Nephrogenic Systemic Fibrosis as a Complication after Gadolinium-Containing Contrast Agents: A Rapid Review

NSF evaluation of gadolinium biodistribution in renally impaired rats: Using novel metabolic Gd2O3 nanoparticles coated with β-cyclodextrin (Gd2O3@PCD) in MR molecular imaging

The use of conventional gadolinium(Gd)-based contrast agents in magnetic resonance imaging (MRI) poses a significant risk of Nephrogenic Systemic Fibrosis (NSF) syndrome in patients with impaired renal function (grades 4 and 5). To address this issue, a new study has introduced a novel metabolic Gadolinium oxide nanoparticle (Gd2O3 NPs) coated with β-cyclodextrin (βCD). The study aims to investigate NSF syndrome by quantifying tissue Gd deposition biodistribution in renal impairment rats using MR molecular imaging. This is the first study of its kind to use this approach. A group of 20 rats were divided into four groups, each containing five rats that underwent 5/6 nephrectomy. The rats received 12 intravenous injections of a novel homemade synthesized gadolinium oxide polycyclodextrin (Gd2O3@PCD) at a dose of 0.1 mmol/kg, conventional contrast agents (CAs) drugs of Omniscan (Gd-DTPA-BMA) and Dotarem (Gd-DOTA), at a dose of 2.5 mmol/kg, and 250 μl saline for two injections per week during six weeks. T1-weighted MR imaging was performed before the injections and once a week for six weeks to quantify Gd deposition in four different organs (skin, liver, heart, and lung) in rats using inductively coupled plasma mass spectrometry (ICP-MS). The relationship between Signal-to-Noise Ratio (SNR) and biodistribution of Gd deposition due to NSF-induced syndrome was also calculated. The results of the study showed that the Gd concentrations in tissues were significantly higher in the Gd2O3@PCD group compared to the other groups, without any significant histopathological changes (P < 0.05). In the Gd2O3@PCD group, Gd was mainly deposited in the skin, followed by the liver, lung, and heart, without any symptoms of thickening or hardening of the skin. The Gd concentrations in the skin, liver, lung, and heart were significantly lower in the Dotarem group than in the Omniscan group (P < 0.05). In the histopathological examinations, the Omniscan group showed increased cellularity in the dermis. A significant hyperintensity was observed in the Gd2O3@PCD-treated rats compared to the Dotarem and Omniscan groups in the liver, heart, and lung. Compared to conventional Gd-based CAs, the novel metabolically Gd2O3@PCD with increased SNR, biosafety, and a considerably lower probability of developing NSF, has potential applicability for diagnosing patients with renal diseases in clinical MR Molecular Imaging (MRMI).

Mn-Anti-CTLA4-CREKA-Sericin Nanotheragnostics for Enhanced Magnetic Resonance Imaging and Tumor Immunotherapy

The integration of magnetic resonance imaging (MRI), cGAS-STING, and anti-CTLA-4 (aCTLA-4) based immunotherapy offers new opportunities for tumor precision therapy. However, the precise delivery of aCTLA-4 and manganese (Mn), an activator of cGAS, to tumors remains a major challenge for enhanced MRI and active immunotherapy. Herein, a theragnostic nanosphere Mn-CREKA-aCTLA-4-SS (MCCS) is prepared by covalently assembling Mn2+, silk sericin (SS), pentapeptide CREKA, and aCTLA-4. MCCS are stable with an average size of 160 nm and is almost negatively charged or neutral at pH 5.5/7.4. T1-weighted images showed MCCS actively targeted tumors to improve the relaxation rate r1 and contrast time of MRI. This studies demonstrated MCCS raises reactive oxygen species levels, activates the cGAS-STING pathway, stimulates effectors CD8+ and CD80+ T cells, reduces regulatory T cell numbers, and increases IFN-γ and granzyme secretion, thereby inducing tumor cells autophagy and apoptosis in vitro and in vivo. Also, MCCS are biocompatible and biosafe. These studies show the great potential of Mn-/SS-based integrative material MCCS for precision and personalized tumor nanotheragnostics.

