Comparison of contrast media injection rates and volumes for hepatic dynamic incremented computed tomography

Contrast injection techniques now in use for hepatic dynamic incremented computed tomography (DICT) were designed for scanners using slower scan acquisition rates than the currently available 6 to 12 scans/minute. Of 53 patients examined, (1) 19 received a conventional 2-minute injection of 150 or 120 mL of 60% contrast material selected by patient weight; (2) 19 received the same doses within 1 minute; and (3) 15 received 20% lower doses within 1 minute. The faster injection groups 2 and 3 reached peak enhancement sooner (57 and 60 seconds vs. 97 seconds) with similar or higher peak hepatic enhancement (73 and 64 HU vs. 58 HU) and equivalent hepatic enhancement (52 and 48 HU vs. 54 HU) after 150 seconds. Because detecting neoplastic liver lesions often depends on enhancement, 1-minute injections of high doses of contrast material with rapid scan rates may be superior to 2-minute injections. When cost or dose-related toxicity are important, 1-minute injections of 20% lower contrast doses may be considered.