Use of Delayed Imaging in Computed Tomographic Arterial Portography to Increase Accuracy in Imaging Hepatic Tumors: A Radiologic/Pathologic Correlation.

Background: Computed tomographic arterial portography (CTAP) has been an invaluable tool in detecting hepatic tumors for staging patients with hepatic malignancies. This technique is more sensitive than conventional computed tomography (CT) and allows for accurate surgical planning. One of the major drawbacks of CTAP has been the high false-positive rate. Delayed imaging after CTAP helps identify perfusion artifacts, increasing specificity. Using pathologic analysis of the resected specimen as the gold standard, the current study compares the sensitivity and specificity of standard CTAP to those that include a delayed-phase (210 to 240 minutes) imaging. Results: In 60 patients subjected to both phases of imaging and surgical resection of their hepatic colorectal metastases, 139 tumors were found at pathology. One hundred seventy lesions were identified on standard CTAP, with 55 being false-positive. Using delayed imaging, 155 lesions were noted, with 40 being false-positive. Thus, the sensitivity of CTAP remained high with the delayed imaging (83% vs 82% in standard CTAP), whereas the accuracy increased to 74% from 68% (p 5 .01). The positive predictive values were similarly increased (74% vs 68%). Conclusion: Delayed imaging can be easily performed during the observation period after CTAP. Although there is increased radiation exposure, the delayed images increase the specificity of CTAP significantly. We therefore feel that such delayed imaging should be included in the standard evaluation of the patient with hepatic tumors undergoing CTAP. [ABSTRACT FROM AUTHOR]