Viscosity of contrast media perturbs renal hemodynamics

High-mobility group box 1 and its related receptors: potential therapeutic targets for contrast-induced acute kidney injury

Percutaneous coronary intervention (PCI) is a crucial diagnostic and therapeutic approach for coronary heart disease. Contrast agents' exposure during PCI is associated with a risk of contrast-induced acute kidney injury (CI-AKI). CI-AKI is characterized by a sudden decline in renal function occurring as a result of exposure to intravascular contrast agents, which is associated with an increased risk of poor prognosis. The pathophysiological mechanisms underlying CI-AKI involve renal medullary hypoxia, direct cytotoxic effects, endoplasmic reticulum stress, inflammation, oxidative stress, and apoptosis. To date, there is no effective therapy for CI-AKI. High-mobility group box 1 (HMGB1), as a damage-associated molecular pattern molecule, is released extracellularly by damaged cells or activated immune cells and binds to related receptors, including toll-like receptors and receptor for advanced glycation end product. In renal injury, HMGB1 is expressed in renal tubular epithelial cells, macrophages, endothelial cells, and glomerular cells, involved in the pathogenesis of various kidney diseases by activating its receptors. Therefore, this review provides a theoretical basis for HMGB1 as a therapeutic intervention target for CI-AKI.

Assessing the efficacy of saline flush in frequency-domain optical coherence tomography for intracoronary imaging

BACKGROUND

The increased amount of contrast media in frequency-domain optical coherence tomography (FD-OCT) imaging during percutaneous coronary intervention (PCI) has raised potential concerns regarding impairment of renal function.

OBJECTIVES

This study aimed to evaluate the effectiveness of heparinized saline flush in FD-OCT-guided PCI and identify clinical factors contributing to optimal image quality.

METHODS

We retrospectively collected 100 lesions from 90 consecutive patients, and a total of 200 pullbacks were analyzed for the initial and final evaluation in which saline was used as the flushing medium.

RESULTS

The study population had a mean age of 73, with 52% having chronic kidney disease (CKD). The median amount of contrast used was 28 ml, and no complications were observed associated with saline flush OCT. Imaging quality was then categorized as excellent, good, or unacceptable. Among the total runs, 87% demonstrated clinically acceptable image quality, with 66.5% classified as excellent images and 20.5% classified as good images. Independent predictors of excellent images included lumen area stenosis ≥ 70% (adjusted odds ratio [OR] 2.37, 95% confidence interval [CI] 1.02-5.47, P = 0.044), and the use of intensive flushing (adjusted OR 2.06, 95% CI 1.11-3.86, P = 0.023) defined as a deep engagement of guiding catheter (GC) or a selective insertion of guide extension catheter (GE). Intensive flushing was performed in 60% of the total pullbacks, and it was particularly effective in improving image quality in the left coronary artery (LCA).

CONCLUSION

The use of saline flush during FD-OCT imaging was safe and feasible, which had a benefit in renal protection with adequate imaging quality.

Monitoring kidney size to interpret MRI-based assessment of renal oxygenation in acute pathophysiological scenarios

AIM

Tissue hypoxia is an early key feature of acute kidney injury. Assessment of renal oxygenation using magnetic resonance imaging (MRI) markers T₂ and T₂ * enables insights into renal pathophysiology. This assessment can be confounded by changes in the blood and tubular volume fractions, occurring upon pathological insults. These changes are mirrored by changes in kidney size (KS). Here, we used dynamic MRI to monitor KS for physiological interpretation of T₂ * and T₂ changes in acute pathophysiological scenarios.

METHODS

KS was determined from T₂ *, T₂ mapping in rats. Six interventions that acutely alter renal tissue oxygenation were performed directly within the scanner, including interventions that change the blood and/or tubular volume. A biophysical model was used to estimate changes in O₂ saturation of hemoglobin from changes in T₂ * and KS.

RESULTS

Upon aortic occlusion KS decreased; this correlated with a decrease in T₂ *, T₂ . Upon renal vein occlusion KS increased; this negatively correlated with a decrease in T₂ *, T₂ . Upon simultaneous occlusion of both vessels KS remained unchanged; there was no correlation with decreased T₂ *, T₂ . Hypoxemia induced mild reductions in KS and T₂ *, T₂ . Administration of an X-ray contrast medium induced sustained KS increase, with an initial increase in T₂ *, T₂ followed by a decrease. Furosemide caused T₂ *, T₂ elevation and a minor increase in KS. Model calculations yielded physiologically plausible calibration ratios for T₂ *.

CONCLUSION

Monitoring KS allows physiological interpretation of acute renal oxygenation changes obtained by T₂ *, T₂ . KS monitoring should accompany MRI-oximetry, for new insights into renal pathophysiology and swift translation into human studies.

Renal resistance index independently predicts worsening of renal function after coronary angiography

The renal resistance index (RRI) has been demonstrated to be a useful parameter that can detect patients at a high risk of worsening of renal function (WRF). This study was designed to evaluate the role of the RRI in predicting WRF mediated by the intravascular administration of contrast media. We enrolled patients who were referred for coronary angiography. Renal arterial echo-color Doppler was performed to calculate the RRI. WRF was defined as an increase of > 0.3 mg/dL and at least 25% of the baseline value in creatinine concentration 24-48 h after coronary angiography. Among the 148 patients enrolled in this study, 18 (12%) had WRF. In the multivariate logistic analysis, the RRI was independently associated with WRF (odds ratio [OR]: 1.22; 95% confidence interval [CI]: 1.09-1.36; p = 0.001). After angiography, the RRI significantly increased in both patients with and without WRF. In the receiver operating characteristic curve analyses for WRF, the RRI at baseline and after angiography showed similar accuracy, and the best cutoff value for predicting WRF was 70%. In patients undergoing coronary angiography, the RRI is independently associated with WRF, probably because it provides more accurate information about cardiorenal pathophysiological factors and reflects kidney hemodynamic status and flow reserve.

