Background: Gadolinium-based contrast agents (GBCAs) are widely used in MRI, despite safety concerns regarding deposition in brain and other organs. In animal studies gadolinium was detected for weeks after administration in the kidneys, but this has not yet been demonstrated in humans.
Purpose: To find evidence for the prolonged presence of gadobutrol in the kidneys in healthy volunteers.
Study type: Combined retrospective and prospective analysis of a repeatability study.
Population: Twenty-three healthy volunteers with normal renal function (12 women, age range 40-76 years), of whom 21 were used for analysis.
Field strength/sequence: Inversion recovery-based T1 map at 3T.
Assessment: T1 maps were obtained twice with a median interval of 7 (range: 4-16) days. The T1 difference (ΔT1 ) between both scans was compared between the gadolinium group (n = 16, 0.05 mmol/kg gadobutrol administered after T1 mapping during both scan sessions) and the control group (n = 5, no gadobutrol). T1 maps were analyzed separately for cortex and medulla.
Statistical tests: Mann-Whitney U-tests to detect differences in ΔT1 between groups and linear regression to relate time between scans and estimated glomerular filtration rate (eGFR) to ΔT1 .
Results: ΔT1 differed significantly between the gadolinium and control group: median ΔT1 cortex -98 vs. 7 msec (P < 0.001) and medulla -68 msec vs. 19 msec (P = 0.001), respectively. The bias corresponds to renal gadobutrol concentrations of 8 nmol/g tissue (cortex) and 4 nmol/g tissue (medulla), ie, ~2.4 μmol for both kidneys (0.05% of original dose). ΔT1 correlated in the gadolinium group with duration between acquisitions for both cortex (regression coefficient (β) 16.5 msec/day, R2 0.50, P < 0.001) and medulla (β 11.5 msec/day, R2 0.32, P < 0.001). Medullary ΔT1 correlated with eGFR (β 1.13 msec/(ml/min) R2 0.25, P = 0.008).
Data conclusion: We found evidence of delayed renal gadobutrol excretion after a single contrast agent administration in subjects with normal renal function. Even within this healthy population, elimination delay increased with decreasing kidney function.
Full Access Link: Journal of Magnetic Resonance Imaging