Recommended Iodine Dose for Multiphasic Contrast-Enhanced Mutidetector-Row Computed Tomography Imaging of Liver for Assessing Hypervascular Hepatocellular Carcinoma: Multicenter Prospective Study in 77 General Hospitals in Japan

Rationale and Objectives: To determine the recommended iodine dose of contrast material (CM) for hepatic arterial-dominant phase (HAP) and hepatic parenchymal phase (HPP) imaging to assess hypervascular hepatocellular carcinoma (HCC). Materials and Methods: This was a prospective study including 348 patients with hypervascular HCC in 77 hospitals as a postmarketing surveillance to investigate the effects of body weight-tailored dose of CM (300 mgl/mL of iohexol) for hepatic multiphasic contrast-enhanced multidetector-row computed tomography imaging. Informed consent was obtained from all patients who were enrolled. The tumor-to-liver contrast (TLC) of HAP images was assessed qualitatively (QL-TLC) and quantitatively (QT-TLC [HU]; computed tomography [CT] value of tumor-CT value of hepatic parenchyma). Minimal and sufficient QT-TLC were defined as CT values corresponding to the median and 75% of QL-TLC assigned with good, respectively. The recommended iodine dose was estimated by the relationship between iodine dose (mgl/kg) and QT-TLC. Results: There was a good correlation between QL-TLC and QT-TLC. The recommended iodine dose of CM for HAP imaging was considered to be in the range of 567-647 mgl/kg based on minimal (33.7 HU) and sufficient QT-TLC (40.9 HU). Meanwhile, the recommended dose of CM for HPP imaging was 572 mgl/kg as a dose that gives hepatic enhancement more than 50 HU during HPP imaging. Conclusions: The recommended iodine dose of CM for HAP and HPP imaging may be different, being 567-647 mgl/kg and 572 mgl/kg, respectively, in assessing hypervascular HCC.