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Background Noninvasive diagnostic guidelines for hepatocellular carcinoma (HCC) vary across different global geographic areas, especially regarding criteria about gadoxetic acid-enhanced MRI. Purpose To compare the diagnostic performance of four different international HCC diagnosis guidelines and readers' judgment in diagnosing HCC using gadoxetic acid-enhanced MRI in patients at high risk for HCC. Materials and Methods This retrospective study included patients who had not undergone treatment, were at risk for HCC, and who underwent gadoxetic acid-enhanced MRI from January 2015 to June 2018 from 11 tertiary hospitals in South Korea. Four radiologists independently reviewed focal liver lesions (FLLs) according to four guidelines: American Association for the Study of Liver Diseases (AASLD)/Liver Imaging Reporting and Data System (LI-RADS), Korean Liver Cancer Association-National Cancer Center (KLCA-NCC), European Association for the Study of the Liver (EASL), and Asian Pacific Association for the Study of the Liver (APASL). Reader judgment (HCC or not HCC) was also recorded. Malignant FLLs were confirmed at pathology, and histologic and clinical follow-up data were used for benign FLLs. The guidelines' diagnostic performance was compared using generalized estimating equations. Additionally, the diagnostic odds ratio was assessed. Results A total of 2445 FLLs (median size, 27.4 mm) were analyzed in 2237 patients (mean age, 59 years ± 11 [SD]; 1666 male patients); 69.3% (1694 of 2445) were HCCs. KLCA-NCC showed the highest accuracy (80.0%; 95% CI: 78.7, 81.2; P = .001), with high sensitivity in Eastern guidelines (APASL, 89.1% [95% CI: 87.8, 90.3]; KLCA-NCC, 78.2% [95% CI: 76.6, 79.7]) and high specificity in Western guidelines (AASLD/LI-RADS, 89.6% [95% CI: 87.8, 91.2]; EASL, 88.1% [95% CI: 86.2, 89.9]) ( P = .001). The diagnostic odds ratios were 20.7 (95% CI: 17.0, 25.3) for AASLD/LI-RADS, 18.9 (95% CI: 15.8, 22.6) for KLCA-NCC, 16.8 (95% CI: 13.8, 20.4) for EASL, and 8.9 (95% CI: 7.4, 10.7) for APASL. The readers' judgment demonstrated higher accuracy than that of the guidelines (accuracy, 86.0%; 95% CI: 84.9, 86.9; P = .001). Conclusion Among four different international HCC diagnosis guidelines, Eastern guidelines demonstrated higher sensitivity, whereas Western guidelines displayed higher specificity. KLCA-NCC achieved the highest accuracy, and AASLD/LI-RADS exhibited the highest diagnostic odds ratio. © RSNA, 2024 Supplemental material is available for this article.

Twelve patients with symptoms of acute cholecystitis underwent heavily T2-weighted and mangafodipir trisodium-enhanced T1-weighted magnetic resonance (MR) cholangiography and cholescintigraphy before they underwent cholecystectomy. On T2-weighted MR cholangiographic images, morphologic evidence of outflow obstruction of the gallbladder was definitive in seven patients, equivocal in one, and absent in four. In all 12 patients, biliary dynamics depicted at manganese-enhanced T1-weighted MR cholangiography agreed completely with those depicted at hepatobiliary scintigraphy. T2-weighted MR cholangiography combined with manganese-enhanced T1-weighted MR cholangiography provides not only morphologic information but also functional information about the biliary system., (Copyright RSNA, 2003)

Purpose: To describe the magnetic resonance (MR) imaging appearance of anterior cruciate ligament (ACL) stump entrapment in patients who presented with decreased knee extension after rupturing the ACL., Materials and Methods: MR images in 15 patients who had presented with a block to terminal knee extension after sustaining an ACL tear were retrospectively reviewed. The MR imaging appearances of entrapped ACL stumps were defined and correlated with arthroscopic and histologic findings., Results: The entrapped ACL stumps had two distinct appearances. Type 1 stumps (n = 11) were characterized by a nodular mass located at the anterior aspect of the intercondylar notch, interposed between the lateral femoral condyle and tibia. Type 2 stumps (n = 4) were characterized by a tonguelike free end and angulation of the stump. Histologic evaluation of the resected specimens showed distorted ACL fibers intermixed with variable fibrosis and inflammation., Conclusion: Entrapment of an ACL stump can limit knee extension. The two observed appearances of entrapped ACL stumps likely represent two points along a spectrum of appearances, which possibly includes the cyclops lesion., (Copyright RSNA, 2002)

