Contrast-induced nephropathy: a clinical and evidence-based approach

Toward the Clinical Translation of Safe Intravenous Long Circulating Iodinated Lipid Nanoemulsion Contrast Agents for CT Imaging

Current clinical small molecule x-ray CT agents are effective but pose risks such as nephrotoxicity, short blood circulation time, limiting scan durations, potential thyroid impact, and immune responses. These challenges drive the development of kidney-safe x-ray nanoparticle (NP)-based contrast agents (CAs), though translation to clinical practice is hindered by chemical complexities and potential toxicity. We have engineered an intravenous, injectable, and safe blood pool NP-based CT CAs at a clinical-equivalent dose of ∼300 mgI/kg (∼2 mL/kg), ideal for vascular and hepatic imaging which are limited by clinical agents. Our iodinated lipid nanodroplet emulsions (ILNEs) contrast agent offers high x-ray attenuation thus improved contrast enhancement, extended stability, and exceptional batch-to-batch consistency. It also boasts a straightforward and scalable manufacturing process with minimal protein interaction, prolonged blood residency (∼4h), and hepatic clearance within 3 days, avoiding nephrotoxicity. Studies in vitro, in mice, and 16.6kg porcine animal model studies confirm its safety, cytocompatibility, and absence of tissue damage. Blood, and thyroid-stimulating hormone (TSH) analyses, and kidney and liver function tests, also support further toxicity evaluations for clinical translation.

Long-Term Effects of Acute Kidney Injury Following Endovascular Femoropopliteal Intervention: Insights From a Multicenter Trial

PURPOSE

To examine the association between acute kidney injury (AKI) severity and duration with cardiovascular mortality, following endovascular treatment of femoropopliteal disease, and whether it is AKI in itself that confers an increased risk of cardiovascular mortality.

METHODS

A retrospective analysis of prospectively collected data obtained between 2014 and 2019 from 3 vascular centers. Renal function was followed up for a minimum of 90 days. Electronic records were queried to establish a cause of death, where applicable. Patients were excluded if unable to provide written informed consent or if presenting with acute limb ischemia. Primary outcomes were the hazard ratios for cardiovascular death (AKI patients vs no AKI; no AKI vs stage 1 AKI vs stage 3 AKI; and no AKI vs transient AKI vs established AKI). Propensity score-matched analysis was used to establish whether developing AKI, in patients with similar demographics and procedural characteristics, is associated with a higher risk of cardiovascular death.

RESULTS

Overall 239 patients developed AKI, and this was associated with an increased risk of cardiovascular mortality (hazard risk [HR]: 4.3, 95% confidence intervals [CIs]: 2.1-6.8, pairwise comparison p value=0.006]. This was dependent on the severity of the AKI stage (HR 5.4, 95% CI: 2.4-7.3, pairwise comparison p value=0.01) and duration (HR 4.2, 95% CI: 2.3-6.2, pairwise comparison p value=0.04). The propensity score-matched analysis showed that even when patients are matched for comorbidity and procedural characteristics, AKI confers an increased risk of mortality (p=0.04).

CONCLUSIONS

Acute kidney injury is common after femoropopliteal endovascular therapy. It confers an increased risk of long-term cardiovascular mortality, which is still present when renal decline is transient, and highest for patients with established decline in renal function.

CLINICAL IMPACT

This is the first study in the setting of peripheral arterial disease to show that acute kidney injury has an adverse effect on cardiovascular mortality, in the long-term, that is dependent on its severity, and present even when the AKI is transient. We have also shown that this difference in cardiovascular mortality becomes more pronounced from the medium-term, and thus closer follow-up of these patients is required.

Evaluation of Emerging Predictors for Contrast-Induced Nephropathy in High-Risk Patients Undergoing Percutaneous Coronary Intervention

OBJECTIVE

The objective of this study is to investigate the occurrence and factors that influence the development of contrast-induced nephropathy (CIN) in high-risk patients undergoing angioplasty and to evaluate the effectiveness of the Mehran risk score in predicting CIN among this patient population.

MATERIALS AND METHOD

This prospective, observational study enrolled patients undergoing elective coronary angiography or a percutaneous coronary intervention (PCI) procedure. The patients were stratified into four risk groups based on the Mehran risk score, a validated tool for predicting the risk of CIN. Univariate and multivariate analyses were conducted to evaluate the risk factors associated with the development of CIN. A p-value of <0.05 was considered to indicate statistical significance.

RESULTS

During the study period, a total of 55 high-risk patients underwent PCI. The incidence of CIN was 25.5% (n=14). Univariate and multivariate analyses revealed that age >75 years and estimated glomerular filtration rate (eGFR) <60 (p<0.05) were independently associated with a significantly increased risk of developing CIN. A considerable proportion of patients (23; 41.8%) in the study were categorized as having an intermediate risk for CIN based on the Mehran risk score.

CONCLUSION

This study observed a high incidence of CIN and encourages the use of predictive tools like the Mehran risk score to assess the risk of CIN occurrence, with age over 70 years and eGFR less than 60 emerging as significant.

Deep Learning Image Reconstruction for Transcatheter Aortic Valve Implantation Planning: Image Quality, Diagnostic Performance, Contrast volume and Radiation Dose Assessment

RATIONALE AND OBJECTIVES

To assess image quality, contrast volume and radiation dose reduction potential and diagnostic performance with the use of high-strength deep learning image reconstruction (DLIR-H) in transcatheter aortic valve implantation (TAVI) planning CT.

METHODS

We prospectively enrolled 128 patients referred to TAVI-planning CT. Patients were randomly divided into two groups: DLIR-H group (n = 64) and conventional group (n = 64). The DLIR-H group was scanned with tube voltage of 80kVp and body weighted-dependent contrast injection rate of 28mgI/kg/s, images reconstructed using DLIR-H; the conventional group was scanned with 100kVp and contrast injection rate of 40mgI/kg/s, and images reconstructed using adaptive statistical iterative reconstruction-V at 50% (ASIR-V 50%). Radiation dose, contrast volume, contrast injection rate, and image quality were compared between the two groups. The diagnostic performance of TAVI planning CT for coronary stenosis in 115 patients were calculated using invasive coronary angiography as golden standard.

RESULTS

DLIR-H group significantly reduced radiation dose (4.94 ± 0.39mSv vs. 7.93 ± 1.20mSv, p < 0.001), contrast dose (45.28 ± 5.38 mL vs. 63.26 ± 9.88 mL, p < 0.001), and contrast injection rate (3.1 ± 0.31 mL/s vs. 4.9 ± 0.2 mL/s, p < 0.001) compared to the conventional group. Images in DLIR-H group had significantly higher SNR and CNR (all p < 0.001). For the diagnostic performance on a per-patient basis, TAVI planning CT in the DLIR-H group provided 100% sensitivity, 92.1% specificity, 100% negative predictive value (NPV), and 84.2% positive predictive value for the detection of > 50% stenosis. In the conventional group, the corresponding results were 94.7%, 95.3%, 97.6%, and 90.0%, respectively.

CONCLUSION

DLIR-H in TAVI-planning CT provides improved image quality with reduced radiation and contrast doses, and enables satisfactory diagnostic performance for coronary arteries stenosis.

Contrast-induced acute kidney injury: a review of definition, pathogenesis, risk factors, prevention and treatment

Contrast-induced acute kidney injury (CI-AKI) has become the third leading cause of hospital-acquired AKI, which seriously threatens the health of patients. To date, the precise pathogenesis of CI-AKI has remained not clear and may be related to the direct cytotoxicity, hypoxia and ischemia of medulla, and oxidative stress caused by iodine contrast medium, which have diverse physicochemical properties, including cytotoxicity, permeability and viscosity. The latest research shows that microRNAs (miRNAs) are also involved in apoptosis, pyroptosis, and autophagy which caused by iodine contrast medium (ICM), which may be implicated in the pathogenesis of CI-AKI. Unfortunately, effective therapy of CI-AKI is very limited at present. Therefore, effective prevention of CI-AKI is of great significance, and several preventive options, including hydration, antagonistic vasoconstriction, and antioxidant drugs, have been developed. Here, we review current knowledge about the features of iodine contrast medium, the definition, pathogenesis, molecular mechanism, risk factors, prevention and treatment of CI-AKI.

Feasibility of Low-Dose and Low-Contrast Media Volume Approach in Computed Tomography Cardiovascular Imaging Reconstructed with Model-Based Algorithm

Aim: To evaluate the dose reduction and image quality of low-dose, low-contrast media volume in computed tomography (CT) examinations reconstructed with the model-based iterative reconstruction (MBIR) algorithm in comparison with the hybrid iterative (HIR) one. Methods: We prospectively enrolled a total of 401 patients referred for cardiovascular CT, evaluated with a 256-MDCT scan with a low kVp (80 kVp) reconstructed with an MBIR (study group) or a standard HIR protocol (100 kVp-control group) after injection of a fixed dose of contrast medium volume. Vessel contrast enhancement and image noise were measured by placing the region of interest (ROI) in the left ventricle, ascending aorta; left, right and circumflex coronary arteries; main, right and left pulmonary arteries; aortic arch; and abdominal aorta. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were computed. Subjective image quality obtained by consensus was assessed by using a 4-point Likert scale. Radiation dose exposure was recorded. Results: HU values of the proximal tract of all coronary arteries; main, right and left pulmonary arteries; and of the aorta were significantly higher in the study group than in the control group (p < 0.05), while the noise was significantly lower (p < 0.05). SNR and CNR values in all anatomic districts were significantly higher in the study group (p < 0.05). MBIR subjective image quality was significantly higher than HIR in CCTA and CTPA protocols (p < 0.05). Radiation dose was significantly lower in the study group (p < 0.05). Conclusions: The MBIR algorithm combined with low-kVp can help reduce radiation dose exposure, reduce noise, and increase objective and subjective image quality.

