The Controversy of Contrast-Induced Nephropathy With Intravenous Contrast: What Is the Risk?

Low KeV virtual monoenergetic images for detecting low dose iodine- or alternative Gd-based IV contrast agents

Background

The recent shortage of iodine-based intravenous contrast and its cost highlight the need for limiting dose and alterative agents.

Purpose

To quantify radiodensity (Hounsfield Units, HU) improvement and potential iodine dose reduction with low keV imaging compared to conventional polyenergetic reconstructions on dual source (DSCT) and dual layer (DLCT) CT and to assess potential utility of non-iodine gadolinium-alternatives with low keV imaging.

Materials and methods

This phantom study used dilutions of three commercially-available contrast agents scanned by DSCT and DLCT. Conventional polyenergetic and virtual monoenergetic images (VMI) were reconstructed of each of five dilutions at five keV levels. HU and signal-to-noise ratios were compared among iodine- and gadolinium-based contrast agents.

Results

Iodine- and gadolinium-based contrast agent HU increased inversely to keV for the same dilution in both scanners. At the lowest keV setting (40 keV), iodine-based contrast agent HU in VMIs with DLCT and DSCT were approximately 300 % and 400 % of conventional, respectively. Gd-based contrast agent HU in VMIs at low keV were similar to or better than conventional iodine HU. Comparing the dual energy CTs, although HU from iodine and gadolinium-based contrast agents for conventional polyenergetic reconstructions was similar, HU in VMIs of DSCT were right shifted compared to DLCT by ∼10 keV lower.

Conclusion

Depending on CT scanner type, 1/3 to 1/4 dose of iodinated contrast at 40 keV provides HU similar to full dose conventional acquisition, suggesting 1/3-1/4 dose may be adequate clinically at 40 keV. Depending on the Gd-based contrast and CT type, Gd-based contrast at 40 keV provides similar or greater HU compared to conventional acquisitions with iodinated contrast, suggesting Gd-based contrast at 40 keV may serve as an alternative to iodinated contrast. HU on VMI images is scanner dependent, suggesting scanner-dependent protocol optimization and potentially monoenergy HU calibration between scanners is needed.

Effect of Serum Bilirubin Levels on Contrast-induced Acute Kidney Injury: A Systematic Evaluation and Meta-analysis

Contrast-induced acute kidney injury (CI-AKI) is an important complication following the use of iodinated contrast media. Bilirubin has a protective effect but may also aggravate CI-AKI. The purpose of this systematic review was to assess whether bilirubin is a risk factor for CI-AKI. We searched the databases PubMed, Embase, Web of Science, Cochrane Library, Scopus, Ovid Medline, CNKI (China National Knowledge Infrastructure), VPCS (Vip Paper Check System), Wanfang, and CBM (Chinese BioMedical Literature Database) from the initial date to May 6, 2023. We summarized the results by directly combining the effect-size odds ratio (OR) and 95% confidence interval (CI) and identified sources of heterogeneity through subgroup analysis, sensitivity analysis, and meta-regression analysis. A total of 10 studies (14 data sets) were included: 7 retrospective studies (10 data sets) and 3 prospective studies (4 data sets), involving 12776 participants. The incidence of CI-AKI of 16% (95% CI: 14-19%). Total bilirubin was positively associated with the occurrence of CI-AKI (OR = 1.80; 95% CI: 1.36-2.38). Both low and high bilirubin concentrations were risk factors for CI-AKI. The incidence of CI-AKI was higher in the low bilirubin group than in the high bilirubin group.

Evaluating the incidence and risk factors for developing acute tubular necrosis after percutaneous coronary intervention in the management of coronary artery dissection

BACKGROUND

Coronary artery dissection is managed primarily conservatively with serial imaging or percutaneous coronary intervention (PCI). Exposure to contrast in either modality could potentially result in acute tubular necrosis (ATN). However, no data compares ATN incidence in these management strategies. This study compares the incidence of ATN and associated mortality of PCI and conservative management of coronary artery dissection.

METHODS

A retrospective analysis was performed using data from the National Inpatient Sample database, including patients with coronary artery dissection between 2016 through 2020. We analyzed the incidence of ATN and associated mortality of PCI and conservative management of coronary artery dissection.

RESULTS

We found that the odds of developing ATN were 22% lower in patients managed with PCI than those managed conservatively. There was no difference in the in-hospital mortality or hospital length of stay between the two groups but the mortality rate in patients with ATN was double that of those who did not develop ATN in both PCI and conservatively managed groups.

CONCLUSIONS

The higher incidents of ATN in patients with coronary dissection being managed with conservative measures compared to PCI suggest that the use of CTA may be harmful. Additionally, persons who developed ATN may have higher mortality. Therefore, more studies in the management of coronary artery dissection need to be done which would allow further steps to be taken to reduce this harm.

[Cancer imaging and prevention of renal failure]

The risk of acute renal failure (ARF) following iodinated contrast media injection has long been overestimated because of the previous use of more toxic ICPs and uncontrolled studies. Nowadays, this concept is being questioned. Patients with severe renal failure and/or ARF are the only group still considered at risk. In these patients, it is necessary to discuss an alternative without an iodinated contrast agent. Contrast-enhanced ultrasound, MRI, spectral CT or PET-CT scan can be used instead of contrast-enhanced CT. Preventive measures should be applied when appropriate substitute to CT is not available or not diagnosed (minimum necessary dose of ICP, interruption of some treatments and prior hydration). These recommendations formalized by the European Society of Urogenital Radiology (ESUR) in 2018 address most situations faced by clinicians. In complex situations, an opinion from a nephrologist remains necessary after asking the radiologist about the availability of acceptable substitutes.

Drug stewardship in chronic kidney disease to achieve effective and safe medication use

People living with chronic kidney disease (CKD) often experience multimorbidity and require polypharmacy. Kidney dysfunction can also alter the pharmacokinetics and pharmacodynamics of medications, which can modify their risks and benefits; the extent of these changes is not well understood for all situations or medications. The principle of drug stewardship is aimed at maximizing medication safety and effectiveness in a population of patients through a variety of processes including medication reconciliation, medication selection, dose adjustment, monitoring for effectiveness and safety, and discontinuation (deprescribing) when no longer necessary. This Review is aimed at serving as a resource for achieving optimal drug stewardship for patients with CKD. We describe special considerations for medication use during pregnancy and lactation, during acute illness and in patients with cancer, as well as guidance for the responsible use of over-the-counter drugs, herbal remedies, supplements and sick-day rules. We also highlight inequities in medication access worldwide and suggest policies to improve access to quality and essential medications for all persons with CKD. Further strategies to promote drug stewardship include patient education and engagement, the use of digital health tools, shared decision-making and collaboration within interdisciplinary teams. Throughout, we position the person with CKD at the centre of all drug stewardship efforts.

Reduction of contrast medium for transcatheter aortic valve replacement planning using a spectral detector CT: a prospective clinical trial

INTRODUCTION

This study investigated the use of dual-energy spectral detector computed tomography (CT) and virtual monoenergetic imaging (VMI) reconstructions in pre-interventional transcatheter aortic valve replacement (TAVR) planning. We aimed to determine the minimum required contrast medium (CM) amount to maintain diagnostic CT imaging quality for TAVR planning.

METHODS

In this prospective clinical trial, TAVR candidates received a standardized dual-layer spectral detector CT protocol. The CM amount (Iohexol 350 mg iodine/mL, standardized flow rate 3 mL/s) was reduced systematically after 15 patients by 10 mL, starting at 60 mL (institutional standard). We evaluated standard, and 40- and 60-keV VMI reconstructions. For image quality, we measured signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and diameters in multiple vessel sections (i.e., aortic annulus: diameter, perimeter, area; aorta/arteries: minimal diameter). Mixed regression models (MRM), including interaction terms and clinical characteristics, were used for comparison.

RESULTS

Sixty consecutive patients (mean age, 79.4 ± 7.5 years; 28 females, 46.7%) were included. In pre-TAVR CT, the CM reduction to 40 mL is possible without affecting the image quality (MRM: SNR: -1.1, p = 0.726; CNR: 0.0, p = 0.999). VMI 40-keV reconstructions showed better results than standard reconstructions with significantly higher SNR (+ 6.04, p < 0.001). Reduction to 30 mL CM resulted in a significant loss of quality (MRM: SNR: -12.9, p < 0.001; CNR: -13.9, p < 0.001), regardless of the reconstruction. Across the reconstructions, we observed no differences in the metric evaluation (p > 0.914).

