Current concepts in contrast media-induced nephropathy

Contrast induced nephropathy in women with infertility undergoing hysterosalpingography

BACKGROUND

Contrast-induced nephropathy (CIN) defined as an acute kidney injury following the administration of iodinated contrast medium (CM). Hysterosalpingography (HSG) is a radiologic procedure used to investigate the shape and structure of the uterine cavity and the patency of the fallopian tubes in the evaluation of infertility. To date, there have been no reports evaluating the development of CIN after HSG procedure. Therefore, we investigated whether CIN development occurs in infertile women who underwent HSG and its relationship with clinical and laboratory changes in women who underwent HSG.

METHODS

This study was undertaken in 65 women who had infertility evaluation, uterine anomalies and/or tubal blockages. CIN was defined as a 25% relative increase, or a 0.5 mg/dL (44 µmol/L) absolute increase, in serum baseline creatinine (SCr) within 72 h of contrast exposure in the absence of alternative conditions. Hysterosalpingography (HSG) was performed using 5-20 ml of contrast medium. All patients performed routine laboratory tests including assessment of serum creatinine and urea and estimated glomerular filtration rates before and 2-3 day after HSG. Statistical analysis was performed with MedCalc Statistical Software Program v22.023 (Ostend, Belgium) program.

RESULTS

The mean ages of participants were 29.5 years and mean BMI were 26.2 kg/m2. The rate of CIN was 12.3% and the severe nephropathy was 1.5% in our study population. The baseline SCr level was 0.59 ± 0.06 mg/dL in women with CIN and 0.67 ± 0.11 mg/dL in women without CIN. The baseline SCr level was significantly lower in CIN group that non-CIN group (p = 0.0309). The SCr level significantly higher in CIN group than non-CIN group 48-72 h after HSG (p = 0.0005). In the multivariate logistic regression analysis, the baseline SCr was found an independent risk factor for the prediction of CIN in women who underwent HSG.

CONCLUSION

The HSG procedure is generally a safe method, but the iodine-containing contrast material used in HSG may be associated with temporary adverse effects on kidney function.

Patients with Different Stages of Chronic Kidney Disease Undergoing Intravenous Contrast-Enhanced Computed Tomography-The Incidence of Contrast-Associated Acute Kidney Injury

Introduction: Iodinated contrast medium (CM) is the third most common cause of acute kidney injury (AKI). However, the association is poorly known between the definitions of AKI between different stages of chronic kidney disease after intravenous CM administration. Methods: The dataset, covering a period of ~15 years (1 June 2008 to 31 March 2015), consisted of 20,018 non-dialytic adult patients who had received intravenous injections of non-ionic iso-osmolar CM, iodixanol, for enhanced computed tomography imaging. Contrast-associated AKI (CA-AKI), dialysis-required AKI, and mortality were analyzed. Results: A total of 12,271 participants were enrolled. CA-AKI increased significantly starting from stage 3A onward (p < 0.001). In summary, incidences of CA-AKI against different levels of chronic kidney disease were as follows: stage 1 (8.3%) = stage 2 (6.7%) < stage 3A (9.9%) < stage 3B (14.3%) < stage 4 (20.5%) = stage 5 (20.4%). The incidences of dialysis within 30 days were as follows: stage 1 (1%) = stage 2 (1.4%) = stage 3A (2.7%) < stage 3B (5.7%) < stage 4 (18%) < stage 5 (54.1%). The prediction of dialysis was good based on the baseline serum creatinine > 1.5 mg/dL (72.78% of sensitivity, 86.07% of specificity, 0.851 of area under curve) or baseline estimated glomerular filtration rate ≤ 38.49 mL/min/1.732 m2 (70.19% of sensitivity, 89.08% of specificity, 0.853 of area under curve). In multivariate Cox regression analysis model for CA-AKI, independent risk factors were stage 4 chronic kidney disease (p = 0.001) and shock (p = 0.001). Conclusion: Baseline serum creatinine and estimated glomerular filtration rate were good predictors for dialysis-required AKI. CA-AKI increased significantly since stage 3A chronic kidney disease. Stage 4 and 5 chronic kidney disease have the same risk for CA-AKI, but stage 5 chronic kidney disease has markedly higher risk for dialysis.

Findings on intraprocedural non-contrast computed tomographic imaging following hepatic artery embolization are associated with development of contrast-induced nephropathy

BACKGROUND

Contrast-induced nephropathy (CIN) is a reversible form of acute kidney injury that occurs within 48-72 h of exposure to intravascular contrast material. CIN is the third leading cause of hospital-acquired acute kidney injury and accounts for 12% of such cases. Risk factors for CIN development can be divided into patient- and procedure-related. The former includes pre-existing chronic renal insufficiency and diabetes mellitus. The latter includes high contrast volume and repeated exposure over 72 h. The incidence of CIN is relatively low (up to 5%) in patients with intact renal function. However, in patients with known chronic renal insufficiency, the incidence can reach up to 27%.

