Purpose: Gadolinium-based Contrast Agents (GBCAs) have been used in MRI for a long time. Gd is cleared from the body via glomerular filtration within hours. However, latest researches indicated that Gd could accumulate in organs such as brain and bone as a long-term deposit. A non-invasive technique to measure retained Gd in the body would allow investigation of the potential negative health effects. Gd retention was only thought to be a concern for those with impaired renal function. Nevertheless, new studies have been pointing to the retention of Gd in the brain of individuals with healthy renal function, raises new questions and concerns regarding the safety of the widely used GBCAs.
Methods: In a small animal study, Gd concentration in the brain was measured by a 7T animal MRI at different time intervals after contrast injection (1 hour, 24 hours & 7 days). The mice bones were extracted and Gd deposit was assessed by the 109Cd γ-ray induced K-XRF system. The correlation between Gd concentration in bone and brain will be investigated.
Results: The minimum detection limit of Gd in a bare bone phantom using K-XRF was calculated based on µg Gd per gram phantom and found to be 0.8 ppm. The average brain Gd concentration using MRI relaxivity (R1) mode was measured to be 0.00022 Mol/L for left and right caudoputamen, an hour post-contrast injection. The Gd concentration of 24hour and 7day postcontrast injection for both regions of interest was 0.00021 Mol/L, indicating no substantial reduction of Gd retention in brain.
Conclusion: MRI and XRF systems can be used to quantify Gd retention in the brain and bone. There was no significant decrease of Gd deposit in brain at different time intervals post-contrast injection. Accurate assessment of Gd deposit is crucial for investigating potential toxicity.
Not Applicable / None Entered.