CONCLUSION

Among TAVR candidates undergoing pre-interventional CT at a dual-layer spectral detector system, applying 40 mL CM is sufficient to maintain diagnostic image quality. VMI 40-keV reconstructions improve the vessel attenuation and are recommended for evaluation.

CLINICAL RELEVANCE STATEMENT

Contrast medium reduction to 40 mL in pre-interventional transcatheter aortic valve replacement CT using dual-energy CT maintains image quality, while 40-keV virtual monoenergetic imaging reconstructions enhance vessel attenuation. These results offer valuable recommendations for interventional transcatheter aortic valve replacement evaluation and potentially improve nephroprotection in patients with compromised renal function.

KEY POINTS

• Patients undergoing transcatheter aortic valve replacement (TAVR), requiring pre-interventional CT, are often multimorbid with impaired renal function. • Using a spectral detector dual-layer CT, contrast medium reduction to 40 mL is feasible, maintaining diagnostic image quality. • The additional application of virtual monoenergetic image reconstructions with 40 keV improves vessel attenuation significantly in clinical practice.

The relationship between perioperative serum albumin and contrast-induced acute kidney injury in patients after percutaneous coronary intervention

OBJECTIVE

Contrast-induced acute kidney injury (CI-AKI) is a common complication in patients undergoing percutaneous coronary intervention (PCI). Studies have shown that perioperative serum albumin levels may play a role in the occurrence of CI-AKI. In this study, we aimed to investigate the effect of perioperative serum albumin (delta albumin or &Alb) levels on the occurrence and long-term prognosis of CI-AKI patients after PCI.

METHODS

A total of 959 patients who underwent PCI between January 2017 and January 2019 were selected for this study. A receiver operating characteristic curve was used to determine the optimal cut-off value of the &Alb level for predicting CI-AKI after PCI. Patients were divided into two groups based on the optimal cut-off value: the high &Alb group (&Alb ≥ 4.55 g/L) and the control group (&Alb < 4.55 g/L). The incidences of CI-AKI and major adverse cardiac events (MACEs, including all-cause death, nonfatal myocardial infarction, and target vessel revascularization) were compared between the groups. Cox regression analysis was used to identify predictors of long-term prognosis after PCI.

RESULTS

Of the 959 patients, 147 (15.3%) developed CI-AKI after PCI. The CI-AKI group had a greater level of &Alb than did the non-CI-AKI group [(6.14 (3.90-9.10) versus 3.48 (4.31-6.57), P < 0.01)]. The incidence of CI-AKI in the high &Alb group was significantly greater than that in the low group (23.6% versus 8.3%, P < 0.01). After a 1-year follow-up, the incidence of MACEs was significantly greater in the high &Alb group than in the low group (18.6% versus 14.5%, P = 0.030). Cox regression analysis confirmed that CI-AKI was an independent predictor of MACEs at the 1-year follow-up (HR 1.43, 95% CI 1.04-1.96, P = 0.028). In addition, patients with low preoperative serum albumin levels had s significantly greater incidence of MACEs than did those with high preoperative serum albumin levels (23.2% versus 19.5%, P = 0.013).

CONCLUSION

In summary, high baseline &Alb levels are an independent risk factor for CI-AKI in patients after PCI. The occurrence of CI-AKI in the perioperative period is also an independent predictor of long-term prognosis after PCI. These findings highlight the importance of monitoring &Alb levels and taking steps to prevent CI-AKI in patients undergoing PCI.

Controllable synthesis of barium carbonate nano- and microparticles for SPECT and CT imaging

The design and synthesis of nano- and microcarriers for preclinical and clinical imaging are highly attractive due to their unique features, for example, multimodal properties. However, broad translation of these carriers into clinical practice is postponed due to the unknown biological reactivity of the new components used for their synthesis. Here, we have developed microcarriers (∼2-3 μm) and  nanocarriers (<200 nm) made of barium carbonate (BaCO3) for multiple imaging applications in vivo. In general, barium in the developed carriers can be used for X-ray computed tomography, and the introduction of a diagnostic isotope (99mTc) into the BaCO3 structure enables in vivo visualization using single-photon emission computed tomography. The bioimaging has shown that the radiolabeled BaCO3 nano- and microcarriers had different biodistribution profiles and tumor accumulation efficiencies after intratumoral and intravenous injections. In particular, in the case of intratumoral injection, all the types of used carriers mostly remained in the tumors (>97%). For intravenous injection, BaCO3 microcarriers were mainly localized in the lung tissues. However, BaCO3 NPs were mainly accumulated in the liver. These results were supported by ex vivo fluorescence imaging, direct radiometry, and histological analysis. The BaCO3-based micro- and nanocarriers showed negligible in vivo toxicity towards major organs such as the heart, lungs, liver, kidneys, and spleen. This study provides a simple strategy for the design and fabrication of the BaCO3-based carriers for the development of dual bioimaging.

Effect of Carvedilol Versus Metoprolol on Contrast-Induced Nephropathy in Patients with Acute Coronary Syndrome Undergoing Percutaneous Intervention Therapy

Carvedilol can inhibit inflammation, vasoconstriction, and oxidative stress, which play important roles in the development and progression of contrast-induced nephropathy (CIN). To the best of our knowledge, no studies have investigated the potential effect of carvedilol on the prevalence of CIN after percutaneous coronary intervention (PCI) for acute coronary syndrome (ACS). The present study aimed to determine whether carvedilol use is associated with the development of CIN. A total of 319 patients (mean age, 59.2 ± 12.4 years; 77.7% male) with ACS who underwent urgent PCI at our institution between May 2019 and May 2022 were included prospectively. Overall, 100 and 219 patients were assigned to the carvedilol and metoprolol groups, respectively. The prevalence of CIN was significantly lower in the carvedilol group (6.0%) than in the metoprolol group (18.3%; P = .003). Multivariate analysis revealed that carvedilol use (odds ratio [OR] .250, 95% confidence interval [CI] .092-.677, P = .006), amount of contrast agent (OR 1.004, 95% CI 1.000-1.008, P = .031), and admission estimated glomerular filtration rate (OR .978, 95% CI 0.960-.995, P = .014) were independently associated with the development of CIN. The use of carvedilol may be a promising option for the prevention of CIN in patients with ACS undergoing urgent PCI.

Image quality of abdominal photon-counting CT with reduced contrast media dose: Evaluation of reduced contrast media protocols during the COVID19 pandemic supply shortage

Rationale and objectives

Aim of this study was to assess the impact of contrast media dose (CMD) reduction on diagnostic quality of photon-counting detector CT (PCD-CT) and energy-integrating detector CT (EID-CT).

Methods

CT scans of the abdominal region with differing CMD acquired in portal venous phase on a PCD-CT were included and compared to EID-CT scans. Diagnostic quality and contrast intensity were rated. Additionally, readers had to assign the scans to reduced or regular CMD. Regions-of-interest (ROIs) were placed in defined segments of portal vein, inferior vena cava, liver, spleen, kidneys, abdominal aorta and muscular tissue. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated.

Results

Overall 158 CT scans performed on a PCD-CT and 68 examinations on an EID-CT were analyzed. Overall diagnostic quality showed no significant differences for PCD-CT with standard CMD which scored a median 5 (IQR:5-5) and PCD-CT with 70% CMD scoring 5 (4-5). (For PCD-CT, 71.69% of the examinations with reduced CMD were assigned to regular CMD by the readers, for EID-CT 9.09%. Averaged for all measurements SNR for 50% CMD was reduced by 19% in PCD-CT (EID-CT 34%) and CNR by 48% (EID-CT 56%). Virtual monoenergetic images (VMI)50keV for PCD-CT images acquired with 50% CMD showed an increase in SNR by 72% and CNR by 153%.

Conclusions

Diagnostic interpretability of PCD-CT examinations with reduction of up to 50% CMD is maintained. PCD-CT deducted scans especially with 70% CMD were often not recognized as CMD reduced scans. Compared to EID-CT less decline in SNR and CNR is observed for CMD reduced PCD-CT images. Employing VMI50keV for CMD-reduced PCD-CT images compensated for the effects.

The Treatment of Coronary Artery Disease in Patients with Chronic Kidney Disease: Gaps, Challenges, and Solutions

Background

Chronic kidney disease (CKD) is associated with a high burden of coronary artery disease (CAD), which remains the leading cause of death in CKD patients. Despite the high cardiovascular risk, ACS patients with renal dysfunction are less commonly treated with guideline-based medical therapy and are less frequently referred for coronary revascularization.

