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Optimization tasks in diagnostic radiological imaging require objective quantitative metrics that correlate with the subjective perception of observers. However, although one such metric, the structural similarity index (SSIM), is popular, it has limitations across various aspects in its application to medical images. In this study, we introduce a novel image quality evaluation approach based on keypoints and their associated unique image feature values, focusing on developing a framework to address the need for robustness and interpretability that are lacking in conventional methodologies. The proposed index quantifies and visualizes the distance between feature vectors associated with keypoints, which varies depending on changes in the image quality. This metric was validated on images with varying noise levels and resolution characteristics, and its applicability and effectiveness were examined by evaluating images subjected to various affine transformations. In the verification of X-ray computed tomography imaging using a head phantom, the distances between feature descriptors for each keypoint increased as the image quality degraded, exhibiting a strong correlation with the changes in the SSIM. Notably, the proposed index outperformed conventional full-reference metrics in terms of robustness to various transformations which are without changes in the image quality. Overall, the results suggested that image analysis performed using the proposed framework could effectively visualize the corresponding feature points, potentially harnessing lost feature information owing to changes in the image quality. These findings demonstrate the feasibility of applying the novel index to analyze changes in the image quality. This method may overcome limitations inherent in conventional evaluation methodologies and contribute to medical image analysis in the broader domain., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Maruyama et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Pulmonary vein stenosis (PVS) is a serious complication of catheter ablation (CA) for atrial fibrillation (AF). PVS generally occurs several months after CA and presents with non-specific symptoms and imaging findings. There have been reports of delayed diagnoses due to a misdiagnosis as infection, interstitial pneumonia, or organizing pneumonia. We introduced six cases of PVS after CA, all of which showed narrowing of the unilateral pulmonary vessels with or without lobar volume loss in the left lung on unenhanced computed tomography. We report these findings as important results indicating the possibility of PVS after CA for AF and contributing to the early diagnosis and management of PVS.

Purpose: We aimed to examine the characteristics of imaging findings of adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) in the lungs of smokers compared with those of non-smokers., Materials and Methods: We included seven cases of AIS and 20 cases of MIA in lungs of smokers (pack-years ≥ 20) and the same number of cases of AIS and MIA in lungs of non-smokers (pack-years = 0). We compared the diameter of the entire lesion and solid component measured on computed tomography (CT) images, pathological size and invasive component diameter measured from pathological specimens, and CT values of the entire lesion and ground-glass opacity (GGO) portions between the smoker and non-smoker groups., Results: The diameters of AIS and MIA on CT images and pathological specimens of the smoker group were significantly larger than those of the non-smoker group (p = 0.036 and 0.008, respectively), whereas there was no significant difference in the diameter of the solid component on CT images or invasive component of pathological specimens between the two groups. Additionally, mean CT values of the entire lesion and GGO component of the lesions in the smoker group were significantly lower than those in the non-smoker group (p = 0.036 and 0.040, respectively)., Conclusion: AIS and MIA in smoker's lung tended to have larger lesion diameter and lower internal CT values compared with lesions in non-smoker's lung. This study calls an attention on smoking status in CT-based diagnosis for early stage adenocarcinoma., (© 2021. The Author(s).)

Objective: The aim of this study was to compare the contrast of gray to white matter between forward-projected model-based iterative reconstruction solution (FIRST) and hybrid iterative reconstruction (IR) by measuring computed tomography value of brain parenchyma., Methods: Computed tomography values of the gray and white matter in 15 areas of 21 patients (7 males, 14 females; average age, 49.5 ± 10.7 years) were measured and compared between FIRST and hybrid IR with filtered back projection (FBP) using 2 different reconstruction kernels FC21 and FC26., Results: The ratio of gray to white matter obtained using FIRST (1.25 ± 0.08) was significantly higher than that obtained using FBP with both kernel FC21 (1.13 ± 0.03) and kernel FC26 (1.22 ± 0.06)., Conclusions: FIRST increases the contrast between the gray and white matter, and decreases noise in brain computed tomography compared with FBP with hybrid IR., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Malignant tumor essentially implies structural heterogeneity. Fractal analysis of medical imaging has a potential to quantify this structural heterogeneity in the tumor AIMS: The purpose of this study is to quantify this structural abnormality in the tumor applying fractal analysis to contrast-enhanced computed tomography (CE-CT) image and to evaluate its biomarker value for predicting survival of surgically treated gastric cancer patients., Methods: A total of 108 gastric cancer patients (77 men and 31 women; mean age: 69.1 years), who received curative surgery without any neoadjuvant therapy, were retrospectively investigated. Portal-phase CE-CT images were analyzed with use of a plug-in tool for ImageJ (NIH, Bethesda, USA), and the fractal dimension (FD) in the tumor was calculated using a differential box-counting method to quantify structural heterogeneity in the tumor. Tumor FD was compared with clinicopathologic features and disease-specific survival (DSS)., Results: High FD value of the tumor significantly associated with high T stage and high pathological stage (P = 0.009, 0.007, respectively). In Kaplan-Meier analysis, patients with higher FD tumors (FD > 0.9746) showed a significantly worse DSS (P = 0.009, log rank). Multivariate analysis demonstrated that tumor FD, T stage, and N stage were independent prognostic factors for DSS. In subset analysis of lymph-node positive gastric cancers, only tumor FD was an independent prognostic factor for DSS., Conclusion: CT fractal analysis can be a useful biomarker for gastric cancer patients, reflecting survival and clinicopathologic features.

Background: Pirfenidone suppresses the decline of forced vital capacity (FVC) in patients with idiopathic pulmonary fibrosis (IPF). However, IPF progresses in some patients despite treatment. We analyzed patients with meaningful FVC declines during pirfenidone treatment and explored the factors predictive of disease progression after FVC decline., Methods: This study was a retrospective, multicenter, observational study conducted by the Okayama Respiratory Disease Study Group. We defined initial decline in %FVC as 5% or greater per 6-month period during pirfenidone treatment. IPF patients who were treated with pirfenidone and experienced an initial decline from December 2008 to September 2017 were enrolled., Results: We analyzed 21 patients with IPF. After the initial decline, 4 (19.0%) patients showed improvement in disease, 11 (52.4%) showed stable disease, and 6 (28.6%) showed progressive disease. There was no significant correlation between %FVC reduction on initial decline and subsequent %FVC change (p = 0.475). Deterioration of high-resolution computed tomography (HRCT) findings on initial decline was observed significantly more often in the progressive versus improved/stable disease groups (100% vs 20.0%, p = 0.009)., Conclusions: We revealed that deterioration of HRCT findings may predict disease progression after the initial decline in %FVC in IPF patients treated with pirfenidone., Competing Interests: Conflict of Interest The authors declare that they have no known competing financial interests., (Copyright © 2020 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.)

OBJECTIVE. The purpose of this article was to assess thin-section CT features of ciliated muconodular papillary tumors (CMPTs) of the lung and correlations between radiologic and pathologic findings. MATERIALS AND METHODS. Thin-section CT findings of 16 patients (10 men and six women; mean age, 70.7 years) with surgically resected CMPTs were retrospectively analyzed. Size, location, and internal characteristics of the tumors were evaluated. The amount of mucin in the tumors was assessed histopathologically and compared with CT findings. Tumor growth speed was calculated on the basis of size changes on thin-section CT. RESULTS. In all 16 patients, tumors were detected as a solitary pulmonary nodule. Thirteen tumors (81.3%) were located in the lower lobes, and 10 (62.5%) were adjacent to the pleura. Mean maximal diameter of the tumors was 9.1 mm (range, 6-14 mm). One tumor (6.3%) presented as a pure ground-glass nodule (GGN), seven (43.8%) as dense GGNs, and eight (50.0%) as solid nodules. Pathologically, the pure GGN and five of seven dense GGNs had a large amount of mucin, whereas seven of eight solid nodules had an intermediate or small amount of mucin. The mean annual tumor growth rate (in diameter) was 0.49 mm/y. CONCLUSION. CMPTs appear as solitary, small, and peripheral pulmonary nodules with very slow growth rates. CMPTs appearing as pure GGNs and dense GGNs tend to contain more mucin than CMPTs appearing as solid nodules.

