Atypical enhancement pattern of hepatocellular carcinoma with portal vein thrombosis on multiphasic CT.
BACKGROUND
The 2005 American Association for Study of Liver Diseases (AASLD) diagnostic criteria allow non-invasive diagnosis of hepatocellular carcinoma (HCC) based on their enhancement pattern but we have observed a high incidence of atypical enhancement characteristics in HCC associated with portal vein thrombosis. This study seeks to examine the radiological features of this particular subgroup.


METHODS
Patients with HCC and portal vein thrombosis who underwent pre-treatment multiphasic CT imaging were drawn from a surgical database. 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 was also quantifi ed by ROI analysis.


RESULTS
Twenty-fi ve lesions in 25 patients were selected for analysis. Qualitative analysis showed that 10/25 (40%) lesions demonstrated arterial hypervascularity while 16/25 (64%) lesions showed washout. Ten out of 25 (40%) lesions demonstrated both arterial hypervascularity and washout. Quantitative analysis showed that the average absolute lesion enhancement from precontrast to arterial phases was 49.1 (± 17.1) HU for hypervascular lesions compared to 23.8 (± 16.6) HU for non-hypervascular lesions (P <0.01). The mean absolute enhancement of the background liver parenchyma in the arterial phase was 13.79 (± 7.9) HU for hypervascular lesions compared to 36.6 (± 30.6) HU for non-hypervascular lesions (P = 0.03).


CONCLUSIONS
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.
Department of Diagnostic Radiology, Tan Tock Seng Hospital, Singapore. ylthian@gmail.com
Yee Liang
YL
Thian
Albert S C
AS
Low
Pierce K H
PK
Chow
London L
LL
Ooi
Alexander Y F
AY
Chung
Shoen C S
SC
Low
Wanying
W
Xie
Choon Hua
CH
Thng
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006528:Carcinoma, Hepatocellular / Q000150:complications / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000150:complications / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D010363:Pattern Recognition, Automated; D011169:Portal Vein / Q000000981:diagnostic imaging / Q000503:physiopathology; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D020246:Venous Thrombosis / Q000000981:diagnostic imaging* / Q000209:etiology