Does Contrast Dose Based in Lean body Weight Allow Lesser Volumes on High BMI Patients for CT Angiography?

The objective was to evaluate whether contrast dose based on lean body weight (LBW) protocol has the potential to reduce contrast volume in patients with high basal metabolic index (BMI) compared to total body weight (TBW)-based protocols.

The Institutional Review Board approval was obtained for this prospective study. Initially, a pilot study with a sample size of 150 patients was conducted to estimate the average fat fraction in our population. Then, CT angiography (CTA) for the thoracic and abdominal aorta was performed using a 256-multidetector computed tomography scanner in 117 patients who were undergoing screening for aortic aneurysm and vascular assessment of prospective transplant donors. The patients were divided into two groups: A TBW group (n = 60) and LBW group (n = 57). Lean body weight (LBW) was estimated from the patient weight, height, and gender using Hume's equation. The TBW group received 1.2 ml/kg contrast dose and the LBW group received 1.6 ml/kg contrast dose to achieve approximately equal iodine dose in both groups. Differences in the degree of aortic enhancement between the estimated LBW and TBW group were evaluated. In higher BMI patients (>25), the mean aortic enhancement (MAEnh) and the contrast volume delivered between the LBW and TBW group were compared.

Mean aortic enhancement (MAEnh) 422.45 (±74.5) Hounsfield unit (HU) in the TBW group and 432.67 (±69.4) HU in the LBW group showed no statistical difference (P = 0.439). In population with BMI >25, the contrast delivered in LBW protocol patients was significantly less (P = 0.00) compared to TBW protocol patients, with no significant difference in the MAEnh between the groups (P = 0.479).

CTA using a LBW protocol helps to significantly reduce the volume of contrast delivered, especially in patients with BMI >25 compared to TBW protocol, without compromising the aortic enhancement.