Background: Applied research on artificial intelligence, mainly in deep learning, is widely performed. If medical images can be evaluated using artificial intelligence, this could substantially improve examination efficiency., Objective: We investigated an evaluation system for medical images with different noise characteristics using a deep convolutional neural network., Methods: Simulated computed tomography images are the targets of the system. We used an AlexNet trained with natural images for the deep convolutional neural network and a support vector machine for classification. Synthetic computed tomography images with circular and rectangular signal bodies at different levels of contrast and added Gaussian noise were used for training and testing., Results: Two transfer learning methods were tested: classification by a re-trained support vector machine using the AlexNet features, and a method that fine-tuned the deep convolutional neural network. Using the first method, all the test image noise levels could be classified correctly. The fine-tuning method achieved an accuracy rate of 92.6%., Conclusions: An image quality evaluation method using artificial intelligence will be useful for clinical images and different image quality indices in the future.

Purpose: The diagnosis and severity of chronic obstructive pulmonary disease (COPD) are defined by airflow limitation using spirometry. However, COPD has diverse clinical features, and several phenotypes based on non-spirometric data have been investigated. To identify novel phenotypes of COPD using radiologic data obtained by three-dimensional computed tomography (3D-CT)., Patients and Methods: The inner luminal area and wall thickness of third- to sixth-generation bronchi and the percentage of the low-attenuation area (less than -950 HU) of the lungs were measured using 3D-CT in patients with COPD. Using the radiologic data, hierarchical clustering was performed. Respiratory reactance and resistance were measured to evaluate functional differences among the clusters., Results: Four clusters were identified among 167 patients with COPD: Cluster I, mild emphysema with severe airway changes, severe airflow limitation, and high exacerbation risk; Cluster II, mild emphysema with moderate airway changes, mild airflow limitation, and mild dyspnea; Cluster III, severe emphysema with moderate airway changes, severe airflow limitation, and increased dyspnea; and Cluster IV, moderate emphysema with mild airway changes, mild airflow limitation, low exacerbation risk, and mild dyspnea. Cluster I had the highest respiratory resistance among the four clusters. Clusters I and III had higher respiratory reactance than Clusters II and IV., Conclusions: The 3D-CT-based radiologic phenotypes were associated with the clinical features of COPD. Measurement of respiratory resistance and reactance may help to identify phenotypic differences., Competing Interests: Hiroshi Watanabe reports grants from Japan Agency for Medical Research and Development (AMED), and consulting and lectures fees from Nippon Shinyaku and Acterion. He also received lecture fees from Bayer and Pfizer, outside the submitted work. The authors report no other conflicts of interest in this work.

Purpose: Computed tomography (CT) imaging for three-dimensional (3D) printed models may improve the quality of surgical preoperative plans. Although metal objects can cause artifacts in CT images, integration of CT and digital dental arch imaging may solve this problem. The present study aimed to evaluate effects of the number of metal restorations and mandibular position during CT imaging on accuracy of reproduced models., Methods: Stereolithography datasets from three sets of dental models having different numbers of metal restorations were obtained using a laboratory digitizing device (control) and CT equipment (nonintegrated data). CT scanning was performed under two conditions: intercuspal position (closed) and separated using paraffin wax (open). Nonintegrated data after metal artifact removal were separated into maxillary and mandibular dentition groups. The occlusal part of the control dentition and nonintegrated data were superimposed and integrated (integrated data). The root mean square (RMS) between the control and stereolithography data was calculated and analyzed with three-way analysis of variance and t-test with Bonferroni correction., Results: Increasing numbers of metal restorations resulted in increase in metal artifacts and RMS values. Moreover, the RMS of the closed dataset was significantly greater than that of the open dataset because of the creation of artificial occlusal surfaces. The RMSs of the integrated datasets were significantly smaller than those of the nonintegrated datasets, except for the open model without metal restorations., Conclusions: Accuracies of reproduced maxillary and mandibular models decreased with increasing numbers of metal restorations and in the closed mandibular position during CT scanning., (Copyright © 2019 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.)

In this study, computer simulations and experiments were used to verify the accuracy of a two-dimensional image registration program (program) for portal images that we previously developed. The program used a computed radiography cassette system and digitally reconstructed radiography images as planning images for external beam radiation therapy. Using this program, we also investigated the reason two-dimensional automatic image registration images experienced large misregistration in clinical practice using commercial image registration systems. Mutual information and normalized mutual information were used as the registration criteria. To investigate the influence of image background with or without a region of interest (ROI), results of image registrations were compared. Parameters of image registration were defined as translation in the horizontal and vertical directions (x and y, respectively) and rotation (θ) around the axis perpendicular to the x-y plane. There was no significant difference in image registration arising from the difference between mutual information and normalized mutual information. Image registration was improved with a ROI. Regardless of the registration criteria, errors in image registration with a ROI in the experimental study were ≤1.2 mm in directions x and y and ≤1.0 degree in rotation θ. We found that image registration required setting up as close to the planned position as possible.

Fraction of exhaled nitric oxide (FeNO) provides information about chronic inflammation in asthma. However, its relationship with structural changes in the airways is unknown. We aimed to evaluate the correlation between computer-based airway changes and FeNO in patients with asthma. The wall area (WA) and airway inner luminal area (Ai) of the third- to sixth-generation bronchi were measured using three-dimensional computed tomography in asthmatic patients. Each value was corrected by body surface area (BSA). Relationships between FeNO and WA/BSA and Ai/BSA were evaluated. Forty-one clinically stable patients with asthma were evaluated. FeNO was significantly correlated with WA/BSA of the third-, fourth-, fifth- and sixth-generation bronchi (Spearman correlation coefficient (ρ) = 0.326, p = 0.041; ρ = 0.356, p = 0.025; ρ = 0.496, p = 0.002; and ρ = 0.529, p < 0.001, respectively). The correlation with sixth-generation bronchi was significantly greater than with the third-generation bronchi (p = 0.047). Partial rank correlation analysis indicated FeNO was significantly correlated with WA/BSA of the sixth-generation bronchi, independent from confounding factors of Ai/BSA, age, duration of asthma, dose of inhaled corticosteroid, blood eosinophil percentage, and blood IgE (ρ = 0.360, p = 0.034). In contrast, there was no correlation between FeNO and Ai/BSA. FeNO correlates with bronchial wall thickening in asthma patients. Measurement of FeNO may be useful to detect airway remodeling in asthma.

The goal of this study is to develop a more appropriate shielding calculation method for computed tomography (CT) in comparison with the Japanese conventional (JC) method and the National Council on Radiation Protection and Measurements (NCRP)-dose length product (DLP) method. Scattered dose distributions were measured in a CT room with 18 scanners (16 scanners in the case of the JC method) for one week during routine clinical use. The radiation doses were calculated for the same period using the JC and NCRP-DLP methods. The mean (NCRP-DLP-calculated dose)/(measured dose) ratios in each direction ranged from 1.7 ± 0.6 to 55 ± 24 (mean ± standard deviation). The NCRP-DLP method underestimated the dose at 3.4% in fewer shielding directions without the gantry and a subject, and the minimum (NCRP-DLP-calculated dose)/(measured dose) ratio was 0.6. The reduction factors were 0.036 ± 0.014 and 0.24 ± 0.061 for the gantry and couch directions, respectively. The (JC-calculated dose)/(measured dose) ratios ranged from 11 ± 8.7 to 404 ± 340. The air kerma scatter factor κ is expected to be twice as high as that calculated with the NCRP-DLP method and the reduction factors are expected to be 0.1 and 0.4 for the gantry and couch directions, respectively. We, therefore, propose a more appropriate method, the Japanese-DLP method, which resolves the issues of possible underestimation of the scattered radiation and overestimation of the reduction factors in the gantry and couch directions.

