[Optimal phase of dynamic CT for detecting hypervascular hepatocellular carcinoma: evaluation of double arterial phases].

Abstract

Purpose: To investigate the appropriate time of arterial phase for the detection of hypervascular hepatocellular carcinoma (HCC).

Materials and methods: Fifty-two hypervascular HCCs of 36 patients were evaluated on double arterial-phase images of the liver. The first and second arterial-phase images were obtained 10 sec after aortic peak enhancement time as determined by test bolus injection. Patients received a low or high concentration of contrast medium, according to their body weight, that was administered intravenously at a rate of 4 mL/sec and injection duration of 23 sec. Three radiologists evaluated the images separately.

Results: Sensitivity in detecting hypervascular HCCs was higher in the first arterial phase than in the second arterial phase (p = 0.039). HCCs were not detected as hypervascular nodules in one of 20 cases during 31 or fewer sec, or in 8 of 19 cases during 48 or more sec after the initiation of contrast medium injection. All nodules were detected as hypervascular lesions between 32 and 47 sec after the initiation of contrast medium injection.

Conclusion: When a single arterial phase is obtained to detect hypervascular HCCs with a 23-sec injection time and an injection rate of 4 mL/sec, a protocol is recommended in which scanning is started at 35 sec and ended within 47 sec after initiating the injection of contrast medium.