Absence of dentate nucleus resting-state functional connectivity changes in nonneurological patients with gadolinium-related hyperintensity on T1 -weighted images

Update on Gadolinium-Based Contrast Agent Safety, From the AJR Special Series on Contrast Media

Since its introduction more than 35 years ago, gadolinium-enhanced MRI has fundamentally changed medical practice. Although extraordinarily safe, gadolinium-based contrast agents (GBCAs) may have side effects. Four distinct safety considerations include acute allergiclike reactions, nephrogenic systemic fibrosis (NSF), gadolinium deposition, and symptoms associated with gadolinium exposure. Acute reactions after GBCA administration are uncommon-far less than with iodinated contrast agents-and, although rare, serious reactions can occur. NSF is a rare but serious sclerodermalike condition occurring in patients with kidney failure after exposure to American College of Radiology (ACR) group I GBCAs. Group II and III GBCAs are considered lower risk, and, through their use, NSF has largely been eliminated. Unrelated to NSF, retention of trace amounts of gadolinium in the brain and other organs has been recognized for over a decade. Deposition occurs with all agents, although linear agents appear to deposit more than macrocyclic agents. Importantly, to date, no data show any adverse biologic or clinical effects from gadolinium deposition, even with normal kidney function. This article summarizes the latest safety evidence of commercially available GBCAs with a focus on new agents, discusses updates to the ACR NSF GBCA safety classifications, and describes approaches for strengthening the evidence needed for regulatory decisions.

Use of gadolinium-based contrast agents in multiple sclerosis: a review by the ESMRMB-GREC and ESNR Multiple Sclerosis Working Group

Magnetic resonance imaging (MRI) is the most sensitive technique for detecting inflammatory demyelinating lesions in multiple sclerosis (MS) and plays a crucial role in diagnosis and monitoring treatment effectiveness, and for predicting the disease course. In clinical practice, detection of MS lesions is mainly based on T2-weighted and contrast-enhanced T1-weighted sequences. Contrast-enhancing lesions (CEL) on T1-weighted sequences are related to (sub)acute inflammation, while new or enlarging T2 lesions reflect the permanent footprint from a previous acute inflammatory demyelinating event. These two types of MRI features provide redundant information, at least in regular monitoring of the disease. Due to the concern of gadolinium deposition after repetitive injections of gadolinium-based contrast agents (GBCAs), scientific organizations and regulatory agencies in Europe and North America have proposed that these contrast agents should be administered only if clinically necessary. In this article, we provide data on the mode of action of GBCAs in MS, the indications of the use of these agents in clinical practice, their value in MS for diagnostic, prognostic, and monitoring purposes, and their use in specific populations (children, pregnant women, and breast-feeders). We discuss imaging strategies that achieve the highest sensitivity for detecting CELs in compliance with the safety regulations established by different regulatory agencies. Finally, we will briefly discuss some alternatives to the use of GBCA for detecting blood-brain barrier disruption in MS lesions. CLINICAL RELEVANCE STATEMENT: Although use of GBCA at diagnostic workup of suspected MS is highly valuable for diagnostic and prognostic purposes, their use in routine monitoring is not mandatory and must be reduced, as detection of disease activity can be based on the identification of new or enlarging lesions on T2-weighted images. KEY POINTS: • Both the EMA and the FDA state that the use of GBCA in medicine should be restricted to clinical scenarios in which the additional information offered by the contrast agent is required. • The use of GBCA is generally recommended in the diagnostic workup in subjects with suspected MS and is generally not necessary for routine monitoring in clinical practice. • Alternative MRI-based approaches for detecting acute focal inflammatory MS lesions are not yet ready to be used in clinical practice.

Where does the gadolinium go? A review into the excretion and retention of intravenous gadolinium

Gadolinium-based contrast agents (GBCAs) are commonly used in medical imaging. Most intravenously (IV) administered gadolinium is excreted via the kidneys, and pathological retention in renal failure leading to nephrogenic systemic fibrosis (NSF) is well described. More recently, retention of gadolinium in the body in the absence of renal disease has been identified, with unknown clinical consequences. Many patients are aware of this, either through the media or via comprehensive consent documentation. Some internet sites, without hard evidence, have suggested a constellation of possible symptoms associated with GBCA retention. Recent experience with patients ascribing symptoms to a contrast-enhanced MRI examination prompted this review of the fate of injected GBCA after MRI study, and of information available to patients online regarding gadolinium retention.

