• John R Leyendecker, Mandip Gakhal, Khaled M Elsayes, Ronan McDermott, Vamsidhar R Narra, and Jeffrey J Brown.
• Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, MO, USA. jleyende@wfubmc.edu
• J Comput Assist Tomogr. 2008 Mar 1; 32 (2): 178-84.

ObjectiveTo determine the enhancement phase providing the highest contrast-to-noise ratio (CNR) between cholangiocarcinoma and liver or portal vein on dynamic and delayed gadolinium-enhanced magnetic resonance imaging (MRI).Subjects And MethodsPrecontrast, 3-phase dynamic postcontrast, and delayed postcontrast MRI of the liver was performed in 25 patients with cholangiocarcinoma and correlated with surgical findings, pathology, and other imaging studies. Contrast-to-noise ratios for tumor relative to adjacent liver and portal vein were calculated from signal intensities determined from regions of interest obtained for each phase of enhancement. A subjective assessment of the signal intensity of the periportal tissues relative to the portal vein was made for each set of delayed images.ResultsA mass was visible in 24 of 25 patients. Tumor masses were hypointense in 92%, 67%, 75%, and 21%; isointense in 8%, 8%, 17%, and 12%; and hyperintense in 0%, 25%, 8%, and 67% of patients relative to liver on precontrast, arterial, portal venous, and delayed images, respectively. No single phase of gadolinium enhancement demonstrated consistently superior tumor-versus-liver CNR. Delayed imaging demonstrated the highest tumor-versus-liver CNR in 25% of patients and the lowest in 33%. The portal venous phase demonstrated the highest tumor-versus-portal vein CNR in 75% of patients. Delayed postcontrast images demonstrated the lowest tumor-versus-portal vein CNR in 38% of patients. Periportal tissues were isointense to portal vein in all but 1 patient on delayed images.ConclusionNo single phase of dynamic and delayed gadolinium-enhanced MRI demonstrates superior CNR between cholangiocarcinoma and normally enhancing liver, although the portal phase provides the best CNR between tumor and portal vein in most cases. Although delayed enhancement is typical of cholangiocarcinoma, delayed imaging does not necessarily offer superior contrast between tumor and liver parenchyma compared with other phases of enhancement. Differentiation between tumor and portal vein and periportal tissues may be difficult on delayed images.

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