Optimal injection rate and volume of contrast medium for observing hemodynamics of a hepatocellular carcinoma...

This study aimed to identify the optimal concentration, injection rate, and total volume of contrast medium (CM) for evaluating the hemodynamics of a hepatocellular carcinoma (HCC) structure model of diameter 35 mm, using multi-level dynamic computed tomography (M-LDCT) with 64 detector rows. A tube was inserted in the model as a simulated vessel. Five CM concentrations were used: non-diluted, 2-, 3-, 6-, and 9-fold diluted. Five regions of interest were placed within the HCC structure model. Time-density curves were created for CM injection rates of 1, 2, and 3 ml/s for 10 s, and for a total volume of 10 ml, followed by saline injection at 1 ml/s. M-LDCT maximum intensity projection images were evaluated by four appraisers using a three-point scale (excellent, 2; good, 1; poor, 0). There was no significant difference between maximum CT values at 2 ml/s for 10 s and those at 3 ml/s; these values were both greater than those at 1 ml/s. The duration of the peak was maintained for longer at 3 ml/s for 10 s (5.2 ± 2.3 s) than at 2 ml/s (3.6 ± 0.9 s). Maximum CT values at 2 ml/s of a total volume of 10 ml were greater than those at 3 ml/s. The highest scores of 7 and 8 were found at 2 and 3 ml/s for 10 s, using 2-, 3-, or 6-fold diluted CM. The most appropriate CM rate for evaluating hemodynamics was 2 ml/s for 10 s, using 2-, 3-, or 6-fold diluted CM.