Summary

The management of CAD is more challenging in patients with CKD than in the general population due to concerns regarding side effects and renal toxicity, as well as uncertainty regarding clinical benefit of guideline-based medical therapy and interventions. Patients with advanced CKD and especially those receiving dialysis have not traditionally been represented in randomized trials evaluating either medical or revascularization therapies. Thus, only scant data from small prospective studies or retrospective analyses are available. Recently published studies suggest that there are significant opportunities to substantially improve both cardiovascular and renal outcomes of patients with CAD and CKD, including new medications and interventions. Thus, the objective of this review is to summarize the current evidence regarding the management of CAD in CKD patients, in particular with respect to improvement of both cardiovascular and renal outcomes.

Key Messages

Adequate medical therapy and coronary interventions using evidence-based strategies can improve both cardiac and renal outcomes in patients with CAD and CKD.

Prevention of contrast-associated acute kidney injury in an era of increasingly complex interventional procedures

Radiological and interventional cardiology procedures are in continuous expansion, leading to an important increase in the incidence of contrast-associated acute kidney injury (CA-AKI). Although numerous methods of CA-AKI prevention have been studied, at present, there is no consensus on the definition of this entity or on its prevention. In this paper, we aim to provide a critical analysis of the existing data on the epidemiology, pathophysiology, and clinical significance of CA-AKI. Existing and emergent approaches for CA-AKI prevention are also discussed, with a focus on parenteral fluid administration and on the most recent clinical and experimental data. We also emphasize a number of questions that remain to be answered, and we identify hotspots for future research.

The Effects of Coenzyme Q10 on Contrast-Induced Acute Kidney Injury in Type 2 Diabetes: A Randomized Clinical Trial

Contrast-induced acute kidney injury (CI-AKI) is a frequent challenge following the injection of contrast media and its subsequent oxidative stress. The aim of the present study was to evaluate the preventive effects of coenzyme Q10 (Q10), as a mitochondrial-targeted antioxidant in CI-AKI in diabetic patients, who account for a large proportion of angiographic cases. A total of 118 diabetic patients were randomly assigned to receive 120 mg of oral coenzyme Q10 (Q10 group) or placebo (Placebo group) for four days, starting 24 hours before contrast media injection. Blood urea nitrogen (BUN), serum and urinary creatinine, estimated glomerular filtration rate (eGFR), urinary malondialdehyde (UMDA), urinary total antioxidant capacity (UTAC), and urinary mitochondrial to nuclearDNA ratios (mtDNA/nDNA ratio) were evaluated before and after the treatment period. Urine sediments were also evaluated to report the urine microscopy score (UMS).The levels of BUN, serum and urine creatinine, and UMS were similar in the Q10 and placebo groups. EGFR was lower in the Q10 group before the treatment (p=0.013) but not after. The urinary mtDNA/nDNA ratio was 3.05±1.68 and 3.69±2.58 in placebo and Q10 groups, but UTAC was found to be lower in Q10 both before (p=0.006) and after the treatment (p<0.001). The incidence of CI-AKI was 14.40% and the mtDNA/nNDA ratio was similar between CI-AKI and non-CI-AKI patients. In conclusion, Q10 treatment shows no favorable effect on prevention of CI-AKI or a urinary mtDNA/nDNA ratio among diabetic patients.

Berberine alleviates contrast-induced nephropathy by activating Akt/Foxo3a/Nrf2 signalling pathway

Contrast-induced nephropathy (CIN) is a condition that causes kidney damage in patients receiving angiography with iodine-based contrast agents. This study investigated the potential protective effects of berberine (BBR) against CIN and its underlying mechanisms. The researchers conducted both in vivo and in vitro experiments to explore BBR's renal protective effects. In the in vivo experiments, SD rats were used to create a CIN model, and different groups were established. The results showed that CIN model group exhibited impaired renal function, severe damage to renal tubular cells and increased apoptosis and ferroptosis. However, BBR treatment group demonstrated improved renal function, decreased apoptosis and ferroptosis. Similar results were observed in the in vitro experiments using HK-2 cells. BBR reduced ioversol-induced apoptosis and ferroptosis, and exerted its protective effects through Akt/Foxo3a/Nrf2 signalling pathway. BBR administration increased the expression of Foxo3a and Nrf2 while decreasing the levels of p-Akt and p-Foxo3a. In conclusion, this study revealed that BBR effectively inhibited ioversol-induced apoptosis and ferroptosis in vivo and in vitro. The protective effects of BBR were mediated through the modulation of Akt/Foxo3a/Nrf2 signalling pathway, leading to the alleviation of CIN. These findings suggest that BBR may have therapeutic potential for protecting against CIN in patients undergoing angiography with iodine-based contrast agents.

Severe Contrast-Induced Nephropathy Leading to Dialysis Occurring in a Patient with Near-Normal Baseline Creatinine Undergoing CT Angiography Using Intravenous Contrast Only

Contrast-induced nephropathy can be a major health issue in patients undergoing iodinated contrast exposure. Recently a published paper misleadingly suggested that intravenous administration of iodinated contrast is not a significant cause of contrast-induced nephropathy. This contrasts with previous studies and clinical observations of numerous contrast-induced nephropathy cases occurring in the setting of intravenous contrast exposure. A severe cause of contrast-induced nephropathy is presented occurring in a patient with near-normal creatinine receiving intravenous contrast only leading to dialysis and near death.

Harmful effect of repetitive intravenous iodinated contrast media administration on the long-term renal function of patients with early gastric cancer

This retrospective study investigated whether repetitive exposure to intravenous iodinated contrast media (ICM) affects long-term renal function in patients who undergo curative surgery for early gastric cancer (EGC) collected from the Korean Health Insurance and Review Assessment (HIRA) database. Patients diagnosed with gastric cancer between January 2010 and December 2013 underwent regular computed tomography (CT) scans to monitor for extragastric recurrence. Patients who already had chronic kidney disease (CKD) before cancer diagnosis or had undergone chemotherapy or repeated surgery were excluded. A nested case-control study design was chosen to analyze the effect of repetitive ICM exposure to long-term renal function by comparing patients who developed CKD 2 years after cancer diagnosis and patients who did not. Among 59,971 patients collected according to inclusion and exclusion criteria, 1021 were diagnosed with CKD 2 years after cancer diagnosis. Using 1:5 matching after adjusting for age, sex and date of cancer diagnosis, 5097 control patients were matched to 1021 CKD patients. Conditional logistic regression showed that the number of CTs taken using ICM slightly increased the odds of CKD (odds ratio, 1.080; 95% confidence interval (CI): 1.059, 1.100; P < 0.0001). Thus, the administration of ICM might contribute to chronic renal function impairment.

The Number and Size of Individual Kidney Medullary Pyramids is Associated with Clinical Characteristics, Kidney Biopsy Findings, and CKD Outcomes among Kidney Donors

SIGNIFICANCE STATEMENT

Segmentation of multiple structures in cross-sectional imaging is time-consuming and impractical to perform manually, especially if the end goal is clinical implementation. In this study, we developed, validated, and demonstrated the capability of a deep learning algorithm to segment individual medullary pyramids in a rapid, accurate, and reproducible manner. The results demonstrate that cortex volume, medullary volume, number of pyramids, and mean pyramid volume is associated with patient clinical characteristics and microstructural findings and provide insights into the mechanisms that may lead to CKD.

BACKGROUND

The kidney is a lobulated organ, but little is known regarding the clinical importance of the number and size of individual kidney lobes.

METHODS

After applying a previously validated algorithm to segment the cortex and medulla, a deep-learning algorithm was developed and validated to segment and count individual medullary pyramids on contrast-enhanced computed tomography images of living kidney donors before donation. The association of cortex volume, medullary volume, number of pyramids, and mean pyramid volume with concurrent clinical characteristics (kidney function and CKD risk factors), kidney biopsy morphology (nephron number, glomerular volume, and nephrosclerosis), and short- and long-term GFR <60 or <45 ml/min per 1.73 m 2 was assessed.

RESULTS

Among 2876 living kidney donors, 1132 had short-term follow-up at a median of 3.8 months and 638 had long-term follow-up at a median of 10.0 years. Larger cortex volume was associated with younger age, male sex, larger body size, higher GFR, albuminuria, more nephrons, larger glomeruli, less nephrosclerosis, and lower risk of low GFR at follow-up. Larger pyramids were associated with older age, female sex, larger body size, higher GFR, more nephrons, larger glomerular volume, more nephrosclerosis, and higher risk of low GFR at follow-up. More pyramids were associated with younger age, male sex, greater height, no hypertension, higher GFR, lower uric acid, more nephrons, less nephrosclerosis, and a lower risk of low GFR at follow-up.

