Cancer ,Middle Aged ,Prognosis ,medicine.disease ,Survival Rate ,Oncology ,Case-Control Studies ,030220 oncology & carcinogenesis ,Female ,030211 gastroenterology & hepatology ,Surgery ,business ,Follow-Up Studies - Abstract
This study was designed to compare the risk of dementia, including Alzheimer’s disease (AD) and vascular dementia (VaD), between gastric cancer patients who underwent gastrectomy and the general population. All patients (n = 63,998) aged ≥ 50 years who received a diagnosis of gastric cancer and underwent curative gastrectomy between 2007 and 2012 and a noncancer control population (n = 203,276), matched by age and sex, were identified from the Korean National Health Insurance Services and traced until 2017. Hazard ratios and 95% confidence intervals for dementia were calculated with a Cox regression analysis. Gastric cancer patients who received a gastrectomy showed an increased risk of AD [adjusted hazard ration (aHR) 1.08, 95% confidence interval (CI) 1.03–1.14], and the risk was especially marked for those who received a total gastrectomy (aHR 1.39, 95% CI 1.25–1.54). Gastric cancer survivors showed a decreased risk for VaD (aHR 0.85; 95% CI 0.73–0.98) regardless of operation type. Those who received continual vitamin B12 supplementation after a total gastrectomy were less likely than controls to develop AD (aHR 0.71; 95% CI 0.54–0.92). Compared with controls, gastric cancer patients who received a total gastrectomy had an increased incidence of AD and a decreased risk of VaD. Our results suggest that vitamin B12 deficiency might play a role in the development of AD and highlight the need for vitamin B12 supplementation after total gastrectomy.
- Published
- 2019
27. Assessment of hepatic steatosis by using attenuation imaging: a quantitative, easy-to-perform ultrasound technique
- Author
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Haeryoung Kim, Jeong Hoon Lee, Dong Ho Lee, Joon Koo Han, Jae Young Lee, Yun Bin Lee, Su Jong Yu, Byung Ihn Choi, Eun Ju Cho, and Jae Seok Bae
- Subjects
Adult ,Male ,medicine.medical_specialty ,Biopsy ,Sensitivity and Specificity ,Severity of Illness Index ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,Liver disease ,0302 clinical medicine ,Image Interpretation, Computer-Assisted ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,Prospective Studies ,Stage (cooking) ,Ultrasonography ,medicine.diagnostic_test ,Receiver operating characteristic ,business.industry ,Biopsy, Needle ,Ultrasound ,Reproducibility of Results ,General Medicine ,Gold standard (test) ,Middle Aged ,medicine.disease ,Fatty Liver ,Liver ,ROC Curve ,Evaluation Studies as Topic ,030220 oncology & carcinogenesis ,Female ,Histopathology ,Radiology ,Steatosis ,business - Abstract
To evaluate the diagnostic performance of attenuation imaging (ATI) in the detection of hepatic steatosis compared with a histopathology gold standard. We prospectively enrolled 108 consecutive patients (35 males; median age, 54.0 years) who underwent percutaneous liver biopsy for evaluation of diffuse liver disease between January 2018 and November 2018 in a tertiary academic center. Grayscale ultrasound examination with ATI was performed just before biopsy, and an attenuation coefficient (AC) was obtained from each patient. The degree of hepatic steatosis, fibrosis stage, and necroinflammatory activity were assessed on histopathologic examination. The significant factor associated with the AC was found by a linear regression analysis, and the diagnostic performance of the AC for the classification into each hepatic steatosis stage was evaluated by receiver operating characteristic (ROC) analysis. The distribution of hepatic steatosis grade on histopathology was 53/11/22/16/6 for none/mild (
- Published
- 2019
28. Highly Efficient and Highly Conductive Phosphor-in-Glass Materials for Use in LD-Driven White-Light Lamp
- Author
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Sunil Kim, Dong-Ho Lee, Hyungsun Kim, and Sun-Kyu Lee
- Subjects
0209 industrial biotechnology ,Materials science ,Renewable Energy, Sustainability and the Environment ,business.industry ,Mechanical Engineering ,Extraction (chemistry) ,Thermal effect ,Phosphor ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Industrial and Manufacturing Engineering ,Glass material ,020901 industrial engineering & automation ,Management of Technology and Innovation ,White light ,Sapphire ,Degradation (geology) ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business ,Electrical conductor - Abstract
This paper presents a highly efficient and highly conductive phosphor-in-glass (PIG) material with additives for use as a white conversion component in laser-diode-driven white-light systems. Conductive additive materials such as sapphire powder were used to lessen the thermally induced degradation of the phosphor. First, the light extraction efficiency was investigated by modulating the ratio of the additive in a simulation using a light extraction model. On the basis of simulation results for the proposed PIG, both transmission-type and reflection-type sapphire phosphor-in-glass samples were fabricated and evaluated. We performed comparisons between the fabricated sapphire and glass-grit phosphors at different phosphor weight percentages. We confirmed that the sapphire powder significantly enhanced the light extraction efficiency and heat dissipation of the system. The measured light extraction efficiency coupled with the thermal effect for the reflection-type samples agreed with the simulation results.
- Published
- 2019
29. Subclinical gait disturbance and postoperative gait improvement in patients with degenerative cervical myelopathy
- Author
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Kun-Bo Park, Chung Hwan Kim, Jung-Ki Ha, Choon Sung Lee, Jae Hwan Cho, Jong Yoon Yoo, Chang Ju Hwang, and Dong Ho Lee
- Subjects
Adult ,Male ,medicine.medical_specialty ,Science ,Diseases ,Asymptomatic ,Article ,Spinal Cord Diseases ,03 medical and health sciences ,Myelopathy ,0302 clinical medicine ,Gait (human) ,Physical medicine and rehabilitation ,Humans ,Medicine ,In patient ,Postoperative Period ,Signs and symptoms ,Aged ,Retrospective Studies ,Subclinical infection ,030222 orthopedics ,Multidisciplinary ,business.industry ,Gait Disturbance ,Health care ,Middle Aged ,medicine.disease ,medicine.anatomical_structure ,Gait analysis ,Cervical Vertebrae ,Female ,Ankle ,medicine.symptom ,Gait Analysis ,business ,human activities ,030217 neurology & neurosurgery - Abstract
This study aimed to evaluate the subclinical gait abnormalities and the postoperative gait improvements in patients with degenerative cervical myelopathy using three-dimensional gait analysis. We reviewed the gait analysis of 62 patients who underwent surgical treatment for degenerative cervical myelopathy. The asymptomatic gait group included 30 patients and the gait disturbance group included 32 patients who can walk on their own slowly or need assistive device on stairs. The step width (17.2 cm vs. 15.9 cm, P = 0.003), stride length (105.2 cm vs. 109.1 cm, P = 0.015), and double-limb support duration (13.4% vs. 11.7%, P = 0.027) improved only in the asymptomatic gait group. Preoperatively, the asymptomatic gait group exhibited better maximum knee flexion angle (60.5° vs. 54.8°, P = 0.001) and ankle plantarflexion angle at push-off (− 12.2° vs. − 6.5°, P = 0.001) compared to the gait disturbance group. Postoperatively, maximum knee flexion angle (62.3° vs. 58.2°, P = 0.004) and ankle plantarflexion angle at push-off (− 12.8° vs. − 8.3°, P = 0.002) were still better in the asymptomatic gait group, although both parameters improved in the gait disturbance group (P = 0.005, 0.039, respectively). Kinematic parameters could improve in patients with gait disturbance. However, temporospatial parameters improvement may be expected when the operative treatment is performed before apparent gait disturbance.