Contrast-induced acute kidney injury and its contemporary prevention

The complexity and application range of interventional and diagnostic procedures using contrast media (CM) have recently increased. This allows more patients to undergo procedures that involve CM administration. However, the intrinsic CM toxicity leads to the risk of contrast-induced acute kidney injury (CI-AKI). At present, effective therapy of CI-AKI is rather limited. Effective prevention of CI-AKI therefore becomes crucially important. This review presents an in-depth discussion of CI-AKI incidence, pathogenesis, risk prediction, current preventive strategies, and novel treatment possibilities. The review also discusses the difference between CI-AKI incidence following intraarterial and intravenous CM administration. Factors contributing to the development of CI-AKI are considered in conjunction with the mechanism of acute kidney damage. The need for ultimate risk estimation and the prediction of CI-AKI is stressed. Possibilities of CI-AKI prevention is evaluated within the spectrum of existing preventive measures aimed at reducing kidney injury. In particular, the review discusses intravenous hydration regimes and pre-treatment with statins and N-acetylcysteine. The review further focuses on emerging alternative imaging technologies, alternative intravascular diagnostic and interventional procedures, and new methods for intravenous hydration guidance; it discusses the applicability of those techniques in complex procedures and their feasibility in current practise. We put emphasis on contemporary interventional cardiology imaging methods, with a brief discussion of CI-AKI in non-vascular and non-cardiologic imaging and interventional studies.

Fluid administration strategies for the prevention of contrast-associated acute kidney injury

PURPOSE OF REVIEW

The known timing of contrast media exposure in patients identified as high-risk for contrast-associated acute kidney injury (CA-AKI) enables the use of strategies to prevent this complication of intravascular contrast media exposure. Although multiple preventive strategies have been proposed, periprocedural fluid administration remains as the primary preventive strategy. This is a critical review of the current evidence evaluating a variety of fluid administration strategies in CA-AKI.

RECENT FINDINGS

Fluid administration strategies to prevent CA-AKI include comparisons of intravenous (i.v.) to no fluid administration, different fluid solutions, duration of fluid administration, oral hydration, left ventricular end diastolic-pressure guided fluid administration and forced diuresis techniques.

SUMMARY

Despite an abundance of fluid administration trials, it is difficult to make definitive recommendations about preventive fluid administration strategies due to low scientific quality of published studies. The literature supports use of i.v. compared with no fluid administration, especially in high-risk patients undergoing intra-arterial contrast media exposure. Use of isotonic saline is recommended over 0.45% saline or isotonic sodium bicarbonate. Logistical considerations support shortened over longer i.v. fluid administration strategies, despite an absence of evidence of equivalent efficacy. Current literature does not support oral hydration for high-risk patients. The use of tailored fluid administration in heart failure patients and forced diuresis with matching fluid administration are promising new fluid administration strategies.

Optical Coherence Tomography: An Eye Into the Coronary Artery

Optical coherence tomography (OCT) is slowly but surely gaining a foothold in the hands of interventional cardiologists. Intraluminal and transmural contents of the coronary arteries are no longer elusive to the cardiologist's probing eye. Although the graduation of an interventionalist in imaging techniques right from naked eye angiographies to ultrasound-based coronary sonographies to the modern light-based OCT has been slow, with the increasing regularity of complex coronary cases in practice, such a transition is inevitable. Although intravascular ultrasound (IVUS) due to its robust clinical data has been the preferred imaging modality in recent years, OCT provides a distinct upgrade over it in many imaging and procedural aspects. Better image resolution, accurate estimation of the calcified lesion, and better evaluation of acute and chronic stent failure are the distinct advantages of OCT over IVUS. Despite the obvious imaging advantages of OCT, its clinical impact remains subdued. However, upcoming newer trials and data have been encouraging for expanding the use of OCT to wider indications in clinical utility. During percutaneous coronary intervention (PCI), OCT provides the detailed information (dissection, tissue prolapse, thrombi, and incomplete stent apposition) required for optimal stent deployment, which is the key to successfully reducing the major adverse cardiovascular event (MACE) and stent-related morbidities. The increasing use of OCT in complex bifurcation stenting involving the left main (LM) is being studied. Also, the traditional pitfalls of OCT, such as additional contrast load for image acquisition and stenting involving the ostial and proximal LM, have also been overcome recently. In this review, we discuss the interpretation of OCT images and its clinical impact on the outcome of procedures along with current barriers to its use and newer paradigms in which OCT is starting to become a promising tool for the interventionalist and what can be expected for the immediate future in the imaging world.

Three-Dimensional Kidney-on-a-Chip Assessment of Contrast-Induced Kidney Injury: Osmolality and Viscosity

Increased viscosity of concentrated contrast media (CM) in the renal tubules can perturb renal hemodynamics and have a detrimental effect on tubular epithelial cells. However, the effects of viscosity on contrast-induced nephropathy (CIN) remain poorly understood. Conventional in vitro culture studies do not reflect the rheological properties of CM. Therefore, we investigated the effects of CM viscosity on renal tubules using a kidney-on-a-chip and two different types of CM. Renal proximal tubule epithelial cells (RPTEC) were cultured in a three-dimensional microfluidic culture platform under bidirectional fluid shear stress. We treated the RPTEC with two types of CM: low- (LOCM, iopromide) and iso-osmolar contrast media (IOCM, iodixanol). Renal tubular cell injury induced by LOCM and IOCM was examined under different iodine concentrations (50–250 mgI/mL) and shear-stress conditions. LOCM showed a significant dose-dependent cytotoxic effect, which was significantly higher than that of IOCM under static and low-to-moderate shear stress conditions. However, high shear-stress resulted in reduced cell viability in IOCM; no difference between IOCM and LOCM was found under high shear-stress conditions. The cytotoxic effects were pronounced at a mean shear stress of 1 dyn/cm2 or higher. The high viscosity of IOCM slowed the fluid flow rate and augmented fluid shear-stress. We suggest an alternative in vitro model of CIN using the three-dimensional kidney-on-a-chip. Our results indicate a vital role of viscosity-induced nephrotoxicity under high shear-stress conditions, contrary to the findings of conventional in vitro studies.

Contrast-Associated Acute Kidney Injury

Contrast-associated acute kidney injury (CA-AKI) is an impairment of renal function, which occurs within days of intravascular administration of iodinated contrast media. Taking into account that minimally invasive cardiac interventions are becoming increasingly popular, compared to traditional surgery, given their impact on prognosis and costs, CA-AKI remains a subject of increasing interest for patients and physicians. This review summarizes the epidemiology and risk stratification, diagnostic criteria, pathophysiology and clinical implications of CA-AKI, providing evidence for the most studied preventive strategies.

