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Purpose Teleradiology has been widely used nationwide in various ways. In order to prepare a guideline, it was recognized that a survey on the actual condition of teleradiology in Korea was necessary. Materials and Methods The questionnaires were administered to training hospitals. Interviews were also conducted with teleradiology centers and teleradiologists. The bid records of Government e-Procurement System (Narajangteo) was examined. Results The main reason for requesting teleradiology was manpower shortage. The contracts were made on a per-case basis and all were interpreted with the reading radiolgists’ names on the report. The report seemed to be delivered timely and access to clinical information was possible in some cases. The teleradiology fees collected from the e-procurement system were lower than those from other subjects, which is thought to be the result of the lowest bid method. Conclusion Guidelines for teleradiology should be developed on legitimate interpretations. In addition, continuous efforts to solve the problem of quality deterioration of teleradiology will be needed.

Physical abuse is a significant cause of morbidity and mortality in the pediatric population. Young children, particularly in the first year of life, are most vulnerable to physical abuse. To evaluate suspected physical abuse, radiologists play a vital role by detecting radiological findings suggestive of physical abuse and differentiating them from other pathologies. This review focuses on radiologic findings, including those for fractures, abusive head trauma, spinal injury, and thoracoabdominal injury, commonly discovered in physically abused children, with special emphasis on biomechanical forces that produce injuries.

Emerging concerns regarding the hazard from medical radiation including CT examinations has been suggested. The purpose of this study was to observe the longitudinal changes of CT radiation doses of various CT protocols and to estimate the long-term efforts of supervising radiologists to reduce medical radiation. Radiation dose data from 11 representative CT protocols were collected from 12 hospitals. Attending radiologists had collected CT radiation dose data in two time points, 2007 and 2010. They collected the volume CT dose index (CTDIvol) of each phase, number of phases, dose length product (DLP) of each phase, and types of scanned CT machines. From the collected data, total DLP and effective dose (ED) were calculated. CTDIvol, total DLP, and ED of 2007 and 2010 were compared according to CT protocols, CT machine type, and hospital. During the three years, CTDIvol had significantly decreased, except for dynamic CT of the liver. Total DLP and ED were significantly decreased in all 11 protocols. The decrement was more evident in newer CT scanners. However, there was substantial variability of changes of ED during the three years according to hospitals. Although there was variability according to protocols, machines, and hospital, CT radiation doses were decreased during the 3 years. This study showed the effects of decreased CT radiation dose by efforts of radiologists and medical society., Graphical Abstract

This paper presents the results of experimental investigations on the shear failure behaviors of reinforced concrete beams using ductile fiber reinforced cementitious composite (DFRCC). Total 10 RC beams of 150x300x1,000mm size were tested by 4-point bending under the displacement control. The main parameters of the experiment are surface treatment by grinding and preloading to the cracking point in the repair process. The load-displacement curves, diagonal tension cracking load, flexural cracking load, and shear strength were obtained. The test results showed that the DFRCC can be used effectively for restoring the shear strength approximately 99% to the original value under the condition that the appropriate thickness and surface treatment like grinding are assured. For further research, the specimens taken from real deteriorated structures will need to be tested after being repaired with DFRCC.

Aim To investigate the correlation between implant appearance on ultrasound (US) and voiding cystourethrography (VCUG) results after dextranomer–hyaluronic acid copolymer (DxHA) injection in children with vesicoureteral reflux (VUR). Materials and methods Consecutive cases of primary VUR treated by endoscopic subureteral injection of DxHA were retrospectively reviewed. All children had postoperative bladder US and VCUG with a mean interval of 34 days and 47 days after injection, respectively. VUR resolution at postoperative VCUG was considered as treatment success. Implant appearance on US was graded according to the retained volume and its location by visual inspection; it was then correlated with VCUG results using the Spearman correlation coefficient. Results A total of 36 children (56 ureters) were identified in which 38 ureters (68%) had a clearly visualized implant on postoperative US and 40 ureters (71%) showed VUR resolution. The sensitivity of implant visualization on US for predicting reflux resolution was 73% (29/40), specificity 44% (7/16), positive predictive value 76% (29/38), and negative predictive value 39% (7/18). The grade 1, grade 2, and grade 3 implant appearances showed VUR resolution in 88% (22/25), 54% (7/13), and 61% (11/18), and showed persistent VUR in 8% (2/25), 15% (2/13), and 28% (5/18), respectively (p = 0.032). Conclusion The implant appearance on postoperative US showed good correlation with VCUG results in the early post-injection period. Large retained implants were associated with treatment success, while small or non-visualized implants were related to the persistent reflux.

Metabolic disorders of the brain that manifest in the neonatal or early infantile period are usually associated with acute and severe illness and are thus referred to as devastating metabolic disorders. Most of these disorders may be classified as organic acid disorders, amino acid metabolism disorders, primary lactic acidosis, or fatty acid oxidation disorders. Each disorder has distinctive clinical, biochemical, and radiologic features. Early diagnosis is important both for prompt treatment to prevent death or serious sequelae and for genetic counseling. However, diagnosis is often challenging because many findings overlap and may mimic those of more common neonatal conditions, such as hypoxic-ischemic encephalopathy and infection. Ultrasonography (US) may be an initial screening method for the neonatal brain, and magnetic resonance (MR) imaging is the modality of choice for evaluating metabolic brain disorders. Although nonspecific imaging findings are common in early-onset metabolic disorders, characteristic patterns of brain involvement have been described for several disorders. In addition, diffusion-weighted images may be used to characterize edema during an acute episode of encephalopathy, and MR spectroscopy depicts changes in metabolites that may help diagnose metabolic disorders and assess response to treatment. Imaging findings, including those of advanced MR imaging techniques, must be closely reviewed. If one of these rare disorders is suspected, the appropriate biochemical test or analysis of the specific gene should be performed to confirm the diagnosis.

