Yee Liang Thian MBBS, FRCR, Presenter: Nothing to Disclose

Choon Hua Thng MBBS, Abstract Co-Author: Nothing to Disclose

Pkh Chow, Abstract Co-Author: Nothing to Disclose

Xie Wanying MBBS, Abstract Co-Author: Nothing to Disclose

Albert Su Chong Low MD, Abstract Co-Author: Nothing to Disclose

Shoen Choon Seng Low MD, Abstract Co-Author: Nothing to Disclose

L. L Ooi, Abstract Co-Author: Nothing to Disclose

Y. F. Chung, Abstract Co-Author: Nothing to Disclose

Jin Wei Kwek, Abstract Co-Author: Nothing to Disclose

The 2005 American Association for Study of Liver Diseases (AASLD) guidelines proposed imaging criteria for noninvasive diagnosis of hepatocellular carcinoma (HCC) in cirrhotic patients based on their enhancement pattern but we have observed a high incidence of atypical enhancement characteristics in HCC associated with portal vein thrombosis. The aim of this study is to study the incidence of and characterize the atypical enhancement features in this subgroup of HCC.

Cases of proven HCC associated with portal vein thrombosis were drawn from a surgical database. Only patients who underwent multiphasic CT imaging were selected for analysis. The arterial, portal venous and delayed phase images were assessed qualitatively and quantitatively (with region of interest [ROI] analysis) for lesion hypervascularity and washout. The background enhancement of the left and right lobes of the liver were also quantified by ROI analysis.

24 lesions in 24 patients were selected for analysis. All patients had arterial, portal venous and delayed phase CT images and 19/24 scans had precontrast scans. 17/24 (71%) patients were hepatitis B/C carriers. Mean lesion diameter was 9.7 (±3.8) cm. Qualitative analysis showed that 10/24 (42%) lesions demonstrated arterial hypervascularity while 16/24 (67%) lesions showed washout. 7/24 (29%) lesions were hypodense on all phases. Quantitative analysis showed that the average absolute lesional enhancement from precontrast to arterial phases was 49 (±17) HU for hypervascular lesions compared to 22 (±16) HU for non-hypervascular lesions (p<0.01). The mean absolute enhancement of the background liver parenchyma in the arterial phase was 13.7 (±7.9) HU for hypervascular lesions compared to 36.2 (±32.2) HU for non-hypervascular lesions (p = 0.03). The average absolute contrast washout was -10.1 (±4.2) HU in lesions with washout compared to -4.0 (±9.2) HU in lesions without washout (p = 0.06).

A large proportion of HCC with portal vein thrombosis lack characteristic arterial hypervascularity, which may be secondary to compensatory increased arterial supply to the background liver. This is a potential pitfall when applying imaging criteria for diagnosis of HCC.

Lack of demonstrable hypervascularity in a high proportion of HCC with portal vein thombosis is an imaging pitfall when applying AASLD criteria for noninvasive diagnosis of HCC.

Thian, Y, Thng, C, Chow, P, Wanying, X, Low, A, Low, S, Ooi, L, Chung, Y, Kwek, J, Atypical Enhancement Pattern of Hepatocellular Carcinoma with Portal Vein Thrombosis on Multiphasic CT.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9002334.html