Purpose: To assess the capability of helical computed tomography (CT) to assist in the differentiation between mucinous and nonmucinous gastric carcinomas, with a focus on the thickened stomach wall itself., Materials and Methods: In 62 patients with pathologically proved mucinous (n = 21) or nonmucinous (n = 41) gastric carcinomas, contrast material-enhanced helical CT images were obtained. The gross appearance, contrast enhancement pattern, predominant thickened layer, and degree of enhancement were retrospectively evaluated. Statistical analyses were performed with Fisher exact, chi(2), and Student t tests. A P value of less than.05 was considered to indicate a statistically significant difference., Results: The most common type of gross appearance in both carcinomas was fungating: It occurred in 71% of patients with mucinous carcinomas and in 59% of patients with nonmucinous carcinomas. The next most common gross appearance type was ulcerative (24% of patients) in nonmucinous carcinomas and diffusely infiltrative (29% of patients) in mucinous carcinomas (P =.009). The most common contrast enhancement pattern was homogeneous (61% of patients) in nonmucinous carcinomas and layered (62% of patients) in mucinous carcinomas (P =.001). These findings were significantly different. The predominantly affected thickened layer was the high-attenuating inner layer or the entire layer (88% of patients) in nonmucinous carcinomas and the low-attenuating middle or outer layer (57% of patients) in mucinous carcinomas. Only two mucinous tumors showed miliary punctate calcifications in infiltrative lesions., Conclusion: Helical CT may assist in distinguishing mucinous from nonmucinous gastric carcinoma, primarily on the basis of enhancement pattern, predominant layer of the thickened wall, gross appearance, and presence of calcifications., (Copyright RSNA, 2002)

Purpose: To document the computed tomographic (CT) findings of transcatheter arterial chemoembolization (TACE)-induced, localized bile duct injuries leading to portal vein branch obliteration in the liver and to elucidate the clinical implications with retrospective review of the authors' experiences., Materials and Methods: Follow-up CT scans obtained in 11 patients with TACE-induced intrahepatic bile duct dilatation were reviewed retrospectively to evaluate serial changes in the adjacent portal vein branches and hepatic parenchyma. Clinical data, including time between TACE and CT and serum alkaline phosphatase levels, also were analyzed., Results: Of 11 patients with marked (n = 8) or mild (n = 3), lobar (n = 4) or segmental (n = 7) bile duct dilatation with or without bile collection in the tissue sheaths of the Glisson capsule or hepatic parenchyma, nine (82%) had bile duct changes at the first CT follow-up, within 1 month after TACE. Marked narrowing or obliteration of the adjacent intrahepatic portal vein branches in 10 (91%) patients resulted in progressive atrophy of the corresponding hepatic parenchyma in nine (82%) at variable times after TACE. The serum alkaline phosphatase level increased to more than 200 U/L in eight (89%) of nine patients 1 month after TACE., Conclusion: TACE-induced intrahepatic bile duct injury resulting in obliteration of the adjacent portal vein branch seems to be one cause of hepatic parenchymal atrophic changes after TACE.

Purpose: To compare the accuracy of magnetic resonance (MR) cholangiography with that of direct cholangiography for the evaluation of recurrent pyogenic cholangitis., Materials and Methods: Twenty-four patients with recurrent pyogenic cholangitis underwent MR cholangiography before surgery, and 18 of these 24 also underwent direct cholangiography. Two reviewers evaluated MR cholangiograms and direct cholangiograms and focused on identifying intrahepatic ductal dilatation, stricture, and calculi, as well as coexistent parenchymal abnormalities, on the basis of the classification of the internal lobes and segments of the liver. These observations were compared with surgical findings., Results: According to examination results in the surgical specimens, 24 patients had 46 segmental abnormalities. MR cholangiography depicted all 46 (100%) segments with ductal dilatation, 22 (96%) of 23 segments with focal ductal stricture, and 43 (98%) of 44 segments with ductal calculi. Eighteen patients who underwent direct cholangiography had 32 segmental abnormalities according to examination results in the surgical specimens. Direct cholangiography depicted 15 (47%) of 32 segments with ductal dilatation, eight (44%) of 18 segments with focal ductal stricture, and 14 (45%) of 31 segments with ductal calculi., Conclusion: MR cholangiography is superior to direct cholangiography for accurate topographic evaluation of recurrent pyogenic cholangitis because it is able to depict all of the biliary tree, despite obstruction or stenosis.

