Gadolinium Deposition Disease: Current State of Knowledge and Expert Opinion

Clinical Safety of Gadobutrol: Review of Over 25 Years of Use Exceeding 100 Million Administrations

BACKGROUND

The macrocyclic gadolinium-based contrast agent gadobutrol was introduced to the market in February 1998. Over the last 25 years, gadobutrol has been administered more than 100 million times worldwide providing a wealth of data related to safety.

OBJECTIVE

The aim of this study was to perform a thorough review and status update on gadobutrol's safety.

MATERIALS AND METHODS

Safety data from the clinical phase II-IV program and postmarketing surveillance were descriptively analyzed from February 1998 until December 31, 2022. Literature on special at-risk populations and specific safety aspects was critically summarized.

RESULTS

Forty-five clinical phase II-IV studies recruited 7856 patients receiving gadobutrol. Drug-related adverse events (AEs) were reported in 3.4% and serious AEs in <0.1% of patients. Nausea (0.7%) and dysgeusia (0.4%) were the most reported AEs. All other drug-related AEs occurred ≤0.3%. After more than 100 million gadobutrol administrations, overall adverse drug reactions (ADRs) from postmarketing surveillance (including clinical trials) were rare with an overall reporting rate of 0.0356%, hypersensitivity reactions (0.0147%), nausea (0.0032%), vomiting (0.0025%), and dyspnea (0.0010%). All other ADRs were <0.001%. No trend for higher rates of AEs was found in patients with reduced renal or liver function. Seven clinical studies reported safety findings in 7292 children ≤18 years, thereof 112 newborns/toddlers younger than 2 years. Overall, 61 ADRs (0.84%) were reported, including 3 serious ones. Adverse events in patients ≥65 years of age ("elderly") were significantly less frequent than in younger patients. A total of 4 reports diagnostic of or consistent with nephrogenic systemic fibrosis have been received. No causal relationship has been established between clinical signs and symptoms and the presence of small amounts of gadolinium in the body in patients with normal renal function after use of gadobutrol.

CONCLUSIONS

More than 100 million administrations worldwide have shown gadobutrol's well-established benefit-risk profile in any approved indication and populations.

Differences in hypersensitivity reactions and gadolinium deposition disease/symptoms associated with gadolinium exposure to gadolinium-based contrast agents: new insights based on global databases VigiBase, FAERS, and IQVIA-MIDAS

BACKGROUND

Hypersensitivity reactions (HSRs) can occur unexpectedly and be life-threatening when gadolinium-based contrast agents (GBCAs) are used. Gadolinium deposition disease (GDD) and symptoms associated with gadolinium exposure (SAGE) have been controversial for a long time. However, similar studies are currently incomplete or outdated. Therefore, comparing the safety of different GBCAs in terms of HSRs and GDD/SAGE using the latest post-marketing safety data should yield further insights into safely using GBCAs.

METHODS

The safety differences between all GBCAs to GDD and the spectrum of GBCA-related HSRs were all compared and analyzed by using the World Health Organization database VigiBase and the FDA Adverse Event Reporting System (FAERS) database in this study. A further analysis of SAGE was also conducted using FAERS data. The lower limit of the reporting odds ratio (ROR) 95% confidence interval was used for signal detection. Moreover, the frequency of HSRs was calculated by dividing the number of reports in VigiBase by the total sales volume (measured in millions) from 2008 to 2022 in the IQVIA Multinational Integrated Data Analysis System. All adverse events were standardized using the Medical Dictionary for Drug Regulatory Activities (MedDRA) 26.0.

RESULTS

This study shows that all GBCAs have the potential to induce HSRs, with nonionic linear GBCAs exhibiting a comparatively lower signal. According to standardized MedDRA query stratification analysis, gadobutrol had a greater ROR025 for angioedema. The ROR025 of gadobenate dimeglumine and gadoteridol is larger for anaphylactic/anaphylactoid shock conditions. Regarding severe cutaneous adverse reactions, only gadoversetamide and gadodiamide showed signals in FAERS and VigiBase. There were also differences in the frequency of HSRs between regions. Regarding GDD, gadoterate meglumine, and gadoteridol had a lower ROR025. An analysis of the 29 preferred terms linked to SAGE indicated that special consideration should be given to the risk of skin induration associated with gadoversetamide, gadopentetate dimeglumine, gadobenate dimeglumine, gadodiamide, and gadoteridol. Additionally, gadodiamide and gadoteridol pose a greater risk of skin tightness compared to other GBCAs.

