Prophylaxis of contrast-induced nephrotoxicity

Impact of iodine contrast media on gamma camera-based GFR and factors affecting the difference between serum creatinine-based estimated GFR and Gate's GFR

OBJECTIVE

We aimed to elucidate the factors underlying the difference between estimated glomerular filtration rate (eGFR) calculated from serum creatinine and Gate's GFR (gGFR) measured using technetium-99m diethylene triamine pentaacetic acid ( 99m Tc-DTPA) scintigraphy.

METHODS

This study was based on consecutive patients who underwent 99m Tc-DTPA scintigraphy at our hospital between January 2021 and December 2022 and whose blood serum creatinine data were obtained on the same day as the 99m Tc-DTPA scintigraphy. Relationships between the ratio of gGFR and eGFR (gGFR/eGFR) and age, sex, BMI, visceral fat, psoas muscle index (PMI), serum blood urea nitrogen, and creatinine level were investigated based on 75 patients. Additionally, for 44 patients who had two or more follow-up DTPA studies, we compared gGFR values for studies that used iodine contrast media (ICM) for computed tomography before same-day 99m Tc-DTPA studies and those that did not in the same patients.

RESULTS

Weak correlations were observed between gGFR/eGFR and PMI ( r  = 0.30), BMI ( r  = 0.24), and the visceral fat area ( r  = 0.33). Multi-regression analyses showed that gGFR/eGFR was correlated with PMI ( β  = 0.34, P  < 0.01) and approached significance with the visceral fat area ( β  = 0.24, P  = 0.05). A significant difference was observed in gGFR between patients who received ICM before the 99m Tc-DTPA renogram and those who did not ( P  < 0.001, eGFR 80.5 ± 19.0 vs. 91.7 ± 27.8 ml/min).

CONCLUSION

ICM administration temporarily decreased gGFR, and increased muscle mass increased the difference between eGFR and gGFR values.

Customised weight-based volume contrast media protocol for multiphase abdominal computed tomography

INTRODUCTION

Multiphase computed tomography (CT) using fixed volume contrast media may lead to high radiation exposure and toxicity in patients with low body weight. We evaluated a customised weight-based protocol for multiphase CT in terms of radiation exposure, image quality and cost savings.

METHODS

A total of 224 patients were recruited. An optimised CT protocol was applied using 100 kV and 1 mL/kg of contrast media dosing. The image quality and radiation dose exposure of this CT protocol were compared to those of a standard 120 kV, 80 mL fixed volume protocol. The radiation dose information and CT Hounsfield units were recorded. The signal-to-noise ratio, contrast-to-noise ratio (CNR) and figure of merit (FOM) were used as comparison metrics. The images were assessed for contrast opacification and visual quality by two radiologists. The renal function, contrast media volume and cost were also evaluated.

RESULTS

The median effective dose was lowered by 16% in the optimised protocol, while the arterial phase images achieved significantly higher CNR and FOM. The radiologists' evaluation showed more than 97% absolute agreement with no significant differences in image quality. No significant differences were found in the pre- and post-CT estimated glomerular filtration rate. However, contrast media usage was significantly reduced by 1,680 mL, with an overall cost savings of USD 421 in the optimised protocol.

CONCLUSION

The optimised weight-based protocol is cost-efficient and lowers radiation dose while maintaining overall contrast enhancement and image quality.

Effectiveness of N-Acetylcysteine in the Treatment of Renal Deterioration Caused by Long-Term Exposure to Bisphenol A