Preparation and Characterization of Nanosuspensions of Triiodoaniline Derivative New Contrast Agent, and Investigation into Its Cytotoxicity and Contrast Properties

Iodine-based contrast agents have limitations such as rapid clearance, potential renal toxicity, non-specific blood pool distribution, headache, and adverse events. Nowadays, it is quite common to work with nanosized systems in order to eliminate the side effects of contrast agents. This study aims to synthesize a new iodinated contrast agent, prepare its nanosuspension by using the nanoprecipitation method, investigate its cytotoxicity, and compare its contrast properties with iohexol and iopromide through in-vitro experiments. The values of nanosuspension particle size and zeta potential have been found to be ~ 400 nm and ~ (-) 15 mV, respectively. In-vitro cellular viability findings indicated that the nanosuspension has lower cytotoxicity than the iohexol and iopromide. In the computed tomography (CT) imaging study of contrast features of nanosuspensions and two commercial agents, which involved 86 CT examinations using 31 parameters and two different devices, it was found that iodine had a stronger presence in its nanosuspension form than in iohexol and iopromide, which were the other two commercial contrast agents, when used in equal amounts. Thus in the case of nanosuspensions contrast brightness was achieved by using less iodine, while the same brightness could be obtained with higher doses of iohexol and iopromide. CT imaging therefore be done without much chemical use, which indicates that it may witness fewer side effects in the future.

Contrast-induced nephropathy in non-cardiac vascular procedures, a narrative review: Part 1

Contrast-induced nephropathy (CIN) is an important complication of iodinated contrast medium (CM) administration, which is associated with both short- and long-term adverse outcomes (e.g., cardiorenal events, longer hospital stay, and mortality). CIN has been mainly studied in relation to cardiac procedures, but it can also occur following non-cardiac vascular interventions. This is Part 1 of a narrative review summarizing the available literature on CIN after non-cardiac vascular diagnostic or therapeutic procedures for aortic aneurysm and carotid stenosis. We discuss the definition, pathophysiology, incidence, risk factors, biomarkers, and consequences of CIN in these settings, as well as preventive strategies and alternatives to limit iodinated CM use. Physicians and vascular surgeons should be aware of CM-related adverse events and the potential strategies to avoid them. Clearly, more research in this important field is required.

Tantalum oxide nanoparticles as an advanced platform for cancer diagnostics: a review and perspective

The development of new safe and effective contrast agents (CAs) is a crucial factor to increase the effectiveness of computed tomography (CT). For now, tantalum oxide-based nanoparticles (TaOx NPs) are among the most promising CAs for CT due to their superior properties: high X-ray attenuation coefficient, excellent biocompatibility, and easily modifiable surface chemistry. Compared to the commercially available analogs (iodine-based CAs), TaOx NPs provide better contrast performance, long-circulation, and high safety profiles (reduced exposure of X-rays and CA dosage). Among the investigated nanoparticulate CAs they afford higher cost-effectiveness (Au, Pt, Lu). TaOx NPs can also be easily modified to include other imaging or therapeutic modalities. This review aims to summarize the current state-of-the-art knowledge in the field of tantalum oxide-based CAs used for single or multimodal imaging and theranostic purposes. The design specification of TaOx NPs in terms of size, surface functionalization, composition, and their influence on the contrast performance, toxicity, and pharmacokinetics are discussed. Finally, the future opportunities and challenges of TaOx NPs used as CT CAs are addressed.

Magnetic resonance diffusion tensor imaging applied to rat model of contrast-induced acute kidney injury

Objectives

In this preclinical investigation, the feasibility of using diffusion tensor imaging (DTI) to study contrast-induced acute kidney injury (CIAKI) is explored, comparing radiographic outcomes with histopathologic and immunohistochemical findings after repeated animal exposures to iodinated contrast agent.

Materials and Methods

Forty-five male wistar rats were allocated to three groups (n = 15 each), each receiving two separate injections 1 day apart: group 1 (iodixanol then saline); group 2 (iodixanol twice); and control group (saline twice). Five rats were then randomly selected from each group at three separate time points (1 h, 24 h, and 120 h) for magnetic resonance imaging (MRI). Upon MRI completion, the animals were sacrificed, examining renal tissue and serum creatinine level. DTI data served to calculate fractional anisotropy (FA) and apparent diffusion coefficient (ADC).

Results

FA values were significantly lower in group 2 than in the others. Compared with controls, FA assessments at 1 h, 24 h, and 120 h after injections commenced were significantly lower in group 2; and ADC was significantly more pronounced at 24 h. Serum creatinine levels at 24 h were markedly elevated in both groups 1 and 2. Pearson correlation analysis revealed significant negative correlations between FA (r = −0.730; p < 0.05) or ADC (r = −0.827; p < 0.05) and tubular injury and between FA (r = −0.563; p < 0.05) or ADC (r = −0.805; p < 0.05) and hypoxia-inducible factor-1α.

Conclusions

Analytic approaches to DTI with better reproducibility should aid in monitoring the early pathophysiologic derangements of CIAKI, thus facilitating timely reversal of the detrimental effects.

Preventing a nonexistent entity: the curious case of contrast and acute kidney injury

PURPOSE OF REVIEW

In recent years, doubt has been cast on the existence of contrast-induced acute kidney injury. The skepticism has stemmed from observational studies from large administrative healthcare databases. Although they correctly call that contrast-induced acute kidney injury is less common than previously thought, they cannot completely exclude selection bias.

RECENT FINDINGS

Though less common than previously thought, contrast-induced acute kidney injury still exists. The only prophylactic method that remains valid is that of isotonic volume expansion, which is still deemed beneficial in high-risk patients. N-acetylcysteine and sodium bicarbonate are ineffective and their use should be abandoned.

SUMMARY

Contrast-induced kidney injury should be defined based on clinical grounds, not merely on biochemical numbers. More research to validate a clinical definition is necessary in order to accurately re-examine its incidence.

Saline as an alternative to radio-contrast for optical coherence tomography guided percutaneous coronary intervention: A prospective comparison

OBJECTIVES

To do a quantitative comparison of saline and contrast Frequency domain optical coherence tomography (FD-OCT) during percutaneous coronary intervention (PCI) optimisation.

METHODS

13 pairs of OCT runs were analysed, wherein each pair consisted of a contrast run and a heparinized saline run taken in the same coronary artery at the same position. Quantitative analysis was done comparing minimal lumen area (MLA), proximal reference diameter (PRD), distal reference diameter (DRD) and percentage area stenosis (AS) at the same anatomical location. Lesion morphologies, rendered stent view and 3D reconstruction were compared for image clarity.

