Assessment of the pancreatic and intrapancreatic bile ducts using 0.5-mm collimation and multiplanar reformatted images in multislice CT

Our objective was to evaluate the ability of multiplanar reformatted (MPR) images combined with 0.5-mm axial images to depict the pancreatic and intrapancreatic bile ducts and compare the results with those of 0.5-mm axial, 2-mm axial, and 6-mm axial images alone. Seventy-seven patients without obstruction of the main pancreatic ducts (MPD) underwent dual-phase helical scanning of the pancreas using multislice computed tomography (MSCT). The MPR images were generated from 0.5-mm-thick images. Visualization of the pancreatic and intrapancreatic bile ducts and their confluence was graded on a four-point scale by a consensus of two radiologists. The results for 0.5-mm axial images in early-phase CT, 2-mm axial images in early-phase CT, MPR images combined with 0.5-mm axial images in early-phase CT, and 6-mm axial images in late-phase CT were then compared. The relationships of the focal pancreatic lesions with the pancreatic ducts were analyzed. The MPR images combined with 0.5-mm axial images were significantly superior to the other three types of images for the visualization of the pancreatic and intrapancreatic bile ducts and their confluence (p<0.01). The depiction rate of the MPD using MPR images combined with 0.5-mm axial images was 94, 94, 95, and 75%, respectively in the head, neck, body, and tail of the pancreas. Accessory pancreatic ducts, intrapancreatic bile ducts, and duct confluence were depicted in 48, 99, and 92%, respectively. In comparison with evaluation based on axial images alone, the use of MPR images more clearly demonstrated the relationship between the lesions and the pancreatic ducts in 14 of 19 lesions. The MPR images combined with 0.5-mm axial images improve the CT depiction of the pancreatic and intrapancreatic bile ducts in comparison with 0.5-mm axial, 2-mm axial, and 6-mm axial images alone.