This paper presents the results of flexural test of concrete beams reinforced with GFRP and conventional steel reinforcement for comparison. The beams were tested under a static load to examine the effects of the reinforcement ratio and compressive strength of concrete on cracking, deflection, ultimate capacity, and modes of failure. The test results showed that the ultimate capacity of the GFRP-reinforced beams increased with increasing reinforcement ratio and concrete strength, showing a 41.3~51.6% increase compared to steel reinforced beams. The deflections at maximum loads of the GFRP reinforced beams were 4.1~6.3 times higher that of steel reinforced beams. The measured deflections of GFRP reinforced beams decreased approximately 31% compared to the theoretical predictions because the theoretical flexural stiffness was underestimated at the maximum loads. For the GFRP-reinforced beams, the ACI code 440 design method resulted in conservative flexural strength estimates.

The purpose of this article is to review the clinical and imaging features of focal nodular hyperplasia (FNH) developed in children.At a single institution, pediatric patients who underwent imaging studies and who had pathologically proven FNH were studied. Clinical characteristics, including presenting symptoms and signs and the presence of underlying disease, were reviewed from the medical records. Imaging features of FNHs, including the number, size, ultrasound echogenicity and vascularity, CT attenuation, MRI signal intensity and enhancement pattern, and the presence of a central scar, were evaluated.Twenty-five patients (11 boys and 14 girls; median age, 8.6 years) were found to have a solitary (n = 23) or multiple (n = 2) FNH lesions with a mean size of 4.9 cm (range, 1-10 cm). Multiple lesions were associated with small size of the lesions and history of malignancy treated by chemotherapy. Most patients were asymptomatic (n = 22). Biliary atresia was the most common underlying disease (n = 5). On ultrasound, FNHs most commonly appeared to be isoechoic and hypervascular. On dynamic CT and MRI, strong enhancement on the arterial phase and becoming isoattenuated or of isointense signal intensity on the portal or delayed phase was common. A central scar was usually noted in large lesions in about half the cases.Pediatric FNH is uncommon and usually is found incidentally in otherwise healthy children. However, it may occur in children who have underlying diseases, including biliary atresia. In addition, it can be encountered during surveillance of childhood cancer survivors with less common imaging features, including lack of a central scar and multiplicity.

To establish the risks of developing of hepatic tumours and to investigate their clinical and imaging findings in children with biliary atresia (BA) after Kasai portoenterostomy (Kasai).Among 157 children who had undergone Kasai for BA over an 18 year period, patients who had newly developed hepatic tumours were identified. Patient demographics, clinical features, and imaging findings were retrospectively reviewed.Three male and 10 female patients (mean age 3.9 years) all (8%, of 157) had single hepatic tumours, which were confirmed in 10 explanted and three non-explanted livers. Ten (77%) were benign and three (23%) were malignant. Of the benign hepatic tumours, focal nodular hyperplasia (FNH; n = 6) was the most common, followed by regenerative nodules (n = 3) and adenoma (n = 1). All FNH appeared in young children1 year of age and showed a subcapsular location, bulging contour, and lack of central scar. Malignant tumours included two hepatocellular carcinomas and one cholangiocarcinoma.Hepatic tumours developed in approximately 8% of children with BA after Kasai. Although benign tumours, including FNHs and regenerative nodules, were more common than malignant tumours, screening with alpha-foetoprotein (AFP) levels and regular imaging studies are the mainstay of malignant tumour detection.

Purpose To evaluate the differences in opinion among radiologists working in different types of medical institutions in Korea, through questionnaires. Materials and Methods Korean board-certified radiologists who participated in the survey in 2017. Results Of the 316 radiologists who responded to the survey, 46.1, 20.3, 16.3, and 10.1% were working in university hospitals, general hospitals, hospitals, and clinics, respectively. More than half the radiologists (52.1%) considered teleradiology necessary, and the most-cited reason was a flexible work style. On the contrary, poor quality of radiology reports was the most-cited reason for considering teleradiology unnecessary. Although regulations for image quality, work environment, and radiology reports were considered necessary, the smaller the size of medical institution, the lower was the agreement rate. Among all responders, most radiologists thought that teleradiology would reduce the scope of radiology. However, most radiologists working in clinics thought that teleradiology would expand the field of radiology. Most responders (94.2%) required teleradiology guidelines provided by the Korean Society of Radiology. Conclusion The results of this survey showed radiologists’ perspective on various aspects of teleradiology. There were significant differences in opinion among radiologists working in different types of medical institutions.

The purpose of this study is to investigate the dynamic MRI findings and clinical features of benign hypervascular hepatic nodules in childhood-cancer survivors.We reviewed dynamic MRI findings and clinical features in 15 patients who had been treated for childhood malignant solid tumors and in whom hypervascular hepatic nodules were later found on surveillance imaging by either CT or ultrasound (or both). The benign nature of the lesion was based on histologic examination or clinical and radiologic follow-up (or both).Time between initial diagnosis of malignancy and detection of the hepatic nodule ranged from 4.5 to 13.5 years with the majority of the malignancies being neuroblastoma treated by high-dose chemotherapy and hematopoietic stem cell transplantation. A total of 43 nodules were detected, often multiple and small. Most of the lesions were isointense or slightly hyperintense on T2-weighted imaging and isointense or slightly hypointense on T1-weighted imaging. All nodules had intense enhancement on the arterial phase and were isointense or slightly hyperintense on the delayed phase. A central scar was seen in four. Additionally, hepatic hemosiderosis was noted in four patients, in whom all the lesions were hyperintense on both T1- and T2-weighted imaging.Benign hypervascular hepatic nodules in survivors of childhood malignancy occur years after high-dose chemotherapy and hematopoietic stem cell transplantation. Dynamic MRI findings including intense arterial enhancement and absence of washout in the delayed phase are of great value in the differential diagnosis of these hepatic nodules.