Serum total bilirubin level is associated with contrast induced nephropathy after primary percutaneous coronary intervention

Contrast Induced Nephropathy (CIN) is a major complication of angiographic procedures. Primary percutaneous coronary intervention (pPCI) is the preferred treatment for ST-segment elevation myocardial infarction (STEMI) but is associated with a risk of CIN. Oxidative stress and free radical damage play a role in the pathogenesis of CIN. Bilirubin has anti-inflammatory and antioxidant activity and has been shown to have a protective effect on endothelial cells. The present study aimed to assess the association between serum bilirubin level and development of CIN after pPCI. Sequential STEMI patients (n = 595) who underwent pPCI between January 2021 and December 2022 were enrolled. Among the participants, 116 (19.5%) developed CIN. Serum total bilirubin level was significantly lower in the CIN group (P = .001). In multivariate logistic regression analysis, serum bilirubin level was found as an independent predictor of CIN. Age, gender, contrast volume, and white blood cell count were other independent predictors of CIN. A higher serum bilirubin level is associated with a lower risk of CIN in the present study. In STEMI patients undergoing pPCI, serum bilirubin level may be helpful to predict the risk of CIN and may help ensure early initiation of preventive treatment and careful follow-up.

Contrast-Associated Acute Kidney Injury in High-Risk Patients Undergoing Peripheral Vascular Interventions

Objective: This study aims to evaluate the use of prophylactic intravenous hydration (IV prophylaxis) and carbon dioxide (CO₂) angiography in reducing contrast associated-acute kidney injury (CA-AKI) and determine the overall incidence and risk factors of CA-AKI in high-risk patients undergoing peripheral vascular interventions (PVI). Method: Only patients undergoing elective PVI from 2017 to 2021 with chronic kidney disease (CKD) stage 3-5 in the Vascular Quality Initiative (VQI) database were included. Patients were grouped into IV prophylaxis vs no prophylaxis. The study's primary outcome was CA-AKI, defined as a rise in creatinine (>.5 mg/dL) or new dialysis within 48 hours following contrast administration. Standard univariate and multivariable (logistic regression) analyses were conducted. Results: A total of 4497 patients were identified. Of these, 65% received IV prophylaxis. The overall incidence of CA-AKI was .93%. No significant difference was seen in overall contrast volume (mean (SD): 66.89(49.54) vs 65.94(51.97) milliliters, P > .05) between the 2 groups. After adjusting for significant covariates, the use of IV prophylaxis (OR (95% CI): 1.54(.77-3.18), P = .25) and CO₂ angiography (OR (95%CI): .95(.44-2.08), P = .90) was not associated with a significant reduction in CA-AKI compared to the patients with no prophylaxis. The severity of CKD and diabetes were the only predictor of CA-AKI. Compared to patients with no CA-AKI, patients with CA-AKI were at risk of higher 30-day mortality (OR (95% CI): 11.09 (4.25-28.93)) and cardiopulmonary complications (OR (95% CI): 19.03 (8.74-41.39) following PVI (Both P < .001). Conclusion: Using a large national vascular database, our study demonstrates that prophylactic use of IV hydration and CO₂ angiography in high-risk CKD patients is not associated with a reduction in renal injury following PVI. Reduced kidney function and history of diabetes is an independent predictor of CA-AKI and patients that develop post-procedural AKI are at an increased risk of morbidity and mortality.

The triglyceride-glucose index and contrast-induced nephropathy in non-ST elevation myocardial infarction patients undergoing percutaneous coronary intervention

The triglyceride glucose (TyG) index is an indicator of insulin resistance and associated with increased risk of diabetes mellitus and cardiovascular events. Our study investigates the correlation between TyG index and contrast induced nephropathy (CIN) in non-diabetic patients with non-ST elevation myocardial infarction (NSTEMI) undergoing percutaneous coronary intervention (PCI). 350 non-diabetic NSTEMI patients (183, 52.3% male) undergoing PCI were retrospectively enrolled. The enrolled cohort was divided into 2 groups based on the calculated TyG index, namely values < 8.65 or higher. CIN was defined as an increase in serum creatinine > 25% or 0.5 mg/dL from baseline in the first 48 to 72 hours after PCI. A total of 56 (16%) cases of CIN were diagnosed. In contrast to patients with lower TyG indexes, patients with higher TyG indexes (≥8.65) had a higher frequency of CIN, 9.5%. versus 20.8% respectively (P .004). Patients with CIN also had higher TyG indexes (8.74 ± 0.12 vs 8.67 ± 0.11, P < .001). In addition, TyG index, age, and glomerular filtration rate were identified as independent risk factors for CIN in logistic regression model (OR: 2.5 CI: 1.3-4.6, P .006, OR: 1.0 CI: 1.0-1.1, P < .001, OR: 1.0 KI: 1.03-1.06, P .025). In the ROC analysis, the area under the curve predictive of CIN was 0.666 (P < .001, 95% [CI] 0.58-0.75) with a cutoff value of 8.69 (sensitivity 71,4%, specificity 55.1%) TyG index. Higher TyG indexes are associated with an increased risk of CIN in non-diabetic patients with NSTEMI.

A multiple-metabolites model to predict preliminary renal injury induced by iodixanol based on UHPLC/Q-Orbitrap-MS and 1H-NMR

BACKGROUND & AIMS

There are some problems, such as unclear pathological mechanism, delayed diagnosis, and inaccurate therapeutic target of Contrast-induced acute kidney injury (CI-AKI). It is significantly important to find biomarkers and therapeutic targets that can indicate renal injury in the early stage of CI-AKI. This study aims to establish a multiple-metabolites model to predict preliminary renal injury induced by iodixanol and explore its pathogenesis.

METHODS

Both UHPLC/Q-Orbitrap-MS and ¹H-NMR methods were applied for urine metabolomics studies on two independent cohorts who suffered from a preliminary renal injury caused by iodixanol, and the multivariate statistical analysis and random forest (RF) algorithm were used to process the related date.

RESULTS

In the discovery cohort (n = 169), 6 metabolic markers (leucine, indole, 5-hydroxy-L-tryptophan, N-acetylvaline, hydroxyhexanoycarnine, and kynurenic acid) were obtained by the cross-validation between the RF and liquid chromatography-mass spectrometry (LC-MS). Secondly, the 6 differential metabolites were confirmed by comparison of standard substance and structural identification of ¹H-NMR. Subsequently, the multiple-metabolites model composed of the 6 biomarkers was validated in a validation cohort (n = 165).

CONCLUSIONS

The concentrations of leucine, indole, N-acetylvaline, 5-hydroxy-L-tryptophan, hydroxyhexanoycarnitine and kynurenic acid in urine were proven to be positively correlated with the degree of renal injury induced by iodixanol. The multiple-metabolites model based on these 6 biomarkers has a good predictive ability to predict early renal injury caused by iodixanol, provides treatment direction for injury intervention and a reference for reducing the incidence of clinical CI-AKI further.

Ytterbium Nanoparticle Contrast Agents for Conventional and Spectral Photon-Counting CT and Their Applications for Hydrogel Imaging

Significant work has been done to develop nanoparticle contrast agents for computed tomography (CT), with a focus on identifying safer and more effective formulations. Contrast agents for spectral photon-counting computed tomography (SPCCT), a fast-growing imaging modality derived from conventional CT, have also recently gained considerable attention. In this study, we explored the synthesis of ultrasmall ytterbium nanoparticles (YbNP) and demonstrated that, potentially, they can be used as conventional CT and SPCCT contrast agents. These nanoparticles were tested in vitro for their cytotoxicity and contrast-generating properties with a variety of imaging systems. When scanned with conventional CT and SPCCT at clinically relevant energies, YbNP are significantly more attenuating than gold nanoparticles (AuNP), the contrast agents that have been most well studied. Furthermore, YbNP were studied for their potential application for labeling and monitoring hydrogels. The presence of the YbNP payload in hydrogels allowed for hydrogel localization and tracking in vivo. Additionally, the in vivo imaging results revealed that YbNP generate higher contrast when compared to AuNP used as a label. In summary, this is the first research study to examine ultrasmall YbNP as conventional CT and SPCCT contrast agents, as well as using them in a hydrogel system to make it radiopaque. These findings underscore YbNP's utility as CT and SPCCT contrast agents, as well as their potential for tracking hydrogels in vivo.

Biocompatible carbonized iodine-doped dots for contrast-enhanced CT imaging

Background

Computed tomography (CT) imaging has been widely used for the diagnosis and surveillance of diseases. Although CT is attracting attention due to its reasonable price, short scan time, and excellent diagnostic ability, there are severe drawbacks of conventional CT contrast agents, such as low sensitivity, serious toxicity, and complicated synthesis process. Herein, we describe iodine-doped carbon dots (IDC) for enhancing the abilities of CT contrast agents.

Method

IDC was synthesized by one-pot hydrothermal synthesis for 4 h at 180 ℃ and analysis of its structure and size distribution with UV–Vis, XPS, FT-IR, NMR, TEM, and DLS. Furthermore, the CT values of IDC were calculated and compared with those of conventional CT contrast agents (Iohexol), and the in vitro and in vivo toxicities of IDC were determined to prove their safety.