Objective: The defect volume measured on computed tomography (CT) for secondary bone graft (SBG) is well correlated to the actual amount of particulate cancellous bone and marrow (PCBM) transplanted in unilateral cleft lip and palate (UCLP) patients. However, the validity of such measurements have not been completely verified due to lack of evaluation of treatment results. The objective of this study was to propose an estimation method by CT based on the data of successfully treated patients. For this purpose, the association was initially verified between the weight of transplanted PCBM and the defect volume measured on CT using the results of successfully treated patients., Methods: Treatment results were evaluated 1 year after SBG by intraoral radiography in 50 UCLP patients. For the patients with good results, the correlation was investigated between the defect volume on CT and the transplanted PCBM weight, and a method was proposed based on PCBM density, calculated as PCBM weight divided by defect volume on CT., Results: In successfully treated patients showing level 3 or 4 alveolar resorption, a strong correlation (r = .87) was found between the volume on CT and the PCBM weight. Level 4 results were observed in 22 of 23 (95.7%) patients who had calculated PCBM densities of more than 6 g/cm 3 ., Conclusions: Volume estimation on preoperative CT was confirmed to have sufficient validity. The weight of PCBM transplanted should be greater than the defect volume on CT multiplied by 6.

Objectives: The purpose of this study was to investigate whether CT/MRI fusion volumetric images can improve the detectability of the mandibular canal (MC) compared with CT alone., Methods: Images of 31 lesions within or close to the mandible using both multislice CT (MSCT) and MRI were gathered from our imaging archives. All lesions underwent MSCT and three-dimensional volumetric interpolated breath-hold examination (3D-VIBE) MRI. Of the 62 hemimandibles, 13 hemimandibles were excluded because the MC passed through a lesion. The remaining 49 hemimandibles were included in this study. Each hemimandible was divided into 3 areas (premolar, molar and retromolar), and 147 areas were evaluated. First, the visibility of the MC on CT or its neurovascular bundle (NVB) on 3D-VIBE was evaluated. Second, in areas in which both the MC and NVB were visible, the relative locations of the NVB on MRI and the position of the MC on CT were assessed using CT/MRI fusion volumetric images., Results: The MC and NVB were clearly visible in 100 (68%) and 144 (98%) of 147 areas on CT and MRI, respectively. All NVBs and MCs were in identical locations, and the NVB on MRI was the same size or smaller than the MC on CT in 79 and 21 areas, respectively., Conclusions: 3D-VIBE MRI can accurately depict the NVB. Compared with CT alone, CT/MRI fusion volumetric imaging improves MC detectability.

The forced oscillation technique provides information concerning respiratory impedance, which comprises resistance and reactance of the respiratory system. However, its relationship with morphological changes of the lungs in chronic obstructive pulmonary disease (COPD) remains unclear. Respiratory impedance and spirometric data were evaluated in 98 patients with COPD and 49 reference subjects. Wall thickness (WT) and airway intraluminal area (Ai) of third- to sixth-generation bronchi, and percentage low-attenuation area with less than -950 HU (%LAA) of lungs were measured using three-dimensional computed tomography. COPD patients had higher respiratory impedance, decreased Ai, and increased %LAA compared with reference subjects. Indices of respiratory resistance and reactance and forced expiratory volume in 1 second (FEV 1 ) were correlated with Ai, and the association between percent predicted FEV 1 and Ai was predominant in distal bronchi. The difference in respiratory resistance between 5 Hz and 20 Hz (R5-R20) and FEV 1 /forced vital capacity ratio (FEV 1 /FVC) were correlated with WT. The %LAA was correlated with the FEV 1 /FVC ratio and respiratory reactance. Airway function measurements with the forced oscillation technique provide complementary information to spirometry in COPD., Competing Interests: The authors declare no competing financial interests.

The purpose of this study was to develop a consensus-based computed tomographic (CT) atlas that defines lymph node stations in radiotherapy for lung cancer based on the lymph node map of the International Association for the Study of Lung Cancer (IASLC). A project group in the Japanese Radiation Oncology Study Group (JROSG) initially prepared a draft of the atlas in which lymph node Stations 1-11 were illustrated on axial CT images. Subsequently, a joint committee of the Japan Lung Cancer Society (JLCS) and the Japanese Society for Radiation Oncology (JASTRO) was formulated to revise this draft. The committee consisted of four radiation oncologists, four thoracic surgeons and three thoracic radiologists. The draft prepared by the JROSG project group was intensively reviewed and discussed at four meetings of the committee over several months. Finally, we proposed definitions for the regional lymph node stations and the consensus-based CT atlas. This atlas was approved by the Board of Directors of JLCS and JASTRO. This resulted in the first official CT atlas for defining regional lymph node stations in radiotherapy for lung cancer authorized by the JLCS and JASTRO. In conclusion, the JLCS-JASTRO consensus-based CT atlas, which conforms to the IASLC lymph node map, was established., (© The Author 2016. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.)

Purpose: To determine the iodine load per body weight (ILPBW) that is minimally required for the detection of pancreatic adenocarcinoma for 80kVp CT imaging., Material and Methods: Institutional review board approval and written informed consent were obtained. Fifty-seven consecutive patients with histopathologically-proven pancreatic adenocarcinoma were assigned to three groups at random according to iodine load (0.5, 0.4, and 0.3gI/kg) and underwent CT at 80kVp. Enhancement of the pancreas and visualization of the tumor were assessed during the pancreatic parenchymal-phase and compared among the three groups. The relationship between the iodine load and tumor conspicuity was also analyzed., Results: The mean CT number of the pancreas (HUpancreas) was higher in the 0.5gI/kg group (158.8HU) than in the 0.4 (121.7HU) and 0.3 (106.6HU) gI/kg groups (P<0.05). Tumor-to-pancreas contrast (HUtumor-to-pancreas) was also higher in 0.5gI/kg group (88.9HU) than in 0.4 (62.2HU) and 0.3 (54.5HU) gI/kg groups (P<0.05). Linear regression between HUpancreas or HUtumor-to-pancreas and ILPBW were expressed as HUpancreas=23.3+263.9×ILPBW (r=0.74, P<0.0001) and HUtumor-to-pancreas=-1.24+174.3×ILPBW (r=0.56, P<0.0001), respectively. The iodine load estimated to achieve an acceptable HUpancreas (>100HU) and HUtumor-to-pancreas (>50HU) were 0.29 and 0.30gI/kg, respectively., Conclusion: An iodine load of 0.3gI/kg was the least amount required for the detection of pancreatic adenocarcinoma at 80kVp CT., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Purpose: To prospectively determine the feasibility of low-iodine-load and low-tube-voltage computed tomographic (CT) angiographic imaging of the kidney and to evaluate the opacification and image quality compared with moderate-iodine-load and high-iodine-load techniques., Materials and Methods: Institutional review board approval and written informed consent was obtained. One hundred thirteen consecutive patients randomly underwent three protocols for dual-phase renal CT angiographic imaging: high-iodine-load (600 mg iodine per kilogram of body weight at 120 kVp); moderate-iodine-load (400 mg iodine per kilogram of body weight at 80 kVp); and low-iodine-load (contrast agent injection initially prepared at 400 mg iodine per kilogram of body weight but stopped immediately after bolus-tracking trigger at 80 kVp) scanning. CT numbers of vessels and kidneys were measured. CT numbers and signal-to-noise ratio (SNR) were compared with one-way analysis of variance and posthoc Tukey-Kramer test and depiction of vessels and image noise, with Kruskal-Wallis test and pair-wise Mann-Whitney test with Bonferroni correction., Results: Mean iodine weight administered was significantly reduced in order of low- (16.4 g), moderate- (23.5 g), and high-iodine-load (33.7 g) protocols (P < .001). Mean CT numbers of abdominal aorta, renal artery, and renal cortex in first phase were significantly lower with high-iodine-load protocol (308, 274, and 132 HU, respectively) than with moderate- (347, 334, and 156 HU, respectively; P = .001-.006) or low-iodine-load (362, 316, and 161 HU, respectively; P = .001-.003) protocol. Mean CT number of renal vein in second phase was significantly lower with low-iodine-load protocol (223 HU) than with moderate- (299 HU; P < .001) or high-iodine-load (258 HU; P = .020). Mean SNR of renal medulla in second phase was significantly lower (P = .019) with moderate-iodine-load protocol (mean SNR, 7.2) than with high-iodine-load protocol (mean SNR, 10.0). No significant difference in image quality grades was found between high-iodine-load (mean grade, 2.6-2.9), moderate-iodine-load (mean grade, 2.6-3.0), and low-iodine-load (mean grade, 2.6-2.9) protocols (P = .018-.31)., Conclusion: Combined application of low-iodine-load, bolus tracking with saline flushing, and low-tube-voltage scanning is feasible and resulted in substantial reduction of iodine dose for renal CT angiographic imaging without compromising image quality., (RSNA, 2014)