- Published
- 2021
30. Retrospective validation of a new diagnostic criterion for hepatocellular carcinoma on gadoxetic acid-enhanced MRI: can hypointensity on the hepatobiliary phase be used as an alternative to washout with the aid of ancillary features?
- Author
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Ijin Joo, Joon Koo Han, Jeong Min Lee, Dong Ho Lee, and Ju Hyeon Jeon
- Subjects
Gadolinium DTPA ,Male ,medicine.medical_specialty ,Gadoxetic acid ,Carcinoma, Hepatocellular ,Contrast Media ,Sensitivity and Specificity ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,McNemar's test ,Image Interpretation, Computer-Assisted ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,Aged ,Retrospective Studies ,Neuroradiology ,medicine.diagnostic_test ,Portal Vein ,business.industry ,Liver Neoplasms ,Ultrasound ,Washout ,Magnetic resonance imaging ,General Medicine ,Middle Aged ,HCCS ,medicine.disease ,Magnetic Resonance Imaging ,digestive system diseases ,030220 oncology & carcinogenesis ,Hepatocellular carcinoma ,Female ,Radiology ,business ,medicine.drug - Abstract
To validate new diagnostic criteria for hepatocellular carcinoma (HCC) on gadoxetic acid-enhanced MR imaging (Gd-EOB-MRI) using hypointensity on the hepatobiliary phase (HBP) as an alternative to washout in combination with ancillary features.This retrospective study included 288 patients at high risk for HCC with 387 nodules (HCCs, n=292; non-HCCs, n=95) showing arterial phase hyper-enhancement (APHE) ≥1 cm on Gd-EOB-MRI. Imaging diagnoses of HCCs were made using different criteria: APHE plus hypointensity on the portal venous phase (PVP) (criterion 1), APHE plus hypointensity on the PVP and/or transitional phase (TP) (criterion 2), APHE plus hypointensity on the PVP and/or TP and/or HBP (criterion 3), and criterion 3 plus non-LR-1/2/M according to the Liver Imaging Reporting and Data System (LI-RADS) v2017 considering ancillary features (criterion 4). Sensitivities and specificities of those criteria were compared using McNemar's test.Among diagnostic criteria for HCCs, criteria 3 and 4 showed significantly higher sensitivities (93.8% and 92.5%, respectively) than criteria 1 and 2 (70.9% and 86.6%, respectively) (p values0.001). The specificity of criterion 4 (87.4%) was shown to be significantly higher than that of criterion 3 (48.4%, p0.001), albeit comparable to criterion 2 (86.3%, p0.999) and significantly lower than criterion 1 (97.9%, p=0.002).In the non-invasive diagnosis of HCCs on Gd-EOB-MRI, HBP hypointensity may be used as an alternative to washout enabling a highly sensitive diagnosis with little loss in specificity if it is used after excluding nodules considered to be benignities or non-HCC malignancies based on characteristic imaging features.• Gd-EOB-MRI enhancement and ancillary features can be used to diagnose HCC. • Exclusion of LR-1/2/M improves specificity when HBP hypointensity is used.
- Published
- 2018
31. Abdominal obesity, glucose intolerance and decreased high-density lipoprotein cholesterol as components of the metabolic syndrome are associated with the development of colorectal cancer
- Author
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Cheol Min Shin, Yoon Jin Choi, Kyungdo Han, Dong Ho Lee, and Nayoung Kim
- Subjects
Adenoma ,Male ,medicine.medical_specialty ,Epidemiology ,Colorectal cancer ,Blood Pressure ,Gastroenterology ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,High-density lipoprotein ,Internal medicine ,Glucose Intolerance ,Republic of Korea ,Humans ,Medicine ,030212 general & internal medicine ,Abdominal obesity ,Metabolic Syndrome ,business.industry ,Cholesterol ,Cholesterol, HDL ,Hazard ratio ,medicine.disease ,chemistry ,Obesity, Abdominal ,030220 oncology & carcinogenesis ,Cohort ,Female ,Metabolic syndrome ,medicine.symptom ,Colorectal Neoplasms ,business - Abstract
Metabolic syndrome (MetS) and its components has been thought to be involved in the development of colorectal cancer (CRC). However, the results is often inconsistent according to gender or anatomical location of tumor. This study aimed to investigate the association between MetS and its components and CRC development by gender and tumor location. We evaluated the data of 22,809,722 Korean individuals of the National semi-compulsive cohort who underwent regular health check-ups between 2009 and 2012. Compared to subjects without MetS components, the hazard ratio for CRC development in patients with MetS was 1.22 (95% Confidence Interval [CI] 1.20–1.24) and this association was more prominent in men than in women (HR 1.41 95% CI 1.37–1.44 vs. HR 1.23 95% CI 1.20–1.27, P for interaction
- Published
- 2018
32. Effects of Start and Finish Cooling Temperatures on the Yield Strength and Uniform Elongation of Strain-Based API X100 Pipeline Steels
- Author
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Hyejin Song, Dong Ho Lee, Yunjo Ro, Seok Su Sohn, Byoungchul Hwang, Sunghak Lee, and Chang Sun Lee
- Subjects
010302 applied physics ,Austenite ,Materials science ,Bainite ,Metallurgy ,Metals and Alloys ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,01 natural sciences ,Acicular ferrite ,Mechanics of Materials ,Ferrite (iron) ,0103 physical sciences ,Elongation ,0210 nano-technology ,Supercooling ,Dynamic strain aging - Abstract
Three types of strain-based API X100 pipeline steels composed of polygonal ferrite (PF), acicular ferrite (AF), granular bainite (GB), bainitic ferrite (BF), and martensite–austenite (MA) were fabricated by varying the start cooling temperature (SCT) and finish cooling temperature (FCT). The effect of the microstructure on the yield strength and uniform elongation before and after strain aging was investigated. In the H-H steel fabricated at a high SCT and low FCT, the reduction in uniform elongation after prestraining was small, but the uniform elongation after heat treatment increased because of the presence of many mobile dislocations around AF and GB, which are present in a relatively high fraction. Because the H-L steel fabricated at high SCT and low FCT has a considerable amount of BF as a result of the significant degree of supercooling, carbon atoms were readily trapped at dislocations inside the BF during heat treatment, which reduced the resistance to strain aging. On the other hand, the L-L steel had a large amount of soft PF transformed in the two-phase (austenite + ferrite) region and high fractions of AF and MA because it was fabricated at low SCT and low FCT. As a result, the uniform elongation of the L-L steel was slightly increased after heat treatment because mobile dislocations were readily generated around the PF and MA boundaries under deformation.
