Is Small Fiber Neuropathy Induced by Gadolinium-Based Contrast Agents?

Effects of Gadolinium Retention in the Brains of Type 2 Diabetic Rats after Repeated Administration of Gadolinium-Based MRI Contrast Agents on Neurobiology and NLRP3 Inflammasome Activation

BACKGROUND

The neurotoxic potential of gadolinium (Gd)-based contrast agents (GBCAs) retention in the brains of patients with type 2 diabetes mellitus (T2DM) is unclear.

PURPOSE

To determine the deposition and clearance of GBCAs in T2DM rats and the mechanism by which Gd enhances nucleotide-binding oligomerization domain-3 (NLRP3) inflammasome activation.

STUDY TYPE

Cross-sectional, prospective.

ANIMAL MODEL

104 T2DM male Wistar rats.

FIELD STRENGTH/SEQUENCE

9.4-T, T1-weighted fast spin echo sequence.

ASSESSMENT

T2DM (male Wistar rats, n = 52) and control group (healthy, male Wistar rats, n = 52) rats received saline, gadodiamide, Gd-diethylenetriaminepentaacetic acid, and gadoterate meglumine for four consecutive days per week for 7 weeks. The distribution and clearance of Gd in the certain brain were assessed by MRI (T1 signal intensity and relaxation rate R1, on the last day of each week), inductively coupled plasma mass-spectroscopy, ultraperformance liquid chromatography mass spectrometry, and transmission electron microscopy. Behavioral tests, histopathological features, and the effects of GBCAs on neuroinflammation were also analyzed.

STATISTICAL TESTS

One-way analysis of variance, bonferroni method, and unpaired t-test. A P-value <0.05 was considered statistically significant.

RESULTS

The movement distance and appearance time in the open field test of the T2DM rats in the gadodiamide group were significantly shorter than in the other groups. Furthermore, the expression of NLRP3, Pro-Caspase-1, interleukin-1β (IL-1β), and apoptosis-associated speck-like protein containing a CARD protein in neurons was significantly higher in the gadodiamide group than in the saline group, as shown by Western blot. Gadodiamide also induced differentiation of microglia into M1 type, decreased the neuronal mitochondrial membrane potential, and significantly increased neuronal apoptosis from flow cytometry.

DATA CONCLUSION

T2DM may affect both the deposition and clearance of GBCAs in the brain. Informed by the T2DM model, gadodiamide could mediate the neuroinflammatory response by NLRP3 inflammasome activation.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY: Stage 1.

Divalent Manganese Complexes as Potential Replacements for Gadolinium-Based Contrast Agents

ABSTRACT

Recent safety concerns surrounding the use of gadolinium-based contrast agents (GBCAs) have spurred research into identifying alternatives to GBCAs for use with magnetic resonance imaging. This review summarizes the molecular and pharmaceutical properties of a GBCA replacement and how these may be achieved. Complexes based on high-spin, divalent manganese (Mn 2+ ) have shown promise as general purpose and liver-specific contrast agents. A detailed description of the complex Mn-PyC3A is provided, describing its physicochemical properties, its behavior in different animal models, and how it compares with GBCAs. The review points out that, although there are parallels with GBCAs in how the chemical properties of Mn 2+ complexes can predict in vivo behavior, there are also marked differences between Mn 2+ complexes and GBCAs.

Gadolinium Presence in Rat Skin: Assessment of Histopathologic Changes Associated with Small Fiber Neuropathy