MR Imaging Signs of Gadolinium Retention Are Not Associated with Long-Term Motor and Cognitive Outcomes in Multiple Sclerosis

BACKGROUND AND PURPOSE

The long-term impact of gadolinium retention in the dentate nuclei of patients undergoing administration of seriate gadolinium-based contrast agents is still widely unexplored. The aim of this study was to evaluate the impact of gadolinium retention on motor and cognitive disability in patients with MS during long-term follow-up.

MATERIALS AND METHODS

In this retrospective study, clinical data were obtained from patients with MS followed in a single center from 2013 to 2022 at different time points. These included the Expanded Disability Status Scale score to evaluate motor impairment and the Brief International Cognitive Assessment for MS battery to investigate cognitive performances and their respective changes with time. The association with qualitative and quantitative MR imaging signs of gadolinium retention (namely, the presence of dentate nuclei T1-weighted hyperintensity and changes in longitudinal relaxation R1 maps, respectively) was probed using different General Linear Models and regression analyses.

RESULTS

No significant differences in motor or cognitive symptoms emerged between patients showing dentate nuclei hyperintensity and those without visible changes on T1WIs (P  = .14 and 0.92, respectively). When we tested possible relationships between quantitative dentate nuclei R1 values and both motor and cognitive symptoms, separately, the regression models including demographic, clinical, and MR imaging features explained 40.5% and 16.5% of the variance, respectively, without any significant effect of dentate nuclei R1 values (P  = .21 and 0.30, respectively).

CONCLUSIONS

Our findings suggest that gadolinium retention in the brains of patients with MS is not associated with long-term motor or cognitive outcomes.

Brain functional connectivity differences between responders and non-responders to sleeve gastrectomy

PURPOSE

To compare resting-state functional connectivity (RSFC) of obese patients responders or non-responders to sleeve gastrectomy (SG) with a group of obese patients with no past medical history of metabolic or bariatric surgery.

METHODS

MR images were acquired at 1.5 Tesla. Resting-state fMRI data were analyzed with statistical significance threshold set at p < 0.05, family-wise error (FWE) corrected.

RESULTS

Sixty-two subjects were enrolled: 20 controls (age range 25-64; 14 females), 24 responders (excess weight loss > 50%; age range 23-68; 17 females), and 18 non-responders to sleeve gastrectomy (SG) (excess weight loss < 50%; age range 23-67; 13 females). About within-network RSFC, responders showed significantly lower RSFC with respect to both controls and non-responders in the default mode and frontoparietal networks, positively correlating with psychological scores. Non-responders showed significantly higher (p < 0.05, family-wise error (few) corrected) RSFC in regions of the lateral visual network as compared to controls. Regarding between-network RSFC, responders showed significantly higher anti-correlation between executive control and salience networks (p < 0.05, FWE corrected) with respect to both controls and non-responders. Significant positive correlation (Spearman rho = 0.48, p = 0.0012) was found between % of excess weight loss and executive control-salience network RSFC.

CONCLUSION

There are differences in brain functional connectivity in either responders or non-responders patients to SG. The present results offer new insights into the neural correlates of outcome in patients who undergo SG and expand knowledge about neural mechanisms which may be related to surgical response.

Screening Breast MRI and Gadolinium Deposition: Cause for Concern?

Gadolinium-based contrast agents (GBCAs) have been used worldwide for over 30 years and have enabled lifesaving diagnoses. Contrast-enhanced breast MRI is frequently used as supplemental screening for women with an elevated lifetime risk of breast cancer. Data have emerged that indicate a fractional amount of administered gadolinium is retained in the bone, skin, solid organs, and brain tissues of patients with normal renal function, although there are currently no reliable data regarding the clinical or biological significance of this retention. Linear GBCAs are associated with a higher risk of gadolinium retention than macrocyclic agents. Over the course of their lives, screened women may receive high cumulative doses of GBCA. Therefore, as breast MRI screening utilization increases, thoughtful use of GBCA is indicated in this patient population.