Patients with severe internal carotid artery (ICA) stenosis with multiple medical problems generally undergo carotid artery stenting (CAS). However, it is difficult to perform CAS in some patients because iodinated contrast medium is hard to use. We report a patient with asymptomatic ICA stenosis and chronic renal failure, in whom successful treatment was achieved using CAS with minimal use of iodinated contrast medium. A 68-year-old man with severely chronic renal failure was consulted for treatment of left ICA stenosis. Magnetic resonance angiography (MRA) and carotid echography revealed left ICA severe stenosis, and systemic non-contrast MRA showed left femoral artery constriction, but right femoral artery to be intact. CAS was therefore performed through the right femoral artery, using non-contrast three-dimensional computed tomography (3D-CT) with MRA fusion imaging, intravascular ultrasonography, and a small amount of iodinated low-osmolar contrast medium. Postoperative course was uneventful with no aggravation of renal dysfunction, and he was discharged 7 days postoperatively. These techniques are very useful for patients with chronic renal failure, and this present case represents the first report of CAS treated by using non-contrast 3D-CT with MRA fusion image technique., (© The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.)

Background: Detailed reports on mucinous adenocarcinoma (formerly "mucinous bronchioloalveolar carcinoma") have not been published. We evaluated the correlation between thin-section computed tomography findings and the clinicopathologic characteristics and prognosis of mucinous adenocarcinoma., Methods: From April 1997 to March 2008, 45 resected lung carcinomas were diagnosed as mucinous adenocarcinoma. Five cases of multiple lung cancers or ambiguous mucinous adenocarcinoma were excluded. Tumors were classified as "solitary-type" or "pneumonic-type" tumors according to the thin-section computed tomography findings. We evaluated the clinicopathologic characteristics and the epidermal growth factor receptor and KRAS gene mutation statuses and correlated the thin-section computed tomography findings with patient prognoses., Results: Thirty patients had solitary-type and 10 had pneumonic-type tumors. The lesions in 23, 14, and 3 patients were classified as pathologic stage I, stage II, and stage III, respectively. Five patients had adenocarcinoma in situ, 9 had minimally invasive adenocarcinoma, and 26 had invasive mucinous adenocarcinoma. Thirteen patients showed recurrences, which were classified as intrapulmonary metastases in all patients. The 5-year overall and relapse-free survival rates were 83.3% and 88.8%, respectively, in patients with solitary-type tumors and 20.0% and 0%, respectively, in patients with pneumonic-type tumors (p < 0.001). The median follow-up time for surviving patients was 81 months. KRAS mutations were detected in 30 patients, but epidermal growth factor receptor mutations were absent in all patients., Conclusions: Our results indicated that thin-section computed tomography findings for mucinous adenocarcinoma were useful in predicting prognosis before surgical resection. Further studies are required to improve the treatment strategy for mucinous adenocarcinoma., (Copyright © 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)

Purpose: To prospectively assess the effect of reduced iodine load to contrast enhancement, image quality, and detectability of hepatocellular carcinomas (HCCs) in hepatic CT with a combination of 80 kVp tube voltage setting and adaptive statistical iterative reconstruction (ASIR) technique in patients with chronic liver disease., Materials and Methods: This HIPAA-compliant study was approved by our institutional review board and written informed consent was obtained in all patients. During a recent 9-month period, 170 consecutive patients (114 men and 56 women; age range, 40-85 years; mean, 67.7 years) with suspected chronic liver diseases were randomized into three CT groups according to the following iodine-load and tube-voltage protocols: 600 milligram per kilogram body weight (mg/kg) iodine load and 120 peak kilovolt (kVp) tube voltage setting (600-120 group), 500 mg/kg and 80 kVp (500-80 group), and 400mg/kg and 80 kVp (400-80 group). Analysis of variance was conducted to evaluate differences in CT number, background noise, signal-to-noise ratio (SNR), effective dose, HCC-to-liver contrast-to-noise ratio (CNR), and figure of merit (FOM). Sensitivity, specificity, and area under the receiver-operating-characteristic curve (AUC) were compared to assess the detectability of HCCs., Results: Vascular and hepatic enhancement in the 400-80 and 500-80 groups was comparable to or greater than that in the 600-120 group (P<.05). Subjective image quality was comparable among the three groups. Sensitivity, specificity, and AUC for detecting HCCs were comparable among the groups. The effective dose was kept low (3.3-4.1 mSv) in all three groups., Conclusion: Iodine load can be reduced by 33% in CT of the liver with a combination of 80 kVp tube voltage setting and ASIR technique, without compromising the contrast enhancement, image quality, and detection of HCCs., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

We here describe the radiologic findings of peritoneal chronic abscess formation due to gallstones lost within the peritoneum during laparoscopic cholecystectomy (LC). A radiologic workup 7 months after LC revealed a soft-tissue mass with contrast enhancement, harboring internal necrosis and punctate calcium located in the Morrison's pouch. The mass exhibited restricted water molecule diffusion, absence of fat deposition, and increased F-18 fluorodeoxy-D-glucose uptake, thus mimicking a malignant tumor. The biopsy revealed an inflammatory granuloma. Another patient with similar findings was treated with percutaneous abscess drainage. Thus, radiologists should be aware of this disease condition and its imaging findings., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Purpose: To prospectively assess the contrast enhancement, image quality, radiation dose, and detectability of malignant pancreatic tumors with pancreatic computed tomography (CT) obtained at an 80-kilovolt (peak) (kV[p]) tube voltage setting and reduced iodine dose., Methods: Institutional review board approval and written informed consent were obtained. During a recent 10-month period, 136 patients (66 men and 70 women; age range, 21-86 years; mean ± SD age, 65.9 ± 11.0 years) with suspected pancreatic disease were randomized into 3 groups according to the following iodine-load and tube-voltage protocols: 600 mg of iodine per kilogram body weight (mg/kg) and 120 kV(p) (600-120 group), 500 mg/kg and 80 kV(p) (500-80 group), and 400 mg/kg and 80 kV(p) (400-80 group). Analysis of variance was conducted to evaluate differences in CT number, background noise, signal-to-noise ratio, effective dose, lesion-to-pancreas contrast-to-noise ratio, and figure of merit. Sensitivity, specificity, and area under the receiver-operating-characteristic curve were compared to assess the detectability of malignant pancreatic tumors., Results: The signal-to-noise ratios in vessels were greater (P < 0.05) in the 400-80 and 500-80 groups than in the 600-120 group, and those in pancreas were comparable between the 400-80 and 600-120 groups. No significant difference was found in effective dose, image quality, lesion-to-pancreas contrast-to-noise ratio, or figure of merit between the groups. Sensitivity, specificity, and area under the receiver-operating-characteristic curve for detecting malignant pancreatic tumors were comparable between the groups., Conclusions: Pancreatic CT with an 80-kV(p) setting and 400-mg iodine per kilogram contrast material load facilitates the reduction of iodine dose while maintaining image quality and the detectability of malignant pancreatic tumors.