CONCLUSIONS

The risk differences among GBCAs using data from several sources were compared in this study. However, as a hypothesis-generating method, a clear causal relationship would require further research and validation.

The safety of magnetic resonance imaging contrast agents

Gadolinium-based contrast agents are increasingly used in clinical practice. While these pharmaceuticals are verified causal agents in nephrogenic systemic fibrosis, there is a growing body of literature supporting their role as causal agents in symptoms associated with gadolinium exposure after intravenous use and encephalopathy following intrathecal administration. Gadolinium-based contrast agents are multidentate organic ligands that strongly bind the metal ion to reduce the toxicity of the metal. The notion that cationic gadolinium dissociates from these chelates and causes the disease is prevalent among patients and providers. We hypothesize that non-ligand-bound (soluble) gadolinium will be exceedingly low in patients. Soluble, ionic gadolinium is not likely to be the initial step in mediating any disease. The Kidney Institute of New Mexico was the first to identify gadolinium-rich nanoparticles in skin and kidney tissues from magnetic resonance imaging contrast agents in rodents. In 2023, they found similar nanoparticles in the kidney cells of humans with normal renal function, likely from contrast agents. We suspect these nanoparticles are the mediators of chronic toxicity from magnetic resonance imaging contrast agents. This article explores associations between gadolinium contrast and adverse health outcomes supported by clinical reports and rodent models.

Deposition of Gadolinium in the Central and Peripheral Nervous Systems and Its Effects on Sensory, Cognitive, and Athletic Implications after Multiple Injections of Gadolinium-Based Contrast Agents in Rats

BACKGROUND AND PURPOSE

After repeat administration of gadolinium-based contrast agents (GBCAs), the association between gadolinium retention in the central and peripheral nervous systems and the main manifestations of myelopathy and progressive neurologic symptoms remains unclear. We investigated the effects of the repeat administration of GBCAs on gadolinium retention in the central and peripheral nervous systems and the sensory, cognitive, and athletic implications.

MATERIALS AND METHODS

Forty-eight male Wistar rats (6 weeks of age) were randomly divided into 4 experimental groups (12 rats in each group): the gadodiamide group (linear and nonionic GBCAs), the gadopentetate dimeglumine group (linear and ionic GBCAs), the gadoterate meglumine group (macrocyclic and ionic GBCAs), and the control group (0.9% saline solution). The brains of the rats were scanned using 9.4T MRI. Sensory behavioral tests were performed to assess the effect of GBCAs on pain sensitivity function. Gadolinium deposition in the brain, spinal cord, and peripheral nerves was determined by inductively coupled plasma mass-spectrometry. Transmission electron microscopy was used to observe the microscopic distribution of gadolinium after deposition in the spinal cord. The histopathologic features in the spinal cord were analyzed by H&E staining, Nissl staining, glial fibrillary acidic protein staining, and neuron-specific enolase staining after administration of GBCAs.

RESULTS

All GBCAs resulted in gadolinium deposition in the central and peripheral nerve tissues, with the highest deposition in the sciatic nerve tissue (mean, 62.86 [SD, 12.56] nmol/g). Decreased muscle power, impairment of spatial cognitive function power, and pain hypersensitivity to thermal and mechanical stimuli were observed after exposure to gadodiamide. At the spinal cord, transmission electron microscopy found that the region of gadolinium depositions had a spheric structure similar to "sea urchins" and was mainly located near the vascular basement membrane.

CONCLUSIONS

Multiple injections of GBCAs caused gadolinium deposition in the brain, spinal cord, and peripheral nerves, especially in the spinal cords of the gadodiamide group. Gadodiamide led to pain hypersensitivity and decreased muscle power and cognitive ability. For the patients who are hypersensitive to pain and need multiple MRI examinations, we recommend using macrocyclic GBCAs and the lowest dose possible.

Artificial T1-Weighted Postcontrast Brain MRI: A Deep Learning Method for Contrast Signal Extraction

OBJECTIVES

Reducing gadolinium-based contrast agents to lower costs, the environmental impact of gadolinium-containing wastewater, and patient exposure is still an unresolved issue. Published methods have never been compared. The purpose of this study was to compare the performance of 2 reimplemented state-of-the-art deep learning methods (settings A and B) and a proposed method for contrast signal extraction (setting C) to synthesize artificial T1-weighted full-dose images from corresponding noncontrast and low-dose images.