Ablative Treatments for Small Renal Masses and Management of Recurrences: A Comprehensive Review

This review focuses on ablative techniques for small renal masses (SRMs), including radiofrequency ablation (RFA), cryoablation (CA), microwave ablation (MWA), and irreversible electroporation (IRE), and discusses recurrence management. Through an extensive literature review, we outline the procedures, outcomes, and follow-up strategies associated with each ablative method. The review provides a detailed examination of these techniques-RFA, CA, MWA, and IRE-elucidating their respective outcomes. Recurrence rates vary among them, with RFA and CA showing comparable rates, MWA demonstrating favorable short-term results, and IRE exhibiting promise in experimental stages. For managing recurrences, various strategies are considered, including active surveillance, re-ablation, or salvage surgery. Surveillance is preferred post-RFA and post-CA, due to slow SRM growth, while re-ablation, particularly with RFA and CA, is deemed feasible without additional complications. Salvage surgery emerges as a viable option for larger or resistant tumors. While ablative techniques offer short-term results comparable to surgery, further research is essential to understand their long-term effects fully. Decisions concerning recurrence management should consider individual and tumor-specific factors. Imaging, notably contrast-enhanced ultrasounds, plays a pivotal role in assessing treatment success, emphasizing the necessity of a multidisciplinary approach for optimal outcomes. The lack of randomized trials highlights the need for further research.

Pharmacokinetics and Tolerability of the Cancer-Targeting MRI Contrast Agent MT218 in Healthy Males

OBJECTIVE

The aim of this study was to evaluate the pharmacokinetics and safety profile of MT218, a peptide-targeted gadolinium-based contrast agent, in healthy males.

MATERIALS AND METHODS

This was a double-blind, randomized, placebo-controlled, single-ascending-dose study including 30 healthy male subjects. In each dose group (0.01, 0.02, 0.04, and 0.08 mmol/kg), 4 subjects received MT218 and 2 subjects received placebo (saline) in bolus injections. The highest dose group (0.08 mmol/kg) was assessed in 2 cohorts, 1 fasted and 1 nonfasted. Clinical laboratory tests, vital signs, and electrocardiograms were investigated. Gadolinium concentrations were measured in plasma samples collected before administration and over a 24-hour period postinjection, and in urine specimens collected until 22 days. A noncompartmental model was used for pharmacokinetic analysis. A clinical and biological safety follow-up was carried out for up to 6 months.

RESULTS

No clinically significant modifications in biochemistry, hematology, urinalysis, electrocardiogram parameters, or vital signs were reported at any time point for any treatment group. No serious adverse events were observed in any dose group. Transient dizziness, hyperhidrosis, and injection site coldness were the main adverse events reported in both the MT218 and placebo groups. The mean total apparent clearance decreased slightly with increasing dose, and the median plasma t 1/2 ranged from 1.7 hours in the 0.01 mmol/kg group to 2.7 hours in the 0.08 mmol/kg nonfasted group. MT218 was rapidly excreted via renal filtration with 42.9% to 52.8% of the injected dose measured in urine within the first hour after administration, and 92.5% to 117.3% in urine within 24 hours. No Gd was detected by inductively coupled plasma mass spectrometry in urine after 21 days.

CONCLUSION

Single intravenous administration of MT218 was safely tolerated in the healthy males. Its pharmacokinetic parameters and safety profile are well aligned with those of other gadolinium-based contrast agents.

Gadolinium contrast agents- challenges and opportunities of a multidisciplinary approach: Literature review

Contrast agents is used in magnetic resonance imaging (MRI) to improve the visibility of the details of the organ structures. Gadolinium-based contrast agent (GBCA) has been used since 1988 in MRI for diagnostic and follow-up of patients, the gadolinium good properties make it an effective choice for enhance the signal in MRI by increase its intensity and shortening the relaxation time of the proton. Recently, many studies show a gadolinium deposition in different human organs due to release of free gadolinium various body organs or tissue, which led to increased concern about the use of gadolinium agents, in this study, the potential diseases that may affect the patient and side effects that appear on the patient and related to accumulation of gadolinium were clarified, the study focused on the organs such as brain and bones in which gadolinium deposition was found and the lesions associated with it, and the diseases associated with gadolinium retention includes Nephrogenic Systemic Fibrosis (NSF) and Gadolinium deposition disease (GDD). Some studies tended to improve the contrast agents by developing a new non-gadolinium agents or development of next-generation gadolinium agents. In this review article the latest knowledge about MRI contrast agent.

