An overview of magnesium-based implants in orthopaedics and a prospect of its application in spine fusion

Due to matching biomechanical properties and significant biological activity, Mg-based implants present great potential in orthopedic applications. In recent years, the biocompatibility and therapeutic effect of magnesium-based implants have been widely investigated in trauma repair. In contrast, the R&D work of Mg-based implants in spinal fusion is still limited. This review firstly introduced the general background for Mg-based implants. Secondly, the mechanical properties and degradation behaviors of Mg and its traditional and novel alloys were reviewed. Then, different surface modification techniques of Mg-based implants were described. Thirdly, this review comprehensively summarized the biological pathways of Mg degradation to promote bone formation in neuro-musculoskeletal circuit, angiogenesis with H-type vessel formation, osteogenesis with osteoblasts activation and chondrocyte ossification as an integrated system. Fourthly, this review followed the translation process of Mg-based implants via updating the preclinical studies in fracture fixation, sports trauma repair and reconstruction, and bone distraction for large bone defect. Furthermore, the pilot clinical studies were involved to demonstrate the reliable clinical safety and satisfactory bioactive effects of Mg-based implants in bone formation. Finally, this review introduced the background of spine fusion surgeryand the challenges of biological matching cage development. At last, this review prospected the translation potential of a hybrid Mg-PEEK spine fusion cage design.

Efficient segmentation of active and inactive plaques in FLAIR-images using DeepLabV3Plus SE with efficientnetb0 backbone in multiple sclerosis

This research paper introduces an efficient approach for the segmentation of active and inactive plaques within Fluid-attenuated inversion recovery (FLAIR) images, employing a convolutional neural network (CNN) model known as DeepLabV3Plus SE with the EfficientNetB0 backbone in Multiple sclerosis (MS), and demonstrates its superior performance compared to other CNN architectures. The study encompasses various critical components, including dataset pre-processing techniques, the utilization of the Squeeze and Excitation Network (SE-Block), and the atrous spatial separable pyramid Block to enhance segmentation capabilities. Detailed descriptions of pre-processing procedures, such as removing the cranial bone segment, image resizing, and normalization, are provided. This study analyzed a cross-sectional cohort of 100 MS patients with active brain plaques, examining 5000 MRI slices. After filtering, 1500 slices were utilized for labeling and deep learning. The training process adopts the dice coefficient as the loss function and utilizes Adam optimization. The study evaluated the model's performance using multiple metrics, including intersection over union (IOU), Dice Score, Precision, Recall, and F1-Score, and offers a comparative analysis with other CNN architectures. Results demonstrate the superior segmentation ability of the proposed model, as evidenced by an IOU of 69.87, Dice Score of 76.24, Precision of 88.89, Recall of 73.52, and F1-Score of 80.47 for the DeepLabV3+SE_EfficientNetB0 model. This research contributes to the advancement of plaque segmentation in FLAIR images and offers a compelling approach with substantial potential for medical image analysis and diagnosis.

Effective removal of gadolinium with hemodialysis in a dog with severe acute on chronic kidney injury

OBJECTIVE

To describe the use of intermittent hemodialysis (IHD) to remove gadolinium (28.1 mg/kg dose) in a dog with severe kidney disease.

CASE SUMMARY

A 12-year-old neutered female Yorkshire Terrier presented with severe acute-on-chronic kidney injury and concurrent neurological signs. The dog received extracorporeal therapy as part of management. Uremia improved after hemodialysis, but central nervous system signs persisted; therefore, a contrast-enhanced magnetic resonance imaging was performed, immediately followed by IHD. Two IHD treatments with a low-flux dialyzer were performed 1.5 and 25.75 hours after administration of gadolinium, with almost complete removal of gadolinium. More than 96% of gadolinium was removed with a single treatment.

NEW OR UNIQUE INFORMATION PROVIDED

Extracorporeal therapy is effective at removing gadolinium-based chelated contrast agents and could be considered if magnetic resonance imaging is indicated in a patient with substantial kidney impairment. Alternatively, newer contrast agents that have been deemed safer in this patient population could be used.

Gadolinium-Based Contrast Agents and Free Gadolinium Inhibit Differentiation and Activity of Bone Cell Lineages

OBJECTIVES

Administration of gadolinium-based contrast agents (GBCA) in magnetic resonance imaging results in the long-term retention of gadolinium (Gd) in tissues and organs, including the bone, and may affect their function and metabolism. This study aims to investigate the effects of Gd and GBCA on the proliferation/survival, differentiation, and function of bone cell lineages.

MATERIALS AND METHODS

Primary murine osteoblasts (OB) and osteoclast progenitor cells (OPC) isolated from C57BL/6J mice were used to test the effects of Gd 3+ (12.5-100 μM) and GBCA (100-2000 μM). Cultures were supplemented with the nonionic linear Gd-DTPA-BMA (gadodiamide), ionic linear Gd-DTPA (gadopentetic acid), and macrocyclic Gd-DOTA (gadoteric acid). Cell viability and differentiation were analyzed on days 4-6 of the culture. To assess the resorptive activity of osteoclasts, the cells were grown in OPC cultures and were seeded onto layers of amorphous calcium phosphate with incorporated Gd.

RESULTS

Gd 3+ did not affect OB viability, but differentiation was reduced dose-dependently up to 72.4% ± 6.2%-73.0% ± 13.2% (average ± SD) at 100 μM Gd 3+ on days 4-6 of culture as compared with unexposed controls ( P < 0.001). Exposure to GBCA had minor effects on OB viability with a dose-dependent reduction up to 23.3% ± 10.2% for Gd-DTPA-BMA at 2000 μM on day 5 ( P < 0.001). In contrast, all 3 GBCA caused a dose-dependent reduction of differentiation up to 88.3% ± 5.2% for Gd-DTPA-BMA, 49.8% ± 16.0% for Gd-DTPA, and 23.1% ± 8.7% for Gd-DOTA at 2000 μM on day 5 ( P < 0.001). In cultures of OPC, cell viability was not affected by Gd 3+ , whereas differentiation was decreased by 45.3% ± 9.8%-48.5% ± 15.8% at 100 μM Gd 3+ on days 4-6 ( P < 0.05). Exposure of OPC to GBCA resulted in a dose-dependent increase in cell viability of up to 34.1% ± 11.4% at 2000 μM on day 5 of culture ( P < 0.001). However, differentiation of OPC cultures was reduced on day 5 by 24.2% ± 9.4% for Gd-DTPA-BMA, 47.1% ± 14.0% for Gd-DTPA, and 38.2% ± 10.0% for Gd-DOTA ( P < 0.001). The dissolution of amorphous calcium phosphate by mature osteoclasts was reduced by 36.3% ± 5.3% upon incorporation of 4.3% Gd/Ca wt/wt ( P < 0.001).

CONCLUSIONS

Gadolinium and GBCA inhibit differentiation and activity of bone cell lineages in vitro. Thus, Gd retention in bone tissue could potentially impair the physiological regulation of bone turnover on a cellular level, leading to pathological changes in bone metabolism.

Toxic Effects of Rare Earth Elements on Human Health: A Review

Rare earth elements (REEs) are a new type of material resource which have attracted significant attention in recent years. REEs have emerged as essential metals in modern-day technology due to their unique functions. The long-term, large-scale mining and utilization of rare earths has caused serious environmental pollution and constitutes a global health issue, which has raised concerns regarding the safety of human health. However, the toxicity profile of suspended particulate matter in REEs in the environment, which interacts with the human body, remains largely unknown. Studies have shown that REEs can enter the human body through a variety of pathways, leading to a variety of organ and system dysfunctions through changes in genetics, epigenetics, and signaling pathways. Through an extensive literature search and critical analysis, we provide a comprehensive overview of the available evidence, identify knowledge gaps, and make recommendations for future research directions.