Introduction: The purpose of this study was to assess computed tomography (CT) and magnetic resonance (MR) imaging findings of salivary gland tumors of the parotid gland with emphasis on intratumoral cystic components., Methods: Seventy-two histopathologically confirmed salivary gland tumors of the parotid gland (44 benign and 28 malignant), which underwent both CT and MR imaging including contrast-enhanced study, were included in this study. We retrospectively reviewed images for the presence, number, occupying rate, margin characteristics, distribution, and predominant MR signal intensity of intratumoral cystic components., Results: The prevalence of cystic components was greater in malignant than benign tumors (79 vs. 50%, p < 0.05). The number and occupying rate were similar between benign and malignant tumors. The irregular margins were more frequent in malignant than benign tumors (73 vs. 27%, p < 0.01). The frequency of eccentric location was greater in benign than malignant tumors (91 vs. 55%, p < 0.01), whereas the frequency of centric location was greater in malignant than benign tumors (32 vs. 0%, p < 0.01). On T1-weighted images, the frequency of hyperintensity was greater in benign than malignant tumors (50 vs. 9%, p < 0.01), whereas that of isointensity was greater in malignant than benign tumors (50 vs. 0%, p < 0.01). Multiple logistic regression analysis showed that the absence of irregular margins of cystic components only was significantly correlated with the presence of benign salivary gland tumors (p < 0.01)., Conclusion: Imaging features of intratumoral cystic components may help to differentiate benign from malignant tumors of the parotid salivary gland.

Purpose: To perform volumetric analysis of stage I lung adenocarcinomas by using an automated computer program and to determine value of volumetric computed tomographic (CT) measurements associated with prognostic factors and outcome., Materials and Methods: Consecutive patients (n = 145) with stage I lung adenocarcinoma who underwent surgery after preoperative chest CT were enrolled. By using volumetric automated computer-assisted analytic program, nodules were classified into three subgroups: pure ground glass, part solid, or solid. Total tumor volume, solid tumor volume, and percentage of solid volume of each cancer were calculated after eliminating vessel components. One radiologist measured the longest diameter of the solid tumor component and of total tumor with their ratio, which was defined as solid proportion. The value of these quantitative data by examining associations with pathologic prognostic factors and outcome measures (disease-free survival and overall survival) were analyzed with logistic regression and Cox proportional hazards regression models, respectively. Significant parameters identified at univariate analysis were included in the multiple analyses., Results: All 22 recurrences occurred in patients with nodules classified as part solid or solid. Multiple logistic regression analysis revealed that percentage of solid volume of 63% or greater was an independent indicator associated with pleural invasion (P = .01). Multiple Cox proportional hazards regression analysis revealed that percentage of solid volume of 63% or greater was a significant indicator of lower disease-free survival (hazard ratio, 18.45 [95% confidence interval: 4.34, 78.49]; P < .001). Both solid tumor volume of 1.5 cm(3) or greater and percentage of solid volume of 63% or greater were significant indicators of decreased overall survival (hazard ratio, 5.92 and 9.60, respectively [95% confidence interval: 1.17, 30.33 and 1.17, 78.91, respectively]; P = .034 and .036, respectively)., Conclusion: Two volumetric measurements (solid volume, ≥1.5 cm(3); percentage of solid volume, ≥63%) were found to be independent indicators associated with increased likelihood of recurrence and/or death in patients with stage I adenocarcinoma.

Background and Purpose: Muscle atrophy is generally mild in patients with chronic inflammatory demyelinating polyneuropathy (CIDP) compared with the severity and duration of the muscle weakness. Muscle atrophy was evaluated using computed tomography (CT) in patients with CIDP., Methods: Thirty-one patients with typical CIDP who satisfied the diagnostic criteria for the definite CIDP classification proposed by the European Federation of Neurological Societies and the Peripheral Nerve Society were assessed. The clinicopathological findings in patients with muscle atrophy were also compared with those in patients without atrophy., Results: Computed tomography evidence was found of marked muscle atrophy with findings suggestive of fatty degeneration in 11 of the 31 patients with CIDP. CT-assessed muscle atrophy was in the lower extremities, particularly in the ankle plantarflexor muscles. Muscle weakness, which reflects the presence of muscle atrophy, tended to be more pronounced in the lower extremities than in the upper extremities in patients with muscle atrophy, whereas the upper and lower limbs tended to be equally affected in patients without muscle atrophy. Nerve conduction examinations revealed significantly greater reductions in compound muscle action potential amplitudes in the tibial nerves of patients with muscle atrophy. Sural nerve biopsy findings were similar in both groups. The functional prognoses after immunomodulatory therapies were significantly poorer amongst patients with muscle atrophy., Conclusions: Muscle atrophy was present in a subgroup of patients with CIDP, including patients with a typical form of the disease. These patients tended to demonstrate predominant motor impairments of the lower extremities and poorer functional prognoses., (© 2014 The Author(s) European Journal of Neurology © 2014 EFNS.)

Purpose: The purpose of this study was to compare the diagnostic accuracies of CT and MR imaging for the detection of metastatic retropharyngeal lymph nodes (RLNs) in patients with nasopharyngeal and oropharyngeal squamous cell carcinoma (SCC)., Materials and Methods: The study included 38 patients (28 men and 10 women; mean age, 65 years; age range, 48-82 years) with nasopharyngeal (n=15) and oropharyngeal (n=23) SCC who underwent both contrast-enhanced CT and MR imaging before chemoradiotherapy. RLNs were classified as malignant or benign on the basis of the results of follow-up MR imaging. Two radiologists independently evaluated the images for diagnosing metastatic RLNs., Results: Among a total of 68 RLNs (minimum diameter, ≥ 4 mm) that were detected on gadolinium-enhanced fat-suppressed T1-weighted images, 30 (44%) were malignant and 38 (56%) were benign. The sensitivities of CT versus MRI were 60% versus 97% for observer 1 (p<0.01) and 37% versus 90% for observer 2 (p<0.01). The specificities of CT versus MRI were 92% versus 97% for observer 1 (p=0.50) and 92% versus 100% for observer 2 (p=0.25). The areas under the receiver operating characteristic curve (AUC) for CT versus MRI were 0.788 versus 0.996 for observer 1 (p<0.01) and 0.693 versus 0.961 for observer 2 (p<0.01)., Conclusion: MR imaging was superior to CT for the detection of metastatic RLNs., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

Purpose: To assess the optimal scan delays and contrast injection durations for contrast-enhanced whole-body computed tomography (CT)., Materials and Methods: One hundred forty-two patients were randomized into three groups: protocol A-scan delay of 65 s after starting contrast injection over 30 s; protocol B-105 and 70 s; and protocol C-145 and 110 s, respectively. Contrast enhancement and diagnostic acceptability were assessed., Results: Qualitative assessment was subtle among the three protocols. Homogenous enhancement of deep veins was more assuredly achieved with protocol C., Conclusion: With protocol C, qualitatively acceptable enhancement can be obtained in whole-body CT., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Purpose: Modeling the postmortem liver for autopsy imaging is a challenging problem owing to the variation in organ deformation found in cadavers and limited availability of postmortem liver CT scans. An algorithm was developed to construct a statistical shape model (SSM) for the adult postmortem liver in autopsy imaging., Methods: First, we investigated the relationship between SSMs obtained from in vivo liver CT scans and those from postmortem cases. Liver shapes were embedded in level set functions and statistically modeled using a spatially weighted principal components analysis. The performance of the SSMs was evaluated in terms of generalization and specificity. Several algorithms for the transformation from in vivo livers to postmortem livers were proposed to enhance the performance of an SSM for a postmortem liver, followed by a comparative study on SSMs. Specifically, five SSMs for a postmortem liver were constructed and evaluated using 32 postmortem liver labels, and postmortem liver labels synthesized from 144 in vivo liver labels were constructed using the proposed transformation algorithms. We also compared the proposed SSMs with three conventional SSMs trained from postmortem liver labels and/or in vivo liver labels., Results: The investigation showed that the performance of an SSM constructed using in vivo liver labels suffered when describing postmortem liver shapes. Two of the five proposed SSMs trained using synthesized postmortem livers showed the best performance with no significant differences between them, and they statistically outperformed all conventional SSMs tested., Conclusions: The performance of conventional SSMs can be improved by using both postmortem liver shape labels and artificial shape labels synthesized from in vivo liver shape labels.

