Pseudo lesions on CTAP secondary to arterio-portal shunts

Purpose: To clarify the characteristics of the defects on computed tomography (CT) during arterial portography (CTAP) due to arterio-portal shunting (APS). Method and patients: The defects in the hepatic parenchyma on CTAP due to angiography proven APS were characterized according to their configuration, size, sharpness of margins, location of the lesion in the liver, and homogeneity of the lesions. Results: Twenty five patients had non-tumor related APS. The shunts were single on angiography in 15 cases and multiple in 10 cases. The APS were due to liver cirrhosis in 22 patients, and to trauma in the other three. The lesions were irregular in shape in nine cases. wedge shaped in six cases, and round in four cases. In three cases both wedge and round lesions were seen. The margins were sharp in five single defects in five cases. The rest of the lesions were judged to have unsharp margins except for one case in which both clear and unclear lesions were present. In 10 cases, internal enhancement of the lesions were seen on CTAP. The location of the defects were central in five cases, peripheral in nine, and both peripheral and central in eight cases. Conclusion: The parenchymal defects due to APS were typically irregular in shape, with unsharp margins and internal enhancement.