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The 2019 5th edition of the WHO classification of digestive system tumors estimates that up to 35% of hepatocellular carcinomas (HCCs) can be classified as one of eight subtypes defined by molecular characteristics: steatohepatitic, clear cell, macrotrabecular-massive, scirrhous, chromophobe, fibrolamellar, neutrophil-rich, and lymphocyte-rich HCCs. Due to their distinct cellular and architectural characteristics, these subtypes may not display arterial phase hyperenhancement and washout appearance, which are the classic MRI features of HCC, creating challenges in noninvasively diagnosing such lesions as HCC. Moreover, certain subtypes with atypical imaging features have a worse prognosis than other HCCs. A range of distinguishing imaging features may help raise suspicion that a liver lesion represents one of these HCC subtypes. In this review, we describe the MRI features that have been reported in association with various HCC subtypes according to the 2019 WHO classification, with attention given to the current understanding of these subtypes' pathologic and molecular bases and relevance to clinical practice. Imaging findings that differentiate the subtypes from benign liver lesions and non-HCC malignancies are highlighted. Familiarity with these sub-types and their imaging features may allow the radiologist to suggest their presence, though histologic analysis remains needed to establish the diagnosis.

OBJECTIVE. The purpose of this study was to evaluate the diagnostic utility of dual-layer CT (DLCT) for evaluating wrist injuries and to compare it with MRI. MATERIALS AND METHODS. The cases of 62 patients with suspected wrist fractures who underwent imaging with both DLCT and MRI from January 2018 through February 2019 were retrospectively reviewed. By means of a calcium suppression algorithm, virtual noncalcium (VNCa) image reconstruction was performed, and the images were reviewed by two readers to identify fractures, bone contusions, and nontraumatic lesions in the radius, ulna, and carpal bones. Sensitivity, specificity, PPV, and NPV were calculated and compared between standard CT and VNCa images with a combination of standard CT and MRI as the reference standard. RESULTS. Use of DLCT with VNCa reconstruction increased the sensitivity of diagnosis of fractures in the radius and carpal bones over that of standard CT alone; occult fractures were detected that were not seen with standard CT. The sensitivity and specificity for detecting radius fracture were 98.1% and 93.8% for DLCT and 96.3% and 93.8% for standard CT. For detecting carpal bone fracture, sensitivity and specificity were 100% and 98.9% for DLCT and 93.8% and 100% for standard CT. VNCa reconstruction also had good diagnostic accuracy with regard to diagnosing nonfracture bone contusions in carpal bones. The accuracy was comparable to that of MRI with sensitivity of 92.9% and specificity of 94.5%. Interreader agreement in interpreting VNCa images was generally good to excellent. CONCLUSION. DLCT with VNCa reconstruction is a promising tool for identifying occult wrist fractures and nonfracture contusion injuries in patients with wrist trauma.

OBJECTIVE. The purpose of this study was to investigate whether ancillary features can help stratify malignancy risk in Liver Imaging Reporting and Data System (LI-RADS) category 3 (LR-3) and 4 (LR-4) observations. MATERIALS AND METHODS. This retrospective longitudinal study included 106 LR-3 or LR-4 observations on gadolinium-enhanced MRI obtained from January 2014 to December 2015 in 80 patients who were treatment naïve and at risk (mean age, 58.0 ± 10.7 [SD] years; 60 men). The presence of major and ancillary features, the category determined using only major features, and the final category adjusted by the application of ancillary features were retrospectively analyzed. MRI features were compared using generalized estimating equations, and cumulative incidence curves for malignancy were compared using log-rank tests with a resampling extension. RESULTS. At 6-month follow-up, the cumulative incidence of observations initially categorized as LR-4, observations upgraded to LR-4, observations initially categorized as LR-3, and observations downgraded to LR-3 were 62.5%, 29.7%, 6.2%, and 0%, respectively. The cumulative incidence of malignancy did not differ between observations categorized by major feature as LR-3 and LR-4 ( p = 0.12), but was higher in final observations categorized as LR-4 than in those categorized as LR-3 ( p < 0.001). Among observations categorized by major feature as LR-3, the cumulative incidence of malignancy was higher in observations upgraded to LR-4 than in observations that were initially graded as LR-3 ( p = 0.03), which showed differences in the frequency of restricted diffusion and mild-to-moderate T2-weighted hyperintensity ( p < 0.001 for both). CONCLUSION. Final categories determined with ancillary features, instead of categories determined by major features only, can help indicate malignancy risk in LR-3 and LR-4 observations on MRI.

OBJECTIVE. The purpose of this study was to explore the temporal changes in fibrous dysplasia (FD) at radiographic follow-up. MATERIALS AND METHODS. A total of 138 patients with FD who had undergone extremity radiography at least twice with a minimum 12-month interval between examinations were enrolled in this study. FD was monostotic in 99 patients and polyostotic in 39 patients. Patients were also classified according to skeletal maturity as follows: Patients 16 years old or younger were classified in the skeletally immature group ( n = 34), and patients 17 years old or older were classified in the skeletally mature group ( n = 104). We compared the initial and follow-up radiographs for the following findings: lesion size, opacity, sclerotic rim, calcification, and trabeculation. RESULTS. Of the 138 patients, radiographic follow-up showed no change in lesion size in 101 patients (73.2%), progression in 31 (22.5%), and regression in six (4.3%). FD in immature bones progressed more often than FD in mature bones (23/34 [67.6%] vs 8/104 [7.7%], respectively; p = 0.000), and polyostotic FD had a greater chance of regressing than monostotic FD (4/39 [10.3%] vs 2/99 [2.0%]; p = 0.032). A temporal change in FD lesion opacity was noticed in a minority of patients (19/138, 13.8%). Variable changes were observed in the sclerotic rim, calcification, and trabeculation. CONCLUSION. The radiographic follow-up of FD showed that approximately a quarter of lesions changed in size over time. Regardless of the change in lesion size, opacity and several morphologic features of FD changed during the follow-up period, which might reflect the histopathologic evolution of FD.

Objective: The purpose of this study was to evaluate the image quality of virtual monoenergetic images obtained from dual-layer-detector spectral CT of patients with metallic orthopedic implants of the distal radius., Materials and Methods: A retrospective analysis was performed between April 2016 and January 2017. Forty-three consecutively registered patients (33 women, 10 men; mean age, 50.7 ± 15.4 years) with metallic implants for distal radius fractures underwent dual-layer-detector spectral CT. Sixteen virtual monoenergetic image sets ranging from 50 to 200 keV were generated from the single slice with the most pronounced low-attenuation artifact from implants. Image quality was quantitatively assessed on the basis of the attenuation of the artifacts and reference tissue, background image noise, and artifact index. Qualitative assessment included degree of artifact, diagnostic image quality of the periimplant bones, and delineation of fracture lines. The Friedman rank sum test and kappa analysis were used for statistical analysis., Results: There were statistically significant differences in quantitative and qualitative parameters at different monoenergy levels (all p < 0.001). Artifact index was the lowest at 120 keV. Low-attenuation artifacts in the periimplant regions were least pronounced at 110 keV, and the diagnostic image quality of periimplant bone was best at 130 keV. Fracture lines were well delineated in all cases at 80-110 keV (p < 0.001)., Conclusion: The optimal energy setting for incurring the fewest metallic artifacts and obtaining the best diagnostic image quality from distal radius implants during dual-layer-detector spectral CT is the range of 110-130 keV.

Objective: The aim of this study was to describe cuboid pulley lesions and associated abnormalities on the basis of clinical findings and the results of MRI examinations of the ankle., Materials and Methods: A retrospective search was performed to identify patients who had a cuboid pulley lesion during a 10-year period. A cuboid pulley lesion was defined as bone marrow edema in the lateroplantar ridge of the cuboid that was shown to be wrapped by the peroneus longus tendon on MRI of the ankle. A total of 19 patients (11 men and eight women; mean age, 45.4 years) were included in the group of patients with a cuboid pulley lesion, and 38 age-and sex-matched patients without a cuboid pulley lesion were randomly selected as the control group. We reviewed medical records and assessed MRI findings that could be associated with a cuboid pulley lesion., Results: The mean (± SD) diameter of the cuboid pulley lesion was 8.9 ± 4.7 mm. Cuboid pulley lesions were associated with peroneal tenosynovitis (p < 0.001), Achilles enthesitis (p = 0.004), and a clinical diagnosis of inflammatory arthritis (p < 0.001). Eleven of the 19 patients in the group with cuboid pulley lesions had inflammatory arthritis (either rheumatoid arthritis [n = 7] or spondyloarthritis [n = 4]). The cuboid pulley lesions did not cause localized lateral foot pain and tenderness, except in one patient who had an accompanying stress fracture of the cuboid., Conclusion: MRI of the ankle rarely but clearly shows cuboid pulley lesions, which themselves are not likely to cause localized pain, and cuboid pulley lesions show significant associations with peroneal tenosynovitis, Achilles enthesitis, and clinically diagnosed inflammatory arthritis.