Background The presence of gadolinium traces in the skin after administration of gadolinium-based contrast agents (GBCAs) raised safety concerns regarding a potential association with small fiber neuropathy (SFN). Purpose To investigate signs of SFN in rat foot pads by quantification of the intraepidermal nerve fiber density (IENFD) after multiple GBCA administrations and to evaluate gadolinium concentration, chemical species, and clearance. Materials and Methods Fifty rats received eight intravenous injections of either gadodiamide, gadobutrol, gadoterate, gadoteridol (8 × 0.6 mmol per kilogram of body weight), or saline (1.2 mL per kilogram of body weight), within 2 weeks and were sacrificed 5 days or 5 weeks after the last injection. IENFD was determined with protein gene product (PGP) 9.5 immunofluorescent staining and blinded and automated image analysis. The gadolinium and GBCA concentrations were measured with inductively coupled plasma mass spectrometry (ICP-MS), laser ablation ICP-MS, and matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI). P values were calculated using linear contrasts of model analysis. Results The IENFD (measured as geometric mean [SD] and in number of nerve fibers per millimeter of epidermis) was not significantly altered after 5 days (saline, 8.4 [1.1]; gadobutrol, 9.7 [1.2]; gadoterate, 9.2 [1.2]; gadoteridol, 9.9 [1.3]; gadodiamide, 10.5 [1.2]) or 5 weeks (saline, 19.7 [1.4]; gadobutrol, 16.4 [1.6]; gadoterate, 14.3 [1.6]; gadoteridol, 22.2 [1.8]; gadodiamide, 17.9 [1.4]). Gadolinium skin concentrations were highest for gadodiamide after 5 days (16.0 nmol/g [1.1]) and 5 weeks (10.6 nmol/g [1.2], -33%). Macrocyclic agents were lower at 5 days (gadoteridol, 2.6 nmol/g [1.2]; gadobutrol, 2.7 nmol/g [1.1]; and gadoterate, 2.3 nmol/g [1.2]) and efficiently cleared after 5 weeks (gadoteridol, -95%; gadobutrol and gadoterate, -96%). The distribution of gadolinium and IENF did not visually overlap. For macrocyclic agents, gadolinium was found in sweat glands and confirmed to be intact chelate. Conclusion There were no signs of SFN in rat foot pads using multiple dosing regimens at two time points after administration of GBCAs. Macrocyclic GBCAs exhibited lower levels of gadolinium in the skin and were effectively eliminated within 5 weeks compared with linear gadodiamide, and intact macrocyclic GBCA was detected in sweat glands. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Clement in this issue.

Male spiny frogs enter the underwater battlefield with loose skin exhibiting enhanced penetration of capillaries into the epidermis

The skin has multiple functions, and capillaries can penetrate the epidermis to shorten the diffusion path while allowing maintenance of overall epidermal thickness for nonrespiratory roles. However, a method for quantifying the capillary penetration extent is lacking. Such a method may facilitate making comparisons and detecting associations, potentially making the extent a useful variable in biological studies. We quantified the extent as the ratio of the average minimum thickness of epidermis overlying each capillary to the average epidermal thickness along a skin section and then explored its performance in the Emei mustache toad, Leptobrachium boringii, a species in which breeding males with loose skin call and fight each other with maxillary spines underwater. The ratio showed informative associations with other variables, such as perfused capillary density. It displayed small intragroup variation and could be more sensitive than other variables in revealing structural differences in the skin. The ratio estimates were lowest and were correlated with epidermal and stratum compactum thicknesses in breeding males, i.e., a covariation but not reinforcement against stabbing, constituting early evidence consistent with the increased extensibility of loose skin conferring a defensive advantage during combat in amphibians. In addition, our results lead to the hypothesis that high hemoglobin density along subepidermal capillaries favors the maintenance of low blood partial oxygen pressure and hence increases cutaneous oxygen uptake. We also provide evidence supporting the new idea that the cooccurrence of loose skin and underwater calling found in some frogs can be explained by the latter benefiting from a large functional respiratory surface area. Awareness of the usefulness of the ratio may promote its application and the quantification of the penetration. Regarding exchange surface design, these findings for L. boringii imply a case in which looseness increases surface area as well as prevents damage.

Reduction of Gadolinium-Based Contrast Agents in MRI Using Convolutional Neural Networks and Different Input Protocols: Limited Interchangeability of Synthesized Sequences With Original Full-Dose Images Despite Excellent Quantitative Performance

OBJECTIVES

The purpose of this study was to implement a state-of-the-art convolutional neural network used to synthesize artificial T1-weighted (T1w) full-dose images from corresponding noncontrast and low-dose images (using various settings of input sequences) and test its performance on a patient population acquired prospectively.