Objective: The purpose of this study was to prospectively evaluate the contrast enhancement, vascular depiction, image quality, and radiation dose of low-tube-voltage whole-body CT angiography (CTA) performed with low-concentration iodinated contrast material., Subjects and Methods: Whole-body CTA was performed on 109 patients with a 64-MDCT scanner. Patients were randomized into three groups: CTA with 240-mg/mL contrast material at 80 kVp (240-80 group), 300-mg/mL at 80 kVp (300-80 group), and 370-mg/mL at 120 kVp (370-120 group). Signal-to-noise ratio (SNR), arterial depiction, image quality, and radiation dose were assessed. Figure of merit was computed to normalize signal-to-noise ratio, estimated effective dose, and iodine weight., Results: In the 240-80 group, the mean load of administered iodine was 21.6 g; for the 300-80 group, 26.8 g; and the 370-120 group, 34.0 g (p < 0.05). The ranges of mean vascular enhancement were 508-521 HU, 546-593 HU, and 435-442 HU (p < 0.05). Arterial depiction and image quality were comparable for the 240-80 and 370-120 groups and were greater for the 300-80 group than the other two groups in selected arteries (p < 0.05). Effective dose was higher (p < 0.05) in the 370-120 group (2.8-5.4 mSv) than in the others (2.3-4.3 mSv). The figure of merit in the 240-80 group was greater than (p < 0.05) or comparable to that in the 370-120 group., Conclusion: Use of 240-mg/mL contrast material at 80 kVp seems appropriate for routine whole-body CTA and beneficial for reduction of iodine load and radiation dose, whereas use of 300-mg/mL contrast material may marginally improve delineation of selected small arteries.

This paper presents a novel conditional statistical shape model in which the condition can be relaxed instead of being treated as a hard constraint. The major contribution of this paper is the integration of an error model that estimates the reliability of the observed conditional features and subsequently relaxes the conditional statistical shape model accordingly. A three-step pipeline consisting of (1) conditional feature extraction from a maximum a posteriori estimation, (2) shape prior estimation through the novel level set based conditional statistical shape model with integrated error model and (3) subsequent graph cuts segmentation based on the estimated shape prior is applied to automatic liver segmentation from non-contrast abdominal CT volumes. Comparison with three other state of the art methods shows the superior performance of the proposed algorithm., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Purpose: To investigate the best standardized uptake value (SUV) index for differentiation of adrenal metastases from adrenocortical adenomas using 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT)., Materials and Methods: A total of 129 patients (82 males and 47 females; mean age 65.4 years) with extra-adrenal primary malignancies who had known or suspected adrenal lesions underwent FDG PET/CT examinations for detection, staging, re-staging, or recurrence of tumor. Among these patients, 45 adrenal lesions (22 adenomas and 23 metastases) in 41 patients were evaluated. The maximum SUVs for adrenal lesions (adrenal SUVmax) and mean liver and spleen SUVs were recorded, and the ratio of the adrenal SUVmax to the mean liver SUV (adrenal-to-liver SUV ratio) and that of the adrenal SUVmax to the mean spleen SUV (adrenal-to-spleen SUV ratio) were obtained. Diagnostic performances for the adrenal SUVmax, adrenal-to-liver SUV ratio, and adrenal-to-spleen SUV ratio were compared., Results: The mean adrenal SUVmax, adrenal-to-liver SUV ratio, and adrenal-to-spleen SUV ratio were higher for adrenal metastases (8.4 ± 3.8, 3.0 ± 1.3, and 4.0 ± 1.9, respectively) than for adrenocortical adenomas (2.9 ± 1.0, 0.9 ± 0.3, and 1.3 ± 0.3, respectively) (P < 0.001). The area under the curve was higher for the adrenal-to-liver SUV ratio (0.99) than for the adrenal SUVmax (0.96) and adrenal-to-spleen SUV ratio (0.98). In the differentiation of adrenocortical adenomas and adrenal metastases, an adrenal-to-liver SUV ratio cutoff value of 1.37 yielded a sensitivity of 96% and specificity of 100%., Conclusion: In FDG PET/CT analysis, the adrenal-to-liver SUV ratio had a greater ability to differentiate adrenocortical adenomas and adrenal metastases than did the adrenal SUVmax or adrenal-to-spleen SUV ratio.

Objective: To compare total body weight (TBW), lean body weight (LBW) and body surface area (BSA) for the adjustment of the iodine dose required for contrast-enhanced multi-detector computed tomography (MDCT) of the aorta and the liver., Methods: One hundred and three patients undergoing MDCT of the abdomen were randomised into three groups: the TBW group receiving 0.6 g iodine/kg of TBW (n = 33), the LBW group receiving 0.75 g iodine/kg of LBW (n = 35) and the BSA group receiving 22 g iodine/m(2) (n = 35). ∆HU (increases in CT value) per gram of iodine (∆HU/g) and adjusted maximum hepatic enhancement (adjusted MHE; ∆HU/[g iodine/kg]) correlated with three groups using linear regressions., Results: Correlation coefficients of ∆HU/g were 0.67 (TBW), 0.86 (LBW) and 0.85 (BSA) for the aorta, and 0.74 (TBW), 0.77 (LBW) and 0.84 (BSA) for the liver. Adjusted MHE was constant at 70.2 with LBW and at 2.69 with BSA, but correlated positively with TBW (r = 0.58, P < 0.001)., Conclusion: Iodine load may need to be tailored by LBW or BSA in contrast enhanced MDCT of the abdomen. BSA is a simple and feasible index for the determination of iodine dose in individual patients., Key Points: • Optimisation of enhancement is very important for high quality MDCT. • Iodine dose is best adjusted according to LBW or BSA. • BSA may be adopted because calculation is simple. • Iodine dose of 0.712 g/kg LBW/18.6 g/m (2) BSA gives 50 HU hepatic enhancement.

Purpose: To compare vascular measurements to determine stent types and configurations for abdominal endovascular aneurysm repair (EVAR) by comparing results of contrast material-enhanced computed tomographic (CT) angiography and nonenhanced magnetic resonance (MR) angiography., Materials and Methods: This prospective study was institutional review board approved, and all patients provided written informed consent. Fifty patients (45 men and five women; mean age, 76.0 years) admitted for elective abdominal EVAR underwent preoperative abdominal CT angiography (triplanar reformatted images; section thickness of 1-3 mm) and nonenhanced MR angiography (triplanar two-dimensional single-shot turbo field-echo images; section thickness of 6 mm). Two observers independently completed standard measurement and device selection forms for endovascular stent planning for CT and MR angiography. Pearson and intraclass correlation coefficients were calculated to evaluate intermodality and interobserver differences., Results: No significant difference was found in aortic neck diameter (observer 1: CT, 18.5 mm; MR, 19.0 mm; P = .43) (observer 2: CT, 19.6 mm; MR, 19.3 mm; P = .59), aortic neck diameter 15 mm distal to the lowest renal artery (observer 1: CT, 19.2 mm; MR, 19.2 mm; P = .38) (observer 2: CT, 19.6 mm; MR, 19.6 mm; P = .91), aortic neck length (observer 1: CT, 43.6 mm; MR, 43.6 mm; P = .85) (observer 2: CT, 44.4 mm; MR, 44.0 mm; P = .93), or other key vascular measurements (P = .23-.99) for preoperative planning. These included aneurysm diameter, lowest renal artery to aortic bifurcation length, aortic bifurcation diameter, common iliac artery diameters, external iliac artery diameters, length between orifices of lower renal and internal iliac arteries, and iliac artery sealing length. CT and MR angiography measurements showed very strong correlation (r = 0.92-0.99). Intraclass correlation coefficients between observers ranged from 0.90 to 0.98. Stent types and configurations determined with CT measurements remained unaltered when reassessed with MR measurements., Conclusion: Measurements obtained with nonenhanced MR angiography appear equally accurate to those of CT angiography in the preoperative planning of abdominal EVAR.