Purpose: To determine the magnetic resonance (MR) imaging findings of small nontumorous hepatic arterial-portal venous (arterioportal) shunts in the liver., Materials and Methods: MR images in 25 patients with 38 small nontumorous arterioportal shunts verified with surgery or follow-up imaging were included in this study. The causes of arterioportal shunts were iatrogenic causes in 11 patients and/or cirrhotic changes in the remaining patients. Nonenhanced T1- and T2-weighted images and multiphase contrast material-enhanced dynamic images were retrospectively reviewed and compared with conventional hepatic arteriograms to determine the MR characteristics related to the focal hemodynamic changes., Results: On arterial-dominant-phase dynamic MR images, 29 (76%) of the 38 arteriographically suggested nontumorous arterioportal shunts displayed abnormal findings distinguished against the surrounding hepatic parenchyma, including wedge-shaped (n = 14), nodular (n = 9), or irregularly outlined (n = 6) areas of focal contrast enhancement. The signal intensity on nonenhanced T1- and T2-weighted images of the corresponding areas appeared unremarkable except for three wedge-shaped high-signal-intensity areas (three [8%] of 38) on T2-weighted images accompanied by prolonged contrast enhancement. Most (24 [83%] of 29) areas of abnormal signal intensity were located at the periphery of the liver parenchyma., Conclusion: A small nontumorous arterioportal shunt should be considered one of the causes of focal parenchymal hyperperfusion abnormalities on contrast-enhanced dynamic MR images of the liver in the absence of abnormal signal intensity on static MR images.

Purpose: To determine whether temporal parenchymal enhancement around hepatic cavernous hemangiomas can be correlated with the rapidity of intratumoral contrast material enhancement and/or tumor volume at dynamic magnetic resonance (MR) imaging., Materials and Methods: Dynamic MR images obtained in 94 patients with 167 hemangiomas were retrospectively reviewed for peritumoral enhancement. Tumor volume was estimated by using the longest dimension on nonenhanced images. Speed of intratumoral contrast material enhancement was determined with early nonequilibrium phase images and was categorized as rapid (>75% of tumor volume), intermediate (25%-75% of tumor volume), or slow (<25% of tumor volume)., Results: Thirty-two of the 167 hemangiomas (19%) had temporal peritumoral enhancement, which was more common in hemangiomas with rapid enhancement (20 of 49 [41%]) than in those with intermediate (12 of 62 [19%]) and slow (0 of 56 [0%]) enhancement (P: <.001). The mean diameter of the hemangiomas with peritumoral enhancement was not significantly different from that of hemangiomas without peritumoral enhancement (P: >.05). Hemangiomas with rapid enhancement (mean diameter, 16 mm +/- 8), however, were significantly smaller than those with intermediate enhancement (mean diameter, 33 mm +/- 34) (P: <.001)., Conclusion: Temporal peritumoral enhancement on dynamic MR images of hepatic hemangiomas correlates well with the speed of intratumoral contrast material enhancement and was most commonly encountered in rapidly enhancing small lesions. There was no statistically significant relationship, however, between peritumoral enhancement and tumor volume.

Purpose: To evaluate the clinical usefulness of magnetic resonance (MR) cholangiography in the assessment of acute cholecystitis by comparing the diagnostic accuracy of MR cholangiography with that of ultrasonography (US)., Materials and Methods: Thirty-five patients with symptoms of acute cholecystitis underwent both US and MR cholangiography before cholecystectomy, which helped confirm acute cholecystitis. Two reviewers evaluated US and MR cholangiographic images for evidence of calculi and gallbladder wall thickening and compared these findings with surgical findings., Results: MR cholangiography depicted all 21 (100%) calculi and one false-positive calculus in the cystic duct and gallbladder neck, but US depicted only one (14%) of seven cystic duct calculi and 12 (86%) of 14 gallbladder neck calculi. In the diagnosis of cystic duct obstruction, MR cholangiography had a sensitivity of 100%, a specificity of 93%, and an accuracy of 97%. US had a sensitivity of 62%, a specificity of 100%, and an accuracy of 77%. In the diagnosis of gallbladder wall thickening, MR cholangiography had a sensitivity of 69%, a specificity of 83%, and an accuracy of 71%. US had a sensitivity of 96%, a specificity of 83%, and an accuracy of 94%., Conclusion: In the assessment of acute cholecystitis, US is superior to MR cholangiography in the evaluation of gallbladder wall thickening. However, MR cholangiography is superior to US in the depiction of cystic duct and gallbladder neck calculi at the evaluation of cystic duct obstruction.

Purpose: To evaluate the cross-sectional imaging features of osteochondral defects (OCDs) of the glenoid fossa and to elicit a more detailed analysis of the trauma, if any, that may cause this injury., Materials and Methods: Eight patients (seven male patients, one female patient; age range, 15-42 years; mean age, 27 years) with an OCD in the glenoid fossa were identified. Conventional computed tomography (CT), CT arthrography, or magnetic resonance (MR) imaging was performed. Surgical correlation was available in six patients., Results: Six patients had a history of anterior dislocation or subluxation, one patient had an acromioclavicular joint separation, and one patient had chronic pain. Seven patients had anterior labral tears, and four had a redundant capsular insertion. A glenoid OCD appeared as either a multiloculated cyst in the subchondral bone mimicking a subchondral cyst (six patients) or a single osteochondral fragment (two patients). The lesion ranged from 8 mm to 2.0 cm in diameter. Three patients had an intraarticular body. Surgery confirmed an OCD in six of six patients., Conclusion: A glenoid OCD occurs most often as a result of acute trauma and has a high association with instability, labral tear, and intraarticular bodies.

