Gadolinium Retention and Toxicity-An Update

Anthropogenic impact of rare earth elements on groundwater and surface water in the watershed of the largest freshwater lake in China

Limited knowledge exists regarding the potential risks associated with anthropogenic release of rare earth elements (REEs) in the environment. This study aimed to investigate REE signatures in the watershed Poyang Lake, the largest freshwater lake in China. Samples of surface water, wastewater, and groundwater were collected from five rivers discharging into the lake. Results revealed wastewater from wastewater treatment plants contained total REE concentrations from 231 to 904 μg/L, exceeding those found in surface water (0.4 to 1.3 μg/L) and groundwater (0.5 to 416 μg/L). Samples with elevated REE were found in Ca-Mg-Cl/SO4 type waters and exhibited an 18OD deviation from local meteoric water line. Wastewater exhibited a higher positive Gd anomaly compared to surface water and groundwater, attributed to anthropogenic input of Gd (Gdanth). The determined Gdanth concentration ranged from 0.04 to 0.21 μg/L, and from 0.06 to 0.37 μg/L, accounting for 4 % to 21 % and 49 % to 84 % of total Gd concentrations in groundwater and surface water, respectively. Gdanth concentration in wastewater (0.19 to 0.43 μg/L) remained constant in effluent after wastewater treatment. Surface water displayed relatively complex normalized REE patterns influenced by anthropogenic activities and natural processes (weathering and complexation), while groundwater exhibited heavy REEs enrichment, due to carbonate solution complexation. Additionally, Gdanth concentration showed a positive correlation with ΣREE, Pb, Ni, and Co concentrations in groundwater, indicating a good pollution tracing potential. Health risk assessment using the hazard quotient (HQ) suggested higher HQGd values in groundwater compared to surface water. Residents in the eastern part of Poyang Lake were found to face higher risks associated with Gd in groundwater compared to the western part, with infants and children at greater risk than adult males and females. These findings offer valuable insights into environmental behavior and health risks of REEs in aquatic systems impacted by human activities.

3D quantitative myocardial perfusion imaging with hyperpolarized HP001(bis-1,1-(hydroxymethyl)-[1-13C]cyclopropane-d8): Application of gradient echo and balanced SSFP sequences

PURPOSE

This study aims to show the viability of conducting three-dimensional (3D) myocardial perfusion quantification covering the entire heart using both GRE and bSSFP sequences with hyperpolarized HP001.

METHODS

A GRE sequence and a bSSFP sequence, both with a stack-of-spirals readout, were designed and applied to three pigs. The images were reconstructed using  13 $$ {}^{13} $$ C coil sensitivity maps measured in a phantom experiment. Perfusion was quantified using a constrained decomposition method, and the estimated rest/stress perfusion values from  13 $$ {}^{13} $$ C GRE/bSSFP and Dynamic contrast-enhanced MRI (DCE-MRI) were individually analyzed through histograms and the mean perfusion values were compared with reference values obtained from PET(  15 $$ {}^{15} $$ O-water). The Myocardial Perfusion Reserve Index (MPRI) was estimated for  13 $$ {}^{13} $$ C GRE/bSSFP and DCE-MRI and compared with the reference values.

RESULTS

Perfusion values, estimated by both DCE and  13 $$ {}^{13} $$ C MRI, were found to be lower than reference values. However, DCE-MRI's estimated perfusion values were closer to the reference values than those obtained from  13 $$ {}^{13} $$ C MRI. In the case of MPRI estimation, the  13 $$ {}^{13} $$ C estimated MPRI values (GRE/bSSFP: 2.3/2.0) more closely align with the literature value (around 3) than the DCE estimated MPRI value (1.6).

CONCLUSION

This study demonstrated the feasibility of 3D whole-heart myocardial perfusion quantification using hyperpolarized HP001 with both GRE and bSSFP sequences. The  13 $$ {}^{13} $$ C perfusion measurements underestimated perfusion values compared to the  15 $$ {}^{15} $$ O PET literature value, while the  13 $$ {}^{13} $$ C estimated MPRI value aligned better with the literature. This preliminary result indicates  13 $$ {}^{13} $$ C imaging may more accurately estimate MPRI values compared to DCE-MRI.

Enhancing organ and vascular contrast in preclinical ultra-low field MRI using superparamagnetic iron oxide nanoparticles

Superparamagnetic iron oxide nanoparticles (SPIONs) are characterized by their exceptional susceptibility and relaxivity at ultra-low field (ULF) regimes, make them a promising contrast agent (CA) for ULF MRI. Despite their distinct advantages, the translation of these properties into clinically valuable image contrast in ULF MRI remains underexplored. In this study, we investigate the use of SPIONs to generate in vivo MRI contrast at 6.5 mT within the organs and vascular system of rodents. This investigation includes comprehensive SPION characterization and phantom imaging experiments to validate the utility of SPIONs to produce positive image contrast and to facilitate phase-sensitive imaging at ULF. Optimized balanced steady-state free precession (bSSFP) and spoiled gradient echo (SPGR) MRI sequences are used to generate in vivo contrast by leveraging the distinctive properties of SPIONs at ULF. Imaging studies in rodents reveal positive organ contrast attainable in magnitude images, and MRI phase maps can be used to visualize the vascular system. This work demonstrates the effectiveness of SPIONs in enhancing preclinical organ and vascular imaging at ULF; it bridges the gap between the study of the distinctive physical properties of SPIONs and the demonstration of in vivo image contrast.

Prognostic significance of paramagnetic rim lesions in multiple sclerosis: A systematic review

The diagnostic potential of paramagnetic rim lesions (PRLs) has been previously established; however, the prognostic significance of these lesions has not previously been consistently described. This study aimed to establish the prognostic role of PRLs in MS with respect to the Expanded Disability Status Scale (EDSS) and rates of disability progression. Databases of PubMed, EMBASE, Scopus and reference lists of selected articles were searched up to 29/04/2023. The review was conducted in accordance with PRISMA guidelines and was registered prospectively on PROSPERO (CRD42023422052). 7 studies were included in the final review. All of the eligible studies found that patients with PRLs tend to have higher baseline EDSS scores. Longitudinal assessments revealed greater EDSS progression in patients with PRLs over time in most studies. However, the effect of location of PRLs within the central nervous system were not assessed across the studies. Only one study investigated progression independent of relapse activity (PIRA) and showed that this clinical entity occurred in a greater proportion in patients with PRLs. This review supports PRLs as a predictor of EDSS progression. This measure has widespread applicability, however further multicentre studies are needed. Future research should explore the impact of PRLs on silent disability, PIRA, take into account different MS phenotypes and the topography of PRLs in prognosis.

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.

A stable, highly concentrated fluorous nanoemulsion formulation for in vivo cancer imaging via 19F-MRI

Magnetic resonance imaging (MRI) is a routine diagnostic modality in oncology that produces excellent imaging resolution and tumor contrast without the use of ionizing radiation. However, improved contrast agents are still needed to further increase detection sensitivity and avoid toxicity/allergic reactions associated with paramagnetic metal contrast agents, which may be seen in a small percentage of the human population. Fluorine-19 (19F)-MRI is at the forefront of the developing MRI methodologies due to near-zero background signal, high natural abundance of 100%, and unambiguous signal specificity. In this study, we have developed a colloidal nanoemulsion (NE) formulation that can encapsulate high volumes of the fluorous MRI tracer, perfluoro-[15-crown-5]-ether (PFCE) (35% v/v). These nanoparticles exhibit long-term (at least 100 days) stability and high PFCE loading capacity in formulation with our semifluorinated triblock copolymer, M2F8H18. With sizes of approximately 200 nm, these NEs enable in vivo delivery and passive targeting to tumors. Our diagnostic formulation, M2F8H18/PFCE NE, yielded in vivo 19F-MR images with a high signal-to-noise ratio up to 100 in a tumor-bearing mouse model at clinically relevant scan times. M2F8H18/PFCE NE circulated stably in the vasculature, accumulated in high concentration of an estimated 4-9 × 1017 19F spins/voxel at the tumor site, and cleared from most organs over the span of 2 weeks. Uptake by the mononuclear phagocyte system to the liver and spleen was also observed, most likely due to particle size. These promising results suggest that M2F8H18/PFCE NE is a favorable 19F-MR diagnostic tracer for further development in oncological studies and potential clinical translation.

Prostate MRI for the detection of clinically significant prostate cancer: Update and future directions

PURPOSE OF REVIEW

In recent decades, there has been an increasing role for magnetic resonance imaging (MRI) in the detection of clinically significant prostate cancer (csPC). The purpose of this review is to provide an update and outline future directions for the role of MRI in the detection of csPC.