RESULT

The saline OCT runs resulted in comparable MLA (3.88 ± 2.59 mm² with saline run vs 3.88 ± 2.71 mm² with contrast run; p = 0.650), PRD (3.66 ± 0.52 mm with saline vs 3.65 ± 0.52 mm with contrast; p = 0.463), DRD (2.97 ± 0.22 mm with saline vs 2.99 ± 0.88 mm with contrast; p = 0.433), and AS (59.60 ± 18.62% with saline vs 59.18 ± 19.11% with contrast; p = 0.753) with respect to the contrast runs. The Bland Altman plots of the measured parameters indicate good agreement between saline and contrast OCT. Linear regression analysis indicated the absence of proportional bias All lesion morphologies (calcified, fibrotic, thin cap fibroatheroma, macrophages, cholesterol crystals and edge dissection), 3D reconstruction and rendered stent view were clearly demonstrable in the saline OCT runs.

CONCLUSIONS

Using heparinized saline as flushing media in coronary FD-OCT may result in vessel dimensions that are comparable with contrast. Heparinized saline may be used as a contrast saving alternative for FD-OCT during PCI optimization.

Monitoring Renal Hemodynamics and Oxygenation by Invasive Probes: Experimental Protocol

Renal tissue hypoperfusion and hypoxia are early key elements in the pathophysiology of acute kidney injury of various origins, and may also promote progression from acute injury to chronic kidney disease. Here we describe methods to study control of renal hemodynamics and tissue oxygenation by means of invasive probes in anesthetized rats. Step-by-step protocols are provided for two setups, one for experiments in laboratories for integrative physiology and the other for experiments within small-animal magnetic resonance scanners.This publication is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers. This experimental protocol chapter is complemented by a separate chapter describing the basic concepts of quantitatively assessing renal perfusion and oxygenation with invasive probes.

Quantitative Assessment of Renal Perfusion and Oxygenation by Invasive Probes: Basic Concepts

Renal tissue hypoperfusion and hypoxia are early key elements in the pathophysiology of acute kidney injury of various origins, and may also promote progression from acute injury to chronic kidney disease. Here we describe basic principles of methodology to quantify renal hemodynamics and tissue oxygenation by means of invasive probes in experimental animals. Advantages and disadvantages of the various methods are discussed in the context of the heterogeneity of renal tissue perfusion and oxygenation.This chapter is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers. This introduction chapter is complemented by a separate chapter describing the experimental procedure and data analysis.

Reversible (Patho)Physiologically Relevant Test Interventions: Rationale and Examples

Renal tissue hypoperfusion and hypoxia are early key elements in the pathophysiology of acute kidney injury of various origins, and may also promote progression from acute injury to chronic kidney disease. Here we describe test interventions that are used to study the control of renal hemodynamics and oxygenation in experimental animals in the context of kidney-specific control of hemodynamics and oxygenation. The rationale behind the use of the individual tests, the physiological responses of renal hemodynamics and oxygenation, the use in preclinical studies, and the possible application in humans are discussed.This chapter is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers.

MRI Mapping of the Blood Oxygenation Sensitive Parameter T2* in the Kidney: Basic Concept

The role of hypoxia in renal disease and injury has long been suggested but much work still remains, especially as it relates to human translation. Invasive pO₂ probes are feasible in animal models but not for human use. In addition, they only provide localized measurements. Histological methods can identify hypoxic tissue and provide a spatial distribution, but are invasive and allow only one-time point. Blood oxygenation level dependent (BOLD) MRI is a noninvasive method that can monitor relative oxygen availability across the kidney. It is based on the inherent differences in magnetic properties of oxygenated vs. deoxygenated hemoglobin. Presence of deoxyhemoglobin enhances the spin-spin relaxation rate measured using a gradient echo sequence, known as R₂* (= 1/T₂*). While the key interest of BOLD MRI is in the application to humans, use in preclinical models is necessary primarily to validate the measurement against invasive methods, to better understand physiology and pathophysiology, and to evaluate novel interventions. Application of MRI acquisitions in preclinical settings involves several challenges both in terms of logistics and data acquisition. This section will introduce the concept of BOLD MRI and provide some illustrative applications. The following sections will discuss the technical issues associated with data acquisition and analysis.This chapter is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers. This introduction chapter is complemented by two separate chapters describing the experimental procedure and data analysis.

Study of saline optical coherence tomography-guided percutaneous coronary intervention (SOCT-PCI Study)

AIM

The aim of this study was to evaluate the feasibility of heparinised saline as flushing media for frequency-domain optical coherence tomography (FD-OCT) image acquisition during percutaneous coronary intervention (PCI) optimisation.

METHODS AND RESULTS

Twenty-seven patients undergoing FD-OCT-guided PCI were enrolled. Heparinised saline was injected into the coronary during FD-OCT image acquisition. A total of 118 runs were analysed for image quality and diagnostic value. FD-OCT runs were categorised as follows: good runs (GRs), clinically usable runs (CURs) and clinically not usable runs (NURs); GRs and CURs were combined as clinically effective runs (ERs). Saline FD-OCT enabled visualisation of all possible coronary lesions. Of the 118 runs analysed, 61%, 27.1%, 11.9% and 88.1% were GRs, CURs, NURs and ERs, respectively. Sixty-one percent of total runs were left coronary system (LCS) and 39% were right coronary system (RCS) runs. Among LCS runs, 55.6%, 30.6%, 13.8% and 86.2% were GRs, CURs, NURs and ERs, respectively. Among RCS runs, 69.6%, 21.7%, 8.7% and 91.3% were GRs, CURs, NURs and ERs, respectively.

CONCLUSION

This is the first study to demonstrate the technical feasibility of isolated saline FD-OCT for PCI optimisation.