- Published
- 2018
33. An exploratory study on the effect of daily fruits and vegetable juice on human gut microbiota
- Author
-
Yoon Keun Kim, Hyun Soo Kim, Dong Ho Lee, and Yoon Jin Choi
- Subjects
0301 basic medicine ,Human feces ,Abdominal pain ,Constipation ,biology ,business.industry ,Physiology ,Extracellular vesicle ,Gut flora ,Body weight ,biology.organism_classification ,Applied Microbiology and Biotechnology ,Article ,03 medical and health sciences ,Diarrhea ,030104 developmental biology ,0302 clinical medicine ,Human gut ,medicine ,030211 gastroenterology & hepatology ,medicine.symptom ,business ,Food Science ,Biotechnology - Abstract
In order to evaluate the effect of daily consumption of fruit and vegetable juice on the human intestinal microbial community, we compared changes in the gut microbiota and extracellular vesicles in human feces and bowel, and skin symptoms at the baseline and 3 weeks post juice consumption of 22 participants. After 3 weeks of juice consumption, a significant increase in the richness of microbiota (α-diversity, P
- Published
- 2018
34. A sample average approximation algorithm for selective disassembly sequencing with abnormal disassembly operations and random operation times
- Author
-
Hyung-Won Kim and Dong-Ho Lee
- Subjects
Quantitative Biology::Biomolecules ,0209 industrial biotechnology ,Sequence ,021103 operations research ,Stochastic integer programming ,Branch and bound ,Computer science ,Mechanical Engineering ,0211 other engineering and technologies ,02 engineering and technology ,Industrial and Manufacturing Engineering ,Computer Science Applications ,Process graph ,Quantitative Biology::Subcellular Processes ,020901 industrial engineering & automation ,Control and Systems Engineering ,Sample average approximation ,Product (mathematics) ,Physics::Atomic and Molecular Clusters ,Hardware_REGISTER-TRANSFER-LEVELIMPLEMENTATION ,Algorithm ,Software - Abstract
Selective disassembly sequencing is the problem of determining the sequence of disassembly operations to extract one or more target components of a product. This study addresses a stochastic version of the problem in which abnormal disassembly operations and random operation times are considered under the parallel disassembly environment, i.e., one or more components that can be disassembled further remain after a disassembly operation is done. Abnormal disassembly operations are defined as those in which fasteners can be removed by additional random destructive operations without damaging to target components. After representing all possible sequences using the extended process graph, a stochastic integer programming model is developed that minimizes the sum of disassembly and penalty costs, where the disassembly cost consists of sequence-dependent setup and operation costs, and the penalty cost is the expectation of the costs incurred when the total disassembly time exceeds a given threshold value. A sample average approximation algorithm is proposed that incorporates a branch and bound algorithm to solve the deterministic problem under a scenario for abnormal operations and operation times optimally. Finally, the algorithm is illustrated with a hand-light example and a larger instance.
- Published
- 2018
35. Magnetic resonance with diffusion-weighted imaging improves assessment of focal liver lesions in patients with potentially resectable pancreatic cancer on CT
- Author
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Hyunsik Woo, Ijin Joo, Su Joa Ahn, Jeong Min Lee, Joon Koo Han, Dong Ho Lee, Jin-Young Jang, Sun Kyung Jeon, and Myoung Seok Lee
- Subjects
Adult ,Male ,medicine.medical_specialty ,Sensitivity and Specificity ,030218 nuclear medicine & medical imaging ,Metastasis ,03 medical and health sciences ,0302 clinical medicine ,Pancreatic cancer ,Multidetector Computed Tomography ,Preoperative Care ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries) ,Aged ,Neoplasm Staging ,Retrospective Studies ,Neuroradiology ,Aged, 80 and over ,medicine.diagnostic_test ,business.industry ,Liver Neoplasms ,Ultrasound ,Interventional radiology ,Magnetic resonance imaging ,General Medicine ,Middle Aged ,medicine.disease ,Pancreatic Neoplasms ,Diffusion Magnetic Resonance Imaging ,medicine.anatomical_structure ,Liver ,030220 oncology & carcinogenesis ,Female ,Radiology ,Pancreas ,business ,Carcinoma, Pancreatic Ductal ,Diffusion MRI - Abstract
To investigate added value of MRI to preoperative staging MDCT for evaluation of focal liver lesions (FLLs) in potentially resectable pancreatic ductal adenocarcinomas (PDACs).In patients with potentially resectable PDACs after staging MDCT (n=167), characteristics of FLLs were scored as benign, indeterminate or metastases on an MDCT set and combined MDCT and MRI set by two readers, independently. Size of hepatic lesions was measured and detection rate of hepatic metastasis unsuspected by MDCT and diagnostic yield of MRI for FLLs were assessed.Reader-averaged figure-of-merit (FOM) of the combined set was significantly higher than that of MDCT alone (0.94 vs. 0.86, p=.028). In the negative-on-CT group, the diagnostic yield of MRI was 1.5-2.3% (2/133 and 3/133 for readers 1 and 2, respectively). In the indeterminate-on-CT group, MRI yield was 10.5-13.6% (2/19 and 3/22) and in patients with suspicious-metastasis-on-CT, 8.3-26.7% (1/12 and 4/15). All lesions with false-positive and false-negative CT findings were ≤1 cm.In potentially resectable PDACs, addition of MRI with DWI can provide significantly better diagnostic performance in characterization of focal liver lesions, especially for small-sized (≤ 1 cm) MDCT-indeterminate or suspicious metastasis lesions, aiding in determination of appropriate operation candidates.• Addition of MRI provides better diagnostic performance in characterization of liver lesions. • Combined interpretation of MRI and MDCT provided less frequent indeterminate liver lesions. • Diagnostic yield of MRI was high in CT-indeterminate or suspicious metastatic lesions. • Operation candidates can be determined with greater confidence in potentially resectable PDACs.