Comparison of Methemoglobin, Deoxyhemoglobin, and Ferrous Nitrosyl Hemoglobin as Potential MRI Contrast Agents

Gadolinium-based contrast agents (GBCAs) are in widespread use to enhance magnetic resonance imaging for evaluating vascular pathology. However, safety concerns and limitations regarding the use of GBCAs has led to an increased interest in alternative contrast agents. Previously, methemoglobin (metHb) and oxygen-free hemoglobin (HHb) have been shown to increase the T1-weighted signal intensity of blood, which is associated with a decrease in the T1 parameter and an enhanced contrast of the image. Thus, a lower T1 value compared to the baseline value is favorable for imaging. However, it is unknown as to whether metHb or HHb would be a stronger and more appropriate contrast agent and to what extent the T1-weighted signal is affected by concentration. This study evaluated T1-weighted images of blood samples over a range of metHb and HHb concentrations, as well as ferrous nitrosyl hemoglobin (HbIINO) concentrations. Comparison of T1 values from a baseline value of ~ 1500 ms showed that metHb is the strongest contrast agent (T1 ~ 950 ms at 20% metHb) and that HHb is a relatively weak contrast agent (T1 ~ 1450 ms at 20% HHb). This study showed for the first time that HbIINO can provide a contrast effect, although not as strong as metHb but stronger than HHb (T1 estimated as 1250 ms at 20% HbIINO). With metHb providing a viable contrast between 10 and 20%, metHb has the potential to be a safe and effective contrast agent since it can be naturally converted back to hemoglobin.

Mn(II) complex impregnated porous silica nanoparticles as Zn(II)-responsive "Smart" MRI contrast agent for pancreas imaging

Type-1 and type-2 diabetes mellitus are metabolic disorders governed by the functional efficiency of pancreatic β-cells. The activities of the cells toward insulin production, storage, and secretion are accompanied by Zn(II) ions. Thus, for non-invasive pathology of the cell, developing Zn(II) ion-responsive MRI-contrast agents has earned considerable interest. In this report, we have synthesized a seven-coordinate, mono(aquated) Mn(II) complex (1), which is impregnated within a porous silica nanosphere of size 13.2 nm to engender the Mn(II)-based MRI contrast agent, complex 1@SiO2NP. The surface functionalization of the nanosphere by the Py2Pic organic moiety for the selective binding of Zn(II)-ions yields complex 1@SiO2-Py2PicNP, which exhibits r1 = 13.19 mM-1 s-1. The relaxivity value elevates to 20.38 mM-1 s-1 in the presence of 0.6 mM BSA protein at pH 7.4. Gratifyingly, r1 increases linearly with the increase of Zn(II) ion concentration and reaches 39.01 mM-1 s-1 in the presence of a 40 fold excess of the ions. Thus, Zn(II)-responsive contrast enhancement in vivo is envisaged by employing the nanoparticle. Indeed, a contrast enhancement in the pancreas is observed when complex 1@SiO2-Py2PicNP and a glucose stimulus are administered in fasted healthy C57BL/6 mice at 7 T.

Safety, accuracy, and prediction of prognosis in patients with end-stage chronic kidney disease undergoing dobutamine stress cardiac magnetic resonance imaging

Introduction

Advanced chronic kidney disease (CKD) is an independent risk factor for coronary artery disease (CAD). Due to its unique uremia-derived pathophysiology of atherosclerosis and the limitations of using potentially harmful contrast agents, the best non-invasive approach to assess CAD in these patients remains unclear. We sought to investigate the accuracy, safety, and prognosis of patients with severe CKD undergoing dobutamine stress cardiac magnetic resonance imaging (CMR).

Materials and methods

In this retrospective, single-center study, patients on dialysis or with a glomerular filtration rate of <15 ml/min/1.73 m2 who underwent dobutamine stress CMR were included. A rest and stress wall motion analysis was performed using dobutamine/atropine as stressor. The target heart rate was 85% of the maximum heart rate. Periprocedural adverse events and 1-year follow-up data were obtained.