MATERIALS AND METHODS

In this prospective study, 213 participants received magnetic resonance imaging of the brain between August and October 2021 including low-dose (0.02 mmol/kg) and full-dose images (0.1 mmol/kg). Fifty participants were randomly set aside as test set before training (mean age ± SD, 52.6 ± 15.3 years; 30 men). Artificial and true full-dose images were compared using a reader-based study. Two readers noted all false-positive lesions and scored the overall interchangeability in regard to the clinical conclusion. Using a 5-point Likert scale (0 being the worst), they scored the contrast enhancement of each lesion and its conformity to the respective reference in the true image.

RESULTS

The average counts of false-positives per participant were 0.33 ± 0.93, 0.07 ± 0.33, and 0.05 ± 0.22 for settings A-C, respectively. Setting C showed a significantly higher proportion of scans scored as fully or mostly interchangeable (70/100) than settings A (40/100, P < 0.001) and B (57/100, P < 0.001), and generated the smallest mean enhancement reduction of scored lesions (-0.50 ± 0.55) compared with the true images (setting A: -1.10 ± 0.98; setting B: -0.91 ± 0.67, both P < 0.001). The average scores of conformity of the lesion were 1.75 ± 1.07, 2.19 ± 1.04, and 2.48 ± 0.91 for settings A-C, respectively, with significant differences among all settings (all P < 0.001).

CONCLUSIONS

The proposed method for contrast signal extraction showed significant improvements in synthesizing postcontrast images. A relevant proportion of images showing inadequate interchangeability with the reference remains at this dosage.

Near-cure in patients with Gadolinium deposition disease undergoing intravenous DTPA chelation

Purpose

To demonstrate and evaluate factors contributing to near-cures in patients with Gadolinium Deposition Disease (GDD) undergoing intravenous (IV) DTPA chelation.

Methods

Patients who had undergone or are currently undergoing DTPA chelation for GDD were included in this report based on their medical records that showed their perceived improvement was at least 80% back to normal. A survey was developed that included factors commonly reported by patients treated in one clinic to determine if these 'near-cured' (pre-MRI baseline health) individuals possessed certain factors and lacked others. The anonymized survey was emailed to these individuals by the principal treating physician, the only investigator not blinded to the subjects. This report describes clinical documentation of patient status and their underlying factors in individuals treated by the primary author, and no research was performed. The survey was sent to sixteen individuals; Fourteen patients completed it (10 females; 41.1 ± 11.2 y/o).

Results

The most common factor was the administration of ≤5 lifetime doses of a Gadolinium-Based Contrast Agents (GBCA) (12/14). Unconfounded agents triggering GDD were seen in nine subjects. Most subjects (12/14) initiated chelation in the first year after the causative GBCA, and most (11/14) underwent ≤10 chelations with DTPA. Good healthcare status prior to MRI was observed in 5 subjects. The majority (11/14) described their immune status as strong. Severe physical disability prior to chelation was seen in 1.

Conclusion

Subjects with GDD can experience near-cure with IV DTPA chelation. Factors surveyed that predict near-cure include the start of chelation in the first year, few GBCA administrations, and good health status before MRI with GBCA injection. Nonetheless, a few patients with predictors of less successful outcomes still experienced near-cure.

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.

Gadolinium retention effect on macrophages - a potential cause of MRI contrast agent Dotarem toxicity

Gadolinium is a component of the MRI contrast agent Dotarem. Although Dotarem is the least toxic among MRI contrasts used, gadolinium present in Dotarem accumulates for many years in various organs and tissues exerting toxic effects. We showed previously that gadolinium remains in macrophages for at least 7 days after exposure to Dotarem. However, very little is known about the effect of gadolinium retention on the immune cells such as macrophages. We studied the effect of 1-day and 7-day retention of gadolinium on various functions and molecular pathways of macrophages. Gadolinium retention for 7 days decreased macrophage adhesion and motility and dysregulated the expression of adhesion and fibrotic pathway-related proteins such as Notch1 and its ligand Jagged1, adhesion/migration-related proteins PAK1 and Shp1, immune response-related transcription factors Smad3 and TCF19, and chemokines CXCL10 and CXCL13, and dysregulated the mRNA expression of fibrosis-related genes involved in extracellular matrix (ECM) synthesis, such as Col6a1, Fibronectin, MMP9, and MMP12. It also completely (below a level of detection) shut down the transcription of anti-inflammatory M2 macrophage polarization marker the Arg-1. Such changes, if they occur in MRI patients, can be potentially detrimental to the patient's immune system and immune response-related processes.

