Chelation of gadolinium with deferoxamine in a patient with nephrogenic systemic fibrosis

Gadolinium in Medical Imaging-Usefulness, Toxic Reactions and Possible Countermeasures-A Review

Gadolinium (Gd) is one of the rare-earth elements. The properties of its trivalent cation (Gd3+) make it suitable to serve as the central ion in chelates administered intravenously to patients as a contrast agent in magnetic resonance imaging. Such Gd-chelates have been used for more than thirty years. During the past decades, knowledge has increased about potential harmful effects of Gd-chelates in patients with severe renal dysfunction. In such patients, there is a risk for a potentially disabling and lethal disease, nephrogenic systemic fibrosis. Restricting the use of Gd-chelates in persons with severely impaired renal function has decreased the occurrence of this toxic effect in the last decade. There has also been an increasing awareness of Gd-retention in the body, even in patients without renal dysfunction. The cumulative number of doses given, and the chemical structure of the chelate given, are factors of importance for retention in tissues. This review describes the chemical properties of Gd and its medically used chelates, as well as its toxicity and potential side effects related to injection of Gd-chelates.

Changes in tissue gadolinium biodistribution measured in an animal model exposed to four chelating agents

PURPOSE

This study investigated the potential to reduce gadolinium levels in rodents after repetitive IV Gadodiamide administration using several chelating agents.

MATERIALS AND METHODS

The following six groups of rats were studied. Group 1: Control; Group 2: Gadodiamide only; Group 3: Meso-2,3-Dimercaptosuccinic acid (DMSA) + Gadodiamide; Group 4: N-Acetyl-L-cysteine (NAC) + Gadodiamide; Group 5: Coriandrum sativum extract + Gadodiamide; and Group 6: Deferoxamine + Gadodiamide. Brain, kidney, and blood samples were evaluated via inductively coupled plasma mass spectrometry. The brain was also evaluated histologically.

RESULTS

Kidney gadolinium levels in Groups 4 and 5 were approximately double that of Group 2 (p = 0.033 for each). There was almost no calcification in rat hippocampus for Group 4 rodents when compared with Groups 2, 3, 5 and 6.

CONCLUSION

Our preliminary study shows that excretion to the kidney has a higher propensity in NAC and Coriandrum sativum groups. It may be possible to change the distribution of gadolinium by administrating several agents. NAC may lower Gadodiamide-induced mineralization in rat hippocampus.

Removal of a gadolinium based contrast agent by a novel sorbent hemoperfusion in a chronic kidney disease (CKD) rodent model

Gadolinium based contrast agents (GBCAs) have been linked to toxicity in patients, regardless of having impaired or normal renal function. Currently, no therapy is considered highly effective for removing gadolinium (Gd) from the body. We propose a new strategy to reduce blood Gd content that facilitates whole body removal of Gd using a hemoperfusion system consisting of a cartridge of porous silica beads (Davisil®) functionalized with 1,2-hydroxypyridinone (1,2-HOPO). Herein, we report optimization of the hemoperfusion system using an ex vivo blood and an in vivo rat model of chronic kidney disease (CKD). In our ex vivo system, 1,2-HOPO-Davisil outperformed Gambro activated charcoal (AC), which is commonly used in clinical hemoperfusion of aqueous toxins, in terms of Gd capture capacity and rate. In the CKD rat model, the 1,2-HOPO-Davisil hemoperfusion system removed Gd by 3.4 times over the Gambro AC system. 1,2-HOPO-Davisil did not change complete blood counts and common blood biochemistry. Thus, this strategy has great potential for clinical translation to manage GBCAs after magnetic resonance imaging (MRI), before Gd can deposit in the body and cause long-term toxicity. Although gadodiamide was used as a proof of concept model for GBCAs in this study, 1,2-HOPO functionalized mesoporous silica could also capture dissociated Gd and other GBCAs.