MATERIALS AND METHODS

In this monocentric, institutional review board-approved study, a total of 138 participants were included who received an adapted imaging protocol with acquisition of a T1w low dose after administration of 10% of the standard dose and acquisition of a T1w full dose after administration of the remaining 90% of the standard dose of a gadolinium-containing contrast agent. A total of 83 participants formed the training sample (51.7 ± 16.5 years, 36 women), 25 the validation sample (55.3 ± 16.4 years, 11 women), and 30 the test sample (55.0 ± 15.0 years, 9 women). Four input settings were differentiated: only the T1w noncontrast and T1w low-dose images (standard setting), only the T1w noncontrast and T1w low-dose images with a prolonged postinjection time of 5 minutes (5-minute setting), multiple noncontrast sequences (T1w, T2w, diffusion) and the T1w low-dose images (extended setting), and only noncontrast sequences (T1w, T2w, diffusion) were used (zero-dose setting). For each setting, a deep neural network was trained to synthesize artificial T1w full-dose images, which were assessed on the test sample using an objective evaluation based on quantitative metrics and a subjective evaluation through a reader-based study. Three readers scored the overall image quality, the interchangeability in regard to the clinical conclusion compared with the true T1w full-dose sequence, the contrast enhancement of lesions, and their conformity to the respective references in the true T1w full dose.

RESULTS

Quantitative analysis of the artificial T1w full-dose images of the standard setting provided a peak signal-to-noise ratio of 33.39 ± 0.62 (corresponding to an average improvement of the low-dose sequences of 5.2 dB) and a structural similarity index measure of 0.938 ± 0.005. In the 4-fold cross-validation, the extended setting yielded similar performance to the standard setting in terms of peak signal-to-noise ratio ( P = 0.20), but a slight improvement in structural similarity index measure ( P < 0.0001). For all settings, the reader study found comparable overall image quality between the original and artificial T1w full-dose images. The proportion of scans scored as fully or mostly interchangeable was 55%, 58%, 43%, and 3% and the average counts of false positives per case were 0.42 ± 0.83, 0.34 ± 0.71, 0.82 ± 1.15, and 2.00 ± 1.07 for the standard, 5-minute, extended, and zero-dose setting, respectively. Using a 5-point Likert scale (0 to 4, 0 being the worst), all settings of synthesized full-dose images showed significantly poorer contrast enhancement of lesions compared with the original full-dose sequence (difference of average degree of contrast enhancement-standard: -0.97 ± 0.83, P = <0.001; 5-minute: -0.93 ± 0.91, P = <0.001; extended: -0.96 ± 0.97, P = <0.001; zero-dose: -2.39 ± 1.14, P = <0.001). The average scores of conformity of the lesions compared with the original full-dose sequence were 2.25 ± 1.21, 2.22 ± 1.27, 2.24 ± 1.25, and 0.73 ± 0.93 for the standard, 5-minute, extended, and zero-dose setting, respectively.

CONCLUSIONS

The tested deep learning algorithm for synthesis of artificial T1w full-dose sequences based on images after administration of only 10% of the standard dose of a gadolinium-based contrast agent showed very good quantitative performance. Despite good image quality in all settings, both false-negative and false-positive signals resulted in significantly limited interchangeability of the synthesized sequences with the original full-dose sequences.

Elemental bioimaging and transcriptomics reveal unchanged gene expression in mouse cerebellum following a single injection of Gadolinium-based contrast agents

Gadolinium (Gd) deposition in the brain, first and foremost in the dentate nucleus in the cerebellum, following contrast enhanced MRI, rose awareness of potential adverse effects of gadolinium-based contrast agent (GBCA) administration. According to previous in vitro experiments, a conceivable side-effect of Gd deposition could be an alteration of gene expression. In the current study, we aimed to investigate the influence of GBCA administration on gene expression in the cerebellum of mice using a combination of elemental bioimaging and transcriptomics. In this prospective animal study, three groups of eight mice each were intravenously injected with either linear GBCA gadodiamide, macrocyclic GBCA gadoterate (1 mmol GBCA/kg body weight) or saline (NaCl 0.9%). Animals were euthanized four weeks after injection. Subsequently, Gd quantification via laser ablation-ICP-MS and whole genome gene expression analysis of the cerebellum were performed. Four weeks after single application of GBCAs to 24-31 days old female mice, traces of Gd were detectable in the cerebellum for both, the linear and macrocyclic group. Subsequent transcriptome analysis by RNA sequencing using principal component analysis did not reveal treatment-related clustering. Also differential expression analysis did not reveal any significantly differentially expressed genes between treatments.

