CT DURING ARTERIAL PORTOGRAPHY FOR THE PREOPERATIVE EVALUATION OF HEPATIC-TUMORS - HOW, WHEN, AND WHY

CT during arterial portography (CTAP) is the most sensitive technique for the detection of intrahepatic tumors. CTAP is based on portal enha ncement of the liver by infusion of contrast material through the supe rior mesenteric artery. This technique provides clear delineation of i ntrahepatic vessels, allowing segmental location of tumors to be accur ately determined and relationships between tumors and intrahepatic ves sels to be assessed. CTAP must be limited to patients for whom noninva sive preoperative imaging examinations have shown a potential for hepa tic resection. In the majority of the cases, CTAP is performed in pati ents with hepatic metastases from colorectal cancer, but other types o f tumor (either primary or secondary) may be an indication for CTAP. V isualization of nontumorous perfusion defects is a limitation of this technique, but such defects have been well described and have characte ristic locations and appearance. In difficult cases, correlation with sonographic, CT, and MR imaging findings helps characterize portal per fusion defects. CTAP data can be viewed as multiplanar and three-dimen sional reconstructions that allow preoperative planning of the extent of resection and determination of the volume of the remaining liver. T he use of spiral CT shows promise in the performance of CTAP.