- Published
- 2018
36. Portal hypertension is associated with poor outcome of transarterial chemoembolization in patients with hepatocellular carcinoma
- Author
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Jin Wook Chung, Saebeom Hur, Hwan Jun Jae, Hyo Cheol Kim, Myungsu Lee, Jin Woo Choi, and Dong Ho Lee
- Subjects
Male ,medicine.medical_specialty ,Carcinoma, Hepatocellular ,Hypertension, Pulmonary ,Antineoplastic Agents ,Early death ,Iliac Artery ,Gastroenterology ,03 medical and health sciences ,0302 clinical medicine ,Internal medicine ,Catheterization, Peripheral ,Hypertension, Portal ,medicine ,Humans ,Infusions, Intra-Arterial ,Radiology, Nuclear Medicine and imaging ,In patient ,Pulmonary Wedge Pressure ,Chemoembolization, Therapeutic ,Grading (tumors) ,Retrospective Studies ,Neuroradiology ,medicine.diagnostic_test ,business.industry ,Liver Neoplasms ,Hazard ratio ,Interventional radiology ,General Medicine ,Middle Aged ,medicine.disease ,Treatment Outcome ,030220 oncology & carcinogenesis ,Hepatocellular carcinoma ,Portal hypertension ,Female ,030211 gastroenterology & hepatology ,Radiology ,business - Abstract
To determine whether clinically relevant portal hypertension (CRPH) influences outcome and whether it may serve as a prognostic marker in patients treated with transarterial chemoembolization (TACE) for hepatocellular carcinoma (HCC). One hundred and forty-seven patients underwent conventional TACE as a first-line treatment for a single HCC. CRPH was graded as 0, 1, or 2. The influence of CRPH, together with other factors, on local tumour progression (LTP) and overall survival (OS) were analysed using Cox proportional hazards regression. A higher CRPH grade (grade 1, p = 0.005, hazard ratio [HR] = 3.282; grade 2, p
- Published
- 2017
37. CT Perfusion evaluation of gastric cancer: correlation with histologic type
- Author
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Ijin Joo, Joon Koo Han, Se Hyung Kim, and Dong Ho Lee
- Subjects
Male ,medicine.medical_specialty ,Intraclass correlation ,Perfusion scanning ,030218 nuclear medicine & medical imaging ,Diagnosis, Differential ,03 medical and health sciences ,0302 clinical medicine ,Stomach Neoplasms ,Humans ,Medicine ,Radiology, Nuclear Medicine and imaging ,Aged ,Neoplasm Staging ,Neuroradiology ,business.industry ,Ultrasound ,Area under the curve ,Cancer ,General Medicine ,Middle Aged ,medicine.disease ,ROC Curve ,030220 oncology & carcinogenesis ,Mann–Whitney U test ,bacteria ,Female ,Radiology ,Tomography, X-Ray Computed ,business ,Perfusion - Abstract
To prospectively evaluate if the perfusion parameters of gastric cancer can provide information on histologic subtypes of gastric cancer. We performed preoperative perfusion CT (PCT) and curative gastrectomy in 46 patients. PCT data were analysed using a dedicated software program. Perfusion parameters were obtained by two independent radiologists and were compared according to histologic type using Kruskal–Wallis, Mann–Whitney U test and receiver operating characteristic analysis. To assess inter-reader agreement, we used intraclass correlation coefficient (ICC). Inter-reader agreement for perfusion parameters was moderate to substantial (ICC = 0.585–0.678). Permeability surface value of poorly cohesive carcinoma (PCC) was significantly higher than other histologic types (47.3 ml/100 g/min in PCC vs 26.5 ml/100 g/min in non-PCC, P
- Published
- 2017
38. Tensile property improvement in Ti/Al clad sheets fabricated by twin-roll casting and annealing
- Author
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Sunghak Lee, Hyejin Song, Jung-Su Kim, and Dong Ho Lee
- Subjects
010302 applied physics ,Fabrication ,Materials science ,Annealing (metallurgy) ,Metallurgy ,Alloy ,Metals and Alloys ,Intermetallic ,02 engineering and technology ,engineering.material ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,01 natural sciences ,Brittleness ,Mechanics of Materials ,0103 physical sciences ,Ultimate tensile strength ,Materials Chemistry ,engineering ,Composite material ,0210 nano-technology ,Rule of mixtures - Abstract
A new fabrication method of Ti/Al clad sheet by bonding a thin Ti sheet on to Al alloy melt during twin-roll casting was presented to broaden industrial applications of Ti alloys. In the twin-roll-cast Ti/Al clad sheet, a homogeneously solidified microstructure existed in the cast Al side, while a Ti/Al interface did not contain pores, cracks, or lateral delamination, which indicated a successful fabrication. When this cast sheet was annealed at 400 °C, metallurgical bonding was expanded by interfacial diffusion, thereby leading to improvement in tensile properties. After the 600 °C-annealing, a TiAl3 intermetallic compound was formed at the Ti/Al interface, which deteriorated tensile properties because of its brittle characteristics. The yield and tensile strengths of the 400 °C-30-min-annealed sheet (132 MPa and 218 MPa, respectively) were higher than those (103 MPa and 203 MPa, respectively) calculated by a rule of mixtures using tensile properties of a 5052-O Al alloy and a pure Ti. Its ductility was also higher than that of 5052-O Al alloy (25%) or pure Ti (25%) because the strain at the interfacial delamination point reached 41%. The 400 °C-30-min-annealed sheet showed the overall homogenous deformation behavior by complimenting drawbacks of mono-layer of Al or Ti.
- Published
- 2017
39. Effects of C and Si on strain aging of strain-based API X60 pipeline steels
- Author
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Byeong-Joo Lee, Hyokyung Sung, Young-Woon Kim, Sunghak Lee, Seung-Pyo Hong, Jang Yong Yoo, Sang Yong Shin, Byoungchul Hwang, and Dong Ho Lee
- Subjects
Austenite ,Materials science ,020502 materials ,Metallurgy ,technology, industry, and agriculture ,Metals and Alloys ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,C content ,Acicular ferrite ,0205 materials engineering ,Mechanics of Materials ,Ferrite (iron) ,Volume fraction ,Ultimate tensile strength ,Materials Chemistry ,Elongation ,0210 nano-technology ,Dynamic strain aging - Abstract
Four types of strain-based API X60 pipeline steels were fabricated by varying the C and Si contents, and the effects of C and Si on strain aging were investigated. The 0.05 wt% C steels consisted mainly of polygonal ferrite (PF), whereas the 0.08 wt% C steels consisted of acicular ferrite (AF). The volume fraction of AF increased with increasing C content because C is an austenite stabilizer element. The volume fractions of bainitic ferrite (BF) of the 0.15 wt% Si steels were higher than those of the 0.25 wt% Si steels, whereas the volume fractions of the secondary phases were lower. From the tensile properties before and after the aging process of the strainbased API X60 pipeline steels, the yield strength increased and the uniform and total elongation decreased, which is the strain aging effect. The strain aging effect in the strain-based API X60 pipeline steels was minimized when the volume fraction of AF was increased and secondary phases were distributed uniformly. On the other hand, an excessively high C content formed fine precipitates, and the strain aging effect occurred because of the interactions among dislocations and fine precipitates.