Role of Hypoxia in Renal Failure Caused by Nephrotoxins and Hypertonic Solutions

Hypoxia plays a role in the pathogenesis of acute kidney injury under diverse clinical settings, including nephrotoxicity. Although some nephrotoxins exert direct renal parenchymal injury, likely with consequent altered oxygenation, others primarily reduce renal parenchymal oxygenation, leading to hypoxic tubular damage. As outlined in this review, nephrotoxin-related renal hypoxia may result from an altered renal oxygen supply (cyclosporine), enhanced oxygen consumption for tubular transport (agents inducing osmotic diuresis), or their combination (nonsteroidal anti-inflammatory drugs, radiocontrast agents, and others). Most agents causing hypoxic renal injury further supress physiologic low medullary Po₂, in which a limited regional blood supply barely matches the intense regional tubular transport and oxygen consumption. The medullary tubular transport and blood supply are finely matched, securing oxygen sufficiency. Predisposition to hypoxia-mediated nephrotoxicity by medical conditions, such as chronic kidney disease or diabetes, may be explained by malfunctioning of control systems that normally maintain medullary oxygenation. However, this propensity may be diminished by hypoxia-mediated adaptive responses governed by hypoxia-inducible factors. Recent reports have suggested that inhibitors of sodium-glucose cotransporters and the administration of hypertonic saline may be added to the growing list of common therapeutic interventions that intensify medullary hypoxia, and potentially could lead to hypoxic acute kidney injury.

Hydration: Intravenous and Oral: Approaches, Principals, and Differing Regimens: Is It What Goes in or What Comes Out That Is Important?

The literature (in English) was accessed to review the evidence that administration of fluids is protective of contrast-associated acute kidney injury (CA-AKI). The evidence was evaluated with the intent of understanding mechanisms of protection. Prospective randomized trials comparing oral versus intravenous fluid, sodium chloride versus no intravenous fluid, sodium bicarbonate versus sodium chloride, and forced matched hydration versus intravenous sodium chloride provided the data. In general, the more fluid administered, the lower the incidence of CA-AKI. However, understanding the mechanism of this beneficial effect suggests that it is the urine output that most directly affects the incidence of CA-AKI.

Contrast Media-Different Types of Contrast Media, Their History, Chemical Properties, and Relative Nephrotoxicity

History of contrast dates back to the 1890s, with the invention of the radiograph. Nephrotoxicity has been a main limitation in ideal contrast media (CM). High-osmolar contrast media no longer are in clinical use due to overwhelming evidence supporting greater nephrotoxicity with these CM compared with current CM. Contrast-induced nephropathy (CIN) remains a common cause of in-hospital acute kidney injury. The choice contrast agent is determined mainly by cost and institution practice. This review focuses on the history, chemical properties, and experimental and clinical studies on the various groups of CM and their role in CIN.

Probing renal blood volume with magnetic resonance imaging

Damage to the kidney substantially reduces life expectancy. Renal tissue hypoperfusion and hypoxia are key elements in the pathophysiology of acute kidney injury and its progression to chronic kidney disease. In vivo assessment of renal haemodynamics and tissue oxygenation remains a challenge. Blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) is sensitive to changes in the effective transversal relaxation time (T₂ *) in vivo, and is non-invasive and indicative of renal tissue oxygenation. However, the renal T₂ * to tissue pO₂ relationship is not governed exclusively by renal blood oxygenation, but is affected by physiological confounders with alterations in renal blood volume fraction (BVf) being of particular relevance. To decipher this interference probing renal BVf is essential for the pursuit of renal MR oximetry. Superparamagnetic iron oxide nanoparticle (USPIO) preparations can be used as MRI visible blood pool markers for detailing alterations in BVf. This review promotes the opportunities of MRI-based assessment of renal BVf. Following an outline on the specifics of renal oxygenation and perfusion, changes in renal BVf upon interventions and their potential impact on renal T₂ * are discussed. We also describe the basic principles of renal BVf assessment using ferumoxytol-enhanced MRI in the equilibrium concentration regimen. We demonstrate that ferumoxytol does not alter control of renal haemodynamics and oxygenation. Preclinical applications of ferumoxytol enhanced renal MRI as well as considerations for its clinical implementation for examining renal BVf changes are provided alongside practical considerations. Finally, we explore the future directions of MRI-based assessment of renal BVf.

Radiocontrast Toxicity

Intravenous and intraarterial contrast media are invaluable tools in the diagnosis of anatomic lesions. However, they have been associated with deleterious renal events, ranging from acute kidney injury (iodinated contrast) to nephrogenic systemic fibrosis (gadolinium-containing agents). Contrast-associated acute kidney injury has a wide incidence, likely due to differences in populations studied, with incidence likely overstated due to comorbid conditions at the time of contrast exposure. Pathophysiology includes hemodynamic and direct toxic effects. Preventative strategies include intravenous saline administration, higher urine pH, and statin administration. Importantly, because of fears of contrast-associated acute kidney injury, practitioners may be selecting only the healthiest patients for contrast exposure. Gadolinium-based contrast agents may cause their toxicity through being unbound from their ligand, and certain preparations may be less harmful than others.

Radiological iodinated contrast-induced nephropathy

The use of iodinated contrast media can cause renal toxicity. Whether contrast media are exclusively responsible for kidney damage is currently the subject of debate, given that in most cases, other potential causes of the renal failure are present. With current low-osmolar and iso-osmolar contrast media, the incidence rate of contrast-induced nephropathy is estimated to be <1% in the low-risk population but can increase to 37% in patients who are administered contrast by an intra-arterial administration and/or who have renal failure with an estimated glomerular filtration rate (eGFR) <30mL/min/1.73m². To minimize the risk of renal toxicity, the recommendation is to administer the least amount of contrast possible and ensure appropriate volume expansion by infusing 0.9% saline solution.

Zero contrast optical coherence tomography-guided percutaneous coronary intervention for in-stent restenosis of the saphenous vein graft using a non-contrast flush medium

Percutaneous coronary intervention (PCI) is often denied for individuals with coronary artery disease who are prone to develop contrast-induced acute kidney injury. We report a 73-year-old, stage 3 chronic kidney disease patient (CKD), who underwent coronary artery bypass surgery and saphenous vein graft (SVG) stenting in the past, presented with in-stent restenosis (ISR) of SVG stent. Zero contrast optical coherence tomography (OCT) guided–PCI was successfully performed using low molecular weight dextran-40 (LMWD-40) as the flush medium. Our report suggests the safety and feasibility of LMWD-40–based OCT-guided zero contrast PCI in ISR of SVG in a CKD patient, although further prospective studies are needed to evaluate this technique.

Predictors of contrast induced nephropathy and the applicability of the Mehran risk score in high risk patients undergoing coronary angioplasty-A study from a tertiary care center in South India

Objective

To study the incidence and predictors of Contrast induced nephropathy (CIN) in high risk patients undergoing coronary angioplasty. To study the applicability of the Mehran Risk Score (MRS) in the prediction of CIN in our population.