Purpose: To compare hepatic angiographic findings of small arterial-portal venous shunts with those of other imaging modalities, and to determine whether these shunts are related to hepatocellular carcinoma., Materials and Methods: At hepatic angiography in 223 patients, small arterial-portal venous shunts not directly related to hepatocellular carcinoma and focal areas of parenchymal contrast material enhancement more than 1 cm in diameter were found in 28 patients. These 28 patients were prospectively evaluated with computed tomography (CT) during arterial portography (CTAP) (n = 12), CT after iodized oil administration (n = 23), intraoperative ultrasonography (n = 5), or follow-up hepatic angiography (n = 13). Magnetic resonance (MR) images (n = 10) and dynamic CT scans (n = 4) in these patients were retrospectively reviewed., Results: Arterial-portal venous shunts noted at angiography manifested as perfusion defects at CTAP in 10 patients and as an area of arterial contrast enhancement at dynamic CT in three patients. No lesion was seen at MR imaging, and no persistent iodized oil uptake was seen at CT. There was no evidence of hepatocellular carcinoma tumor growth around the shunts at follow-up angiography, and no tumor was present at surgery., Conclusion: Understanding of the hemodynamic changes caused by these small shunts can aid in the interpretation of vascular imaging findings.

Purpose: To determine the prevalence of a meniscal flounce, the magnetic resonance (MR) imaging characteristics, and whether the flounce is associated with a meniscal tear., Materials and Methods: Knee MR images obtained in 3,159 examinations over 2 years were prospectively evaluated. Ten adult patients (six with true flounces, four with flouncelike folds associated with meniscal tears) with an S-shaped fold in the free edge of a meniscus on sagittal images were included. Five underwent arthroscopic surgery., Results: The prevalence of a flounce was 0.2% (six of 3,159 examinations). Five occurred in the medial meniscus (MM) and one occurred in the lateral meniscus (LM). All appeared truncated in the coronal plane. Four meniscal tears also demonstrated flouncelike folds. Three were confirmed with surgery and one was confirmed with clinical findings. Of the 3,159 MR examinations, 1,151 demonstrated an MM tear, 832 an LM tear, 542 MM degeneration, and 270 LM degeneration., Conclusion: A meniscal flounce is a fold that occurs in the absence of a tear, and presence of it does not increase the prevalence of a tear. Because tears may result in a flouncelike fold, a flounce should be considered a normal variant only in the absence of other indications of a meniscal tear.

Purpose: To determine if angling the coronal plane in magnetic resonance (MR) imaging of the knee increases the conspicuity of the posterolateral structures., Materials and Methods: A coronal oblique MR imaging sequence performed parallel to the popliteal tendon proximally was added to our routine study in patient knee examinations. One hundred patients (age range, 12-72 years) underwent MR imaging., Results: Coronal oblique images depicted the arcuate ligament in 46%, the fabellofibular ligament in 48%, and the fibular origin of the popliteal muscle in 53% of the patients, whereas standard coronal images depicted these in 10%, 34%, and 8% of the patients, respectively. Sagittal oblique images did not adequately depict these structures., Conclusion: Depiction of the structures in the posterolateral aspect of the knee was optimal on coronal oblique images. We advocate obtaining coronal oblique T2-weighted images in patients with either posterolateral knee pain or suspected injury to the posterolateral ligamentous structures.

Purpose: To demonstrate the plantar compartments of the foot on magnetic resonance (MR) images., Materials and Methods: The plantar compartments of four cadaveric feet underwent MR imaging and were sectioned. Fifteen MR studies in 11 patients with compartmental fluid were evaluated. The epicenter of infection was determined from review of the history, radiographs, and MR images., Results: In the cadaveric feet, distribution of contrast material conformed to the compartmental anatomic features. MR findings in the specimen correlated exactly with gross findings. All seven feet with infection centered at the second through fourth metatarsal heads demonstrated only central compartment fluid. In seven of eight feet with a more medial or lateral epicenter of infection, fluid was seen in the lateral or medial compartment and in the central compartment. In one foot with a lateral epicenter of infection, fluid was confined to the lateral compartment., Conclusion: MR imaging accurately depicts the compartmental anatomic features of the foot.