Techniques for computed tomography of the liver

We recommend that the CT technique of choice for routine screening of the liver, especially when there is potential for neoplasia, is dynamic CT using a single monophasic bolus of not less than 150 mL of a 60% iodinated contrast agent and a dynamic incremental package yielding at least 7 sections/minute. Routine use of noncontrast CT prior to dynamic CT is not indicated unless there is suspicion of a hypervascular tumor. We prefer to examine these particular patients with delayed CT 4 to 6 hours after receiving at least 60 g of iodine, as lesion to liver contrast is superior to noncontrast CT. Other indications for delayed CT include indeterminate lesions on dynamic CT or CTAP and perfusion defects on CTAP. In patients who are possible candidates for hepatic tumor resection, more invasive techniques such as CTAP are indicated as they yield the highest sensitivity to focal hepatic lesions, especially small lesions. A combination of CTAP and MR, however, demonstrates a superior lesion detection rate than either modality alone. CT-Lipiodol is a useful technique for detecting and palliating hepatocellular carcinomas, especially in patients with concomitant cirrhosis.