Results

IDC showed improved CT contrast enhancement compared to iohexol. The biocompatibility of the IDC was verified via cytotoxicity tests, hemolysis assays, chemical analysis, and histological analysis. The osmotic pressure of IDC was lower than that of iohexol, resulting in no dilution-induced contrast decrease in plasma.

Conclusion

Based on these results, the remarkable CT contrast enhancement and biocompatibility of IDC can be used as an effective CT contrast agent for the diagnosis of various diseases compared with conventional CT contrast agents.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40824-022-00277-3.

Imaging of the Left Atrial Appendage Before Occluder Device Placement: Evaluation of Virtual Monoenergetic Images in a Single-Bolus Dual-Phase Protocol

PURPOSE

Preimplantation cardiac computed tomography (CT) for assessment of the left atrial appendage (LAA) enables correct sizing of the device and the detection of contraindications, such as thrombi. In the arterial phase, distinction between false filling defects and true thrombi can be hampered by insufficient contrast medium distribution. A delayed scan can be used to further differentiate both conditions, but contrast in these acquisitions is relatively lower. In this study, we investigated whether virtual monoenergetic images (VMI) from dual-energy spectral detector CT (SDCT) can be used to enhance contrast and visualization in the delayed phase.

MATERIALS AND METHODS

Forty-nine patients receiving SDCT imaging of the LAA were retrospectively enrolled. The imaging protocol comprised dual-phase acquisitions with single-bolus contrast injection. Conventional images (CI) from both phases and 40-keV VMI from the delayed phase were reconstructed. Attenuation, signal-, and contrast-to-noise ratios (SNR/CNR) were calculated by placing regions-of-interest in the LAA, left atrium, and muscular portion of interventricular septum. Two radiologists subjectively evaluated conspicuity and homogeneity of contrast distribution within the LAA.

RESULTS

Contrast of the LAA decreased significantly in the delayed phase but was significantly improved by VMI, showing comparable attenuation, SNR, and CNR to CI from the arterial phase (attenuation/SNR/CNR, CI arterial phase: 266.0 ± 117.0 HU/14.2 ± 7.2/6.6 ± 3.9; CI-delayed phase: 107.6 ± 35.0 HU/5.9 ± 3.0/1.0 ± 1.0; VMI delayed phase: 260.3 ± 108.6 HU/18.2 ± 10.6/4.8 ± 3.4). The subjective reading confirmed the objective findings showing improved conspicuity and homogeneity in the delayed phase.

CONCLUSIONS

The investigated single-bolus dual-phase acquisition protocol provided improved visualization of the LAA. Homogeneity of contrast media was higher in the delayed phase, while VMI maintained high contrast.

Capsaicin Prevents Contrast-Associated Acute Kidney Injury through Activation of Nrf2 in Mice

Capsaicin, a transient receptor potential vanilloid 1 channel agonist, possesses antioxidative properties through activating nuclear factor-erythroid 2-related factor 2 (Nrf2). As oxidative stress is a major contributor to the development of contrast-associated acute kidney injury (CA-AKI), we investigated the protective effect of capsaicin against CA-AKI via Nrf2. C57BL/6J mice were treated with dehydration and iodixanol to establish the model of CA-AKI. For pretreatment, capsaicin (0.3 mg/kg) was given via intraperitoneal injection one hour before iodixanol injection. Nrf2-specific siRNA was given through the tail vein to knock down Nrf2. The CA-AKI mouse model had remarkable mitochondrial fragmentation and dysfunction and apoptosis of tubular cells, overproduction of superoxide in renal tubules, increased renal malondialdehyde, tubular epithelial cell injury, and renal dysfunction. Importantly, pretreatment with capsaicin significantly ameliorated tubular cell injury and renal dysfunction with decreased superoxide, renal malondialdehyde, and apoptotic tubular cells and improved mitochondrial morphology and function in the CA-AKI mouse model. The expression of Nrf2 was increased in the kidney from the CA-AKI mouse model and was further enhanced by capsaicin. Administration of siRNA through the tail vein successfully decreased Nrf2 expression in the kidney, and knockdown of Nrf2 by siRNA abolished the beneficial effects of capsaicin on CA-AKI. The present study demonstrated a protective effect of capsaicin pretreatment against CA-AKI via Nrf2.

Efficacy of brain natriuretic peptide vs. nicorandil in preventing contrast-induced nephropathy: a network meta-analysis

This study aimed to conduct a network meta-analysis (NMA) to compare the efficacy of brain natriuretic peptide (BNP) vs nicorandil for preventing contrast-induced nephropathy (CIN). Databases of Pubmed, Cochrane, Embase, Web of Science were searched by keywords for eligible studies of randomized controlled trials investigating different agents (BNP, nicorandil, nitroglycerin, intravenous saline) for preventing CIN. The outcomes included a change in serum creatinine level at 48 h and the incidence of CIN after percutaneous coronary intervention (PCI) or coronary angiography (CAG). A total of 13 studies with 3,462 patients were included. Compared with intravenous saline alone, except for nitroglycerin (odds ratio [OR]: 1.02, 95% CI [0.36-2.88]), the other drugs significantly reduced the CIN incidence with OR of 0.35 (95% CI [0.24-0.51]) for BNP, 0.52 (0.29, 0.94) for usual-dose nicorandil, 0.28 (0.19, 0.43) for double-dose nicorandil. BNP and double-dose nicorandil significantly decreased the change of serum creatinine (SCr) levels with mean difference (MD) of -6.98, (-10.01, -3.95) for BNP, -8.78, (-11.63, -5.93) for double-dose nicorandil. No significant differences were observed in the change of SCr levels for nitroglycerin (-4.97, [-11.46, 1.52]) and usual-dose nicorandil (-2.32, [-5.52, 0.89]) compared with intravenous saline alone. For double-dose nicorandil, the CIN incidence and the change of SCr level in group of 4-5 days treatment course were more than group of less than or equal to 24 h treatment course (OR of 1.48, [0.63-3.46] and MD of 2.48, [-1.96, 6.91]). In conclusion, BNP and double-dose nicorandil can have effects on preventing the incidence of CIN and double-dose nicorandil performed better than BNP. In double-dose nicorandil groups, a course of less than or equal to 24 h before and after procedure performed with better efficacy than a course of 4-5 days.

Effect of Oral Hydration on Contrast-Induced Acute Kidney Injury among Patients after Primary Percutaneous Coronary Intervention

OBJECTIVES

The purpose of this study was to evaluate the protective effect of oral hydration volume to weight ratio (OHV/W) on contrast-induced acute kidney injury (CI-AKI) among patients with ST-elevation myocardial infarction (STEMI) following percutaneous coronary intervention (PCI).

METHODS

A total of 754 patients with STEMI undergoing PCI were selected. Each patient was encouraged to drink as much water as possible 24 h after PCI. Total volume intake was recorded for all patients. The ratio of OHV/W was calculated. The occurrence of CI-AKI was defined as ≥0.5 mg/dL absolute or ≥25% relative increase in serum creatinine within 48-72 h following PCI. Logistic regression analysis and generalized additive model were performed to evaluate the relationship between OHV/W and CI-AKI.

RESULTS

There was a nonlinear relationship between OHV/W and CI-AKI with an inflection point of 15.69 mL/kg. On the right side of the inflection point (OHV/W ≥15.69 mL/kg), a negative relationship was detected between OHV/W and CI-AKI (HR = 0.90, 95% CI: 0.82∼0.98, p = 0.0126). However, no relationship was observed between OHV/W and CI-AKI on the left of inflection point (HR = 1.19, 95% CI: 0.95∼1.49, p = 0.1302). Subgroup analysis showed that significant interactions were observed only for gender difference (p for interaction = 0.0155), male patients had a significantly lower risk of CI-AKI (HR = 0.84, 95% CI: 0.75∼0.93, p = 0.0012).

CONCLUSION

OHV/W ≥15.6 mL/kg for 24 h post-procedure may be an effective preventive strategy of CI-AKI. In addition, male patients may particularly benefit from OHV to prevent CI-AKI.

Safety and Efficacy of Hybrid Angiography in Chronic Lower Extremity Ischemia Patients at Risk of Contrast-Induced Acute Kidney Injury

AIM

The aim of the study was to assess the feasibility and safety of hybrid angiography consisting of carbon dioxide (CO₂) angiography supplemented by small doses of iodinated contrast medium (ICM) in the endovascular treatment of chronic limb threatening ischemia (CLTI) patients with pre-existing chronic kidney disease (CKD).

PATIENTS AND METHODS

This prospective study comprised all non-dialysis-dependent CKD patients presenting for endovascular management of CLTI. All endovascular interventions were done using CO₂ as a contrast medium whether alone or supplemented by ICM (hybrid angiography) to treat unilateral arterial steno-occlusive lesions of iliac, femoropopliteal, or BTK arteries. Study outcomes included feasibility of the device, technical success, and freedom from contrast-induced acute kidney injury (CI-AKI), renal replacement therapy, and CO₂ angiography-related complications.

RESULTS

A total of 206 CKD patients underwent endovascular intervention using CO₂ only as a contrast medium (159 patients, 77.2%), or hybrid CO₂-ICM angiography (47 patients, 22.8%). The overall technical success was 95.6%. Patients were followed up for a mean period of 17.9 ± 4.6 months. The mean volumes of CO₂, and ICM consumption were 200.7 ± 95.1 mL, and 11.8 ± 4.4 mL, respectively. The mean procedural, and fluoroscopy times were 95.6 ± 12.5 and 49.5 ± 10.8 minutes, respectively. BTK lesions were significantly associated with the need for hybrid angiography (P = <.0001). The mean pre- and postoperative serum creatinine levels were comparable (P = .08). Two patients (4.3%) showed transient manifestations of CI-AKI, but neither required renal replacement therapy. No statistically significant differences were encountered between the two study groups regarding procedure outcomes.