AIM

To examine the association between renal enhancement pattern on non-contrast enhanced computed tomographic (CT) images obtained immediately following hepatic artery embolization with development of CIN.

METHODS

Retrospective review of all patients who underwent hepatic artery embolization between 01/2010 and 01/2011 (n = 162) was performed. Patients without intraprocedural CT imaging (n = 51), combined embolization/ablation (n = 6) and those with chronic kidney disease (n = 21) were excluded. The study group comprised of 84 patients with 106 procedures. CIN was defined as 25% increase above baseline serum creatinine or absolute increase ≥ 0.5 mg/dL within 72 h post-embolization. Post-embolization CT was reviewed for renal enhancement patterns and presence of renal artery calcifications. The association between non-contrast CT findings and CIN development was examined by Fisher’s Exact Test.

RESULTS

CIN occurred in 11/106 (10.3%) procedures (Group A, n = 10). The renal enhancement pattern in patients who did not experience CIN (Group B, n = 74 with 95/106 procedures) was late excretory in 93/95 (98%) and early excretory (EE) in 2/95 (2%). However, in Group A, there was a significantly higher rate of EE pattern (6/11, 55%) compared to late excretory pattern (5/11) (P < 0.001). A significantly higher percentage of patients that developed CIN had renal artery calcifications (6/11 vs 20/95, 55% vs 21%, P = 0.02).

CONCLUSION

A hyperdense renal parenchyma relative to surrounding skeletal muscle (EE pattern) and presence of renal artery calcifications on immediate post-HAE non-contrast CT images in patients with low risk for CIN are independently associated with CIN development.

Acute Renal Failure/Acute Kidney Injury (AKI) Associated with Endovascular Procedures

AKI is one of the most common yet underdiagnosed postoperative complications that can occur after any type of surgery. Contrast-induced nephropathy (CIN) is still poorly defined and due to a wide range of confounding individual variables, its risk is difficult to determine. CIN mainly affects patients with underlying chronic kidney disease, diabetes, sepsis, heart failure, acute coronary syndrome and cardiogenic shock. Further research is necessary to better understand pathophysiology of contrast-induced AKI and consequent implementation of effective prevention and therapeutic strategies. Although many therapies have been tested to avoid CIN, the only potent preventative strategy involves aggressive fluid administration and reduction of contrast volume. Regardless of surgical technique—open or endovascular—perioperative AKI is associated with significant morbidity, mortality and cost. Endovascular procedures always require administration of a contrast media, which may cause acute tubular necrosis or renal vascular embolization leading to renal ischemia and as a consequence, contribute to increased number of post-operative AKIs.

Proenkephalin for the early detection of acute kidney injury in hospitalized patients with chronic kidney disease

BACKGROUND

The early detection of acute kidney injury (AKI) in patients with chronic kidney disease (CKD) is an unmet clinical need. Proenkephalin (PENK) might improve the early detection of AKI.

METHODS

One hundred and eleven hospitalized CKD patients undergoing radiographic contrast procedures were enrolled. PENK was measured in a blinded fashion at baseline (before contrast media administration) and on day 1 (after contrast media administration). The potential of PENK levels to predict contrast-induced AKI was the primary endpoint.

RESULTS

Baseline creatinine and baseline PENK were similar in AKI and no-AKI patients. In AKI patients, day 1 PENK (198 pmol/L vs 121 pmol/L, P < 0.01) was significantly higher compared to no-AKI patients. The area under the curve (AUC) for the prediction of AKI by day 1 PENK was 0.79, 95% CI: 0.70-0.87, similar to serum creatinine: 0.78, 95% CI: 0.61-0.95. Delta PENK was significantly higher in AKI compared to no-AKI patients (53 pmol/L vs 1 pmol/L, P < 0.01). The AUC for the prediction of AKI by delta PENK was high (0.92, 95%CI 0.82-1.00) and remained high for creatinine-blind AKI (0.94, 95% CI: 0.87-0.97).

CONCLUSION

Delta PENK levels improve the early detection of contrast-induced AKI in CKD patients over serial creatinine sampling. Delta PENK accelerates the detection of creatinine-blind AKI by 24 hours.