To investigate the ultrasound findings associated with early liver transplantation (LT) after Kasai portoenterostomy (Kasai) in children with biliary atresia (BA).Children with BA (n = 30) who underwent Kasai were classified into early LT group (n = 17, LT within 1 year after Kasai) and Kasai alone group (n = 13, alive with their native livers). Serial ultrasound (baseline and follow-up before LT or post-Kasai 1 year) images were reviewed to investigate significant ultrasound findings related to early LT using both univariate and multivariate models. Images were reviewed focusing on the hepatic artery diameter, portal vein diameter, and signs of portal hypertension.The hepatic artery diameters in the early LT group were significantly larger than those in the Kasai alone group both at baseline (p = 0.007) and follow-up ultrasound (p0.001). The portal vein diameters on follow-up ultrasound were smaller in the early LT group than the Kasai alone group (p0.001). On multivariate analysis, baseline hepatic artery diameter (hazard ratio, 20.4; 95% confidence interval, 3.7-110.6; p0.001) and the presence of splenomegaly at follow-up ultrasound (17.7; 2.6-121.8; p = 0.004) were significant predictors associated with early LT. The optimal cut-off value of the baseline hepatic artery diameter was 1.9 mm (82% sensitivity and 77% specificity).Enlarged hepatic artery at baseline ultrasound and the presence of splenomegaly at follow-up ultrasound were associated with early LT after Kasai in children with BA.

Purpose To evaluate the accuracy of pre-operative MRI for the detection of optic nerve invasion in retinoblastoma. Materials and methods Institutional review board approval and informed consent were waived for this retrospective study. A total of 41 patients were included. Inclusion criteria were histologically proven retinoblastoma, availability of diagnostic-quality preoperative MR images acquired during the 4 weeks before surgery, unilateral retinoblastoma, and normal-sized optic nerve. Two radiologists retrospectively reviewed the MR images independently. Five imaging findings (diffuse mild optic nerve enhancement, focal strong optic nerve enhancement, optic sheath enhancement, tumor location, and tumor size) were evaluated against optic nerve invasion of retinoblastoma. The predictive performance of all MR imaging findings for optic nerve invasion was also evaluated by the receiver operating characteristic curve analysis. Results Optic nerve invasion was histopathologically confirmed in 24% of study population (10/41). The differences in diffuse mild enhancement, focal strong enhancement, optic sheath enhancement, and tumor location between patients with optic nerve invasion and patients without optic nerve invasion were not significant. Tumor sizes were 16.1 mm (SD: 2.2 mm) and 14.9 mm (SD: 3.6 mm) in patients with and without optic nerve involvement, respectively (P = 0.444). P-Values from binary logistic regression indicated that all five imaging findings were not significant predictors of tumor invasion of optic nerve. The AUC values of all MR imaging findings for the prediction of optic nerve invasion were 0.689 (95% confidence interval: 0.499–0.879) and 0.653 (95% confidence interval: 0.445–0.861) for observer 1 and observer 2, respectively. Conclusion Findings of MRI in patients with normal-sized optic nerves have limited usefulness in preoperatively predicting the presence of optic nerve invasion in retinoblastoma.

Clinical evidence supporting triple rule-out computed tomography (TRO-CT) for rapid screening of cardiovascular disease is limited. We investigated the clinical value of TRO-CT in patients with acute chest pain.We retrospectively enrolled 1024 patients who visited the emergency department (ED) with acute chest pain and underwent TRO-CT using a 128-slice CT system. TRO-CT was classified as "positive" if it revealed clinically significant cardiovascular disease including obstructive coronary artery disease, pulmonary thromboembolism, or acute aortic syndrome. The clinical endpoint was occurrence of a major adverse cardiovascular event (MACE) within 30 days, defined by a composite of all cause death, myocardial infarction, revascularization, major cardiovascular surgery, or thrombolytic therapy. Clinical risk scores for acute chest pain including TIMI, GRACE, Diamond-Forrester, and HEART were determined and compared to the TRO-CT findings.TRO-CT revealed clinically significant cardiovascular disease in 239 patients (23.3%). MACE occurred in 119 patients (49.8%) with positive TRO-CT and in 7 patients (0.9%) with negative TRO-CT (p 0.001). Sensitivity, specificity, positive predictive value, and negative predictive value of TRO-CT was 95%, 88%, 54%, and 99%, respectively. TRO-CT was a better discriminator between patients with vs. without events as compared to clinical risk scores (c-statistics = 0.91 versus 0.64 to 0.71; integrated discrimination improvement = 0.31 to 0.37; p 0.001 for all comparisons). Patients with a negative TRO-CT showed shorter ED stay times and admission rates compared to patients with positive TRO-CT, irrespective of clinical risk scores (p 0.001 for all comparisons).Triple rule-out CT has high predictive performance for 30-day MACE and permits rapid triage and low admission rates irrespective of clinical risk scores.

