Does renal function affect gadolinium deposition in the brain?

Gadolinium and Bio-Metal Association: A Concentration Dependency Tested in a Renal Allograft and Investigated by Micro-Synchrotron XRF

Aims: This study aimed to investigate gadolinium (Gd) and bio-metals in a renal allograft of a patient who was shortly after transplantation repeatedly exposed to a Gd-based contrast agent (GBCA), with the purpose of determining whether Gd can be proven and spatially and quantitatively imaged. Further elemental associations between Gd and bio-metals were also investigated. Materials and Methods: Archival paraffin-embedded kidney tissue (eight weeks after transplantation) was investigated by microscopic synchrotron X-ray fluorescence (µSRXRF) at the DORIS III storage ring, beamline L, at HASYLAB/DESY (Hamburg, Germany). For the quantification of elements, X-ray spectra were peak-fitted, and the net peak intensities were normalized to the intensity of the incoming monochromatic beam intensity. Concentrations were calculated by fundamental parameter-based program quant and external standardization. Results: Analysis of about 15,000 µSRXRF spectra (comprising allograft tissue of four cm²) Gd distribution could be quantitatively demonstrated in a near histological resolution. Mean Gd resulted in 24 ± 55 ppm with a maximum of 2363 ppm. The standard deviation of ±55 ppm characterized the huge differences in Gd and not in detection accuracy. Gd was heterogeneously but not randomly distributed and was mostly found in areas with interstitial fibrosis and tubular atrophy. Concentrations of all other investigated elements in the allograft resembled those found in normal kidney tissue. No correlations between Gd and bio-metals such as calcium, strontium or zinc below ~40 ppm Gd existed. In areas with extremely high Gd, Gd was associated with iron and zinc. Conclusions: We could show that no dose-dependent association between Gd and bio-metals exists—least in renal tissue—at Gd concentrations below ~40 ppm Gd. This was proven compared with a GBCA-exposed end-stage renal failure in which the mean Gd was ten-fold higher. Our results could shed additional light on Gd metabolism.

Evaluation of the effect of multiple administrations of gadopentetate dimeglumine or gadoterate meglumine on brain T1-weighted hyperintensity in pediatric patients

BACKGROUND

Repeated administrations of linear gadolinium-based contrast media (GBCM) are associated with T1-weighted (T1-W) signal intensity change in brain structures.

OBJECTIVE

The purpose of this study was to compare different brain structures in children after unconfounded, repeated administrations of either a macrocyclic or linear GBCM.

MATERIALS AND METHODS

We performed a retrospective cohort study, identifying subjects with ≥5 unconfounded administrations of gadoterate meglumine. We matched subjects with repeated administrations of gadopentetate dimeglumine to the gadoterate meglumine arm based on the number of unconfounded GBCM administrations. Two reviewers drew regions of interest on 27 structures in and around the brain. We recorded demographic, modality and study parameters and evaluated them to determine whether they were associated with T1-W signal intensity (SI) changes. Linear mixed effects models evaluated the relationships between the number of GBCM doses and T1-W SI ratio. Finally, we identified differences in the rate of T1-W SI ratio change among individuals using a linear mixed effects model with random slope.

RESULTS

We included a total of 52 patients (age range at first MRI: 6.0 months to 17.1 years), 26 in each arm. We detected a significant change in the T1-W SI ratio with repeated administrations of GBCM in one location in the gadoterate meglumine arm and in four locations in the gadopentetate dimeglumine arm. Patient gender and age were not associated with T1-W SI change. Modality vendor, imaging sequence and field strength were variably associated with a systematic difference in the ability to detect a T1-W SI change. Finally, linear mixed effects model with random slope showed that there were individual differences in the slope of SI change at various structures among individuals for both arms. This effect was present in more brain structures in the gadopentetate dimeglumine arm (14 vs. 8).

CONCLUSION

There is a significant change in the T1-W SI ratio over time in multiple brain structures after repeated gadopentetate dimeglumine administrations. This effect was only seen in one ratio after repeated administrations of gadoterate meglumine. There are individual differences in the rate of change of SI ratios over time after repeated administration of gadopentetate dimeglumine and gadoterate meglumine, suggesting that individual differences are present.

A retrospective cohort evaluation of the effect of multiple administrations of gadopentetate dimeglumine on brain magnetic resonance imaging T1-weighted signal

BACKGROUND

Gadolinium deposition occurs following repeated administration of gadolinium-based contrast media. However, few studies have evaluated factors that lead to increased detection of deposition or the individual differences among patients.

