Hepatic enhancement differences when dosing iodinated contrast media according to total versus lean body weight

Background: Recent studies suggest potentially improved inter-patient variability in hepatic enhancement by dosing contrast media (CM) according to lean body weight (LBW); however, studies vary in dosing strategy and most involved solely Japanese patients. Purpose: To compare the magnitude and inter-patient variability in mean hepatic enhancement (MHE) when dosing CM according to total body weight (TBW) versus LBW in a Western population. Material and Methods: With ethics approval, this study comprised two parts: (i) 100 CTs acquired with 1.3 mL Isovue 370/kg TBW were analyzed; (ii) 108 patients were consented for LBW dosing at 1.9 mL/kg (max. 150 mL, both groups). Liver attenuations were obtained from regions of interest. The MHE, MHE per gram of iodine (MHE/I), and adjusted MHE (aMHE = MHE/(I/TBW or LBW)) were calculated. We compared patient populations (Fisher’s exact test, t-tests) and inter-patient variability (F-tests of variances in MHE) and performed linear regressions of MHE and aMHE. Results: Cohorts were similar in age, sex, TBW, LBW, and total CM dose. MHE was higher in part 2 (63.1 ± 13 vs. 56.3 ± 12 HU, P = 0.0001) but variances were similar (P > 0.7). In part 2, men received more CM (P = 0.0002) and MHE was higher (P = 0.0002); women received less CM (P = 0.053) but showed a non-significant trend for greater MHE (P = 0.07). MHE/I was higher for women in part 2 (P = 0.01) and stable in men (P = 0.72). Linear regressions showed no lines of best-fit with non-zero slopes, for both sexes and study parts. Conclusion: With CM dose constant, LBW dosing yielded a higher magnitude in MHE but did not reduce inter-patient variability.