Background Invasive aspergillosis (IA) is a major cause of morbidity and mortality in immunocompromised children. We investigated the usefulness of an Aspergillus galactomannan (GM) antigen assay as a diagnostic tool for IA in pediatric cancer patients and hematopoietic cell transplantation (HCT) recipients. Procedure The GM antigen assay results were analyzed in 749 blood samples from 99 patients. A GM index (GMI) greater than or equal to 0.5 on at least two separate occasions was considered positive. A review of the clinical data was performed for subjects with proven or probable IA. Results Twenty-one of 23 patients with proven or probable IA had positive GM antigen test results (91.3% sensitivity, 95% CI 71.9–98.9; 81.7% specificity, 95% CI 69.6–90.5; P

To compare the neurodevelopmental outcomes between preterm infants with diffuse excessive high signal intensity (DEHSI) and those without DEHSI on magnetic resonance (MR) images, in association with other white matter lesions.This retrospective study was approved by the institutional review board, and requirement to obtain informed consent was waived. High-risk preterm infants (n = 126) who underwent screening brain MR imaging at near-term-equivalent age were classified into two groups according to the presence of DEHSI. Bayley Scales of Infant Development-II, presence of cerebral palsy, and neurosensory impairment between 18 and 24 months of age were compared between the two groups. The associations of MR findings of other white matter lesions (cystic encephalomalacia, punctate lesions, loss of volume, ventricular dilatation, and delayed myelination) and subsequent outcomes were also analyzed. Outcome data were evaluated by using exact logistic regression analyses and Fisher exact test.DEHSI was present in 75% (95 of 126) of infants. Subsequent neurodevelopmental outcomes did not differ significantly between the two groups. Severe motor delay and cerebral palsy were more common in infants with both DEHSI and other white matter lesions as compared with infants with normal white matter (P = .001 and P.001, respectively). Among other white matter lesions, cystic encephalomalacia (odds ratio, 19.6; 95% confidence interval: 1.3, 333.3) and punctate lesions (odds ratio, 90.9; 95% confidence interval: 6.4, 1000) were significant predictors of cerebral palsy.Although the incidence of DEHSI was high (75%) in preterm infants at near-term-equivalent age MR imaging, DEHSI was not predictive of following adverse outcomes. Cystic encephalomalacia and punctate lesions were more significant predictors of cerebral palsy.

Pilomyxoid astrocytoma (PMA) is a recently described astrocytic tumor that has been previously diagnosed as pilocytic astrocytoma (PA). The purpose of this study was to describe the imaging features of PMAs in comparison with PAs.We retrospectively reviewed CT/MR images and medical records of 10 patients with PMA and 38 patients with PA. The mean ages of patients with PMA and PA were 10 and 15 years, respectively. Imaging features including location, composition, enhancement pattern, presence of calcification, hemorrhage, and leptomeningeal dissemination were compared in patients with two tumor types.Six PMAs (60%) occurred at the suprasellar area and the cerebellum was the most common (45%) site of PA. Solid component was dominant in eight PMAs (80%) and in 19 PAs (50%). All of the PMAs containing solid mass (n=8) included non-enhancing portion while 12/37 (32%) PAs included non-enhancing solid portion (p0.05). Leptomeningeal dissemination was noted in five PMAs (50%) and one PA (3%) (p0.05). Other imaging findings were not significantly different.A younger age, more frequent occurrence at the suprasellar area, mainly solid mass containing non-enhancing portion, and more frequent leptomeningeal dissemination are helpful differential features of PMAs as compared to PAs.

Objective: To evaluate the radiological and clinical fi ndings of congenital cystic neuroblastomas as compared with those of the cystic presentation of neonatal adrenal hemorrhage. Materials and Methods: We analyzed the US (n = 52), CT (n = 24), and MR (n = 4) images as well as the medical records of 28 patients harboring congenital cystic neuroblastomas (n = 16) and neonatal adrenal hemorrhagic pseudocysts (n = 14). The history of prenatal detection, location, size, presence of outer wall enhancement, internal septations, solid portion, calcifi cation, turbidity, vascular fl ow on a Doppler examination, and evolution patterns were compared in two groups of cystic lesions, by Fischer’s exact test. Results: All (100%) neuroblastomas and three (21%) of the 14 hemorrhagic pseudocysts were detected prenatally. Both groups of cystic lesions occurred more frequently on the right side; 11 of 16 (69%) for neuroblastomas and 11 of 14 (79%) for hemorrhagic pseudocysts. The size, presence of solid portion, septum, enhancement, and turbidity did not differ signifi cantly (p > 0.05) between the two groups of cystic lesions. However, tiny calcifi cations (n = 3) and vascular fl ow on color Doppler US (n = 3) were noted in only neuroblastomas. The cystic neuroblastomas became complex solid and cystic masses, and did not disappear for up to 90 days in the three following cases, whereas 11 of the 14 (79%) hemorrhagic pseudocysts disappeared completely and the three remaining (27%) evolved to calcifi cations only. Conclusion: Although the imaging fi ndings of two groups of cystic lesions were similar, prenatal detection, the presence of calcifi cation on initial images, vascularity on color Doppler US, and evolution to a more complex mass may all favor neuroblastomas.

Objective To investigate the serial CT findings of Paragonimus westermani infected dogs and the microscopic structures of the worm cysts using Micro-CT. Materials and methods This study was approved by the committee on animal research at our institution. Fifteen dogs infected with P. westermani underwent serial contrast-enhanced CT scans at pre-infection, after 10 days of infection, and monthly thereafter until six months for determining the radiologic-pathologic correlation. Three dogs (one dog each time) were sacrificed at 1, 3 and 6 months, respectively. After fixation of the lungs, both multi-detector CT and Micro-CT were performed for examining the worm cysts. Results The initial findings were pleural effusion and/or subpleural ground-glass opacities or linear opacities at day 10. At day 30, subpleural and peribronchial nodules appeared with hydropneumothorax and abdominal or chest wall air bubbles. Cavitary change and bronchial dilatation began to be seen on CT scan at day 30 and this was mostly seen together with mediastinal lymphadenopathy at day 60. Thereafter, subpleural ground-glass opacities and nodules with or without cavitary changes were persistently observed until day 180. After cavitary change of the nodules, the migratory features of the subpleural or peribronchial nodules were seen on all the serial CT scans. Micro-CT showed that the cyst wall contained dilated interconnected tubular structures, which had communications with the cavity and the adjacent distal bronchus. Conclusion The CT findings of paragonimiasis depend on the migratory stage of the worms. The worm cyst can have numerous interconnected tubular channels within its own wall and these channels have connections with the cavity and the adjacent distal bronchus.