CONCLUSION

Hybrid CO₂-ICM angiography is safe, feasible, effective, and a fairly simple alternative during endovascular interventions to treat chronic lower extremity ischemia. Using supplemental small volumes of ICM to overcome the suboptimal images generated by CO₂ alone does not jeopardize the renal functions in CKD patients.

Calorie Restriction Protects against Contrast-Induced Nephropathy via SIRT1/GPX4 Activation

Calorie restriction (CR) extends lifespan and increases resistance to multiple forms of stress, including renal ischemia-reperfusion (I/R) injury. However, whether CR has protective effects on contrast-induced nephropathy (CIN) remains to be determined. In this study, we evaluated the therapeutic effects of CR on CIN and investigated the potential mechanisms. CIN was induced by the intravenous injection of iodinated contrast medium (CM) iopromide (1.8 g/kg) into Sprague Dawley rats with normal food intake or 40% reduced food intake, 4 weeks prior to iopromide administration. We found that CR was protective of CIN, assessed by renal structure and function. CM increased apoptosis, reactive oxygen species (ROS), and inflammation in the renal outer medulla, which were decreased by CR. The silent information regulator 1 (SIRT1) participated in the protective effect of CR on CIN, by upregulating glutathione peroxidase 4 (GPX4), a regulator of ferroptosis, because this protective effect was reversed by EX527, a specific SIRT1 antagonist. Our study showed that CR protected CIN via SIRT1/GPX4 activation. CR may be used to mitigate CIN.

Poor Prognosis of Contrast-Induced Nephropathy during Long Term Follow Up

Contrast-induced nephropathy (CIN) is known to associate with poor prognosis. However, there have been few studies for long-term follow up. The purpose of this study was to know the prognosis of CIN during a 10-year follow up. We retrospectively analyzed 528 patients who underwent coronary angiography in Jeonbuk National University Hospital (South Korea, Jeonju) between Jan 2005 to Dec 2006. We excluded the patients who required regular dialysis before study enrollment. We compared adverse events in the no CIN (group I, n=485, 61.9±11.4 years, male 64.1%) and CIN (group II, n=43, 65.7±11.1 years, male 62.8%). Baseline clinical characteristics and cardiovascular risk factors were not different between the two groups except the post-procedure creatinine level (1.04 mg/dL vs 1.84 mg/dL, p=0.0001). The higher rates of all-cause death were observed in group II at 1-year (3.7% vs 13.9%, log-rank, p=0.001), 5-years (17.9% vs 34.9%, log-rank, p=0.003), and 10-years (25.3% vs 48.8%, log-rank, p=0.000). MACE was higher in group II at 1-year (3.9% vs 11.6%, log-rank, p=0.013), 5-years (6.8% vs 20.9%, log-rank, p=0.000) and 10-years (13.4% vs 27.9%, log-rank, p=0.000). In addition, CIN was an independent predictor for 10-year MACE (adjusted HR 3.432, 95% CI 1.314-8.965, p=0.012) after propensity score matching. The worse prognosis of CIN was continuously observed after the 10-year follow-up. Our data suggests that it is worthwhile to prevent the appearance of CIN in order to improve longterm results.

The potential of iodinated contrast reduction in dual-energy CT thoracic angiography; an evaluation of image quality

INTRODUCTION

The purpose of this study was to compare a dual energy CT (DECT) protocol with 50% reduction of iodinated contrast to a single energy CT (SECT) protocol using standard contrast dose in imaging of the thoracic aorta.

METHODS

DECT with a 50% reduction in iodinated contrast was compared with SECT. For DECT, monoenergetic images at 50, 55, 60, 65, 68, 70, and 74 keV were reconstructed with adaptive statistical iterative reconstruction (ASiR-V) of 50% and 80%. Objective image quality parameters included intravascular attenuation (HU), image noise (SD), contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR). Two independent radiologists subjectively assessed the image quality for the 55 and 68 keV DECT reconstructions and SECT on a five-point Likert scale.

RESULTS

Across 14 patients, the intravascular attenuation at 50-55 keV was comparable to SECT (p > 0.05). The CNRs were significantly lower for DECT with ASIR-V 50% compared to SECT for all keV-values (p < 0.05 for all). For ASIR-V 80%, CNR was comparable to SECT at energies below 60 keV (p > 0.05). The subjective image quality was comparable between DECT and SECT independent of keV level.

CONCLUSION

This study indicates that a 50% reduction in iodinated contrast may result in adequate image quality using DECT with monoenergetic reconstructions at lower energy levels for the imaging of the thoracic aorta. The best image quality was obtained for ASiR-V 80% image reconstructions at 55 keV.

IMPLICATIONS OF PRACTICE

Dual energy CT with a reduction in iodinated contrast may result in adequate image quality in imaging of the thoracic aorta. However, increased radiation dose may limit the use to patients in which a reduction in fluid and iodinated contrast volume may outweigh this risk.

Association between plasma endothelial microparticles and contrast-induced nephropathy in patients underwent coronary angiography

We aim to investigate the association between plasma endothelial microparticles (EMPs) and contrast-induced nephropathy of patients underwent coronary angiography.The patients were divided into normal renal function group and renal dysfunction group based on the estimated glomerular filtration rate (eGFR). Among the 180 cases, 117 received determination of EMP and serum creatinine after percutaneous coronary intervention (PCI) and/or coronary angiography. The patients were divided into contrast-induced-nephropathy (CIN) group and non-CIN group. EMPs collection and determination were performed, together with biochemical analysis and digital subtraction angiography (DSA) analysis.Spearman correlation showed that the expression of EMP was negatively correlated with eGFR (r = -0.201, P < .01). The serum hypersensitive C-reactive protein (hs-CRP), cystatin C (Cys-C), uric acid (UA) were significantly higher in CIN group than that in the non CIN group. Spearman correlation showed that the expression of EMP was positively correlated with serum interleukin-6 (IL-6, r = 0.393, P < .01). The expression of EMP was positively correlated with serum hs-CRP (r = 0.360, P < .01). Logistic regression analysis showed that the levels of N-terminal pro-brain natriuretic peptide (NT-proBNP), eGFR, UA, and Cys-C were correlated with the incidence of contrast induced nephropathy.In patients with contrast-induced-nephropathy, the plasma EMPs were significantly increased after coronary angiography. The expression of plasma EMPs may play a role in the occurrence of contrast-induced-nephropathy.

Acute kidney injury following endovascular intervention for peripheral artery disease

BACKGROUND

The incidence of, and risk factors for, acute kidney injury (AKI) after endovascular intervention for peripheral artery disease (PAD) remain unknown. The aim of this study was to assess the proportion of patients who develop AKI and explore the risk factors.

METHODS

Prospectively collected data on patients undergoing femoropopliteal endovascular intervention for symptomatic PAD across three vascular centres were analysed. The proportion of patients developing AKI (according to the Kidney Disease Improving Global Outcomes definition) within 48 h, and the proportion developing the composite Major Adverse Kidney Events (MAKE) endpoints (death, dialysis, drop in estimated glomerular filtration rate at least 25 per cent) at 30 days (MAKE30) and remains 90 days (MAKE90) were calculated. Multivariable regression analysis was used to assess predictors of AKI, and the association between AKI and death.

RESULTS

Some 2041 patients were included in the analysis. AKI developed in 239 patients (11.7 per cent), with 47 (2.3 per cent) requiring dialysis within 30 days, and 18 (0.9 per cent) requiring ongoing dialysis. The MAKE30 and MAKE90 composite endpoints were reached in 358 (17.5 per cent) and 449 (22.0 per cent) patients respectively. Risk factors for AKI were age, sex, congestive heart failure, chronic limb-threatening ischaemia, emergency procedure, and pre-existing chronic kidney disease. AKI, dementia, congestive heart failure, and major amputation were risk factors for medium-term mortality.

CONCLUSION

AKI is a common complication after intervention for PAD and is associated with medium-term mortality.

Ischemic Nephropathy Following Occlusion of Abdominal Aortic Aneurysm Graft: A Case Report

In this report, we present a case of a 55-year-old female with a past medical history of abdominal aortic aneurysm (AAA) graft, femoral-femoral bypass graft, questionable history of chronic kidney disease (CKD), abdominal hernia repair, alcoholic pancreatitis, chronic abdominal pain on opioids, and tobacco abuse who presented with acute on chronic abdominal pain with an unexplained rise of creatinine and anuria. The patient was found to have complete occlusion of AAA graft and was determined to have ischemic nephropathy (IN).

MG53 protects against contrast-induced acute kidney injury by reducing cell membrane damage and apoptosis

Mitsugumin 53 (MG53) is a tripartite motif family protein that has been reported to attenuate injury via membrane repair in different organs. Contrast-induced acute kidney injury (CI-AKI) is a common complication caused by the administration of iodinated contrast media (CM). While the cytotoxicity induced by CM leading to tubular cell death may be initiated by cell membrane damage, we wondered whether MG53 alleviates CI-AKI. This study was designed to investigate the effect of MG53 on CI-AKI and the underlying mechanism. A rat model of CI-AKI was established, and CI-AKI induced the translocation of MG53 from serum to injury sites on the renal proximal tubular (RPT) epithelia, as illustrated by immunoblot analysis and immunohistochemical staining. Moreover, pretreatment of rats with recombinant human MG53 protein (rhMG53, 2 mg/mL) alleviated iopromide-induced injury in the kidney, which was determined by measuring serum creatinine, blood urea nitrogen and renal histological changes. In vitro studies demonstrated that exposure of RPT cells to iopromide (20, 40, and 80 mg/mL) caused cell membrane injury and cell death, which were attenuated by rhMG53 (10 and 50 μg/mL). Mechanistically, MG53 translocated to the injury site on RPT cells and bound to phosphatidylserine to protect RPT cells from iopromide-induced injury. In conclusion, MG53 protects against CI-AKI through cell membrane repair and reducing cell apoptosis; therefore, rhMG53 might be a potential effective means to treat or prevent CI-AKI.