Gadolinium Contrast Agent Deposition in Children

Over the past few years, a large number of studies have evidenced increased signal intensity in the deep brain nuclei on unenhanced T1-MRI images achieved by the application of gadolinium-based contrast agents (GBCAs). The deposition of gadolinium in the brain, bone, and other tissues following administration of GBCAs has also been confirmed in histological studies in rodents and in necropsy studies in adults and children. Given the distinct physiological characteristics of children, this review focuses on examining the current research on gadolinium deposition in children, particularly studies utilizing novel methods and technologies. Furthermore, the article compares safety research findings of linear GBCAs and macrocyclic GBCAs in children, with the aim of offering clinicians practical guidance based on the most recent research outcomes. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 2.

Elemental Bioimaging of Sheep Bone and Articular Cartilage After Single Application of Gadolinium-Based Contrast Agents

BACKGROUND

Gadolinium-based contrast agents (GBCAs) are applied to enhance magnetic resonance imaging. Gadolinium (Gd), a rare earth metal, is used in a chelated form when administered as GBCA to patients. There is an ongoing scientific debate about the clinical significance of Gd retention in tissues after administration of GBCAs. It is known that bone serves as Gd reservoir, but only sparse information on localization of Gd in bone is available.

PURPOSE

The aim of this study was to compare Gd tissue concentration and spatial distribution in femoral epiphysis and diaphysis 10 weeks after single-dose injection of linear and macrocyclic GBCAs in a large animal model.

MATERIALS AND METHODS

In this prospective animal study, Swiss-Alpine sheep (n = 36; age range, 4-10 years) received a single injection (0.1 mmol/kg) of macrocyclic (gadobutrol, gadoteridol, and gadoterate meglumine), linear (gadodiamide and gadobenate dimeglumine) GBCAs, or saline. Ten weeks after injection, sheep were killed, and femur heads and shafts were harvested. Gadolinium spatial distribution was determined in 1 sample of each treatment group by laser ablation-inductively coupled plasma-mass spectrometry. All bone specimens were analyzed histopathologically.

RESULTS

Injection of GBCAs in female Swiss-Alpine sheep (n = 36) resulted in Gd localization at the endosteal and periosteal surface and in a subset of GBCAs additionally at the cement lines and the bone cartilage junction. No histopathological alterations were observed in the investigated tissue specimens.

CONCLUSIONS

Ten weeks after single injection of a clinically relevant dose in adult sheep, both linear species of GBCA resulted in considerably higher accumulation than macrocyclic GBCAs. Gadolinium deposits were restricted to distinct bone and cartilage compartments, such as in bone linings, cement lines, and bone cartilage junctions. Tissue histology remained unaffected.

Contrast Media-driven Anthropogenic Gadolinium: Knowns and Unknowns

Gadolinium-based contrast agents (GBCAs) have augmented the capabilities of MRI, which has led to their widespread and increasing use in radiology practice. GBCAs are introduced into the environment through disposal of unused product and elimination after intravenous injection, both primarily via liquid dispersion into the environment. This human introduction of gadolinium into the environment, referred to as anthropogenic gadolinium, is associated with the detection of gadolinium in water systems, raising concerns for potential adverse impact and prompting certain mitigation actions. This article summarizes the existing knowledge and problem scope, conveys the relevant underlying chemical principles of chelate dissociation, and offers an inferred perspective that the magnitude of the problem is most unlikely to cause human harm. The merits and limitations regarding possible mitigation tactics, such as collecting urine after GBCA administration, use of lower-dose high-relaxivity macrocyclic GBCAs, and the option for virtual contrast-enhanced examinations, will be discussed. Finally, the potential for monitoring gadolinium uptake in bone will be presented, and recommendations for future research will be offered. © RSNA, 2024 See also the article by Ibrahim et al in this issue. See also the article by McKee et al in this issue.

Development and Characterization of Gadolinium and Copper Reinforced Bioactive Glass: An In Vitro Study

INTRODUCTION

Bioactive glass, an innovative alloplastic material utilizing a matrix of silica particles combined with calcium and phosphorus, has been widely employed for the regeneration of bony defects due to its bone-forming capabilities and biocompatibility. Nevertheless, it comes with several drawbacks, including a slow degradation rate, low mechanical strength, and susceptibility to fractures. To address these issues, the present research was done to develop and characterize a novel bioactive glass incorporating gadolinium (Gd) and copper (Cu).

METHODS

The bioactive glass doped with Gd and Cu were synthesized and subjected to characterization through X-ray diffraction (XRD), scanning electron microscopy (SEM), and attenuated total reflectance-infrared (ATR-IR) analysis.

RESULTS

The bioactive glass, enriched with Gd and Cu, underwent analysis using ATR-IR spectroscopy, XRD, and SEM. ATR-IR revealed characteristic silicate bands, while SEM indicated the presence of particles larger than 4 μm. XRD analysis identified the formation of Na2Ca4(PO4)2SiO4 (Silicorhenatite), Na2Ca2Si3O9 (Combeite), and wollastonite (calcium inosilicate mineral; CaSiO3). The crystalline nature of these compounds contributed to the favorable mechanical properties of the bioactive glass.

CONCLUSION

In summary, the creation of the innovative Gd-Cu-incorporated bioactive glass demonstrates favorable mechanical characteristics, suggesting significant promise for augmenting bone regeneration.

Preclinical Safety Assessment of Gadopiclenol: A High-Relaxivity Macrocyclic Gadolinium-Based MRI Contrast Agent

OBJECTIVE

Gadopiclenol is a new high-relaxivity macrocyclic gadolinium-based contrast agent for magnetic resonance imaging of the central nervous system and other body regions. The product has been approved by US Food and Drug Administration and is currently being evaluated by European Medicines Agency. For risk assessment of the single diagnostic use in humans, the safety profile of gadopiclenol was evaluated with a series of preclinical studies.

MATERIALS AND METHODS

With exception of dose-ranging studies, all safety pharmacology and toxicology studies were performed in compliance with Good Laboratory Practice principles. Safety pharmacology studies were conducted to assess potential effects on cardiovascular (in vitro and in dogs), respiratory (in rats and guinea pigs), neurological (in rats), and renal endpoints (in rats). Toxicology studies were also performed to investigate acute toxicity (in rats and mice), extended single-dose (in rats and dogs) and repeated-dose toxicity (in rats and dogs), reproductive (in rats), developmental (in rats and rabbits) and juvenile toxicity (in rats), as well as genotoxicity (in vitro and in rats), local tolerance (in rabbits), potential immediate hypersensitivity (in guinea pigs), and potential tissue retention of gadolinium (in rats).

RESULTS

Safety pharmacology studies conducted at high intravenous (IV) doses showed a satisfactory tolerance of gadopiclenol in the main body systems. After either single or repeated IV dosing (14 and 28 days) in rats and dogs, gadopiclenol was well tolerated even at high doses. The no-observed-adverse-effect level values (ie, the highest experimental dose without adverse effects) representing between 8 times in rats and 44 times in dogs (based on the exposure), the exposure achieved in humans at the intended diagnostic dose, provide a high safety margin. No or only minor and reversible effects on body weight, food consumption, clinical signs, clinical pathology parameters, or histology were observed at the highest doses. The main histological finding consists in renal tubular vacuolations (exacerbated after repeated exposure), which supports a well-known finding for this class of compounds that has no physiological consequence on kidney function. Reproductive toxicity studies showed no evidence of effects on reproductive performance, fertility, perinatal and postnatal development in rats, or reproductive development in rats or rabbits. The safety profile of gadopiclenol in juvenile rats was satisfactory like in adults. Gadopiclenol was not genotoxic in vitro in the Ames test, a mouse lymphoma assay, and a rat in vivo micronucleus test. There were no signs of local intolerance at the injection site after IV and intra-arterial administration in rabbits. However, because of minor signs of intolerance after perivenous administration, misadministration must be avoided. Gadopiclenol exhibited no signs of potential to induce immediate hypersensitivity in guinea pigs.

CONCLUSIONS

High safety margins were observed between the single diagnostic dose of 0.05 mmol/kg in humans and the doses showing effects in animal studies. Gadopiclenol is, therefore, well tolerated in various species (mice, rats, dogs, rabbits, and guinea pigs). All observed preclinical data support the clinical approval.