Non-contrast preoperative MRI for determining renal perfusion and visualizing renal arteries in potential living kidney donors at 1.5 Tesla

Background

The aim of this work was to create and evaluate a preoperative non-contrast-enhanced (CE) magnetic resonance imaging (MRI)/angiography (MRA) protocol to assess renal function and visualize renal arteries and any abnormalities in potential living kidney donors.

Methods

In total, 28 subjects were examined using scintigraphy to determine renal function. In addition, 3D-pseudocontinuous arterial spin labeling (pCASL), a 2D-non-CE electrocardiogram-triggered radial quiescent interval slice-selective (QISS-MRA), and 4D-CE time-resolved angiography with interleaved stochastic trajectories (CE-MRA) were performed to assess renal perfusion, visualize renal arteries and detect any abnormalities. Two glomerular filtration rates [described by Gates (GFRG) and according to the Chronic Kidney Disease Epidemiology Collaboration formula (GFRCKD-EPI)]. The renal volumes were determined using both MRA techniques.

Results

The mean value of regional renal blood flow (rRBF) on the right side was significantly higher than that on the left. The agreements between QISS-MRA and CE-MRA concerning the assessment of absence or presence of an aberrant artery and renal arterial stenosis were perfect. The mean renal volumes measured in the right kidney with QISS-MRA were lower than the corresponding values of CE-MRA. In contrast, the mean renal volumes measured in the left kidney with both MRA techniques were similar. The correlation between the GFRG and rRBF was compared in the same manner as that between GFRCKD-EPI and rRBF.

Conclusion

The combination of pCASL and QISS-MRA constitute a reliable preoperative protocol with a total measurement time of <10 min without the potential side effects of gadolinium-based contrast agents or radiation exposure.

Uptake of Gadolinium-Based Contrast Agents by Blood Cells During Contrast-Enhanced MRI Examination

OBJECTIVES

Gadolinium-based contrast agents (GBCAs) are routinely used in magnetic resonance imaging (MRI) examinations. However, there is limited knowledge about the interaction with and distribution of the drug in human cells. This lack of knowledge is surprising, given that the first interaction of the drug occurs with blood cells. Moreover, recent studies reported gadolinium (Gd) deposition within organs, such as the brain. Hence, this study is aiming to determine the uptake of GBCA in blood cells of patients undergoing contrast-enhanced MRI (ce-MRI) examination.

MATERIALS AND METHODS

Human blood was exposed to either gadoterate meglumine (Gd-DOTA) or Eu-DOTA in vitro or was collected from patients undergoing ce-MRI with Gd-DOTA. Uptake of contrast agents (CAs) by blood cells was quantified by Gd measurements using single-cell inductively coupled plasma mass spectrometry (SC-ICP-MS) or, to confirm Gd-DOTA uptake, by a complementary method using Eu-DOTA by time-resolved fluorescence spectroscopy, respectively.

RESULTS

Uptake of Gd-DOTA or Eu-DOTA into white blood cells (WBCs) ex vivo was detectable by SC-ICP-MS and time-resolved fluorescence spectroscopy. The intracellular concentrations were estimated to be in the range of 1-3 μM. However, no CA uptake into erythrocytes was detected with either method. In total, 42 patients between 30 and 84 years old (24 men, 18 women) were enrolled. White blood cells' uptake of Gd was measured by SC-ICP-MS. Isolated WBCs from patients who underwent ce-MRI examination showed substantial Gd uptake; however, the studied patient group showed an inhomogeneous distribution of Gd uptake. Measurements immediately after MRI examination indicated 21-444 attogram/WBC, corresponding to an intracellular Gd concentration in the range from 0.2 to 5.5 μM.

CONCLUSIONS

This study confirms the ex vivo uptake of GBCA by WBCs and provides the first evidence that GBCA is indeed taken up by WBCs in vivo by patients undergoing ce-MRI examination. However, the observed Gd uptake in WBCs does not follow a log-normal distribution commonly observed in the fields of environmental studies, biology, and medicine. Whether cellular uptake of GBCA is linked to the observed deposition of Gd remains unclear. Therefore, studying the interaction between GBCA and human cells may clarify crucial questions about the effects of Gd on patients after MRI examinations.