RECENT FINDINGS

In diagnosing clinically significant prostate cancer pre-biopsy, advances include our understanding of MRI-targeted biopsy, the role of biparametric MRI (non-contrast) and changing indications, for example the role of MRI in screening for prostate cancer. Furthermore, the role of MRI in identifying csPC is maturing, with emphasis on standardization of MRI reporting in active surveillance (PRECISE), clinical staging (EPE grading, MET-RADS-P) and recurrent disease (PI-RR, PI-FAB). Future directions of prostate MRI in detecting csPC include quality improvement, artificial intelligence and radiomics, positron emission tomography (PET)/MRI and MRI-directed therapy.

SUMMARY

The utility of MRI in detecting csPC has been demonstrated in many clinical scenarios, initially from simply diagnosing csPC pre-biopsy, now to screening, active surveillance, clinical staging, and detection of recurrent disease. Continued efforts should be undertaken not only to emphasize the reporting of prostate MRI quality, but to standardize reporting according to the appropriate clinical setting.

Breast imaging with an ultra-low field MRI scanner: a pilot study

Breast cancer screening is necessary to reduce mortality due to undetected breast cancer. Current methods have limitations, and as a result many women forego regular screening. Magnetic resonance imaging (MRI) can overcome most of these limitations, but access to conventional MRI is not widely available for routine annual screening. Here, we used an MRI scanner operating at ultra-low field (ULF) to image the left breasts of 11 women (mean age, 35 years ±13 years) in the prone position. Three breast radiologists reviewed the imaging and were able to discern the breast outline and distinguish fibroglandular tissue (FGT) from intramammary adipose tissue. Additionally, the expert readers agreed on their assessment of the breast tissue pattern including fatty, scattered FGT, heterogeneous FGT, and extreme FGT. This preliminary work demonstrates that ULF breast MRI is feasible and may be a potential option for comfortable, widely deployable, and low-cost breast cancer diagnosis and screening.

Dynamic 2-deoxy-D-glucose-enhanced multispectral optoacoustic tomography for assessing metabolism and vascular hemodynamics of breast cancer

Clinical tools for measuring tumor vascular hemodynamics, such as dynamic contrast-enhanced MRI, are clinically important to assess tumor properties. Here we explored the use of multispectral optoacoustic tomography (MSOT), which has a high spatial and temporal resolution, to measure the intratumoral pharmacokinetics of a near-infrared-dye-labeled 2-Deoxyglucose, 2-DG-800, in orthotropic 2-LMP breast tumors in mice. As uptake of 2-DG-800 is dependent on both vascular properties, and glucose transporter activity - a widely-used surrogate for metabolism, we evaluate hemodynamics of 2-DG-MP by fitting the dynamic MSOT signal of 2-DG-800 into two-compartment models including the extended Tofts model (ETM) and reference region model (RRM). We showed that dynamic 2-DG-enhanced MSOT (DGE-MSOT) is powerful in acquiring hemodynamic rate constants, including Ktrans and Kep, via systemically injecting a low dose of 2-DG-800 (0.5 µmol/kg b.w.). In our study, both ETM and RRM are efficient in deriving hemodynamic parameters in the tumor. Area-under-curve (AUC) values (which correlate to metabolism), and Ktrans and Kep values, can effectively distinguish tumor from muscle. Hemodynamic parameters also demonstrated correlations to hemoglobin, oxyhemoglobin, and blood oxygen level (SO2) measurements by spectral unmixing of the MSOT data. Together, our study for the first time demonstrated the capability of DGE-MSOT in assessing vascular hemodynamics of tumors.

Comparing biparametric to multiparametric MRI in the diagnosis of clinically significant prostate cancer in biopsy-naive men (PRIME): a prospective, international, multicentre, non-inferiority within-patient, diagnostic yield trial protocol

INTRODUCTION

Prostate MRI is a well-established tool for the diagnostic work-up for men with suspected prostate cancer (PCa). Current recommendations advocate the use of multiparametric MRI (mpMRI), which is composed of three sequences: T2-weighted sequence (T2W), diffusion-weighted sequence (DWI) and dynamic contrast-enhanced sequence (DCE). Prior studies suggest that a biparametric MRI (bpMRI) approach, omitting the DCE sequences, may not compromise clinically significant cancer detection, though there are limitations to these studies, and it is not known how this may affect treatment eligibility. A bpMRI approach will reduce scanning time, may be more cost-effective and, at a population level, will allow more men to gain access to an MRI than an mpMRI approach.

METHODS

Prostate Imaging Using MRI±Contrast Enhancement (PRIME) is a prospective, international, multicentre, within-patient diagnostic yield trial assessing whether bpMRI is non-inferior to mpMRI in the diagnosis of clinically significant PCa. Patients will undergo the full mpMRI scan. Radiologists will be blinded to the DCE and will initially report the MRI using only the bpMRI (T2W and DWI) sequences. They will then be unblinded to the DCE sequence and will then re-report the MRI using the mpMRI sequences (T2W, DWI and DCE). Men with suspicious lesions on either bpMRI or mpMRI will undergo prostate biopsy. The main inclusion criteria are men with suspected PCa, with a serum PSA of ≤20 ng/mL and without prior prostate biopsy. The primary outcome is the proportion of men with clinically significant PCa detected (Gleason score ≥3+4 or Gleason grade group ≥2). A sample size of at least 500 patients is required. Key secondary outcomes include the proportion of clinically insignificant PCa detected and treatment decision.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the National Research Ethics Committee West Midlands, Nottingham (21/WM/0091). Results of this trial will be disseminated through peer-reviewed publications. Participants and relevant patient support groups will be informed about the results of the trial.

TRIAL REGISTRATION NUMBER

NCT04571840.

A Novel Protein for the Bioremediation of Gadolinium Waste

Several hundreds of tons of gadolinium-based contrast agents (GBCAs) are being dumped into the environment every year. Although macrocyclic GBCAs exhibit superior stability compared to their linear counterparts, we have found that the structural integrity of chelates are susceptible to ultraviolet light, regardless of configuration. In this study, we present a synthetic protein termed GLamouR that binds and reports gadolinium in an intensiometric manner. We then explore the extraction of gadolinium from GBCA-spiked artificial urine samples and investigate if the low picomolar concentrations reported in gadolinium-contaminated water sources pose a barrier for bioremediation. Based on promising results, we anticipate GLamouR can be used for detecting and mining REEs beyond gadolinium as well and hope to expand the biological toolbox for such applications.

Predictive value of cardiac magnetic resonance mechanical parameters for myocardial fibrosis in hypertrophic cardiomyopathy with preserved left ventricular ejection fraction

Objective

Myocardial fibrosis leads to systolic dysfunction in hypertrophic cardiomyopathy (HCM) patients. This study aims to investigate the relationship between cardiac magnetic resonance mechanical parameters for evaluating the left ventricular function in HCM with preserved left ventricular ejection fraction (LVEF ≥50%) and the association between myocardial fibrosis defined by late gadolinium enhancement (LGE).

Methods

This study was a retrospective analysis of CMR images of 93 patients with HCM with preserved ejection fraction (HCMpEF) and 96 controls diagnosed by cardiac magnetic resonance (CMR) at our hospital from July 2019 to January 2022. The myocardial contraction fraction (MCF) was calculated, and myocardial mechanical parameters, including global myocardial longitudinal strain (GLS), circumferential strain (GLS), and myocardial strain (GLS), were obtained by tissue tracking and LGE quantitative modules of dedicated software, respectively. The correlation between myocardial strain and LGE was analyzed, and a multivariate logistic regression model was developed to discuss the risk predictors of LGE.

Results

Compared to the control group, the left ventricular mechanical parameters GLS (-13.90 ± 3.80% versus -18.20 ± 2.10%, p < 0.001), GCS (-16.62 ± 3.50% versus -18.4 ± 2.69%, p < 0.001), GRS (28.99 ± 10.38% versus 33.02 ± 6.25%, p < 0.01), and MCF (64 ± 16% versus 99 ± 18%, p < 0.001) were found significantly lower in HCM group. Moreover, even in LGE-negative HCM patients, GLS (-16.3 ± 3.9%) and MCF (78 ± 19%) were significantly lower compared to the control group. Left ventricular GLS [OR = 1.61, (1.29, 2.02), p = 0.001] and MCF [OR = 0.90, (0.86, 0.94), p = 0.001] independently predicted myocardial late gadolinium enhancement (LGE).