MRI Gadolinium-Based Contrast Media: Meeting Radiological, Clinical, and Environmental Needs

Gadolinium-based contrast agents (GBCAs) are routinely used in magnetic resonance imaging (MRI). They are essential for choosing the most appropriate medical or surgical strategy for patients with serious pathologies, particularly in oncologic, inflammatory, and cardiovascular diseases. However, GBCAs have been associated with an increased risk of nephrogenic systemic fibrosis in patients with renal failure, as well as the possibility of deposition in the brain, bones, and other organs, even in patients with normal renal function. Research is underway to reduce the quantity of gadolinium injected, without compromising image quality and diagnosis. The next generation of GBCAs will enable a reduction in the gadolinium dose administered. Gadopiclenol is the first of this new generation of GBCAs, with high relaxivity, thus having the potential to reduce the gadolinium dose while maintaining good in vivo stability due to its macrocyclic structure. High-stability and high-relaxivity GBCAs will be one of the solutions for reducing the dose of gadolinium to be administered in clinical practice, while the development of new technologies, including optimization of MRI acquisitions, new contrast mechanisms, and artificial intelligence may help reduce the need for GBCAs. Future solutions may involve a combination of next-generation GBCAs and image-processing techniques to optimize diagnosis and treatment planning while minimizing exposure to gadolinium. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 3.

Ten years of gadolinium retention and deposition: ESMRMB-GREC looks backward and forward

In 2014, for the first time, visible hyperintensities on unenhanced T1-weighted images in the nucleus dentatus and globus pallidus of the brain were associated with previous Gadolinium-based contrast agent (GBCA) injections and gadolinium deposition in patients with normal renal function. This led to a frenzy of retrospective studies with varying methodologies that the European Society of Magnetic Resonance in Medicine and Biology Gadolinium Research and Educational Committee (ESMRMB-GREC) summarised in 2019. Now, after 10 years, the members of the ESMRMB-GREC look backward and forward and review the current state of knowledge of gadolinium retention and deposition. CLINICAL RELEVANCE STATEMENT: Gadolinium deposition is associated with the use of linear GBCA but no clinical symptoms have been associated with gadolinium deposition. KEY POINTS : • Traces of Gadolinium-based contrast agent-derived gadolinium can be retained in multiple organs for a prolonged time. • Gadolinium deposition is associated with the use of linear Gadolinium-based contrast agents. • No clinical symptoms have been associated with gadolinium deposition.

Evaluation of gadolinium deposition in cortical bone using three-dimensional ultrashort echo time quantitative susceptibility mapping: A preliminary study

The aim of the current study was to investigate the feasibility of three-dimensional ultrashort echo time quantitative susceptibility mapping (3D UTE-QSM) for the assessment of gadolinium (Gd) deposition in cortical bone. To this end, 40 tibial bovine cortical bone specimens were divided into five groups then soaked in phosphate-buffered saline (PBS) solutions with five different Gd concentrations of 0, 0.4, 0.8, 1.2, and 1.6 mmol/L for 48 h. Additionally, eight rabbits were randomly allocated into three groups, consisting of a normal-dose macrocyclic gadolinium-based contrast agent (GBCA) group (n = 3), a high-dose macrocyclic GBCA group (n = 3), and a control group (n = 2). All bovine and rabbit tibial bone samples underwent magnetic resonance imaging (MRI) on a 3-T clinical MR system. A 3D UTE-Cones sequence was utilized to acquire images with five different echo times (i.e., 0.032, 0.2, 0.4, 0.8, and 1.2 ms). The UTE images were subsequently processed with the morphology-enabled dipole inversion algorithm to yield a susceptibility map. The average susceptibility was calculated in three regions of interest in the middle of each specimen, and the Pearson's correlation between the estimated susceptibility and Gd concentration was calculated. The bone samples soaked in PBS with higher Gd concentrations exhibited elevated susceptibility values. A mean susceptibility value of -2.47 ± 0.23 ppm was observed for bovine bone soaked in regular PBS, while the mean QSM value increased to -1.75 ± 0.24 ppm for bone soaked in PBS with the highest Gd concentration of 1.6 mmol/L. A strong positive correlation was observed between Gd concentrations and QSM values. The mean susceptibility values of rabbit tibial specimens in the control group, normal-dose GBCA group, and high-dose GBCA group were -4.11 ± 1.52, -3.85 ± 1.33, and -3.39 ± 1.35 ppm, respectively. In conclusion, a significant linear correlation between Gd in cortical bone and QSM values was observed. The preliminary results suggest that 3D UTE-QSM may provide sensitive noninvasive assessment of Gd deposition in cortical bone.

Reliability of signal intensity in the basal ganglia on non-contrast T1-weighted MR scans after repetitive application of a gadolinium-based contrast agent in pediatric neuro-oncology patients

PURPOSE

To evaluate the reliability of signal intensity (SI) changes in the basal ganglia as a supposed indicator of gadolinium deposition in the brain after repetitive application of gadolinium-based contrast agents (GBCAs) in a pediatric neuro-oncological collective.

METHODS

One hundred and eight neuropediatric patients (54 male, 54 female, 0-17 years old), with repetitive GBCA-enhanced cranial MRIs between 2003 and 2017, were retrospectively analyzed. Two radiologists measured SI in the nucleus dentatus (ND), globus pallidus (GP), thalamus (T), and the pons (P). The NDP and GPT ratio were calculated. An intraclass correlation coefficient, and multiple linear regressions with subsequent stepwise backward variable selection were performed to evaluate the influence of gender, patient's age at the first MRI, time interval between the first and last MRI, linear or macrocyclic GBCAs, residual pathology, treatments, and magnet field strengths.

RESULTS

The inter-reader agreement was good for GPT and NDP in the whole collective (ICC = 0.837 and ICC = 0.793) and for children >2 years of age (ICC = 0.874 and ICC = 0.790), but poor to moderate for children ≤2 years of age (ICC = 0.397 and ICC = 0.748). The intra-reader agreement was good (ICC = 0.910 and ICC = 0.882). An SI increase was only observed for both readers in GPT (p = 0.003, or p < 0.001). None of the considered cofactors showed a consistent effect on SI changes for either readers or regions.

CONCLUSION

Measurements of SI changes in the basal ganglia are not a reliable parameter with which to evaluate or estimate gadolinium deposition in the brain or to identify suspicious influential factors after repeated GBCA applications.

Probing the dynamic behaviour and magnetic identification of seven coordinated Mn(II) complexes: a combined AIMD and multi-reference approach

We present an in-depth solution phase dynamics of rare seven coordinated pentagonal bipyramidal Mn(II) complexes, together with their binding affinity anticipated using ab initio molecular dynamics (AIMD) simulations and density functional theory (DFT). Moreover, the simulations at different temperatures (25 °C and 90 °C) interpret the rigidity and stability of the ligands with Mn(II) ions. An intuitive approach for modulating the easy plane magnetic anisotropy of the mononuclear Mn(II) complex has been revealed by this work. In this regard, we have performed an extensive theoretical study based on the ab initio CASSCF/NEVPT2 method, exhibiting the presence of an easy plane magnetic anisotropy with a positive value of axial zero-field splitting (ZFS) parameter D. The complex's magnetic properties and electronic relaxation reveal that the rhombic ZFS term (E) can be modulated as the symmetry around the Mn(II) ion varies. The magnitude of the D-value increased with a more symmetrical equatorial ligand as found in the order of [Mn(pydpa)(H2O)] > [Mn(cbda)(H2O)]- > [Mn(dpaaa)(H2O)]- > [Mn(dpasam)(H2O)]-. Furthermore, we found that substituting the equatorial oxygen atom with heavier S and Se-donor atoms switches the sign of magnetic anisotropy for the Mn(II) complexes. The magnitude of the D-value increased when the energy levels of the ground state (GS) and the first excited state (ES) decreased. The observed magneto-structural correlation reveals that shortening the distance of the axial water molecule (Mn-O(w)) increases the D-value by an order of magnitude for the symmetrical [Mn(pydpa)(H2O)] complex. Overall, the combined analysis of solution phase dynamics of Mn(II) complexes and their magnetic characterization opens up new avenues in coordination chemistry, molecular magnetism, spin-crossover materials, and catalysis.