Methods

This was a prospective observational study where patients with an estimated glomerular filtration rate (eGFR) between 30 and 60 ml/mt undergoing elective percutaneous coronary intervention (PCI) over a period of 15 months were evaluated prospectively for the development of CIN. The patients who developed CIN were then analysed for the presence of specific risk factors. The patients were categorized into the 4 risk groups based on the MRS.

Results

100 high risk patients underwent PCI during the study period. The incidence of CIN was 29%. On multivariate analysis, the presence of anemia (p = 0.007), increased contrast volume usage (as defined by >5* B.Wt/S.cr) (p = 0.012) and usage of loop diuretics (p = 0.033) were independently found to confer a significant risk of CIN. In patients belonging to the high Mehran risk group (MRS10- 15) and very high risk group (MRS >15) the risk of CIN was 3 fold (OR: 3.055, 95% CI: 1.18–7.94, p = 0.022) and 24 fold (OR: 24, 95% CI: 2.53–228.28, p = 0.006) higher respectively when compared to intermediate and low risk patients (MRS <10).

Conclusion

The incidence of CIN in high risk patients undergoing PCI is substantially higher in our population compared to similar studies in the west. The MRS risk prediction is pertinent even in an Indian population.

Effect of Repeated Injection of Iodixanol on Renal Function in Healthy Wistar Rats Using Functional MRI

Purpose

To determine the optimal time interval of repeated intravenous injections of iodixanol in rat model and to identify the injury location and causes of renal damage in vivo.

Materials and Methods

Rats were randomly divided into Control group, Group 1 with one iodixanol injection, and Group 2 with two iodixanol injections. Group 2 was subdivided into 3 cohorts according to the interval between the first and second iodixanol injections as 1, 3, and 5 days, respectively. Blood oxygen level-dependent (BOLD) imaging and diffusion weighted imaging (DWI) were performed at 1 hour, 1 day, 3 days, 5 days, and 10 days after the application of solutions.

Results

Compared with Group 1 (7.2%), Group 2 produced a remarkable R2^⁎ increment at the inner stripe of the renal outer medulla by 15.37% (P = 0.012), 14.83% (P = 0.046), and 13.53% (P > 0.05), respectively, at 1 hour after repeated injection of iodixanol. The severity of BOLD MRI to detect renal hypoxia was consistent with the expression of HIF-1α and R2^⁎ was well correlated with HIF-1α expression (r = 0.704). The acute tubular injury was associated with urinary NGAL and increased significantly at 1 day.

Conclusions

Repetitive injection of iodixanol within a short time window can induce acute kidney injury, the impact of which on renal damage in rats disappears gradually 3–5 days after the injections.

Iodixanol versus iopromide in patients with renal insufficiency undergoing coronary angiography with or without PCI

BACKGROUND

The use of contrast agents during coronary angiography can result in contrast-induced nephropathy (CIN), particularly in patients with renal dysfunction. On the contrary, different contrast agents can induce different degree of changes in cardiac function. The objective of our meta-analysis was to compare the clinical safety of iso-osmolar contrast medium iodixanol to low-osmolar contrast medium iopromide in patients with renal insufficiency undergoing coronary angiography with or without percutaneous coronary intervention (PCI).

METHODS

We searched Medline, Embase, Cochrane Library, and reference lists to identify randomized controlled trials that compared iodixanol to iopromide with the incidence of CIN as an endpoint in renal impaired patients undergoing coronary angiography. Outcome measures were the incidence of CIN, absolute peak serum creatinine (Scr) increase from baseline and a composite of cardiovascular adverse events.

RESULTS

A total of 8 trials with 3532 patients were pooled; 1759 patients received iodixanol and 1773 patients received iopromide. There was no significant difference in the incidence of CIN (summary odds ratio [OR] 0.50, 95% confidence interval [CI] 0.19-1.35, P = .17) and peak Scr increase (mean difference -0.01 mg/dL, 95% CI -0.08 to 0.05, P = .69) when iodixanol was compared with iopromide. But iodixanol was associated with a statistically significant reduction in cardiovascular adverse events when compared with iopromide (OR 0.47, 95% CI 0.30-0.73, P = .0009).

CONCLUSIONS

Analysis of pooled data from 8 randomized controlled trials of iodixanol against iopromide in patients with renal insufficiency undergoing coronary angiography with or without PCI showed that iodixanol nonsignificantly reduced the incidence of CIN, but was associated with a significantly reduced risk of cardiovascular adverse events when compared with iopromide.

The Protective Effects of Enalapril Maleate and Folic Acid Tablets against Contrast-Induced Nephropathy in Diabetic Rats

Background

Renal vasoconstriction, oxidative stress, endothelial dysfunction, and apoptosis are the major causes of contrast-induced nephropathy (CIN). The aim of this study was to evaluate the protective effects of enalapril maleate and folic acid tablets on CIN in diabetic rats.

Methods

Thirty-two Sprague-Dawley rats were divided into four groups: CIN (C), CIN + enalapril maleate (CE), CIN + folic acid (CF), and CIN + enalapril maleate and folic acid tablets (CEF). CE, CF, and CEF rats were treated orally with enalapril maleate, folic acid, or enalapril maleate and folic acid tablets, respectively, for 5 days. CIN was induced in all groups followed by analyzed biochemical parameters, oxidative stress markers, endothelial dysfunction parameters, renal histopathology, and TUNEL staining.

Results

Serum creatinine, blood urea nitrogen, and malondialdehyde levels were lower in the CEF group than in the C group. Homocysteine, superoxide dismutase, glutathione peroxidase, and nitric oxide levels were higher in the CEF group than in the C group. Histopathology scores and percentage of apoptotic kidney cells in the CEF group were significantly decreased compared with those in the C group.

Conclusions

These results suggest that enalapril maleate and folic acid tablets have a protective effect against CIN in diabetic rats.

A Proposed Computed Tomography Contrast Agent Using Carboxybetaine Zwitterionic Tantalum Oxide Nanoparticles: Imaging, Biological, and Physicochemical Performance

OBJECTIVES

The aim of this study was to produce and evaluate a proposed computed tomography (CT) contrast agent based on carboxybetaine zwitterionic (CZ)-coated soluble tantalum oxide (TaO) nanoparticles (NPs). We chose tantalum to provide superior imaging performance compared with current iodine-based clinical CT contrast agents. We developed the CZ coating to provide biological and physical performance similar to that of current iodinated contrast agents. In addition, the aim of this study was to evaluate the imaging, biological, and physicochemical performance of this proposed contrast agent compared with clinically used iodinated agents.

