Comparison of Gadolinium Contrast Agent Retention in Patients Receiving Multiple Contrast-enhanced MRI Exams

Gadolinium-based contrast agents have long been utilized in magnetic resonance imaging (MRI) to enhance image quality. Aside from the few reported cases of Nephrogenic Systemic Fibrosis in patients with severely compromised renal function, these contrast agents have generally been viewed as safe. However, recent studies have shown evidence of the retention of potentially toxic gadolinium well beyond the previously recognized clearing times in patients with normal renal function. This retention has been shown via persistent hyper-intense signal in certain brain regions in unenhanced MRI exams. The exact form of retained gadolinium and its long-term potential health effects remain unknown at this time. Due to concerns over retained gadolinium, our hospital switched to a more stably bound contrast agent in the spring of 2018. This study examined brain MRI images from patients with multiple contrast-enhanced exams using either the older, more unstable, linear agent, and the newer, more stable, macrocyclic agent. Signal intensities were measured in the globus pallidus and dentate nucleus; regions of the brain that have previously been shown to accumulate heavy metals such as gadolinium. Statistically significant increases in signal intensity were seen in the dentate nucleus in the linear contrast agent group, but not in the macrocyclic agent group. No significant signal increases were seen with either agent in the globus pallidus region of the brain. No correlation was seen between signal increase and the volume of contrast agent administered for either region or contrast agent.