Objective: We aimed to assess CT and 18 F-FDG PET/CT findings of colloid adenocarcinoma of the lung in seven patients., Materials and Methods: From 2010 to 2017, seven patients with surgically proven colloid adenocarcinoma of the lung were identified. CT (both enhanced and unenhanced) and PET/CT findings were analyzed, and the imaging features were compared with histopathologic reports. Clinical and demographic features were also analyzed., Results: In all cases except one, tumors showed low attenuation on unenhanced CT scans, ranging in attenuation from -16.5 to 20.7 HU (median, 9.2 HU). After contrast medium injection, enhancement was scant, so net enhancement ranged from 0.4 to 29.0 HU (median, 4.1 HU). All tumors had a lobulated contour. Stippled calcifications within the tumor were seen in one patient. The maximum standardized uptake value of tumors on PET/CT ranged from 1.5 to 4.5 (median, 3.5). In six of seven patients, FDG accumulation was seen in the tumor walls (n = 3, curvilinear uptake) or in both the tumor walls and tumor septa (n = 3, crisscross uptake). Six patients were alive without recurrence after a median follow-up period of 2.3 years (range, 2 months to 5 years). In one patient, who was alive at follow-up 4 years after imaging and had received adjuvant concurrent chemoradiation therapy after lobectomy, recurrent disease was detected 6 months after completion of the therapy., Conclusion: On CT, pulmonary colloid adenocarcinomas present as lobulated homogeneously low-attenuation tumors. At PET, curvilinear or crisscross FDG uptake is seen within the tumor where tumor cells are lining the walls or septal structures.

Objective: The purpose of this study is to evaluate the clinical effect of liver stiffness measured using MR elastography (MRE) in patients with cholestasis due to biliary obstruction., Materials and Methods: In this retrospective study, 69 consecutive patients with no history of diffuse liver disease who underwent pancreaticobiliary imaging with MRE were included. Quantitative MRI parameters (i.e., liver stiffness, apparent diffusion coefficient, R2*, and proton density fat fraction) and laboratory results (i.e., aspartate aminotransferase, alanine aminotransferase, and total bilirubin levels) were measured. Patients were classified as having either normal bilirubin (group A; n = 49) or hyperbilirubinemia (group B; n = 20). Continuous variables were compared using the independent t test or Mann-Whitney U test. Correlation between parameters was analyzed using the Pearson correlation coefficient. The ROC curve analysis was used to evaluate the diagnostic performance and clinical effect of MRE., Results: Liver stiffness was significantly higher in group B (mean ± SD, 3.8 ± 0.7 kPa) than in group A (2.8 ± 0.5 kPa) (p < 0.001); there were no differences in other MRI parameters. There were positive correlations between liver stiffness and total bilirubin (r = 0.609; p < 0.001), aspartate aminotransferase (r = 0.376; p = 0.001), and alanine aminotransferase (r = 0.285; p = 0.017) levels. There was a negative correlation between the degree of biliary decompression 1 week after bile drainage and liver stiffness (r = -0.71; p = 0.003). The sensitivity and specificity for predicting biliary decompression were 83.3% and 100%, respectively, at a liver stiffness cutoff of 4.0 kPa., Conclusion: Liver stiffness measured by MRE increases as cholestasis increases and can be a predictive factor for the sufficiency of biliary decompression after biliary drainage.

Objective: The purpose of this study was to differentiate malignant compression fractures from acute osteoporotic compression fractures of the spine by use of a Dixon MRI sequence to quantify fat fraction (FF)., Materials and Methods: Forty-four vertebral compression fractures were assessed with turbo spin-echo T1-weighted and six-echo Dixon sequences for FF quantification at 3-T MRI. The fractures were divided into malignant compression fractures (n = 24) and acute osteoporotic compression fractures (n = 20). Two radiologists independently measured quantitative parameters from ROIs in the fractures, including the T1 signal intensity of the fracture, the FF of the fracture, and the FF ratio (fracture FF divided by normal marrow FF). The mean values of the parameters were compared between the two groups, interobserver reliability between two radiologists was assessed, ROC curves were analyzed, and logistic regression analysis was performed., Results: The fracture FF and FF ratio of malignant compression fractures were significantly lower than those of acute osteoporotic compression fractures (fracture FF, 2.73% vs 14.36% [p < 0.001]; FF ratio, 0.05 vs 0.22 [p < 0.001]). There was no difference in T1 signal intensity of the fracture. The ROC AUC of fracture FF was 0.98 and of FF ratio was 0.95. In logistic regression analysis, fracture FF remained a significant variable that could be used to independently differentiate malignant from acute osteoporotic compression fractures (odds ratio, 0.33; p < 0.005)., Conclusion: FF and FF ratio obtained from FF maps obtained with a six-echo Dixon MRI sequence may be useful for differentiating acute osteoporotic compression fractures from malignant compression fractures.

Objective: The purpose of this study was to examine the associations between preoperative Liver Imaging Reporting and Data System (LI-RADS) categories and prognosis after curative resection of single hepatic malignancies in patients with chronic liver disease., Materials and Methods: Between January 2008 and December 2010, 225 patients with chronic liver disease underwent resection of single hepatic malignant tumors (218 hepatocellular carcinomas, three cholangiocarcinomas, four biphenotypic carcinomas) after undergoing gadoxetic acid-enhanced MRI. Two radiologists retrospectively categorized the tumors into LI-RADS categories. Differences in disease-free survival duration between categories were analyzed by the Kaplan-Meier method with the log-rank test., Results: Reviewer 1 categorized two (0.9%) patients as having LR-3, 53 (23.6%) LR-4, 159 (70.7%) LR-5, and 11 (4.9%) LR-M lesions. The corresponding numbers for reviewer 2 were six (2.7%) LR-3, 30 (13.3%) LR-4, 178 (79.1%) LR-5, and 11 (4.9%) LR-M. The 2-year cumulative recurrence or death rates were 15.1% for lesions categorized LR-3 or LR-4 by reviewer 1, 31.7% for LR-5, and 60% for LR-M. For lesions categorized by reviewer 2 the corresponding rates were 20.6% for LR-3 or LR-4, 29% for LR-5, and 54.5% for LR-M. Disease-free survival was significantly worse among patients with lesions categorized as LR-M than for lesions categorized as LR-3 or LR-4 or as LR-5 (p < 0.01 for both reviewers). Disease-free survival did not significantly differ between patients with LR-3 or LR-4 and those with LR-5 lesions (reviewer 1, p = 0.301; reviewer 2, p = 0.291)., Conclusion: Patients with tumors preoperatively categorized as LR-M may have a worse prognosis than those with tumors categorized LR-3, LR-4, or LR-5 after curative resection of single hepatic malignancy.

Objective: Intrahepatic cholangiocarcinoma (ICC) is a malignant tumor that arises from the intrahepatic bile ducts. Although the pathologic and imaging features of ICC have been clearly identified, recent updates have addressed the pathologic classification and imaging features of ICC using new imaging techniques. First, a proposed new pathologic ICC subclassification includes perihilar large duct and peripheral small duct ICCs. Second, advanced MR-based imaging features of ICC, such as hepatobiliary phase imaging using hepatocytespecific contrast material and DWI, have recently been described. These imaging features are important when differentiating ICCs from hepatocellular carcinomas. Finally, some imaging features of ICC, such as prominent arterial enhancement or degree of delayed enhancement, exhibit potential as prognostic imaging biomarkers., Conclusion: Comprehensive and updated knowledge of ICC is necessary for accurate diagnosis and could facilitate prediction of clinical outcomes for patients with ICC.

Objective: The purpose of this study is to describe MRI findings of muscle involvement in patients with polyarteritis nodosa (PAN), with an emphasis on the contrast enhancement characteristics., Materials and Methods: MRI studies of eight patients with PAN were retrospectively reviewed (four male and four female patients; mean age at presentation, 34.3 years; age range, 7-64 years). MR images were evaluated focusing on the following features: affected structures (muscle, fascia, or periosteum), lesion signal intensity and characteristics on T1-and T2-weighted images, and contrast enhancement patterns., Results: Seven patients had lower leg involvement, and one had thigh involvement. In the seven patients with lower leg involvement, the main lesions were within the muscles, whereas in one patient with thigh involvement, the investing fascia was mainly involved. In the seven patients with predominantly muscle involvement, T2-weighted images showed either diffuse (n = 3) or patchy (n = 4) hyperintensity of the affected muscles. On contrast-enhanced images, small fluffy enhancing lesions centered on vessels (i.e., the "cotton-wool appearance") were noted within the affected muscles in six patients. In the one patient with mainly fascial lesions, the investing fascia showed diffuse enhancement. Periosteal enhancement was found along the tibial cortex in 50% (4/8) of our patients., Conclusion: PAN should be considered a differential diagnosis in cases where MR images show patchy or diffuse muscle signal changes. Muscle involvement in PAN may show fluffy enhancing lesions centered on vessels on contrast-enhanced images and may accompany fascial or periosteal enhancement.