MATERIALS AND METHODS

We evaluated CT imaging performance of our CZ-TaO NPs compared with that of an iodinated agent in live rats, imaged centrally located within a tissue-equivalent plastic phantom that simulated a large patient. To evaluate vascular contrast enhancement, we scanned the rats' great vessels at high temporal resolution during and after contrast agent injection. We performed several in vivo CZ-TaO NP studies in healthy rats to evaluate tolerability. These studies included injecting the agent at the anticipated clinical dose (ACD) and at 3 times and 6 times the ACD, followed by longitudinal hematology to assess impact to blood cells and organ function (from 4 hours to 1 week). Kidney histological analysis was performed 48 hours after injection at 3 times the ACD. We measured the elimination half-life of CZ-TaO NPs from blood, and we monitored acute kidney injury biomarkers with a kidney injury assay using urine collected from 4 hours to 1 week. We measured tantalum retention in individual organs and in the whole carcass 48 hours after injection at ACD. Carboxybetaine zwitterionic TaO NPs were synthesized and analyzed in detail. We used multidimensional nuclear magnetic resonance to determine surface functionality of the NPs. We measured NP size and solution properties (osmolality and viscosity) of the agent over a range of tantalum concentrations, including the high concentrations required for standard clinical CT imaging.

RESULTS

Computed tomography imaging studies demonstrated image contrast improvement of approximately 40% to 50% using CZ-TaO NPs compared with an iodinated agent injected at the same mass concentration. Blood and organ analyses showed no adverse effects after injection in healthy naive rats at 3 times the ACD. Retention of tantalum at 48 hours after injection was less than 2% of the injected dose in the whole carcass, which very closely matched the reported retention of existing commercial iodine-based contrast agents. Urine analysis of sensitive markers for acute kidney injury showed no responses at 1 week after injection at 3 times the ACD; however, a moderate response in the neutrophil gelatinase-associated lipocalin biomarker was measured at 24 and 48 hours. Compared with other TaO NPs reported in the literature, CZ-TaO NPs had relatively low osmolality and viscosity at concentrations greater than 200 mg Ta/mL and were similar in these physical properties to dimeric iodine-based contrast agents.

CONCLUSIONS

We found that a CZ-TaO NP-based contrast agent is potentially viable for general-purpose clinical CT imaging. Our results suggest that such an agent can be formulated with clinically viable physicochemical properties, can be biologically safe and cleared rapidly in urine, and can provide substantially improved image contrast at CT compared with current iodinated agents.

Effect of ligustrazine on preventing contrast-induced nephropathy in patients with unstable angina

Objective

Our purpose was to assess the effect of ligustrazine in the prevention of contrast-induced nephropathy (CIN) in patients with unstable angina (UA).

Methods

148 patients with UA undergoing coronary angiography and/or percutaneous coronary intervention (PCI) were selected for observation; the patients were divided into a control group (group A, n=74) and a ligustrazine group (group B, n=74). Group A was given routine treatment, while group B was given routine treatment combined with ligustrazine. Serum creatinine (Scr), cystatin C and glomerular filtration rate (eGFR) concentrations were measured before and 1 day, 2 days and 3 days after treatment, and the incidence of contrast-induced nephropathy (CIN) and major cardiovascular events (MACE) were observed in both groups.

Results

The Scr, Cystatin C and eGRF levels in group B were better than in group A after 1 day (OR: 2.64, 95% CI: 2.47-4.98; OR: 2.66, 95% CI: 2.62-5.77; OR: 4.02, 95% CI: 3.02-5.53, respectively), 2 days (OR: 3.58, 95% CI: 2.41-4.92; OR: 2.92, 95% CI: 2.83-5.02; OR: 3.28, 95% CI: 3.24-5.14, respectively) and 3 days of treatment (OR: 3.26, 95% CI: 2.17-4.35; OR: 2.85, 95% CI: 2.26-4.02; OR: 3.19, 95% CI: 2.53-4.34, respectively). The incidence of CIN (9.26% vs 16.67%) and MACE (7.41% vs 18.51%) of group B were significantly lower than in group A (P<0.05).

Conclusions

Our study suggests that ligustrazine can reduce CIN and MACE in patients with UA when undergoing coronary angiography and/or PCI.

Cancer and the kidney: dangereoux liasons or price paid for the progress in medicine?

A long time ago, the links between renal disease and malignancy were observed, however, quite recently, their importance was recognized and 'new' subspecialty in nephrology, namely 'onconephrology' was established. In the XXI century, patients with malignancy make up the most growing number of the subjects seen for nephrology consult and/or critical care nephrology services. A plethora of renal problems may be found in patients with malignancy. They may influence not only their short-term outcomes but also the adequate therapy of the underlying oncological problem. Thus, all these kidney-related issues pose an important challenge for both specialities: oncology and nephrology. In the review a spectrum of acute and chronic renal injury caused by the malignancy is presented as well as the associations between renal disease and cancer. Assessment of kidney function and its importance in patients with malignancy is also discussed as medical oncologists should check the appropriate dose of chemotherapeutic drugs in relation to the actual renal function before prescribing them to the patients. Moreover, effects of kidney function on outcomes in oncology is presented. In addition, nephrology services should better understand both the biology of malignancy with its treatment to become a valuable part treating team to yield the best possible outcome. It is important for nephrology services to be acknowledged and to take an active participation in care of oncology patients.

Contrast-induced nephropathy: Basic concepts, pathophysiological implications and prevention strategies

Contrast-induced nephropathy (CIN) is reversible acute renal failure observed following administration of iodinated contrast media (CM) during angiographic or other medical procedures such as urography. There are various mechanisms through which CM develop their nephrotoxic effects, including oxidative stress and apoptosis. CIN is a real-life, albeit not very rare, entity. Exact pathophysiology remains obscure and no standard diagnostic criteria apply. The Acute Kidney Injury Network criteria was recently employed but its incidence/clinical significance warrants further clarification based on recent methodological advancements, because most published studies to date were contaminated by bias. The current study is a comprehensive review conducted to provide an overview of the basic concepts of CIN and summarize recent knowledge on its pathophysiology and the evidence supporting potential prevention strategies. CIN is expected to increase morbidity, hospital stay and mortality, while all patients scheduled to receive CM should undergo risk assessment for CIN and high-risk patients may be considered candidates for prevention strategies. The value of using compounds with antioxidant properties other than sodium bicarbonate, remains controversial, warranting further clinical investigation.