OBJECTIVE

To measure the effect of repeated dosages of gadopentetate dimeglumine on pediatric brains and to determine the factors that influence signal intensity changes.

MATERIALS AND METHODS

A retrospective study evaluated magnetic resonance imaging (MRI) in patients <18 years of age who received >5 doses of gadopentetate dimeglumine. Regions of interest were placed in 30 locations in the brain on axial precontrast T1 images. Signal intensity ratios were evaluated throughout the brain. The effect of increasing gadopentetate dimeglumine exposure on signal intensity ratios was assessed using linear mixed models adjusted for gender, age, imaging sequence type (fast spin echo or gradient echo), MRI manufacturer (General Electric, Philips or Siemens), and field strength (1.5 tesla [T] or 3 T). Finally, the variance of the random slope in the linear mixed models was tested to determine if there were differences in the rate of signal intensity ratio change among individuals.

RESULTS

Fifty patients (M:F=25:25; mean age at first imaging: 6.4 years) with a mean of 21.5 gadopentetate dimeglumine administrations (range: 6-86) were included. There were significant increases in T1 signal in the globus pallidus, dentate nucleus and pulvinar with an increasing number of contrast administrations. Patient gender, age, and MRI field strength were not associated with changing signal intensity ratios. However, MRI sequence type and vendor significantly impacted some measured signal intensity ratios. Finally, significant differences in the slopes of the ratios were present among patients for multiple locations.

CONCLUSION

Repeated administration of gadopentetate dimeglumine is associated with T1 hyperintense signal in the dentate nucleus, globus pallidus and pulvinar. Detection is significantly affected by MRI sequence type and scanner vendor. Even when accounting for these differences, there are individual differences in the slope of signal intensity change suggesting a patient-level effect influences gadolinium deposition.

Effect of at Least 10 Serial Gadobutrol Administrations on Brain Signal Intensity Ratios on T1-Weighted MRI in Children: A Matched Case-Control Study

BACKGROUND. An association is recognized between linear gadolinium-based contrast agents (GBCAs) and intracranial gadolinium retention in children. The relation between macrocyclic GBCAs and gadolinium retention remains incompletely understood. OBJECTIVE. The purpose of this study was to assess whether 10 or more administrations of the macrocyclic GBCA gadobutrol are associated with increased signal intensity (SI) in the dentate nucleus (DN) and globus pallidus (GP) on unenhanced T1-weighted MRI of children and to explore clinical variables potentially associated with T1 hyperintensity. METHODS. The case group consisted of 25 children (13 boys, 12 girls; mean age, 7 ± 4 years; range, 2-18 years) who underwent at least 10 (mean, 15 ± 6; range, 10-34) contrast-enhanced MRI examinations exclusively with gadobutrol. The control group consisted of 25 age- and sex-matched patients undergoing MRI who had never been exposed to gadolinium. Two observers in consensus using a 3-point scale assessed visual T1 hyperintensity in the DN and GP. One observer placed ROIs on T1-weighted images to mark the DN, GP, middle cerebellar peduncle (MCP), and pulvinar of the thalamus bilaterally to compute mean DN-to-MCP and GP-to-thalamus SI ratios. SI ratios were compared between the macrocyclic GBCA and control groups. In the macrocyclic GBCA group, Pearson correlation analysis was conducted between SI ratios and clinical variables. ROI measurements were repeated by the original reader and an independent reader, and interobserver and intraobserver agreement were computed by means of Lin concordance correlation coefficient (ρ_c). RESULTS. No patient had visual T1 hyperintensity in the DN or GP. No significant difference between the macrocyclic GBCA and control groups was observed for DN-to-MCP SI ratio (0.95 ± 0.05 vs 0.95 ± 0.03; p = .67) or GP-to-thalamus SI ratio (1.05 ± 0.06 vs 1.04 ± 0.06; p = .65). In the macrocyclic GBCA group, no significant correlation was observed between DN-to-MCP SI ratio or GP-to-thalamus SI ratio and age (r = 0.355, p = .08; r = 0.167, p = .42), number of contrast-enhanced MRI examinations (r = 0.247, p = .23; r = 0.203, p = .33), mean time between examinations (r = 0.193, p = .36; r = 0.047, p = .82), or cumulative macrocyclic GBCA dose (r = 0.434, p = .07; r = 0.270, p = .19). Interobserver and intraobserver agreement was substantial for DN-to-MCP SI and GP-to-TH SI ratios (ρ_c = 0.931-0.974). CONCLUSION. Ten or more serial gadobutrol administrations were not associated with T1 hyperintensity in the DN or GP of children. CLINICAL IMPACT. Selection of gadobutrol as an MRI contrast agent may reduce risk of gadolinium retention in children. The findings may help guide practices for GBCA administration to children.