Objective: The objective of our study as to assess several indexes relevant to patellofemoral instability (PFI) associated with femoral trochlear dysplasia as measured on oblique coronal MR images at three standardized reference levels., Materials and Methods: A total of 30 knee MRI examinations were selected as the study group of PFI patients. Sixty knee MRI examinations were included as a control group. MRI protocols included sagittal T2-weighted, axial proton density-weighted, and oblique coronal T2-weighted imaging. On a midline sagittal image, the following three levels of the femoral trochlear groove cartilage were determined: level 1 (one-fourth level of the trochlear groove in the midsagittal plane), level 2 (one-half level of the trochlear groove in the midsagittal plane), and level 3 (three-fourths level of the trochlear groove in the midsagittal plane). Three-level axial and oblique coronal images were selected using the sagittal image as a scout. Femoral trochlear indexes including the sulcus angle, sulcus depth, facet length, and trochlear groove area were measured on the axial and oblique coronal images., Results: Most indexes showed significant differences between the PFI and control groups in the axial and oblique coronal planes at all three levels (p < 0.05). Almost all indexes measured on the oblique coronal plane images were significantly different from those measured on the axial plane images (p < 0.05). Oblique coronal images showed little variability in the sulcus angle among the three levels in contrast to a marked decrease in the angle from the proximal to distal level on axial images., Conclusion: Femoral trochlear indexes measured on oblique coronal knee MR images can be used to assess femoral trochlear dysplasia. Oblique coronal images showed less morphologic distortion of the distal femoral trochlear groove than axial images.

Objective: The purpose of this study was to identify the MRI features that aid in the differentiation between infectious sacroiliitis and unilateral sacroiliitis associated with spondyloarthritis., Materials and Methods: The MR images of 54 patients who received a diagnosis unilateral sacroiliitis between August 2001 and August 2013 were reviewed. MR images were evaluated for bone lesions (extent and distribution of bone marrow edema and presence and size of bone erosions), soft-tissue lesions (capsulitis, extracapsular fluid collections, and periarticular muscle edema), and joint space enhancement. The Fisher exact test was used for comparison of categoric data, and multivariate stepwise logistic regression analysis was performed., Results: Thick capsulitis, extracapsular fluid collection, and periarticular muscle edema were all more frequently observed in infectious sacroiliitis (p < 0.001). Iliac-dominant bone marrow edema and joint space enhancement were statistically significantly more common in spondyloarthritis (p < 0.001 and p = 0.014, respectively). The presence of periarticular muscle edema was the only independently differentiating variable on multivariate stepwise logistic regression analysis. When periarticular muscle edema was the sole predictor, unilateral sacroiliitis in spondyloarthritis was correctly identified in 77.3% of cases, and infectious sacroiliitis was correctly identified in 90.6% of cases. The overall accuracy was 85.2%., Conclusion: MRI features of the bone lesions, soft-tissue lesions, and joint space enhancement in unilateral sacroiliitis aid in the differential diagnosis between infection and spondyloarthritis. Among various findings, periarticular muscle edema was the single most important predictor of infectious sacroiliitis.

Objective: We evaluated the prognostic impact of volume-based assessment by pretreatment (18)F-FDG PET/CT in patients who had clinical stage IIIA-N2 non-small cell lung cancer (NSCLC) treated with neoadjuvant concurrent chemoradiotherapy (CCRT) followed by surgical resection., Materials and Methods: We reviewed 161 consecutive patients who had stage IIIA-N2 NSCLC treated with neoadjuvant CCRT followed by surgery. In all cases, N2 disease was pathologically confirmed by mediastinoscopic biopsy, endobronchial ultrasound-guided transbronchial needle aspiration, or video-assisted thoracoscopic surgery. We measured the total metabolic tumor volume (total MTV) and the maximum standardized uptake value (SUVmax), including a primary tumor and metastatic nodes on the pretreatment scan. Overall survival (OS) and disease-free survival (DFS) were assessed using the Kaplan-Meier method. The association of PET parameters with OS and DFS was determined by univariable and multivariable analyses performed using the Cox regression model., Results: A higher total MTV was significantly associated with poor DFS (hazard ratio [HR], 1.82; p = 0.036) and OS (HR = 2.97; p = 0.012) in the multivariable analysis. In contrast, a higher SUVmax was not significantly associated with poor DFS and OS. Patients with a high total MTV (> 22 cm(3)) had a median survival time that was significantly shorter than that of patients with a low total MTV (median DFS, 11.3 vs 42.0 months, respectively [p < 0.001]; median OS, 38.3 months vs not reached [p < 0.001]). Kaplan-Meier curves showed significant differences on the basis of total MTV in patients with or without mediastinal downstaging after CCRT. Patients with a high total MTV had significantly worse DFS when they had post-neoadjuvant pathologic (yp) stage 0-II disease (p = 0.020) or yp stage III disease (p = 0.036). Higher total MTV was also associated with worse OS in patients with yp stage 0-II disease (p = 0.013) or yp stage III disease (p = 0.007)., Conclusion: A higher pretreatment total MTV is associated with worse outcome, independent of yp stage, in patients with stage IIIA-N2 NSCLC treated with neoadjuvant CCRT followed by surgery.

OBJECTIVE. The purpose of this article is to suggest clinical indications for MRI in patients with breast cancer who have new uptake lesions in the femoral head on follow-up bone scans, by evaluating the incidence and causes of new uptake lesions. MATERIALS AND METHODS. Between January 2002 and July 2013, a total of 145 patients with breast cancer who showed new uptake in the femoral head on follow-up bone scans were included in our study. They were classified into two groups: group 1 consisted of 125 patients without known bone metastases, and group 2 consisted of 20 patients who already had bone metastases other than that in the femoral head. The Fisher exact test was performed for the statistical analysis. Thereafter, we reviewed MR images for characterization of the new abnormal uptake in the femoral head. RESULTS. New uptake lesions in the femoral head were metastatic in only 4.8% (6/125) of group 1 patients but in 75% (15/20) of group 2 patients (p < 0.0001). In both groups, no patient with a single uptake lesion in the femoral head had bone metastasis, whereas all patients with more than five new uptake lesions, including those of the femoral head, showed bone metastasis. Most MRI diagnoses for new uptake in the femoral head were fibrocystic change (15/30, 50%) and subchondral fracture (11/30, 36.7%). CONCLUSION. Most of the new uptake lesions in the femoral head detected on the follow-up bone scans in patients with breast cancer were benign. However, MRI could be considered in patients with known bone metastasis or with multiple new uptake lesions on bone scans.

Objective: The purposes of this study were to determine the prevalence of altered MRI appearances of "posterior medial meniscus root ligament (PMMRL)" lesions, introduce a classification of lesion types, and report associated findings., Materials and Methods: We retrospectively reviewed 419 knee MRI studies to identify the presence of PMMRL lesions. Classification was established on the basis of lesions encountered. The medial compartment was assessed for medial meniscal tears in the meniscus proper, medial meniscal extrusion, insertional PMMRL osseous changes, regional synovitis, osteoarthritis, insufficiency fracture, and cruciate ligament abnormality., Results: PMMRL abnormalities occurred in 28.6% (120/419) of the studies: degeneration, 14.3% (60/419) and tear, 14.3% (60/419). Our classification system included degeneration and tearing. Tearing was categorized as partial or complete with delineation of the point of failure as entheseal, midsubstance, or junction to meniscus. Of all tears, 93.3% (56/60) occurred at the meniscal junction. Univariate analysis revealed significant differences between the knees with and without PMMRL lesions in age, medial meniscal tear, medial meniscal extrusion, insertional PMMRL osseous change, regional synovitis, osteoarthritis, insufficiency fracture (p=0.017), and cruciate ligament degeneration (p<0.001)., Conclusion: PMMRL lesions are commonly detected in symptomatic patients. We have introduced an MRI classification system. PMMRL lesions are significantly associated with age, medial meniscal tears, medial meniscal extrusion, insertional PMMRL osseous change, regional synovitis, osteoarthritis, insufficiency fracture, and cruciate ligament degeneration.