CONCLUSIONS

Cortex volume and medullary pyramid volume and count reflect underlying variation in nephron number and nephron size as well as merging of pyramids because of age-related nephrosclerosis, with loss of detectable cortical columns separating pyramids.

Key Considerations regarding the Renal Risks of Iodinated Contrast Media: The Nephrologist's Role

BACKGROUND

The administration of iodinated contrast medium during diagnostic and therapeutic procedures has always been associated with the fear of causing acute kidney injury (AKI) or an exacerbation of chronic kidney disease. This has led, on the one hand, to the deterrence, when possible, of the use of contrast medium (preferring other imaging methods with the risk of loss of diagnostic power), and on the other hand, to the trialling of multiple prophylaxis protocols in an attempt to reduce the risk of kidney injury.

SUMMARY

A literature review on contrast-induced (CI)-AKI risk mitigation strategies was performed, focussing on the recognition of individual risk factors and on the most recent evidence regarding prophylaxis.

KEY MESSAGES

Nephrologists can contribute significantly in the CI-AKI context, from the early stages of the decision-making process to stratifying patients by risk, individualising prophylaxis measures based on the risk profile, and ensuring appropriate evaluation of kidney function and damage post-procedure to improve care.

Electronic alert outpatient protocol improves the quality of care for the risk of postcontrast acute kidney injury following computed tomography

BACKGROUND

Prevention and diagnosis of postcontrast acute kidney injury (AKI) after contrast-enhanced computed tomography is burdensome in outpatient department. We investigated whether an electronic alert system could improve prevention and diagnosis of postcontrast AKI.

METHODS

In March 2018, we launched an electronic alert system that automatically identifies patients with a baseline estimated glomerular filtration rate of <45 mL/min/1.73 m2, provides a prescription of fluid regimen, and recommends a follow-up for serum creatinine measurement. Participants prescribed contrast-enhanced computed tomography at outpatient department before and after the launch of the system were categorized as historical and alert group, respectively. Propensity for the surveillance of postcontrast AKI was compared using logistic regression. Risks of AKI, admission, mortality, and renal replacement therapy were analyzed.

RESULTS

The historical and alert groups included 289 and 309 participants, respectively. The alert group was more likely to be men and take diuretics. The most frequent volume of prophylactic fluid in historical and alert group was 1,000 and 750 mL, respectively. Follow-up for AKI was more common in the alert group (adjusted odds ratio, 6.00; p < 0.001). Among them, incidence of postcontrast AKI was not statistically different. The two groups did not differ in risks of admission, mortality, or renal replacement therapy.

CONCLUSION

The electronic alert system could assist in the detection of high-risk patients, prevention with reduced fluid volume, and proper diagnosis of postcontrast AKI, while limiting the prescribing clinicians' burden. Whether the system can improve long-term outcomes remains unclear.

Image quality of spectral brain computed tomography angiography using halved dose of iodine contrast medium

PURPOSE

Reduction in iodinated contrast medium (CM) dose is highly motivated. Our aim was to evaluate if a 50% reduction of CM, while preserving image quality, is possible in brain CT angiography (CTA) using virtual monoenergetic images (VMI) on spectral CT. As a secondary aim, we evaluated if VMI can salvage examinations with suboptimal CM timing.

METHODS

Consecutive patients older than 18 years without intracranial stenosis/occlusion were included. Three imaging protocols were used: group 1, full CM dose; group 2, 50% CM dose suboptimal timing; and group 3, 50% CM dose optimized timing. Attenuation, noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were measured in the internal carotid artery, M2 segment of the middle cerebral artery, and white matter for conventional images (CI) and VMI (40-200 keV). Qualitative image quality for CI and VMI (50 and 60 keV) was rated by 4 experienced reviewers.

RESULTS

Qualitatively and quantitatively, VMI (40-60 keV) improved image quality within each group. Significantly higher attenuation and CNR was found for group 3 VMI 40-50 keV, with unchanged SNR, compared to group 1 CI. Group 3 VMI 50 keV also received significantly higher rating scores than group 1 CI. Group 2 VMI (40-50 keV) had significantly higher CNR compared to group 3 CI, but the subjective image quality was similar.

CONCLUSION

VMI of 50 keV with 50% CM dose increases qualitative and quantitative image quality over CI with full CM dose. Using VMI reduces non-diagnostic examinations and may salvage CTA examinations deemed non-diagnostic due to suboptimal timing.

Role of Intravascular Ultrasound in Pulmonary Embolism Patients Undergoing Mechanical Thrombectomy: A Systematic Review

BACKGROUND

Traditionally, mechanical thrombectomy performed for pulmonary embolism (PE) necessitates the utilization of iodinated contrast. Intravascular ultrasound (IVUS) has been used as a diagnostic and therapeutic modality in the management of acute high and intermediate-risk PE. Recently, with the shortage of contrast supplies and the considerable incidence of contrast-induced acute kidney injury (CI-AKI), other safer and more feasible IVUS methods have become desirable. The purpose of this systematic review was to evaluate the importance of IVUS in patients with PE undergoing thrombectomy.

METHODS

Medline/PubMed, Embase, Scopus, and Google Scholar were searched for review studies, case reports, and case series. Clinical characteristics, outcomes and the usage of IVUS-guided mechanical thrombectomy during the treatment of acute high and intermediate-risk PE were examined in a descriptive analysis.

RESULTS

In this systematic review, we included one prospective study, two case series, and two case reports from July 2019 to May 2023. A total of 39 patients were evaluated; most were female (53.8%). The main presenting symptoms were dyspnea and chest pain (79.5%); three patients (7.9%) presented with syncope, one with shock and one with cardiac arrest. Biomarkers (troponin and BNP) were elevated in 94.6% of patients. Most patients (87.2%) had intermediate-risk PE, and 12.8% had high-risk PE. All patients presented with right-heart strain (RV/LV ratio ≥ 0.9, n = 39). Most patients (56.4%) had bilateral PE. Mechanical thrombectomy was performed using IVUS without contrast utilization in 39.4% of the patients. After the initial learning curve, contrast usage decreased gradually over time. There was a significant decrease in the composite mean arterial pressure immediately following IVUS-guided thrombectomy from 35.1 ± 7.2 to 25.2 ± 8.3 mmHg (p < 0.001). Post-procedure, there was no reported (0%) CI-AKI, no all-cause mortality, no major bleeding, or other adverse events. There was a significant improvement in symptoms and RV function at the mean follow-up.

CONCLUSIONS

New evidence suggests that IVUS-guided mechanical thrombectomy is safe, with visualization of the thrombus for optimal intervention, and reduces contrast exposure.

Carbon dioxide angiography during peripheral vascular interventions is associated with decreased cardiac and renal complications in patients with chronic kidney disease

OBJECTIVE

Patients with chronic kidney disease (CKD) who undergo peripheral vascular interventions (PVI) with iodinated contrast are at higher risk of post-contrast acute kidney injury (PC-AKI). Carbon dioxide (CO2) angiography can reduce iodinated contrast volume usage in this patient population, but its impact on PC-AKI has not been studied. We hypothesize that CO2 angiography is associated with a decrease in PC-AKI in patients with advanced CKD.

METHODS

The Vascular Quality Initiative PVI dataset from 2010 to 2021 was reviewed. Only patients with advanced CKD (estimated glomular filtration rate <45 ml/min/1.73 m2) treated for peripheral arterial disease were included. Propensity matching and multivariate logistic regression based on demographics, comorbidities, CKD stage, and indications were used to compare the outcomes of patients treated with and without CO2.

RESULTS

There were 20,706 PVIs performed in patients with advanced CKD, and only 22% utilized CO2 angiography. Compared with patients treated without CO2, patients who underwent CO2 angiography were younger and less likely to be women or White, and more likely to have poor renal function, diabetes, cardiac comorbidities, and present with tissue loss. Propensity matching yielded well-matched groups with 4472 patients in each group. The procedural details after matching demonstrated 50% reduction in the volume of contrast used (32±33 vs 65±48 mL; P < .01). PVI with CO2 angiography was associated with lower rates of PC-AKI (3.9% vs 4.8%; P = .03) and cardiac complications (2.1% vs 2.9%; P = .03) without a significant difference in technical failure or major/minor amputations. Low contrast volumes (≤50 mL for CKD3, ≤20 mL for CKD4, and ≤9 mL for CKD5) are associated with reduced risk of PC-AKI (hazard ratio, 0.59; P < .01).

CONCLUSIONS

CO2 angiography reduces iodinated contrast volume usage during PVI and is associated with decreased cardiac complications and PC-AKI. CO2 angiography is underutilized and should be considered for patients with advanced CKD who require endovascular therapy.