Conclusion

In participants of HCM with preserved ejection fraction, the early onset of reduced left ventricular GLS and MCF in patients with HCMpEF may provide new evidence for evaluating impaired myocardial systolic function. The reduction of myocardial mechanical indexes may reflect the presence and extent of myocardial fibrosis, and the more significant the reduction, the more severe the myocardial fibrosis; GLS and MCF may be ideal predictors for LGE.

Gadolinium based contrast agents (GBCAs): Uniqueness, aquatic toxicity concerns, and prospective remediation

The current toxicity concerns of gadolinium-based contrast agents (GBCAs) have birthed the need to regulate and, sometimes restrict its clinical administration. However, tolerable concentration levels of Gd in the water sector have not been set. Therefore, the detection and speedy increase of the anthropogenic Gd-GBCAs in the various water bodies, including those serving as the primary source of drinking water for adults and children, is perturbing. Nevertheless, the strongly canvassed risk-benefit considerations and superior uniqueness of GBCAs compared to the other ferromagnetic metals guarantees its continuous administration for Magnetic resonance imaging (MRI) investigations regardless of the toxicity concerns. Unfortunately, findings have shown that both the advanced and conventional wastewater treatment processes do not satisfactorily remove GBCAs but rather risk transforming the chelated GBCAs to their free ionic metal (Gd ³⁺) through inadvertent degradation processes. This unintentional water processing-induced GBCA dechelation leads to the intricate  pathway for unintentional human intake of Gd ion. Hence exposure to its probable ecotoxicity and several reported inimical effects on human health such as; digestive symptoms, twitching or weakness, cognitive flu, persistent skin diseases, body pains, acute renal and non-renal adverse reactions, chronic skin, and eyes changes. This work proposed an economical and manageable remediation technique for the potential remediation of Gd-GBCAs in wastewater, while a precautionary limit for Gd in public water and commercial drinks is advocated.

Encephalopathy after unintentional intrathecal gadolinium: A letter to the editor

Objective

Raise awareness of gadolinium encephalopathy, a rare cause of neurological symptoms.

Setting

An L5-S1 interlaminar epidural steroid injection (IL-ESI) was performed with a gadolinium-based contrast agent (GBCA) due to the patient's history of allergic reaction to iodine-based contrast agents.

Discussion

Several hours after administration of GBCA, the patient had nausea and vomiting with altered mental status. Patient was treated with dexamethasone IV, and was discharged on day 2. Patient had no residual deficits at follow-up two weeks later. Current literature shows that caution should be used to prevent inadvertent intrathecal GBCA, and doses >2.0 mmols are associated with serious adverse effects, including death.

Conclusions

Intrathecal administration of GBCAs should be limited to less than 0.5 mmol. If adverse effects are experienced, IV steroids should be administered as soon as possible, and a CSF drain should be considered.

Deep learning of MRI contrast enhancement for mapping cerebral blood volume from single-modal non-contrast scans of aging and Alzheimer's disease brains

While MRI contrast agents such as those based on Gadolinium are needed for high-resolution mapping of brain metabolism, these contrast agents require intravenous administration, and there are rising concerns over their safety and invasiveness. Furthermore, non-contrast MRI scans are more commonly performed than those with contrast agents and are readily available for analysis in public databases such as the Alzheimer's Disease Neuroimaging Initiative (ADNI). In this article, we hypothesize that a deep learning model, trained using quantitative steady-state contrast-enhanced structural MRI datasets, in mice and humans, can generate contrast-equivalent information from a single non-contrast MRI scan. The model was first trained, optimized, and validated in mice, and was then transferred and adapted to humans. We observe that the model can substitute for Gadolinium-based contrast agents in approximating cerebral blood volume, a quantitative representation of brain activity, at sub-millimeter granularity. Furthermore, we validate the use of our deep-learned prediction maps to identify functional abnormalities in the aging brain using locally obtained MRI scans, and in the brain of patients with Alzheimer's disease using publicly available MRI scans from ADNI. Since it is derived from a commonly-acquired MRI protocol, this framework has the potential for broad clinical utility and can also be applied retrospectively to research scans across a host of neurological/functional diseases.

Effects of gadodiamide and gadoteric acid on lung tissue: A comparative study

We set out to investigate the effects of gadodiamide and gadoteric acid, used for magnetic resonance imaging, on the lungs. In this study, 32 male Sprague Dawley rats were used. These were allocated into four groups; The first group (control) was untreated. The second group received isotonic saline on the first and fourth days of the week for 5 weeks. Following the same schedule, the third and fourth groups received a total of 2 mg/kg gadodiamide and gadoteric acid, respectively, in place of saline. The alveolar Wall thickness was evaluated. Gadodiamide and gadoteric acid significantly increased the numbers of collagen-3 and caspase-3 positive cells in the lung tissue (p < 0.05). In addition, these two substances increased the alveolar Wall thickness (p < 0.05). Furthermore, they increased the levels of malondialdehyde and glutathione (p < 0.05). This study demonstrates that both linear and macrocyclic contrast agents are toxic for the lungs in rats.

Biparametric magnetic resonance imaging assessment for detection of muscle-invasive bladder cancer: a systematic review and meta-analysis

OBJECTIVES

To investigate if removing DCE from the Vesical Imaging Reporting and Data System (VI-RADS) influences the diagnostic accuracy of muscle-invasive bladder cancer (MIBC). We also explored using different reference standards on the MRI diagnostic performance.

METHODS

We searched the Cochrane Library, Embase, and PubMed databases to June 26, 2021. Pooled biparametric MRI (bpMRI, T2WI+DWI) and multiparametric MRI (mpMRI, T2WI+DWI+DCE) sensitivities and specificities and the diagnostic performances of these methods for MIBC were compared using different reference standards.

RESULTS

Seventeen studies with 2344 patients were finally included, of which 7 studies, including 1041 patients, reported the diagnostic performance of bpMRI. VI-RADS showed sensitivities and specificities of 0.91 (95% CI 0.87-0.94) and 0.86 (95% CI 0.77-0.91) at cutoff scores of 3, and 0.85 (95% CI 0.77-0.90) and 0.93 (95% CI 0.89-0.96) at cutoff scores of 4. BpMRI showed sensitivities and specificities of 0.90 (95% CI 0.69-0.97) and 0.90 (95% CI 0.81-0.95), and 0.84 (95% CI 0.78-0.88) and 0.97 (95% CI 0.87-0.99), respectively, for cutoff scores of 3 and 4. The sensitivities of bpMRI vs mpMRI for MIBC were not significantly different, but bpMRI was more specific than mpMRI at cutoff scores of 3 (p = 0.02) and 4 (p = 0.02). The VI-RADS studies using primary transurethral resection of bladder tumors (TURBT) as the reference standard had significantly higher sensitivities (p < 0.001) than those using secondary TURBT or radical cystectomy as the reference.

DATA CONCLUSION

BpMRI and conventional VI-RADS had similar diagnostic efficacies for MIBC. Since MRI overestimated MIBC diagnoses using primary TURBT as the reference standard, we recommend using secondary TURBT as the reference standard.

KEY POINTS

• Biparametric MRI without DCE had similar diagnostic efficacies for MIBC compared with conventional VI-RADS. • The sensitivity of VI-RADS was overestimated when referring to the primary TURBT results. • Biparametric MRI comprised of T2WI and DWI could be used for detecting MIBC in clinical practice.

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

Background

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

Purpose

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

Study type

Cross‐sectional cohort toxicity study.

Animal Model

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

Field Strength

A 9.4 T and fast spin echo sequence.

Assessment

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

Statistical Tests

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

Results

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

Data Conclusion

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

Evidence Level

1

Technical Efficacy

Stage 2

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

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

Synthetic magnetic resonance imaging for primary prostate cancer evaluation: Diagnostic potential of a non-contrast-enhanced bi-parametric approach enhanced with relaxometry measurements

Purpose

Bi-parametric magnetic resonance imaging (bpMRI) with diffusion-weighted images has wide utility in diagnosing clinically significant prostate cancer (csPCa). However, bpMRI yields more false-negatives for PI-RADS category 3 lesions than multiparametric (mp)MRI with dynamic-contrast-enhanced (DCE)-MRI. We investigated the utility of synthetic MRI with relaxometry maps for bpMRI-based diagnosis of csPCa.

Methods

One hundred and five treatment-naïve patients who underwent mpMRI and synthetic MRI before prostate biopsy for suspected PCa between August 2019 and December 2020 were prospectively included. Three experts and three basic prostate radiologists evaluated the diagnostic performance of conventional bpMRI and synthetic bpMRI for csPCa. PI-RADS version 2.1 category 3 lesions were identified by consensus, and relaxometry measurements (T1-value, T2-value, and proton density [PD]) were performed. The diagnostic performance of relaxometry measurements for PI-RADS category 3 lesions in peripheral zone was compared with that of DCE-MRI. Histopathological evaluation results were used as the reference standard. Statistical analysis was performed using the areas under the receiver operating characteristic curve (AUC) and McNemar test.