Objective: The objective of our study was to determine the prevalence of thickening and signal alteration of the distal semimembranosus (SM) tendon on knee MRI and analyze the patient factors associated with abnormal MR findings of the distal SM tendon., Materials and Methods: Knee MRI scans of 116 subjects (58 men, 58 women; mean age, 48.5 years; range, 18-79 years) who underwent knee surgery were evaluated to assess the distal SM tendons in terms of signal alteration and thickness. To determine the factors associated with MR findings of the distal SM tendon, we assessed demographic characteristics; Kellgren-Lawrence radiographic osteoarthritis grading; history of trauma; the condition of the cruciate ligaments, collateral ligaments, and menisci; and whether there were cystic lesions around the SM tendon. In addition, 55 control subjects with normal knee MRI findings based on the electronic MRI patient database who had anterior knee pain and did not undergo surgery were enrolled., Results: Abnormal thickening of the distal SM tendon was found in 52.6% of knees and signal alteration in 44.8%. Univariate analysis revealed significant associations between abnormal thickening and age, body mass index, history of trauma, osteoarthritis, medial collateral ligament (MCL) thickening, and anterior cruciate ligament (ACL) tear. As for signal alteration, univariate analysis showed that age, body mass index, osteoarthritis, and MCL thickening were statistically significant factors. Multivariate binary logistic regression analyses showed that osteoarthritis and MCL thickening were the strong independent predictors in thickening and signal alteration of the distal SM tendon., Conclusion: Signal alteration and abnormal thickening of the distal SM tendon on MRI are frequently seen in daily practice. These MR findings are strongly associated with osteoarthritis and MCL thickening.

Objective: The purpose of this article is to retrospectively evaluate the imaging characteristics and outcomes of indeterminate observations (Liver Imaging Reporting and Data System category 3) detected on MRI in patients with cirrhosis., Materials and Methods: Sixty-nine indeterminate observations in 52 patients with cirrhosis were imaged with hepatobiliary contrast agent-enhanced MRI. Observations were evaluated retrospectively in terms of the location, size, enhancement pattern, and follow-up results. Each observation was categorized as stable or progressed observations according to serial follow-up MRI., Results: The mean follow-up interval was 11.2 months. Forty-six (67%) of the total observations showed arterial enhancement, and 23 (33%) observations showed isointense signal or low signal intensity on arterial phase. The indeterminate observations were classified as arterial enhancement with fade-out appearance (41 observations [59%]), arterial enhancement with washout appearance (five observations [7%]), and nonhyperenhancing observations (23 observations [33%]). Two of 69 observations (3%) were hyperintense on T2-weighted images, and four of 55 observations (7%) were hyperintense on hepatocellular phase. On the final follow-up MRI examinations, four (6%) observations proved to be probable or definite hepatocellular carcinoma, 55 (80%) remained stable, and 10 (14%) decreased in size or were no longer visible., Conclusion: The most common cause of indeterminate observations on MRI is hypervascular pseudolesions that were clinically stable on follow-up imaging.

Objective: The purpose of this study was to describe the enhancement patterns of mass-forming intrahepatic cholangiocarcinomas on gadoxetate disodium-enhanced MR images using imaging-histologic correlation., Materials and Methods: We retrospectively evaluated the preoperative gadoxetate disodium-enhanced MR images of 19 patients with mass-forming intrahepatic cholangiocarcinomas. Two readers independently interpreted enhancement patterns on arterial (globally high, rimlike), dynamic (washout, progressive), and hepatobiliary (target, nontarget) phase images. Dynamic enhancement was categorized as washout (hypoenhancement on later phase compared with arterial phase images) or progressive (persistent or gradually increased enhancement). Tumor enhancement ratio and tumor-to-liver signal difference curves were analyzed. The enhancement patterns were correlated with the extent of stromal fibrosis within the tumors., Results: Rimlike arterial enhancement (89%, reader 1; 84%, reader 2) and a progressive dynamic pattern (89%, both readers) were predominant. Tumor enhancement ratio increased gradually from the arterial to the equilibrium phase then decreased in the hepatobiliary phase, but the tumor signal intensities were lower than liver signal intensity in all phases. The two lesions that both readers considered to have globally high arterial enhancement and a washout dynamic pattern presented with minimal or scattered stromal fibrosis. Target appearance in the hepatobiliary phase (reader 1, 42%; reader 2, 47%) was more commonly seen in tumors with central stromal fibrosis (reader 1, p = 0.025; reader 2, p = 0.001)., Conclusion: Mass-forming intrahepatic cholangiocarcinomas may be characterized by rimlike enhancement and a progressive dynamic pattern on gadoxetate disodium-enhanced MR images, and these features seem related to the extent of stromal fibrosis in the tumor. Furthermore, mass-forming intrahepatic cholangiocarcinomas may have a pseudowashout pattern on gadoxetate disodium-enhanced MR images because of progressive background liver enhancement. Therefore, radiologists need to be aware of this pattern as a possible pitfall.

Objective: The purpose of our study was to assess the relationship between time intervals of CT examinations and the stages of hepatocellular carcinomas (HCCs) detected during the surveillance of patients with liver cirrhosis., Materials and Methods: In this study, 73 patients with 93 HCCs (reference standard: surgery, n=7 [8 HCCs]; biopsy, n=2 [3 HCCs]; imaging criteria, n=64 [82 HCCs]) who showed no evidence of HCC on prior CT examinations were included. Patients were stratified into three groups based on the time interval between the two CT examinations: groups A (interval≤1 year, n=21), B (interval between 1 and 2 years, n=25), and C (interval≥2 years, n=27). Tumor stages according to the American Joint Committee on Cancer (AJCC), the Barcelona Clinic Liver Cancer (BCLC) staging system, and the Milan criteria were evaluated retrospectively by two reviewers. The Fisher exact test was used to compare tumor stages. Spearman correlation coefficients were used to assess the correlation between the CT interval and tumor size., Results: One (4%) HCC in group B and four (15%) HCCs in group C were larger than 5 cm in diameter, whereas no tumor was larger than 3 cm in diameter in group A. There was no difference in tumor diameter between groups, but tumor size was positively correlated with time interval between examinations (Spearman correlation coefficient, 0.472; p<0.001). In group A, 19 (90%) patients had cancers categorized as T1, and the remaining patients had cancers categorized as T2. In group B, one (4%) patient had a cancer that was categorized as T3b according to the AJCC classification, in the intermediate stage according to the BCLC classification, and above the Milan criteria. In group C, three (11%) patients had T3b cancers, and five had cancers in either intermediate or higher stage and above the Milan criteria., Conclusion: HCC detected on CT performed within 1 year of a negative examination was at a curable stage in patients with liver cirrhosis.

Objective: Our retrospective study compared Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 with modified CT criteria to determine their respective utilities as a prognostic indicator. Using both sets of criteria, we compared treatment responses of patients with colorectal liver metastases treated with bevacizumab-containing chemotherapy with those of patients treated with chemotherapy alone., Materials and Methods: Fifty-nine patients who received bevacizumab-containing chemotherapy (n=30, group 1) or chemotherapy alone (n=29, group 2) for the treatment of colorectal carcinoma underwent contrast-enhanced CT before treatment and 2 months after treatment. Two radiologists determined changes in tumor size and density between the pretreatment and 2-month follow-up CT images. RECIST 1.1 assesses responses on the basis of changes in tumor size, and the modified CT criteria assesses responses on the basis of changes in tumor density and size. Responses were correlated with time to tumor progression by log rank test., Results: According to RECIST 1.1, nine of 30 patients (30%) in group 1 and 12 of 29 patients (41%) in group 2 were good responders. According to the modified CT criteria, 23 of 30 patients in group 1 (77%) and 23 of 29 patients in group 2 (79%) were good responders. As assessed by the modified CT criteria, good responders in both groups had significantly longer time to tumor progression than poor responders (p<0.05). As assessed by RECIST 1.1, good responders in group 1 had significantly longer time to tumor progression than poor responders (p=0.0154), but there was no difference in group 2., Conclusion: Evaluating treatment response with tumor size and density changes on CT was a better predictor of time to tumor progression than changes in tumor size alone in both groups.