Objectives: The aims of this study were to evaluate the ability of [F]fluorodeoxyglucose (F-FDG)-PET/computed tomography (CT) to identify tumor recurrence, nodal metastases, and distant metastases for surveillance and discuss the optimal timing of F-FDG-PET/CT examination after the completion of treatment for head and neck malignancy., Methods: A total of 319 patients who underwent a post-treatment F-FDG-PET/CT examination for head and neck malignancy were studied. F-FDG-PET/CT findings were compared with the final diagnosis confirmed by histopathological examinations or clinical and radiological follow-up for at least 6 months. Patients were divided into two groups according to the presence or absence of clinical suspicion of recurrent disease. The diagnostic accuracy of F-FDG-PET/CT was analyzed for each group. Patients were also categorized according to the time interval between the completion of treatment and the post-treatment F-FDG-PET/CT examination. Differences in diagnostic accuracy due to the time interval were also evaluated., Results: The diagnostic accuracy of F-FDG-PET/CT was high for both groups. The overall accuracy of F-FDG-PET/CT performed within 2 months (69%) after the completion of treatment was significantly inferior to that performed after 2 months (93%)., Conclusion: F-FDG-PET should be performed immediately for patients with clinically suspected recurrent disease. In others, it should be performed at later than 2 months after the completion of the treatment.

Purpose: To determine if a 20 % reduction in the contrast material dose is acceptable in the CT evaluation of patients with head and neck malignancy., Materials and Methods: Sixty consecutive patients (mean age 67 years) with head and neck malignancy underwent contrast-enhanced CT according to two different protocols: protocol A (80 mL of contrast material administered at an injection rate of 1.5 mL/s) and protocol B (100 mL at 1.9 mL/s). The enhancement of anatomical structures and detectability of metastatic nodes were compared between the two protocols. Pathologic analysis of the surgical resection served as the reference standard., Results: CT numbers of the anatomical structures were not significantly different between the two protocols. Mean sensitivity (64 and 77 % for protocols A and B, respectively), specificity (78 and 84 %), and accuracy (74 and 83 %) tended to be higher for protocol B than for A, but no significant difference was found., Conclusion: Reducing the contrast material dose by 20 % did not significantly impair the enhancement of anatomical structures or the detection of metastatic cervical lymph nodes. Radiologists should therefore consider reducing the contrast material dose used in head and neck CT.

In this article, the authors propose an image registration program of portal images and digitally reconstructed radiography (DRR) images used as simulation images for external beam radiation therapy planning. First, the center of the radiation field in a portal image taken using a computed radiograhy cassette is matched to the center of the portal image. Then scale points projected on a DRR image and the portal image are deleted, and the portal image with the radiation field is extracted. Registration of the DRR and portal images is performed using mutual information as the registration criterion. It was found that the absolute displacement misregistrations in two directions (x, y) were 1.2 +/- 0.7mm and 0.5 +/- 0.3 mm, respectively, and rotation disagreement about the z axis 0.3 +/- 0.3 degrees. It was concluded the proposed method was applicable to image registration of portal and DRR images in radiation therapy.

Purpose: To determine the optimal iodine dose for aortic and hepatic enhancement at MDCT by comparing lean body weight (LBW) with total body weight (TBW)., Materials and Methods: This study was approved by our institutional review committee. One hundred and thirty-six patients were randomized into four groups: 550, 650, 750 mg iodine/(kg of LBW) and 600 mgI/(kg of TBW). The aortic and hepatic contrast enhancements (Δ HUs) during the portal venous-phase and variances of ΔHUs were compared., Results: Mean ΔHUs for 550, 650, 750 mgI/kg LBW and 600 mgI/kg TBW were: 95.1, 109.9, 122.4, and 131.2HU, respectively, for the aorta. For the liver, 43.1, 55.4, 60.8, and 63.5 HU. Mean Δ HUs increased with iodine dose per kg LBW (p<0.01), but no significant difference between 750 mgI/kg LBW and 600 mgI/kg TBW groups. Hepatic enhancement increased by ≥50 HU in 94% of patients with 750 mg/kg LBW. Variance of hepatic enhancement was marginally greater in the 600 mgI/kg TBW than in the 550 and 750 mgI/kg LBW., Conclusion: Hepatic enhancement variation was reduced with iodine doses based on LBW. Iodine dose of 750 mg iodine/kg LBW was appropriate to achieve hepatic enhancement≥50 HU in 94% of patients., (Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.)

Purpose: To prospectively compare 320-detector volumetric and 64-detector helical computed tomographic (CT) images of the pancreas for depiction of anatomic structures, image noise, and radiation exposure., Materials and Methods: This study was approved by the institutional review board, and written informed consent was obtained. A total of 154 patients (85 men, 69 women; age range, 26-85 years; mean age, 67 years) who underwent biphasic (arterial and pancreatic phase) contrast material-enhanced CT performed with a 320-detector scanner were randomized into two groups: the 320-detector group and the 64-detector group. Biphasic transaxial multiplanar reformatted images and volume-rendered CT angiograms were obtained. CT numbers in the abdominal aorta, pancreas, and abdominal wall fat tissue; signal-to-noise ratio (SNR); and dose-length product (DLP) were compared. In addition, image quality and focal lesion depiction (n = 35) were qualitatively determined in the two groups. Unpaired t and Mann-Whitney tests were used for quantitative and qualitative assessment, respectively., Results: No significant difference in CT numbers of the abdominal aorta and pancreas was noted between the two groups. Mean DLP was 43% lower in the 320-detector group (675.4 mGy·cm) than in the 64-detector group (1187.8 mGy·cm) (P < .001). SNR of the abdominal aorta, pancreas, and abdominal wall fat on biphasic images was significantly lower in the 320-detector group than in the 64-detector group (P < .001). Image quality was acceptable in both groups and was slightly better in the 64-detector group for pancreatic phase axial images (P = .02) and arterial phase multiplanar reformatted images (P < .01). No significant difference was found in the depiction of pancreatic parenchyma, main pancreatic duct, focal pancreatic lesions, splanchnic arteries, or most of the small splanchnic arterial branches., Conclusion: A 320-detector CT scan facilitates fast volumetric contrast-enhanced CT of the entire pancreas with acceptable image quality, even though SNR was significantly lower at 320-detector volumetric scanning.

Unlabelled: In FDG-PET for abdominal malignancy, the liver may be assumed as an internal standard for grading abnormal FDG uptake both in early images and in delayed images. However, physiological variables of FDG uptake by the liver, especially the effects of blood glucose level, have not yet been elucidated., Methods: FDG-PET studies of 70 patients examined at 50 to 70 min after injection (60 ± 10 min: early images) and of 68 patients examined at 80 to 100 min after injection (90 ± 10 min: delayed images) were analyzed for liver FDG uptake. Patients having lesions in the liver, spleen and pancreas; patients having bulk tumor in other areas; and patients early after chemotherapy or radiotherapy were excluded; also, patients with blood glucose level over 125 mg/dl were excluded., Results: Mean standardized uptake value (SUV) of the liver, blood glucose level and sex showed no significant differences between early images and delayed images. However, liver SUV in the delayed image showed a larger variation than that in the early image and showed significant correlation to blood glucose level. The partial correlation coefficient between liver SUV and blood glucose level in the delayed image with adjustment for sex and age was 0.73 (P < .0001). Multivariate regression coefficient (95% confidence interval) of blood glucose was 0.017 (0.013-0.021)., Conclusion: Blood glucose level is an important factor affecting the normal liver FDG uptake in nondiabetic patients. In the case of higher glucose level, liver FDG uptake is elevated especially in the delayed image. This may be due to the fact that the liver is the key organ responsible for glucose metabolism through gluconeogenesis and glycogen storage., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Purpose: Multi-slice CT (MSCT) and cone-beam CT (CBCT) are widely used in dental practice. This study compared the spatial resolution of these CT systems to elucidate which CT modalities should be selected for various clinical cases., Materials and Methods: As MSCT and CBCT apparatuses, Somatom Sensation 64 and 3D Accuitomo instruments, respectively, were used. As an objective evaluation of spatial resolution of these CT systems, modulation transfer function (MTF) analysis was performed employing an over-sampling method. The results of MTF analysis were confirmed with a line-pair test using CATPHAN. As a subjective evaluation, a microstructure visualization ability study was performed using a Jcl:SD rat and a head CT phantom., Results: MTF analysis showed that for the in-plane direction, the z-axis ultrahigh resolution mode (zUHR) of the Sensation 64 and 3D Accuitomo instruments had higher spatial resolutions than the conventional mode (64×) of the Sensation 64, but for the longitudinal direction, the 3D Accuitomo had clearly higher spatial resolution than either mode of the Sensation 64. A line-pair test study and microstructure visualization ability studies confirmed the results for MTF analysis. However, images of the rat and the CT phantom revealed that the 3D Accuitomo demonstrated the failure to visualize the soft tissues along with aliasing and beam-hardening artifacts, which were not observed in the Sensation 64., Conclusions: This study successfully applied spatial resolution analysis using MSCT and CBCT systems in a comparative manner. These findings could help in deciding which CT modality should be selected for various clinical cases., (Crown Copyright © 2009. Published by Elsevier Ireland Ltd. All rights reserved.)