- Published
- 2017
40. Priority scheduling to minimize the total tardiness for remanufacturing systems with flow-shop-type reprocessing lines
- Author
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Yi-Dong Zhou, Jong-Min Kim, and Dong-Ho Lee
- Subjects
0209 industrial biotechnology ,Engineering ,Sequence ,021103 operations research ,Job shop scheduling ,Workstation ,business.industry ,Mechanical Engineering ,Tardiness ,Real-time computing ,0211 other engineering and technologies ,Scheduling (production processes) ,02 engineering and technology ,Flow shop scheduling ,Industrial and Manufacturing Engineering ,Computer Science Applications ,Reliability engineering ,law.invention ,020901 industrial engineering & automation ,Control and Systems Engineering ,law ,Component (UML) ,business ,Remanufacturing ,Software - Abstract
This study considers the scheduling problem in remanufacturing systems in which end-of-use/life products are separated into their components at a single disassembly workstation, then each component is reprocessed at one of parallel flow-shop-type reprocessing lines, and finally the reprocessed components are reassembled into remanufactured products at parallel reassembly workstations. The problem is to determine the sequence of products to be disassembled at the disassembly workstation, the sequence of components to be reprocessed at each workstation of the reprocessing lines, and the allocation and sequence of the products to be reassembled at each reassembly workstation for a due date-based objective of minimizing the total tardiness. A mathematical programming model is developed to represent the problem, and a priority scheduling approach is proposed for practical applications. To test performances of priority rules, simulation experiments were done on various test instances, and the results are reported. In particular, we show from additional tests that the approach proposed in this study outperforms the previous one that determines reprocessing and reassembly schedules according to the sequence of disassembling products significantly, and also, the rule combination approach that uses different priority rules on disassembly, reprocessing, and reassembly shops outperforms the single rule approach that uses the same rule over the three subsystems.
- Published
- 2017
41. Value of Nonrigid Registration of Pre-Procedure MR with Post-Procedure CT After Radiofrequency Ablation for Hepatocellular Carcinoma
- Author
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Jeong Min Lee, Dong Ho Lee, Jeong Hee Yoon, Juil Park, Ijin Joo, Jin Young Park, and Ernst Klotz
- Subjects
Male ,medicine.medical_specialty ,Carcinoma, Hepatocellular ,Radiofrequency ablation ,Post-Procedure ,medicine.medical_treatment ,030218 nuclear medicine & medical imaging ,law.invention ,03 medical and health sciences ,0302 clinical medicine ,law ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,Aged ,Retrospective Studies ,Observer Variation ,Pre-Procedure ,business.industry ,Liver Neoplasms ,Palliative Care ,Ultrasound ,Margins of Excision ,Middle Aged ,medicine.disease ,Ablation ,Magnetic Resonance Imaging ,digestive system diseases ,Treatment Outcome ,surgical procedures, operative ,Liver ,030220 oncology & carcinogenesis ,Hepatocellular carcinoma ,Catheter Ablation ,Female ,Clinical Competence ,Radiology ,Tomography, X-Ray Computed ,Cardiology and Cardiovascular Medicine ,business ,therapeutics - Abstract
To evaluate the value of pre-radiofrequency ablation (RFA) MR and post-RFA CT registration for the assessment of the therapeutic response of hepatocellular carcinoma (HCC).A total of 178 patients with single HCC who received RFA as an initial treatment and had available pre-RFA MR and post-RFA CT images were included in this retrospective study. Two independent readers (one experienced radiologist, one inexperienced radiologist) scored the ablative margin (AM) of treated tumors on a four-point scale (1, residual tumor; 2, incomplete AM; 3, borderline AM; 4, sufficient AM), in two separate sessions: (1) visual comparison between pre-and post-RFA images; (2) with addition of nonrigid registration for pre- and post-RFA images. Local tumor progression (LTP) rates between low-risk (response score, 3-4) and high-risk groups (1-2) were analyzed using the Kaplan-Meier method at each interpretation session.The patients' reassignments after using the registered images were statistically significant for inexperienced reader (p 0.001). In the inexperienced reader, LTP rates of low- and high-risk groups were significantly different with addition of registered images (session 2) (p 0.001), but not significantly different in session 1 (p = 0.101). However, in the experienced reader, LTP rates of low- and high-risk groups were significantly different in both interpretation sessions (p 0.001). Using the registered images, the cumulative incidence of LTP at 2 years was 3.0-6.6%, for the low-risk group, and 18.6-27.8% for the high-risk group.Registration between pre-RFA MR and post-RFA CT images may allow better assessment of the therapeutic response of HCC after RFA, especially for inexperienced radiologists, helping in the risk stratification for LTP.
- Published
- 2017
42. Gut microbiota and butyrate level changes associated with the long-term administration of proton pump inhibitors to old rats
- Author
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Yeong-Jae Seok, Young Tae Park, Dong Ho Lee, Ji Hyun Park, Nayoung Kim, Soo In Choi, Sun Min Lee, Cheol Min Shin, Ryoung Hee Nam, and Yeon Ran Kim
- Subjects
Male ,0301 basic medicine ,medicine.medical_specialty ,lcsh:Medicine ,Firmicutes ,Butyrate ,Biology ,Gut flora ,Article ,03 medical and health sciences ,Medical research ,0302 clinical medicine ,RNA, Ribosomal, 16S ,Internal medicine ,Lactobacillus ,medicine ,Animals ,Colitis ,lcsh:Science ,Clinical microbiology ,Adverse effect ,Multidisciplinary ,lcsh:R ,Proton Pump Inhibitors ,Pseudomembranous colitis ,medicine.disease ,Commensalism ,biology.organism_classification ,Rats, Inbred F344 ,Gastrointestinal Microbiome ,Rats ,Butyrates ,030104 developmental biology ,Endocrinology ,lcsh:Q ,Enterotype ,Microbiome ,030217 neurology & neurosurgery - Abstract
The association between adverse effects of PPI and gut microbiota in old age has yet to be elucidated. We assessed changes in the gut microbiota and butyrate levels following the long-term administration of PPIs to old rats and investigated their associations. F344 aged male rats were fed a PPI-supplemented diet for 50 weeks. The ileal microbiota was analysed by metagenomic sequencing of the 16S rRNA, while the butyrate concentration was measured by high-performance liquid chromatography. We observed a significant decrease in microbial diversity following PPI administration in the 2-year-old rats but not in the 74-week-old rats. PPI treatment reduced both commensal bacteria and opportunistic pathogens, particularly in the 2-year-old rats. Enterotypes comprising the majority of the control samples were enriched in Lactobacillus, while other enterotypes in the PPI group were dominated by Turicibacter or Romboutsia. The PPI treatment reduced the butyrate concentrations in the intestines and colons of 74-week-old rats compared to the control group. The abundance of Lactobacillus significantly correlated with butyrate concentrations in 74-week-old rats. In conclusion, long-term administration of PPIs alters the gut microbiota and butyrate concentrations in rats, particularly in old age, which may be an underlying mechanism of PPI-induced adverse effects such as pseudomembranous colitis.