Recent Advances in Urinary Peptide and Proteomic Biomarkers in Chronic Kidney Disease: A Systematic Review

Biomarker development, improvement, and clinical implementation in the context of kidney disease have been a central focus of biomedical research for decades. To this point, only serum creatinine and urinary albumin excretion are well-accepted biomarkers in kidney disease. With their known blind spot in the early stages of kidney impairment and their diagnostic limitations, there is a need for better and more specific biomarkers. With the rise in large-scale analyses of the thousands of peptides in serum or urine samples using mass spectrometry techniques, hopes for biomarker development are high. Advances in proteomic research have led to the discovery of an increasing amount of potential proteomic biomarkers and the identification of candidate biomarkers for clinical implementation in the context of kidney disease management. In this review that strictly follows the PRISMA guidelines, we focus on urinary peptide and especially peptidomic biomarkers emerging from recent research and underline the role of those with the highest potential for clinical implementation. The Web of Science database (all databases) was searched on 17 October 2022, using the search terms "marker *" OR biomarker * AND "renal disease" OR "kidney disease" AND "proteome *" OR "peptid *" AND "urin *". English, full-text, original articles on humans published within the last 5 years were included, which had been cited at least five times per year. Studies based on animal models, renal transplant studies, metabolite studies, studies on miRNA, and studies on exosomal vesicles were excluded, focusing on urinary peptide biomarkers. The described search led to the identification of 3668 articles and the application of inclusion and exclusion criteria, as well as abstract and consecutive full-text analyses of three independent authors to reach a final number of 62 studies for this manuscript. The 62 manuscripts encompassed eight established single peptide biomarkers and several proteomic classifiers, including CKD273 and IgAN237. This review provides a summary of the recent evidence on single peptide urinary biomarkers in CKD, while emphasizing the increasing role of proteomic biomarker research with new research on established and new proteomic biomarkers. Lessons learned from the last 5 years in this review might encourage future studies, hopefully resulting in the routine clinical applicability of new biomarkers.

What you need to know about: imaging in patients with renal failure

Contrast-enhanced medical imaging is commonly requested in clinical practice. Contrast media provide better differentiation of tissue enhancement, improves the soft tissue contrast resolution, and enhances the ability to study the physiology and function of the organs and/or systems. However, contrast media may cause complications, especially in patients with renal failure. This article discusses the use of contrast media in common imaging modalities and the relationship between contrast media and renal function. Administration of iodinated contrast media in computed tomography may cause contrast-associated acute kidney injury; the risk factors and preventive strategies for this are elaborated in this article. Administration of gadolinium-based contrast media in magnetic resonance imaging may lead to nephrogenic systemic fibrosis. Therefore, precautions should be taken when planning for medical imaging for patients with pre-existing acute kidney injury or end-stage chronic kidney disease, for whom contrast media administration in computed tomography or magnetic resonance imaging may be relatively contraindicated. Alternatively, ultrasound contrast agents can be safely used in patients with acute kidney injury or chronic kidney disease. Clinical teams should discuss these patients with radiologists, taking into account the risk-benefits of contrast media, to determine the optimal imaging protocol or modality to answer the clinical query.

Quantitative assessment of renal functions using 68Ga-EDTA dynamic PET imaging in renal injury in mice of different origins

Background

Early detection of kidney diseases can be challenging as conventional methods such as blood tests or imaging techniques (computed tomography (CT), magnetic resonance imaging (MRI), or ultrasonography) may be insufficient to assess renal function. A single-photon emission CT (SPECT) renal scan provides a means of measuring glomerular filtration rates (GFRs), but its diagnostic accuracy is limited due to its planar imaging modality and semi-quantification property. In this study, we aimed to improve the accuracy of GFR measurement by preparing a positron emission tonometry (PET) tracer 68Ga-Ethylenediaminetetraacetic acid (68Ga-EDTA) and comprehensively evaluating its performance in healthy mice and murine models of renal dysfunction.

Methods

Dynamic PET scans were performed in healthy C57BL/6 mice and in models of renal injury, including acute kidney injury (AKI) and unilateral ureter obstruction (UUO) using 68Ga-EDTA. In a 30-min dynamic scan, PET images and time-activity curves (TACs) were acquired. Renal function and GFR values were measured using renograms and validated through serum renal function parameters, biodistribution results, and pathological staining.

Results

68Ga-EDTA dynamic PET imaging quantitatively captured the tracer elimination process. The calculated GFR values were 0.25 ± 0.02 ml/min in healthy mice, 0.01 ± 0.00 ml/min in AKI mice, and 0.25 ± 0.04, 0.29 ± 0.03 and 0.24 ± 0.01 ml/min in UUO mice, respectively. Furthermore, 68Ga-EDTA dynamic PET imaging and GFRPET were able to differentiate mild renal impairment before serum parameters indicated any changes.

Conclusions

Our findings demonstrate that 68Ga-EDTA dynamic PET provides a reliable and precise means of evaluating renal function in two murine models of renal injury. These results hold promise for the widespread clinical application of 68Ga-EDTA dynamic PET in the near future.

Development and validation of a deep neural network-based model to predict acute kidney injury following intravenous administration of iodinated contrast media in hospitalized patients with chronic kidney disease: a multicohort analysis

BACKGROUND

Stratification of chronic kidney disease (CKD) patients [estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2] at risk for post-contrast acute kidney injury (PC-AKI) following intravenous administration of iodinated contrast media (ICM) is important for clinical decision-making and clinical trial enrollment.

METHODS

The derivation and internal validation cohorts originated from the Second Xiangya Hospital. The external validation cohort was generated from the Xiangya Hospital and the openly accessible database Medical Information Mart for Intensive CareIV. PC-AKI was defined based on the serum creatinine criteria of the Kidney Disease: Improving Global Outcomes (KDIGO). Six feature selection methods were used to identify the most influential predictors from 79 candidate variables. Deep neural networks (DNNs) were used to establish the model and compared with logistic regression analyses. Model discrimination was evaluated by area under the receiver operating characteristic curve (AUC). Low-risk and high-risk cutoff points were set to stratify patients.

RESULTS

Among 4218 encounters studied, PC-AKI occurred in 10.3, 10.4 and 11.4% of encounters in the derivation, internal and external validation cohorts, respectively. The 14 variables-based DNN model had significantly better performance than the logistic regression model with AUC being 0.939 (95% confidence interval: 0.916-0.958) and 0.940 (95% confidence interval: 0.909-0.954) in the internal and external validation cohorts, respectively, and showed promising discrimination in subgroup analyses (AUC ≥ 0.800). The observed PC-AKI risks increased significantly from the low- to intermediate- to high-risk group (<1.0 to >50%) and the accuracy of patients not developing PC-AKI was 99% in the low-risk category in both the internal and external validation cohorts.

CONCLUSIONS

A DNN model using routinely available variables can accurately discriminate the risk of PC-AKI of hospitalized CKD patients following intravenous administration of ICM.

Effect of Left Atrial Pulmonary Vein Angiography on Safety and Efficacy for High-Power, Short-Duration Pulmonary Vein Isolation in Patients with Atrial Fibrillation

Imaging of pulmonary vein (PV) anatomy by angiography before pulmonary vein isolation (PVI) for atrial fibrillation (AF) has long been standard practice in many centers. Nowadays, very accurate anatomical maps can be generated by the use of high-resolution mapping catheters, and very effective ablation lesions can be generated by the use of the high-power, short-duration (HPSD) technique. In our center, PV angiography was routinely performed before PVI. However, since there is no clear evidence for this, we refrained from performing PV angiography. This study aimed to investigate whether PV angiography is still necessary when using high-resolution mapping catheters after ablation in the high-power, short-duration (HPSD) technique. A total of 139 consecutive patients with atrial fibrillation (66.25 ± 11.68 years old, 62.39% male) undergoing radiofrequency PVI were included in the study. Ablation was performed with the HPSD technique using a fixed protocol for energy delivery of 50 watts (contact force 3-20 g). We observed no significant effect on the efficacy, efficiency and complications of the ablation procedure if pulmonary vein angiography was omitted before HPSD PVI. Thus, using our protocol, it may be useful that PV angiography is avoided, especially in young patients and those with chronic renal disease.

Use of PETRA-MRA to assess intracranial arterial stenosis: Comparison with TOF-MRA, CTA, and DSA

Background and purpose

Non-invasive and accurate assessment of intracranial arterial stenosis (ICAS) is important for the evaluation of intracranial atherosclerotic disease. This study aimed to evaluate the performance of 3D pointwise encoding time reduction magnetic resonance angiography (PETRA-MRA) and compare its performance with that of 3D time-of-flight (TOF) MRA and computed tomography angiography (CTA), using digital subtraction angiography (DSA) as the reference standard in measuring the degree of stenosis and lesion length.