Application of BOLD MRI and DTI for the evaluation of renal effect related to viscosity of iodinated contrast agent in a rat model

PURPOSE

To evaluate the effects of viscosity of contrast agent (CA) on intrarenal oxygenation and diffusion as measured by blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) in a rat model.

MATERIALS AND METHODS

Radiocontrast iodixanol formulated in three viscosities were designated 270, 320, and 350 (mg iodine/mL). Sixty-three male Wistar rats were divided into four groups. Saline and iodixanol (4 g iodine/kg) were administered. MR images were acquired on a 3.0T scanner at baseline and at 1 hour, 24 hours, 48 hours, and 72 hours postinjection of solutions. BOLD-MRI was performed with a multiple gradient-recalled-echo sequence. The changes in R2*, apparent diffusion coefficient (ADC), fractional anisotropy (FA), histology, and hypoxia-inducible factor-1α (HIF-1α) immunoexpression were evaluated. The R2*, ADC, and FA values were normalized to baseline to calculate ΔR2*, ΔADC, and ΔFA.

RESULTS

Compared with baseline levels, distinct elevation of ΔR2* (P < 0.05) and obvious decrease in ΔADC (P < 0.01) and ΔFA (P < 0.05) were observed in all the anatomical compartments at 1 hour after administration of CA. The absolute values in ΔR2*, ΔADC, and ΔFA increased with increases in CA viscosity, and differed significantly between the CA groups in renal cortex (CO), outer stripe of outer medulla (OSOM), and inner stripe of outer medulla (ISOM) (all P < 0.05). A significant positive correlation was observed between ΔR2* and HIF-1α expression (P < 0.001, r = 0.75). Significant negative correlations were observed between ΔADC, ΔFA, and pathologies in CO, OSOM, ISOM (all P < 0.001, r = -0.68-0.87; all P < 0.001, r = -0.60-0.66).

CONCLUSION

The effect of CA viscosity on intrarenal oxygenation and diffusion was viscosity-dependent, and was identified using BOLD-MRI and DTI.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:1320-1331.

Application of low dose radiation and low concentration contrast media in enhanced CT scans in children with congenital heart disease

OBJECTIVE

The aim of this study was to explore the feasibility of using low dose radiation and low concentration contrast media in enhanced CT examinations in children with congenital heart disease.

MATERIALS AND METHODS

Ninety patients with congenital heart disease were randomly divided into three groups of 30 patients each who underwent contrast-enhanced cardiac scans on a Discovery CT750 HD scanner. Group A received 270 mg I/mL iodixanol, and group B received 320 mg I/mL iodixanol contrast media and was scanned with prospective ECG triggering mode. Group C received 320 mg I/mL iodixanol and was scanned with conventional retrospective ECG gating mode. The same weight-based contrast injection protocol was used for all three groups. Images were reconstructed using a 30% adaptive statistical iterative reconstruction (ASIR) algorithm and a 50% ASIR in groups A and B and a 30% ASIR in group C. The subjective and objective image quality evaluations, diagnostic accuracies, radiation doses and amounts of contrast media in the three groups were measured and compared.

RESULTS

All images in the three groups met the diagnostic requirements, with the same diagnostic accuracy and image quality scores greater than 3 in a 4-point scoring system. However, ventricular enhancement and the objective noise, signal-to-noise ratio, contrast-to-noise ratio and subjective image quality scores in group C were better than those in groups A and B (all P<.001). The effective radiation dose in groups A and B was 84% lower than that in group C (P<.001); group A received the lowest contrast dose (14% lower than that of groups B and C).

CONCLUSION

Enhanced CT scan images with low dose radiation and low concentration contrast media can meet the diagnostic requirements for examining children with congenital heart disease while reducing the potential risk of radiation damage and contrast-induced nephropathy.

Acute kidney damage induced by low- and iso-osmolar contrast media in rats: Comparison study with physiologic MRI and histologic-gene examination

PURPOSE

To investigate the physiopathological effects of low- and iso-osmolar contrast media (CM) on renal function with physiologic MRI and histologic-gene examination.

MATERIALS AND METHODS

Forty-eight rats underwent time-course DWI and DCE-MRI at 3.0 Tesla (T) before and 5-15 min after exposure of CM or saline (Iop.370: 370 mgI/mL iopromide; Iod.320: 320 mgI/mL iodixanol; Iod.270: 270 mgI/mL iodixanol; 4 gI/kg body weight). Intrarenal viscosity was reflected by apparent diffusion coefficient (ADC). Renal physiologies were evaluated by DCE-derived glomerular filtration rate (GFR), renal blood flow (RBF), and renal blood volume (RBV). Potential acute kidney injury (AKI) was determined by histology and the expression of kidney injury molecule 1 (Kim-1).

RESULTS

Iop.370 mainly increased ADC in inner-medulla (△ADC_IM : 12.3 ± 11.1%; P < 0.001). Iod.320 and Iod.270 mainly decreased ADC in outer-medulla (△ADC_IM ; Iod.320: 16.8 ± 7.5%; Iod.270: 18.1 ± 9.5%; P < 0.001) and inner-medulla (△ADC_IM ; Iod.320: 28.4 ± 9.3%; Iod.270: 30.3 ± 6.3%; P < 0.001). GFR, RBF and RBV were significantly decreased by Iod.320 (△GFR: 45.5 ± 24.1%; △RBF: 44.6 ± 19.0%; △RBV: 35.2 ± 10.1%; P < 0.001) and Iod.270 (33.2 ± 19.0%; 38.1 ± 15.6%; 30.1 ± 10.1%; P < 0.001), while rarely changed by Iop.370 and saline. Formation of vacuoles and increase in Kim-1 expression was prominently detected in group of Iod.320, while rarely in Iod.270 and Iop.370.

CONCLUSION

Iso-osmolar iodixanol, given at high-dose, produced prominent AKI in nonhydrated rats. This renal dysfunction could be assessed noninvasively by physiologic MRI.

LEVEL OF EVIDENCE

1 J. Magn. Reson. Imaging 2017;45:291-302.