Results

A total of 176 patients (127 men, 49 women) with a mean age of 60.9 ± 14.7 years were included, of which 156 patients were on permanent dialysis. Short-term symptoms such as angina or shortness of breath during stress CMR were frequent (22.1%), but major complications were rare (one patient with myocardial infarction, 0.6%). The 1-year event rate was high (16.4%) with a significant independent correlation to reduced ejection fraction at rest (p = 0.037) and failure to achieve the target heart rate (p = 0.029). The overall accuracy for predicting significant CAD was good (sensitivity of 71.4%, specificity of 98.4%) and excellent if the target heart rate was achieved (83.3%, 97.9%). A negative stress CMR was highly predictive for the absence of major adverse cardiac event or any coronary revascularization during the 1-year follow-up (negative predictive value of 95.0%).

Discussion

Dobutamine stress CMR is a safe and accurate diagnostic imaging technique in patients at advanced stages of chronic kidney disease. A reduced ejection fraction and the inability to reach the target heart rate are independent predictors of a poor outcome.

Care of the Patient With Abnormal Kidney Test Results

Blood and urine tests are commonly performed by clinicians in both ambulatory and hospital settings that detect chronic and acute kidney disease. Thresholds for these tests have been established that signal the presence and severity of kidney injury or dysfunction. In the appropriate clinical context of a patient's history and physical examination, an abnormal test result should trigger specific actions for clinicians, including reviewing patient medication use, follow-up testing, prescribing lifestyle modifications, and specialist referral. Tests for kidney disease can also be used to determine the future risk for kidney failure as well as cardiovascular death.

Multiparametric MRI of Solid Renal Masses: Principles and Applications of Advanced Quantitative and Functional Methods for Tumor Diagnosis and Characterization

Solid renal masses (SRMs) are increasingly detected and encompass both benign and malignant masses, with renal cell carcinoma (RCC) being the most common malignant SRM. Most patients with SRMs will undergo management without a priori pathologic confirmation. There is an unmet need to noninvasively diagnose and characterize RCCs, as significant variability in clinical behavior is observed and a wide range of differing management options exist. Cross-sectional imaging modalities, including magnetic resonance imaging (MRI), are increasingly used for SRM characterization. Multiparametric (mp) MRI techniques can provide insight into tumor biology by probing different physiologic/pathophysiologic processes noninvasively. These include sequences that probe tissue microstructure, including intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) and T₁ relaxometry; oxygen metabolism (blood oxygen level dependent [BOLD-MRI]); as well as vascular flow and perfusion (dynamic contrast-enhanced MRI [DCE-MRI] and arterial spin labeling [ASL]). In this review, we will discuss each mpMRI method in terms of its principles, roles, and discuss the results of human studies for SRM assessment. Future validation of these methods may help to enable a personalized management approach for patients with SRM in the emerging era of precision medicine. EVIDENCE LEVEL: 5. TECHNICAL EFFICACY: 2.

Multiple directional DWI combined with T2WI in predicting muscle layer and Ki-67 correlation in bladder cancer in 3.0-T MRI

OBJECTIVE

To investigate the value of 3.0T MRI multi-directional diffusion-weighted imaging (DWI) combined with T2WI morphological features and lesion distribution in preoperative prediction of muscle layer invasion of bladder cancer (BC) and the correlation with postoperative Ki-67.

MATERIALS AND METHODS

This retrospective study enrolled patients with BC between 2019 and 2021. Patients with muscular invasive bladder cancer (MIBC) or non-muscular invasive BC (NMIBC) were also analyzed by preoperative 3.0T MRI aFostic efficacy.

RESULTS

A total of 186 patients were enrolled. About 27 patients with MIBC (35 lesions in total) and 62 with NMIBC (99 lesions in total). We found the tumor with a larger size, a wide base, and a smaller apparent dispersion coefficient (ADC) value and normalized ADC(nADC) value, without a stalk, presenting a greater risk of muscle invasion. ADC value, nADC value, maximum diameter, and stalk were independently associated with muscle invasion. Lesions located at the bladder fundus or involvement of multiple sites were independently associated with muscle invasion compared to the bladder body. In combination with morphological features, the AUCs of ADC and nADC showed accuracies of 0.925 and 0.947-0.951, respectively. TADC and nTADC showed the best diagnostic efficacy in multiple respects. KI-67 LI was negatively correlated with ADC and nADC values.