Results

In 102 patients without significant MRI artefacts, the diagnostic performance of conventional bpMRI was not significantly different from that of synthetic bpMRI for all readers (p = 0.11–0.79). The AUCs of the combination of T1-value, T2-value, and PD (T1 + T2 + PD) for csPCa in peripheral zone for PI-RADS category 3 lesions were 0.85 for expert and 0.86 for basic radiologists, with no significant difference between T1 + T2 + PD and DCE-MRI for both expert and basic radiologists (p = 0.29–0.45).

Conclusion

Synthetic MRI with relaxometry maps shows promise for contrast media-free evaluation of csPCa.

•

Diagnostic performances of synthetic bpMRI and conventional bpMRI are comparable for primary PCa

•

Diagnostic performance of synthetic MRI variables are similar to that of DCE-MRI for csPCa in PZ

•

Synthetic bpMRI shows potential as a contrast agent-free method for primary PCa

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.

Endogenous T1ρ cardiovascular magnetic resonance in hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is characterized by increased left ventricular wall thickness, cardiomyocyte hypertrophy, and fibrosis. Adverse cardiac risk characterization has been performed using late gadolinium enhancement (LGE), native T1, and extracellular volume (ECV). Relaxation time constants are affected by background field inhomogeneity. T1ρ utilizes a spin-lock pulse to decrease the effect of unwanted relaxation. The objective of this study was to study T1ρ as compared to T1, ECV, and LGE in HCM patients.

METHODS

HCM patients were recruited as part of the Novel Markers of Prognosis in Hypertrophic Cardiomyopathy study, and healthy controls were matched for comparison. In addition to cardiac functional imaging, subjects underwent T1 and T1ρ cardiovascular magnetic resonance imaging at short-axis positions at 1.5T. Subjects received gadolinium and underwent LGE imaging 15-20 min after injection covering the entire heart. Corresponding basal and mid short axis LGE slices were selected for comparison with T1 and T1ρ. Full-width half-maximum thresholding was used to determine the percent enhancement area in each LGE-positive slice by LGE, T1, and T1ρ. Two clinicians independently reviewed LGE images for presence or absence of enhancement. If in agreement, the image was labeled positive (LGE + +) or negative (LGE --); otherwise, the image was labeled equivocal (LGE + -).

RESULTS

In 40 HCM patients and 10 controls, T1 percent enhancement area (Spearman's rho = 0.61, p < 1e-5) and T1ρ percent enhancement area (Spearman's rho = 0.48, p < 0.001e-3) correlated with LGE percent enhancement area. T1 and T1ρ percent enhancement areas were also correlated (Spearman's rho = 0.28, p = 0.047). For both T1 and T1ρ, HCM patients demonstrated significantly longer relaxation times compared to controls in each LGE category (p < 0.001 for all). HCM patients also showed significantly higher ECV compared to controls in each LGE category (p < 0.01 for all), and LGE -- slices had lower ECV than LGE + + (p = 0.01).

CONCLUSIONS

Hyperenhancement areas as measured by T1ρ and LGE are moderately correlated. T1, T1ρ, and ECV were elevated in HCM patients compared to controls, irrespective of the presence of LGE. These findings warrant additional studies to investigate the prognostic utility of T1ρ imaging in the evaluation of HCM patients.

Modified Predictive Model and Nomogram by Incorporating Prebiopsy Biparametric Magnetic Resonance Imaging With Clinical Indicators for Prostate Biopsy Decision Making

Purpose

The purpose of this study is to explore the value of combining bpMRI and clinical indicators in the diagnosis of clinically significant prostate cancer (csPCa), and developing a prediction model and Nomogram to guide clinical decision-making.

Methods

We retrospectively analyzed 530 patients who underwent prostate biopsy due to elevated serum prostate specific antigen (PSA) levels and/or suspicious digital rectal examination (DRE). Enrolled patients were randomly assigned to the training group (n = 371, 70%) and validation group (n = 159, 30%). All patients underwent prostate bpMRI examination, and T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI) sequences were collected before biopsy and were scored, which were respectively named T2WI score and DWI score according to Prostate Imaging Reporting and Data System version 2 (PI-RADS v.2) scoring protocol, and then PI-RADS scoring was performed. We defined a new bpMRI-based parameter named Total score (Total score = T2WI score + DWI score). PI-RADS score and Total score were separately included in the multivariate analysis of the training group to determine independent predictors for csPCa and establish prediction models. Then, prediction models and clinical indicators were compared by analyzing the area under the curve (AUC) and decision curves. A Nomogram for predicting csPCa was established using data from the training group.

Results

In the training group, 160 (43.1%) patients had prostate cancer (PCa), including 128 (34.5%) with csPCa. Multivariate regression analysis showed that the PI-RADS score, Total score, f/tPSA, and PSA density (PSAD) were independent predictors of csPCa. The prediction model that was defined by Total score, f/tPSA, and PSAD had the highest discriminatory power of csPCa (AUC = 0.931), and the diagnostic sensitivity and specificity were 85.1% and 87.5%, respectively. Decision curve analysis (DCA) showed that the prediction model achieved an optimal overall net benefit in both the training group and the validation group. In addition, the Nomogram predicted csPCa revealed good estimation when compared with clinical indicators.

Conclusion

The prediction model and Nomogram based on bpMRI and clinical indicators exhibit a satisfactory predictive value and improved risk stratification for csPCa, which could be used for clinical biopsy decision-making.

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.

Circulating levels of tight junction proteins in multiple sclerosis: Association with inflammation and disease activity before and after disease modifying therapy

BACKGROUND

Tight junction proteins contribute to maintenance of epithelial and endothelial barriers such as the intestinal barrier and the blood brain barrier (BBB). Increased permeability of these barriers has been linked to disease activity in MS and there is currently a lack of easily accessible biomarkers predicting disease activity in MS.

AIM

To investigate whether levels of circulating tight junction proteins occludin and zonula occludens-1 (ZO-1) are associated with biomarkers of inflammation and disease activity; and to determine whether they could serve as clinical biomarkers.

METHODS

We prospectively included 72 newly diagnosed patients with relapsing remitting MS or clinically isolated syndrome with no prior disease modifying therapy (DMT) use and 50 healthy controls (HCs). Patients were followed with blood samples, 3 tesla MRI, and clinical evaluation for 12 months. Occludin, ZO-1, calprotectin and soluble urokinase-type plasminogen activator receptor (suPAR) were measured by ELISA; serum neurofilament light (NfL) and IL-6 by single-molecule array (SIMOA). The mRNA expression of IFNG, IL1R1, IL10, IL1B, ARG1 and TNF was measured by quantitative real time polymerase chain reaction (qPCR) in whole blood.

RESULTS

Plasma occludin levels were higher in MS patients compared with HCs. After 12 months on DMT, occludin levels were reduced by approximately 25% irrespective of 1st or 2nd line DMT (p<0.001). Furthermore, NfL and calprotectin levels were significantly reduced by 31% and 29%, respectively. Occludin and ZO-1 did not correlate with biomarkers of inflammation and did not predict disease activity at baseline or after 12 months.

CONCLUSIONS

Higher levels of occludin suggest an increased permeability of the BBB and/or the intestinal barrier in MS patients. The reduction of occludin after 12 months on DMTs might reflect repair of these barriers upon treatment. However, plasma levels of ZO-1 and occludin could not predict clinical or MRI disease activity as determined by regression and ROC-curve analysis. Our results do not indicate a clear clinically relevant role for circulating tight junction proteins as biomarkers of disease activity in MS and further investigations in larger cohorts are needed to clarify this issue.

Virtual non-contrast enhanced magnetic resonance imaging (VNC-MRI)

PURPOSE

Application of contrast agents (CA) is widely used in various clinical fields like oncology. Similar to approaches used in computed tomography, virtual non-contrast enhanced (VNC) images can be generated with the goal to supersede true non-contrast enhanced (TNC) images.

METHODS

In MRI a T1-mapping sequence with variable flip angle (VFA) was used to acquire two images with different image contrast at the same time. To generate VNC images postprocessing based on this technique, an image-space based material decomposition algorithm was used. The inverse of a sensitivity matrix, consisting of intensity values for both VFA images and every material respectively, was used to determine the three material fractions and to calculate the final VNC images. The technique was tested on a 3 T scanner using a phantom and two in-vivo scans of patients with glioma and glioblastoma respectively. In all these cases the required six values were manually derived from the respective material or the background from both VFA images.