Intravenous Contrast-Induced Nephropathy-The Rise and Fall of a Threatening Idea

Contrast-induced nephropathy (CIN) has been considered to be a cause of renal failure for over 50 years, but careful review of past and recent studies reveals the risks of CIN to be overestimated. Older studies frequently cited the use of high-osmolality contrast media, which have since been replaced by low-osmolality contrast media, which have lower risks for nephropathy. In addition, literature regarding CIN typically describes the incidence following cardiac angiography, whereas the risk of CIN from intravenous injection is much lower. Most of the early published literature also lacked appropriate control groups to compare to those that received iodinated contrast, and thus attributed rises in creatinine to intravenous contrast without considering normal creatinine fluctuations (frequent in patients with kidney disease) and other acute pathologic states such as hypotension or nephrotoxic drug administration. The aim of this paper is to review the literature detailing CIN risk, discuss why CIN risk is often overestimated and how withholding contrast can lead to misdiagnosis and delay in appropriate patient management.

Carotid and cerebral CT angiography using low volume of iodinated contrast material and low tube voltage

PURPOSE

To evaluate image quality of carotid computed tomography angiography (CTA) using a low voltage (80kV) and low amount of iodinated contrast material.

MATERIALS-METHODS

A total of 101 patients referred for carotid CTA were randomly assigned to receive a specific protocol. In group A patients received intravenous administration of contrast material at a dose of 1mL/kg and CTA examinations were performed at 100kV. In group B, patients received intravenous administration of contrast material at a dose of 0.5mL/kg and CTA examinations were performed at 80kV. The same nonionic iodinated contrast material containing 370mg of iodine per mL was used in both groups. Attenuation values were measured from the center of specific arterial segments using regions of interest. Attenuation values above 300HU were accepted as significant. Institutional review board approval was obtained.

RESULTS

A total of 50 patients were included in group A (38 men, 12 women; mean age, 63.56 years±13.18 [SD]) and 51 patients in group B (33 men, 18 women; mean age, 59.60 years±16.63 [SD]). A total of 1615 arterial segments (1515 common carotid artery-middle cerebral artery and 101 aortic arches) were analyzed. Venous contamination was not observed in either group. The mean attenuation values of all arterial segments in both groups were greater than 300HU. Mean arterial attenuation value in group B (499.22HU±97.25 [SD]) was significantly greater than in group A (374.36HU±73.79 [SD]) (P<0.01). Hemodynamically significant stenosis (grade III stenosis or >70%) was detected in 2 segments in group A and in 3 segments in group B, while grade IV stenosis (occlusion) was detected in 2 segments in group B. Distal common carotid artery dissection was detected in 1 patient and aortic dissection was detected in 1 patient in group B. Total dose-length product (DLP) value was significantly greater in group A (225.74mGy·cm±21.80 [SD]) than in group B (116.60mGy·cm±21.22 [SD]) (P<0.01). The mean tube current was similar in group A (2013.11mAs±195.92 [SD]) and in group B (2096.64 mAs±309.03 [SD]) (P<0.05).

CONCLUSION

Carotid and cerebral CTA examinations using 128-section CT can be successfully obtained using an imaging protocol that combines low voltage and 50% reduction in the volume of iodinated contrast material. This provides good image quality with low radiation dose.

Nephroprotective potential of carnitine against glycerol and contrast-induced kidney injury in rats through modulation of oxidative stress, proinflammatory cytokines, and apoptosis

OBJECTIVE

Contrast media (CM) are a major cause of nephropathy in high-risk patients. The aim of this study was to examine the effects of carnitine (CAR) in advanced nephrotoxicity due to CM administration in rats with glycerol-induced renal functional disorder.

METHODS

40 rats were divided randomly into five groups (n = 8): (1) healthy group; (2) glycerol only (GLY); (3) glycerol and CM (GLY + CM); (4) glycerol, CM and 200 mg kg(-1) carnitine (CAR200, Carnitene(®); Sigma-tau/Santa Farma, Istanbul, Turkey); and (5) glycerol, CM and 400 mg kg(-1) carnitine (CAR400). Kidney injury was induced with a single-dose, intramuscular injection of 10 ml kg(-1) body weight (b.w.) of GLY. CAR was administered intraperitoneally. CM (8 ml kg(-1) b.w. iohexol, Omnipaque™; Opakim Medical Products, Istanbul, Turkey) was infused via the tail vein to the rats in Groups 3-5.

