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

Randomized Controlled Study on Sex-specific, Individualized Dose Calculation of Intravenously Administered Contrast Agent in CT Examinations in Portal Venous Phase to Achieve Equivalent Contrast in Men and Women

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.

Inclusion Criteria:

• Presence of a justifying indication for a CT scan of the thorax and abdomen with application of intravenous contrast medium and a start delay corresponding to the portal venous contrast medium phase
• Ability to give informed consent, as well as written and verbal consent to participate in the study available

Exclusion Criteria:

• Cardiorespiratory instability (as assessed by the attending physician)
• Age <18 years
• Existing or suspected pregnancy
• Known post hepatectomy and/or splenectomy
• Lack of current height (in the same inpatient/outpatient hospital stay) or lack of possibility of height measurement
• Lack of current daily body weight or inability to measure body weight
• Height under 140 cm or over 220 cm
• Body weight under 50 kg or over 120 kg
• Contraindication to iodine-containing contrast medium (Allergy to contrast media containing iodine, Severe renal insufficiency (eGFR < 30 ml/min), Hyperthyroidism)