Avoiding the emergence of contrast-induced acute kidney injury in acute coronary syndrome: routine hydration treatment

BACKGROUND

Patients with acute coronary syndrome (ACS) have about a three-fold risk for developing contrast-induced acute kidney injury(CI-AKI). Investigating studies on routine hydration therapy have frequently included patients with stable coronary artery disease and high risk of CI-AKI [estimated glomerular filtration rate (eGFR) < 60 ml/min]. However, data on routine hydration treatment in non-ST segment elevation myocardial infarction (NSTEMI) patients with eGFR ≥60 ml/min are insufficient. We aimed to investigate the association between routine hydration therapy and CI-AKI development in NSTEMI patients at low risk for nephropathy.

METHODS AND RESULTS

We randomly assigned a total of 401 NSTEMI patients to two groups: the routine hydration group (198 patients) and the nonhydration group (control group) (203 patients). Intravenous hydration with isotonic saline (1 ml/kg/h, 0.9% sodium chloride) was given for 3-12 h before and 24 h after contrast exposure to the hydration group. CI-AKI was defined as the increase in serum creatinine values 0.5 mg/dl or 25% between 48 and 72 h after the invasive procedures. In our study, the incidence of CI-AKI development in the routine hydration group (7.1%) was significantly lower than in the nonhydration group (14.1%) (P: 0.02). This study revealed that older age, amount of contrast media, and routine hydration were independent risk factors for developing CI-AKI (P < 0.01, P: 0.04, P < 0.01, respectively).

CONCLUSION

We found that preprocedural and postprocedural intravenous hydration therapy reduces the development of CI-AKI in patients with NSTEMI at low risk for CI-AKI. We suggest administering routine hydration therapy in all ACS patients regardless of eGFR values.

Remote ischemic preconditioning for prevention of contrast-induced nephropathy - A randomized control trial

Background

There is a lack of sufficient data regarding the protective effects of remote ischemic preconditioning (RIPC) in patients at risk of developing contrast-induced nephropathy (CIN). Thus, this study was conducted to determine whether RIPC as an adjunct to standard therapy prevents CIN in high-risk patients undergoing coronary intervention.

Methods

In a single-center, double-blinded, randomized controlled trial, 162 patients who were at risk of CIN received standard hydration combined with RIPC or hydration with sham preconditioning. RIPC was accomplished by four cycles of 5 min ischemia and 5 min reperfusion of the forearm. The primary endpoint was a rise in serum creatinine (>0.5 mg/dL or >25%) from baseline to serum creatinine 48–72 h after contrast administration.

Results

Of the 162 patients, 81 were randomly allocated to receive sham preconditioning and 81 to receive RIPC. Significantly reduced serum creatinine levels were observed in patients with a Mehran moderate risk allocated to sham group compared to the RIPC group (0.070 ± 0.16 mg/dL vs. 0.107 ± 0.13 mg/dL, p = 0.001). With regards to the primary endpoint, a significantly higher change in serum creatinine from baseline to 48–72 h was observed in the sham group compared to the RIPC group (0.023 ± 0.2 μmol/L vs −0.064 ± 0.1 μmol/L, p < 0.001).

Conclusion

RIPC as an alternative to standard therapy, improved serum creatinine levels after contrast administration in patients at risk of CIN. However, present data indicate that RIPC might have beneficial effects in patients with a moderate or high risk of CIN.

Virtual monoenergetic images preserve diagnostic assessability in contrast media reduced abdominal spectral detector CT

OBJECTIVES

To investigate if low-keV virtual monoenergetic images (VMI_40keV) from abdominal spectral detector CT (SDCT) with reduced intravenous contrast media application (RCM) provide abdominal assessment similar to conventional images with standard contrast media (SCM) dose.

METHODS

78 patients with abdominal SDCT were retrospectively included: 41 patients at risk for adverse reactions who received 44 RCM examinations with 50 ml and 37 patients who underwent 44 SCM examinations with 100 ml of contrast media (CM) and who were matched for effective body diameters. RCM, SCM images and RCM-VMI_40keV were reconstructed. Attenuation and signal-to-noise ratio (SNR) of liver, pancreas, kidneys, lymph nodes, psoas muscle, aorta and portal vein were assessed ROIs-based. Contrast-to-noise ratios (CNR) of lymph nodes vs aorta/portal vein were calculated. Two readers evaluated organ/vessel contrast, lymph node delineation, image noise and overall assessability using 4-point Likert scales.

RESULTS

RCM were inferior to SCM images in all quantitative/qualitative criteria. RCM-VMI_40keV and SCM images showed similar lymph node and muscle attenuation (p = 0.83,0.17), while for all other ROIs, RCM-VMI_40keV showed higher attenuation (p ≤ 0.05). SNR was comparable between RCM-VMI_40keV and SCM images (p range: 0.23-0.99). CNR of lymph nodes was highest in RCM-VMI_40keV (p ≤ 0.05). RCM-VMI_40keV received equivalent or higher scores than SCM in all criteria except for organ contrast, overall assessability and image noise, where SCM were superior (p ≤ 0.05). However, RCM-VMI_40keV received proper or excellent scores in 88.6/94.2/95.4% of the referring cases.

CONCLUSIONS

VMI_40keV counteract contrast deterioration in CM reduced abdominal SDCT, facilitating diagnostic assessment.

ADVANCES IN KNOWLEDGE

SDCT-derived VMI_40keV provide adequate depiction of vessels, organs and lymph nodes even at notable CM reduction.

Remote Ischemic Preconditioning Reduces the Risk of Contrast-Induced Nephropathy in Patients with Moderate Renal Impairment Undergoing Percutaneous Coronary Angiography: A Meta-Analysis

BACKGROUND/AIMS

This meta-analysis evaluated the effects of remote ischemic preconditioning (RIPC) on the risk of contrast-induced nephropathy (CIN) in patients undergoing percutaneous coronary intervention/coronary angiography (PCI/CA).

METHODS

PubMed, Embase, and the Cochrane Central Register of Controlled Trials databases were searched for randomized controlled trials (RCTs) that assessed the effect of RIPC on CIN in patients undergoing PCI/CA. The main outcomes of interest were the incidence of CIN 48-72 h after CA, the levels of serum creatinine, cystatin C, neutrophil gelatinase-associated lipocalin, and estimated glomerular filtration rate (eGFR), mortality, and requirement of hemodialysis and rehospitalization. The analysis was conducted using the random-effect model due to the expected heterogeneity among different studies.

RESULTS

In total, 16 trials covering 2,048 patients were identified. By assessing the methodological quality of the included studies through the Coch-rane risk of bias, we found that of the 16 RCTs, 3 had a low risk of bias, 6 a high, and 7 an unclear risk. The application of RIPC decreased the incidence of CIN (relative risk, RR, 0.50, 95% confidence interval, CI, 0.39-0.65; p < 0.001). Subgroup analyses showed that RIPC decreased the incidence of CIN in patients with eGFR <60 mL/min/1.73 m2 (RR 0.53, 95% CI 0.38-0.75; p < 0.001) but not in patients with eGRF ≥60 mL/min/1.73 m2 (RR 0.82, 95% CI 0.35-1.94; p = 0.66) at baseline. Furthermore, the increase in serum creatinine was significantly lower in patients with RIPC compared to control patients (standardized mean difference -1.41, 95% CI -2.46 to -0.35; p = 0.009).

CONCLUSIONS

Based on 16 RCTs, this meta-analysis shows that RIPC can reduce the risk of CIN in patients with moderate renal impairment undergoing PCI/CA. However, this needs to be confirmed by further high-quality evidence.

Risk for Contrast-Induced Nephropathy in Elderly Trauma Patients

The objective of this study was to determine if elderly trauma patients are at risk for contrast-induced nephropathy (CIN). A retrospective study was conducted identifying 362 patients 65 years and older in our Level I trauma center who received computerized tomography (CT) scans with intravenous contrast. CIN was defined as a 25 per cent increase in serum creatinine levels or a 0.5 mg/dL increase above baseline after CT. History of diabetes mellitus, hospital length of stay, intensive care unit length of stay, Injury Severity Score (ISS), and age were recorded. Eighteen per cent (21 of 118) of the patients had a peak in creatinine, 12 per cent (14 of 118) peaked and returned to baseline, and 6 per cent (7 of 118) peaked and stayed high. Pre-CT elevated creatinine, diabetes mellitus, increased hospital length of stay, ISS, and age show little association to CIN. The data suggest that CIN in elderly trauma patients is rare, regardless of history of diabetes mellitus, age, creatinine, high ISS, or result in higher length of stay. Therefore, there is little justification for the delay in diagnosis to assess a patient's renal susceptibility.