Urinary Gadolinium Levels After Contrast-Enhanced MRI in Individuals with Normal Renal Function: a Pilot Study

INTRODUCTION

Gadolinium-based contrast agents (GBCA) have been used to enhance magnetic resonance imaging (MRI) since 1985. Recently, the media and online groups have voiced concerns about gadolinium deposition in patients with normal renal function based on "elevated" urinary gadolinium levels. The determination of increased urinary gadolinium levels is based on reference ranges developed in individuals with normal renal function who were never exposed to GBCA. Studies suggest an elevated gadolinium urinary elimination greater than 72 h post GBCA scan. We evaluated urine gadolinium concentrations over a 30-day period in patients administered GBCA.

METHODS

In this prospective, observational pilot study, we enrolled subjects between 18 and 65 years of age with normal renal function who received GBCA for the first time. Urinary gadolinium was measured at days zero (prior to GBCA exposure), 3, 10, and 30 after GBCA exposure. We compared urinary gadolinium levels after GBCA exposure to the current reference range and calculated an estimated duration of "elevated" gadolinium urine levels in the average patient.

RESULTS

All 13 subjects had 24-h urinary gadolinium levels higher than 0.7 μg/24 h with means of 1944 (± 1432) μg/24 h on day 3, 301 (± 218) μg/24 h on day 10, and 34 (± 33) μg/24 h on day 30. Based on calculated urinary gadolinium elimination kinetics, we estimate urinary gadolinium levels will often remain above the current reference range for > 50 days.

CONCLUSION

The current reference range of 0.7 μg/24 h for 24 h urinary gadolinium is not applicable to patients for at least 30 days following GBCA exposure.

Evaluating the Patient with Reported Gadolinium-Associated Illness

INTRODUCTION

Gadolinium-based contrast agents (GBCAs) have been increasingly used in clinical practice since their introduction in the 1980s. Recently, increased public attention has been given to patients who report new symptoms following GBCA exposure. This review details the current knowledge surrounding GBCAs, with a focus on the known and proposed disease states that may be associated with GBCAs. Recommendations for the appropriate clinical workup of a patient suspected of having symptoms attributable to gadolinium exposure are included.

DISCUSSION

GBCAs are known to precipitate the disease state nephrogenic systemic fibrosis (NSF), a syndrome characterized by skin thickening in patients with preexisting renal disease. An additional syndrome, termed gadolinium deposition disease, has been proposed to describe patients with normal renal function who develop an array of symptoms following GBCA exposure. While there is a potential physiologic basis for the development of this condition, there is no conclusive evidence to support a causal relationship between GBCA administration and the reported symptoms yet. Clinical evaluation revolves around focused history-taking and physical examination, given the absence of a reliable link between patient symptoms and measured gadolinium levels. There are no recommended treatments for suspected gadolinium deposition disease. Chelation therapy, which is not approved for this indication, carries undue risk without documented efficacy.

CONCLUSIONS

The extent to which GBCAs contribute to clinically relevant adverse effects remains an important and evolving field of study. NSF remains the only proven disease state associated with GBCA exposure. Additional data are required to evaluate whether other symptoms should be attributed to GBCAs.

Gadolinium-based contrast agent toxicity: a review of known and proposed mechanisms

Gadolinium chelates are widely used as contrast media for magnetic resonance imaging. The approved gadolinium-based contrast agents (GBCAs) have historically been considered safe and well tolerated when used at recommended dosing levels. However, for nearly a decade, an association between GBCA administration and the development of nephrogenic systemic fibrosis (NSF) has been recognized in patients with severe renal impairment. This has led to modifications in clinical practices aimed at reducing the potential and incidence of NSF development. Newer reports have emerged regarding the accumulation of gadolinium in various tissues of patients who do not have renal impairment, including bone, brain, and kidneys. Despite the observations of gadolinium accumulation in tissues regardless of renal function, very limited clinical data regarding the potential for and mechanisms of toxicity is available. This significant gap in knowledge warrants retrospective cohort study efforts, as well as prospective studies that involve gadolinium ion (Gd(3+)) testing in patients exposed to GBCA. This review examines the potential biochemical and molecular basis of gadolinium toxicity, possible clinical significance of gadolinium tissue retention and accumulation, and methods that can limit gadolinium body burden.