Hepatocellular carcinoma (HCC) is a rare pediatric malignancy that is usually advanced at diagnosis, with a relatively poor prognosis. Extensive treatment, including complete tumor resection, is believed to be necessary for cure. This study was performed to analyze treatment results and to search for prognostic factors of pediatric HCC.Between March 1982 and February 2004 a total of 16 children had been diagnosed as having HCC in our institution, and a retrospective analysis was performed.The median age at diagnosis was 10.5 years, and the male/female ratio was 11:5. As a predisposing condition, hepatitis B virus (HBV) infections were present in 11 (68.8%) and liver cirrhosis in 8 (50.0%). Including 1 patient with a liver transplant, 4 patients (25.0%) underwent a primary operation with complete tumor resection, and 11 (68.8%) received neoadjuvant chemotherapy because of their inoperable state at diagnosis. After neoadjuvant chemotherapy, complete tumor resection was performed in four (36.4%). Thus complete resection was undertaken in a total of eight patients (50.0%). The estimated 5-year survival rate of all patients was 27.3%. The 5-year survival rate for patients who underwent complete tumor resection was 62.5%, and for those who underwent palliative resection or no operation it was 0%. The statistically significant prognostic factors were tumor stage, presence of metastasis, and complete tumor resection.This study confirmed that complete tumor resection is essential for cure in pediatric patients with HCC, and neoadjuvant chemotherapy improves the tumors' resectability.

With respect to the researches of the optical flying head(OFH) , the head-gimbal assembly should be analyzed to guarantee the stable fabrication and the characteristics of shock resistance. The suitable design is proved through the Probabilistic analysis of the design parameters and material properties of the model. Probabilistic analysis is a technique that be used to assess the effect of uncertain input parameters and assumptions on your analysis model. Using a probabilistic analysis you can find out how much the results of a finite elements analysis are affected by uncertainties in the model. Another factor is analysis of the dynamic shock analysis. For the mobile application, one of the important requirements is durability under severe environmental condition, especially, resistance to mechanical shock. An important challenge in the disk recording is to improve disk drive robustness in shock environments. If the system comes in contact with outer shock disturbance. the system gets critical damage in head-gimbal assembly or disk. This paper describes probabilistic and dynamic shock analysis of head-gimbal assembly in micro MO drives using OFH slider.

To reach high areal density, less track pitch is expected and more servo bandwidth is required. One approach to overcoming the problem is by using dual stage servo system. For this system. we have suggested new milliactuator based on the shear mode of piezoelectric elements to drive the head suspension assembly. In this paper, we introduce milliactuator and controller design method, PQ method. PQ method reduces the controller design problem for DISO (dual-input/single-output) systems to two standard controller design problems for SISO ( single-input/single-output) problems. The first part of PQ method directly addresses the issue of actuator output contribution, and the second part allows the use of traditional loop shaping to achieve the overall system performance. This paper shows how to employ the PQ method to meet aggressive close-loop performance specifications for a disk drive system with a VCM and piezoelectric milliactuator.

Periosteal new bone formation is seen after the irritation of periosteum. Typical finding of Caffey’s disease is the extensive new bone of mandible. In rapid growing disease such as malignancy and osteomyelitis, there is Codman’s triangle. In benign disease including fracture and even normal growth, single layer of periosteal new bone is formed.

Meningioangiomatosis (MA) is a rare benign cerebral lesion. We aimed to evaluate the CT and MR features of sporadic MA, with a focus on the correlation between imaging and histopathologic findings.CT (n = 7) and MR (n = 8) images of eight patients (6 men and 2 women; mean age, 12.8 years; range, 4-22 years) with pathologically proven MA were retrospectively reviewed. After dividing the MA lesions according to their distribution into cortical and subcortical white matter components, the morphologic characteristics were analyzed and correlated with histopathologic findings in seven patients.CT and MR images showed cortical (n = 4, 50%) and subcortical white matter (n = 7, 88%) components of MA. All four cortical components revealed hyperattenuation on CT scan and T1 isointensity/T2 hypointensity on MR images, whereas subcortical white matter components showed hypoattenuation on CT scan and T1 hypointensity/T2 hyperintensity on MR images. Two cortical components (25%) demonstrated enhancement and one subcortical white matter component demonstrated cystic change. Seven cases were available for imaging-histopathologic correlation. In all seven cases, the cortex was involved by MA and six patients (86%) showed subcortical white matter involvement by MA. There were excellent correlations between the imaging and histopathologic findings in subcortical white matter components, and the accuracy was 100% (seven of seven); whereas there were poor correlations in cortical components, and the accuracy was 43% (three of seven).The cerebral cortex and subcortical white matter were concomitantly involved by MA. Subcortical white matter components of MA were more apparent than cortical components on CT and MR imaging.

Currarino syndrome (CS) is characterized by the triad of partial sacral defect, anorectal malformation, and presacral mass and has been recently reported to be associated with mutations in the HLXB9 gene, which have been suggested to be the genetic background of CS. Phenotypic expression of the HLXB9 gene mutation in a CS family varies from an incomplete to a complete triad. We present variable clinical and imaging features of CS in three siblings with genetically identified HLXB9 mutation. Clinical presentation, management and outcome were also reviewed, and we suggest that magnetic resonance imaging should be used as a screening tool in the members of a CS family with genetic mutation in order to avoid morbidity and mortality from an undiagnosed presacral mass.