- Published
- 2019
43. Bubble characteristics by pressure fluctuation analysis in gas-solid bubbling fluidized beds with or without internal
- Author
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Keon Bae, Dong-Ho Lee, Jong Hun Lim, Sung-Hee Park, Dong Hyun Lee, Joo-Hee Han, and Joon-Hwan Kim
- Subjects
Range (particle radiation) ,Chemistry ,General Chemical Engineering ,Bubble ,Distributor ,Thermodynamics ,Spectral density ,02 engineering and technology ,General Chemistry ,Mechanics ,021001 nanoscience & nanotechnology ,Standard deviation ,law.invention ,Physics::Fluid Dynamics ,Pressure measurement ,020401 chemical engineering ,law ,0204 chemical engineering ,0210 nano-technology ,Particle density ,Plenum chamber - Abstract
Bubble flow characteristics were investigated in gas-solid bubbling fluidized beds (0.3 m-I.D×2.4m-high) with or without internals by power spectral analysis of absolute pressure fluctuation. Metallurgical grade silicon particles (MG-Si) were used as bed materials. The particle density and mean particle diameter were 2,328 kg/m3 and 154 μm, respectively. Absolute pressure fluctuations were measured simultaneously at two different positions: plenum chamber and beds. Absolute pressure fluctuation in the beds was measured according to the axial bed height in the range of 0.1 to 0.8m. The total sampling time of each data set was 60 s, and the sampling rate was 200Hz. Absolute pressure fluctuation data were converted to a power spectral density (PSD) by a Fast-Fourier transform (FTT) algorithm. The PSD in the beds was separated into coherent and incoherent output power. The bubble size was estimated from the standard deviation of the spectrum of incoherent output power, which occurred due to the bubble flow. The estimated bubble size determined by incoherence component analysis was compared to various empirical correlations to determine the bubble size without internals. The estimated bubble size agreed well with the correlation by Choi et al. [19]. The internals were installed 0.45 m above the distributor. With the installation of the internals, and at the bed height of 0.5m, the bubble diameter was decreased by 77% compared to the bubble without the internal at U0=0.15m/s.
- Published
- 2016
44. Hepatic stiffness measurement by using MR elastography: prognostic values after hepatic resection for hepatocellular carcinoma
- Author
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Kwang-Woong Lee, Nam-Joon Yi, Joon Koo Han, Jeong Hoon Lee, Dong Ho Lee, Jeong Min Lee, Kyung-Suk Suh, and Kyung Bun Lee
- Subjects
Adult ,Male ,medicine.medical_specialty ,Carcinoma, Hepatocellular ,Hepatic resection ,Kaplan-Meier Estimate ,Logistic regression ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,medicine ,Hepatectomy ,Humans ,Radiology, Nuclear Medicine and imaging ,Aged ,Retrospective Studies ,Receiver operating characteristic ,medicine.diagnostic_test ,business.industry ,Liver Neoplasms ,Ultrasound ,Area under the curve ,General Medicine ,Middle Aged ,Prognosis ,medicine.disease ,Magnetic resonance elastography ,ROC Curve ,Hepatocellular carcinoma ,Elasticity Imaging Techniques ,Female ,030211 gastroenterology & hepatology ,Radiology ,Elastography ,business ,Liver Failure - Abstract
To evaluate prognostic value of hepatic stiffness (HS) measurement using MR elastography (MRE) in patients with hepatocellular carcinoma (HCC) treated by hepatic resection (HR). We enrolled 144 patients with Barcelona Clinic Liver Cancer stage A HCCs initially treated by HR who underwent preoperative liver MRE between January 2010 and June 2013. HS values were measured using MRE. Receiver operating characteristics (ROC) and multivariate logistic regression analyses were used to determine significant predictive factors for posthepatecomy liver failure (PHLF). Overall survival (OS) was analyzed by evaluating prognostic factors using the Kaplan–Meier method and Cox proportional hazard regression model. After HR, 43 patients (29.9 %) experienced PHLF. HS values were significant predictive factors for PHLF. In ROC analysis, the area under the curve of HS was 0.740 (P = 0.001) for PHLF. Thirty-one patients had HS values ≥ 4.02 kPa; the estimated 1, 3, 5-year survival were 90.0 %, 74.7 % and 65.4 %, respectively, versus 98.1 %, 96.5 % and 96.5 % in 113 patients with HS values
- Published
- 2016
45. Correlation Between Microstructures and Tensile Properties of Strain-Based API X60 Pipeline Steels
- Author
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Hyoung Seop Kim, Sunghak Lee, Yunjo Ro, Chang Sun Lee, Sang Yong Shin, Dong Ho Lee, Byoungchul Hwang, and Hyokyung Sung
- Subjects
010302 applied physics ,Materials science ,Metallurgy ,Metals and Alloys ,02 engineering and technology ,Strain hardening exponent ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,01 natural sciences ,Acicular ferrite ,Volume (thermodynamics) ,Mechanics of Materials ,Ferrite (iron) ,0103 physical sciences ,Ultimate tensile strength ,Volume fraction ,Elongation ,0210 nano-technology - Abstract
The correlation between the microstructures and tensile properties of strain-based American Petroleum Institute (API) X60 pipeline steels was investigated. Eight types of strain-based API X60 pipeline steels were fabricated by varying the chemical compositions, such as C, Ni, Cr, and Mo, and the finish cooling temperatures, such as single-phase and dual-phase regions. In the 4N and 5C steels, the volume fractions of bainitic ferrite (BF) and the secondary phases increased with the increasing C and adding Cr instead of Ni. In the 5C and 6NC steels, the volume fractions of acicular ferrite (AF) and BF decreased with increasing C and adding Ni, whereas the volume fractions of polygonal ferrite (PF) and the secondary phases increased. In the 6NC and 6NM steels, the volume fraction of BF was increased by adding Mo instead of Cr, whereas the volume fractions of PF and the secondary phases decreased. In the steels rolled in the single-phase region, the volume fraction of polygonal ferrite ranged from 40 to 60 pct and the volume fraction of AF ranged from 20 to 40 pct. In the steels rolled in the dual-phase region, however, the volume fraction of PF was more than 70 pct and the volume fraction of AF was below 20 pct. The strength of the steels with a high volume fraction of AF was higher than those of the steels with a high volume fraction of PF, whereas the yield point elongation and the strain hardening exponent were opposite. The uniform elongation after the thermal aging process decreased with increasing volume fraction of PF, whereas the uniform elongation increased with increasing volume fraction of AF. The strain hardening exponent increased with increasing volume fraction of PF, but decreased with increasing volume fraction of AF and effective grain size.