T1 signal intensity in the dentate nucleus after the administration of the macrocyclic gadolinium-based contrast agent gadoterate meglumine: an observational study

INTRODUCTION AND AIMS

Contradictory results have been reported about hyperintensity of the globus pallidus and/or dentate nucleus on unenhanced T1-weighted magnetic resonance (MR) images after exposure to various gadolinium-based contrast agents. This change in signal intensity varies with different gadolinium-based contrast agents. We aimed to determine whether signal intensity in the dentate nucleus is increased in unenhanced T1-weighted images in patients who have undergone multiple studies with the macrocyclic gadolinium-based contrast agent gadoterate meglumine. We thoroughly reviewed the literature to corroborate our results.

MATERIALS AND METHODS

We included patients who had undergone more than 10 MR studies with gadoterate meglumine. We quantitatively analyzed the signal intensity in unenhanced T1-weighted MR images measured in regions of interest placed in the dentate nucleus and the pons, and we calculated the dentate nucleus-to-pons signal intensity ratios and the differences between the ratio in the first MR study and the last MR study. We used t-tests to evaluate whether the differences between the signal intensity ratios were different from 0. We also analyzed the subgroups of patients who had been administered<15 and ≥15 doses of gadoterate meglumine. We used Pearson correlation to determine the relationships between the differences in the signal intensity ratios and the number of doses of gadoterate meglumine administered.

RESULTS

The 54 patients (26 men) had received a mean of 13.8±3.47 doses (range, 10-23 doses). The difference in the dentate nucleus-pons signal intensity ratio between the first and last MR study was -0.0275±0.1917 (not significantly different from 0; p=0.2968) in the entire group, -0.0357±0.2204 (not significantly different from 0; p=0.351 in the patients who had received <15 doses (n=34), and -0.0135±0.1332 (not significantly different from 0; p=0.655) in those who had received ≥15 doses (n=20). Differences in signal intensity ratios did not correlate significantly with the accumulated dose of gadoterate meglumine (P=0.9064; ρ=-0.0164 [95%]).

CONCLUSIONS

Receiving more than 10 doses of gadoterate meglumine was not associated with increased signal intensity in the dentate nucleus.

Updated Clinical Practice Guideline on Use of Gadolinium-Based Contrast Agents in Kidney Disease Issued by the Canadian Association of Radiologists

In 2017, the Canadian Association of Radiologists issued a clinical practice guideline (CPG) regarding the use of gadolinium-based contrast agents (GBCAs) in patients with acute kidney injury (AKI), chronic kidney disease (CKD), or on dialysis due to mounting evidence indicating that nephrogenic systemic fibrosis (NSF) occurs with extreme rarity or not at all when using Group II GBCAs or the Group III GBCA gadoxetic acid (compared to first generation Group I linear GBCAs). One of the goals of the work group was to re-evaluate the CPG after 24 months to determine the effect of more liberal use of GBCA on reported cases of NSF in patients with AKI, CKD Stage 4 or 5 (estimated glomerular filtration rate [eGFR] < 30 mL/min/1.73 m2), or those that are dialysis-dependent. A comprehensive review of the literature was conducted by a subcommittee of the initial CPG panel between the dates of January 1, 2017-December 31, 2018 to identify new unconfounded cases of NSF linked to Group II or Group III GBCAs and an updated CPG developed. To our knowledge, when using a Group II or Group III GBCA between 2017-2018, only a single unconfounded case report of a fibrosing dermopathy has been reported in a patient who received gadobenate dimeglumine with Stage 2 CKD. No other unconfounded cases of NSF have been reported with Group II or III agents in during this timeframe. The subcommittee concluded that the main recommendations from the 2017 CPG should remain unaltered, but agreed that screening for renal disease in the outpatient setting is no longer justifiable, cost-effective or recommended. Patients on hemodialysis (HD) should, however, be identified prior to GBCA administration to arrange timely HD to optimize gadolinium clearance, although there remains no evidence that HD reduces the risk of NSF. When administering Group II or III GBCAs to patients with AKI, on dialysis or with severe CKD, informed consent relating to NSF is also no longer explicitly recommended.