Materials and methods

This single-center, prospective study included a total of 52 patients (mean age 57 ± 11 years, 27 men, 25 women) with 90 intracranial arterial stenoses who underwent PETRA-MRA, TOF-MRA, CTA, and DSA within 1 month. The degree of stenosis and lesion length were measured independently by two radiologists on these four datasets. The degree of stenosis was classified according to DSA measurement. Severe stenosis was defined as a single lesion with >70% diameter stenosis. The smaller artery stenosis referred to the stenosis, which occurred at the anterior cerebral artery, middle cerebral artery, and posterior cerebral artery, except for the first segment of them. The continuous variables were compared using paired t-test or Wilcoxon signed rank test. The intraclass correlation coefficients (ICCs) were used to assess the agreement between MRAs/CTA and DSA as well as inter-reader variabilities. The ICC value >0.80 indicated excellent agreement. The agreement of data was assessed further by Bland-Altman analysis and Spearman's correlation coefficients. When the difference between MRAs/CTA and DSA was statistically significant in the degree of stenosis, the measurement of MRAs/CTA was larger than that of DSA, which referred to the overestimation of MRAs/CTA for the degree of stenosis.

Results

The four imaging methods exhibited excellent inter-reader agreement [intraclass correlation coefficients (ICCs) > 0.80]. PETRA-MRA was more consistent with DSA than with TOF-MRA and CTA in measuring the degree of stenosis (ICC = 0.94 vs. 0.79 and 0.89) and lesion length (ICC = 0.99 vs. 0.97 and 0.73). PETRA-MRA obtained the highest specificity and positive predictive value (PPV) than TOF-MRA and CTA for detecting stenosis of >50% and stenosis of >75%. TOF-MRA and CTA overestimated considerably the degree of stenosis compared with DSA (63.0% ± 15.8% and 61.0% ± 18.6% vs. 54.0% ± 18.6%, P < 0.01, respectively), whereas PETRA-MRA did not overestimate (P = 0.13). The degree of stenosis acquired on PETRA-MRA was also more consistent with that on DSA than with that on TOF-MRA and CTA in severe stenosis (ICC = 0.78 vs. 0.30 and 0.57) and smaller artery stenosis (ICC = 0.95 vs. 0.70 and 0.80). In anterior artery circulation stenosis, PETRA-MRA also achieved a little bigger ICC than TOF-MRA and CTA in measuring the degree of stenosis (0.93 vs. 0.78 and 0.88). In posterior artery circulation stenosis, PETRA-MRA had a bigger ICC than TOF-MRA (0.94 vs. 0.71) and a comparable ICC to CTA (0.94 vs. 0.91) in measuring the degree of stenosis.

Conclusion

PETRA-MRA is more accurate than TOF-MRA and CTA for the evaluation of intracranial stenosis and lesion length when using DSA as a reference standard. PETRA-MRA is a promising non-invasive tool for ICAS assessment.

Application of CT contrast medium is not associated with an increased risk for acute kidney injury in patients with decompensated cirrhosis

BACKGROUND

Acute kidney injury (AKI) is a frequent complication in patients with decompensated cirrhosis. Studies reported conflicting results regarding the nephrotoxic potential of iodinated contrast medium (CM) for computer tomography (CT).

AIM

To investigate the impact of diagnostic CM application on kidney function in patients with decompensated cirrhosis.

METHODS

First, we evaluated the impact of diagnostic CM-CT on AKI incidence in a cross-sectional approach. Second, we analysed 28-day AKI incidence post-CM-CT in patients with impaired kidney function (i.e., creatinine >133 μmoL/L). Third, we excluded all patients with relevant interventions besides CM-CT. All remaining patients were matched via propensity score matching (PPSM) and further analysed. Last, we validated the results in an independent dataset of prospectively collected registry data of 118 patients with decompensated cirrhosis. Here, plasma samples were analysed regarding neutrophil-gelatinase-associated-lipocalin (NGAL).

RESULTS

Of the 611 included patients, 98 (16%) received CM-CT. CM-CT was not associated with AKI in the cross-sectional approach (CM-CT:8% vs. no CM-CT:15%; p = 0.08). Furthermore, CM-CT was not associated with higher 28-day AKI incidence among patients with impaired kidney function (HR:0.79; 95% CI 0.45-1.38; p = 0.40). The PPSM cohort revealed no association between CM-CT and AKI or severe AKI (HR:1.28, p = 0.45 and HR:1.62; p = 0.43). Moreover, CM-CT did not result in worsening of kidney function after CM application. In the validation cohort, CM-CT was also not linked to AKI (p = 0.85) and NGAL levels were not increased in those with CM-CT (CM-CT:309 ng/ml vs. No CM-CT:266 ng/ml, p = 0.35).

CONCLUSION

Decompensated cirrhosis per se should not preclude diagnostic CM-CT.

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.

Molecular mechanisms underlying the renal protective effects of coenzyme Q10 in acute kidney injury

Coenzyme Q10 (CoQ10), an endogenous antioxidant, has been reported frequently to exert an outstanding protective effect on multiple organ injury, including acute kidney injury (AKI). In this study, we aim to summarize all the current evidence of the protective action of CoQ10 against AKI as there are presently no relevant reviews in the literature. After a systematic search, 20 eligible studies, either clinical trials or experimental studies, were included and further reviewed. CoQ10 treatment exhibited a potent renal protective effect on various types of AKI, such as AKI induced by drugs (e.g., ochratoxin A, cisplatin, gentamicin, L-NAME, and nonsteroidal anti-inflammatory drug), extracorporeal shock wave lithotripsy (ESWL), sepsis, contrast media, and ischemia–reperfusion injury. The renal protective role of CoQ10 against AKI might be mediated by the antiperoxidative, anti-apoptotic, and anti-inflammatory potential of CoQ10. The molecular mechanisms for the protective effects of CoQ10 might be attributed to the regulation of multiple essential genes (e.g., caspase-3, p53, and PON1) and signaling cascades (e.g., Nrf2/HO-1 pathway). This review highlights that CoQ10 may be a potential strategy in the treatment of AKI.

[The atorvastatin effects on the prevention of contrast-induced acute kidney injury during computed tomography with contrast media]

AIM

To assess the role of atorvastatin to the frequency of contrast-induced acute kidney injury (CI-AKI) in patients with cardiovascular diseases (CVD) undergoing computed tomography (CT) with intravenous contrast media.

MATERIALS AND METHODS

One hundred patients with CVD undergoing CT with with intravenous contrast media administration were included in prospective observational study (ClinicalTrials.gov ID NCT04666389). Patients were divided into 3 groups 16 (15.8%) patients receiving atorvastatin at a dose of 80 mg 24 hours and 40 mg before the CT and 40 mg after; 33 (32.7%) patients 40 mg before the CT and 40 mg after; 52 (51.5%) people not receiving statin therapy. The primary endpoint was CI-AKI according to KDIGO criteria: the 25% rise (or 0.5 mg/dl) of serum creatinine from baseline assessed 4872 hours after administration of contrast media. There were 51% of men. The average age was 59.7714.4. The most frequent cardiovascular disease was hypertension 86%.

RESULTS

CI-AKI was diagnosed in 4 (3.96%) patients. At the same time, it was not possible to establish statistically significant relationships (p0.05) between risk factors and the development of CI-AKI. Statins can be a successful way to prevent this complication.

CONCLUSION

Cardiovascular diseases may increase the risk of CI-AKI after computed tomography with intravenous contrast media administration. Therefore, it is recommended to evaluate the serum creatinine concentration in such patients.

Contrast Media Reduction in Computed Tomography With Deep Learning Using a Generative Adversarial Network in an Experimental Animal Study

OBJECTIVE

This feasibility study aimed to use optimized virtual contrast enhancement through generative adversarial networks (GAN) to reduce the dose of iodine-based contrast medium (CM) during abdominal computed tomography (CT) in a large animal model.

METHODS

Multiphasic abdominal low-kilovolt CTs (90 kV) with low (low CM, 105 mgl/kg) and normal contrast media doses (normal CM, 350 mgl/kg) were performed with 20 healthy Göttingen minipigs on 3 separate occasions for a total of 120 examinations. These included an early arterial, late arterial, portal venous, and venous contrast phase. One animal had to be excluded because of incomplete examinations. Three of the 19 animals were randomly selected and withheld for validation (18 studies). Subsequently, the GAN was trained for image-to-image conversion from low CM to normal CM (virtual CM) with the remaining 16 animals (96 examinations). For validation, region of interest measurements were performed in the abdominal aorta, inferior vena cava, portal vein, liver parenchyma, and autochthonous back muscles, and the contrast-to-noise ratio (CNR) was calculated. In addition, the normal CM and virtual CM data were presented in a visual Turing test to 3 radiology consultants. On the one hand, they had to decide which images were derived from the normal CM examination. On the other hand, they had to evaluate whether both images are pathological consistent.