Human health hazards caused by bisphenol A (BPA), a precursor for epoxy resins and polycarbonate-based plastics, are well documented and are closely associated with mitochondrial impairment and oxidative imbalance. This study aimed to assess the therapeutic efficacy of N-acetylcysteine (NAC) on renal deterioration caused by long-term BPA exposure and examine the signaling transduction pathway involved. Male Wistar rats were given vehicle or BPA orally for 12 weeks then the BPA-treated group was subdivided to receive vehicle or NAC concurrently with BPA for a further 4 weeks, while the vehicle-treated normal control group continued to receive vehicle through to the end of experiment. Proteinuria, azotemia, glomerular filtration reduction and histopathological abnormalities caused by chronic BPA exposure were significantly reduced following NAC therapy. NAC also diminished nitric oxide and lipid peroxidation but enhanced renal glutathione levels, and counteracted BPA-induced mitochondrial swelling, increased mitochondrial reactive oxygen species production, and the loss of mitochondrial membrane potential. The benefit of NAC was related to the modulation of signaling proteins in the AMPK-SIRT3-SOD2 axis. The present study shows the potential of NAC to restore mitochondrial integrity and oxidative balance after long-term BPA exposure, and suggests that NAC therapy is an effective approach to tackle renal deterioration in this condition.

Circulating Exosomal miR-1-3p from Rats with Myocardial Infarction Plays a Protective Effect on Contrast-Induced Nephropathy via Targeting ATG13 and activating the AKT Signaling Pathway

Rationale: With the widespread development of the interventional technique for cardiovascular diseases and the widespread use of contrast medium (CM), the incidence of contrast-induced nephropathy (CIN) has been increasing, which is associated with poor prognosis for cardiovascular diseases. This study aims to explore the effect of circulating exosomal microRNA from patients with myocardial infarction (MI) on CIN and related molecular mechanism. Methods: A rat MI model was established by ligating the left anterior descending coronary artery. Circulating exosomes were isolated from control (Exo-NC) and MI rats (Exo-MI) using a commercial kit. The in vivo and in vitro models of CIN were created using iodixanol. Reverse transcription quantitative PCR (RT-qPCR) was utilized to detect the expression of miR-1-3p. Western blot (WB) was used to detect the expression of exosomal surface markers, and apoptosis-related and autophagy-related proteins. The apoptosis rate was examined by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) staining and flow cytometry (FC). Transmission electron microscopy (TEM) was utilized to observe the exosomes and autophagosomes. Rat kidney injury was assessed by hematoxylin and eosin (H&E) staining and kidney injury molecule-1 (KIM-1) immunohistochemical staining. Renal function of rats was assessed by detecting the levels of blood urea nitrogen (BUN) and serum creatinine (Cr). The dual luciferase reporter assay was performed to identify the target gene of miR-1-3p. Results: The treatment of CM induced NRK-52E cell damage, which manifested as enhanced cell autophagy and enhanced apoptosis. The Exo-MI treatment significantly inhibited the CM-induced autophagy and apoptosis of NRK-52E cells. Furthermore, the Exo-MI treatment increased the Bcl-2 expression, but decreased the Bax expression and the ratio of LC3II/LC3I. Furthermore, the results of the TUNEL staining and FC showed that Exo-MI can reduce apoptotic rate. Through TEM, it was found that Exo-MI reduced the number of autophagosomes in NRK-52E cells. The rescue experiments revealed that the function of Exo-MI is to inhibit the CM-induced autophagy and apoptosis of NRK-52E cells, which can be inhibited by the miR-1-3p inhibitor. Furthermore, it was found that the overexpression of miR-1-3p can also inhibit the CM-induced autophagy and apoptosis of NRK-52E cells. Through dual luciferase reporter assay, ATG13 was found to be the target of miR-1-3p. In addition, the overexpression of miR-1-3p significantly reversed the CM-induced decrease in phosphorylation level of AKT. Furthermore, ATG13 silencing can also inhibit the CM-induced autophagy and apoptosis of NRK-52E cells. In vivo, Exo-MI significantly alleviated the renal injury, reduced the renal fibrosis, and improved the renal function of CIN rats. Conclusion: The circulating exosomal miR-1-3p after MI inhibited the CM-induced apoptosis and autophagy of renal tubular epithelial cells, and improved the renal function of rats by targeting ATG13 and activating the AKT signaling pathway.

Low contrast volume dual-energy CT of the chest: Quantitative and qualitative assessment

PURPOSE

To evaluate the image quality of chest CT performed on dual-energy scanners using low contrast volume for routine chest (DECT-R) and pulmonary angiography (DECTPA) protocols.

