Detection by CT during arterial portography of colorectal cancer metastases to liver. A prospective evaluation of the accuracy of real-time ultrasonography (US), computed tomography (CT), infusion hepatic angiography (IHA), and computed tomography during arterial portography (CT-AP) was performed on 65 resected liver metastases of colorectal cancers. The total detection rate was 58.5 percent for US, 56.3 percent for CT, 55.4 percent for IHA, and 86.2 percent for CT-AP. The sensitivity of 29 lesions with diameters of smaller than 1 cm was 65.5 percent for CT-AP, CT found only two, and both US and IHA localized no more than three. The smallest lesions detectable by CT-AP were as small as 0.4 cm in diameter. CT-AP proved most useful in detecting the liver metastases, and the use of this technique is recommended for preoperative planning of hepatectomy on patients with liver metastases. 