Revolutionizing lymph node metastasis imaging: the role of drug delivery systems and future perspectives

The deployment of imaging examinations has evolved into a robust approach for the diagnosis of lymph node metastasis (LNM). The advancement of technology, coupled with the introduction of innovative imaging drugs, has led to the incorporation of an increasingly diverse array of imaging techniques into clinical practice. Nonetheless, conventional methods of administering imaging agents persist in presenting certain drawbacks and side effects. The employment of controlled drug delivery systems (DDSs) as a conduit for transporting imaging agents offers a promising solution to ameliorate these limitations intrinsic to metastatic lymph node (LN) imaging, thereby augmenting diagnostic precision. Within the scope of this review, we elucidate the historical context of LN imaging and encapsulate the frequently employed DDSs in conjunction with a variety of imaging techniques, specifically for metastatic LN imaging. Moreover, we engage in a discourse on the conceptualization and practical application of fusing diagnosis and treatment by employing DDSs. Finally, we venture into prospective applications of DDSs in the realm of LNM imaging and share our perspective on the potential trajectory of DDS development.

Comprehensive Analysis of the Spatial Distribution of Gadolinium, Iron, Manganese, and Phosphorus in the Brain of Healthy Rats After High-Dose Administrations of Gadodiamide and Gadobutrol

OBJECTIVES

After the administration of gadolinium-based contrast agents (GBCAs), residual gadolinium (Gd) has been detected in a few distinct morphological structures of the central nervous system (CNS). However, a systematic, comprehensive, and quantitative analysis of the spatial Gd distribution in the entire brain is not yet available. The first aim of this study is to provide this analysis in healthy rats after administration of high GBCA doses. The second aim is to assess the spatial distributions and possible Gd colocalizations of endogenous iron (Fe), manganese (Mn), and phosphorus (P). In addition, the presence of Gd in proximity to blood vessels was assessed by immunohistochemistry.

MATERIALS AND METHODS

Male rats were randomly assigned to 3 groups (n = 3/group): saline (control), gadodiamide (linear GBCA), and gadobutrol (macrocyclic GBCA) with cumulative Gd doses of 14.4 mmol/kg of body mass. Five weeks after the last administration, the brains were collected and cryosectioned. The spatial distributions of Gd, Fe, Mn, and P were analyzed in a total of 130 sections, each covering the brain in 1 of the 3 perpendicular anatomical orientations, using laser ablation coupled with inductively coupled plasma mass spectrometry. Quantitative spatial element maps were generated, and the concentrations of Gd, Fe, and Mn were measured in 31 regions of interest covering various distinct CNS structures. Correlation analyses were performed to test for possible colocalization of Gd, Fe, and Mn. The spatial proximity of Gd and blood vessels was studied using metal-tagged antibodies against von Willebrand factor with laser ablation coupled with inductively coupled plasma mass spectrometry.

RESULTS

After administration of linear gadodiamide, high Gd concentrations were measured in many distinct structures of the gray matter. This involved structures previously reported to retain Gd after linear GBCA, such as the deep cerebellar nuclei or the globus pallidus, but also structures that had not been reported so far including the dorsal subiculum, the retrosplenial cortex, the superior olivary complex, and the inferior colliculus. The analysis in all 3 orientations allowed the localization of Gd in specific subregions and layers of certain structures, such as the hippocampus and the primary somatosensory cortex. After macrocyclic gadobutrol, the Gd tissue concentration was significantly lower than after gadodiamide. Correlation analyses of region of interest concentrations of Gd, Fe, and Mn revealed no significant colocalization of Gd with endogenous Fe or Mn in rats exposed to either GBCA. Immunohistochemistry revealed a colocalization of Gd traces with vascular endothelium in the deep cerebellar nuclei after gadobutrol, whereas the majority of Gd was found outside the vasculature after gadodiamide.