CONCLUSIONS

This is the first report in which we found Multi-directional DWI combined with T2WI in 3.0T MRI can be used to predict the muscle layer invasion of bladder cancer. ADC values reflect the muscular invasion of bladder cancer and show a moderate negative correlation with Ki-67. It is especially suitable for bladder cancer patients with renal insufficiency or tumor recurrence.

Coronary Computed Tomography vs. Cardiac Magnetic Resonance Imaging in the Evaluation of Coronary Artery Disease

Coronary artery disease (CAD) represents a widespread burden to both individual and public health, steadily rising across the globe. The current guidelines recommend non-invasive anatomical or functional testing prior to invasive procedures. Both coronary computed tomography angiography (cCTA) and stress cardiac magnetic resonance imaging (CMR) are appropriate imaging modalities, which are increasingly used in these patients. Both exhibit excellent safety profiles and high diagnostic accuracy. In the last decade, cCTA image quality has improved, radiation exposure has decreased and functional information such as CT-derived fractional flow reserve or perfusion can complement anatomic evaluation. CMR has become more robust and faster, and advances have been made in functional assessment and tissue characterization allowing for earlier and better risk stratification. This review compares both imaging modalities regarding their strengths and weaknesses in the assessment of CAD and aims to give physicians rationales to select the most appropriate modality for individual patients.

Ferumoxytol-Enhanced Cardiac Magnetic Resonance Angiography and 4D Flow: Safety and Utility in Pediatric and Adult Congenital Heart Disease

Cardiac magnetic resonance imaging and angiography have a crucial role in the diagnostic evaluation and follow up of pediatric and adult patients with congenital heart disease. Although much of the information required of advanced imaging studies can be provided by standard gadolinium-enhanced magnetic resonance imaging, the limitations of precise bolus timing, long scan duration, complex imaging protocols, and the need to image small structures limit more widespread use of this modality. Recent experience with off-label diagnostic use of ferumoxytol has helped to mitigate some of these barriers. Approved by the U.S. FDA for intravenous treatment of anemia, ferumoxytol is an ultrasmall superparamagnetic iron oxide nanoparticle that has a long blood pool residence time and high relaxivity. Once metabolized by macrophages, the iron core is incorporated into the reticuloendothelial system. In this work, we aim to summarize the evolution of ferumoxytol-enhanced cardiovascular magnetic resonance imaging and angiography and highlight its many applications for congenital heart disease.

Ferumoxtran-10-enhanced 3-T Magnetic Resonance Angiography of Pelvic Arteries: Initial Experience

BACKGROUND

Patients with renal impairment cannot undergo angiography because iodine and gadolinium contrast agents are contraindicated. Iron-containing ultrasmall superparamagnetic iron oxide particles, such as ferumoxtran-10, are not contraindicated in these patients. Thus, patients with renal failure can still undergo angiography with ferumoxtran-10.

OBJECTIVE

To evaluate the visibility of pelvic vessels with magnetic resonance angiography (MRA) using ferumoxtran-10 as contrast agent.

DESIGN, SETTING, AND PARTICIPANTS

Three hundred and eighty-one patients diagnosed with primary or recurrent prostate cancer underwent pelvic ferumoxtran-10 MRA. Eleven anatomical pelvic-vessel segments per patient were evaluated using qualitative and quantitative criteria for image quality (IQ), vessel visibility (VV), and the contrast-to-noise ratio (CNR).

INTERVENTION

Ferumoxtran-10-enhaced MRA.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

IQ, VV, and CNR were assessed on a 5-point scale for each data set/vessel segment (very poor, poor, moderate, good, and excellent).

