Traces of Gadolinium Found in Brain in Normal Brain Tissue Years Later

Traces of gadolinium used during MR imaging may remain in brain tissue that has no underlying pathology years after the examination, according to a study published in Radiology.

Researchers from the Mayo Clinic in Rochester, MN, sought to determine if gadolinium deposits that have been noted in patients with intracranial abnormalities may also be present in patients with normal brain tissue. “It’s estimated that approximately 400 million doses of gadolinium have been administered since 1988,” study lead researcher, Robert J. McDonald, MD, PhD, staff neuroradiologist at the Mayo Clinic, said in a release. “Gadolinium contrast material is used in 40 to 50 percent of MRI scans performed today.”

To perform their study, the researchers used postmortem neuronal tissues obtained from five patients who had undergone four to 18 gadolinium-enhanced MR examinations with gadodiamide between 2005 and 2014 (contrast group) and samples from 10 gadolinium-naive patients who had undergone at least one similar MR examination during their lifetime (control group).

“By late 2014, the first evidence emerged that gadolinium was depositing within brain tissues. However, many of these patients had underlying medical conditions, such as brain tumors, that could adversely affect the blood brain barrier,” McDonald said in the release. “We were curious if this deposition might be related to the integrity of the blood brain barrier, so we studied patients with normal brain pathology and presumably an intact blood brain barrier.”

Using transmission electron microscopy, mass spectroscopy, and X-ray spectroscopy, the analysis revealed dose-dependent gadolinium deposits in four neuroanatomical regions of the brain in patients who underwent contrast-enhanced MRI. The researchers found that tissues from the four neuroanatomic regions of gadodiamide-exposed patients contained 0.1 to 19.4 mg of gadolinium per gram of tissue in a statistically significant dose-dependent relationship. In contradistinction, patients in the control group had undetectable levels of gadolinium with ICP-MS. All patients had normal brain pathologic characteristics at autopsy. Three patients in the contrast group had borderline renal function (estimated glomerular filtration rate of less than 45 mL/ min/1.73 m²) and hepatobiliary dysfunction at MR examination. Gadolinium deposition in the contrast group was localized to the capillary endothelium and neuronal interstitium and, in two cases, within the nucleus of the cell.

“Our results suggest current thinking with regard to the permeability of the blood brain barrier is greatly oversimplified, as gadolinium appears to accumulate even among patients with normal brain tissue and no history of intracranial pathology.” McDonald concluded. “It will take additional research to understand how and why this deposition is occurring.”[[{"type":"media","view_mode":"media_crop","fid":"61234","attributes":{"alt":"","class":"media-image","id":"media_crop_9631018166722","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"7744","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"height: 249px; width: 800px;","title":"Graphs show gadolinium detection with mass spectrometry of cadaveric tissues. A–D, Changes in gadolinium ion signal intensity detected with mass spectrometry plotted against cumulative intravenous gadolinium exposure for each neuroanatomic area. Strength of association between gadolinium ion signal intensity and dose is shown with Spearman rank correlation coefficient (r) and associated P value. Image provided courtesy of Radiology. ©RSNA 2017.","typeof":"foaf:Image"}}]]