RESULTS

Postprocessing results of the phantom show that the chosen materials can be separated and visualized individually and unwanted materials can be suppressed. In the VNC images of in-vivo scans the signal of the CA is removed successfully.

CONCLUSION

It was shown that VNC images that match the visual impression of the TNC images can be generated, resulting in possibly reduced scan times and avoided mismatches due to movement of the patient.

Contrast-enhanced ultrasound (CEUS) reliably rules out neoplasm in developmental renal pseudotumor

BACKGROUND

Renal pseudotumors appear as benign cortical hypertrophies and are typically assessed by contrast-enhanced computed tomography or magnetic resonance imaging to rule out malignancy.

PURPOSE

To investigate whether contrast-enhanced ultrasound (CEUS) can rule out renal neoplasm and thus potentially reduce cross-sectional imaging and further follow-up in these patients.

MATERIAL AND METHODS

Thirty-two patients with presumption of developmental renal pseudotumor on CEUS between June 2011 and July 2019 were retrospectively analyzed. All patients were examined with a standardized renal US protocol including B-mode, color-coded duplex sonography (CCDS), and CEUS by an experienced radiologist (EFSUMB level 3). Images were retrospectively interpreted in consensus by two highly experienced radiologists. Histopathological reports, cross-sectional imaging findings, and clinical course (treatment response, long-term imaging follow-up) were defined as standard of reference.

RESULTS

CEUS correctly identified 8/9 neoplastic lesions and missed one oncocytoma within the 32 included patients. Irregular vessel structure (88.9% vs. 13.0%, P = 0.007) and hyperenhancement (66.6% vs. 17.4%, P = 0.031) on CEUS were more common in neoplasm compared to developmental pseudotumors reaching statistical significance. Compared with the standard of reference, CEUS had 89% sensitivity (95% confidence interval [CI] 57-98), 96% specificity (95% CI 80-99), a positive predictive value of 89% (95% CI 57-98), and a negative predictive value of 96% (95% CI 79-99) for ruling out renal malignancy in developmental pseudotumors.

CONCLUSION

CEUS is a safe and fast method to rule out neoplasm in the diagnostic work-up of renal pseudotumors. In conjunction with B-mode and CCDS, CEUS has the potential to reduce further (invasive) diagnostic procedures.

MRI and muscle imaging for idiopathic inflammatory myopathies

Although idiopathic inflammatory myopathies (IIM) are a heterogeneous group of diseases nearly all patients display muscle inflammation. Originally, muscle biopsy was considered as the gold standard for IIM diagnosis. The development of muscle imaging led to revisiting not only the IIM diagnosis strategy but also the patients' follow-up. Different techniques have been tested or are in development for IIM including positron emission tomography, ultrasound imaging, ultrasound shear wave elastography, though magnetic resonance imaging (MRI) remains the most widely used technique in routine. Whereas guidelines on muscle imaging in myositis are lacking here we reviewed the relevance of muscle imaging for both diagnosis and myositis patients' follow-up. We propose recommendations about when and how to perform MRI on myositis patients, and we describe new techniques that are under development.

Usefulness of triggered non-contrast-enhanced magnetic resonance angiography in assessing lower extremity venous disease

Although venous duplex ultrasonography (USG) is reliable for diagnosing lower extremity venous disease (LEVD), cross-sectional imaging studies were usually required before intervention or surgery. Patients of LEVD with renal insufficiency usually restrict the use of contrast-enhanced imaging modalities. In seeking an alternative imaging solution for these patients, we explore the clinical utility of triggered angiography non-contrast-enhanced magnetic resonance imaging (TRANCE-MRI) in the assessment of LEVD.We collected data from patients presenting to a tertiary wound-care center with symptoms of LEVD from April 2017-November 2019. Each participant underwent baseline USG followed by TRANCE-MRI on a 1.5T MR scanner (Philips Ingenia, Philips Healthcare, Best, The Netherlands). Inter-rater reliability was measured using Cohen's kappa (κ).All 80 participants (mean age, 61.9 ± 14.8 years; 35 males, 45 females) were assessed and were classified into one of five disease groups, deep vein thrombosis (n = 38), venous static ulcer (n = 16), symptomatic varicose veins (n = 18), recurrent varicose veins (n = 3), and lymphoedema (n = 5). The inter-rater reliability between TRANCE-MRI and doppler USG showed substantial agreement (κ, 0.73). The sensitivity, specificity, and accuracy of TRANCE-MRI were 90.5%, 88.1%, and 88.8%, respectively. In 59 (73.8%) USG-negative patients, we were able to diagnose positive findings (deep venous thrombosis, n = 7; varicose veins, n = 15; lymphedema, n = 10; iliac vein compression with thrombosis, n = 6; external venous compression, n = 5; vena cava anomaly, n = 2; occult peripheral artery disease, n = 5; ccluded bypass graft, n = 1) by using TRANCE-MRI. Of these, 9 (15.3%) patients underwent additional vascular surgery based on positive TRANCE-MRI findings.TRANCE technique provides the limb's entire venous drainage in clear images without background contamination by associated arterial imaging. Additionally, simultaneous evaluation of bilateral lower extremities can help determine the lesion's exact site. Although TRANCE-MRI can provide MR arteriography and MR venography, we recommend performing only MR venography in symptomatic LEVD patients because the incidence of occult arterial disease is low.

Folic Acid Functionalized Carbon Dot/Polypyrrole Nanoparticles for Specific Bioimaging and Photothermal Therapy

Polypyrrole nanoparticles (PPy-NPs) with excellent near-infrared absorption are commonly used as photothermal therapy (PTT) agents; however, PTT using PPy-NPs has a limitation in that it is difficult to maximize their therapeutic effect because of the lack of specific targeting. In this study, to overcome the difficulty of targeting, folic acid functionalized carbon dots (FA-CDs) with bright green fluorescence properties were combined with carboxylated PPy-NPs via the EDC/NHS coupling reaction to yield a PTT imaging agent. The synthesized FA-CD/PPy-NPs with excellent photostability performed folate receptor (FR) positive HeLa cancer cell imaging by green fluorescence signals of FA-CDs and exhibited high cell viability (above 90%) even at 500 μg/mL. The viability of HeLa cells incubated with 200 μg/mL FA-CD/PPy-NPs was dramatically decreased to 25.02 ± 1.85% by NIR laser irradiation, through photothermal therapeutic effects of FA-CD/PPy-NPs with high photothermal conversion efficiency (η = 40.80 ± 1.54%). The cancer cell death by FA-CD/PPy-NPs was confirmed by fluorescence imaging of FA-CDs as well as live/dead cell staining assay (calcein-AM/PI). These results demonstrate that the FA-CD/PPy-NPs can be utilized as multifunctional theranostic agents for specific bioimaging and treatment of FR-positive cancer cells.

Machine learning phenotyping of scarred myocardium from cine in hypertrophic cardiomyopathy

AIMS

Cardiovascular magnetic resonance (CMR) with late-gadolinium enhancement (LGE) is increasingly being used in hypertrophic cardiomyopathy (HCM) for diagnosis, risk stratification, and monitoring. However, recent data demonstrating brain gadolinium deposits have raised safety concerns. We developed and validated a machine-learning (ML) method that incorporates features extracted from cine to identify HCM patients without fibrosis in whom gadolinium can be avoided.

METHODS AND RESULTS

An XGBoost ML model was developed using regional wall thickness and thickening, and radiomic features of myocardial signal intensity, texture, size, and shape from cine. A CMR dataset containing 1099 HCM patients collected using 1.5T CMR scanners from different vendors and centres was used for model development (n=882) and validation (n=217). Among the 2613 radiomic features, we identified 7 features that provided best discrimination between +LGE and -LGE using 10-fold stratified cross-validation in the development cohort. Subsequently, an XGBoost model was developed using these radiomic features, regional wall thickness and thickening. In the independent validation cohort, the ML model yielded an area under the curve of 0.83 (95% CI: 0.77-0.89), sensitivity of 91%, specificity of 62%, F1-score of 77%, true negatives rate (TNR) of 34%, and negative predictive value (NPV) of 89%. Optimization for sensitivity provided sensitivity of 96%, F2-score of 83%, TNR of 19% and NPV of 91%; false negatives halved from 4% to 2%.

CONCLUSION

An ML model incorporating novel radiomic markers of myocardium from cine can rule-out myocardial fibrosis in one-third of HCM patients referred for CMR reducing unnecessary gadolinium administration.