Aim The aim was to review the clinical and imaging features of hypervascular hepatic nodule (HHN) in childhood cancer survivors. Materials and methods We retrospectively reviewed 11 pediatric patients (female:male, 7:4; age range, 4.0–12.3 years) who had HHNs detected by surveillance computed tomography (CT) after treatment of a malignant solid tumor and subsequently followed by serial imaging without evidence of recurrent malignancy. The lesions were analyzed in terms of number, size, location, CT and ultrasonographic (US) features, and changes in background liver. In addition, clinical features were investigated along with follow-up changes of HHNs by imaging monitoring. Results Time between initial diagnosis of malignancy and HHN occurrence ranged from 3.2 to 8.5 years (median, 5.8 years). Ten patients had received high-dose chemotherapy and autologous stem cell transplantation for advanced neuroblastoma. A total of 22 nodules were detected, being multiple in six patients and measuring 0.5–3.0 cm in size. At sequential postcontrast CT, nodules demonstrated moderate to strong enhancement during the earlier phase and were isoattenuated during the later phase. On US, they appeared as hypo- or isoechoic lesions. During follow-up, 11 nodules (50%) regressed, 6 (27%) progressed, and 5 (23%) remained stable. Additional HHNs were noted in four patients during follow-up. Conclusion Childhood cancer survivors are at risk of developing HHNs, which are often multiple and small, years after completing chemotherapy. They are nonaggressive and tend to have a benign course, making conservative management reasonable.

The purpose of this study was to analyze the MDCT and MRI findings in patients with unroofed coronary sinus syndrome.This retrospective study included 11 patients with unroofed coronary sinus syndrome (10 adults, one child) without persistent left superior vena cava and one adult with communication of the left atrium and coronary sinus via an anomalous vein (unroofed coronary sinus variant). Four patients underwent contrast-enhanced ECG-gated MDCT; six, MRI; and two patients, both CT and MRI. We also measured the coronary sinus on the CT scans of 28 adults with normal cardiac anatomy and 10 adults with persistent left superior vena cava and compared the measurements with those in the patients with unroofed coronary sinus syndrome. Seven patients underwent surgical treatment of unroofed coronary sinus syndrome.At echocardiography, unroofed coronary sinus syndrome was not clearly discriminated from atrial septal defect in two patients and was not suspected in three patients. CT and MRI showed that 11 patients had a defect in which the coronary sinus communicated with the left atrium and that the other patient had atresia of the coronary sinus orifice with an anomalous vein connecting the coronary sinus and left atrium. In patients with unroofed coronary sinus syndrome, the mean standardized diameter of the coronary sinus according to the patient's body surface area was 15 ± 4 mm/m², similar to that of the control group with persistent left superior vena cava (15 ± 6 mm/m²; p = 0.97) and significantly greater than that of the group with normal cardiac anatomy (7 ± 2 mm/m²; p0.0001).CT and MRI facilitate definite diagnosis of unroofed coronary sinus syndrome.

To compare the clinical and imaging features of posttransplantation lymphoproliferative disorder (PTLD) in pediatric patients who underwent hematopoietic cell transplantation with those in pediatric patients who underwent liver transplantation.This study was approved by the institutional review board, and the requirement to obtain informed consent was waived. The authors retrospectively reviewed the medical records and images of 552 hematopoietic cell transplant recipients and 195 liver transplant recipients. PTLD was histopathologically confirmed in 17 of the patients who underwent hematopoietic cell transplantation and 27 of the patients who underwent liver transplantation. The overall frequency, clinical course, histopathologic type, and imaging findings of PTLD were compared between the two patient groups by using the Fisher exact test.The overall frequency of PTLD was 3% (17 of 552 patients) after hematopoietic cell transplantation (12% [nine of 75 patients] after umbilical cord blood transplantation) and 14% (27 of 194 patients) after liver transplantation. PTLD occurred within 6 months of transplantation in 14 of the 17 hematopoietic cell recipients (82%) and 11 of the 27 liver recipients (41%) (P = .012). Histopathologic examination revealed monomorphic disease in 11 of the 17 hematopoietic cell recipients (65%) and eight of the 27 liver recipients (30%) (P = .031). The abdomen was the most common site of involvement in both groups. Extraabdominal PTLD developed in 12 of the 17 hematopoietic cell recipients (71%) and five of the 27 liver recipients (19%) (P = .002). Although 15 of the 17 patients with hematopoietic cell transplantation-related PTLD (88%) exhibited responses after treatment, the overall mortality rate was 35% (six of 17 patients). All 27 patients with PTLD after liver transplantation improved after treatment and remain alive.PTLD after umbilical cord blood transplantation occurred as frequently as liver transplantation-related PTLD. Compared with liver transplantation-related PTLD, PTLD after hematopoietic cell transplantation is characterized by an earlier onset, a higher proportion of malignant monomorphic disease, and a worse outcome.

Aim To describe the frequency, pattern, and outcome of chest radiographic abnormalities in children with H1N1 influenza infection. Materials and methods Three hundred and fourteen paediatric patients with confirmed H1N1 influenza infection who underwent chest radiography at presentation at a single institution during the outbreak in 2009 were retrospectively reviewed. Abnormal chest radiographic findings related to acute infection were analysed in terms of frequency, pattern, and distribution. Medical records and follow-up radiographs were also reviewed to assess clinical features and outcomes. Results Chest lesions suggesting acute infection were identified in 49 (16%) patients (mean age 8.2 years, range approximately 1.8–18.5 years). The most common finding was prominent peribronchial marking (71%), followed by air-space opacity (51%) with or without volume decrease, generalized hyperinflation (24%), and pleural effusion (20%). Other minor findings included pneumomediastinum (n = 2) and a nodule (n = 1). Distributions were bilateral (55%) or unilateral (45%) with frequent involvement of lower (78%), and middle (59%) lung zones. Thirty-nine patients (80%) were hospitalized and six (12%) required mechanical ventilation, followed by recovery. Thirty-one out of the 33 patients that underwent follow-up radiography showed marked resolution of all radiographic abnormalities. Conclusion The frequency of a chest radiographic abnormality was found to be low in children with H1N1 influenza infection. Although typical radiographic findings of a viral lower respiratory infection were more common, unilateral involvement and air-space opacity were common, often with pleural effusion. Furthermore, pulmonary lesions showed near complete resolution on follow-up radiographs in the majority of patients.

