Chang Jin Han

Macrocystic Neoplasms of the Pancreas: CT Differentiation of Serous Oligocystic Adenoma from Mucinous Cystadenoma and Intraductal Papillary Mucinous Tumor

OBJECTIVE The purpose of our study was to determine useful CT criteria for differentiating serous oligocystic adenomas of the pancreas from other similarly presenting neoplasms, such as mucinous cystadenoma and intraductal papillary mucinous tumor of the branch duct type. MATERIALS AND METHODS Forty-one patients with histologically confirmed macrocystic neoplasms of the pancreas were enrolled: serous oligocystic adenoma in 10 patients, mucinous cystadenoma in 13, and intraductal papillary mucinous tumor in 18. Location, greatest dimension, shape, presence of mural nodules, presence of wall calcification, and the extent and degree of main pancreatic duct (MPD) dilatation were analyzed with CT. The lesions were categorized into seven groups according to their shapes: multicystic, lobulated contour with and without internal septation, smooth contour with and without internal septation, pleomorphic cystic, and clubbed fingerlike cystic. Comparative studies were performed using Fishers exact test and the Mann-Whitney U test. RESULTS Significant differences in lesion shape were found between serous oligocystic adenoma and the other macrocystic neoplasms (mucinous cystadenoma [p < 0.05], intraductal papillary mucinous tumor [p < 0.05]). Serous oligocystic adenoma had a multicystic or lobulated contour with or without septation, whereas mucinous cystadenoma had a smooth contour with or without septation and intraductal papillary mucinous tumor had either a pleomorphic or a clubbed fingerlike cystic shape. Serous oligocystic adenoma showed proximal MPD dilatation from the lesion, whereas intraductal papillary mucinous tumor showed distal or whole MPD dilatation (p < 0.05). No significant difference was apparent among the three diseases in terms of location, greatest dimension, or presence of calcification or mural nodules. CONCLUSION Serous oligocystic adenoma of the pancreas has characteristic CT findings that differentiate it from other cystic tumors. It appears as a multicystic or lobulated cystic lesion with septation.

Saline-Enhanced Hepatic Radiofrequency Ablation Using a Perfused-Cooled Electrode: Comparison of Dual Probe Bipolar Mode with Monopolar and Single Probe Bipolar Modes

Objective To determine whether saline-enhanced dual probe bipolar radiofrequency ablation (RFA) using perfused-cooled electrodes shows better in-vitro efficiency than monopolar or single probe bipolar RFA in creating larger coagulation necrosis. Materials and Methods RF was applied to excised bovine livers in both bipolar and monopolar modes using a 200W generator (CC-3; Radionics) and the perfused-cooled electrodes for 10 mins. After placing single or double perfused-cooled electrodes in the explanted liver, 30 ablation zones were created at three different regimens: group A; saline-enhanced monopolar RFA, group B; saline-enhanced single probe bipolar RFA, and group C; saline-enhanced dual probe bipolar RFA. During RFA, we measured the tissue temperature at 15mm from the electrode. The dimensions of the ablation zones and changes in the impedance currents and liver temperature during RFA were then compared between the groups. Results The mean current values were higher for monopolar mode (group A) than for the bipolar modes (groups B and C): 1550±25 mA in group A, 764±189 mA in group B and 819±98 mA in group C (p < 0.05). The volume of RF-induced coagulation necrosis was greater in group C than in the other groups: 27.6±2.9 cm3 in group A, 23.7±3.8 cm3 in group B, and 34.2±5.1 cm3 in group C (p < 0.05). However, there was no significant difference between the short-axis diameter of the coagulation necrosis in the three groups: 3.1±0.8 cm, 2.9±1.2 cm and 4.0±1.3 cm in groups A, B and C, respectively (p > 0.05). The temperature at 15 mm from the electrode was higher in group C than in the other groups: 70±18℃ in group A, 59±23℃ in group B and 96±16℃ in group C (p < 0.05). Conclusion Saline-enhanced bipolar RFA using dual perfused-cooled electrodes increases the dimension of the ablation zone more efficiently than monopolar RFA or single probe bipolar RFA.