MATERIALS AND METHODS

This retrospective study included dual-energy CT scans of chest performed with low contrast volume in 84 adults (34M:50F; Age 69 ± 16 years: Weight 71 ± 16kg). There were 42 patients with DECT-R and 42 patients with DECT-PA protocols. Images were reviewed by two thoracic radiologists. Qualitative assessment was done on a four-point scale, for subjective assessment of contrast enhancement and artifacts (1 = Excellent, 2 = optimal, 3 = suboptimal, and 4 = Limited) in the pulmonary arteries and thoracic aorta, on virtual monoenergetic and material decomposition iodine (MDI) images. Quantitative assessment was performed by measuring the CT (Hounsfield) units in aorta and pulmonary arteries. The estimated glomerular filtration rate (eGFR) was calculated before and after CT scans. Two tailed student's t-test was performed to assess the significance of findings, and strength of correlation between readers was determined by Cohen's kappa test.

RESULTS

DECT-PA and DECT-R demonstrated excellent/adequate contrast density within the pulmonary arteries (up to segmental branch), and aorta. There was no suboptimal or limited examination. There was strong interobserver agreement for arterial enhancement in pulmonary arteries (kappa = 0.62-0.89) and for thoracic aorta (kappa = 0.62-0.94). Pulmonary emboli were seen in 3/42(7%) in DECT-R and in 5/42(12%) in DECT-PA. There was no significant change in eGFR before and after IV contrast injection (p = 0.46-0.52).

CONCLUSION

DECT-R and DECT-PA performed with low contrast volume provide diagnostic quality opacification of the pulmonary vessels and aorta vessels.

Coronary CT angiography by modifying tube voltage and contrast medium concentration: Evaluation of image quality and radiation dose

BACKGROUND

Currently, there is an increasing interest in noninvasive imaging of cardiovascular system such as computed tomography coronary angiography (CCTA). The risks of radiation-induced cancer and contrast-induced nephropathy (CIN) have always been regarded as concerns which increased demand for CCTA using reduced radiation dose and iodine intake. We aimed to evaluate the image quality and radiation dose of CCTA by modifying tube voltage and concentration of contrast media.

METHODS

The present study includes 105 patients who underwent CCTA for clinical indications. Specific inclusion and exclusion criteria in terms of patient's weight, body mass index, calcium score, and stenting were used. First group of patients scanned by 120 kV and 370 mg I/mL contrast medium, compared with second and third groups for which scanning was performed using 100 kV and 370 mg I/mL and 100 kV and 300 mg I/mL, respectively. Image quality was evaluated both subjectively and objectively. The effective dose and iodine intake were also measured.

RESULTS

Using low kV protocols led to radiation dose reduction up to 38% and applying low contrast medium concentration with consequent reduced iodine intake up to 21%. Moreover, there were significant differences in image quality of new scanning protocols.

CONCLUSION

Reduction in tube voltage with lowering of contrast medium concentration can reduce radiation dose and iodine intake with acceptable image quality.

Ischemia-Modified Albumin, Creatinine, And Paraoxonase-1 Levels in Serum of Patients Undergoing Intravenous Contrast-Enhanced Computed Tomography and Its Association with Contrast-Induced Nephropathy

BACKGROUND

Following contrast-enhanced computed tomography (CECT) contrast-induced nephropathy (CIN) may occur in patients with renal insufficiency or diabetes. Creatinine, the most common marker of CIN, may not be an accurate measure of damage and is affected by many non-renal factors. Our aim was to evaluate ischemia-modified albumin (IMA) as an early CIN marker and correlate it with paraoxonase-1 (PON-1) and creatinine before and after CECT.

METHODS

Forty-eight adult patients scheduled for intravenous CECT, regardless of indication or body region for CECT, were included in this prospective study. Venous blood samples were obtained 12-24 hours before and after contrast media (CM) administration. Ischemia-modified albumin and PON-1 were estimated using methods described by Bar-Or et al. and Dantoine et.al., respectively. Creatinine was estimated on an automated analyzer.