RESULTS AND LIMITATIONS

IQ was good to excellent for 98.2% of the data sets and VV was good to excellent for 97.7% of all vessel segments. The mean CNR for all segments was 88.13 (standard deviation 4.22). Contrast bolus imaging cannot be performed with this technique, so it is impossible to visualize the arterial or venous phase separately. The timing of contrast administration is also a limitation, with MRA performed 1 d after contrast infusion.

CONCLUSIONS

Ferumoxtran-10 MRA showed excellent image quality and visibility for pelvic vessels. In addition, the homogeneity of the intraluminal contrast was superior. Patients with preterminal or terminal renal function can benefit from ferumoxtran-10 MRA if visualization of their pelvic vessels is required.

PATIENT SUMMARY

Magnetic resonance imaging of blood vessels using a contrast agent called ferumoxtran-10 is a promising technique for patients with impaired kidney function, as it provides high-quality visualization of blood vessels in the pelvis.

Targeted Contrast Agents for Magnetic Resonance Molecular Imaging of Cancer

Magnetic resonance imaging (MRI) is a clinical imaging modality that provides high-resolution images of soft tissues, including cancerous lesions. Stable gadolinium(III) chelates have been used as contrast agents (CA) in MRI to enhance the contrast between the tissues of interest and surrounding tissues for accurate diagnostic imaging. Magnetic resonance molecular imaging (MRMI) of cancer requires targeted CA to specifically elucidate cancer-associated molecular processes and can provide high-resolution delineation and characterization of cancer for precision medicine. The main challenge for MRMI is the lack of sufficient sensitivity to detect the low concentration of the cellular oncogenic markers. In addition, targeted CA must satisfy regulatory safety requirements prior to clinical development. Up to now, there is no FDA-approved targeted CA for MRMI of cancer.In this Account, we discuss the latest developments in the design and development of clinically translatable targeted CA for MRMI of cancer, with an emphasis on our own research. The primary limitation of MRMI can be overcome by designing small molecular targeted CA to target abundant cancer-specific targets found in the tumor microenvironment (TME). For example, aggressive tumors have a unique extracellular matrix (ECM) composed of oncoproteins, which can be used as targetable markers for MRMI. We have designed and prepared small peptide conjugates of clinical contrast agents, including Gd-DTPA and Gd-DOTA, to target fibrin-fibronectin clots in tumors. These small molecular CA have been effective in enhancing MRMI detection of solid tumors and have demonstrated the ability to detect submillimeter cancer micrometastases in mouse tumor models, exceeding the detection limit of current clinical imaging modalities. We have also identified extradomain B fibronectin (EDB-FN), an oncofetal subtype of fibronectin, as a promising TME target to leverage in the design and development of small peptide targeted CA for clinical translation. The expression level of EDB-FN is correlated with invasiveness of cancer cells and poor patient survival of multiple cancer types. ZD2 peptide with a sequence of seven amino acids (TVRTSAD) was identified to specifically bind to the EDB protein fragment. Several ZD2 conjugates of macrocyclic GBCA, including Gd-DOTA and Gd(HP-DO3A), have been synthesized and tested in mouse tumor models. ZD2-N3-Gd(HP-DO3A) (MT218) with a high r₁ relaxivity was selected as the lead agent for clinical translation. The physicochemical properties and preclinical assessments of MT218 are summarized in this Account. MRMI of EDB-FN with MT218 can effectively detect invasive tumors of multiple cancers with risk-stratification and monitor tumor response to anticancer therapies in mouse models. Currently, MT218 is in clinical trials for precision cancer MRMI. Herein, we will show that using targeted MRI contrast agents specific to abundant TME biomarkers is a pragmatic solution for effective precision cancer imaging in high spatial resolution. And thus, we illustrate a replicable approach for CA development that is vital for cancer MRMI.

Successful Adrenal Vein Sampling Using Dexamethasone Premedication in Patients With Iodine Contrast Media Allergy

Context

Preparation of patients with iodine contrast media (ICM) allergy who require adrenal vein sampling (AVS) to establish source of aldosterone excess of their confirmed primary aldosteronism (PA) is controversial. Usual premedication with high-dose prednisone can interfere with cortisol determinations, possibly altering the aldosterone to cortisol ratios for the identification of lateralized aldosterone excess.

Objective

We aimed to evaluate the efficacy and safety of premedication with high-dose dexamethasone to perform AVS in patients with ICM.

