Long-Term Evaluation of Gadolinium Retention in Rat Brain After Single Injection of a Clinically Relevant Dose of Gadolinium-Based Contrast Agents

Abstract

The aim of this study was to investigate the presence and chemical forms of residual gadolinium (Gd) in rat brain after a single dose of Gd-based contrast agent. Methods: Four groups of healthy rats (2 sacrifice time-points, n = 10/group, 80 rats in total) were randomized to receive a single intravenous injection of 1 of the 3 Gd-based contrast agents (GBCAs) (gadoterate meglumine, gadobenate dimeglumine, or gadodiamide) or the same volume of 0.9% saline solution. The injected concentration was 0.6 mmol/kg, corresponding to a concentration of 0.1 mmol/kg in humans after body surface normalization between rats and humans (according to the US Food and Drug Administration recommendations). Animals were sacrificed at 2 washout times: 1 (M1) and 5 (M5) months after the injection. Total Gd concentrations were determined in cerebellum by inductively coupled plasma mass spectrometry. Gadolinium speciation was analyzed by size-exclusion chromatography coupled to inductively coupled plasma mass spectrometry after extraction from cerebellum. Results: A single injection of a clinically relevant dose of GBCA resulted in the detectable presence of Gd in the cerebellum 1 and 5 months after injection. The cerebellar total Gd concentrations after administration of the least stable GBCA (gadodiamide) were significantly higher at both time-points (M1: 0.280 ± 0.060 nmol/g; M5: 0.193 ± 0.023 nmol/g) than those observed for macrocyclic gadoterate (M1: 0.019 ± 0.004 nmol/g, M5: 0.004 ± 0.002 nmol/g; P < 0.0001). Gadolinium concentrations after injection of gadobenate were significantly lower at both time-points (M1: 0.093 ± 0.020 nmol/g; M5: 0.067 ± 0.013 nmol/g; P < 0.05) than the Gd concentration measured after injection of gadodiamide. At the 5-month time-point, the Gd concentration in the gadoterate group was also significantly lower than the Gd concentration in the gadobenate group (P < 0.05). Gadolinium speciation analysis of the watersoluble fraction showed that, after injection of the macrocyclic gadoterate, Gd was still detected only in its intact, chelated form 5 months after injection. In contrast, after a single dose of linear GBCAs (gadobenate and gadodiamide), 2 different forms were detected: intact GBCA and Gd bound to soluble macromolecules (above 80 kDa). Elimination of the intact GBCA form was also observed between the first and fifth month, whereas the amount of Gd present in the macromolecular fraction remained constant 5 months after injection. Conclusions: A single injection of a clinically relevant dose of GBCA is sufficient to investigate long-term Gd retention in the cerebellar parenchyma. Administration of linear GBCAs (gadodiamide and gadobenate) resulted in higher residual Gd concentrations than administration of the macrocyclic gadoterate. Speciation analysis of the water-soluble fraction of cerebellum confirmed washout of intact GBCA over time. The quantity of Gd bound to macromolecules, observed only with linear GBCAs, remained constant 5 months after injection and is likely to represent a permanent depo...

Retention of Gadolinium in Brain Parenchyma: Pathways for Speciation, Access, and Distribution. A Critical Review

“…Interestingly, even a single administration of a clinically‐relevant dose of GBCA demonstrated that linear GBCAs resulted in significantly higher residual Gd concentrations in the cerebellar tissue than a macrocyclic GBCA at the late timepoint of 5 months. Furthermore, for the linear GBCAs, two classes of Gd species were detected: intact Gd chelate and Gd bound to soluble macromolecules (>80 kDa), whereas, in the case of the macrocyclic GBCA, Gd was detected only in its chelated form 49 . The nature of the macromolecules that bind Gd remains unknown.…”

“…Gd speciation in the brain has been the subject of a large number of studies. 24,25,[46][47][48][49] In homogenates of cerebellum from rats treated with linear agents, the presence of soluble macromolecular (250-300-kDa) Gd-containing species was observed 24 days after the last administration, while no such effect was found with macrocyclic GBCAs. Still, in linear GBCAs-treated rats, Gd was found to a large extent in the insoluble brain tissue fraction.…”

Role of gadolinium-based contrast agents in neurological disorders

“…Furthermore, gadolinium compounds can deposit not only in deep grey matter but also in the cerebral cortex. Even one single-use dosage of a GBCA can lead to long-term gadolinium accumulation [41,42].…”

“…Linear GBCAs probably undergo partial dechelation and a large portion of gadolinium is retained in the brain, with binding of soluble gadolinium to macromolecules, making clearance potentially impossible. On the other hand, macrocyclic compounds are retained as original chelates and are eliminated over time [42,48,49].…”

Detection of U-87 Tumor Cells by RGD-Functionalized/Gd-Containing Giant Unilamellar Vesicles in Magnetization Transfer Contrast Magnetic Resonance Images

“…brain, kidney, liver, muscles, etc.). [9][10][11][12][13][14] One of the most important goals, that of early diagnosis, can therefore be achieved by developing GBCAs that can specifically accumulate at the pathological tissue, via binding to epitopes that identify the tumor cells, even when the disease is at the preliminary stages. This can reduce the dose of GBCAs and improve the diagnostic potential of MRI.…”