Enhancement characteristics of cholangiocarcinomas on mutiphasic helical CT: emphasis on morphologic subtypes

PURPOSE The purpose of this study was to characterize the differences in CT enhancement pattern among the morphologic subtypes of cholangiocarcinomas. MATERIALS AND METHODS Unenhanced, hepatic arterial (HAP), and portal venous phase (PVP) CT images of 84 patients with pathologically proven cholangiocarcinoma were retrospectively reviewed. Tumors were of the following types: 27 mass-forming, 39 periductal-infiltrating, and 18 intraductal. The CT attenuation values of tumors were measured at each phase. The tumor enhancement ratio (ER) on HAP and PVP was calculated. RESULTS Each cholangiocarcinoma subtype produced characteristic enhancement relative to liver on HAP and PVP images: mass-forming tumors demonstrated hyperenhancing periphery and hyopenhancing centers; periductal-infiltrating tumors, hyperenhancing; and intraductal tumors, hypoenhancing. The ER of the tumor types was significantly different (P<.001, HAP, PVP): periductal-infiltrating tumors showed the highest ER (2.5; 3.8); the centers of mass-forming tumors, lowest (1.5; 2.2); the peripheries of mass-forming tumors, high (2.1; 3.0); intraductal tumors, low (1.9; 2.6). CONCLUSION Cholangiocarcinoma subtypes tended to exhibit distinct enhancement characteristics. Knowledge of these enhancement patterns may aid diagnosis and surgical planning.

Biliary malignancy: value of arterial, pancreatic, and hepatic phase imaging with multidetector-row computed tomography.

Objective: To assess the diagnostic value of arterial, pancreatic, and hepatic phase imaging with multidetector-row computed tomography of a bile duct malignancy. Methods: Our institutional review board approved this retrospective study and waived the requirement for informed consent. Forty-two patients with surgically proven hilar or extrahepatic cholangiocarcinoma, who underwent preoperative imaging with triple-phasic multidetector-row computed tomography, were included in this study. Images obtained during each phase were reviewed by 2 independent observers who assessed the tumor conspicuity and the biliary extent of the tumor and vascular invasion by the tumor. For quantitative analysis, another radiologist measured the tumor attenuation, the normal liver parenchyma, the aorta, and the main portal vein on each phase image. Results: The degree of tumor conspicuity was higher in the pancreatic and hepatic phases than in the arterial phase (P < 0.01); however, there was no statistical difference in tumor conspicuity between the pancreatic and hepatic phases (P > 0.05). The mean tumor attenuation was greater in the hepatic phase at 114.2 ± 24.6 Hounsfield units versus 72.9 ± 18.3 Hounsfield units in the arterial phase (P < 0.001). The images obtained in the hepatic phases were significantly superior to those obtained in the arterial phase for predicting the tumor involvement into the secondary biliary confluence (P < 0.05). In predicting for the vascular involvement by the tumors, there was no significant difference among the 3 enhancement phases (P > 0.05). Conclusions: Routine acquisition of arterial phase images is not necessary for successful detection and evaluation of the extent of hilar or extrahepatic bile duct carcinoma.

Differentiating focal eosinophilic necrosis of the liver from hepatic metastases using unenhanced and portal venous phase computed tomographic imagings: results of univariate and multivariate statistical analyses.

Objective: To evaluate the usefulness of computed tomographic (CT) predictors on portal venous phase images and a new CT predictor on unenhanced images in differentiating focal eosinophilic necrosis (FEN) from hepatic metastases. Materials and Methods: Computed tomographic findings were analyzed in 20 patients with FEN (n = 84) and 23 patients with hepatic metastases (n = 81). Computed tomographic features were compared using univariate and multivariate analyses to determine significant findings. Results: An irregular shape, a subtle low attenuation, a fuzzy margin, and absences of a contour bulging and a rimlike enhancement on the portal venous phase images and absence of a discernable low attenuation on the unenhanced images were significant variables favoring FEN in univariate analysis. In multivariate analysis, no discernable low attenuation on the unenhanced images and an irregular shape and a subtle low attenuation on the portal venous phase images were the variables independently favoring FEN. Conclusions: Not only portal phase images but also unenhanced images can be helpful to differentiate FEN from hepatic metastases.