Methods

One hundred and seventy-seven consecutive patients with confirmed PA who underwent bilateral simultaneous basal and post-ACTH bolus AVS at our center between January 2010 and December 2020 were retrospectively analyzed for history of ICM allergy. A total of 7 patients (4%) with previous allergic reactions to ICM were prepared with 3 doses of 7.5 mg dexamethasone premedication rather than the usual 50 mg of prednisone.

Results

No breakthrough allergic reactions were reported in the 7 patients. Despite adequate serum cortisol suppression following dexamethasone, the basal and post-ACTH selectivity index were respectively &gt; 2 and &gt; 5 bilaterally in all patients, confirming adequate cannulation of both adrenal veins. Four patients had lateralized ratios (A/C ratio &gt; 2 basally and &gt; 4 post-ACTH), while 3 had bilateral source during AVS study. In the 3 patients undergoing unilateral adrenalectomy for lateralized source and contralateral suppression and adequate follow-up data, cure of PA was achieved at mean 58 months postoperatively.

Conclusion

AVS using dexamethasone premedication is safe and accurate for diagnosing the source of aldosterone excess in patients with PA and ICM allergy.

Multiparametric Functional MRI of the Kidney: Current State and Future Trends with Deep Learning Approaches

BACKGROUND

 Until today, assessment of renal function has remained a challenge for modern medicine. In many cases, kidney diseases accompanied by a decrease in renal function remain undetected and unsolved, since neither laboratory tests nor imaging diagnostics provide adequate information on kidney status. In recent years, developments in the field of functional magnetic resonance imaging with application to abdominal organs have opened new possibilities combining anatomic imaging with multiparametric functional information. The multiparametric approach enables the measurement of perfusion, diffusion, oxygenation, and tissue characterization in one examination, thus providing more comprehensive insight into pathophysiological processes of diseases as well as effects of therapeutic interventions. However, application of multiparametric fMRI in the kidneys is still restricted mainly to research areas and transfer to the clinical routine is still outstanding. One of the major challenges is the lack of a standardized protocol for acquisition and postprocessing including efficient strategies for data analysis. This article provides an overview of the most common fMRI techniques with application to the kidney together with new approaches regarding data analysis with deep learning.

METHODS

 This article implies a selective literature review using the literature database PubMed in May 2021 supplemented by our own experiences in this field.

RESULTS AND CONCLUSION

 Functional multiparametric MRI is a promising technique for assessing renal function in a more comprehensive approach by combining multiple parameters such as perfusion, diffusion, and BOLD imaging. New approaches with the application of deep learning techniques could substantially contribute to overcoming the challenge of handling the quantity of data and developing more efficient data postprocessing and analysis protocols. Thus, it can be hoped that multiparametric fMRI protocols can be sufficiently optimized to be used for routine renal examination and to assist clinicians in the diagnostics, monitoring, and treatment of kidney diseases in the future.

KEY POINTS

  · Multiparametric fMRI is a technique performed without the use of radiation, contrast media, and invasive methods.. · Multiparametric fMRI provides more comprehensive insight into pathophysiological processes of kidney diseases by combining functional and structural parameters.. · For broader acceptance of fMRI biomarkers, there is a need for standardization of acquisition, postprocessing, and analysis protocols as well as more prospective studies.. · Deep learning techniques could significantly contribute to an optimization of data acquisition and the postprocessing and interpretation of larger quantities of data..

CITATION FORMAT

· Zhang C, Schwartz M, Küstner T et al. Multiparametric Functional MRI of the Kidney: Current State and Future Trends with Deep Learning Approaches. Fortschr Röntgenstr 2022; DOI: 10.1055/a-1775-8633.

Is a Patient with Paget's Disease of Bone Suitable for Living Kidney Donation?-Decision-Making in Lack of Clinical Evidence

Living donor kidney transplantation is a widely performed medical procedure. Living kidney donation requires an in-depth health assessment of candidates. The potential living kidney donor must remain healthy after kidney removal. A consequence of donation can be a decrease in glomerular filtration rate (GFR), and donors can become at risk of developing chronic kidney disease (CKD). We present a rationale for potential living kidney donor withdrawal due to Paget's disease of bone (PDB) based on a literature review. The treatment for PDB includes the use of, for example, non-steroidal anti-inflammatory drugs (NSAIDs), which can lead to acute kidney injury (AKI) as well as CKD, or bisphosphonates, which are not recommended for patients with decreased GFR.

