Gadolinium Retention Estimation Tool

This Excel file provides a tool for estimating Gadolinium (Gd) retention in patients based on the time-lapse (in months) between the administration of MRI Gadolinium Contrast Media (Gd-KM) and urine sample collection. Users can input both spot urine and Chelate-Evoked Metal Excretion Test (CEMET) urine concentrations in µg/g creatinine, which are then aggregated into norm-regression curves with ±95% Confidence Intervals (CI). These curves are based on data from 54 patient samples.Spot urine samples were collected from patients in the morning while fasting. Following this, 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 the start of the infusion. This combination of metal excretion agents was designed to enhance sensitivity and broaden the spectrum of metals captured by the Chelate-Evoked Metal Excretion Test (CEMET). Notably, Na-Ca-EDTA is effective at binding and promoting the urinary excretion of Gadolinium and can be used as an alternative to Zn-DTPA for this purpose.The tool generates two separate regression curves: one for short- to medium-term Gadolinium retention (< 24 months, located in sheet 1) and another for long-term retention (2–10 years, located in sheet 2), as the slopes of the norm curves differed between these time periods. A Python script for generating norm diagrams and aggregating patient data is provided in sheet 3. This script can be used to adapt the norm diagrams and 95% CIs for specific patient subsets, such as those distinguished by renal function, lifetime Gadolinium exposure, or specific Gd-KM types or brands.While this tool is useful for estimating the degree of Gadolinium retention in tissues after defined intervals following Gd-KM administration, it should be noted that elevated Gadolinium retention values do not necessarily correlate with symptoms. Some patients with typical retention values may still exhibit symptoms, and patients with elevated retention may not experience symptoms. Increased sensitivity to Gadolinium and associated pathology appear to involve autoimmune mechanisms or predisposing factors, such as decreased metal tolerance and increased pre-exam metal exposure, which are not directly correlated with Gadolinium concentrations in blood. Thus, this tool is particularly valuable for estimating individual Gadolinium retention after exposure to Gd-KM, but it is not intended to determine toxicity levels.