Young Jun Kim

PURPOSE: To compare the diagnostic performance of multirow-detector computed tomography (MDCT) and magnetic resonance imaging (MRI) in the differentiation of intraductal papillary mucinous neoplasms (IPMNs) from other pancreatic cystic masses. MATERIALS AND METHODS: A total of 53 patients with pathologically proven pancreatic cystic lesions who had undergone MDCT and MRI were included in this study. Two radiologists analyzed the morphologic features of the lesions and graded the lesion conspicuity on each examination. The readers assigned their confidence level regarding the differentiation of IPMN from other lesions and predicting ductal communication of the lesion. The radiologists' diagnostic confidence was compared using receiver operating characteristic (ROC) analysis. RESULTS: The Az values for each observer for predicting ductal communication of the lesion and differentiating IPMN from other lesions were as follows: For MRI they were respectively 0.949 and 0.995 for reader 1, and 0.916 and 0.932 for reader 2. For MDCT they were respectively 0.790 and 0.875 for reader 1, and 0.774 and 0.850 for reader 2. In addition, for differentiating IPMNs from other lesions, MRI was significantly more accurate than MDCT (P < 0.05) for one observer, but for the other observer there was no significant difference between the two examinations (P = 0.059). For predicting ductal communication of the cystic lesions for both observers, MRI was significantly more accurate than MDCT (P < 0.05). The weighted kappa values indicate good agreement (kappa = 0.61) between observers for MDCT, and excellent agreement (kappa = 0.82) for MRI. CONCLUSION: Pancreatic MRI shows better diagnostic performance than MDCT for differentiating IPMNs from other cystic lesions of the pancreas.

OBJECTIVE: The purpose of this study was to determine whether fusion imaging-guided percutaneous radiofrequency ablation (RFA) is effective in the management of hepatocellular carcinoma (HCC) that has poor conspicuity at conventional sonography. SUBJECTS AND METHODS: Percutaneous RFA of HCC with poor conspicuity was performed under fusion imaging guidance. The time needed for image fusion between the ultrasound and CT or MR images was recorded. The quality of image fusion and the degree of operator confidence in identifying the index tumor were graded on 4-point scales. Technical success and procedure-related complications were evaluated with liver CT immediately after RFA. RESULTS: Thirty patients with HCC (1.0 ± 0.3 cm) were enrolled. Twenty-seven of the 30 lesions detected at planning ultrasound were identified with fusion imaging. Of the 30 HCC candidate lesions detected with ultrasound, five were found to be pseudolesions close to the index tumor. The time needed for image fusion for the 27 lesions was 3.7 ± 2.1 minutes (range, 1.3-9.0 minutes). The quality of image fusion was graded 3.4 ± 0.6, and the degree of operator confidence in identifying the 30 HCCs, 3.3 ± 0.9. The technical success rate was 90% (27/30) in intention-to-treat analysis and 100% in analysis of actually treated lesions. There were no major RFA-related complications. CONCLUSION: Fusion imaging-guided percutaneous RFA is effective in the management of HCC that has poor ultrasound conspicuity.

OBJECTIVE: The purpose of this study was to evaluate the detection rate of targeted sonography for small (<or= 3 cm) hepatocellular carcinomas (HCCs) primarily discovered by CT or MRI and to assess factors affecting lesion visibility on targeted sonography. SUBJECTS AND METHODS: Between October 2005 and April 2008, targeted sonography for small (<or= 3 cm) HCC was prospectively performed in cirrhotic patients. Targeted sonography was performed by a radiologist with knowledge of the size and location of the HCC. Invisible HCCs were compared with visible HCCs with regard to size, distance from the diaphragm, segmental location, subcapsular location, cause of liver cirrhosis, presence or absence of previous treatment, Child-Pugh class, and serum alpha-fetoprotein by using univariate and multivariate analyses. RESULTS: A total of 93 consecutive patients (65 men and 28 women; mean age, 59 years) with 93 HCCs (mean size +/- SD, 1.8 +/- 0.6 cm) were enrolled in this study. Of those, 73 (78.5%) HCCs were visible on targeted sonography. The detection rate was 36.4% (4/11) for HCC <or= 1.0 cm, 77.6% (38/49) for HCC between 1.1 and 2.0 cm, and 93.9% (31/33) for HCC between 2.1 and 3.0 cm. In both univariate and multivariate analyses, the size of the tumor and distance between the tumor and the diaphragm were statistically significant factors affecting sonographic visibility. CONCLUSION: The overall detection rate for small (<or= 3 cm) HCC on targeted sonography was 78.5%. Small size and subphrenic location of the tumor were two independent predictors of sonographic invisibility.

Benign gallbladder diseases usually present with intraluminal lesions and localized or diffuse wall thickening. Intraluminal lesions of the gallbladder include gallstones, cholesterol polyps, adenomas, or sludge and polypoid type of gallbladder cancer must subsequently be excluded. Polyp size, stalk width, and enhancement intensity on contrast-enhanced ultrasound and degree of diffusion restriction may help differentiate cholesterol polyps and adenomas from gallbladder cancer. Localized gallbladder wall thickening is largely due to segmental or focal gallbladder adenomyomatosis, although infiltrative cancer may present similarly. Identification of Rokitansky-Aschoff sinuses is pivotal in diagnosing adenomyomatosis. The layered pattern, degree of enhancement, and integrity of the wall are imaging clues that help discriminate innocuous thickening from gallbladder cancer. High-resolution ultrasound is especially useful for analyzing the layering of gallbladder wall. A diffusely thickened wall is frequently seen in inflammatory processes of the gallbladder. Nevertheless, it is important to check for coexistent cancer in instances of acute cholecystitis. Ultrasound used alone is limited in evaluating complicated cholecystitis and often requires complementary computed tomography. In chronic cholecystitis, preservation of a two-layered wall and weak wall enhancement are diagnostic clues for excluding malignancy. Magnetic resonance imaging in conjunction with diffusion-weighted imaging helps to differentiate xathogranulomatous cholecystitis from gallbladder cancer by identifying the presence of fat and degree of diffusion restriction. Such distinctions require a familiarity with typical imaging features of various gallbladder diseases and an understanding of the roles that assorted imaging modalities play in gallbladder evaluations.