MR Imaging Safety Considerations of Gadolinium-Based Contrast Agents: Gadolinium Retention and Nephrogenic Systemic Fibrosis

Gadolinium (Gd)-based contrast agents (GBCAs) have revolutionized of MR imaging, enabling physicians to obtain life-saving medical information that often cannot be obtained with unenhanced MR imaging or other imaging modalities. Since regulatory approval in 1988, more than 450 million intravenous GBCA doses have been administered worldwide, with an extremely favorable pharmacologic safety profile. Recent evidence has demonstrated, however, that a small fraction of Gd is retained in human tissues. No direct correlation between Gd retention and clinical effects has been confirmed; however, a subset of patients have attributed various symptoms to GBCA exposure. This review details current knowledge regarding GBCA safety.

Structural and functional changes in the brain of patients with Crohn's disease: an activation likelihood estimation meta-analysis

Multiple reports for brain functional and structural alterations in patients with Crohn's disease (CD) were published. The current study aimed to meta-analyze the existing neuroimaging data and hence produce a brain map revealing areas with functional and structural differences between patients with CD and healthy controls. Original studies published until 2019 were identified from Scopus, Web of Science and PubMed databases, and included into the analysis if they reported relevant results from task-related or resting state functional magnetic resonance imaging (fMRI or rsfMRI) or voxel-based morphometry (VBM), in the form of standardized brain coordinates based on whole-brain analysis. The brain coordinates and sample size of significant results were extracted from eligible studies to be meta-analyzed with the activation likelihood estimation method using the GingerALE software. Sixteen original studies comprised of a total of 865 participants fulfilled the inclusion criteria. Compared to healthy controls, patients with CD had reduced resting state brain connectivity in the paracentral lobule and cingulate gyrus as well as reduced grey matter volume in the medial frontal gyrus. No significant results were found vice versa. These neural correlates allow a better understanding on the effects of CD on the pain expectation, emotion, and quality of life of patients and potentially serve as useful biomarkers for evaluating treatment efficacy.

Changes in the anterior cingulate cortex in Crohn's disease: A neuroimaging perspective

INTRODUCTION

Evidence suggests that Crohn's disease (CD) pathophysiology goes beyond the gastrointestinal tract and is also strongly associated with the brain. In particular, the anterior cingulate cortex (ACC), which plays an integral role in the first brain as part of the default mode network (DMN) and pain matrix, shows abnormalities using multiple neuroimaging modalities. This review summarizes nine related studies that investigated changes in the ACC using structural magnetic resonance imaging, resting-state functional magnetic resonance imaging, and magnetic resonance spectroscopy.

METHODS

An extensive PubMed literature search was conducted from 1980 to August 2020. In a review of the articles identified, particular attention was paid to analysis methods, technical protocol characteristics, and specific changes in the ACC.

RESULTS

In terms of morphology, a decrease in gray matter volume and cortical thickness was observed along with an increase in local gyrification index. In terms of function, functional connectivity (FC) within the DMN was increased. FC between the ACC and the amygdala was decreased. Higher amplitudes of low-frequency fluctuation and graph theory results, including connectivity strength, clustering coefficient, and local efficiency, were detected. In terms of neurotransmitter changes, the concentrations of glutamate increased along with a decrease in gamma-aminobutyric acid, providing a rational explanation for abdominal pain. These changes may be attributed to stress, pain, and negative emotions, as well as changes in gut microbiota.

CONCLUSIONS

For patients with CD, the ACC demonstrates structural, functional, and metabolic changes. In terms of clinical findings, the ACC plays an important role in the onset of depression/anxiety and abdominal pain. Therefore, successful modulation of this pathway may guide treatment.

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.

Anterior pituitary gland T1 signal intensity is influenced by time delay after injection of gadodiamide

To test the hypothesis of washout from the anterior pituitary (AP) gland after serial injections of gadodiamide. We included 59 patients with history of at least 5 injections of gadodiamide. Values of mean signal intensity of the AP and of the central pons were measured on unenhanced sagittal T1-weighted images. AP-to-pons signal intensity ratios were calculated dividing the values of the AP by those of the pons. The measurements were performed using MR images acquired at four different time points including baseline (prior to any gadodiamide injection), minimum post-injection time delay, maximum post-injection time delay, and last available MR scans. Normalized ratios (i.e. ratios divided total volume of injected gadodiamide) were also calculated. To assess the difference between ratios, non-parametric Wilcoxon signed-rank test was applied. The correlations were tested with non-parametric Spearman correlation coefficient. A p-value < 0.05 was considered as statistically significant. A statistically significant increase of AP signal intensity was found by comparing the baseline scans with both the minimum time delay (p = 0.003) and maximum time delay scans (p = 0.005). We found significant higher normalized ratios for minimum post-injection time delay with respect to maximum post-injection time delay (p < 0.001). The normalized ratios demonstrated a statistically significant negative correlation with the post-injection time delay (r = − 0.31; p = 0.006). The findings of this study suggest that washout phenomena of retained/deposited gadolinium from the AP are influenced by the total injected volume and post-injection time delay.

