CONTRAST-ENHANCED SPIRAL CT OF THE LIVER - EFFECT OF INJECTION TIME ON TIME TO PEAK HEPATIC ENHANCEMENT

Purpose: On contrast-enhanced hepatic CT, maximum tumor detection of l iver metastases from colorectal cancer is achieved at peak hepatic enh ancement. We investigated the relationship between injection time of c ontrast medium and time to peak hepatic enhancement (TPHE) after the e nd of injection. Method: One hundred nineteen patients without a cardi ovascular disorder were enrolled in this study. Before the spiral CT w as performed, a small amount of contrast medium was injected and a sin gle level dynamic CT was performed to evaluate aortic enhancement and to determine the scan start time of the spiral examination. Patients w ere divided into three groups; contrast medium was injected over 30 s in 40 patients (Group A), 45 s in 39 patients (Group B), and 60 s in 4 0 patients (Group C). The TPHE after the end of injection was measured , and the difference among the groups was compared using one-way analy sis of variance. A p value of <0.05 was considered a statistically sig nificant difference. Results: The TPHEs of the groups were 25.3 +/- 4. 6 s (Group A), 27.0 +/- 5.8 s (Group B), and 24.4 +/- 4.6 s (Group C) and were similar in value. No statistically significant difference was observed (p = 0.067). Conclusion: Hepatic enhancement reaches its pea k at similar to 25 s after the end of contrast medium injection irresp ective of injection time.