Gadolinium Retention Estimation Tool

This Excel file provides a tool for estimating gadolinium (Gd) retention in patients based on the time (in months) between MRI gadolinium contrast media (Gd-CM) administration and urine sample collection. Users can input spot urine and Chelate-Evoked Metal Excretion Test (CEMET) urine Gd concentrations in µg/g creatinine along the time lapse after Gd-CM exposure in months. The results are then plotted into norm-regression curves with ±95% confidence intervals (CI) to provide an estimate of the lag-time-specific Gd retention.The regression curves are based on data from 54 patient samples. Spot urine samples were collected in the morning while fasting. Subsequently, a standard intravenous infusion of 600 mg glutathione, 1.9 g Na-Ca-EDTA, and 250 mg DMPS was administered, with CEMET urine collected two hours after infusion initiation. This combination of chelation agents enhances sensitivity and broadens the range of metals captured by CEMET.Na-Ca-EDTA effectively binds and promotes the urinary excretion of gadolinium, making it a viable alternative to Zn-DTPA. The tool generates two distinct regression curves: one for short- to medium-term gadolinium retention (<24 months, in sheet 1) and another for long-term retention (2–10 years, in sheet 2), reflecting different slope trends over time.Sheet 3 includes a Python script that enables users to generate norm diagrams and aggregate patient data. This script can be customized to adjust norm diagrams and 95% CIs for specific research questions or patient subsets, such as those differentiated by renal function, lifetime gadolinium exposure, or specific Gd-CM types or brands.While this tool estimates gadolinium retention in tissues after defined intervals following Gd-CM administration, elevated retention values do not necessarily correlate with clinical symptoms. Patients with typical retention may still exhibit symptoms, while those with elevated retention might remain asymptomatic.Increased sensitivity to gadolinium and related pathologies seems to involve autoimmune mechanisms or predisposing factors, such as decreased metal tolerance or increased pre-exam metal exposure, which are not directly linked to gadolinium concentrations in blood or urine. Therefore, this tool is valuable for estimating individual gadolinium retention after Gd-CM exposure but is not intended to determine toxicity levels.