Body size indices to determine iodine mass with contrast-enhanced multi-detector computed tomography of the upper abdomen: does body surface area outperform total body weight or lean body weight?

Abstract

Objective: To compare total body weight (TBW), lean body weight (LBW) and body surface area (BSA) for the adjustment of the iodine dose required for contrast-enhanced multi-detector computed tomography (MDCT) of the aorta and the liver.

Methods: One hundred and three patients undergoing MDCT of the abdomen were randomised into three groups: the TBW group receiving 0.6 g iodine/kg of TBW (n = 33), the LBW group receiving 0.75 g iodine/kg of LBW (n = 35) and the BSA group receiving 22 g iodine/m(2) (n = 35). ∆HU (increases in CT value) per gram of iodine (∆HU/g) and adjusted maximum hepatic enhancement (adjusted MHE; ∆HU/[g iodine/kg]) correlated with three groups using linear regressions.

Results: Correlation coefficients of ∆HU/g were 0.67 (TBW), 0.86 (LBW) and 0.85 (BSA) for the aorta, and 0.74 (TBW), 0.77 (LBW) and 0.84 (BSA) for the liver. Adjusted MHE was constant at 70.2 with LBW and at 2.69 with BSA, but correlated positively with TBW (r = 0.58, P < 0.001).

Conclusion: Iodine load may need to be tailored by LBW or BSA in contrast enhanced MDCT of the abdomen. BSA is a simple and feasible index for the determination of iodine dose in individual patients.

Key points: • Optimisation of enhancement is very important for high quality MDCT. • Iodine dose is best adjusted according to LBW or BSA. • BSA may be adopted because calculation is simple. • Iodine dose of 0.712 g/kg LBW/18.6 g/m (2) BSA gives 50 HU hepatic enhancement.