RESULTS

Average vascular CNR (low CM 6.9 ± 7.0 vs virtual CM 28.7 ± 23.8, P < 0.0001) and parenchymal (low CM 1.5 ± 0.7 vs virtual CM 3.8 ± 2.0, P < 0.0001) CNR increased significantly by GAN-based contrast enhancement in all contrast phases and was not significantly different from normal CM examinations (vascular: virtual CM 28.7 ± 23.8 vs normal CM 34.2 ± 28.8; parenchymal: virtual CM 3.8 ± 2.0 vs normal CM 3.7 ± 2.6). During the visual Turing testing, the radiology consultants reported that images from normal CM and virtual CM were pathologically consistent in median in 96.5% of the examinations. Furthermore, it was possible for the examiners to identify the normal CM data as such in median in 91% of the cases.

CONCLUSIONS

In this feasibility study, it could be demonstrated in an experimental setting with healthy Göttingen minipigs that the amount of CM for abdominal CT can be reduced by approximately 70% by GAN-based contrast enhancement with satisfactory image quality.

Contrast-Induced Neurotoxicity: An Inside Look at a Rare Presentation

Imaging modalities frequently utilize iodinated-based contrast agents (IBCAs) to assist professionals in deficit identification and improve clinical outcomes for patients. However, they are not without risk. In patients with post-radiological neurological deficits, contrast-induced neurotoxicity (CIN) should be among the top differentials. In this case report, we present the case of a 61-year-old female who experienced classical signs and symptoms of neurotoxicity after a cerebral angiogram. The patient's clinical detriments stemming from iodinated contrast resolved after a multi-day treatment of high-dose steroid use.

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.

Factors influencing the time-intensity curve analysis of contrast-enhanced ultrasound in kidney transplanted patients: Toward a standardized contrast-enhanced ultrasound examination

Background

Time-intensity curve analysis (TIC analysis) based on contrast-enhanced ultrasound (CEUS) provides quantifiable information about the microcirculation of different tissues. TIC analysis of kidney transplantations is still a field of research, and standardized study protocols are missing though being mandatory for the interpretation of TIC parameters in the clinical context. The aim of this study was to evaluate the impact of different sizes and forms of regions of interest (ROIs) on the variance of different TIC parameters and the level of interoperator variance between the different ROI methods in kidney transplantations.

Methods

In 25 renal transplanted patients, 33 CEUS of the transplanted kidney were performed, and TIC analysis with ROIs sized 5 mm2 (ROI5), 10 mm2 (ROI10), and ROIs circumscribing the outlines of anatomical regions (ROI Anat ) were analyzed based on CEUS examination. The TIC analysis was repeated by a second independent operator for ROI5 and ROI Anat .

Results

Statistical analysis revealed significant differences between TIC parameters of different ROI methods, and overall, the interoperator variance was low. But a greater ROI surface (ROI10) led to higher values of the intensity parameters A and AUC compared with ROI5 (p < 0.05). The difference in the ROI form led to high variation of certain TIC parameters between ROI5 and ROI Anat in the myelon [intraclass correlation coefficient (A, ICC = 0.578 (0.139-0.793); TIC parameter (TTP); and ICC = 0.679 (0.344-0.842) (p < 0.05)]. A mean variation of 1 cm of the depth of ROI5 in the cortex did not show significant differences in the TIC parameters, though there was an impact of depth of ROI Anat on the values of TIC parameters. The interoperator variance in the cortex was low and equal for ROI5 and ROI Anat , but increased in the myelon, especially for ROI Anat . Furthermore, the analysis revealed a strong correlation between the parameter AUC and the time interval applied for the TIC analysis in the cortex and myelon (r = 0.710, 0.674, p < 0.000).

Conclusion

Our findings suggest the application of multiple ROIs of 5 mm2 in the cortex and medulla to perform TIC analysis of kidney transplants. For clinical interpretation of AUC, a standardized time interval for TIC analysis should be developed. After the standardization of the TIC analysis, the clinical predictive value could be investigated in further studies.

Canadian Association of Radiologists Guidance on Contrast Associated Acute Kidney Injury

Iodinated contrast media (ICM) is one of the most frequently administered pharmaceuticals. In Canada, over 5.4 million computed tomography (CT) examinations were performed in 2019, of which 50% were contrast enhanced. Acute kidney injury (AKI) occurring after ICM administration was historically considered a common iatrogenic complication which was managed by screening patients, prophylactic strategies, and follow up evaluation of renal function. The Canadian Association of Radiologists (CAR) initially published guidelines on the prevention of contrast induced nephropathy in 2007, with an update in 2012. However, new developments in the field have led to the availability of safer contrast agents and changes in clinical practice, prompting a complete revision of the earlier recommendations. This revised guidance document was developed by a multidisciplinary CAR Working Group of radiologists and nephrologists, and summarizes changes in practice related to contrast administration, screening, and risk stratification since the last guideline. It reviews the scientific evidence for contrast associated AKI and provides consensus-based recommendations for its prevention and management in the Canadian healthcare context. This article is a joint publication in the Canadian Association of Radiologists Journal and Canadian Journal of Kidney Health and Disease, intended to inform both communities of practice.

North American Practice-Based Recommendations for Transjugular Intrahepatic Portosystemic Shunts in Portal Hypertension

Complications of portal hypertension, including ascites, gastrointestinal bleeding, hepatic hydrothorax, and hepatic encephalopathy, are associated with significant morbidity and mortality. Despite few high-quality randomized controlled trials to guide therapeutic decisions, transjugular intrahepatic portosystemic shunt (TIPS) creation has emerged as a crucial therapeutic option to treat complications of portal hypertension. In North America, the decision to perform TIPS involves gastroenterologists, hepatologists, and interventional radiologists, but TIPS creation is performed by interventional radiologists. This is in contrast to other parts of the world where TIPS creation is performed primarily by hepatologists. Thus, the successful use of TIPS in North America is dependent on a multidisciplinary approach and technical expertise, so as to optimize outcomes. Recently, new procedural techniques, TIPS stent technology, and indications for TIPS have emerged. As a result, practices and outcomes vary greatly across institutions and significant knowledge gaps exist. In this consensus statement, the Advancing Liver Therapeutic Approaches group critically reviews the application of TIPS in the management of portal hypertension. Advancing Liver Therapeutic Approaches convened a multidisciplinary group of North American experts from hepatology, interventional radiology, transplant surgery, nephrology, cardiology, pulmonology, and hematology to critically review existing literature and develop practice-based recommendations for the use of TIPS in patients with any cause of portal hypertension in terms of candidate selection, procedural best practices and, post-TIPS management; and to develop areas of consensus for TIPS indications and the prevention of complications. Finally, future research directions are identified related to TIPS for the management of portal hypertension.

Risk of acute kidney injury after contrast-enhanced computerized tomography: a systematic review and meta-analysis of 21 propensity score-matched cohort studies

OBJECTIVES

Intravenous application of contrast media is part of a wide spectrum of diagnostic procedures for better imaging quality. Clinical avoidance of contrast-enhanced imaging is an ever-present quandary in patients with impaired kidney function. The objective of this study was to estimate the risk for acute kidney injury (AKI), dialysis and mortality among patients undergoing contrast-enhanced CT compared to propensity score-matched controls (i.e. contrast-unenhanced CT). Selected cohort studies featured high-risk patients with advanced kidney disease and critical illness.

METHODS

This review was designed to conform to the Preferred Reporting Items in Systematic Reviews and Meta-Analysis (PRISMA) guidelines. PubMed was searched from August 2021 to November 2021 for all-language articles without date restriction. A random-effects model (DerSimonian and Laird method) was used for meta-analysis.

RESULTS

Twenty-one articles were included, comprising data of 169,455 patients. The overall risk of AKI was similar in the contrast-enhanced and unenhanced groups (OR: 0.97 [95% CI: 0.85; 1.11], p = 0.64), regardless of baseline renal function and underlying disease. Substantial heterogeneity was detected (I² = 90%, p ≤ 0.0001). Multivariable logistic regression identified hypertension (p = 0.03) and estimated glomerular filtration rate (eGFR) ≤ 30 mL/min/1.73 m² (p = 0.0001) as factors associated with greater risk of post-contrast AKI.

