Jeong et al. MATERIALS AND METHODS From the medical records between January 1998 and June 2002 26 patients with either positive stool examina- tion (n = 24) or surgery (n = 2) for Clonorchiasis sinensis that underwent abdominal MR imaging were entered into this study. The patients included 16 men and 10 women, with ages ranging from 19 to 76 years old, with a mean of 42 years. Nine patients had undergone ERCP. The reasons for the MR imaging were as follows: evaluation of bile duct dilation detected at ultrasonography, evaluation of liver mass detected at CT or ultrasonography and clarification of undetermined abnormalities at ERCP in 18, 5 and 3 cases, respectively. The clinical symptoms were usually nonspe- cific, with the exception of 5 cases with jaundice. The serum bilirubin levels and serum alkaline phosphatase concentrations of 5 and 7 cases, respectively, were elevated. MR imaging was performed on a 1.5T system (Signa Horizon, GE Medical Systems, Milwaukee, WI) using a phased array torso coil. T1-weighted images were acquired using a conventional spin-echo (TR range/TE range, 400 600/7 15) sequence in 11 patients, and an in-phase gradient-recalled echo (GRE) (TR/TE/flip angle = 120/4.2/ 90 ) sequence, and an opposed phase GRE sequence (TR/TE/flip angle = 120/1.8/90 ) in 15. The GRE images were obtained using fast multiplanar spoiled gradient- recalled acquisition. T2-weighted images were obtained with fast spin-echo (FSE, TR range/effective TE = 3,000 7,000/104) sequences in seven patients, and a single shot fast spin-echo (SSFSE, TR/effective TE = /92) sequence in 19. The imaging matrix number was 256 128 or 192 for FSE and GRE sequences, usually using a rectangular field of view to reduce the number of phase-encoding views. The sampling bandwidth was 64 kHz ( 32 kHz) for the FSE sequence, with section thicknesses of 8 mm and a section gap of 2 mm or less. In 21 patients, MRC was performed in thick slab SSFSE sequence (TR/TE/slice thickness = /800/40 mm) and coronal thin slice SSFSE sequence (TR/TE/slice thickness = /180/4 mm). Thick slab images were obtained in the coronal plane and multiple oblique planes. In 24 patients, echo fast gradient echo 3D images (TR/TE/Flip angle, 7 9/2 3/15 ), with spectral fat saturation, were obtained before and after administration of gadopentetate dimeglumine (Magnevist, Berlex, Wayne, NJ). After acquiring unenhanced images, 0.1 mmol/kg of contrast material was injected intravenously, as a rapid bolus, followed by 10 ml of normal saline flush. The images were obtained at 30 45 sec (arterial phase), 70 90 sec (portal venous phase) and 3 5 min (delayed phase) 26 after the contrast injection. In 19 patients, both multiphasic contrast-enhanced dynamic imaging and MRC were performed. All the MR examinations were reviewed by two abdomi- nal radiologists, with final conclusions reached by means of consensus. Image analyses were performed to identify abnormalities of the intrahepatic and extrahepatic bile ducts and the presence of hepatobiliary malignancy. For abnormalities of the intrahepatic ducts, the ductal dilation, “too many intrahepatic ducts” sign, wall thickening, wall enhancement, ductal stricture and filling defects were assessed. Intrahepatic ductal dilation was diagnosed when the ductal diameter was greater than 3 mm or if the ducts were seen in the peripheral portion of the liver (16, 17). The criteria for intrahepatic bile duct dilation were as follows: mild, dilated, but identified as an individual structure; marked massive dilation (greater than 10 mm), with individual ducts difficult to identify (18). “Too many intrahepatic ducts” sign was defined as diffuse, uniform dilatation of the small intrahepatic bile ducts, tertiary, quaternary or more peripheral ducts on MRC (6, 10). Wall enhancement was assessed subjectively, and was defined as having higher signal intensity than the adjacent hepatic parenchyma on contrast-enhanced, delayed phase imaging. Wall thickening of the intrahepatic bile duct was defined as a wall thickness of 1.5 mm or more, using electronic calipers on a PACS monitor (18). Stricture was defined as a focal caliber change present in any segment. On abnormalities of the extrahepatic bile duct, ductal dilation was considered present when the duct was dilated greater than 8 mm (19). The ducts were considered mildly and markedly dilated when the diameters were 8 10 mm or greater than 11 mm, respectively. Wall thickening was defined as a thickness of 1.5 mm or more (18). Associated hepatobiliary malignancies, such as cholangiocarcinoma and hepatocellular carcinoma, were also evaluated. In nine patients that had undergone ERCP, the abnormal findings of the intrahepatic and extrahepatic bile ducts (ductal dilatation, “too many intrahepatic ducts” sign, stricture, and filling defect) were retrospectively reviewed by the same two radiologists, with no prior knowledge of the patients’ clinical information and MR findings. RESULTS The MR findings of the patients with clonorchiasis are summarized in Table 1. Intrahepatic bile duct abnormali- ties were seen in 23 (89%) of the 26 patients. The most common finding was mild dilation of the intrahepatic bile duct, which was present in 21 (81%) patients. “Too many intrahepatic ducts” sign was found in 16 (62%) of the 26 Korean J Radiol 5(1), March 2004