Observed Deposition of Gadolinium in Bone Using a New Noninvasive in Vivo Biomedical Device: Results of a Small Pilot Feasibility Study

Purpose: To perform a preliminary evaluation of a noninvasive measurement system to assess gadolinium deposition in bone and to investigate the relationship between the administration of gadolinium-based contrast agents (GBCAs) and gadolinium retention in bone. Materials and Methods: In vivo measurement of gadolinium retention in tibia bones was performed in 11 exposed subjects who previously received GBCAs (six exposed subjects were from a study performed 5 years previously involving injection of GBCAs in healthy volunteers; five exposed subjects had self-reported GBCA exposure), and 11 sex- and age-matched control subjects without a history of GBCA exposure. Each subject underwent one measurement of gadolinium retention in the tibia with x-ray fluorescence in a laboratory at McMaster University. A one-tailed t test was performed to compare gadolinium concentration in the exposed group with that in the control group. The relationship between the dose of GBCA administered and the gadolinium concentration measured in bone was analyzed with linear regression. Results: Gadolinium concentration in bone was significantly higher in exposed subjects (mean, 1.19 mu g Gd/g bone mineral +/- 0.73 [standard deviation]) than in control subjects (mean, -1.06 mu g Gd/g bone mineral +/- 0.71) (P =.01). There was also a positive correlation between the dose of GBCA administered and the gadolinium concentration measured in bone (R-2 = 0.41); gadolinium concentration in bone increased by 0.39 mg Gd/g bone mineral +/- 0.14 per 1 mL of GBCA administered. Gadolinium was detected in bone up to 5 years after one GBCA administration. Conclusion: This x-ray fluorescence system is capable of measuring gadolinium deposition in bone noninvasively in vivo. Gadolinium can be retained in bone after one dose of GBCA in healthy subjects.