RESULTS

Significant differences in IMA (P < 0.001) and PON-1 (P < 0.001) levels were found between pre- and post-CECT samples, while the difference for creatinine was not significant (p = 0.073). No correlation was found between IMA and PON-1 or IMA and creatinine in either the pre- or post-CECT samples.

CONCLUSION

After CM administration patients are subjected to oxidative stress and/or ischemia, as revealed by elevated IMA and decreased PON-1 levels; however, creatinine levels, most commonly estimated to assess reduced renal function, did not reflect the condition accurately. IMA may be a sensitive marker for CIN but further studies are required to confirm its usefulness.

Efficacy and safety of a balanced salt solution versus a 0.9% saline infusion for the prevention of contrast-induced acute kidney injury (BASIC trial): a study protocol for a randomized controlled trial

Background

Contrast-induced acute kidney injury (CI-AKI) is one of the most common causes of iatrogenic kidney injury and, therefore, its prevention is an important issue. However, whether the administration of 0.9% saline is the optimal prophylaxis method remains uncertain due to its supra-physiologic chloride component. In particular, recent studies suggest that chloride-restricted solutions showed superiority over 0.9% saline in several clinical settings.

Methods/design

The investigators designed a multicenter randomized controlled trial to compare the efficacy of a balanced salt solution and 0.9% saline in CI-AKI prophylaxis. This study will recruit patients who are scheduled for contrast-enhanced computed tomography (CT) scans with CI-AKI prophylaxis. In this study, participants will be randomized into two study arms; the study group will receive a balanced salt solution, and the control group will receive 0.9% saline. Fluids will be administered as designated in the protocol before and after the CT scan, and an evaluation of baseline clinical status will be performed by obtaining blood and urine samples. During the follow-up visits, the incidence of CI-AKI and long-term outcomes, including the start of renal replacement therapy or all-cause mortality, will be assessed.

Discussion

To our knowledge, this study will be the first study assessing the preventive value of a balanced salt solution over 0.9% saline for CI-AKI. If the trial shows that the balanced salt solution is as effective for CI-AKI prophylaxis as 0.9% saline, the use of the balanced salt solution could be promoted due to the reduced possibility of consequent metabolic acidosis compared to 0.9% saline.

Trials registration

ClinicalTrials.gov, ID: NCT02799368. Registered on 14 June 2016.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2202-2) contains supplementary material, which is available to authorized users.

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.

Histopathological Evaluation of Contrast-Induced Acute Kidney Injury Rodent Models

Contrast-induced acute kidney injury (CI-AKI) can occur in 3–25% of patients receiving radiocontrast material (RCM) despite appropriate preventive measures. Often patients with an atherosclerotic vasculature have to receive large doses of RCM. Thus, animal studies to uncover the exact pathomechanism of CI-AKI are needed. Sensitive and specific histologic end-points are lacking; thus in the present review we summarize the histologic appearance of different rodent models of CI-AKI. Single injection of RCM causes overt renal damage only in rabbits. Rats and mice need an additional insult to the kidney to establish a clinically manifest CI-AKI. In this review we demonstrate that the concentrating ability of the kidney may be responsible for species differences in sensitivity to CI-AKI. The most commonly held theory about the pathomechanism of CI-AKI is tubular cell injury due to medullary hypoxia. Thus, the most common additional insult in rats and mice is some kind of ischemia. The histologic appearance is tubular epithelial cell (TEC) damage; however severe TEC damage is only seen if RCM is combined by additional ischemia. TEC vacuolization is the first sign of CI-AKI, as it is a consequence of RCM pinocytosis and lysosomal fusion; however it is not sensitive as it does not correlate with renal function and is not specific as other forms of TEC damage also cause vacuolization. In conclusion, histopathology alone is insufficient and functional parameters and molecular biomarkers are needed to closely monitor CI-AKI in rodent experiments.