Nanoparticle contrast agents for X-ray imaging applications

X-ray imaging is the most widely used diagnostic imaging method in modern medicine and several advanced forms of this technology have recently emerged. Iodinated molecules and barium sulfate suspensions are clinically approved X-ray contrast agents and are widely used. However, these existing contrast agents provide limited information, are suboptimal for new X-ray imaging techniques and are developing safety concerns. Thus, over the past 15 years, there has been a rapid growth in the development of nanoparticles as X-ray contrast agents. Nanoparticles have several desirable features such as high contrast payloads, the potential for long circulation times, and tunable physicochemical properties. Nanoparticles have also been used in a range of biomedical applications such as disease treatment, targeted imaging, and cell tracking. In this review, we discuss the principles behind X-ray contrast generation and introduce new types of X-ray imaging modalities, as well as potential elements and chemical compositions that are suitable for novel contrast agent development. We focus on the progress in nanoparticle X-ray contrast agents developed to be renally clearable, long circulating, theranostic, targeted, or for cell tracking. We feature agents that are used in conjunction with the newly developed multi-energy computed tomography and mammographic imaging technologies. Finally, we offer perspectives on current limitations and emerging research topics as well as expectations for the future development of the field. This article is categorized under: Diagnostic Tools > in vivo Nanodiagnostics and Imaging Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Protective Effect of N-Acetylcysteine Pretreatment on Acute Kidney Injury in Septic Rats

BACKGROUND

The aim of this study is to investigate the protective effect of N-acetylcysteine (NAC) pretreatment on acute kidney injury in septic rats.

METHODS

We constructed a septic rat model by cecal ligation and perforation (CLP) and assessed kidney tissue pathologic damage, renal function changes, and inflammatory factor levels. Meanwhile, we also assessed oxide and antioxidant enzyme levels in kidney tissues, observed apoptosis of kidney tissues, and evaluated mitochondrial membrane activity in renal cortical cells.

RESULTS

Pretreatment of NAC significantly alleviated pathologic damage of kidney tissues in septic rats; decreased the levels of serum creatinine, blood urea nitrogen, plasma neutrophil gelatinase-associated lipocalin, and kidney injury molecule-1; and reduced the expression of tumor necrosis factor a, interleukin [IL]-1β, IL-6, and IL-8. Furthermore, NAC pretreatment reduced the level of protein-nitrotyrosine adducts and malondialdehyde in CLP-induced kidney tissues, while elevated the levels of superoxide dismutase, glutathione peroxidase, and catalase. Moreover, pretreatment of NAC reduced the number of apoptosis in kidney tissues induced by CLP, decreased the mRNA levels of caspase-3, caspase-9, cytochrome c, and poly ADP-ribose polymerase, and increased mitochondrial membrane activity in renal cortical cells (complex I/II/III/IV).

CONCLUSIONS

NAC pretreatment has protective effects on acute kidney injury induced by CLP, and its mechanism is closely related to anti-inflammatory, antioxidation, antiapoptosis, and regulation of mitochondrial function.

Impact of pretreatment with carnitine and tadalafil on contrast-induced nephropathy in CKD patients

Objective: The present study assesses whether phosphodiesterase type 5 (PDE-5) inhibitor or carnitine exert nephroprotective effects against clinical contrast-induced nephropathy (CIN).

Materials and Methods: The present study consisted of three groups of CKD patients. The first group was control group, who were treated with N-acetyl-L-cysteine 1 day before and on the day of radiocontrast administration. The second one was carnitine group, where the patients were infused with carnitine over 10 min 2 h prior to the radiocontrast administration and 24 h post CT. The third one was PDE-5 inhibitor group, where patients were given tadalafil 2 h prior to the administration of the radiocontrast and in the subsequent day. Urine and blood samples were collected before and at the following time sequence: 2, 6, 12, 24, 48, and 120 h after the contrast administration, for creatinine and NGAL determination.

Results: Pretreated with N-acetyl-L-cysteine prior to administration of contrast media (CM) to CKD patients caused a significant increase in urinary but not of plasma neutrophil gelatinase-associated lipocalin (NGAL) and serum creatinine (SCr). In contrast, pretreatment with carnitine prevented the increase in urinary NGAL and reduced SCr below basal levels. Similarly, tadalafil administration diminished the elevation of CM-induced urinary NGAL.

Conclusions: These results indicate that carnitine and PDE-5 inhibitors may comprise potential therapeutic maneuvers for CIN.

Risk of acute kidney injury after contrast-enhanced computed tomography in emergency department

Background:

Despite its risks associated with renal injury, intravenous contrast media increases diagnostic efficacy and hence the chance of early diagnosis and treatment, which leaves clinicians in a dilemma regarding its use in emergency settings.

Objective:

The aim of this study was to determine the risk and predictors of contrast-induced acute kidney injury following intravenous contrast media administration for computed tomography in the emergency department.

Methods:

All patients aged 18 years and older who had a basal creatinine measurement within the last 8 h before contrast-enhanced computed tomography and a second creatinine measurement within 48–72 h after computed tomography scan between 1 January 2015 and 31 December 2017 were included in the study. Characteristics of patients with and without contrast-induced acute kidney injury development were compared. Multivariate regression analysis was used to assess the predictors for contrast-induced acute kidney injury.

Results:

A total of 631 patients were included in the final statistical analysis. After contrast media administration, contrast-induced acute kidney injury developed in 4.9% ( n = 31) of the patients. When the characteristics of patients are compared according to the development of contrast-induced acute kidney injury, significant differences were detected for age, initial creatinine, initial estimated glomerular filtration rate, and all acute illness severity indicators (hypotension, anemia, hypoalbuminemia, and need for intensive care unit admission). A multivariate logistic regression analysis was performed. The need for intensive care unit admission (odds ratio: 6.413 (95% confidence interval: 1.709–24.074)) and hypotension (odds ratio: 5.575 (95% confidence interval: 1.624–19.133)) were the main factors for contrast-induced acute kidney injury development.

Conclusion:

Our study results revealed that hypotension, need for intensive care, and advanced age were associated with acute kidney injury in patients receiving contrast media. Therefore, we believe that to perform contrast-enhanced computed tomography in emergency department should not be decided only by checking for renal function tests and that these predictors should be taken into consideration.

Protective Effects of Amlodipine Pretreatment on Contrast-Induced Acute Kidney Injury And Overall Survival In Hypertensive Patients

Backgroud

Contrast-induced acute kidney injury (CI-AKI) is the most common adverse reaction caused by contrast media, which has been reported to prolong hospitalization and increase mortality and morbidity. The hypertensive population has proved susceptible to CI-AKI. Unfortunately, no therapeutic has been shown to prevent and cure CI-AKI effectively. A few studies have shown the protection of amlodipine on renal function, but the relationship between amlodipine and CI-AKI in hypertensive group is unknown, we aimed to study the effects of amlodipine on CI-AKI and overall survival in a large Chinese hypertensive cohort.

Methods

A retrospective, matched, cohort study was conducted among adults hospitalized at the Third Xiangya Hospital of Central South University from October 2007 to May 2017. CI-AKI was the primary end point of the trial, time-related all-cause mortality (including in-hospital) and length of hospital stay were the secondary end points. Propensity Score Matching was used to reduce the effect of selection bias and potential confounding.

Results

868 patients with and 1,798 ones without amlodipine before contrast administration were included. The incidence of CI-AKI was 10.50%. The unadjusted, adjusted, and propensity‐score matched incidence of CI-AKI were lower in patients treated with amlodipine (OR, 0.650; P = 0 .003; OR, 0.577; P = 0.007; OR, 0.687; P = 0.015, respectively), and the same results were found in the subgroups of diabetes, chronic kidney disease (CKD), non-CKD, low-osmolar, and elderly. Moreover, amlodipine reduced hospital stay, whether matched or not (7.08 ± 7.28 vs 7.77 ± 7.82, P = 0.027, before matching; vs 7.81 ± 7.58, P = 0.040, after matching). 1,046 patients finished follow-up including 343 amlodipine users and 703 non-users. The overall mortality was significantly lower among amlodipine users (10.79%) than controls (16.07%), the significant difference was found in survival between them (P = 0.024, log-rank test), amlodipine was associated with longer overall survival [HR, 0.623; 95% CI (0.430–0.908), P = 0.014].

Conclusion

In conclusion, we first found amlodipine treatment before contrast exposure played a role in protecting hypertensive patients from CI-AKI and prolonging survival.

The impact of percutaneous coronary intervention using the novel dynamic coronary roadmap system

The dynamic coronary roadmap (DCR) is a novel technology that creates a dynamic, motion-compensated, real-time overlay of the coronary arteries on a fluoroscopic image. Whether the DCR reduces contrast volume and enables safe and effective treatment was examined. A total of 146 patients undergoing percutaneous coronary intervention (PCI) from June 2017 to September 2017 in our hospital were retrospectively evaluated. Chronic total occlusion lesions, acute coronary syndrome, and hemodialysis patients were excluded. Patients were divided into the control group (PCI without DCR, 92 patients, 103 lesions) and the DCR group (38 patients, 43 lesions). The primary endpoint was contrast medium volume, and secondary endpoints were radiation dose, fluoroscopy time, and clinical success rate. There was no significant difference in the success rate (100% vs. 100%, P = 1.000) between the groups. Fluoroscopy time (16.3 ± 11.2 min. vs. 11.4 ± 5.5 min, P = 0.007) and contrast medium volume (152.1 ± 73.0 ml vs. 118.8 ± 49.7 ml, P = 0.006) were significantly lower in the DCR group than in the control group. DCR use during PCI was associated with a significant reduction in contrast volume and fluoroscopy time compared to a control group despite similar clinical, lesion, and procedural characteristics.

Acute hyperglycemia and contrast-induced nephropathy in patients with non-ST elevation myocardial infarction

Acute hyperglycemia and contrast-induced nephropathy (CIN) are frequently observed in non-ST elevation myocardial infarction (NSTEMI) patients undergoing percutaneous coronary intervention (PCI), and both are associated with an increased mortality rate. We investigated the possible association between acute hyperglycemia and CIN in patients with NSTEMI undergoing PCI.