Design of High-Relaxivity Polyelectrolyte Nanocapsules Based on Citrate Complexes of Gadolinium(III) of Unusual Composition

Through nuclear magnetic relaxation and pH-metry, the details of the complexation of gadolinium(III) ions with citric acid (H₄L) in water and aqueous solutions of cationic polyelectrolytes are established. It is shown that the presence of poly(ethylene imine) (PEI) in solution affects magnetic relaxation behavior of gadolinium(III) complexes with citric acid (Cit) to a greater extent than polydiallyldimethylammonium chloride (PDDC). A large increase in relaxivity (up to 50 mM⁻¹s⁻¹) in the broad pH range (4–8) is revealed for the gadolinium(III)–citric acid–PEI system, which is particularly strong in the case of PEI with the molecular weight of 25 and 60 kDa. In weakly acidic medium (pH 3–7), the presence of PEI results in the formation of two tris-ligand associates [Gd(H₂L)₃]³⁻ and [Gd(H₂L)₂(HL)]⁴⁻, which do not exist in aqueous medium. In weakly alkaline medium (pH 7–10), formation of ternary complexes Gd(III)–Cit–PEI with the Gd(III)–to–Cit ratio of 1:2 is evidenced. Using transmission electron microscopy (TEM) and dynamic light scattering techniques (DLS), the formation of the particles with the size of 50–100 nm possessing narrow molecular-mass distribution (PDI 0.08) is determined in the solution containing associate of PEI with tris-ligand complex [Gd(H₂L)₂(HL)]⁴⁻.

In Vitro Toxicological Assessment of Gadodiamide in Normal Brain SVG P12 Cells

BACKGROUND/AIM

Magnetic resonance imaging (MRI) is a technique for evaluating patients with primary and metastatic tumors. The contrast agents improve the diagnostic accuracy of MRI. Large quantities of a contrast agent must be administrated into the patient to obtain useful images, which leads to cell injury. Gadolinium has been reported to cause central lobular necrosis of the liver and nephrogenic systemic fibrosis. However, the toxicity caused on brain tissue is uncertain.

MATERIALS AND METHODS

This study mainly aimed on the in vitro study of high concentration (2 and 5-fold of normal concentration) gadolinium-based contrast agents (GBCAs), gadodiamide (Omniscan^®), on normal brain glial SVG P12 cells. MTT assay, DAPI staining, immunofluorescent staining, LysoTracker Red staining, and western blotting analysis were applied on the cells.

RESULTS

The viability of gadodiamide (1.3, 2.6, 5.2, 13 and 26 mM)-treated SVG P12 cells was significantly reduced after 24 h of incubation. Gadodiamide caused significant autophagic flux at 2.6, 5.2 and 13.0 mM as seen by acridine orange (AO) staining, LC-3-GFP and LysoTracker Red staining. The expression levels of autophagy-related proteins such as beclin-1, ATG-5, ATG-14 and LC-3 II were up-regulated after 24 h of gadodiamide incubation. Autophagy inhibitors including 3-methyladenine (3-MA), chloroquine (CQ) and bafilomycin A1 (Baf) significantly alleviated the autophagic cell death effect of gadodiamide on normal brain glial SVG P12 cells. Gadodiamide induced significant apoptotic effects at 5.2 mM and 13.0 mM as seen by DAPI staining and the pan-caspase inhibitor significantly alleviated the apoptotic effect. Gadodiamide at 5.2 mM and 13.0 mM inhibited antiapoptotic protein expression levels of Bcl-2 and Bcl-XL, while promoted pro-apoptotic protein expression levels of Bax, BAD, cytochrome c, Apaf-1, cleaved-caspase-9 and cleaved-caspase-3.

CONCLUSION

Normal brain glial SVG P12 cells treated with high concentrations of gadodiamide can undergo autophagy and apoptosis.