CONCLUSIONS

In rats exposed to gadodiamide but not in rats exposed to gadobutrol, high Gd concentrations were measured in various distinct CNS structures, and structures not previously reported were identified to contain Gd, including specific subregions and layers with different cytoarchitecture and function. Knowledge of these distinct spatial patterns may pave the way for tailored functional neurological testing. Signs for the localization of the remaining Gd in the vascular endothelium were prominent for gadobutrol but not gadodiamide. The results also indicate that local transmetalation with endogenous Fe or Mn is unlikely to explain the spatial patterns of Gd deposition in the brain, which argues against a general role of these metals in local transmetalation and release of Gd ions in the CNS.

Oral Manganese Chloride Tetrahydrate: A Novel Magnetic Resonance Liver Imaging Agent for Patients With Renal Impairment: Efficacy, Safety, and Clinical Implication

ABSTRACT

Manganese-based contrast agents (MBCAs) show promise to complement gadolinium-based contrast agents (GBCAs) in magnetic resonance imaging (MRI) of the liver. Management of patients with focal liver lesions and severely impaired renal function uses unenhanced liver MRI or GBCA-enhanced MRI. However, unenhanced MRI risks reducing patient's survival.Gadolinium-based contrast agents, which help to detect and visualize liver lesions, are associated with increased risk of nephrogenic systemic fibrosis in renally impaired patients, a severe adverse event (AE) with potentially fatal outcome. Therefore, use of GBCA in patients with impaired renal function requires careful consideration. Other concerns are related to tissue deposition in the brain and other organs due to lack of gadolinium clearance, which could lead to concerns also for other patient populations, for example, those exposed to multiple procedures with GBCA. Of particular concern are the linear chelates that remain available for liver MRI, where there is no replacement technology. This has highlighted the urgency for safer alternatives.An alternative may be the drug candidate Ascelia-MBCA (ACE-MBCA, Orviglance), oral manganese chloride tetrahydrate. This candidate effectively visualizes and detects focal liver lesions, as demonstrated in 8 clinical studies on 201 adults (healthy or with known or suspected focal liver lesions). ACE-MBCA has a low and transient systemic exposure, which is likely the reason for its beneficial safety profile. The AEs were primarily mild and transient, and related to the gastrointestinal tract. This new, orally administered product may offer a simple imaging approach, allowing appropriate patient management in renally impaired patients when use of GBCA requires careful consideration.In this review, we highlight the clinical development of ACE-MBCA-a novel, liver-specific contrast agent. We begin with a brief overview of manganese properties, addressing the need for MBCAs and describing their optimal properties. We then review key findings on the novel agent and how this allows high-quality MRIs that are comparable to GBCA and superior to unenhanced MRI. Lastly, we provide our view of future perspectives that could advance the field of liver imaging, addressing the medical needs of patients with focal liver lesions and severe renal impairment.Our review suggests that ACE-MBCA is a promising, effective, and well-tolerated new tool in the radiologist's toolbox.

A New Era in Magnetic Resonance Contrast Media

ABSTRACT

Next-generation gadolinium-based contrast agents (GBCAs), including both high relaxivity agents and targeted agents, and manganese-based agents with a high probably of commercial success are discussed in some depth. It is highly likely that gadopiclenol and gadoquatrane, both next-generation high relaxivity gadolinium-based compounds, will come in time to replace the current macrocyclic gadolinium chelates, despite the wide acceptance, very high safety profile, and high stability of the latter group. Current research has also made possible the development of 2 new targeted gadolinium chelates, which look very promising, with the potential to improve cancer detection (for both MT218 and ProCA32.collagen) as well as diseases of collagen (for the latter agent). Further work with manganese-based compounds, a topic left fallow for more than 20 years, has also now produced 2 agents with high potential for clinical use, one (manganese chloride tetrahydrate, administered orally) developed primarily for imaging of the liver and the other (Mn-PyC3A, administered intravenously) as a gadolinium-free replacement for the GBCAs. New detail has recently emerged regarding specific circumscribed subregions of the brain with specialized cytoarchitecture and functions in which high gadolinium concentrations are seen following injection of the linear agent gadodiamide. These findings pave the way for tailored functional neurological testing, specifically in patients at potential risk due to the continued wide use in many countries across the world of the linear GBCAs. The impact of artificial intelligence is also critically discussed, with its most likely applications being dose reduction and new clinical indications.