Materials and methods

We retrospectively enrolled 281(149, 53% men) NSTEMI patients undergoing PCI. For each patient, plasma glucose levels were secreened at hospital admission. Acute hyperglycemia was defined as glucose levels > 198 mg/dl. CIN was defined as an increase in serum creatinine 25% or 0.5 mg/dl from baseline in the first 48-72 hours.

Results

Overall, 44 (15.7%) patients had acute hyperglycemia. Patients with acute hyperglycemia had higher incidence of CIN than those without acute hyperglycemia (29.5 vs 5.1%, P < 0.001). Also, in-hospital mortality, length of hospital stay, major bleeding, requirement of mechanical ventilation and dialysis were observed significantly higher in patients with hyperglycemia. Patients were then reallocated to two groups according to the presence or absence of CIN. Overall, 25 cases (8.9%) of CIN were diagnosed. Diabetes mellitus, weight, age, glucose level and estimated glomerular filtration rate (eGFR) were detected as independent risk factors of CIN. Additionally, admission glucose levels were significantly correlated with creatinine levels after PCI, eGFR and contrast volume/eGFR ratio.

Conclusion

In NSTEMI patients undergoing primary PCI, acute hyperglycemia may be associated with an increased risk for CIN and in-hospital mortality and morbidity.

Validation of pre-operative risk scores of contrast-induced acute kidney injury in a Chinese cohort

Background

Pre-operative risk scores are more valuable than post-procedure risk scores because of lacking effective treatment for contrast-induced acute kidney injury (CI-AKI). A number of pre-operative risk scores have been developed, but due to lack of effective external validation, most of them are also difficult to apply accurately in clinical practice. It is necessary to review and validate the published pre-operative risk scores for CI-AKI.

Materials and methods

We systematically searched PubMed and EMBASE databases for studies of CI-AKI pre-operative risk scores and assessed their calibration and discriminatory in a cohort of 2669 patients undergoing coronary angiography or percutaneous coronary intervention (PCI) from September 2007 to July 2017. The definitions of CI-AKI may affect the validation results, so three definition were included in this study, CI-AKI broad1 was defined as an increase in serum creatinine (Scr) of 44.2 μmol/L or 25%; CI-AKI broad2, an increase in Scr of 44.2 μmol/L or 50%; and CI-AKI-narrow, an increase in Scr of 44.2 μmol/L. The calibration of the model was assessed with the Hosmer-Lemeshow test and the discriminatory capacity was identified by C-statistic.

Results

Of the 8 pre-operative risk scores for CI-AKI identified, 7 were single-center study and only 1 was based on multi-center study. In addition, 7 of the scores were just validated internally and only Chen score was externally validated. In the validation cohort of 2669 patients, the incidence of CI-AKI ranged from 3.0%(Liu) to 16.4%(Chen) for these scores. Furthermore, the incidence of CI-AKI was 6.59% (178) for CI-AKI broad1, 1.44% (39) for CI-AKI broad2, and 0.67% (18) for CI-AKI-narrow. For CI-AKI broads, C-statistics varied from 0.44 to 0.57. For CI-AKI-narrow, the Maioli score had the best discrimination and calibration, what’s more, the C-statistics of Maioli, Chen, Liu and Ghani was ≥0.7.

Conclusion

Most pre-operative risk scores were established based on single-center studies and most of them lacked external validation. For CI-AKI broads, the prediction accuracy of all risk scores was low. The Maioli score had the best discrimination and calibration, when using the CI-AKI-narrow definition.

Updated guidelines for intravenous contrast use for CT and MRI

Intravenous (IV) contrast material is used extensively for CT and MRI scans done in emergency departments (ED). Its use is essential to make many critical diagnoses in ED patients. While adverse reactions can occur, newer research has added to our knowledge of IV contrast media tolerance and safety leading to improved and more liberal guidelines for intravenous contrast use. The updated information described in this review article indicates how intravenous contrast can be used safely in more patients, more expeditiously and with fewer precautions than with prior guidelines. This review article explains the basis for the new recommendations for intravenous contrast material use and describes indicated precautions and preparations to avoid adverse reactions for iodinated agents used for CT and gadolinium agents for MRI.

Computed Tomography Angiography Combined With Knowledge-Based Iterative Algorithm for Transcatheter Aortic Valve Implantation Planning: Image Quality and Radiation Dose Exposure With Low-kV and Low-Contrast-Medium Protocol

OBJECTIVE

To evaluate image quality and radiation dose exposure of low-kV setting and low-volume contrast medium (CM) computed tomography angiography (CTA) protocol for transcatheter aortic valve implantation (TAVI) planning in comparison with standard CTA protocol.

METHODS

Sixty-patients were examined with 256-row MDCT for TAVI planning: 32 patients (study group) were evaluated using 80-kV electrocardiogram-gated protocol with 60 mL of CM and IMR reconstruction; 28 patients underwent a standard electrocardiogram-gated CTA study (100 kV; 80 mL of CM; iDose4 reconstruction). Subjective and objective image quality was evaluated in each patient at different aortic levels. Finally, we collected radiation dose exposure data (CT dose index and dose-length product) of both groups.

RESULTS

In study protocol, significant higher mean attenuation values were achieved in all measurements compared with the standard protocol. There were no significant differences in the subjective image quality evaluation in both groups. Mean dose-length product of study group was 56% lower than in the control one (P < 0.0001).

CONCLUSION

Low-kV and low-CM volume CTA, combined with IMR, allows to correctly performing TAVI planning with high-quality images and significant radiation dose reduction compared with standard CTA protocol.

Acute kidney injury - A frequent and serious complication after primary percutaneous coronary intervention in patients with ST-segment elevation myocardial infarction

OBJECTIVES

The aim of the study was to investigate the incidence, risk factors and long-term prognosis of acute kidney injury (AKI) in patients with ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (primary PCI).

METHOD

A large-scale, retrospective cohort study based on procedure-related variables, biochemical and mortality data collected between 2009 and 2014 at Rigshospitalet, Copenhagen, Denmark. AKI was defined as an increase in serum creatinine of 25% during the first 72 hours after the index procedure.

RESULTS

A total of 4239 patients were treated with primary PCI of whom 4002 had available creatinine measurements allowing for assessment of AKI and inclusion in this study. The mean creatinine value upon presentation for all patients was 84 μmol/l (standard deviation (SD) ±40) and 97 μmol/l (SD ±53) at peak. AKI occurred in a total of 765 (19.1%) patients. Independent risk factors for the occurrence of AKI were age, time from symptom onset to procedure, peak value of troponin-T, female sex and the contrast volume to eGFR ratio. In a multivariable adjusted analysis AKI was independently associated with a higher mortality rate at 5 years follow-up (hazard ratio 1.39 [95%-confidence interval 1.03-1.88]).

CONCLUSION

In STEMI patients treated with primary PCI one in five experiences acute kidney injury, which was associated with a substantial increase in both short- and long-term mortality.

Standardisation of Technique and Volume of Iodinated Contrast Administration During Infrainguinal Angioplasty

BACKGROUND

Acute Kidney injury is recognised to occur after administration of iodinated contrast during endovascular interventions for peripheral arterial disease. There are no standardised protocols for contrast delivery during infrainguinal angiography.

OBJECTIVE

The objective of this paper is to review published practice regarding the technique of conventional infrainguinal angiography and intervention, and describe a standard set of subtraction views, injection rates and contrast volumes for infrainguinal angioplasty.

METHODS

Database searches and review of papers containing (Angioplasty or Angiography) and ("lower limb" or peripheral or infrainguinal) and (method or technique or guidelines or protocol) was performed and defined procedures assessed.

RESULTS

A small number of papers provided specific technical details relating to contrast volumes and angiography views. There was considerable variation from authors who have described the contrast volumes used for lower limb angiography. We describe our simple and consistent method. The precise pathophysiology of contrast related nephropathy is under scrutiny. There is interest in new technology to minimise contrast induced kidney injury.

CONCLUSION

Few publications specify iodinated contrast doses, injection volumes or imaging views for infrainguinal arteriography. Standard infrainguinal angioplasty can be performed with conventional equipment using relatively small volumes of contrast by following a systematic technique.

Effects of ECE-1b rs213045 and rs2038089 polymorphisms on the development of contrast-induced acute kidney injury in patients with acute coronary syndrome

OBJECTIVE

Endothelin-1 (ET-1) promotes the progression and induction of sclerotic renal changes in end-stage kidney disease. Membrane-bound endothelin-converting enzyme 1 (ECE-1) is involved in the production of ET-1. The aim of this study was to assess the effects of ECE-1b rs213045 and rs2038089 polymorphisms, which have been shown to be involved in the development of atherosclerosis, hypertension, and nephropathy, on the development of contrast-induced acute kidney injury (CI-AKI) in patients with acute coronary syndrome.

METHODS

Our study included 38 patients with CI-AKI (CI-AKI[+]) and 55 patients without CI-AKI (CI-AKI[-]) who had coronary syndrome. The ECE-1b polymorphisms rs213045 and rs2038089 were assessed using real-time PCR. Serum ET-1 levels were measured by ELISA.

RESULTS

The distributions of ECE-1b rs213045 and rs2038089 polymorphisms were similar between the two groups. Additionally, the serum ET-1 level did not different between the groups and was not associated with the ECE-1b polymorphisms. Peri-procedural low systolic blood pressure (SBP) was identified as a risk factor for CI-AKI development.