- Published
- 2016
46. Is it enough to stop distal fusion at L3 in adolescent idiopathic scoliosis with major thoracolumbar/lumbar curves?
- Author
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Tae Hyung Kim, Choon Sung Lee, Chang Ju Hwang, Jung-Ki Ha, Dong Ho Lee, and Jae Hwan Cho
- Subjects
Male ,medicine.medical_specialty ,Adolescent ,Radiography ,Thoracic Vertebrae ,03 medical and health sciences ,0302 clinical medicine ,Lumbar ,Statistical significance ,medicine ,Humans ,Orthopedics and Sports Medicine ,Decompensation ,Child ,Retrospective Studies ,030222 orthopedics ,Lumbar Vertebrae ,business.industry ,Lumbar Curve ,Vertebra ,Surgery ,Spinal Fusion ,Treatment Outcome ,medicine.anatomical_structure ,Scoliosis ,Radiological weapon ,Female ,Neurosurgery ,business ,030217 neurology & neurosurgery ,Follow-Up Studies - Abstract
The choice of distal fusion level in adolescent idiopathic scoliosis (AIS) patients with major thoracolumbar or lumbar (TL/L) curves (Lenke type 3C, 5C, or 6C) remains debatable. One of the most controversial issues involves stopping the distal fusion at L3, which might result in an increased risk of decompensation but save more mobile spinal segments. The purpose of this study was to evaluate and compare the clinical and radiological outcomes of corrective surgery for AIS with major TL/L curves according to the distal fusion level. 229 AIS patients with Lenke type 3C, 5C, or 6C curves that underwent corrective surgery were included. Patients were grouped according to distal fusion level, either L3 (group A) or L4 (group B), and followed up for over 2 years. Group A was further divided into lower end vertebra (LEV) and last touching vertebra (LTV). The SRS-22 score was used to assess clinical outcomes. All radiological parameters were assessed pre- and postoperatively by standing anteroposterior whole-spine radiographs. Clinical and radiological parameters were compared between the groups. Postoperative decompensation was found in 4.6 % (9/197) of group A patients and 9.3 % (3/32) of group B patients. This difference was not statistically significant (P = 0.258). No difference was found in the clinical and radiological parameters between the two groups either pre- or postoperatively. Subgroup analysis showed that the scoliosis correction rate and postoperative apical vertebral translation were lower in cases with an LEV ≤ L4 or LTV = L5 when the fusion stopped at L3 distally. The adjacent disc wedge angle was aggravated postoperatively in these cases, although this did not reach statistical significance. There is no difference in the radiological and clinical outcomes in AIS according to the distal fusion level. Major TL/L curve correction in AIS may be sufficient distally at L3 in cases with an LEV ≥ L3 and LTV ≥ L4. However, stopping fusion at L3 requires caution in LEV ≤ L4 or LTV = L5 patients, as this correction rate might be suboptimal and causes a possible progression of the adjacent disc wedge angle.
- Published
- 2016
47. A comparison of endoscopic treatments in rectal carcinoid tumors
- Author
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Cheol Min Shin, A Young Seo, Hyun Joo Lee, Nayoung Kim, Seong Beom Kim, Dong Ho Lee, Young Soo Park, and Hyuk Yoon
- Subjects
Adult ,Male ,medicine.medical_specialty ,Endoscopic Mucosal Resection ,health care facilities, manpower, and services ,Operative Time ,Endoscopic mucosal resection ,Carcinoid Tumor ,Lower risk ,Gastroenterology ,Metastasis ,03 medical and health sciences ,0302 clinical medicine ,health services administration ,Internal medicine ,medicine ,Humans ,Endoscopy, Digestive System ,health care economics and organizations ,Aged ,Retrospective Studies ,Rectal Neoplasms ,business.industry ,Retrospective cohort study ,Odds ratio ,Middle Aged ,Hepatology ,medicine.disease ,Endoscopic Procedure ,030220 oncology & carcinogenesis ,Female ,030211 gastroenterology & hepatology ,Surgery ,Radiology ,business ,Abdominal surgery - Abstract
Various endoscopic techniques for rectal carcinoid tumors have been developed recently. In this study, we compared the outcomes of conventional endoscopic mucosal resection (EMR), strip biopsy, and EMR after circumferential precutting (EMR-P). From March 2004 to July 2014, the medical records of 188 patients (190 rectal carcinoid tumors) who were treated with an endoscopic procedure for rectal carcinoid tumors were investigated retrospectively. The characteristics of the patients and tumors, the selection of the treatment method, the rate of complete resection, and the rate of complications were analyzed retrospectively. Forty-seven, 75 and 68 cases of EMR, strip biopsy and EMR-P were performed, respectively. The mean procedure time was not significantly different between the EMR, strip biopsy and EMR-P cases (5.6, 6.5 and 7.4 min, respectively, P = 0.119). En bloc resection was achieved in most of the cases (97.8, 98.7 and 95.5 % in the EMR, strip biopsy and EMR-P cases, respectively). However, histologic examination showed positive lateral or deep resection margins in 57 out of 190 cases (30.0 %). Multivariate analysis showed that the strip biopsy and EMR-P methods were independent factors for pathologic complete resection (negative in both lateral and deep resection margins), with odds ratios for margin involvement of 0.20 and 0.43 with 95 % confidence intervals from 0.08 to 0.47 and 0.19 to 0.96, respectively. In all the follow-up cases (81 of 190, 42.6 %), no local recurrence or distal metastasis was found. Compared to conventional EMR, strip biopsy and EMR-P had a lower risk of incomplete resection. The procedure time and complication rate did not differ between the three groups, and no recurrence was detected during the follow-up period. Strip biopsy and EMR-P are safe and effective methods for the treatment of rectal carcinoid tumors.
- Published
- 2015
48. Clinicopathologic features of gastric cancer with synchronous and metachronous colorectal cancer in Korea: are microsatellite instability and p53 overexpression useful markers for predicting colorectal cancer in gastric cancer patients?