Improving the Efficacy of Common Cancer Treatments via Targeted Therapeutics towards the Tumour and Its Microenvironment

Cancer is defined as the uncontrolled proliferation of heterogeneous cell cultures in the body that develop abnormalities and mutations, leading to their resistance to many forms of treatment. Left untreated, these abnormal cell growths can lead to detrimental and even fatal complications for patients. Radiation therapy is involved in around 50% of cancer treatment workflows; however, it presents significant recurrence rates and normal tissue toxicity, given the inevitable deposition of the dose to the surrounding healthy tissue. Chemotherapy is another treatment modality with excessive normal tissue toxicity that significantly affects patients' quality of life. To improve the therapeutic efficacy of radiotherapy and chemotherapy, multiple conjunctive modalities have been proposed, which include the targeting of components of the tumour microenvironment inhibiting tumour spread and anti-therapeutic pathways, increasing the oxygen content within the tumour to revert the hypoxic nature of the malignancy, improving the local dose deposition with metal nanoparticles, and the restriction of the cell cycle within radiosensitive phases. The tumour microenvironment is largely responsible for inhibiting nanoparticle capture within the tumour itself and improving resistance to various forms of cancer therapy. In this review, we discuss the current literature surrounding the administration of molecular and nanoparticle therapeutics, their pharmacokinetics, and contrasting mechanisms of action. The review aims to demonstrate the advancements in the field of conjugated nanomaterials and radiotherapeutics targeting, inhibiting, or bypassing the tumour microenvironment to promote further research that can improve treatment outcomes and toxicity rates.

Diagnostic accuracy of intravoxel incoherent motion (IVIM) and dynamic contrast-enhanced (DCE) MRI to differentiate benign from malignant breast lesions: A systematic review and meta-analysis

PURPOSE

Magnetic resonance imaging (MRI) can reduce the need for unnecessary invasive diagnostic tests by nearly half. In this meta-analysis, we investigated the diagnostic accuracy of intravoxel incoherent motion modeling (IVIM) and dynamic contrast-enhanced (DCE) MRI in differentiating benign from malignant breast lesions.

METHOD

We systematically searched PubMed, EMBASE, and Scopus. We included English articles reporting diagnostic accuracy for both sequences in differentiating benign from malignant breast lesions. Articles were assessed by quality assessment of diagnostic accuracy studies-2 (QUADAS-2) questionnaire. We used a bivariate effects model for standardized mean difference (SMD) analysis and diagnostic test accuracy analysis.

RESULTS

Ten studies with 537 patients and 707 (435 malignant and 272 benign) lesions were included. The D, f, Ktrans, and Kep mean values significantly differ between benign and malignant lesions. The pooled sensitivity (95 % confidence interval) and specificity were 86.2 % (77.9 %-91.7 %) and 70.3 % (56.5 %-81.1 %) for IVIM, and 93.8 % (85.3 %-97.5 %) and 68.1 % (52.7 %-80.4 %) for DCE, respectively. Combined IVIM and DCE depicted the highest area under the curve of 0.94, with a sensitivity and specificity of 91.8 % (82.8 %-96.3 %) and 87.6 % (73.8 %-94.7 %), respectively.

CONCLUSIONS

Combined IVIM and DCE had the highest diagnostic accuracy, and multiparametric MRI may help reduce unnecessary benign breast biopsy.

Small bowel imaging in inflammatory bowel disease: updates for 2023

INTRODUCTION

Cross-sectional imaging techniques including MR and CT enterography and ultrasound are integral to Crohn's disease management, accurate, responsive, and well tolerated. They assess the full thickness of the bowel wall, perienteric environment, and distant complications. As we strive toward tighter disease control, imaging's role will expand further with transmural healing becoming an increasingly important therapeutic target.

AREAS COVERED

MEDLINE and Web of Science were searched from 2012 to 2023 inclusive. We review the evidence for cross-sectional imaging in assessing disease activity, phenotyping, and therapeutic response assessment. Emerging novel imaging applications such as quantifying enteric motility and fibrosis, prognostication, and potential utility of artificial intelligence will be covered. Recent international consensus statements highlight the need for standardized imaging reporting and definitions of transmural healing and remission. We will discuss how recent advances may be best integrated into patient care and highlight key outstanding research questions.

EXPERT OPINION

Cross-sectional imaging is established in Crohn's disease management. Research emphasis should be placed on optimal integration of imaging modalities in clinical care pathways, workforce training, definitions, and evidence for use of imaging based therapeutic targets such as transmural healing, better phenotyping of stricturing disease, and developing novel techniques, including integration of artificial intelligence.