Update on Gadolinium-Based Contrast Agent-Enhanced Imaging in the Genitourinary System

OBJECTIVE. The purpose of this article is to review gadolinium-based contrast agent (GBCA)-enhanced MRI applications in the genitourinary system. CONCLUSION. Nephrogenic systemic fibrosis is rare or nonexistent with standard dosing of group II GBCAs. Gadolinium retention, cost, and examination times are emerging considerations affecting GBCA use. GBCA is unnecessary to diagnose adrenal adenomas, simple cysts, and some Bosniak category II cysts; however, it is required to determine solid or septal renal mass enhancement. Biparametric prostate MRI requires high-quality and reproducible DWI; therefore, dynamic contrast-enhanced MRI remains valuable in selected prostate MRI examinations.

Standardized assessment of the signal intensity increase on unenhanced T1-weighted images in the brain: the European Gadolinium Retention Evaluation Consortium (GREC) Task Force position statement

After the initial report in 2014 on T1-weighted (T1w) hyperintensity of deep brain nuclei following serial injections of linear gadolinium-based contrast agents (GBCAs), a multitude of studies on the potential of the marketed GBCAs to cause T1w hyperintensity in the brain have been published. The vast majority of these studies found a signal intensity (SI) increase for linear GBCAs in the brain-first and foremost in the dentate nucleus-while no SI increase was found for macrocyclic GBCAs. However, the scientific debate about this finding is kept alive by the fact that SI differences do not unequivocally represent the amount of gadolinium retained. Since the study design of the SI measurement in various brain structures is relatively simple, MRI studies investigating gadolinium-dependent T1w hyperintensity are currently conducted at multiple institutions worldwide. However, methodological mistakes may result in flawed conclusions. In this position statement, we assess the methodological basis of the published retrospective studies and define quality standards for future studies to give guidance to the scientific community and to help identify studies with potentially flawed methodology and misleading results. KEY POINTS: • A multitude of studies has been published on the potential of the marketed GBCAs to cause T1w hyperintensity in the brain. • The gadolinium-dependent T1w hyperintensity in the brain depends on patient's history, types of GBCAs used (i.e., linear vs. macrocyclic GBCAs) and MR imaging setup and protocols. • Quality standards for the design of future studies are needed to standardize methodology and avoid potentially misleading results from retrospective studies.

Gadolinium Deposition in Brain: Current Scientific Evidence and Future Perspectives

In the past 4 years, many publications described a concentration-dependent deposition of gadolinium in the brain both in adults and children, seen as high signal intensities in the globus pallidus and dentate nucleus on unenhanced T1-weighted images. Postmortem human or animal studies have validated gadolinium deposition in these T1-hyperintensity areas, raising new concerns on the safety of gadolinium-based contrast agents (GBCAs). Residual gadolinium is deposited not only in brain, but also in extracranial tissues such as liver, skin, and bone. This review summarizes the current evidence on gadolinium deposition in the human and animal bodies, evaluates the effects of different types of GBCAs on the gadolinium deposition, introduces the possible entrance or clearance mechanism of the gadolinium and potential side effects that may be related to the gadolinium deposition on human or animals, and puts forward some suggestions for further research.

Intravoxel incoherent motion MRI in neurological and cerebrovascular diseases

Intravoxel Incoherent Motion (IVIM) is a recently rediscovered noninvasive magnetic resonance imaging (MRI) method based on diffusion-weighted imaging. It enables the separation of the intravoxel signal into diffusion due to Brownian motion and perfusion-related contributions and provides important information on microperfusion in the tissue and therefore it is a promising tool for applications in neurological and neurovascular diseases. This review focuses on the basic principles and outputs of IVIM and details it major applications in the brain, such as stroke, tumor, and cerebral small vessel disease. A bi-exponential model that considers two different compartments, namely capillaries, and medium-sized vessels, has been frequently used for the description of the IVIM signal and may be important in those clinical applications cited before. Moreover, the combination of IVIM and arterial spin labeling MRI enables the estimation of water permeability across the blood-brain barrier (BBB), suggesting a potential imaging biomarker for disrupted-BBB diseases.