Introduction: 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.Materials and 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 quantified by ROI analysis. Results:Twenty-five 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). Conclusion: 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.
Hepatocellular carcinoma (HCC) is the most common primary liver tumour in the liver, and is associated with portal vein thrombosis in up to 44% of patients in an autopsy series. The European Association for the Study of the Liver (EASL) and American Association for the study of Liver Disease (AASLD) diagnostic guidelines for HCC include both invasive and non-invasive criteria. The non-invasive criteria emphasise the characteristic appearance of HCC at dynamic contrast-enhanced imaging techniques, namely arterial phase hypervascularisation and portal venous/ delayed phase washout. A number of studies have validated these non-invasive imaging criteria.
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