Within-network brain connectivity in Crohn's disease patients with gadolinium deposition in the cerebellum

PURPOSE

Patients with Crohn's disease (CD) undergo multiple gadolinium-based contrast agent injections across their lifespan to enhance signal intensity of the intestinal wall and differentiate active from quiescent inflammatory disease. Thus, CD patients are prone to gadolinium accumulation in the brain and represent a non-neurological population to explore gadolinium-related brain toxicity. Possible effects are expected to be greater on the cerebellar network due to the high propensity of the dentate nucleus to accumulate gadolinium. Herein, we provide a whole-brain network analysis of resting-state fMRI dynamics in long-term quiescent CD patients with normal renal function and MRI evidence of gadolinium deposition in the brain.

METHODS

Fifteen patients with CD and 16 healthy age- and gender-matched controls were enrolled in this study. Relevant resting-state networks (RSNs) were identified using independent component analysis (ICA) from functional magnetic resonance imaging data. An unpaired two-sample t test (with age and sex as nuisance variables) was used to investigate between different RSNs. Clusters were determined by using threshold-free cluster enhancement and a family-wise error corrected cluster significance threshold of p < 0.05.

RESULTS

Patients showed significantly decreased resting-state functional connectivity (p < 0.05, FWE corrected) of several regions of the right frontoparietal (FPR) and the dorsal attention (DAN) RSNs. No differences between the two groups were found in the functional connectivity maps of all the other RSNs, including the cerebellar network.

CONCLUSION

Our findings suggest a non-significant impact of gadolinium deposition on within-network cerebellar functional connectivity of long-term quiescent CD patients.

Analysis of retention of gadolinium by brain, bone, and blood following linear gadolinium-based contrast agent administration in rats with experimental sepsis

PURPOSE

It is important to identify populations that may be vulnerable to the brain deposition of gadolinium (Gd) from MRI contrast agents. At intervals from 24 hours to 6 weeks following injection of a linear Gd contrast agent, the brain, blood and bone content of Gd were compared between control rats and those with experimental endotoxin-induced sepsis that results in neuroinflammation and blood-brain barrier disruption.

METHODS

Male rats were injected intraperitoneally with 10 mg/kg lipopolysaccharide. Control animals received no injection. Twenty-four hours later, 0.2 mmol/kg of gadobenate dimeglumine was injected intravenously. Brain, blood, and bone Gd levels were measured at 24 hours, 1 week, 3 weeks, and 6 weeks by inductively coupled plasma mass spectroscopy.

RESULTS

Blood Gd decreased rapidly between 24 hours and 1 week, and thereafter was undetectable, with no significant difference between lipopolysaccharide and control rats. Brain levels of Gd were significantly higher (4.29-2.36-fold) and bone levels slightly higher (1.35-1.11-fold) in lipopolysaccharide than control rats at all time points with significant retention at 6 weeks.

CONCLUSION

Experimental sepsis results in significantly higher deposition of Gd in the brain and bone in rats. While blood Gd clears rapidly, brain and bone retained substantial Gd even at 6 weeks following contrast injection.

Prospective Multicenter Study of the Safety of Gadoteridol in 6163 Patients

Background

The safety of gadolinium‐based contrast agents is of fundamental importance.

Purpose

To determine the frequency and severity of immediate‐type adverse reactions to approved doses of gadoteridol in patients referred for routine gadoteridol‐enhanced MRI in actual clinical practice settings.

Study Type

Prospective, observational.

Population

In all, 6163 subjects were enrolled (mean age: 56.7 ± 15.4 years; range: 6–93 years).

Field Strength/Sequence

1.5T and 3.0T.

Assessment

Assessment was of immediate adverse reactions by the investigating radiologist using the MedDRA System Organ Class and preferred term.

Statistical Tests

Summary statistics for continuous variables, descriptive statistics for demographic characteristics.