CONCLUSIONS

Based on propensity score-matched pairs obtained from 21 cohort studies, we found no evidence for increased risk for AKI, dialysis or mortality after contrast-enhanced CT among patients with eGFR ≥ 45 mL/min/1.73 m². In congruence with the emerging evidence in the literature, caution should be exercised in patients with hypertension and eGFR ≤ 30 mL/min/1.73 m².

KEY POINTS

• The application of contrast media for medical imaging is not associated with higher odds for AKI, induction of renal replacement therapy, or mortality. Many comorbidities traditionally associated with greater risk for acute kidney injury do not appear to predispose for renal decline after contrast media exposure. • Underlying hypertension and eGFR less than or equal to 30 mL/min/1.73 m² seem to predispose for post-contrast acute kidney injury. • Propensity score matching cannot account for unmeasured influences on AKI incidence, which needs to be addressed in the interpretation of results.

Does intravenous contrast medium administration result in altered renal biomarkers? A study in clinically stable cats with and without azotemia

OBJECTIVES

The aim of this study was to determine the prevalence of post-contrast acute kidney injury or comparable side effects on kidney function in cats receiving the non-ionic, iodinated agent ioversol and/or paramagnetic agent gadoteric acid.

METHODS

Fifty-two animals were divided into four groups on the basis of contrast medium administration for imaging: ioversol (n = 27), gadoteric acid (n = 12), dual contrast media (n = 4) or control, which received an infusion of isotone intravenous fluids only during anaesthesia (n = 9). Blood and urine samples were obtained three times after contrast administration and compared with values obtained prior to administration of the contrast medium. Creatinine (<1.60 mg/dl), symmetric dimethylarginine (SDMA; ⩽14 μg/dl), urine protein:creatinine ratio (UPC; <0.2) and critical differences for creatinine (<0.3 mg/dl) and SDMA (<5.98 μg/dl) were measured.

RESULTS

No significant short-term effects on mean creatinine, SDMA and UPC measurements were seen. Borderline proteinuria (UPC, 0.2-0.4) was detected in 11.4% of cases after contrast media administration. A UPC of more than 0.2 in five cases indicated that contrast media may affect kidney function, leading to (transient) proteinuria.

CONCLUSIONS AND RELEVANCE

This study found no side effect on renal function following the administration of ioversol or gadoteric acid, provided patients were adequately hydrated. However, the clinical relevance of proteinuria in some cats needs to be evaluated in future studies.

Canadian Association of Radiologists Guidance on Contrast-Associated Acute Kidney Injury

Purpose

Iodinated contrast media is one of the most frequently administered pharmaceuticals. In Canada, over 5.4 million computed tomography (CT) examinations were performed in 2019, of which 50% were contrast enhanced. Acute kidney injury (AKI) occurring after iodinated contrast administration was historically considered a common iatrogenic complication which was managed by screening patients, prophylactic strategies, and follow-up evaluation of renal function. The Canadian Association of Radiologists (CAR) initially published guidelines on the prevention of contrast induced nephropathy in 2007, with an update in 2012. However, new developments in the field have led to the availability of safer contrast agents and changes in clinical practice, prompting a complete revision of the earlier recommendations.

Information sources

Published literature, including clinical trials, retrospective cohort series, review articles, and case reports, along with expert opinions from radiologists and nephrologists across Canada.

Methods

The leadership of the CAR formed a working group of radiologists and nephrologists with expertise in contrast administration and patient management related to contrast-associated AKI. We conducted a comprehensive review of the published literature to evaluate the evidence about contrast as a cause of AKI, and to inform evidence-based recommendations. Based on the available literature, the working group developed consensus recommendations.

Key Findings

The working group developed 21 recommendations, on screening, choice of iodinated contrast media, prophylaxis, medication considerations, and post contrast administration management. The key changes from the 2012 guidelines were (1) Simplification of screening to a simple questionnaire, and not delaying emergent examinations due to a need for creatinine measurements (2) Prophylaxis considerations only for patients with estimated glomerular filtration rate (eGFR) less than 30 mL/min/1.73 m2 (3) Not recommending the routine discontinuation of any drugs to decrease risk of AKI, except metformin when eGFR is less than 30 mL/min/1.73 m2 and (4) Not requiring routine follow up serum creatinine measurements post iodinated contrast administration.

Limitations

We did not conduct a formal systematic review or meta-analysis. We did not evaluate our specific suggestions in the clinical environment.

Implications

Given the importance of iodinated contrast media use in diagnosis and management, and the low risk of AKI after contrast use, these guidelines aim to streamline the processes around iodinated contrast use in most clinical settings. As newer evidence arises that may change or add to the recommendations provided, the working group will revise these guidelines.

The removal of race from kidney function estimation: Key points for primary providers

Recent recognitions of longstanding societal effects of structural and overt acts of racism have led to calls for the elimination of race, a social construct, from medical algorithms. This accelerated a growing concern with the use of race in kidney function estimating equations. A task force sponsored by the two leading nephrology societies in the United States has reassessed the inclusion of race in glomerular filtration rate (GFR) estimation and recently put forth recommendations. New race-free equations have been developed and guides for widespread implementation have been provided. We herein review the journey of kidney function estimating equations, race in GFR estimating equations, new race-free equations and the path forward in caring for chronic kidney disease. We urge upon all primary care providers to employ concerted focus on early detection and identification of kidney dysfunction as well as risk factors including social determinants of health to prevent progression.

The Development of Acute Kidney Injury in Burn Patients Undergoing Computed Tomography With Intravenous Contrast

Acute kidney injury (AKI) is a major complication of significant burn injuries and a significant cause of patient morbidity and mortality. Patients that sustain traumatic burn injuries may require computed tomography (CT) imaging as part of their initial trauma management. This multicenter retrospective chart review of patients admitted to two level I trauma centers with ≥10% TBSA burns between 2014 and 2017 aims to determine if patients with greater than 10% TBSA burns that received CT imaging with intravenous contrast were more likely to develop acute kidney injury during their admission. A total of 439 patients were included in the study. The average age was 45.3 years and average TBSA was 23.2%. Sixty-seven of the 439 patients underwent CT scans with IV contrast on admission. The rate of AKI between patients who did or did not receive CT scans was not statistically significant (9.1 vs 6.0%, P = 0.40). Patients who developed an AKI had higher TBSA (45.6 vs 21.1%, P < .01), amount of fluids per TBSA given within the first 24 hours (457.4 vs 321.6, P < .01), and mortality (71.1 vs 6.2%, P < .01) than those who did not develop an AKI. There was no significant difference in the development of acute kidney injury in burn patients who received CT scans with IV contrast on admission. Although there is a risk of contrast induced nephropathy, the risk is not increased in burn patients and this should not prevent a thorough evaluation to rule out additional life-threatening injuries in the burn trauma patient.

Artificial Intelligence Algorithm-Based Computed Tomography Image in Assessment of Acute Renal Insufficiency of Patients Undergoing Percutaneous Coronary Intervention

This study was aimed to analyze the changes in renal function of patients undergoing percutaneous coronary intervention (PCI) surgery and the characteristics of their computed tomography (CT) image based on artificial intelligence algorithms. In this study, 104 patients with coronary atherosclerotic heart disease (CAHD) were treated as the research objects. They were divided into an experimental group (patients who underwent CAG and PCI within 1 week after enhanced coronary CT (ECCT)) and the control group (patients who underwent CAG and PCI within 1-3 weeks after ECCT). Renal imaging scans of patients were performed by CT based on discrete inseparable shear transform (DNST) optimized algorithm, which was named as O-DNST. The results showed that the serum creatinine (Scr), blood urea nitrogen (BUN), and urine protein (UP) levels of patients in the experimental group were significantly higher than those of the control group 24-72 hours after surgery, while the levels of endogenous creatinine clearance (Ccr) and estimated glomerular filtration rate (eGFR) were significantly lower than those of the control group (P < 0.05). The levels of β2 microglobulin (β2-MG), C-reactive protein (CRP), interleukin 6 (IL-6), and tumor necrosis factor (TNF-α) in the experimental group were significantly higher than those in the control group 24-72 hours after surgery (P < 0.05). The incidence of contrast-induced nephropathy (CIN) in the experimental group (15.38%) was significantly higher than that in the control group (5.8%), and the difference was statistically significant (P < 0.05). The results showed that repeated application of contrast agent in a short period of time can promote the increase of serum inflammation levels in PCI patients, which may be a risk factor for CIN in PCI patients.