Variability in hair gadolinium concentrations among decedents who received gadolinium-based contrast agents

This study utilized laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to quantify gadolinium in the hair of autopsy cases that had received gadolinium-based contrast agents (GBCAs) before death. Consecutive autopsy cases were reviewed for GBCA injections and subjects who received a single type of GBCA in the year before death were included. Hair samples were analyzed using LA-ICP-MS as a line scan technique and parameters were optimized to maximize instrument sensitivity, accuracy, and precision. Linear regression analyses between hair measures and gadolinium dose were executed. LA-ICP-MS analysis produced a time-resolved record of GCBA exposure, with the position of the gadolinium peak maxima along the hair shaft providing a good estimate for the day that GBCA injection occurred (R2 = 0.46; p = 0.0022); however, substantial within and between subject variation in the position of the GBCA peak was observed. Average area under the curve for gadolinium peaks in the hair samples was a better predictor of gadolinium dose (R2 = 0.41; p = 0.0046), compared to the average of peak maxima concentration. Correlation between area under the curve and dose suggests that LA-ICP-MS analysis of hair may be an effective method to evaluate gadolinium levels in subjects in vivo after exposure to GBCAs. This study demonstrates that analysis of human hair using techniques with high spatial resolution such as LA-ICP-MS has excellent potential to reveal time-dependent signatures of past exposures.

Effect of gadolinium perfusion magnetic resonance imaging on surgeons' management preferences in kienböck's disease. A survey study

In literature, the use of gadolinium perfusion magnetic resonance imaging (GP-MRI) is recommended in Kienböck's disease to evaluate the lunate bone's perfusion. This survey study sought to assess how GP-MRI findings affect the management preferences of hand surgeons. A questionnaire consisting of 11 scenarios differing in ulnar variance, GP-MRI findings and management preferences was developed. The scenarios were designed based on the last published clinical guidelines. The questionnaire was sent to the members of a national hand surgery society consisting of 160 hand surgeons. Sixty-six surgeons completed the questionnaire. The surgeons' preferences changed significantly by ulnar variance in stages II and IIIA, and by GP-MRI in stages I and II. No need for other diagnostic tools was found in any of the scenarios. Management preferences of the study participants related to alterations in ulnar variance and treatment choices in all stages were in accordance with previously published clinical and survey studies. This study showed that GP-MRI findings significantly changed the management preferences of hand surgeons in early stages of Kienböck's disease. There was no significant tendency among the participants to use further assessment tools beyond direct radiography, MRI, and GP-MRI. Given the study results and the literature, we emphasize the limited and well-defined indications of GP-MRI in Kienböck's disease.

Molecular MR Imaging of Prostate Cancer

This review summarizes recent developments regarding molecular imaging markers for magnetic resonance imaging (MRI) of prostate cancer (PCa). Currently, the clinical standard includes MR imaging using unspecific gadolinium-based contrast agents. Specific molecular probes for the diagnosis of PCa could improve the molecular characterization of the tumor in a non-invasive examination. Furthermore, molecular probes could enable targeted therapies to suppress tumor growth or reduce the tumor size.

Texture analysis on bi-parametric MRI for evaluation of aggressiveness in patients with prostate cancer

PURPOSE

To evaluate the association between texture parameters based on bi-parametric MRI and Gleason score (GS) in patients with prostate cancer (PCa) and to evaluate diagnostic performance of any significant parameter for discriminating clinically significant cancer (CSC, GS ≥ 7) from non-CSC.

METHODS

A total of 116 patients who had been confirmed as prostate adenocarcinoma by radical prostatectomy or biopsy were divided into a training (n = 65) and a validation dataset (n = 51). All of the patients underwent preoperative 3T-MRI. Texture analysis was performed on axial T2WI and ADC maps (generated from b values, 0 and 1000 s/mm²) using dedicated software to cover the whole tumor volume. The correlation coefficient was calculated to evaluate the association between texture parameters and GS, and subsequent multiple regression analyses were applied for the significant parameters. To extract an optimal cut-off value for prediction of CSC, ROC curve analysis was performed.

RESULTS

In the training dataset, gray-level co-occurrence matrix (GLCM) entropy on ADC map was the only significant indicator for GS (coefficient of determination R², 0.4227, P = 0.0034). The AUC of GLCM entropy on ADC map was 0.825 (95% CI 0.711-0.907) with a maximum accuracy of 82%, a sensitivity of 86%, a specificity of 71%. When a cut-off value of 2.92 was applied to the validation dataset, it showed an accuracy of 92%, a sensitivity of 98%, and a specificity of 70%.

CONCLUSION

GLCM entropy on ADC map was associated with GS in patients with PCa and its estimated accuracy for discriminating CSC from non-CSC was 82%.

Comparison of diagnostic accuracy between [18F]FDG PET/MRI and contrast-enhanced MRI in T staging for oral tongue cancer

OBJECTIVE

Integrated PET/MRI with [¹⁸F]FDG is advantageous in that it enables simultaneous PET and MR imaging with higher soft-tissue contrast, multiplanar image acquisition, and functional imaging capability without using fat suppression and gadolinium-based contrast agents (GBCAs). The aims of this study were to demonstrate the feasibility of [¹⁸F]FDG PET/MRI for assessing the extent of the primary tumor (T) in oral tongue cancer (OTC) based on the 8th edition of American Joint Committee on Cancer (AJCC) cancer staging system, and to compare the diagnostic accuracy between [¹⁸F]FDG PET/MRI and contrast-enhanced MRI (ceMRI).

METHODS

18 patients with biopsy-proven operable OTC underwent preoperative regional [¹⁸F]FDG PET/MRI and ceMRI within 2 weeks. For [¹⁸F]FDG PET/MRI, rainbow-colored PET images were overlaid on the corresponding MR images. Tumor size and the depth of invasion (DOI) were visually measured on [¹⁸F]FDG PET/MRI and ceMRI. The size, DOI, and clinical T stage were evaluated using the final surgical pathology as the reference.

RESULTS

Of the 18 OTCs, one was not detected by ceMRI due to metal artifacts from an artificial denture, and another due to superficial type (pathological DOI = 0 mm). Tumor sizes measured by ceMRI and [¹⁸F]FDG PET/MRI had significant positive correlations with the pathological size (r = 0.80 and r = 0.90, respectively), and DOIs measured by ceMRI and [¹⁸F]FDG PET/MRI had significant positive correlations with the pathological DOI (r = 0.74 and r = 0.64, respectively). The means ± SD of size (mm) were 20.4 ± 9.1, 22.9 ± 10.9, and 26.2 ± 10.0, and those of DOI (mm) were 7.1 ± 2.5, 6.9 ± 2.2, and 5.8 ± 3.2 for ceMRI, [¹⁸F]FDG PET/MRI, and pathology, respectively. A significant difference was observed in tumor size between ceMRI and pathology (p < 0.05), whereas no significant differences were observed between any other sizes, DOIs, or T stages. The accuracy for T status was 72% (13/18 including 2 undetectable cases) for ceMRI and 89% (16/18) for [¹⁸F]FDG PET/MRI.

CONCLUSIONS

Although shallow DOIs are often overestimated, regional [¹⁸F]FDG PET/MRI without fat suppression and gadolinium enhancement is comparable to and may be substituted for ceMRI in preoperative T staging for OTC patients, reducing metal artifacts and avoiding the adverse effects of GBCAs.

Comparison of pulmonary artery dimensions in swine obtained from catheter angiography, multi-slice computed tomography, 3D-rotational angiography and phase-contrast magnetic resonance angiography

Accurate pulmonary artery (PA) imaging is necessary for management of patients with complex congenital heart disease (CHD). The ability of newer imaging modalities such as 3D rotational angiography (3DRA) or phase-contrast magnetic resonance angiography (PC-MRA) to measure PA diameters has not been compared to established angiography techniques. Measurements of PA diameters (including PA stenosis and PA stents) from 3DRA and non-contrast-enhanced PC-MRA were compared to 2D catheter angiography (CA) and multi-slice computed tomography (MSCT) in a swine CHD model (n = 18). For all PA segments 3DRA had excellent agreement with CA and MSCT (ICC = 0.94[0.91-0.95] and 0.92[0.89-0.94]). 3DRA PA stenosis measures were similar to CA and MSCT and 3DRA was on average within 5% of 10.8 ± 1.3 mm PA stent diameters from CA and MSCT. For compliant PA segments, 3DRA was on average 3-12% less than CA (p < 0.05) and MSCT (p < 0.01) for 6-14 mm vessels. PC-MRA could not reliably visualize stents and distal PA vessels and only identified 34% of all assigned measurement sites. For measured PA segments, PC-MRA had good agreement to CA and MSCT (ICC = 0.87[0.77-0.92] and 0.83[0.72-0.90]) but PC-MRA overestimated stenosis diameters and underestimated compliant PA diameters. Excellent CA-MSCT PA diameter agreement (ICC = 0.95[0.93-0.96]) confirmed previous data in CHD patients. There was little bias in PA measurements between 3DRA, CA and MSCT in stenotic and stented PAs but 3DRA underestimates measurements of compliant PA regions. Accurate PC-MRA imaging was limited to unstented proximal PA anatomy.