In Vitro Studies Regarding the Effect of Cellulose Acetate-Based Composite Coatings on the Functional Properties of the Biodegradable Mg3Nd Alloys

Magnesium (Mg) alloys are adequate materials for orthopedic and maxilo-facial implants due to their biocompatibility, good mechanical properties closely related to the hard tissues, and processability. Their main drawbacks are the high-speed corrosion process and hydrogen release. In order to improve corrosion and mechanical properties, the Mg matrix can be strengthened through alloying elements with high temperature-dependent solubility materials. Rare earth elements (RE) contribute to mechanical properties and degradation improvement. Another possibility to reduce the corrosion rate of Mg-based alloys was demonstrated to be the different types of coatings (bioceramics, polymers, and composites) applied on their surface. The present investigation is related to the coating of two Mg-based alloys from the system Mg3Nd (Mg-Nd-Y-Zr-Zn) with polymeric-based composite coatings made from cellulose acetate (CA) combined with two fillers, respectively hydroxyapatite (HAp) and Mg particles. The main functions of the coatings are to reduce the biodegradation rate and to modify the surface properties in order to increase osteointegration. Firstly, the microstructural features of the experimental Mg3Nd alloys were revealed by optical microscopy and scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy. Apart from the surface morphology revealed by SEM, the roughness and wettability of all experimental samples were evaluated. The corrosion behavior of the uncoated and coated samples of both Mg3Nd alloys was investigated by immersion testing and electrochemical testing using Simulated Body Fluid as the medium. The complex in vitro research performed highlights that the composite coating based on CA with HAp particles exhibited the best protective effect for both Mg3Nd alloys.

Amide proton transfer weighted MRI in differential diagnosis of ovarian masses with cystic components: A preliminary study

RATIONALE AND OBJECTIVES

To evaluate the performance of three-dimensional (3D) amide proton transfer-weighted (APTw) MRI in the differentiation between benign and malignant ovarian masses based on single-slice and all-slice analysis of cystic regions.

MATERIALS AND METHODS

Patients were consecutively recruited and underwent conventional pelvic MRI and APTw MRI. Two radiologists independently assessed ovarian masses blinded to the histopathological results. Three APTw SI values were generated from the cystic regions of the masses: (1) APTw SI of a single representative slice (RS); (2) average (AVE) of APTw SIs of all slices of the mass; (3) area-weighted (AW) average of APTw SIs of all slices of the mass. O-RADS MRI score of each mass was reported. Independent sample t-test and receiver operating characteristic (ROC) curve analysis were performed for comparison. Inter- and intra-observer reliability were assessed by the intraclass correlation coefficient (ICC) and quadratic kappa coefficient.

RESULTS

46 ovarian masses were included for final analysis. The three APTw SI values were higher in cystic regions of malignant ovarian masses compared with benign lesions (p<0.0001). ROC curve analysis showed no significant difference in diagnostic performance among three APTw SI values and the O-RADS MRI score (AUC: RS-APTw SI, 0.930; AVE-APTw SI, 0.927; AW-APTw SI, 0.935; O-RADS score, 0.937).

CONCLUSIONS

APTw MRI may be used as a noninvasive tool for the differentiation of benign and malignant ovarian masses based on the analysis of the cystic regions.

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.

Gadolinium during human pregnancy following administration of gadolinium chelate before pregnancy

Gadolinium (Gd), a toxic rare earth element, has been shown to dissociate from chelating agents and bioaccumulate within tissues, raising concerns about the possibility of their remobilization during pregnancy with subsequent free Gd exposures to developing fetuses. Gd chelates are among the most commonly used magnetic resonance imaging (MRI) contrast agents. This investigation was undertaken after the detection of elevated Gd (800-1000× higher than the usual rare earth element levels) in preliminary unpublished studies from the placentae of subjects in the NIH ECHO/UPSIDE Rochester Cohort Study and unpublished studies from placentae analyzed in formalin-fixed placental specimens from Surgical Pathology at the University of Rochester. Fifteen pregnancies with elevated Gd were studied (12 first pregnancies and 3 second pregnancies). Maternal bloods were collected from all three trimesters, maternal, and cord (fetal) bloods at delivery as well as placental tissue. Breastmilk was also collected from selected mothers. It was determined that Gd was present in maternal bloods from all three trimesters, and in cord bloods and breastmilk in both first and second pregnancies. These results emphasize the need to fully appreciate the implications of pre-pregnancy exposure to Gd chelates and its potential effects on maternal and fetal health.

Gadolinium-based contrast agents suppress adipocyte differentiation in 3T3-L1 cells

Gadolinium-based contrast agents (GBCAs) are widely used in magnetic resonance imaging (MRI) to improve the sensitivity and enhance diagnostic performance. GBCAs are mostly eliminated from the body through the kidney after administration; however small amounts of gadolinium are retained in the brain and other tissues. Although there is increasing concern about the adverse health effects of gadolinium, the cellular effects of GBCAs remains poorly understood. Here, we elucidated the potential cytotoxicity of the GBCAs Omniscan and Gadovist in 12 different cell lines, especially 3T3-L1 adipocyte cell line. Omniscan and Gadovist treatments significantly increased intracellular gadolinium levels in 3T3-L1 cells in a time- and dose-dependent manner. Additionally, Omniscan and Gadovist treatments downregulated the expression of adipocyte differentiation markers, including peroxisome proliferator-activated receptor γ (PPARG), adiponectin (ADIPOQ), and fatty acid-binding protein (FABP4), in 3T3-L1 cells, especially during early differentiation (day 0-2). Moreover, histological analysis using Oil red O staining showed that gadolinium chloride (GdCl₃) treatment suppressed lipid droplet accumulation and the expression of adipocyte differentiation markers. Overall, the results showed that Omniscan and Gadovist treatment suppressed adipocyte differentiation in 3T3-L1 cells, contributing to the understanding of the potential toxic effects of GBCA exposure.

Intracerebral gadolinium deposition following blood-brain barrier disturbance in two different mouse models

To evaluate the influence of the blood-brain barrier on neuronal gadolinium deposition in a mouse model after multiple intravenous applications of the linear contrast agent gadodiamide. The prospective study held 54 mice divided into three groups: healthy mice (A), mice with iatrogenic induced disturbance of the blood-brain barrier by glioblastoma (B) or cerebral infarction (C). In each group 9 animals received 10 iv-injections of gadodiamide (1.2 mmol/kg) every 48 h followed by plain T1-weighted brain MRI. A final MRI was performed 5 days after the last contrast injection. Remaining mice underwent MRI in the same time intervals without contrast application (control group). Signal intensities of thalamus, pallidum, pons, dentate nucleus, and globus pallidus-to-thalamus and dentate nucleus-to-pons ratios, were determined. Gadodiamide complex and total gadolinium amount were quantified after the last MR examination via LC-MS/MS and ICP-MS. Dentate nucleus-to-pons and globus pallidus-to-thalamus SI ratios showed no significant increase over time within all mice groups receiving gadodiamide, as well as compared to the control groups at last MR examination. Comparing healthy mice with group B and C after repetitive contrast administration, a significant SI increase could only be detected for glioblastoma mice in globus pallidus-to-thalamus ratio (p = 0.033), infarction mice showed no significant SI alteration. Tissue analysis revealed significantly higher gadolinium levels in glioblastoma group compared to healthy (p = 0.013) and infarction mice (p = 0.029). Multiple application of the linear contrast agent gadodiamide leads to cerebral gadolinium deposition without imaging correlate in MRI.

