Liver metastases: early detection based on abnormal contrast material enhancement at dual-phase helical CT.

Abstract

To assess whether contrast material enhancement findings on computed tomographic (CT) scans are useful in determination of the risk for development of hepatic metastases. Dual-phase helical CT scans were obtained in 80 patients with nonhepatic cancer and no hepatic metastases visible at CT. Attenuation was measured on scans obtained at 25 and 40 seconds. Peak liver attenuation was determined in all cases. Unenhanced scans were obtained in 35 patients. The ratio of liver attenuation at 25 and 40 seconds to peak liver attenuation, liver enhancement values at 25 and 40 seconds, and ratio of liver enhancement at 25 and 40 seconds to peak liver enhancement were determined. Liver metastases developed during 18-month follow-up in 22 patients. The 25- and 40-second liver enhancement values and the liver enhancement and attenuation ratios were higher in these patients than in those who did not develop metastases (P < .01). Enhancement values and ratios were more accurate than densitometric measurements for predicting development of metastases. Use of an optimal threshold (0.40 or greater) for the 40-second enhancement ratio resulted in a sensitivity of 75%, specificity of 96%, and overall accuracy of 89%. CT measurements may help in the prediction of risk for subsequent development of hepatic metastases.