Quantitative Measurement of Breast Density Using Personalized 3D-Printed Breast Model for Magnetic Resonance Imaging

Despite the development and implementation of several MRI techniques for breast density assessments, there is no consensus on the optimal protocol in this regard. This study aimed to determine the most appropriate MRI protocols for the quantitative assessment of breast density using a personalized 3D-printed breast model. The breast model was developed using silicone and peanut oils to simulate the MRI related-characteristics of fibroglandular and adipose breast tissues, and then scanned on a 3T MRI system using non-fat-suppressed and fat-suppressed sequences. Breast volume, fibroglandular tissue volume, and percentage of breast density from these imaging sequences were objectively assessed using Analyze 14.0 software. Finally, the repeated-measures analysis of variance (ANOVA) was performed to examine the differences between the quantitative measurements of breast volume, fibroglandular tissue volume, and percentage of breast density with respect to the corresponding sequences. The volume of fibroglandular tissue and the percentage of breast density were significantly higher in the fat-suppressed sequences than in the non-fat-suppressed sequences (p < 0.05); however, the difference in breast volume was not statistically significant (p = 0.529). Further, a fat-suppressed T2-weighted with turbo inversion recovery magnitude (TIRM) imaging sequence was superior to the non-fat- and fat-suppressed T1- and T2-weighted sequences for the quantitative measurement of breast density due to its ability to represent the exact breast tissue compositions. This study shows that the fat-suppressed sequences tended to be more useful than the non-fat-suppressed sequences for the quantitative measurements of the volume of fibroglandular tissue and the percentage of breast density.

Investigating the Impact of Gadolinium-Based Contrast Agents on the Corrected QT Interval

Introduction

The manufacturing labels for all currently marketed gadolinium-based MRI contrast agents describe adverse cardiac events reported during post-market use. The goal of this study was to determine prolongation of the rate-corrected QT interval occurs in the immediate setting after gadolinium-based MRI contrast agent injection.

Methods

This study enrolled adults scheduled to have a gadolinium-based MRI contrast agent injection as part of a diagnostic MRI. A single-lead electrocardiogram was recorded using the AliveCor Kardia® ECG (Mountain View, CA) device before and after injection. The rate-corrected QT interval was subsequently measured by two independent investigators. The QT interval was corrected for rate using the two most common formulas, originally cited by Bazett and Fridericia. These rate-corrected QT intervals from before and after gadolinium-based MRI contrast agent injection were compared using the Wilcoxon signed-rank test paired analysis.

Results

A total of 24 consenting adults had electrocardiogram that were free of motion artifact. The mean age of the final patient cohort was 59.4 years. There was an equal split of 12 men and 12 women. The mean pre-injection, rate-corrected QT interval, corrected using Bazett’s formula, was 395 msec. The mean post-injection, rate-corrected QT interval, corrected using Bazett’s formula, was 396 msec. The corrections using Fridericia's formula were 384 and 381 msec, respectively. There was no statistically significant change in Bazett-corrected QT interval (QTc-B) when pre-injection and post-injection values were directly compared.

Discussion

The results of the present investigation support the conclusion that gadolinium-based MRI contrast agents do not commonly affect rate-corrected QT interval in routine clinical use. While the frequency of rate-corrected QT interval prolongation might be overstated, the severity of adverse events is definitively not. A role for concomitant rate-corrected QT interval-prolonging drugs or unidentified rare factors such as genetic predisposition cannot be ruled out. The limitations of this study include its relatively small size and the implementation of a single-lead electrocardiogram to measure rate-corrected QT interval.

Conclusion

The present investigation revealed that significant rate-corrected QT interval prolongation, while previously reported in as many as 55% of patients after gadolinium-based MRI contrast agent injection, is not a common occurrence in the routine clinical setting.

The Value of Multiparametric Magnetic Resonance Imaging Sequences to Assist in the Decision Making of Muscle-invasive Bladder Cancer

Interim data from the PURE-01 study, using pembrolizumab before radical cystectomy in muscle-invasive bladder cancer (MIBC), suggested that multiparametric magnetic resonance imaging (mpMRI) was able to predict the pathologic response. Owing to the availability of novel effective therapies in MIBC, the possibility to assess tumor response easily has become exceedingly important. The primary objective of the present study was to evaluate the association between individual and combined MRI sequences, and the pathologic response in the final PURE-01 population. Images were internally evaluated and the diagnostic performance was analyzed for separate sequences, along with their combination. From February 2017 to December 2019, 143 patients were enrolled in PURE-01, and 123 with suitable paired imaging assessments before and after pembrolizumab tests (N = 246 mpMRI in total) were analyzed in relation to the pathologic response. The area under the curve (AUC) of the combination of all sequences to predict ypT0ypN0 response was 0.74. By excluding dynamic contrast enhancement (DCE) assessment, the AUC was 0.74. When looking at ypT_1/a/is ypN0 response, the AUC was 0.87 in both cases. Without DCE, 95% of patients with no evidence of disease resulted in ypT_1/a/is ypN0 and 65% ypT0ypN0 responders. In conclusion, the final results confirmed the reliability of mpMRI and suggested the opportunity to avoid intravenous gadolinium contrast to personalize bladder-sparing strategies in radiologically complete responders. PATIENT SUMMARY: We evaluated the reliability of multiparametric bladder magnetic resonance imaging to predict the pathologic response to pembrolizumab administered before radical cystectomy in muscle-invasive bladder cancer. We observed that this radiologic examination is promising in the attempt to identify opportunities to spare the bladder in selected, radiologically defined complete responders. We also observed that the use of intravenous gadolinium contrast can be avoided in future studies. ClinicalTrials.gov, number NCT02736266.

Contrast-enhanced magnetic resonance (MR) T1 mapping with low-dose gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) is promising in identifying clear cell renal cell carcinoma histopathological grade and differentiating fat-poor angiomyolipoma

Background

This study aimed to identify clear cell renal cell carcinoma (ccRCC) histopathological grade and differentiate it from fat-poor angiomyolipoma (AML). This was achieved through contrast-enhanced magnetic resonance (MR) T1 mapping with intravenous low-dose gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA).

Methods

In total, 56 consecutive patients received MR scanning between January 2016 and December 2018 using the pre- and post- contrast-enhanced T1 mapping sequences with low-dose Gd-DTPA (0.036 mmol/kg). RCCs were pathologically proven in 40 patients after surgery and graded according to the International Society of Urological Pathology (ISUP) classification system. Ten AMLs were pathologically proven by surgery histopathology and six AMLs were diagnosed by magnetic resonance imaging (MRI). Patients were followed up for more than half a year. The mean T1 values of the renal lesion and ipsilateral normal renal parenchyma were measured before and after Gd-DTPA administration (T1p and T1e). The reduction of T1 value (T1d) and the ratio of its reduction (T1d %) were calculated and compared.

Results

In 40 ccRCCs, higher-grade [International Society of Urologic Pathology (ISUP) grade 3 and 4] and lower-grade (ISUP grade 1 and 2) ccRCCs were noted in 13 and 27 patients, respectively. The mean T1p was 1,514.8±139.4 ms and the mean T1d was 907.7±193.7 ms in the higher-grade ccRCCs, which were significantly higher than in the lower-grade ccRCCs (T1p =1,251.7±151.5 ms and T1d =648.5±218.2 ms, respectively; P<0.001). Fat-poor AMLs had higher T1p (1,677.3±104.8 ms) and T1e (865.6±251.5 ms) as compared to ccRCCs (P<0.001). Combined T1p + T1d showed the highest area under the curve (AUC) (0.912) in the differentiation of higher-grade ccRCCs from lower-grade ccRCCs (P=0.010). Combined T1p + T1e had the highest AUC (0.956) in the differentiation between ccRCCs and fat-poor AMLs (P=0.010). All T1 mapping metrics could discriminate between normal renal parenchyma and renal lesions (P<0.001). No significant difference was found in the T1p and T1e at different parts of the ipsilateral normal renal parenchyma. Interobserver agreement for quantitative longitudinal relaxation time in the T1 maps was excellent.

