Study on Sex-specific, Individualized Dose Calculation of Contrast Agent in CT Examinations

A large proportion of radiological CT examinations require the intravenous administration of iodine-containing X-ray contrast medium. According to current guidelines, the amount required for CT examinations in the (portal) venous phase is calculated on the basis of body weight (e.g. 0.2-0.4 g iodine/kg body weight), but a standardized application dose of the contrast agent is often also used.

In earlier studies, the investigators found that the iodine contrast in vessels and organs achieved with a standardized amount of contrast agent differs significantly between women and men. On average, women showed around 10% higher iodine contrast than men of the same height and weight. The investigators attribute these differences to physiological, sex-specific differences in blood volume. For example, the blood volume of a woman 175 cm tall and weighing 75 kg is approx. 400 ml less than that of a man of the same height and weight (approx. 4.6 vs. 5.0 l, calculated according to Nadler). Taking blood volume into account, sex was no longer a significant influencing factor in a retrospective cohort (n=274).

The investigators would now like to investigate these results in a prospective study. For this purpose, two groups of patients with a clinical indication for a contrast-enhanced CT scan in the venous phase will be compared:

1. control group with regular weight-adjusted (n = 200) 2. study group with dosing according to blood volume (n = 200).

The hypothesis is that the application scheme adapted to the blood volume leads to a more homogeneous contrasting of women and men. In order to quantify this effect, the iodine contrast values of both groups will be quantitatively analyzed, taking into account other influencing variables (height, weight).

The investigators hope that this approach will reduce or even eliminate the observed sex-specific differences. This would lead to a sex-equal contrast based on an individualized amount of contrast medium.