Contrast medium administration and image acquisition parameters in renal CT angiography: what radiologists need to know

Over the last decade, exponential advances in computed tomography (CT) technology have resulted in improved spatial and temporal resolution. Faster image acquisition enabled renal CT angiography to become a viable and effective noninvasive alternative in diagnosing renal vascular pathologies. However, with these advances, new challenges in contrast media administration have emerged. Poor synchronization between scanner and contrast media administration have reduced the consistency in image quality with poor spatial and contrast resolution. Comprehensive understanding of contrast media dynamics is essential in the design and implementation of contrast administration and image acquisition protocols. This review includes an overview of the parameters affecting renal artery opacification and current protocol strategies to achieve optimal image quality during renal CT angiography with iodinated contrast media, with current safety issues highlighted.

Intravenous Imaging Contrast Media Complications: The Basics That Every Clinician Needs to Know

Intravenous contrast is commonly used in noninvasive imaging procedures such as magnetic resonance imaging and computed tomography and can evaluate blood vessels and better characterize soft-tissue lesions. Although the incidence of adverse events after administration of contrast is low, it is important that clinicians and radiologists minimize risks and respond quickly and effectively when reactions occur. We will discuss a range of adverse events to iodinated and gadolinium-based contrast agents, including allergic-like reactions, nephrotoxicity, extravasation, and nephrogenic systemic fibrosis. We will review risk stratification for patients, as well as premedication and treatment of adverse events.

Imaging quality evaluation of low tube voltage coronary CT angiography using low concentration contrast medium

PURPOSE

To compare the image quality of prospectively ECG-gated low voltage coronary computed tomography angiography (CTA) with an administration of low concentration contrast medium.

METHOD AND MATERIALS

A total of 101 patients, each with a heart rate below 65 beats per minute (BPM), underwent a prospectively ECG-gated axial scan in CT coronary angiography on a 64-slice CT scanner. All patients were allocated in three groups (group A: n=31, 80 kVp, 300 mgI/ml; group B: n=34, 100 kVp, 300 mgI/ml; group C: n=36, 120 kVp, 370 mgI/ml). The CT attenuation values of aortic root (AR), left main coronary artery (LMA), right main coronary artery (RMA) and chest subcutaneous fat tissue were measured. The contrast-to-noise ratio (CNR) of AR, LMA and RMA were calculated according to the formulas below. The values of computed tomography dose index (CTDI) and dose-length product (DLP) were recorded. Image quality was assessed on a 5-point scale. The results were compared using the one-way ANOVA and rank sum tests.

RESULTS

The values of CNR and SNR for vessels in group A and group B were not significantly different from group C (each p > 0.05). The effective radiation dose in group A (1.51 ± 0.70 mSv) and group B (2.59 ± 1.24 mSv) were both lower than group C (4.92 ± 2.82 mSv) (each p < 0.05). There was no significant difference among the image quality scores of group A (4.10 ± 0.41), group B (3.90 ± 0.48) and group C (4.04 ± 0.36) (each P > 0.05).

CONCLUSION

Low tube voltage coronary CT angiography using low concentration contrast medium does not affect the imaging quality for assessing the coronary arteries compared with high voltage coronary CT angiography using high concentration contrast medium. Meanwhile low concentration contrast medium allowed 47-69% of radiation dose reduction.

Acute kidney injury after contrast-enhanced examination among elderly

OBJECTIVES

to assess renal function in elderly patients undergoing contrast-enhanced computed tomography and identify the preventive measures of acute kidney injury in the period before and after the examination.

METHOD

longitudinal cohort study conducted at the Federal University of São Paulo Hospital, from March 2011 to March 2013. All hospitalized elderly, of both sexes, aged 60 years and above, who performed the examination, were included (n=93). We collected sociodemographic data, data related to the examination and to the care provided, and creatinine values prior and post exam.

RESULTS

an alteration in renal function was observed in 51 patients (54%) with a statistically significant increase of creatinine values (p<0.04), and two patients (4.0%) required hemodialysis.

CONCLUSION

There is an urgent need for protocols prior to and post contrast-enhanced examination in the elderly, and other studies to verify the prognosis of this population.