Objective: The purpose of this study was to describe the CT features of gastroduodenal glomus tumors and determine the CT features differentiating glomus tumors from other subepithelial lesions., Materials and Methods: CT images of 89 pathologically proven small (≤ 5 cm) gastroduodenal glomus tumors (n = 11), gastrointestinal stromal tumors (n = 44), schwannomas (n = 15), ectopic pancreata (n = 12), and leiomyomas (n = 7) were retrospectively reviewed. For subjective analysis, location, shape, growth pattern, enhancement pattern, and presence of necrosis, calcification, and surface ulceration were analyzed. For objective analysis, the long and short diameters of the lesion, ratio of long to short diameter, thickness of the overlying layer, CT attenuation of the lesion and aorta, and lesion-to-aorta ratio in the arterial, portal venous, and equilibrium phases were measured. Among these findings, significant CT variables were determined with the chi-square, Fisher exact, and Student t tests. Receiver operating characteristic analysis was used to determine the optimal cutoff values of thickness of the overlying layer and lesion-to-aorta ratio that differentiate glomus tumor from other subepithelial lesions., Results: Typical location (antrum and duodenum), hemangioma-like enhancement pattern, overlying layer thickness 2.6 mm or greater, and portal venous phase lesion-to-aorta ratio 0.86 or greater were found to be significant variables for differentiating glomus tumors from other subepithelial lesions (p < 0.05). Among these CT findings, location and portal venous phase lesion-to-aorta ratio 0.86 or greater were highly sensitive findings for glomus tumor, and a hemangioma-like enhancement pattern was highly specific. All odds ratios were infinity. The odds ratio of overlying layer thickness of 2.6 mm or greater was 12.2 (95% CI, 2.9-51.8)., Conclusion: A subepithelial lesion with a lesion-to-aorta ratio less than 0.86 in the portal venous phase or not in the gastric antrum or duodenum is never a glomus tumor. On the contrary, a subepithelial lesion with hemangioma-like enhancement during dynamic CT is essentially a glomus tumor. On the basis of these CT findings, glomus tumor can be differentiated from other subepithelial lesions with high diagnostic accuracy.

Objective: The purpose of this study was to assess whether gadoxetate disodium-enhanced hepatobiliary phase MRI could predict the histologic factors of hepatocellular carcinomas (HCCs)., Materials and Methods: Fifty-three HCCs histopathologically proved by surgery in 51 patients were evaluated retrospectively. All patients underwent gadoxetate disodium-enhanced MRI before surgical resection. The differences in contrast enhancement ratio of the lesions and differences in contrast-to-noise ratio (CNR) among the histologic grades of HCC were compared by using the Kruskal-Wallis test. The Spearman method was used to determine the correlations among contrast enhancement ratio, CNR, cell density ratio, and positivity for anti-hepatocyte antibody, keratin 7, and keratin 19., Results: Of 53 HCCs, 50 showed low signal intensity on hepatobiliary phase images, whereas three HCCs were hyperintense on hepatobiliary phase images compared with surrounding hepatic parenchyma. Although well-differentiated HCCs tended to show higher contrast enhancement, there was no statistical significance between contrast enhancement ratio of the tumors and histologic grade (p = 0.414). No significant difference was observed between CNR and histologic grade (p = 0.965). The contrast enhancement ratios of the tumors were significantly lower in the keratin 19-positive group than in the keratin 19-negative group (p = 0.015). There was no significant correlation among contrast enhancement ratio, anti-hepatocyte antibody positivity, cell density ratio, and keratin 7 positivity (p > 0.05)., Conclusion: The contrast enhancement ratio and CNR of HCCs were not correlated with histologic grades. The contrast enhancement ratio was significantly lower in keratin 19-positive HCCs.

Objective: The purpose of this study was to define imaging features that may help characterize hyperintense lesions seen in the hepatobiliary phase of gadoxetic acid-enhanced hepatic MRI examinations., Materials and Methods: This retrospective study included 48 hyperintense nodules depicted on gadoxetic acid disodium-enhanced hepatobiliary phase MR images: 16 hepatocellular carcinomas (HCCs), 14 lesions of focal nodular hyperplasia, and 18 benign nodules associated with cirrhosis. Two observers independently reviewed hepatobiliary phase images and recorded the shape, margin, focal defects in contrast uptake, nodule-in-nodule pattern of uptake, central scar, internal septation, and presence of a hypointense rim around the lesion. Interobserver agreement was assessed with kappa statistics, and consensus opinions were reached by conference. For quantitative analysis, one observer measured lesion-to-liver contrast ratio (signal intensity of tumor divided by signal intensity of liver) on hepatobiliary phase images. Logistic regression analysis was used to determine the value of individual clinical and MR findings in prediction of malignancy., Results: Compared with benign lesions, hyperintense HCC more commonly had focal defects in uptake (68.8% vs 3.1%, respectively; p < 0.001), nodule-in-nodule appearance (75.0% vs 0%, p < 0.001), absence of a central scar (100% vs 46.9%, p < 0.001), internal septation (50.0% vs 3.1%, p < 0.001), and a hypointense rim (75.0% vs 15.6%, p < 0.001) on hepatobiliary phase MR images. The mean contrast ratios of HCC (1.31) and benign lesions (1.28) were not significantly different (p = 0.63). Multiple logistic regression analysis showed that a focal defect in contrast uptake (p = 0.025) and a hypointense rim (p = 0.019) were significant predictors of HCC, having odds ratios of 36.8 (95% CI, 1.56-870.0) and 17.5 (1.60-191.4)., Conclusion: On gadoxetic acid-enhanced MR images, hyperintense nodules can be differentiated with several imaging characteristics, especially a focal defect in contrast uptake and a hypointense rim, that indicate the diagnosis of hyperintense HCC.

Objective: The purpose of this study was to compare the diagnostic performance of MRI and endoscopic ultrasound (EUS) for the characterization of cystic pancreatic lesions and prediction of malignancy., Materials and Methods: Fifty patients (24 women and 26 men; average age, 57 years) underwent both MRI and EUS. All pancreatic lesions (21 cystic and 29 solid lesions) were proven by histopathologic analysis. Two radiologists retrospectively examined MR images, and a single gastroenterologist reviewed EUS images. The MRI and EUS characterizations of morphologic features of the cystic lesions and predictions of malignancy were evaluated. The prediction of malignancy was done by receiver operating characteristic (ROC) curve analysis., Results: There was no difference between the ability of MRI and EUS to correctly classify lesions as cystic or solid (accuracy, 90-98% vs 88%; p > 0.05). There was no difference between the sensitivity of MRI and EUS for the characterization of septa (94.4% for MRI vs 77.8% for EUS), mural nodule (66.7-58.3% for MRI vs 58.3% for EUS), main pancreatic duct dilatation (92.9-85.7% for MRI vs 85.7% for EUS), and communication with main pancreatic duct (100% for MRI vs 88.9% for EUS). The area under ROC curve values for predicting malignancy showed no statistical significance (0.755-0.774 for MRI vs 0.769 for EUS; p > 0.894)., Conclusion: MRI and EUS are comparable in the characterization of cystic pancreatic lesions and prediction of malignancy.

Objective: The purpose of our study was to determine the MRI findings of rheumatoid arthritis (RA) and tuberculous arthritis, with emphasis on differential diagnostic features., Materials and Methods: MR images of 63 joints in 62 patients with clinically or pathologically proven RA (36 joints in 35 patients) or tuberculous arthritis (27 joints in 27 patients) were evaluated retrospectively with regard to pattern and degree of synovial thickening, size of bone erosions, rim enhancement at bone erosions, degree of bone marrow and periarticular soft-tissue edema, and presence and number of extraarticular cystic masses. MRI findings were compared between RA and tuberculous arthritis by statistical analysis using kappa statistics, the Mann-Whitney U test, linear-by-linear association, and the chi-square test., Results: Nonuniform and greater degree of synovial thickening was more frequent in RA (p < 0.01); the thicker the synovial membrane, the greater the likelihood of RA (p < 0.01). Bone erosions of tuberculous arthritis were larger (p < 0.01), and the likelihood of tuberculous arthritis increased proportionally to the increment of size of the bone erosions (p < 0.01). Rim enhancement at bone erosion was more frequent in tuberculous arthritis (p < 0.01). Extraarticular cystic masses were more frequently seen and more numerous in tuberculous arthritis (p < 0.01)., Conclusion: Uniform synovial thickening, large size of bone erosion, rim enhancement at site of bone erosion, and extraarticular cystic masses were more frequent and more numerous in tuberculous arthritis. MRI may be helpful in the differentiation between RA and tuberculous arthritis.

Objective: The purpose of our study was to retrospectively investigate the MRI findings (diameter, location, contour and margin, signal intensity characteristics, and enhancement patterns) in a series of eight patients with pathologically proven colloid carcinoma of the pancreas., Conclusion: Colloid carcinomas of the pancreas appear as masses with lobulating contours, indiscrete margins, and hyperintensity on T2-weighted images (n = 8). In addition, all patients who underwent dynamic studies (n = 4) showed peripheral and internal sponge-like or mesh-like progressive delayed contrast enhancement.