- Author
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Hee Jin Kim, Nayoung Kim, Hyung Ho Kim, Young Soo Park, Sang Hoon Ahn, Cheol Min Shin, Dong Ho Lee, Yoon Jin Choi, Hyuk Yoon, Hye Seung Lee, Il Tae Son, Sung Bum Kang, and Do Joong Park
- Subjects
Male ,Oncology ,Cancer Research ,Colorectal cancer ,Colonoscopy ,Immunoenzyme Techniques ,Neoplasms, Multiple Primary ,0302 clinical medicine ,Surgical oncology ,Aged, 80 and over ,Univariate analysis ,medicine.diagnostic_test ,Gastroenterology ,General Medicine ,Middle Aged ,Prognosis ,Adenocarcinoma, Mucinous ,Survival Rate ,Lymphatic Metastasis ,030220 oncology & carcinogenesis ,Adenocarcinoma ,Female ,Microsatellite Instability ,030211 gastroenterology & hepatology ,Colorectal Neoplasms ,Adult ,medicine.medical_specialty ,03 medical and health sciences ,Gastrectomy ,Stomach Neoplasms ,Internal medicine ,Biomarkers, Tumor ,medicine ,Humans ,Neoplasm Invasiveness ,neoplasms ,Survival rate ,Aged ,Neoplasm Staging ,Retrospective Studies ,business.industry ,Microsatellite instability ,Cancer ,medicine.disease ,digestive system diseases ,Neoplasm Grading ,Tumor Suppressor Protein p53 ,business ,Carcinoma, Signet Ring Cell ,Follow-Up Studies - Abstract
A large-scale study was performed to identify the risk factors for developing synchronous and metachronous colorectal cancer (CRC) in gastric cancer (GC) patients, including microsatellite instability (MSI) and p53 overexpression. A total of 1041 GC patients who underwent endoscopic resection or surgery and underwent colonoscopy simultaneously or during surveillance for GC were consecutively enrolled. Clinicopathologic characteristics, MSI, and p53 overexpression were compared between the GC patients with and those without synchronous and metachronous CRC. Of the 1041 patients, CRCs were detected in 67 (6.4 %) patients with GC. Forty-six (4.4 %) had synchronous CRC and 21 (2.0 %) had metachronous CRC. Univariate analysis indicated that age ≥63 years (P
- Published
- 2015
49. Increase in plasma acyl ghrelin levels is associated with abatement of dyspepsia following Helicobacter pylori eradication
- Author
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Ryoung Hee Nam, Hyun Chae Jung, Nayoung Kim, Cheol Min Shin, Ji Hyun Park, Dong Ho Lee, Yoon Jin Choi, Young Soo Park, and Hyuk Yoon
- Subjects
Adult ,Male ,medicine.medical_specialty ,Mrna expression ,Asymptomatic ,Helicobacter Infections ,03 medical and health sciences ,0302 clinical medicine ,Internal medicine ,Humans ,Medicine ,Mixed group ,Acyl ghrelin ,Dyspepsia ,Aged ,Messenger RNA ,Helicobacter pylori ,biology ,business.industry ,digestive, oral, and skin physiology ,Gastroenterology ,Middle Aged ,biology.organism_classification ,Ghrelin ,Postprandial ,Endocrinology ,Case-Control Studies ,Gastritis ,030220 oncology & carcinogenesis ,Female ,030211 gastroenterology & hepatology ,medicine.symptom ,business - Abstract
Ghrelin has been indicated as one of the etiological factors in functional dyspepsia (FD). We analyzed 179 patients with FD (based on the Rome III criteria) and 103 asymptomatic healthy individuals (controls) who had undergone endoscopy at Seoul National University Bundang Hospital from February 2011 to June 2014. FD patients were classified into three groups by means of a self-reported questionnaire: patients with postprandial distress syndrome (PDS; n = 49), patients with epigastric pain syndrome (EPS; n = 45), and patients with a combination of these two types (mixed group; n = 85). The fasting blood levels of acyl ghrelin and desacyl ghrelin and messenger RNA (mRNA) expression of preproghrelin in the fundic mucosa were measured by ELISAs and reverse transcription quantitative real-time PCR, respectively. One year after participant enrollment, they were measured again in 79 participants and the changes in the values were compared according to Helicobacter pylori eradication or symptom response. Plasma acyl ghrelin level was lower in the PDS group than in the control and EPS groups (control group 14.1 fmol/mL, PDS group 8.9 fmol/mL, EPS group 13.8 fmol/mL, mixed group 11.3 fmol/mL; P = 0.003 and P = 0.012, respectively). One year after the eradication of H. pylori, plasma acyl ghrelin level was increased and gastric preproghrelin mRNA expression was upregulated (P = 0.004 and P
- Published
- 2015
50. Effects of Finish Cooling Temperature on Tensile Properties After Thermal Aging of Strain-Based API X60 Linepipe Steels
- Author
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Yunjo Ro, Dong Ho Lee, Sang Yong Shin, Byoungchul Hwang, Hyokyung Sung, Chang Sun Lee, and Sunghak Lee
- Subjects
Cottrell atmosphere ,Materials science ,Mechanics of Materials ,Ferrite (iron) ,Martensite ,Ultimate tensile strength ,Volume fraction ,Metallurgy ,Metals and Alloys ,Strain hardening exponent ,Condensed Matter Physics ,Microstructure ,Acicular ferrite - Abstract
Two types of strain-based American Petroleum Institute (API) X60 linepipe steels were fabricated at two finish cooling temperatures, 673 K and 723 K (400 °C and 450 °C), and the effects of the finish cooling temperatures on the tensile properties after thermal aging were investigated. The strain-based API X60 linepipe steels consisted mainly of polygonal ferrite (PF) or quasi-polygonal ferrite and the volume fraction of acicular ferrite increased with the increasing finish cooling temperature. In contrast, the volume fractions of bainitic ferrite (BF) and secondary phases decreased. The tensile properties before and after thermal aging at 473 K and 523 K (200 °C and 250 °C) were measured. The yield strength, ultimate tensile strength, and yield ratio increased with the increasing thermal aging temperature. The strain hardening rate in the steel fabricated at the higher finish cooling temperature decreased rapidly after thermal aging, probably due to the Cottrell atmosphere, whereas the strain hardening rate in the steel fabricated at the lower finish cooling temperature changed slightly after thermal aging. The uniform elongation and total elongation decreased with increasing thermal aging temperature, probably due to the interactions between carbon atoms and dislocations. The uniform elongation decreased rapidly with the decreasing volume fractions of BF and martensite and secondary phases. The yield ratio increased with the increasing thermal aging temperature, whereas the strain hardening exponent decreased. The strain hardening exponent of PL steel decreased rapidly after thermal aging because of the large number of mobile dislocations between PF and BF or martensite or secondary phases.
- Published
- 2015
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