Multiphasic contrast-enhanced multidetector-row CT of liver: contrast-enhancement theory and practical scan protocol with a combination of fixed injection duration and patients' body-weight-tailored dose of contrast material.

The introduction of multidetector-row CT (MDCT) has provided the abdominal radiologists with dramatic changes for the imaging of the liver. At just present, establishment of new and optimal injection protocol in multiphasic contrast-enhanced MDCT of the liver has been yearned because the difficulty and the importance to optimize the scan timing for each phase imaging have obviously increased because of the extremely rapid scan speed with MDCT scanners. Among technical factors employed in an injection protocol for multiphasic contrast-enhanced MDCT of the liver, to make an injection duration of contrast material fixed is the most important for the precise estimation of the scan timing for each phase imaging. With the fixed injection duration, the peak enhancement time of the aorta, portal vein, and liver constantly appear approximately 10, 20, and 30s after the any fixed injection durations (completion of injection of contrast material), respectively. Moreover, using a combination of the fixed injection duration and patients' body-weight-tailored dose of contrast material, similarity of time-density curves of each organ in shape and pattern can be achieved for individual patient with different body weight. In this issue, we will attempt to determine an ultimately optimal, but practical injection/scan protocol to successfully realize multiphasic contrast-enhanced MDCT of the liver based on the contrast-enhancement theory.