OBJECTIVE We wanted to compare the efficiency of multipolar radiofrequency ablation (RFA) using three perfused-cooled electrodes with multiple overlapping and simultaneous monopolar techniques for creating an ablation zone in ex vivo bovine livers and in in vivo porcine livers. MATERIALS AND METHODS In the ex vivo experiments, we used a 200 W generator (Valleylab, CC-3 model) and three perfused-cooled electrodes or internally cooled electrodes to create 30 coagulation zones by performing consecutive monopolar RFA (group A, n = 10), simultaneous monopolar RFA (group B, n = 10) or multipolar RFA (group C, n = 10) in explanted bovine livers. In the consecutive mode, three ablation spheres were created by sequentially applying 150 watts radiofrequency (RF) energy to the internally cooled electrodes for 12 minutes each for a total of 36 minutes. In the simultaneous monopolar and multipolar modes, RF energy was concurrently applied to the three perfused-cooled electrodes for 20 minutes at 150 watt with instillation of 6% hypertonic saline at 2 mL/min. During RFA, we measured the temperatures of the treated area at its center. The changes in impedance, the current and liver temperature during RFA, as well as the dimensions of the thermal ablation zones, were compared among the three groups. In the in vivo experiments, three coagulations were created by performing multipolar RFA in a pig via laparotomy with using same parameter as the ex vivo study. RESULTS In the ex vivo experiments, the impedance was gradually decreased during the RFA in groups B and C, but in group A, the impedance was increased during RFA and this induced activation by the pulsed RF technique. In groups A, B and C, the mean final-temperature values were 80+/-10 degrees C, 69+/-18 degrees C and 79+/-12 degrees C, respectively (p < 0.05). The multipolar mode created a larger volume of ablation than did the other modes: 37.6+/-4.0 cm3 (group A); 44.9+/-12.7 cm3 (group B); and 78.9+/-6.9 cm3 (group C) (p < 0.05). In the in vivo experiment, the pig well tolerated the RFA procedure and no major complications occurred during the 4 days of the follow-up period. The mean volume of coagulations produced by multipolar RFA in the pig liver was 60.5+/-17.9 cm3. CONCLUSION For the multiple probe RFA, the multipolar mode with hypertonic saline instillation was more efficient in generating larger areas of thermal ablation than either the consecutive or simultaneous monopolar modes.

Purpose: To describe the CT findings of an endobronchial metastasis from a renal cell carcinoma (RCC). Materials and methods: The CT findings and clinical features of a histologically proven endobronchial metastasis from a RCC in four patients (three male, one female; age range, 64–80 years; mean age, 69 years) were reviewed retrospectively. The location of the metastasis in the airway, shape, the degree of tumor enhancement, and the associated pulmonary parenchymal abnormalities were analyzed. Results: The histological subtype of the endobronchial metastases from the RCC was conventional in all cases. The tumors were located at the lobar ( n =1), both the lobar and segmental ( n =2), or the segmental ( n =1) bronchus. On the CT scan, the tumors were polypoid ( n =1), had a glove-finger appearance ( n =2), and exhibited branching in the airways and bronchial wall thickening ( n =1). The endobronchial metastasis from the RCC showed very high attenuation (84–128 HU), and strong enhancement (51.6–93.3 HU) on the contrast-enhanced CT images. The lung parenchymal lesions that had reticular opacities and ground glass opacities ( n =3). Conclusons: An endobronchial metastasis from a RCC appears as a strong-enhancing mass or bronchial wall thickening, accompanied by reticular opacities and ground glass opacities.

Many experimental and theoretical investigations have been carried out to examine the reduction phenomenon of compressive strength of cylindrical concrete specimens with size, but up until now, an adequate analysis technique has not been developed. In this paper, the fracture mechanics type size effect on the compressive strength of cylindrical concrete specimens was studied, with the diameter, the height/diameter ratio, and the volumetric spiral ratio of the cylinder considered as the main parameters. For this purpose, theoretical and statistical analyses were conducted. First, a size effect equation was proposed to predict the compressive strength of cylindrical concrete specimens with various diameters and height/diameter ratios. Second, the model equation derived from the plain concrete was extended for predicting the compressive strength of spirally reinforced concrete cylinders. The proposed equation showed good agreement with the existing test results for concrete cylinders with and without spiral reinforcement.

OBJECTIVE: We analyzed the diffusion and perfusion characteristics of acute MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episode) lesions in a large series to investigate the controversial changes of the apparent diffusion coefficient (ADC) that were reported in prior studies. MATERIALS AND METHODS: We analyzed 44 newly appearing lesions during 28 stroke-like episodes in 13 patients with MELAS. We performed a visual assessment of the MR images including the ADC and perfusion maps, comparison of the ADC between the normal and abnormal areas, comparison of % ADC between the 44 MELAS lesions and the 30 acute ischemic infarcts. In addition, the patterns of evolution on follow-up MR images were analyzed. RESULTS: Decreased, increased, and normal ADCs were noted in 16 (36%), 16 (36%), and 12 (27%) lesions, respectively. The mean % ADC was 102 ± 40.9% in the MELAS and 64 ± 17.8% in the acute vascular infarcts (p < 0.001), while perfusion imaging demonstrated hyper-perfusion in six acute MELAS lesions. On follow-up images, resolution, progression, and tissue loss were noted in 10, 4, and 17 lesions, respectively. CONCLUSION: The cytotoxic edema gradually evolves following an acute stroke-like episode in patients with MELAS, and this may overlap with hyper-perfusion and vasogenic edema. The edematous swelling may be reversible or it may evolve to encephalomalacia, suggesting irreversible damage.