Elemental Imaging of Long-term Gadolinium Retention in Rodent Femur

Background The use of gadolinium-based contrast agents (GBCAs) is linked to gadolinium retention in the skeleton of healthy individuals. The mechanism of gadolinium incorporation into bone tissue is not fully understood and requires spatially resolved analysis to locate the gadolinium. Purpose To compare the quantitative distribution of gadolinium retained over time in rodent femur following the administration of gadodiamide and gadobutrol at three different time points. Materials and Methods In this animal study conducted between May 2018 and April 2020, 108 9-week-old healthy rats were repeatedly injected with either gadodiamide, gadobutrol, or saline solution and were killed 1, 3, or 12 months after the last injection. The femurs of six female and six male rats per each group and time point were collected. Quantitative elemental imaging of gadolinium in longitudinal thin sections was performed on one sample per sex with use of laser ablation inductively coupled plasma mass spectrometry (ICP-MS). Gadolinium concentration was determined with use of ICP-MS on the samples of all animals (six per group). Mann-Whitney U tests were applied on pairwise comparisons to determine potential sex effect and GBCA effect on gadolinium concentrations. Results The highest gadolinium retention was observed in the gadodiamide group (concentration, 97-200 nmol · g^-1), exceeding the mean concentration in the gadobutrol group (6.5-17 nmol · g^-1). However, the gadolinium distribution pattern was similar for both contrast agents, showing prominent gadolinium retention at endosteal surfaces, in the bone marrow, and in small tissue pores. Gadolinium distribution in cortical bone changed over time, initially showing a thin rim of higher concentration close to the periosteum, which appeared to grow wider and move toward the interior of the femur over 1 year. Conclusion For both gadolinium-based contrast agents, gadolinium retention in rat bone was initially located close to the periosteum and bone cavities and changed with bone remodeling processes. The relevance to long-term storage of gadolinium in humans remains to be determined. © RSNA, 2022 Online supplemental material is available for this article.

Comparison of trace element concentrations in paired formalin-fixed paraffin-embedded and frozen human placentae

INTRODUCTION

There is increasing interest in measuring metals concentrations in human placentas to better understand physiology, disease, and toxic and diagnostic exposures. For these purposes, formalin-fixed paraffin embedded (FFPE) tissues obtained at clinical pathology examination represent a valuable potential store of well-characterized tissues for analysis. However, the limited data that exist comparing metal concentrations in FFPE tissue to recently collected frozen tissues paints a confusing picture, and there is no published data directly comparing frozen and FFPE placental villus tissues.

METHODS

Paired samples of fresh frozen and FFPE tissue from 22 rapidly processed human singleton placentae were weighed and digested using standard clean laboratory procedures and subsequently analyzed for a suite of 13 metals using a PerkinElmer DRC II ICP-MS. The analytical results were compared using either a paired t-test or a sign test depending on data normality.

RESULTS

Concentrations of metals (aluminum (Al), arsenic (As), barium (Ba), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), gadolinium (Gd), mercury (Hg), manganese (Mn), lead (Pb), strontium (Sr), and zinc (Zn)) measured in both types of tissue preparations (frozen and FFPE) displayed a consistent range with other studies and did not display significantly different values from each of the paired specimens for any of the 13 specific metals analyzed.

DISCUSSION

Within placentae, metals concentrations of measured trace, toxic and diagnostic elements (Al, As, Ba, Cd, Cr, Cu, Fe, Gd, Hg, Mn, Pb, Sr, and Zn) are consistent between FFPE and fresh placental villus tissue, without indications of systematic element loss or bias. FFPE from archived pathology specimens may offer an important and convenient alternative for measuring trace metals in human frozen placental tissues.

Current advancement in the development of manganese complexes as magnetic resonance imaging probes

Emerging non-invasive molecular imaging modalities can detect a pathophysiological state at the molecular level before any anatomic changes are observed. Magnetic resonance imaging (MRI) is preferred over other nuclear imaging techniques owing to its radiation-free approach. Conventionally, most MRI contrast agents employed predominantly involve lanthanide metal: Gadolinium (Gd) until the discovery of associated severe nephrogenic toxicity issues. This limitation led a way to the development of manganese-based contrast agents which offer similar positive contrast enhancement capability. A vast quantity of experimental data has been accumulated over the last decade to define the physicochemical characteristics of manganese chelates with various ligand scaffolds. One can now observe how the ligand configurations, rigidity, and donor-acceptor characteristics impact the stability of the complex. This review covers the current trends in the development of manganese-based MRI contrast agents, the mechanisms they are based on and design considerations for newer manganese-based contrast agents with higher diagnostic strength along with better safety profiles.

Different Impact of Gadopentetate and Gadobutrol on Inflammation-Promoted Retention and Toxicity of Gadolinium Within the Mouse Brain

OBJECTIVES

Using a murine model of multiple sclerosis, we previously showed that repeated administration of gadopentetate dimeglumine led to retention of gadolinium (Gd) within cerebellar structures and that this process was enhanced with inflammation. This study aimed to compare the kinetics and retention profiles of Gd in inflamed and healthy brains after application of the macrocyclic Gd-based contrast agent (GBCA) gadobutrol or the linear GBCA gadopentetate. Moreover, potential Gd-induced neurotoxicity was investigated in living hippocampal slices ex vivo.

MATERIALS AND METHODS

Mice at peak of experimental autoimmune encephalomyelitis (EAE; n = 29) and healthy control mice (HC; n = 24) were exposed to a cumulative dose of 20 mmol/kg bodyweight of either gadopentetate dimeglumine or gadobutrol (8 injections of 2.5 mmol/kg over 10 days). Magnetic resonance imaging (7 T) was performed at baseline as well as at day 1, 10, and 40 post final injection (pfi) of GBCAs. Mice were sacrificed after magnetic resonance imaging and brain and blood Gd content was assessed by laser ablation-inductively coupled plasma (ICP)-mass spectrometry (MS) and ICP-MS, respectively. In addition, using chronic organotypic hippocampal slice cultures, Gd-induced neurotoxicity was addressed in living brain tissue ex vivo, both under control or inflammatory (tumor necrosis factor α [TNF-α] at 50 ng/μL) conditions.

RESULTS

Neuroinflammation promoted a significant decrease in T1 relaxation times after multiple injections of both GBCAs as shown by quantitative T1 mapping of EAE brains compared with HC. This corresponded to higher Gd retention within the EAE brains at 1, 10, and 40 days pfi as determined by laser ablation-ICP-MS. In inflamed cerebellum, in particular in the deep cerebellar nuclei (CN), elevated Gd retention was observed until day 40 after last gadopentetate application (CN: EAE vs HC, 55.06 ± 0.16 μM vs 30.44 ± 4.43 μM). In contrast, gadobutrol application led to a rather diffuse Gd content in the inflamed brains, which strongly diminished until day 40 (CN: EAE vs HC, 0.38 ± 0.08 μM vs 0.17 ± 0.03 μM). The analysis of cytotoxic effects of both GBCAs using living brain tissue revealed an elevated cell death rate after incubation with gadopentetate but not gadobutrol at 50 mM. The cytotoxic effect due to gadopentetate increased in the presence of the inflammatory mediator TNF-α (with vs without TNF-α, 3.15% ± 1.18% vs 2.17% ± 1.14%; P = 0.0345).

CONCLUSIONS

In the EAE model, neuroinflammation promoted increased Gd retention in the brain for both GBCAs. Whereas in the inflamed brains, efficient clearance of macrocyclic gadobutrol during the investigated time period was observed, the Gd retention after application of linear gadopentetate persisted over the entire observational period. Gadopentetate but not gadubutrol appeared to be neurotoxic in an ex vivo paradigm of neuronal inflammation.

Use of Real-Life Safety Data From International Pharmacovigilance Databases to Assess the Importance of Symptoms Associated With Gadolinium Exposure

OBJECTIVE

Recent scientific publications have reported cases of patients who complained from a variety of symptoms after they received a gadolinium-based contrast agent (GBCA). The aim of this study was to appreciate the importance of these clinical manifestations in the overall population by assessing the weight of "symptoms associated with gadolinium exposure" (SAGE) among the bulk of safety experiences reported to major health authorities.

MATERIALS AND METHODS

Symptoms associated with gadolinium exposure were identified from a review of the scientific literature, and the corresponding preferred terms were searched in each system organ class (SOC) category recorded in the European and North American pharmacovigilance databases EudraVigilance (EV) and FDA Adverse Event Reporting System (FAERS), respectively. The numbers of SAGE per preferred term, and cumulatively per SOC, were recorded and their weights in the overall spectrum of adverse events (AEs) were determined for each GBCA.

