Multiphase contrast-enhanced helical CT of liver metastases from renal cell carcinoma

The aim of this study was to evaluate whether in patients with metastatic renal cell carcinoma (RCC) multiphase liver studies would improve detection of metastatic liver disease. Forty-six consecutive patients with known metastatic RCC underwent standardized non-contrast and triphasic contrast enhanced hepatic CT examinations as part of their routine imaging studies. Once a liver abnormality was detected, it was characterized as metastatic by a panel of three radiologists who followed pre-set criteria. These criteria included change in size, biopsy results and lack of benign features. Presence and conspicuity of liver metastases were graded using a five-point scale by consensus of a panel of three radiologists. The highest number of lesions evaluated per patient was limited to ten. Seventy-two liver metastases were detected in 16 patients. Of these, 54 were seen on unenhanced scans; 47 in the hepatic arterial (HA) phase, at 25 s; 65 in the portal-venous (PV) phase, at 60 s; and 49 in delayed images, at 90 s. Scanning only during the PV phase would have missed seven lesions (10%), six of which were seen on unenhanced images and six were seen in HA phase. All patients with metastatic liver disease would have been identified by combination of unenhanced and PV phase or by HA and PV phase scanning. Forty-two lesions were graded more conspicuous on the PV phase, whereas 18 (25%) were more conspicuous on the HA phase. The combination of unenhanced, HA and PV scanning should be considered in the initial evaluation of patients with metastatic RCC for improved lesion detection and characterization. Subsequently, the combination of unenhanced and PV phase imaging is preferred.