Objective: The purpose of this article is to present the typical and atypical manifestations of serous cystadenoma, which can be visualized with cross-sectional imaging., Conclusion: Serous cystadenomas of the pancreas have various distinguishing imaging features. Typically, a serous cystadenoma is morphologically classified as having either a polycystic, honeycomb, or oligocystic pattern. Atypical manifestations of serous cystadenoma can include giant tumors with ductal dilatation, intratumoral hemorrhages, solid variants, unilocular cystic tumors, interval growth, and a disseminated form.

Objective: The purpose of our study was to describe the MRI findings of angioleiomyoma in the soft tissue of the extremities., Conclusion: Angioleiomyoma should be considered a possible diagnosis when a well-demarcated subcutaneous mass of isointense signal on T1-weighted images, heterogeneous high signal intensity on T2-weighted images with homogeneous strong enhancement, and an adjacent tortuous vascular structure is seen in the extremities.

Objective: The purpose of this article is to describe the roles of sonography, MDCT, MRI, and direct cholangiography in the evaluation of hilar cholangiocarcinoma., Conclusion: Hilar cholangiocarcinoma is a primary malignant tumor typically located at the confluence of the right and left ducts within the porta hepatis. Staging of hilar cholangiocarcinoma with various imaging techniques is crucial for management, and a comprehensive approach is needed for accurate preoperative assessment.

Objective: This study was designed to investigate whether the use of MR diskography would result in improved reader confidence over the use of CT diskography alone for evaluating foraminal impingement causing lumbar radiculopathy., Subjects and Methods: Sixteen disk levels in 14 consecutive patients with suspected foraminal impingement causing lumbar radiculopathy were prospectively included in the study. A mixture of diluted gadodiamide and iodinated contrast material was injected at each disk level. After diskography, a CT scan (CT diskography) and T1-weighted fat-suppressed MR image (MR diskography) were obtained. Two spine radiologists and an orthopedic spine surgeon independently scored CT diskography and MR diskography for foraminal evaluation on a 3-point scale: 1, low confidence; 2, moderate confidence; and 3, high confidence. Each reader also assessed whether MR diskography showed an additional benefit over CT diskography with regard to the depiction of foraminal abnormalities only. Another radiologist reviewed conventional MR images focused on disk height and morphology., Results: The reviewers' confidence scores for MR diskography were superior to those for CT diskography (reader 1, p = 0.00008; reader 2, p = 0.0008; reader 3, p = 0.0015) (p < 0.05). MR diskography was considered beneficial in 13 of 16 disk levels (reader 1), 14 of 16 (reader 2), and 14 of 16 (reader 3). MR diskography increased the confidence scores for the detection of foraminal impingement, especially in cases of severe disk degeneration, but did not show additional benefits in cases of an extensive vacuum in the disk or large disk extrusion., Conclusion: Simultaneous MR diskography and CT diskography with a mixture of gadodiamide and iodinated contrast material may be beneficial for evaluating foraminal impingement causing lumbar radiculopathy.

Objective: The objective of our study was to determine the diagnostic value of analyzing the pattern of gallbladder wall enhancement on MDCT to characterize diffuse gallbladder wall thickening as benign or malignant., Materials and Methods: MDCT scans obtained during the portal venous phase in 78 patients with gallbladder wall thickening caused by various pathologic conditions were retrospectively reviewed by two blinded observers. The CT features of benign and malignant gallbladder wall thickening were compared by means of univariate and multivariate analyses. The study cases were then divided into five patterns according to enhancement pattern. Using these five patterns, two radiologists reviewed the MDCT images and recorded their diagnostic confidence for differentiating benign versus malignant cause on a 5-point scale. The diagnostic performance of CT was evaluated by each observer using a receiver operating characteristic curve analysis., Results: The thicknesses of the inner and outer layers ("thick" enhancing inner layer > or = 2.6 mm, "thin" outer layer < or = 3.4 mm), strong enhancement of the inner wall, and irregular contour of the affected wall were significant predictors for a malignant cause of gallbladder wall thickening (p < 0.001). The two-layer pattern with a strongly enhancing thick inner layer and weakly enhancing or nonenhancing outer layer and the one-layer pattern with a heterogeneously enhancing thick layer were patterns that were significantly associated with gallbladder cancer (p < 0.05). When we consider those two enhancing patterns as a sign of malignancy, the diagnostic accuracy of MDCT was 89.1% and 87.6% for the two observers, respectively., Conclusion: Analyzing the enhancement pattern of a thickened gallbladder wall on MDCT is helpful in differentiating gallbladder cancer from benign inflammatory diseases.

Objective: Our study was based on our hypotheses that in idiopathic acute transverse myelitis (ATM), fractional anisotropy (FA) values would be abnormal not only in the T2-hyperintense lesion but also in the surrounding normal-appearing spinal cord and that the abnormal FA values in the spinal cord could be related to clinical outcome., Subjects and Methods: Sagittal diffusion tensor imaging (DTI) was performed in 10 patients with idiopathic ATM (four men, six women; mean age, 45 years; age range, 20-66 years) and 10 sex- and age-matched normal volunteers. FA measurements were made in the spinal cord at three levels: lesion, proximal normal-appearing spinal cord, and distal normal-appearing spinal cord. The grade of FA decrease (mild, less than 10% decrease [(FA normal - FA pt) x 100 / FA normal]; moderate, 10-20%; severe, more than 20%) was related to the clinical outcome, which was determined by a neurologist using Paine's scale of normal, good, fair, or poor., Results: Mean FA values in patients were significantly lower than those in normal volunteers in lesions (0.5328 vs 0.7125, p = 0.002) and distal normal-appearing spinal cord (0.6676 vs 0.7720, p = 0.0137). All three patients with a mild FA decrease or increase in distal normal-appearing spinal cord showed a normal or good outcome, but all three patients with a severe FA decrease in distal normal-appearing spinal cord showed a fair outcome, among the eight patients to whom steroid treatment was given., Conclusion: FA values in lesions and in distal normal-appearing spinal cord significantly decreased in patients with idiopathic ATM, and FA decrease in distal normal-appearing spinal cord might be related to clinical outcome.

Objective: Our objective was to determine the utility of 3D T2 MR cholangiography (MRC) for biliary visualization and predicting the number of ductal orifices during right lobe harvesting for ductal anastomosis in liver donors for right lobe transplantation., Materials and Methods: This study was composed of 33 donors who underwent right lobectomy for transplantation. Preoperative MRC techniques included 2D T2 MRC, 3D T2 MRC, and 3D contrast-enhanced T1 MRC. Qualitative analyses were performed for ductal visualization in each technique. The accuracies for predicting the numbers of orifices during right lobe harvesting were evaluated for 2D T2 MRC alone and for various other combined sets. MRI definitions of the predicted number of ductal orifices were compared with surgical findings., Results: Mean visualization scores of all ducts for 3D T2 MRC were significantly higher than for 2D T2 MRC and 3D contrast-enhanced T1 MRC. In predicting the number of orifices, all combined sets showed significantly higher accuracy than 2D T2 MRC. No significant difference in mean accuracies was observed within the comparison of the combined sets., Conclusion: Three-dimensional T2 MRC provided superior biliary visualization than 2D T2 MRC and 3D contrast-enhanced T1 MRC. For predicting the number of orifices, the combined set of 2D and 3D T2 MRC enabled better accuracy than 2D T2 MRC alone and produced comparable results to other combined sets.

Objective: The purpose of this study was to evaluate the MRI features of the "MR corner sign" and to determine its diagnostic usefulness in ankylosing spondylitis. We reviewed the spinal MR images of 52 patients with ankylosing spondylitis and compared these images with those of 52 age- and sex-matched control subjects., Conclusion: The MR corner sign was defined as a triangular and sharply marginated corner abnormality in a vertebral body unassociated with osteophytes or Schmorl's node. MR corner lesions were significantly more common in the ankylosing spondylitis group than in the control group (Fisher's exact test, p < 0.001). The sensitivity, specificity, and positive and negative predictive values of the MR corner sign were 44%, 96%, 92%, and 63%, respectively. The most frequent feature of signal intensity was a Modic type II change (77%). In patients with ankylosing spondylitis, the MR corner sign was fre quently seen at the thoracolumbar junction, whereas degenerative corner lesions were commonly seen in the lower lumbar spine. When the MR corner sign is detected on spinal MR images in daily practice, it should not be overlooked because it suggests the possibility of ankylosing spondylitis, which should then be further evaluated.

