Study On CT And MR Image Analysis, Diagnostic And Pathological Basic Of Intrahepatic Peripheral Cholangiocarcinoma

Background and PurposeThe incidence of intrahepatic peripheral cholangiocarcinoma in intrahepatic malignancies is second after HCC. Intrahepatic peripheral cholangiocarcinoma accounts for 5% to 10% of the intrahepatic primary malignant tumors. As the clinical treatment technology continues to improve, early correct diagnosis of IHCC has attracted the attention of the clinically relevant disciplines. Currently CT and MRI are the most common and effective investigation incorporated for the workup and diagnosis of IHCC. In this study, pathologically confirmed IHPCC cases has been analyzed retrospectively, exploring the performance characteristics of CT, MRI and its pathological basis, to further improve the diagnosis of ICC.Materials and MethodsForty-four cases of intrahepatic peripheral cholangiocarcinoma confirmed by clinical surgery or biopsy between January 2008 and March 2012 were collected. All patients had undergone either enhanced CT scan or enhanced MRI scan, and in some case both. Specific analysis is as follows:Contrast enhanced CT scan was performed using 16-slice spiral CT scan machine. Patients received 80ml of non-ionic contrast agent (Ultravist) through intravenous injection at a rate of 2.0-2.5 ml/s using high-pressure syringe during the arterial and portal venous phases. The arterial phase imaging began 12s after the trigger attenuation threshold (100HU) was reached at the level of the supracoeliac abdominal aorta, and the portal phase scanning began 30s after the arterial phase imaging. In some cases delayed phase imaging were also obtained.Patients underwent MRI on a 1.5 T scanner using the phased array coil as the receiever coil, slice thickness of 6-8 mm, intervals 2mm. For enhanced scan, Gd-DTPA was used as contrast agent and administered at a rate of 2 ml/s through the cubital vein, which was flushed with 20 ml of saline using a power injector.2 image analysis incorporating both CT and MRI scans was done. Direct signs like tumor location, shape, size, density and tumor enhancement patterns were included. Indirect signs included intrahepatic bile duct dilatation around tumor, hepatic lobe atrophy, bile duct stones and lymph node metastasis. The interpreted result was compared with single CT or MRI findings taking pathological diagnosis as standard reference, using SPSS 17.0 statistical package and p<0.05 was considered to be statistically significant.ResultsThe CT image showed hypodense lesions with unclear boundaries between lesion and normal liver tissue. The tumors were irregular, lobulated and few were round or oval in shape.4 cases showed intraductal nodular or cauliflower like soft tissue mass, hypodense with dilatation of bile duct. Most of the lesion showed no enhancement during the arterial phase with mild to moderate rim-enhancement in some cases with some showing mild central enhanced strickenings. Delayed phase showed heterogenous internal reinforcement in some of the cases, majority of them being heterogenous, separated or flaked. The intra-ductal tumor showed early mild to moderate rim enhancement with no delayed enhancement. Other common signs were hepatic lobe atrophy and lymph node metastasis. The metastasis sites in descending order on the number of occurrences were superior mesenteric artery root, around the head of pancreas and para-aortic region.MR scan could show the tumor mass more clearly than CT. The mass was seen as hypointense on T1WI and hyperintense or strongly hyperintense on T2WI. Contrast enhanced T1 wighted MRI in arterial phase showed early moderate to marked peripheral enhancement. The intraductal tumor showed dilatation of the bile duct with enhancing mural nodules. Internal delayed enhancement was seen in the delayed phase. CT and MRI diagnosis and pathological diagnosis coincidence rate was 93.8%, significantly higher than that of single application of CT, MRI, the coincidence rate of 71.9%,81.3%(P< 0.05)ConclusionInterpretation of both CT and MRI findings side by side with characterstic findings is beneficial than any of the individual methods and significantly improves the diagnosis rate of ICC. The early rim-enhancement with internal heterogenous delayed enhancement is a characteristic finding in enhanced scans and is of great value for ICC diagnosis.