RESULTS

The analysis of the selected AEs revealed a significantly higher SAGE weight for gadobenate dimeglumine (EV: 25.83%, FAERS: 32.24%) than for gadoteridol (EV: 15.51%; FAERS: 21.13%) and significantly lower SAGE weights for gadobutrol (EV: 7.75%; FAERS: 13.31%) and gadoterate meglumine (EV: 8.66%; FAERS: 12.99%). A similar ranking was found for most of the SOCs except for "nervous system disorders," probably owing to a limitation in the methods of data selection. Furthermore, this analysis showed a greater percentage of reports mentioning a decrease in the quality of life of the patients when they were exposed to gadobenate dimeglumine or gadoteridol than to gadobutrol or gadoterate meglumine.

CONCLUSION

This study showed that SAGE represent a significant percentage of the bulk of AEs reported to the health authorities for each GBCA. It provided real-life arguments suggesting that SAGE may be more prevalent with linear than macrocyclic GBCAs and that gadoteridol may present a higher SAGE risk than the other macrocyclic contrast agents.

Naturally grown duckweeds as quasi-hyperaccumulators of rare earth elements and yttrium in aquatic systems and the biounavailability of gadolinium-based MRI contrast agents

The use of rare earths and yttrium (REY) in high-technology products is accompanied by their increasing release into the environment. Concerns regarding the (eco-)toxicity and bioaccumulation of these emerging contaminants highlight the need for research on REY uptake by (aquatic) plants. Duckweeds are widespread macrophytes in lentic waters and receive increasing attention as a potential protein-rich food additive. We here provide a baseline dataset for the complete set of REY in naturally grown duckweed assemblages and ambient freshwater and coastal brackish seawater. Our results show that duckweeds strongly bioaccumulate REY and incorporate them at the μg/kg level (dry matter basis). Their shale-normalised (_SN) REY patterns are mildly fractionated relative to upper continental crust, regardless of sampling location and season. In contrast, the patterns of ambient waters increase from light to heavy REY (LREY and HREY, resp.) and may show prominent positive anthropogenic Gd_SN anomalies due to the presence of Gd-based contrast agents (Gd-CAs) applied for magnetic resonance imaging (MRI). The lack of Gd_SN anomalies in the duckweed assemblages reveals discrimination against the uptake of Gd-CAs by the macrophytes, providing further evidence for the conservative behaviour of these xenobiotics in the environment. High REY concentrations and apparent bulk distribution coefficients between duckweeds and ambient waters of up to 10⁵ show that duckweeds are quasi-hyperaccumulators of REY. Uptake of LREY is up to two orders of magnitude higher than of HREY, possibly due to stronger complexation of HREY with dissolved ligands. The REY closely correlate with Mn but not with Ca, suggesting that uptake of REY and Mn occurs via the same pathway and revealing the negligible role of calcium oxalates. Our study demonstrates that while duckweeds are quasi-hyperaccumulators of REY, there is currently no risk that anthropogenic Gd from MRI contrast agents may enter the food chain via consumption of duckweeds.

Safety considerations related to intravenous contrast agents in pediatric imaging

Intravenous contrast media are used in MRI, CT and US studies for anatomical evaluation and lesion characterization. Safety is always of paramount importance when administering any contrast media to children, and it is important for radiologists and ordering providers to be knowledgeable of the safety profiles and potential adverse events that can occur. This manuscript reviews the frequency and types of adverse events associated with intravenous contrast agents reported in the pediatric literature. Overall, intravenous contrast agents are very safe to use in children. However, familiarity with how to treat and prevent these uncommon events is crucial in preventing poor outcomes. In addition, an understanding of gadolinium deposition in tissues can help facilitate conversations with concerned physicians and parents. This review provides a concise yet comprehensive reference for radiologists and ordering providers on intravenous contrast safety considerations in the pediatric patient.

Polysaccharide-Based Theranostic Systems for Combined Imaging and Cancer Therapy: Recent Advances and Challenges

Designing novel systems for efficient cancer treatment and improving the quality of life for patients is a prime requirement in the healthcare sector. In this regard, theranostics have recently emerged as a unique platform, which combines the benefits of both diagnosis and therapeutics delivery. Theranostics have the desired contrast agent and the drugs combined in a single carrier, thus providing the opportunity for real-time imaging to monitor the therapy results. This helps in reducing the hazards related to treatment overdose or underdose and gives the possibility of personalized therapy. Polysaccharides, as natural biomolecules, have been widely explored to develop theranostics, as they act as a matrix for simultaneously loading both contrast agents and drugs for their utility in drug delivery and imaging. Additionally, their remarkable physicochemical attributes (biodegradability, satisfactory safety profile, abundance, and diversity in functionality and charge) can be tuned via postmodification, which offers numerous possibilities to develop theranostics with desired characteristics. Hence, we provide an overview of recent advances in polysaccharide matrix-based theranostics for drug delivery combined with magnetic resonance imaging, computed tomography, positron emission tomography, single photon emission computed tomography, and ultrasound imaging. Herein, we also summarize the toxicity assessment of polysaccharides, associated contrast agents, and nanotoxicity along with the challenges and future research directions.

The Abundance of Trace Elements in Human Bone Relative to Bone Type and Bone Pathology

As the global population ages and the proportion of individuals afflicted with musculoskeletal disease spirals upward, there is an increasing interest in understanding and preventing bone-related diseases. Bone diseases, such as osteoporosis and osteoarthritis, are known to be influenced by a variety of factors including age, gender, nutrition, and genetics, but are also inherently linked to the human body's ability to produce biominerals of suitable quality. Because the crystal lattice structure and mineralogy of bone hydroxyapatite is surprisingly analogous to geological hydroxyapatite, trace element levels and exposure have long been proposed to influence the structure of biominerals as they do geological minerals (e.g., strontium substitution changes the crystal lattice of bone minerals, while toxic lead disrupt bone cellular processes leading to bone disease). Here, we explore the distribution of trace elements in human bones to evaluate the distribution of these elements with respect to bone type (cortical vs. trabecular) and bone disease (osteoarthritis vs. osteoporosis). We find higher concentrations of many metabolically active transition metals, as well as lead, in cortical bone compared to trabecular bone. When compared to patients who have osteoarthritis, and thus presumably normal bone minerals, osteoporosis patients have higher concentrations of scandium and chromium (Cr) in trabecular bone, and Cr and lead in cortical bone. Lower concentrations of barium and titanium are associated with osteoporotic trabecular bone. This survey is an exploratory cross-sectional geochemical examination of several trace element concentrations previously understudied in human bone minerals.

Effect of formalin fixation on measured concentrations of deposited gadolinium in human tissue: an autopsy study

BACKGROUND

Generally, studies of gadolinium (Gd) deposition in humans measure concentration by analyzing formalin fixed postmortem tissue. However, the effect of formalin fixation on measured Gd concentration has not been well investigated.

PURPOSE

To evaluate the effect of fixation by comparing Gd concentration in fresh versus formalin-fixed postmortem human tissues.

MATERIAL AND METHODS

Fresh samples of bone and skin were collected from autopsy cases with previous exposure to Gd-based contrast agents (GBCAs). The type of GBCA administered, dose, and estimated glomerular filtration rate were recorded. Each tissue sample was cut into three aliquots. Paired samples were stored fresh frozen while the remaining two were stored in 10% neutral buffered formalin for one and three months, respectively. Gd concentration was measured using ICP-MS.

RESULTS

Of 18 autopsy cases studied, 12 were exposed to only macrocyclic GBCA, one to only linear agents, and five received both macrocyclic and linear agents. On average, Gd concentration for bone decreased 30.7% after one month of fixation (P = 0.043) compared to non-fixed values. There was minimal, if any, change in concentration between one and three months (average decrease 1.5%; P = 0.89). The findings were numerically similar for skin tissue with an average decrease of 36.9% after one month (P = 0.11) and 6.0% (P = 0.73) between one and three months.