Conclusions

Contrast-enhanced T1 mapping with low-dose Gd-DTPA may provide a more reliable and accurate approach in identifying ccRCCs histopathological grade and differentiating ccRCCs from fat-poor AMLs.

Investigation of potential adverse central nervous system effects after long term oral administration of gadolinium in mice

Objectives

To examine potential gadolinium (Gd) accumulation in the brain of healthy mice after long-term oral administration of Gd-containing food pellets and to investigate whether Gd leads to adverse central nervous system (CNS) effects, specifically focussing on locomotor impairment in Gd exposed compared to control animals.

Materials and methods

The local Animal Experimental Ethics Committee approved all procedures and applications. Fifteen female C57Bl/6 mice were orally exposed to a daily intake of 0.57 mmol Gd chloride/ kg body weight over a period of 90 weeks from the age of 4 weeks on. Gd-free, but otherwise equivalent experimental diets were given to the control group (N = 13). The animals were monitored daily by animal caretakers regarding any visible signs of distress and evaluated clinically every four weeks for the first 60 weeks and afterwards every two weeks for a better temporal resolution of potential long-term effects regarding impairment of motor performance and loss of body weight. The individual Gd content was measured using mass spectrometry in a sub-cohort of N = 6 mice.

Results

The absolute brain Gd levels of the Gd-exposed mice were significantly increased compared to control mice (0.033± 0.009 vs. 0.006± 0.002 nmol Gd/ g brain tissue). Long-term oral Gd exposure over almost the entire life-span did not lead to adverse CNS effects including locomotor changes (rotarod performance, p = 0.1467) in healthy mice throughout the study period. Gd-exposed mice showed less increased body weight compared to control mice during the study period (p = 0.0423). Histopathological alterations, such as hepatocellular vacuolization due to fatty change in the liver and a loss of nucleated cells in the red pulp of the spleen, were found in peripheral organs of both groups.

Conclusions

Low levels of intracerebral Gd caused by chronic oral exposure over almost the entire life span of mice did not lead to alterations in locomotor abilities in healthy mice throughout the normal aging process.

Vaginal discharge caused by lymphatic malformation identified by lymphoscintigraphy combined with T2-weighted magnetic resonance imaging

Prepubertal vaginal discharge is most commonly caused by vulvovaginitis and is rarely caused by lymphatic malformations, resulting in chylous vaginal discharge. The diagnosis of chylous vaginal discharge remains a challenge because of a knowledge gap. We describe a 12-year-old girl with intermittent vaginal discharge for 10 years. Although we found a high signal in the vagina on T2-weighted magnetic resonance imaging (MRI), the final diagnosis, vaginal lymphatic leakage, was established on lymphoscintigraphy. Lymphatic leakage in the vagina on lymphoscintigraphy was the key imaging feature of chylous vaginal discharge in this patient. Moreover, diffuse radioactivity was found in the abdomen and thorax on lymphoscintigraphy, which indicated the multiple cystic lymphatic malformations and intestinal lymphangiectasia combined with T2-weighted MRI. Thus, T2-weighted MRI could be used in combination with lymphoscintigraphy to simply identify chylous vaginal discharge.

Imaging Inflammation and Infection in the Gastrointestinal Tract

A variety of seemingly non-specific symptoms manifest within the gastrointestinal (GI) tract, particularly in the colon, in response to inflammation, infection, or a combination thereof. Differentiation between symptom sources can often be achieved using various radiologic studies. Although it is not possible to provide a comprehensive survey of imaging gastrointestinal GI tract infections in a single article, the purpose of this review is to survey several topics on imaging of GI tract inflammation and infections. The review discusses such modalities as computed tomography, positron emission tomography, ultrasound, endoscopy, and magnetic resonance imaging while looking at up-an-coming technologies that could improve diagnoses and patient comfort. The discussion is accomplished through examining a combination of organ-based and organism-based approaches, with accompanying selected case examples. Specific focus is placed on the bacterial infections caused by Shigella spp., Escherichia coli, Clostridium difficile, Salmonella, and inflammatory conditions of diverticulitis and irritable bowel disease. These infectious and inflammatory diseases and their detection via molecular imaging will be compared including the appropriate differential diagnostic considerations.

Evaluation of venous pathology of the lower extremities with triggered angiography non-contrast-enhanced magnetic resonance imaging

Background

To explore the diagnostic performance of triggered angiography non-contrast-enhanced magnetic resonance imaging (TRANCE-MRI) for the evaluation of venous pathology of the lower extremity.

Methods

This was a single-centre prospective cohort study of 25 patients with suspected venous disease in the lower extremities. Each patient received Doppler ultrasonography (for venous evaluation) before the scheduled TRANCE-MRI (for venous and arterial evaluations) on a 1.5 T MR scanner (Philips Ingenia, Philips Healthcare, Best, the Netherlands), followed by lymphography and computed tomography angiography that were arranged according to the diagnostic indications.

Results

The sensitivity, specificity and accuracy of TRANCE-MRI were 85.7%, 88/9 and 88%, respectively. The inter-rater agreement for deep vein thrombosis (DVT) of the thigh between the ultrasonography and TRANCE-MRI results was substantial agreement (Cohen’s kappa κ, 0.72). In ultrasonography-negative cases, TRANCE-MRI detected four additional cases (16%, 4/25) of DVT; three cases (12%, 3/25) of venous compression caused by pelvic lymphadenopathy, hip prosthesis or knee joint effusion; one case (4%, 1/25) of vena cava anomaly; two cases (8%, 2/25) of occult peripheral artery disease (PAD); and one case (4%, 1/25) of an occluded bypass graft.

Conclusion

TRANCE-MRI can be used as an alternative and objective tool for assessing lower extremity diseases, especially suspected venous pathology. Compared with ultrasonography, TRANCE-MRI plays a better role in assessing varicose veins of the lower extremities and deep veins of the pelvis and abdomen. However, false-positive results may occur in the left common iliac vein of elderly patients. Finally, occult PAD rarely occurs in patients with suspected lower extremity venous disease. Therefore, we recommend performing the TRANCE-MRV protocol instead of the full protocol (MRV + MRA) in the clinical setting in patients with venous scenarios.

Thoracic-paravertebral blocks: comparative anatomical study with different injection techniques and volumes

Background and objectives

We hypothesized that different injection techniques and volumes in thoracic-paravertebral blocks (TPVB) lead to different patterns of dye spread. In particular, we investigated whether an alternating injection technique leads to complete staining of all adjacent intercostal nerves.

Methods

This comparative anatomical investigation was performed using 10 or 20 mL of dye (Alcian Blue) in 10 unfixed donor cadavers (54 injections) that were designated for education or research purposes.

Results

In landmark-guided TPVB, the thoracic-paravertebral space (TPVS) was either not stained at all (spread of dye in the paraspinal muscles, n=3) or the dye was predominantly found in the epidural space (n=3). In ultrasound-guided TPVB, the TPVS was correctly identified in all cases (n=48). The sympathetic trunk was stained in 84.6% of injections (multi-injection technique: 100%), independent of injection technique and volume. The epidural space was stained more frequently (p≤0.001) if both the puncture site (sagittal transducer position) and guidance of the needle were more medial (77.8%). Finally, a higher injection volume (20 vs 10 mL) resulted in a higher number of stained intercostal nerves (p=0.04).

Conclusion

For ultrasound-guided techniques, a higher injection volume resulted in a larger number of stained intercostal nerves. Staining of the sympathetic trunk was independent of the injection technique. Epidural spread was observed significantly less frequently if the injection was lateral (transducer transversal) or with a strictly cranial injection direction (transducer sagittal). Landmark-guided injections reliably achieved the TPVS (and the epidural space) only after a needle advance of 2.5 cm after initial contact with the transverse process.

Differential absorbance study of interactions between europium, soil and aquatic NOM and model compounds

This study compared the binding of europium by soil and aquatic natural organic matter (NOM) exemplified by Pahokee Peat humic acid (PPHA) and Northern Reservoir NOM, respectively. NOM/Eu³⁺ interactions were measured based on the differential absorbance approach. The experimental results show that the binding of Eu³⁺ by humic acid isolated from agricultural soil results in several features of the differential spectra that are distinct from those observed for aquatic NOM. These features may be associated with the presence in soil NOM of functional groups similar to gallic acid. The binding of Eu³⁺ by NOM was modeled using a phenomenological approach that accounted for the involvement of dissimilar metal-binding functionalities. This study also introduced the concept of integrated differential absorbance; the use of that parameter allowed achieving a close fit between the experimental and model data. This study presents an alternative approach to ascertain mechanisms of, and differences in the interactions of europium with model compounds and natural organic matter with the provenance from soil and surface water.