| Objective:To explore the diagnostic value of MSCT versus MRI combined with MRCP for cholangiocarcinoma.Patients and Methods:We retrospectively collected 34 patients with cholangiocarcinoma confirmed by surgery and histopathological exam at our institution from April 2009 to February 2011.These patients were all examined by CT and MRI/MRCP before surgery where 24 patients underwent MSCT and 20 patients MRI/MRCP.10 patients had both MSCT and MRI/MRCP done. Imaging findings from both MSCT and MRI/MRCP are compared to histopathological findings.Results:1) pathological findings of the 34 cases with presurgical diagnosis of cholangiocarcinoma are adenocarcinoma with different degree of differentiation:5 cases with low differentiation,6 cases with moderate differentiation,9 cases well-differentiated,9 cases with moderate-low differentiation,and 5 cases with moderate-high differentiation; 2) In these cases,24 patients who were routinely examined by MSCT and 20 by MRI/MRCP have the following lesion sites:intrahepatic cholangiocarcinoma 4 cases,hilar cholangiocarcinoma 6 patients, extrahepatic bile duct carcinoma 14 cases in MSCT group while in MRI/MRCP group,there are 1 case,6 cases and 13 cases accordingly; 3) lesions forms are:in MSCT group-mass type 9 cases, infiltrating type 14 cases and intraluminal type 1 case; MRCP group they are 8 cases,1 case and 11 cases accordingly; 4) Bile duct dilatation degree classification:MSCT group-mild dilatation 3 cases, moderate dilatation 6 cases and severely dilatation 15 cases; MRI/MRCP group-2 cases,5 cases and 15 cases accordingly.5) MSCT imaging findings of cholangiocarcinoma: intrahepatic type 4 cases where in unenhanced CT scan, there is irregular low density shadow in the liver parenchyma, hazy borders of lesions, with bile duct dilatation proximal to the lesions; the lesions have delayed enhancement during dynamic contrast enhanced scan, Hepatic lobe atrophy 2 cases, gallbladder dilatation 1 case, portal vein invasion 1 case, lymph node metastasis 1 case, intrahepatic biliary calculi 1 case. Hilar cholangiocarcinoma 6 cases, with mass shadow within hilar zone, unenhanced CT findings are either linear, nodular or irregular soft tissue shadow, slightly low density 4 cases, average density 2 cases; On dynamic contrast enhanced scan,6 cases in arterial phase the lesions are enhanced slightly, enhancement average value of lesions is 15Hu; In portal venous phase, enhanced markedly 6 cases and enhancement average value is 35Hu; in delayed phase, enhanced markedly 6 cases and enhancement average value is 40Hu. In other words, the lesions are uneven or marginal enhancing in arterial phase, continuously enhancing in portal venous phase and obvious enhancement in delayed phase, dilated bile ducts are better visualized after MPR and MIP with 3D reconstruction in venous or balanced phases.With cholecystitis 1 case, gallstones 1 case, narrow hepatic artery 1 case, lymph node metastasis 1 case, bile duct severe dilation 5 cases and moderate dilatation 1 case. Extrahepatic bile duct carcinoma 14 cases, occurring in superior and middle part of duct is 1 case each, the rest 12 cases are in the inferior part; the image findings are soft tissue masses with average or low density, where average density is in 12 cases, slightly low density in 2 cases, other CT imaging findings for soft tissue masses shadow are luminal obstruction 2 cases, infiltrating type 6 cases, mass type 6 cases, on contrast enhanced scan, there is no obvious density difference for all soft tissue masses, bile ducts and duodenal wall, thereby displaying no distinct borders; the range of CT density value of cholangiocarcinoma is between 29 and 49 Hu, average is 35 Hu on plain scan, on dynamic enhanced scan, the lesions are significantly enhanced, CT value ranging 15～39 HU on arterial phase,25～40 HU on venous phage,and 35～40 Hu on delayed phase. In all the cases there are bile duct dilatation, gallbladder dilatation, and dilated pancreatic duct only in 1 case.6) MRCP findings of cholangiocarcinoma:Intrahepatic and hilar cholangiocarcinoma types have soft tissue masses, with T1WI isointense signal in 3 cases, slightly low signal 4 cases, T2WI isointense signal 4 cases, slightly high signal 3 cases, the MIP images show filling defect shadow at the roots of bile duct dilatation, with proximal bile duct dilatation and intrahepatic bile duct dilatation like "dentrites", gallbladder dilatation in 2 cases, extrahepatic bile duct carcinoma 13 cases, superior part of duct 1 case, middle part of duct 1 case, the rest 11 cases are at inferior part, the appearance at obstruction site is either cone, beak, or rat tail shape,the signal at site of obstruction is irregular, T1WI low signal 9 cases,isointense signal 4 cases, T2WI low signal 2 cases, high signal 11 cases, distal to the dilatation of bile duct is luminal stenosis, deformation, an irregular stricture in MRCP images, bile duct appears irregularly thickened or completely blocked. In 6 patients, ampullary part of common bile duct carcinoma shows inhomogeneous signal loss at site of obstruction while the proximal common bile duct and main pancreatic duct dilatation show the "double duct" sign, accompanied by intrahepatic bile duct dilatation having "dendritic" appearance, the gallbladder is also enlarged.7) For the 24 routine CT and 20 routine MRI/MRCP examination, the diagnostic accuracy rate for lesion location is both 100%, no difference; For the 24 routine CT and 20 routine MRI/MRCP, diagnostic accuracy rate for lesion characterization is respectively 62.5%,70%, by statistical X2 test (P>0.05),no statistically difference.In the 24 routine CT and 10 routine cases with both CT and MRI/MRCP,the qualitative diagnosis accuracy rate using statistical X2 test (P<0.05), there is difference; in 20 routine MRI/MRCP and 10 routine CT combined with MRI/MRCP,the qualitative diagnosis accuracy rate compared by statistical X2 test (P>0.05), no significant statistically difference; Different reconstruction techniques used in CT (MIP, MPR and CPR) for reconstructing the biliary tree can show the site of obstruction, shapes and density of the lesions clearly.However they are not qualitatively comparable with MRCP, but there is no obvious difference for diagnosis of cholangiocarcinoma.Conclusion:1) Cholangiocarcinoma is mainly adenocarcinoma, extrahepatic location, infiltration type and the degree of bile ducts dilation is different; 2) MSCT and MRCP are able to show characteristics and range of cholangiocarcinoma lesions clearly. MPR and CPR reconstructions from MSCT can show lesions better in different enhancement phases, but it is poor for showing the dilatation of the whole biliary tree compared to MRCP; 3) MSCT and MRCP can diagnose the location of cholangiocarcinoma correctly; The qualitative diagnosis accuracy rate of MSCT and MRCP for cholangiocarcinoma is not same,but there is no significant difference; The qualitative diagnosis accuracy rate of MSCT combined with MRCP for cholangiocarcinoma compared to MSCT only is higher,and there is statistical difference; The qualitative diagnosis accuracy rate of MSCT combined with MRCP for cholangiocarcinoma compared to MRCP is higher,and there is no statistically difference. |
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