Gadolinium retention in a rat model of subtotal renal failure: are there differences among macrocyclic GBCAs?

BACKGROUND

Gd levels are higher in tissues of animals with compromised renal function, but studies to compare levels after exposure to different macrocyclic gadolinium-based contrast agents (GBCAs) are lacking. We compared Gd levels in tissues of subtotally nephrectomised (SN) rats after repeated exposure to macrocyclic GBCAs.

METHODS

Sprague-Dawley SN male rats (19 per group) received 16 injections of gadoteridol, gadobutrol, or gadoterate meglumine at 0.6 mmol Gd/kg 4 times/weeks over 4 weeks. A control group of healthy male rats (n = 10) received gadoteridol at the same dosage. Plasma urea and creatinine levels were monitored. Blood, cerebrum, cerebellum, liver, femur, kidney(s), skin and peripheral nerves were harvested for Gd determination by inductively coupled plasma-mass spectrometry at 28 and 56 days after the end of treatment.

RESULTS

Plasma urea and creatinine levels were roughly twofold higher in SN rats than in healthy rats at all timepoints. At day 28, Gd levels in the peripheral nerves of gadobutrol- or gadoterate-treated SN animals were 5.4 or 7.2 times higher than in gadoteridol-treated animals (p < 0.001). Higher Gd levels after administration of gadobutrol or gadoterate versus gadoteridol were also determined in kidneys (p ≤ 0.002), cerebrum (p ≤ 0.001), cerebellum (p ≤ 0.003), skin (p ≥ 0.244), liver (p ≥ 0.053), and femur (p ≥ 0.271). At day 56, lower Gd levels were determined both in SN and healthy rats for all GBCAs and tissues, except the femur.

CONCLUSIONS

Gd tissue levels were lower following gadoteridol exposure than following gadobutrol or gadoterate exposure.

Gadolinium Retention in the Brain of Mother and Pup Mouse: Effect of Pregnancy and Repeated Administration of Gadolinium‐Based Contrast Agents

Background

The association of repeated administration of gadolinium‐based contrast agents (GBCAs) with the gadolinium (Gd) retention in the brains of mother and fetus remains unclear.

Purpose

To investigate the effects of pregnancy and repeated administration of GBCAs on Gd retention in the brains of mother and pup mice.

Study type

Cross‐sectional cohort toxicity study.

Animal Model

From gestational days 16–19, pregnant (n = 48) BALB/c mice.

Field Strength

A 9.4 T and fast spin echo sequence.

Assessment

Half of the mother mice (n = 24) were killed at postnatal day 1 (P1) for inductively coupled plasma mass spectrometry (ICP‐MS) and transmission electron microscopy (TEM). Besides the ICP‐MS and TEM, four pups were randomly selected from each mother and killed at P1 for ultraperformance liquid chromatography mass spectrometry (UPLC‐MS) and Nissl staining.

Statistical Tests

One‐way analysis of variance and unpaired t‐test.

Results

In the group of gadodiamide, retention of Gd in the brains of pregnant mice was significantly lower than that of nonpregnant mice in the area of the deep cerebellar nuclei (DCN) (10.35 ± 2.16 nmol/g vs. 18.74 ± 3.65 nmol/g). Retention of Gd in the DCN of pups whose mothers were administered gadoterate meglumine was significantly lower than that of pups whose mothers were administered gadodiamide (0.21 ± 0.09 nmol/g vs. 6.15 ± 3.21 nmol/g) at P1. In mice treated with gadodiamide, most of the retained Gd in the brain tissue was insoluble (19.5% ± 9.5% of the recovered amount corresponded to the intact complex in the DCN).

Data Conclusion

In different brain areas of the mother and pup mice, the retention of Gd after gadoterate meglumine administration was lower than that of gadodiamide and gadopentetate dimeglumine administration, and almost all the detected Gd in pups' brains was intact soluble GBCAs.