CONCLUSION

Our findings indicate that ECE-1b rs213045 and rs2038089 polymorphisms are not associated with CI-AKI development and that peri-procedural low SBP is a risk factor for CI-AKI. However, variations in ECE-1b rs2038089 may contribute to the development of CI-AKI.

Renally Excretable and Size-Tunable Silver Sulfide Nanoparticles for Dual-Energy Mammography or Computed Tomography

Significant effort has been focused on developing renally-clearable nanoparticle agents since efficient renal clearance is important for eventual clinical translation. Silver sulfide nanoparticles (Ag₂S-NP) have recently been identified as contrast agents for dual energy mammography, computed tomography (CT) and fluorescence imaging and probes for drug delivery and photothermal therapy with good biocompatibility. However, most Ag₂S-NP reported to date are not renally excretable and are observed in vivo to accumulate and remain in the reticuloendothelial system (RES) organs, i.e. liver and spleen, for a long time, which could negatively impact their likelihood for translation. Herein, we present renally-clearable, 3.1 nm Ag₂S-NP with 85% of the injected dose (ID) being excreted within 24 hours of intravenous injection, which is amongst the best clearance of similarly sized nanoparticles reported thus far (mostly between 20-75% of ID). The urinary excretion and low RES accumulation of these nanoparticles in mice were indicated by in vivo CT imaging and biodistribution analysis. In summary, these ultrasmall Ag₂S-NP can be effectively eliminated via urine and have high translational potential for various biomedical applications.

CHA2DS2-VASC Score Predicts Risk of Contrast-Induced Nephropathy in Non-ST Elevation Myocardial Infarction Patients Undergoing Percutaneous Coronary Interventions

BACKROUND

The CHA2DS2-VASC score, used for embolic risk stratification in atrial fibrillation, has been reported recently to predict adverse clinical outcomes in patients with coronary artery disease. We investigated the correlation between the CHA2DS2-VASC score and contrast-induced nephropathy (CIN) in patients with non-ST elevation myocardial infarction (NSTEMI) who underwent percutaneous coronary intervention (PCI).

METHODS

We retrospectively enrolled 363 (191; 52.6% men) NSTEMI patients undergoing PCI. The CHA2 DS2-VASC score was calculated for each patient, and the study population was divided into 2 groups: CHA2DS2-VASC score <2 group (low score; n = 259, 71.3%) and CHA2DS2-VASC score ≥2 group (high score; n = 104, 28.6%). Patients were then reallocated to 2 groups according to the presence or absence of CIN. CIN was defined as a rise in serum creatinine >0.5 mg/dL or >25% increase in baseline within 72 h after PCI.

RESULTS

Overall, 56 cases (15.4%) of CIN were diagnosed. When patients with a CHA2DS2-VASC score of <2 were compared with those with a CHA2DS2-VASC score of ≥2, patients with a high score had a higher frequency of CIN (33) 31.7% versus (23) 8.9%; p < 0.001. Also patients with CIN had higher CHADS2 VASC score (3.94 ± 1.13 vs. 1.68 ± 0.46, p < 0.001). Additionally, in-hospital mortality, length of hospital stay, major bleeding, requirement of mechanical ventilation, and dialysis were observed significantly higher in patients with CHA2DS2-VASC score of ≥2 (p = 0.001, p = 0.002, p = 0.006, p = 0.001, p = 0.001, respectively). In receiver operating characteristic curve analysis, the area under the curve for predicting CIN was 0.702 (p < 0.001, 95% CI 0.617-0.787) and cutoff value was 2.5 (sensitivity 58.9%, specificity 76.9%) for the number of CHA2DS2-VASC score.

CONCLUSION

In NSTEMI patients undergoing PCI, CHADS2 VASC score is associated with an increased risk for CIN and in-hospital morbidity and mortality.

Adenosine antagonists for prevention of contrast-induced nephropathy: A meta-analysis of randomized controlled trials with trial sequential analysis

Contrast-induced nephropathy (CIN) is caused by intravascular administration of contrast agent. The efficacy of adenosine antagonists (AAs) in preventing CIN remains controversial, and its elucidation was the objective of the present meta-analysis. A trial sequential analysis (TSA) to assess the reliability of the pooled results was also performed. The Medline, Embase, Web of Science and Cochrane databases were searched to retrieve all published randomized controlled trials (RCTs) comparing AAs with controls in preventing CIN. Heterogeneity, publication bias and quality of studies were assessed. Sensitivity, cumulative and subgroup analyses were also performed. The risk of random errors was evaluated by TSA. A total of 17 trials with 1,483 subjects were included. Pooled results indicated that AAs significantly reduced the incidence of CIN [risk ratio, 0.53; 95% confidence interval (CI), 0.29-0.95; P=0.034] and the serum creatinine (SCr) level after contrast media (CM) administration (standardized mean difference, -0.24; 95% CI, -0.44 to -0.04; P=0.019). Meta-regression did not identify any significant source of heterogeneity. In the subgroup analyses, AAs tended to exhibit a greater prevention efficacy in trials with sample sizes of ≥70, baseline SCr of <1.5 mg/dl and low study quality. TSA on the incidence of CIN indicated that the required information size determined as n=1,778 was not reached, and that the cumulative Z-curve did not cross the TSA boundary. In conclusion, the present meta-analysis of data from current RCTs suggested that AAs reduce the incidence of CIN and the SCr levels after CM administration. However, TSA showed that the risk of having a false-positive result was greater than 5% in the meta-analysis of the incidence of CIN, indicating that more evidence is required to ensure the benefit of AAs in preventing CIN.

The association between post-procedural oral hydration and risk of contrast-induced acute kidney injury among ST-elevation myocardial infarction patients undergoing primary percutaneous coronary intervention

BACKGROUND

Oral hydration with water may be inexpensive and effective in the prevention of contrast-induced acute kidney injury (CI-AKI), but its efficacy among ST-elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PCI) remains unknown.

METHODS

This was a prospective, single-center, observational study. We consecutively enrolled 308 STEMI patients undergoing primary PCI. All patients drank unrestricted amounts of fluids freely, whose volume was recorded until 24 hours following primary PCI. Oral hydration volume/weight ratios (OHV/W) were calculated. Adequate oral hydration was defined as a ratio over 12 mL/kg within 24 hours after primary PCI. The primary outcome measure was CI-AKI, defined as a 25% or 0.5 mg/dL increase in serum creatinine from baseline during the first 48-72 hours post-procedure. The association between adequate post-procedural oral hydration and CI-AKI was assessed using multivariable logistic analysis.

RESULTS

Post-procedural prophylactic oral hydration was implemented in 90.91% (280/308) of STEMI patients undergoing primary PCI. There were no differences in the sex, age, weight, index blood pressure, LVEF, anemia, diabetes mellitus, contrast volume used during the coronary procedures between groups (P>0.05). The incidence of CI-AKI was much higher in the inadequate oral hydration group (<12 mL/kg) than the adequate group (≥12 mL/kg) (53.57% vs. 21.79%, P=0.0002). Multivariate logistic regression showed adequate oral hydration (≥12 mL/kg) was the independent protective factor associated with CI-AKI (OR =0.349, 95% CI: 0.147-0.828, P=0.0170), after adjusting confounders, including age, female gender, baseline serum creatinine, diabetes mellitus, use of diuretics, congestive heart failure and intravenous hydration volume.

CONCLUSIONS

Our study determined the association of post-procedural adequate oral hydration on CI-AKI following primary PCI, which was a potential strategy for CI-AKI prevention among patients with STEMI at very high risk.

Computed Tomography Postprocessing for Abdominal Aortic Aneurysm Lumen Recognition in Unenhanced Examinations

INTRODUCTION

Contrast medium (CM) use in computed tomography (CT) is limited by nephrotoxicity and possible allergic reactions. The purpose of this study is to introduce a tool for the diagnosis of abdominal aortic aneurysms (AAAs) by avoiding the use of CM.

METHODS

With and without CM CTs of patients with AAA were evaluated. A mathematical algorithm was implemented to allow visualization of the inner aortic lumen in the series without CM. The first step of the algorithm consisted in manually highlighting a squared region of interest (ROI) close to the target aortic area. The rest of the algorithm is completely automated and performs the following flow of operations: The "Kantorovich" algorithm is applied to the ROI for image enhancement. Then, a wavelet decomposition method is applied to identify the different frequency components of the image. Exploiting the wavelet decomposition, the system selects the low-frequency components of the image, corresponding to the major structures. Thresholding method, based on the analysis of the gray-level histogram, is then performed to extract the contours of the vessel. At this point, the extraction of the pervious area is completed. Final images were compared with the contrast enhanced scans, valued as gold standard. To validate the algorithm, an analysis of the results has been performed considering the following types of error: E_n = #m/#ROI ΔA = |1-(#CM/#CEX)| (#_m = number of misclassified pixels; #_ROI = number of pixels in the ROI; #_CM = number of pixels belonging to the CM; #CEX = extracted areas). E_n provided a measure on the pixels wrongly classified, and Δ_A the difference of extracted areas.

RESULTS

The algorithm was applied to 233 CT images. Extracted images were compared with the ones with CM. Mean values of the numerical errors ranged from 0.12 to 0.17 for E_n and 0.11 to 0.35 for Δ_A. For all the 233 CT images in the analyzed sequences, the mean error was 0.14 (E_n) and 0.28 (ΔA).

CONCLUSIONS

The developed mathematical algorithm allows to detect the position of the vessel lumen and to extract its contours with a good accuracy. Our experience shows encouraging results and suggests a possible future clinical application to reduce CT CM use.