Results

Overall, 19 adverse events occurred in 13 (0.21%) patients, of which 15 in 10 (0.16%) patients were considered related to gadoteridol administration. These events were evenly distributed between male and female subjects and all occurred in adults. Twelve of the 15 related events in eight (0.13%) patients were considered mild in intensity (rapidly self‐resolving), while the remaining three events in two patients (0.03%) were considered moderate in intensity. None were of severe intensity and no serious adverse events occurred.

Data Conclusion

The rate of immediate‐type adverse events following exposure to approved doses of gadoteridol is extremely low, and mostly limited to transient and self‐resolving symptoms.

Level of Evidence: 2

Technical Efficacy Stage: 5

J. Magn. Reson. Imaging 2020;51:861–868.

Visible T1-hyperintensity of the dentate nucleus after multiple administrations of macrocyclic gadolinium-based contrast agents: yes or no?

OBJECTIVES

To investigate the appearance of visible dentate nucleus (DN) T1-hyperintensity and quantify changes in DN/pons (DN/P) signal intensity (SI) ratio in MS patients after the exclusive administration of macrocyclic GBCAs.

MATERIALS AND METHODS

One hundred forty-nine patients with confirmed MS were evaluated. Patients received at least two administrations of gadobutrol (n = 63), gadoterate (n = 57), or both (n = 29). Two experienced neuroradiologists in consensus evaluated unenhanced T1-weighted MR images from all examinations in each patient for evidence of visible DN hyperintensity. Thereafter, SI measurements were made in the left and right DN and pons on unenhanced T1-weighted images from the first and last scans. A two-sample t test compared the DN/P SI ratios for patients with and without visible T1-hyperintensity.

RESULTS

Visible T1-hyperintensity was observed in 42/149 (28.2%) patients (19 after gadobutrol only, 15 after gadoterate only, 8 after both), typically at the 4th or 5th follow-up exam at 3-4 years after the initial examination. Significant increases in DN/P SI ratio from first to last examination were determined for patients with visible T1-hyperintensity (0.998 ± 0.002 to 1.153 ± 0.016, p < 0.0001 for gadobutrol; 1.003 ± 0.004 to 1.110 ± 0.014, p < 0.0001 for gadoterate; 1.004 ± 0.011 to 1.163 ± 0.032, p = 0.0004 for both) but not for patients without visible T1-hyperintensity (p > 0.05; all groups).

CONCLUSION

Multiple injections of gadobutrol and/or gadoterate can lead to visible and quantifiable increases in DN/P SI ratio in some patients with MS.

Gadolinium Retention in the Brain: An MRI Relaxometry Study of Linear and Macrocyclic Gadolinium-Based Contrast Agents in Multiple Sclerosis

BACKGROUND AND PURPOSE

Brain gadolinium retention is consistently reported for linear gadolinium-based contrast agents, while the results for macrocyclics are contradictory and potential clinical manifestations remain controversial. Furthermore, most previous studies are based on conventional T1-weighted MR imaging. We therefore aimed to quantitatively investigate longitudinal and transversal relaxation in the brain in relation to previous gadolinium-based contrast agent administration and explore associations with disability in multiple sclerosis.

MATERIALS AND METHODS

Eighty-five patients with MS and 21 healthy controls underwent longitudinal and transverse relaxation rate (R₁ and R₂) relaxometry. Patients were divided into linear, mixed, and macrocyclic groups based on previous gadolinium-based contrast agent administration. Neuropsychological testing was performed in 53 patients. The dentate nucleus, globus pallidus, caudate nucleus, and thalamus were manually segmented. Repeatability measures were also performed.

RESULTS

The relaxometry was robust (2.0% scan-rescan difference) and detected higher R₁ (dentate nucleus, globus pallidus, caudate nucleus, thalamus) and R₂ (globus pallidus, caudate nucleus) in patients receiving linear gadolinium-based contrast agents compared with controls. The number of linear gadolinium-based contrast agent administrations was associated with higher R₁ and R₂ in all regions (except R₂ in the thalamus). No similar differences and associations were found for the macrocyclic group. Higher relaxation was associated with lower information-processing speed (dentate nucleus, thalamus) and verbal fluency (caudate nucleus, thalamus). No associations were found with physical disability or fatigue.

CONCLUSIONS

Previous linear, but not macrocyclic, gadolinium-based contrast agent administration is associated with higher relaxation rates in a dose-dependent manner. Higher relaxation in some regions is associated with cognitive impairment but not physical disability or fatigue in MS. The findings should be interpreted with care but encourage studies into gadolinium retention and cognition.