Small arterial-portal venous shunts: A cause of pseudolesions at hepatic imaging

PURPOSE: To compare hepatic angiographic findings of small arterial-portal venous shunts with those of other imaging modalities, and to determine whether these shunts are related to hepatocellular carcinoma. MATERIALS AND METHODS: At hepatic angiography in 223 patients, small arterial-portal venous shunts not directly related to hepatocellular carcinoma and focal areas of parenchymal contrast material enhancement more than 1 cm in diameter were found in 28 patients. These 28 patients were prospectively evaluated with computed tomography (CT) during arterial portography (CTAP) (n = 12), CT after iodized oil administration (n = 23), intraoperative ultrasonography (n = 5), or follow-up hepatic angiography (n = 13). Magnetic resonance (MR) images (n = 10) and dynamic CT scans (n = 4) in these patients were retrospectively reviewed. RESULTS: Arterial-portal venous shunts noted at angiography manifested as perfusion defects at CTAP in 10 patients and as an area of arterial contrast enhancement at dynamic CT in three patients. No lesion was seen at MR imaging, and no persistent iodized oil uptake was seen at CT. There was no evidence of hepatocellular carcinoma tumor growth around the shunts at follow-up angiography, and no tumor was present at surgery. CONCLUSION: Understanding of the hemodynamic changes caused by these small shunts can aid in the interpretation of vascular imaging findings.