Objective: The purpose of this study was to evaluate the effects of noise index and contrast material dose on radiation dose, contrast enhancement, image noise, and image quality in abdominal CT., Subjects and Methods: Contrast-enhanced abdominal CT with tube current modulation was performed on 195 patients. The patients were prospectively randomized into three groups of equal size (protocol A, noise index of 12 HU and 521 mg I/kg; protocol B, 15 HU and 521 mg I/kg; protocol C, 15 HU and 600 mg I/kg). Scanning was initiated 5 and 45 seconds after aortic enhancement reached 100 HU. Attenuation was measured in the aorta, portal vein, and liver. Transverse CT images were qualitatively graded for diagnostic acceptability and image noise. Arterial phase volume-rendered and multiplanar reformatted (MPR) images and portal venous phase MPR CT angiograms were qualitatively graded for depiction of vessels. Contrast enhancement, objective image noise, radiation dose, and qualitative grades were analyzed and compared among the three groups., Results: The contrast enhancement values of the aorta, portal vein, and liver were higher in protocol C than in protocols A and B (p < 0.05). Objective image noise was greater in protocols B and C than in protocol A (p < 0.05). The radiation dose in protocols B and C was 31-32% lower than in protocol A (p < 0.001). Depiction of vessels, diagnostic acceptability, and subjective image noise were comparable in protocols A and C., Conclusion: Use of higher contrast enhancement can compensate for the degradation of image quality resulting from use of a low radiation dose for CT.

Purpose: This study aimed to clarify the size and morphology of the mandible, and to identify the location of the mandibular canal for the planning of the dental implantation., Methods: CT data of 79 Japanese patients (52 male and 27 female) were analyzed., Results: The means of the height and width ranged from 27.6 to 31.0 mm and from 10.5 to 15.8 mm, respectively. The height in male subjects was significantly greater than that in female subjects, and the width in male subjects was slightly but not significantly greater than that in female subjects. The morphology of the mandible was classified into three types. Type C (round) (59-61%) was the most common in the posterior region, followed by type A (lingual concavity) (36-39%), whereas type B (buccal concavity) (58-74%) and type C (17-36%) were the most common types in the anterior region. The distance from the mandibular canal to the alveolar crest, ranged from 15.3 to 17.4 mm. The anterior loop, was observed on 55% of all sides., Conclusions: The size and morphology of the mandible and the location of the mandibular canal were determined clearly using cross-sectional CT images.

Joint photographic experts group(JPEG)and JPEG2000 are widely used as image compression algorithms in medical image database systems. Compressed images have been mainly evaluated by visual assessment on acceptable compression levels in clinical studies. However, to the best of our knowledge, little work has been done to clarify image properties based on physical analysis. In this work, investigations were made to clarify image properties based on physical analysis and to discuss the major causes of degradation related to compression ratios. The physical properties of JPEG2000-compressed and JPEG-compressed images in computed radiography(CR)were compared by measuring the characteristic curve, modulation transfer function(MTF), noise power spectrum(NPS), peak signal-to-noise ratio(PSNR), contrast-to-noise ratio(CNR), and noise equivalent quanta(NEQ). In the MTF measurement, the MTFs of JPEG at high compression ratio showed pronounced degradation at all frequencies. The NPS values of JPEG2000 tend to decrease considerably compared to that of the JPEG at all frequencies with the increase of compression ratio. Furthermore, JPEG2000 images showed higher PSNR, CNR, and NEQ values than JPEG images in the same compression ratio. In these signal-to-noise ratio measurements, good reproducibility of JPEG2000 images was achieved. Overall, JPEG2000 compressed images were far superior to JPEG compressed images. In the physical properties measured, these physical analyses are useful to comprehend physical properties for each irreversible compressed image related to compression ratios in CR.

The aim of this study was to investigate physiological fluorine 18-labeled fluourodeoxyglucose accumulation in the gallbladder (GB) during clinical positron emission tomography (PET) examinations. Three patient groups were included. In Group 1, nine patients with higher fluourodeoxyglucose (FDG) accumulation in the GB than in the liver were examined, followed up and finally diagnosed. In Group 2, the correlations between FDG GB accumulation and various parameters in 286 patients were investigated. In Group 3, changes in FDG GB accumulation between early and delayed PET scans were analyzed in 12 patients. In Group 1, all nine patients who exhibited a high FDG GB accumulation had no evidence of GB disease. In Group 2, FDG GB accumulation was significantly correlated with the injection-scan time interval and inversely correlated with the GB size index. Group 3 showed a significant increase in FDG accumulation in the GB on delayed PET scans, compared with that seen on early scans. In clinical PET studies, FDG accumulation within the GB is infrequently observed but may be due to FDG excretion into the bile. Recognition of this phenomenon may be important to avoid misdiagnosing physiological GB FDG accumulation as indicating a pathologic status and preventing unnecessary examinations.

Objective: This study aimed to provide a classification system for acute pancreatitis by applying the principle that the disease spreads along the retroperitoneal interfascial planes., Materials and Methods: Medical records and computed tomography (CT) images of 58 patients with acute pancreatitis treated between 2000 and 2005 were reviewed. The retroperitoneum was subdivided into 10 components according to the concept of interfascial planes. Severity of acute pancreatitis was graded according to retroperitoneal extension into these components. Clinical courses and outcomes were compared with the grades. The prognostic value of our classification system was compared with that of Balthazar's CT severity index (CTSI)., Results: Retroperitoneal extension of acute fluid collection was classified into five grades: Grade I, fluid confined to the anterior pararenal space or retromesenteric plane (8 patients); Grade II, fluid spreading into the lateroconal or retrorenal plane (16 patients); Grade III, fluid spreading into the combined interfascial plane (8 patients); Grade IV, fluid spreading into the subfascial plane beyond the interfascial planes (15 patients); and Grade V, fluid intruding into the posterior pararenal space (11 patients). Morbidity and mortality were 92.3% and 38.5% in the 26 patients with Grade IV or V disease, and 21.9% and 0% in the 32 patients with Grade I, II, or III disease. Morbidity and mortality were 86.7% and 33.3% in patients with disease classified "severe" according to the CTSI, and 37.5% and 9.4% in patients with disease classified "mild" or "moderate"., Conclusion: Classification of acute pancreatitis based on CT-determined retroperitoneal extension is a useful indicator of the disease severity and prognosis without the need for contrast-medium enhanced CT.

The aim of this study was to investigate the correlations between (18)F-FDG uptake by bone marrow and various hematological parameters. Forty-eight patients who underwent FDG-PET/CT studies and also received hematological examinations within 5 days before or after the PET study were included in this study. All patients had not received chemotherapy. FDG uptake by bone marrow was measured as a standardized uptake value (SUV) on three-dimensional PET/CT fusion images, and the uptake ratio (UR) of the SUV of bone marrow to the SUV of longitudinal dorsal muscle was calculated. The correlations between the SUV and the UR of bone marrow and various hematological parameters were evaluated. Bone marrow FDG uptake was strongly correlated with the white blood cell counts but was not significantly correlated with the red blood cell and platelet counts. The neutrophil count was significantly correlated with bone marrow FDG uptake but the lymphocyte count was not. FDG uptake by bone marrow was specifically correlated with the neutrophil count, suggesting that the FDG uptake by bone marrow reflects marrow metabolism that is mainly regulated by granulocyte progenitors and stimulated by endogenous hematopoietic growth factors. They may also be helpful in interpreting PET images, especially for diagnosing bone marrow involvement by malignancy.