Objective: The objective of our study was to investigate the changes of portosystemic collaterals and splenic volume after liver transplantation and to determine the factors influencing those changes., Materials and Methods: Ninety-nine patients underwent liver CT before; immediately after (< 2 weeks); and 2, 6, and 12 months after liver transplantation. Two radiologists retrospectively reviewed the CT images to determine the grade of the portosystemic collaterals and the volume of the spleen. Portosystemic collaterals were categorized as esophageal, paraesophageal, gastric submucosal, gastric adventitial, splenic, mesenteric, or retroperitoneal varices. First, the largest diameter of each varix was determined. Each varix was graded using a 5-point scale according to the number of dilated vessels and the largest diameter. Splenic volume was calculated using a previously reported formula. To determine how varices and splenomegaly develop over time, the grade of varices on each postoperative CT scan was compared with those on the preoperative and immediately prior CT scans. The degree of change of the portosystemic collaterals and change in the splenic volume on CT were correlated with the type of transplantation (deceased-donor-related liver transplantation [DDLT] vs living-donor-related liver transplantation [LDLT]), the transplanted liver weight, and the presence of postoperative adverse events such as rejection and portal or hepatic vein stenosis., Results: All varices except splenic and retroperitoneal varices and splenic volume were significantly decreased on CT performed within 2 weeks after liver transplantation (p < 0.05). Approximately 2 months after liver transplantation, all varices except the esophageal varices and splenic volume became stable. The type of transplantation and the presence of postoperative adverse events did not affect the degree of change of varices or change in splenic volume. However, the rate of volume reduction of the spleen in LDLT was weakly but significantly correlated with the weight of the transplanted liver (Pearson's correlation coefficient, r = 0.401; p < 0.0001)., Conclusion: Most varices and splenomegaly significantly decrease during the early postoperative period (< 2 months) after liver transplantation. Patients with large liver transplants undergo a greater decrease in spleen volume than patients with small liver transplants.

Objective: The purpose of this review was to define the imaging features of colonic pseudoobstruction and to describe the pathologic findings., Conclusion: Colonic pseudoobstruction can be diagnosed on the basis of CT findings that show extensive colonic dilatation without an obstructive lesion at the intermediate transitional zone or adjacent to the splenic flexure. Pathologic examination reveals that intramural ganglion damage has a high tendency to occur in cases of chronic colonic pseudoobstruction.

Objective: The purpose of this study was to compare the performance of MRI combined with MR cholangiopancreatography (MRCP) with that of MDCT combined with direct cholangiography in the evaluation of the tumor extent and resectability of bile duct cancer with surgical and pathologic findings as the reference standard., Materials and Methods: From January 2003 to March 2006, 27 patients (18 men, nine women; mean age, 60.8 years; range, 43-80 years) with surgically proven hilar cholangiocarcinoma or common bile duct (CBD) cancer who had undergone preoperative 2D and 3D MRCP with gadolinium-enhanced MRI and triple-phase MDCT with direct cholangiography (ERCP or percutaneous transhepatic cholangiography) were included in this retrospective study. Two experienced radiologists independently reviewed the two image sets. These readers evaluated the longitudinal extent of the tumor for involvement of the secondary confluence of both intrahepatic ducts and the intrapancreatic CBD, vascular involvement of the tumor, lymph node metastasis, and tumor resectability. The radiologists' performance was evaluated by calculation of sensitivity, specificity, and overall accuracy. Correlation was made with the resected specimens or findings at surgical exploration., Results: For each reviewer, the overall accuracy rates for predicting involvement of the bilateral secondary biliary confluences and the intrapancreatic CBD were 90.7% and 87.0% for MRI with MRCP and 85.1% and 87.0% for MDCT with direct cholangiography. The differences were not statistically significant for either image set for either reviewer (p > 0.05). In the assessment of vascular involvement, lymph node metastasis, and tumor resectability, the readers' diagnostic performance using MRI with MRCP was similar to that with MDCT with direct cholangiography (p > 0.05)., Conclusion: In the diagnosis of bile duct cancer with a noninvasive procedure, the information regarding tumor extent and resectability obtained with contrast-enhanced MRI combined with MRCP is comparable with that obtained with MDCT with direct cholangiography.

Objective: The objective of our study was to evaluate the performance of MDCT in the preoperative T-staging of gallbladder cancer and to determine whether adding multiplanar reconstruction (MPR) images to axial images can improve the accuracy of MDCT for the T-staging of gallbladder cancer., Materials and Methods: Two abdominal radiologists retrospectively reviewed by consensus axial images of portal phase MDCT scans of 118 patients who had pathologically confirmed gallbladder cancers; they then reviewed the axial and MPR images from 53 of the 118 patients who had undergone MPR imaging. Local disease spread was evaluated according to the TNM system, and the results were compared with the pathologic findings using the McNemar test. The MDCT performance to differentiate each T-stage was evaluated using Fisher's exact test., Results: The sensitivities of the ability to differentiate the < or = T1 versus > or = T2 lesions, < or = T2 versus > or = T3 lesions, and < or = T3 versus T4 lesions were 79.3%, 92.7%, and 100%, respectively; the specificities were 98.8%, 86%, and 100%, respectively (p < 0.0001). The overall accuracy for the T-stage was 83.9%. In the 53 patients with MPR images, the combined reading of the axial and MPR images increased the diagnostic accuracy compared with axial image reading only from 71.7% to 84.9%, a statistically significant degree (p = 0.0233)., Conclusion: MDCT provided 83.9% accuracy in the diagnosis of the local extent of gallbladder carcinomas, thereby showing acceptable sensitivity and specificity. The addition of MPR images to the axial CT data increased the accuracy.

Objective: Our purpose was to evaluate the usefulness of integrated 18F-FDG PET/CT in the detection and characterization of nonpalpable supraclavicular lymph node metastasis in patients with the initial diagnosis of lung cancer., Subjects and Methods: This study was conducted from May 2005 to May 2006 and included 32 consecutively registered lung cancer patients in whom supraclavicular lymph nodes were not palpable but were identified on contrast-enhanced CT or exhibited increased FDG uptake on integrated PET/CT. Three patients had bilateral nodes, for a total of 35 nodes in the 32 patients. Results of cytologic analysis of a specimen obtained with sonographically guided fine-needle aspiration (n = 27), normal initial and follow-up sonographic findings (n = 3), and no change in the size of supraclavicular lymph nodes on follow-up sonography (n = 2) were the reference standards. The presence of supraclavicular lymph node metastasis was determined with integrated PET/CT (uptake greater than that of surrounding tissue) and contrast-enhanced CT (node short-axis diameter of 5 mm or more). The diagnostic efficacies of these methods in the detection of supraclavicular lymph node metastasis were compared., Results: Supraclavicular lymph node metastasis was diagnosed cytologically in 12 (34%) of 35 lesions. The diagnostic accuracies of integrated PET/CT and contrast-enhanced CT in the detection of supraclavicular lymph node metastasis were 71% and 66%, respectively; the difference was not statistically significant. Although the difference was not statistically significant, the sensitivity (92%) and negative predictive value (93%) of integrated PET/CT were higher than those of contrast-enhanced CT., Conclusion: Because of its high sensitivity and negative predictive value, integrated PET/CT is useful in the detection and characterization of nonpalpable supraclavicular lymph nodes in lung cancer patients.

Objective: The purpose of this study was to describe retrospectively integrated PET/CT findings on pulmonary neuroendocrine tumors and to correlate the findings with prognosis., Materials and Methods: Between May 2003 and February 2005, 37 consecutively enrolled patients (33 men and four women; mean age, 60 years) with histopathologically proven pulmonary neuroendocrine tumors underwent 18F-FDG PET/CT after enhanced standalone CT. CT was used to analyze the morphologic features of the tumors and PET to measure maximum standardized uptake value (SUV). Maximum SUVs of carcinoid tumors, large-cell neuroendocrine carcinomas (LCNECs), and small-cell lung carcinomas (SCLCs) were compared, and maximum SUV and tumor stage and prognosis were correlated., Results: Four (two typical and two atypical) of the seven carcinoid tumors had no FDG uptake or less than mediastinal uptake. The maximum SUVs of primary tumors, in increasing order, were significantly different for carcinoids (mean, 4.0; median, 3.4), LCNECs (mean, 12.0; median, 10.7), and SCLCs (mean, 11.6; median, 11.7) (p = 0.006, Kruskal-Wallis test). There was no significant correlation between maximum SUV of the primary tumor and the tumor stages of carcinoids, LCNECs, or SCLCs (p = 0.08, Jonckheere-Terpstra test; p = 0.768, Mann-Whitney test). Results of receiver operating characteristics analysis showed a maximum SUV greater than 13.7 suggested a poor survival period in cases of LCNEC and SCLC., Conclusion: The maximum SUVs of neuroendocrine tumors are significantly different for carcinoid tumors, LCNECs, and SCLCs, and a high maximum SUV suggests short survival of patients with LCNEC or SCLC.