CONCLUSION

Formalin fixation appears to decrease Gd concentration in bone and skin by approximately 30%-40% on average. The largest decrease occurs within the first 30 days of fixation followed by a considerably smaller decrease at 60 days.

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.

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.

Altered Plasma Mitochondrial Metabolites in Persistently Symptomatic Individuals after a GBCA-Assisted MRI

Despite the impressive safety of gadolinium (Gd)-based contrast agents (GBCAs), a small number of patients report the onset of new, severe, ongoing symptoms after even a single exposure—a syndrome termed Gadolinium Deposition Disease (GDD). Mitochondrial dysfunction and oxidative stress have been repeatedly implicated by animal and in vitro studies as mechanisms of Gd/GBCA-related toxicity, and as pathogenic in other diseases with similarities in presentation. Here, we aimed to molecularly characterize and explore potential metabolic associations with GDD symptoms. Detailed clinical phenotypes were systematically obtained for a small cohort of individuals (n = 15) with persistent symptoms attributed to a GBCA-enhanced MRI and consistent with provisional diagnostic criteria for GDD. Global untargeted mass spectroscopy-based metabolomics analyses were performed on plasma samples and examined for relevance with both single marker and pathways approaches. In addition to GDD criteria, frequently reported symptoms resembled those of patients with known mitochondrial-related diseases. Plasma differences compared to a healthy, asymptomatic reference cohort were suggested for 45 of 813 biochemicals. A notable proportion of these are associated with mitochondrial function and related disorders, including nucleotide and energy superpathways, which were over-represented. Although early evidence, coincident clinical and biochemical indications of potential mitochondrial involvement in GDD are remarkable in light of preclinical models showing adverse Gd/GBCA effects on multiple aspects of mitochondrial function. Further research on the potential contributory role of these markers and pathways in persistent symptoms attributed to GBCA exposure is recommended.

Tannin-Mn coordination polymer coated carbon quantum dots nanocomposite for fluorescence and magnetic resonance bimodal imaging

The MR/FI bimodal imaging has attracted widely studied due to combining the advantages of MRI and FI can bridge gaps in sensitivity and depth between these two modalities. Herein, a novel MR/FI bimodal imaging probe is facile fabricated by coating the Mn-phenolic coordination polymer on the surface of the carbon quantum dots. The structure of the as-prepared nanocomposite probe is carefully validated via SEM, TEM, and XPS. The content of Mn²⁺ is calculated through the EDS and TGA. The quantum yield (QY) and emission wavelength of the probe are about 7.24% and 490 nm, respectively. The longitudinal r1 value (2.43 mM^-1 s^-1) with low r2/r1 (4.45) of the probe is obtained. Subsequently, fluorescence and MR imaging are performed. The metabolic pathways in vivo are inferred by studying the bio-distribution of the probe in major organs. Thus, these results indicate that probe would be an excellent dual-modal imaging probe for enhanced MR imaging and fluorescence imaging. MR/FI bimodal imaging probe is built via in-situ coated Mn-phenolic coordination polymer on the surface of the carbon quantum dots. The in vitro and vivo image property of the probe is evaluated.

Dynamic Serial Cytokine Measurements During Intravenous Ca-DTPA Chelation in Gadolinium Deposition Disease and Gadolinium Storage Condition: A Pilot Study

PURPOSE

The aim of this study was to investigate the feasibility of measuring early changes in serum cytokine levels after intravenous diethylenetriaminepentaacetic acid (Ca-DTPA) chelation in patients manifesting either gadolinium deposition disease (GDD) or gadolinium storage condition (GSC) and the possible usefulness of this method in further research.

METHODS

Four patients with recent-onset GDD (≤1 year) and 2 patients with long-standing GSC (4 and 9 years) underwent chelation with intravenous bolus administration of Ca-DTPA. Multiple blood draws were performed to measure serum cytokines: at T = 0 (before Ca-DTPA injection) and 1, 5, 10, 30, 60 minutes, and 24 hours after Ca-DTPA injection. Patients rated the severity of GDD symptom flare at 24 hours. The 24-hour urine Gd amounts were measured prechelation and for the 24 hours after chelation. Serum samples were analyzed blind to whether patients had GDD or GSC but with knowledge of the time points characterizing each sample.

RESULTS

Urine samples for both GDD and GSC patients showed increases in Gd postchelation. All GDD patients experienced flare reactions postchelation; the 2 GSC patients did not. Two cytokines, EGF and sCD40L, peaked at 30 minutes postchelation in at least 4 of the 6 participants. Three cytokines, ENA78/CXCL5, EOTAXIN/CCL11, and LEPTIN, peaked at 24 hours in at least 4 of the 6 participants. Two participants were high outliers for a large number of cytokines across time points. No clear distinction between GDD and GSC was apparent from the cytokine patterns, although differences were present.

CONCLUSIONS

This pilot study describes precise temporal resolution (in the range of minutes) after a cytokine-inciting event. Select cytokines exhibited peak values at different time points. At this preliminary stage of investigation, peak cytokine release seems to reflect the amount of Gd mobilized rather than the severity of the patient symptomatic reaction. Too few subjects were studied to support statistical analysis between GDD and GSC groups, although differences were observed through visual data analysis.

Rational fabrication of a new ionic imprinted carboxymethyl chitosan-based sponge for efficient selective adsorption of Gd(iii)

In this work, a new PEI-CMC-IIS adsorbent with 3D network structure was fabricated for the selective adsorption of Gd(iii).

Gadolinium retention after contrast-enhanced magnetic resonance imaging: A narratative review

Over the past five years, several studies have reported deposition and retention of gadolinium in the brain after administration of gadolinium-based contrast agents (GBCAs) during radiological procedures. Patients with renal insufficiency cannot filter gadolinium efficiently; however, gadolinium is also retained in the brain of some adults and pediatrics with no renal impairment. In the literature, data is mostly available from retrospective magnetic resonance imaging (MRI) studies, where gadolinium deposition may be indirectly measured by evaluating changes in T1 signal intensity in the brain tissues, particularly in the deep gray matter such as the dentate nucleus and/or globus pallidus. Many pathological studies have reported a direct correlation between T1 signal changes and gadolinium deposition in human and animal autopsy specimens, which raised concerns on the use of GBCAs, particularly with linear chelators. The association between gadolinium accumulation and occurrence of physical and neurological side effects or neurotoxic damage has not yet been conclusively demonstrated. Studies have also observed that gadolinium is deposited in the extracranial tissues, such as the liver, skin, and bone, of patients with normal kidney function. This narrative review describes the effects of different types of GBCAs in relation to gadolinium deposition, evaluates current evidence on gadolinium deposition in various tissues of the human body, and summarizes the current recommendations regarding the use of GBCAs.

How the Chemical Properties of GBCAs Influence Their Safety Profiles In Vivo

The extracellular class of gadolinium-based contrast agents (GBCAs) is an essential tool for clinical diagnosis and disease management. In order to better understand the issues associated with GBCA administration and gadolinium retention and deposition in the human brain, the chemical properties of GBCAs such as relative thermodynamic and kinetic stabilities and their likelihood of forming gadolinium deposits in vivo will be reviewed. The chemical form of gadolinium causing the hyperintensity is an open question. On the basis of estimates of total gadolinium concentration present, it is highly unlikely that the intact chelate is causing the T1 hyperintensities observed in the human brain. Although it is possible that there is a water-soluble form of gadolinium that has high relaxitvity present, our experience indicates that the insoluble gadolinium-based agents/salts could have high relaxivities on the surface of the solid due to higher water access. This review assesses the safety of GBCAs from a chemical point of view based on their thermodynamic and kinetic properties, discusses how these properties influence in vivo behavior, and highlights some clinical implications regarding the development of future imaging agents.