Evidence Level

1

Technical Efficacy

Stage 2

Gadolinium: pharmacokinetics and toxicity in humans and laboratory animals following contrast agent administration

Gadolinium-based contrast agents (GBCAs) have transformed magnetic resonance imaging (MRI) by facilitating the use of contrast-enhanced MRI to allow vital clinical diagnosis in a plethora of disease that would otherwise remain undetected. Although over 500 million doses have been administered worldwide, scientific research has documented the retention of gadolinium in tissues, long after exposure, and the discovery of a GBCA-associated disease termed nephrogenic systemic fibrosis, found in patients with impaired renal function. An understanding of the pharmacokinetics in humans and animals alike are pivotal to the understanding of the distribution and excretion of gadolinium and GBCAs, and ultimately their potential retention. This has been well studied in humans and more so in animals, and recently there has been a particular focus on potential toxicities associated with multiple GBCA administration. The purpose of this review is to highlight what is currently known in the literature regarding the pharmacokinetics of gadolinium in humans and animals, and any toxicity associated with GBCA use.

Altered Functional Mitochondrial Protein Levels in Plasma Neuron-Derived Extracellular Vesicles of Patients With Gadolinium Deposition

The retention of the heavy metal, gadolinium, after a Gadolinium-Based Contrast Agent-assisted MRI may lead to a symptom cluster termed Gadolinium Deposition Disease. Little is known of the disorder's underlying pathophysiology, but a recent study reported abnormally elevated serum levels of pro-inflammatory cytokines compared to normal controls. As a calcium channel blocker in cellular plasma and mitochondrial membranes, gadolinium also interferes with mitochondrial function. We applied to sera from nine Gadolinium Deposition Disease and two Gadolinium Storage Condition patients newly developed methods allowing isolation of plasma neuron-derived extracellular vesicles that contain reproducibly quantifiable levels of mitochondrial proteins of all major classes. Patients' levels of five mitochondrial functional proteins were statistically significantly lower and of two significantly higher than the levels in normal controls. The patterns of differences between study patients and controls for mitochondrial dynamics and mitochondrial proteins encompassing neuronal energy generation, metabolic regulation, ion fluxes, and survival differed from those seen for patients with first episode psychosis and those with Major Depressive Disorder compared to their controls. These findings suggest that mitochondrial dysfunction due to retained gadolinium may play a role in causing Gadolinium Deposition Disease. Larger samples of both GDD and GSC patients are needed to allow not only testing the repeatability of our findings, but also investigation of relationships of specific mitochondrial protein deficiencies or excesses and concurrent cytokine, genetic, or other factors to GDD's neurological and cognitive symptoms. Studies of neuronal mitochondrial proteins as diagnostic markers or indicators of treatment effectiveness are also warranted.

Symptoms Associated with Gadolinium Exposure (SAGE): A Suggested Term

In this article, members of the American College of Radiology Committee on Drugs and Contrast Media propose a new term for symptoms reported after intravascular exposure to gadolinium-based contrast agents-Symptoms Associated with Gadolinium Exposure, or SAGE. This term is advocated in lieu of other proposed nomenclature that presumes a causal relationship that has not yet been scientifically verified. The purpose of this new term, SAGE, is to assist researchers and clinical providers in describing such symptoms without prematurely causally attributing them to a disease and to standardize reporting of these symptoms to allow for coherent interpretation of related studies.

Gadolinium Tissue Distribution in a Large-Animal Model after a Single Dose of Gadolinium-based Contrast Agents

Background There is an ongoing scientific debate about the degree and clinical importance of gadolinium deposition in the brain and other organs after administration of gadolinium-based contrast agents (GBCAs). While most published data focus on gadolinium deposition in the brain, other organs are rarely investigated. Purpose To compare gadolinium tissue concentrations in various organs 10 weeks after one injection (comparable to a clinically applied dose) of linear and macrocyclic GBCAs in a large-animal model. Materials and Methods In this prospective animal study conducted from March to May 2018, 36 female Swiss-Alpine sheep (age range, 4-10 years) received one injection (0.1 mmol/kg) of macrocyclic GBCAs (gadobutrol, gadoteridol, and gadoterate meglumine), linear GBCAs (gadodiamide and gadobenate dimeglumine), or saline. Ten weeks after injection, sheep were sacrificed and tissues were harvested. Gadolinium concentrations were quantified with inductively coupled plasma mass spectrometry (ICP-MS). Histologic staining was performed. Data were analyzed with nonparametric tests. Results At 10 weeks after injection, linear GBCAs resulted in highest mean gadolinium concentrations in the kidney (502 ng/g [95% CI: 270, 734]) and liver (445 ng/g [95% CI: 202, 687]), while low concentrations were found in the deep cerebellar nuclei (DCN) (30 ng/g [95% CI: 20, 41]). Tissue concentrations of linear GBCAs were three to 21 times higher compared with those of macrocyclic GBCAs. Administered macrocyclic GBCAs resulted in mean gadolinium concentrations of 86 ng/g (95% CI: 31, 141) (P = .08) in the kidney, 21 ng/g (95% CI: 4, 39) (P = .15) in liver tissue, and 10 ng/g (95% CI: 9, 12) (P > .99) in the DCN, which were not significantly elevated when compared with concentrations in control animals. No histopathologic alterations were observed irrespective of tissue concentrations within any examined organ. Conclusion Ten weeks after one injection of a clinically relevant dose of gadolinium-based contrast agents, the liver and kidney appeared to be reservoirs of gadolinium; however, despite gadolinium presence, no tissue injury was detected. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Clément in this issue.