Objective: The objective of our study was to compare CT image interpretation using PACS tile and multisynchronized stack modes with respect to speed and observer performance for the detection of hepatocellular carcinoma (HCC) in liver transplant candidates., Materials and Methods: Institutional review board approval was obtained, but informed consent was not required for this retrospective study. Sixty-seven patients underwent dynamic multiphasic CT within 3 months before liver transplantation. Interval reviews using tile and multisynchronized stack modes were performed independently by four reviewers with various levels of experience to determine the presence of HCC using a five-point confidence scale. Observer performance was compared using jackknife free-response receiver operating characteristic (ROC) analysis. The time required to interpret the CT scans using each mode was recorded and compared using the paired Student's t test., Results: Twenty-seven patients had 48 HCC nodules. The mean free-response ROC figures of merit for detecting HCC were significantly higher using the multisynchronized stack mode (0.731) than using the tile mode (0.662) (F-statistic = 6.603, p = 0.012). The 95% CIs for the task were -0.125 - -0.016. The time used for image analysis was also significantly shorter with the stack mode (63 to approximately 75 seconds) than with the tile mode (94 to approximately 191 seconds) for all four reviewers (p < 0.0001)., Conclusion: Multisynchronized stack viewing of multiphasic dynamic CT scans significantly increases the detection rate of HCC in liver transplant candidates. It also significantly shortens the interpretation time compared with tile viewing.

Objective: The objectives of this retrospective study were to assess the therapeutic effect of transforaminal epidural steroid for sciatica and to identify outcome predictors., Materials and Methods: Transforaminal epidural steroid injections were performed in 248 patients from June 2003 to May 2004. Fifty-six patients (33 women, 23 men; mean age, 53.3 years; age range, 30-83 years) were included. Therapeutic effects were evaluated 2 weeks after injection. The possible outcome predictors were as follows: intraepineural or extraepineural injection, saddle-type distribution pattern (contrast material distributed rostrally to the epidural portion of the preganglionic nerve root) or not saddle type, cause of sciatica (spinal stenosis vs herniated disk), patient age, patient sex, and duration of sciatica (acute or subacute [< 6 months] vs chronic [> 6 months]). The relationships between possible outcome predictors and therapeutic effects were analyzed. Statistical analysis was performed using Fisher's exact test, the chi-square test, and multiple logistic regression analysis., Results: Forty-three (76.8%) of the 56 patients achieved a satisfactory result 2 weeks after transforaminal epidural steroid injection. Nineteen (65.5%) of the 29 patients treated by intraepineural injection and 24 (88.9%) of the 27 patients treated by extraepineural injection achieved a satisfactory result, and this difference was significantly different (p < 0.05). Other possible predictors of a better outcome were identified--that is, saddle-type pattern of contrast distribution, a herniated disk, and sciatica of less than 6 months' duration. Multiple regression analysis showed that the only factor significantly associated with outcome was the type of injection (p = 0.04, odds ratio: 5.01)., Conclusion: Transforaminal epidural steroid is an effective tool for managing sciatica, and an extraepineural injection may be a predictor of a better outcome for sciatica treated using transforaminal epidural steroid.

Objective: The objective of our study was to determine the optimal TE for superparamagnetic iron oxide (SPIO)-enhanced gradient-recalled echo (GRE) MRI for the detection of focal hepatic lesions., Materials and Methods: Ferucarbotran-enhanced GRE sequences, performed on a 1.5-T MR system, were used to evaluate 131 lesions (38 hepatocellular carcinomas, 37 metastases, 21 hemangiomas, 7 cholangiocarcinomas, 15 cysts, and 13 miscellaneous lesions) at four different TEs: 9, 13.5, 18, and 22.5 milliseconds. The lesion-to-liver signal difference-to-noise ratio (SDNR) was compared among the four GRE sequences by paired Student's t tests and among lesion types by an independent samples Student's t test. The McNemar test was used to compare the sensitivity for the detection of focal hepatic lesions. Wilcoxon's signed rank test was used to compare the subjective lesion conspicuity., Results: The SDNRs of lesions on GRE images obtained at a TE of 13.5 milliseconds (mean +/- SD, 60 +/- 24) were significantly (p < 0.001) higher than those at TEs of 9 (55 +/- 23), 18 (55 +/- 22), and 22.5 milliseconds (47 +/- 19). The SDNR was highest at a TE of 13.5 milliseconds for SPIO-uptake lesions and was comparable on images obtained with TEs of 18 and 13.5 milliseconds for non-SPIO-uptake lesions. The non-SPIO-uptake lesions showed a significantly higher SDNR than the SPIO-uptake lesions at a TE of 22.5 milliseconds (p = 0.007). The overall sensitivity for lesion detection was not significantly different among the four GRE sequences, and the subjective ratings of lesion conspicuity were comparable for images obtained using TEs of 8, 13.5, and 18 milliseconds, but the ratings of lesion conspicuity were significantly lower for images obtained using a TE of 22.5 milliseconds (p < 0.001)., Conclusion: For ferucarbotran-enhanced MRI, lesion SDNR was highest on images obtained using a TE of 13.5 milliseconds, but the sensitivity and lesion conspicuity were comparable at TEs of 9 and 18 milliseconds. The SDNR of liver lesions varied according to the lesion's potential capability of taking up SPIO agents.

Objective: The purpose of this pictorial essay is to illustrate the various appearances of solid pseudopapillary tumor of the pancreas., Conclusion: Solid pseudopapillary tumor of the pancreas is a rare neoplasm usually found in young women. Typical solid pseudopapillary tumor is characterized by a well-encapsulated mass with varying amounts of intratumoral hemorrhage. However, the tumor can have an atypical appearance, such as metastasis, ductal obstruction, parenchymal and extracapsular invasion, simulation of islet cell tumor, intratumoral calcification, and occurrence in a male patient. The typical and atypical manifestations of solid pseudopapillary tumor can be visualized with cross-sectional imaging.

Objective: The purpose of this study was to define the optimal scan window for acquiring arterial phase images in the detection of hypervascular hepatocellular carcinomas (HCCs)., Materials and Methods: Biphasic arterial phase CT examinations were performed using a 16-MDCT scanner on 198 patients (159 men and 39 women; mean age, 59 years; age range, 25-82 years) with nodular HCC. All examinations were performed after administering 120-150 mL of a nonionic contrast media (370 mg I/mL) at a rate of 3-4 mL/s. The scan delay--the interval between when the bolus-tracking program detected the threshold enhancement of 100 H in the abdominal aorta and the start of the first arterial scan-was progressively lengthened by 2-second intervals, from 10 seconds in group 1 to 20 seconds in group 6. The second arterial phase scan was started 6 seconds after the end of the early scan. A tube collimation of 1.5 mm, a table feed of 18 mm per rotation, an image thickness of 3 mm, and 3-mm increments were used. The duration of each phase scan was 4.5-8.8 seconds. Tumor-to-liver attenuation difference (TLAD) at the first (TLAD1) and second (TLAD2) arterial phase images were compared lesion by lesion. Four observers assigned subjective ratings of visual conspicuity and individual preferences for each phase in each group., Results: The mean threshold time (100 H) was 18.4 +/- 3.1 seconds, and 97% of patients were within the range of 13-24 seconds. The mean TLAD1 of groups 3 to 6 and the mean TLAD2 of groups 1 to 5 were all comparable; they were also all significantly (p < 0.005) higher than the mean TLAD1 of groups 1 and 2 and the mean TLAD2 of group 6. In groups 1 and 2, the mean TLAD2 was significantly higher than the mean TLAD1 (p < 0.001); in groups 5 and 6, the mean TLAD1 was significantly higher than the mean TLAD2 (p < 0.001). In groups 3 and 4, the mean TLAD1 and TLAD2 were similar. The visual conspicuity and individual preferences were higher for the first-phase image in groups 3 to 6 and the second-phase image in groups 1 and 2., Conclusion: The optimal scan window for arterial phase images in the detection of HCC seems to be approximately 14-30 seconds from the 100-H threshold.

Objective: Our aim was to describe the MRI findings of subcutaneous epidermal cysts with an emphasis on determining the presence of rupture., Conclusion: Epidermal cysts show a fluidlike signal with variable low-signal components on T2-weighted images and peripheral rim enhancement on gadolinium-enhanced images. Most ruptured cysts have septa, show thick and irregular rim enhancement, and are accompanied by a fuzzy enhancement in surrounding subcutaneous tissues. These imaging features of a ruptured epidermal cyst simulate a mass of infectious or neoplastic origin.