Multimodal ex vivo methods reveal that Gd-rich corrosion byproducts remain at the implant site of biodegradable Mg-Gd screws

Extensive research is being conducted on magnesium (Mg) alloys for bone implant manufacturing, due to their biocompatibility, biodegradability and mechanical properties. Gadolinium (Gd) is among the most promising alloying elements for property control in Mg alloy implants; however, its toxicity is controversial. Investigating Gd behavior during implant corrosion is thus of utmost importance. In this study, we analyzed the degradation byproducts at the implant site of biodegradable Mg-5Gd and Mg-10Gd implants after 12 weeks healing time, using a combination of different imaging techniques: histology, energy-dispersive x-ray spectroscopy (EDX), x-ray microcomputed tomography (µCT) and neutron µCT. The main finding has been that, at the healing time in exam, the corrosion appears to have involved only the Mg component, which has been substituted by calcium and phosphorus, while the Gd remains localized at the implant site. This was observed in 2D by means of EDX maps and extended to 3D with a novel application of neutron tomography. X-ray fluorescence analysis of the main excretory organs also did not reveal any measurable accumulation of Gd, further reinforcing the conclusion that very limited or no removal at all of Gd-alloy happened during degradation. STATEMENT OF SIGNIFICANCE: Gadolinium is among the most promising alloying elements for property control in biodegradable magnesium alloy implants, but its toxicity is controversial and its behavior during corrosion needs to be investigated. We combine 2D energy dispersive x-ray spectroscopy and 3D neutron and x-ray tomography to image the degradation of magnesium-gadolinium implants after 12 weeks of healing time. We find that, at the time in exam, the corrosion has involved only the magnesium component, while the gadolinium remains localized at the implant site. X-ray fluorescence analysis of the main excretory organs also does not reveal any measurable accumulation of Gd, further reinforcing the conclusion that very limited or no removal at all of Gd-alloy has happened during degradation.

Mild Dissolution/Recomplexation Strategy for Speciation Analysis of Gadolinium from MR Contrast Agents in Bone Tissues by Means of HPLC-ICP-MS

A species-dependent and total gadolinium quantification strategy for the analysis of bone and bone marrow samples was developed and applied to femurs of rats previously treated with different gadolinium-based contrast agents (GBCAs). A combined mild dissolution/recomplexation strategy allows the quantification of total Gd as well as the quantification of intact GBCA in bones within one analysis for the first time. Samples of rat bones and bone marrow were dissolved in low concentrations of hydrochloric acid and diethylenetriamine pentaacetate (DTPA). This is followed by the addition of excess In(III) to recomplex all free ligands, previously added DTPA as well as the ligands of GBCAs that were not stable during the dissolution step. Separation and quantification were carried out by means of high-performance liquid chromatography (HPLC) on a hydrophilic interaction liquid chromatography (HILIC) column with subsequent inductively coupled plasma-mass spectrometry (ICP-MS). The results show that the investigated GBCA with a macrocyclic ligand shows a higher tendency to stay intact in the bone tissues over time, while a GBCA with a linear ligand is decomplexed more rapidly four weeks after GBCA administration. Additionally, for all macrocyclic GBCAs, a similar limited gadolinium accumulation was observed in the bone and bone marrow. Whereas linear GBCAs showed a higher gadolinium accumulation, a difference was observed between bone and bone marrow, indicating a different biodistribution behavior.

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.

Physicians with self-diagnosed gadolinium deposition disease: a case series

Objective

The objective of this study was to allow physicians with self-diagnosed gadolinium deposition disease symptoms to report their own experience.

Materials and Methods

Nine physicians (seven females), with a mean age of 50.5 ± 8.3 years, participated in this case series. Nationalities were American (n = 6), British, Portuguese, and Romanian. Medical practices included internal medicine (n = 2), trauma surgery, ophthalmology, gastroenterology, psychiatry, family medicine, obstetrics/gynecology, and general practice.

Results

Genetically, eight of the physicians were of central European origin. Underlying autoimmune conditions were present in four. Symptoms developed after a single injection in one physician and after multiple injections in eight. The precipitating agent was gadobenate dimeglumine in four physicians, gadobutrol in three, gadoterate meglumine in one, and gadopentetate dimeglumine in one. The most consistent symptoms were a burning sensation, brain fog, fatigue, distal paresthesia, fasciculations, headache, and insomnia. Eight of the physicians were compelled to change their practice of medicine.

Conclusion

In the various physicians, gadolinium deposition disease showed common features and had a substantial impact on daily activity. Physicians are educated reporters on disease, so their personal descriptions should spark interest in further research.

Pharmacokinetics, Dialysability, and Safety of Gadopiclenol, a New Gadolinium-Based Contrast Agent, in Patients With Impaired Renal Function

OBJECTIVES

The aims of this study were to evaluate the pharmacokinetics (PK) of gadopiclenol, a new macrocyclic gadolinium based-contrast agent, in subjects with impaired renal function, and to assess its dialysability in subjects with end-stage renal disease (ESRD).

METHODS AND MATERIALS

This 2-center, open-label, phase 1 study included 5 successive cohorts of 8 adult subjects: healthy subjects (cohort 1), subjects with mild (cohort 2), moderate (cohort 3), severe (cohort 4) renal impairment, or ESRD (cohort 5), who received a single intravenous injection of gadopiclenol (0.1 mmol/kg). Blood and urine samples were collected at different time points in cohorts 1 to 4, and blood and dialysate samples were collected at each hemodialysis session (4-hour session on day 1, day 3, and day 5) in cohort 5. Gadopiclenol elimination and safety were assessed for up to 6 months. Pharmacokinetics parameters were calculated using noncompartmental analysis.

RESULTS

A total of 40 subjects were included, with a mean age of 51.5 years (range, 18-71 years). No significant difference in the mean maximum concentration values and the distribution volume was observed among cohorts 1 to 4. Urinary excretion of unchanged gadopiclenol was delayed with the degree of renal impairment and ranged between 96% and 84% in subjects with mild to severe renal impairment. Compared with that of healthy subjects, the mean area under the plasma concentration curve was 54%, 148%, and 769% higher in subjects with mild, moderate, or severe renal impairment, respectively. The mean terminal half-life was prolonged with the degree of renal impairment (1.9, 3.3, 3.8, and 11.7 hours for cohorts 1-4). In ESRD subjects, gadopiclenol was effectively removed from the plasma (95% to 98%) after the first hemodialysis session. Gadopiclenol concentration in plasma was below the limit of quantification for all subjects after the second hemodialysis session. Gadopiclenol concentration was below limit of quantification in all plasma and urine samples collected at 1, 3, and 6 months. Five subjects (12.5%) experienced adverse events related to gadopiclenol, none serious and all resolved. Laboratory measurements, vital signs, and electrocardiography did not raise any safety concern.

CONCLUSIONS

Gadopiclenol elimination half-life was prolonged in subjects with mild to severe renal impairment, yet its renal clearance remains complete or nearly complete. In ESRD subjects, gadopiclenol was effectively removed from the plasma after 1 hemodialysis session, and up to 3 hemodialysis sessions were sufficient to completely clear it. No safety concern was raised. Therefore, no dose adjustment seems necessary in this patient population.

Gadolinium based contrast agents in current practice: Risks of accumulation and toxicity in patients with normal renal function

Despite being decked as the most prized compounds in the nugget box of contrast agents for clinical radiologists, and carrying an indisputable tag of safety of the US Food and Drug Administration for close to three decades, all may not be seemingly well with the family of gadolinium compounds. If the first signs of violations of primum non nocere in relation to gadolinium-based contrast agents (GBCAs) appeared in the millennium year with the first published report of skin fibrosis in patients with compromised renal function, the causal relationship between the development of nephrogenic systemic fibrosis (NSF) and GBCAs, first proposed by two European groups in 2006, further precluded their use in renocompromised patients. The toxicity, pharmacokinetics, and pharmacodynamics of GBCAs, however, has come under hawk-eyed scrutiny with recent reports that gadolinium tends to deposit cumulatively in the brain of patients with normal hepatobiliary function and intact blood–brain barrier. While the jury on the long-term hazard significance of this critical scientific finding is still out, the use of GBCAs must be guided by due clinical diligence, avoidance of repeated doses, and preferring GBCAs with the best safety profiles.