Purpose: The purpose of this study was to compare the in-vivo efficiency of vascular occlusion on radiofrequency ablation (RFA) lesion size in a rabbit kidney model. Materials and Methods: RFA lesions were created in a single kidney in 20 rabbits using an internally cooled electrode. Twenty ablation zones (1 per kidney) were created using 4 different regimens: RFA without vascular occlusion (n = 5), RFA with renal artery occlusion (n = 5), RFA with renal vein occlusion (n = 5), RFA with renal artery and vein occlusion (n = 5). Seven days later, the rabbits were sacrificed and the lesions were excised. These groups were then compared with respect to the dimensions of the ablation zones and the changes in impedance and current during RFA. Results: The maximum ablation zone width was the greatest in the renal artery and vein occlusion group (21.0±1.4 mm), followed by the renal artery occlusion group (17.8±1.0 mm), the renal vein occlusion group (17.4±1.1 mm), and the nonocclusion group (7.8±2.4 mm) (p

Purpose: We wanted to evaluate the value of a lymph node specific MR contrast agent, Gadofluorine M, for the differentiation of hyperplastic and metastatic lymph nodes. Materials and Methods: This study included thirty-one rabbits. In ten rabbits, an injection of egg yolk or feces of rat into the calf muscles induced hyperplasia of the lymph node. In sixteen rabbits, metastasis of the lymph node was induced by implantation of VX2 tumor. Five rabbits were normal control models. We acquired the T1-, T2-weighted and SPGR coronal imaging before enhancement with 1.5 T MR. After injection of Gadofluorine M (5 mol/mL, total amount: 4 mL) interstitially into the interdigital skin fold of the hind limb, we acquired the SPGR coronal imaging at 15, 30, 60 and 90 minutes. We calculated the signal-to-noise ratios on the sequential images, and we recorded the number, size and location of the popliteal and iliac lymph nodes. Three readers assessed the state of the lymph nodes according to the pattern of enhancement: they were deemed hyperplastic nodes when totally enhanced and as metastatic nodes when there was no or partial enhancement. We also compared the imaging patterns with the histopathological results. Results: Among the 26 hyperplasia- or metastasis-induced rabbits, two rabbits were excluded because of failure to be enhanced. Histopathologic evaluation of the 24 rabbits detected one hundred seventeen lymph nodes: forty-six lymph nodes in nine hyperplasia-induced rabbits and seventy-one (metastasis in twenty-eight) lymph nodes in fifteen metastasis-induced rabbits. Out of one hundred two lymph nodes that were larger than 5 mm in size, MR enabled us to detect one hundred one lymph nodes (99.1%). The means of sensitivity, specificity, and the positive and negative predictive values for the diagnosis of lymph node metastasis by three readers were 97.6% (82/84), 98.2% (215/219), 95.3% (82/86), and 99.1% (215/217), respectively (p

The purpose of this study was to demonstrate the efficacy of bipolar radiofrequency ablation (RFA) using cooled-wet electrodes inducing coagulation in ex vivo bovine livers and in in vivo canine livers. In ex vivo experiments, 20 coagulations were created by monopolar (group A), and bipolar RFA (group B) using a 200 W generator (Valleylab) and one or two cooled-wet electrodes. In in vivo experiments, one coagulation was created by bipolar RFA in each of eight dogs via laparotomy. In ex vivo and in vivo experiments, RF was applied to one or two electrodes at 100 W for 10 min. The dimensions of the coagulations were compared in the two groups. In ex vivo experiments, the mean volumes of the coagulations produced in group B (54.0+/-16.5 cm3) were greater than those produced in group A (33.9+/-12.7 cm3) (P=0.007). In in vivo experiments, bipolar RFA produced a coagulation of 39.4+/-15.6 cm3 without a major complication. The present study showed that a RF electrode system using two cooled-wet electrodes in the bipolar mode created larger coagulation volumes than the monopolar mode, and this system can be used to create large coagulation without major complications.

Purpose: To assess and compare CT findings of surgically confirmed cases of tuboovarian abscesses (TOA) and endometriosis in order to identify indicators which may be helpful in making correct preoperative diagnoses. Materials and Methods: Of the 35 consecutive patients with surgically confirmed TOA, CT images were available for 11 of those patients. As a comparative group, 36 patients with surgically confirmed endometriosis with CT images were selected. CT images of TOA were compared with those of endometriosis. A retrospective analysis of the CT images of both groups was performed without knowledge of the pathologic diagnosis. The analysis compared the thickness and enhancement pattern of the cyst wall, attenuation of the cyst content, size and shape of the cyst, and paraaortic lymphadenopathy. Results: Mean thickness of the cyst wall was 6.2±2.0 mm in TOA and 4.5±2.4 mm in endometriosis. Multilayered appearance in both diseases was seen on enhanced CT in 91% (10/11) of TOA cases and in 25% (9/36) of endometriosis cases. Hounsefield units of the cyst contents were 20.0±5.5 HU and 24.7±10.0 HU for TOA and endometriosis, respectively. Mean diameter of the cysts was 7.5±1.7 cm in TOA and 7.9 ±3.1 in endometriosis. Shape of the cyst was multilocular in 82% (9/11) of TOA cases and in 75% (27/36) of endometriosis cases. Paraaortic lymphadenopathy was present in 73% (8/11) and 44% (16/36) for TOA and endometriosis, respectively. Conclusion: TOA should be suspected on CT when a multilocular cystic ovarian mass is observed, especially if the lesion has a thick wall and has a multilayered appearance, and is accompanied by paraaortic lymphadenopathy.