Are unenhanced scans necessary in biphasic contrast-enhanced helical CT for detection of hepatic tumors?

We evaluated the need for preliminary unenhanced scans in biphasic contrast-enhanced helical CT for detection of hepatic tumors in 228 consecutive patients in this study. All patients had both unenhanced non-contrast (NC) and contrast-enhanced biphasic CT (BPCT) including hepatic arterial phase (HAP) and portal venous phase (PVP) studies with a helical CT scanner. Two hundred ninty-three hepatic tumors were found in 182 patients with the combined readings of NC, HAP and PVP images, but 2 (0.68%) were missed when the NC images were not included in the readings. There was no statistically significant difference in the sensitivities of lesion detection either with or without NC images when reading the BPCT (p＞ 0.99). As a consequence, the necessity of routine unenhanced CT prior to intravenous contrast enhancement is minimized when the clinical questions is the presence or absence of hepatic tumors. The elimination of unenhanced scans from helical BPCT of the liver could help in saving money, increasing patient throughput and reducing patient exposure to radiation.