Comprehensive phenotyping revealed transient startle response reduction and histopathological gadolinium localization to perineuronal nets after gadodiamide administration in rats

Gadolinium based contrast agents (GBCAs) are widely used in clinical MRI since the mid-1980s. Recently, concerns have been raised that trace amounts of Gadolinium (Gd), detected in brains even long time after GBCA application, may cause yet unrecognized clinical consequences. We therefore assessed the behavioral phenotype, neuro-histopathology, and Gd localization after repeated administration of linear (gadodiamide) or macrocyclic (gadobutrol) GBCA in rats. While most behavioral tests revealed no difference between treatment groups, we observed a transient and reversible decrease of the startle reflex after gadodiamide application. Residual Gd in the lateral cerebellar nucleus was neither associated with a general gene expression pathway deregulation nor with neuronal cell loss, but in gadodiamide-treated rats Gd was associated with the perineuronal net protein aggrecan and segregated to high molecular weight fractions. Our behavioral finding together with Gd distribution and speciation support a substance class difference for Gd presence in the brain after GBCA application.

Gadolinium-based contrast agents: What we learned from acute adverse events, nephrogenic systemic fibrosis and brain retention

BACKGROUND

 Radiologists have been administering gadolinium-based contrast agents (GBCA) in magnetic resonance imaging for several decades, so that there is abundant experience with these agents regarding allergic-like reactions, nephrogenic systemic fibrosis (NSF) and gadolinium retention in the brain.

METHODS

 This review is based on a selective literature search and reflects the current state of research on acute adverse effects of GBCA, NSF and brain retention of gadolinium.

RESULTS

 Due to the frequent use of GBCA, data on adverse effects of these compounds are available in large collectives. Allergic-like reactions occurred rarely, whereas severe acute reactions were very rarely observed. Systemic changes in NSF also occur very rarely, although measures to avoid NSF resulted in a significantly reduced incidence of NSF. Due to gadolinium retention in the body after administration of linear MR contrast agents, only macrocyclic preparations are currently used with few exceptions. Clear clinical correlates of gadolinium retention in the brain could not be identified so far. Although the clinical added value of GBCA is undisputed, individual risks associated with the injection of GBCA should be identified and the use of non-contrast enhanced MR techniques should be considered. Alternative contrast agents such as iron oxide nanoparticles are not clinically approved, but are currently undergoing clinical trials.

CONCLUSION

 GBCA have a very good risk profile with a low rate of adverse effects or systemic manifestations such as NSF. Gadolinium retention in the brain can be minimized by the use of macrocyclic GBCA, although clear clinical correlates due to gadolinium retention in the brain following administration of linear GBCA could not be identified yet.

KEY POINTS

· Acute adverse effects are predominantly mild/moderate, rarely severe reactions occur.. · International guidelines resulted in significant reduction of nephrogenic systemic fibrosis.. · Application of macrocyclic contrast agents minimizes gadolinium retention in the brain..

CITATION FORMAT

· Bäuerle T, Saake M, Uder M. Gadolinium-based contrast agents: What we learned from acute adverse events, nephrogenic systemic fibrosis and brain retention. Fortschr Röntgenstr 2021; 193: 1010 - 1018.