RESULTS

l-carnitine administration significantly decreased serum creatinine and blood urea nitrogen levels. Superoxide dismutase and glutathione activity increased significantly in the treatment groups compared with the nephrotoxic groups. CAR400 significantly reduced malondialdehyde levels to healthy levels. In the treatment groups, tumour necrosis factor (TNF)-α, transforming growth factor 1β, interleukin 1β and caspase-3 gene expression decreased compared with the nephrotoxic groups. TNF-α and nuclear factor kappa-beta (NF-κB) protein expression increased after CM and CAR administration reduced both TNF-α and NF-κB expressions. Histopathologically, hyaline and haemorrhagic casts and necrosis in proximal tubules increased in the nephrotoxicity groups and decreased in the CAR groups.

CONCLUSION

The results reveal that l-carnitine protects the oxidant/antioxidant balance and decreases proinflammatory cytokines and apoptosis in CM-induced nephrotoxicity in rats with underlying pathology.

ADVANCES IN KNOWLEDGE

Depending on the underlying kidney pathologies, the incidence of CM-induced nephropathy (CIN) increases. Therefore, this is the best model to represent clinically observed CIN.

Comparison of combination therapy of high-dose oral N-acetylcysteine and intravenous sodium bicarbonate hydration with individual therapies in the reduction of Contrast-induced Nephropathy during Cardiac Catheterisation and Percutaneous Coronary Intervention (CONTRAST): A multi-centre, randomised, controlled trial

INTRODUCTION

N-acetylcysteine (NAC) and sodium bicarbonate (SOB) therapies may prevent contrast-induced nephropathy (CIN). However, the efficacy of using combination over individual therapies was not established, and there was no large randomised study comparing abbreviated SOB therapy with conventional sustained saline pre-hydration with oral NAC.

METHODS

In a multi-centre, open-label, randomised, controlled trial (NCT00497328), we prospectively enrolled 548 patients with at least moderate renal impairment undergoing cardiac catheterisation with or without percutaneous coronary intervention. Patients were randomly assigned to 3 groups: 1) NAC: 154 mEq/L sustained sodium chloride regime (1 mL/kg/h 12 h before, during and 6h after the procedure) with oral NAC at 1.2g bid for 3 days (n=185); 2) SOB: 154 mEq/L abbreviated SOB regime at 3 mL/kg/h 1h before the procedure, and 1 mL/kg/h during and 6h after the procedure (n=182); and 3) COM: combination of abbreviated SOB regime and oral NAC (n=181). The primary end point was incidence of CIN. The secondary end points were rise in serum creatinine, hospitalisation duration, haemodialysis, morbidity and mortality within 30 days.

RESULTS

The 3 groups had similar baseline characteristics: age 68 ± 10 years, 76% male, 48% diabetic and baseline glomerular filtration rate (GFR) 47.7 ± 13.0 mL/min. There were 41 (8.8%) patients with GFR<30. The CIN incidences were NAC 6.5%, SOB 12.8% and COM 10.6%. The COM regimen was not superior to either the NAC (relative risk (RR)=1.61, 95% confidence interval (CI): 0.76 to 3.45, p=0.225) or SOB (RR=0.83, 95% CI: 0.44 to 1.56, p=0.593) regimens. The CIN incidence was lower in the NAC group than the SOB group (adjusted odds ratio (OR)=0.40, 95% CI: 0.17 to 0.92; p=0.032). Multivariate analysis showed contrast volume (OR=1.99, 95% CI: 1.33 to 2.96, p<0.001 per 100mL), female (OR=2.47, 95% CI: 1.22 to 5.00, p=0.012) and diabetes (OR=2.03, 95% CI: 1.03 to 3.99, p=0.041) were independent risk predictors. There were no differences in the secondary outcomes among the 3 groups.

CONCLUSION

The combination regimen was not superior to individual regimens in preventing CIN in patients with baseline renal impairment. There was a trend suggesting that the 12-hour sustained sodium chloride pre-hydration regimen was more protective than the 1-hour abbreviated SOB regimen.

Use of cystatin C and serum creatinine for the diagnosis of contrast-induced nephropathy in patients undergoing contrast-enhanced computed tomography at an oncology centre

OBJECTIVE

Our aim was to assess renal function using as laboratory measurements serum creatinine and cystatin C concentrations before and after administration of low-osmolarity (nonionic) iodinated contrast medium in patients with cancer undergoing computed tomography (CT).

METHODS

This prospective study included 400 oncologic outpatients. Serum creatinine and cystatin C concentrations were measured before and 72 h after contrast administration. Glomerular filtration rates (GFRs) were estimated using serum creatinine-based [Modification of Diet in Renal Disease (MDRD) and Cockroft-Gault and cystatin C based (Larsson) equations. Exploratory data analysis was performed. The nonparametric Wilcoxon test was used to compare pre and post contrast of test results and estimated clearance. The confidence interval used in the analysis was 95%.

RESULTS

Compared with the pre-contrast values, the mean serum creatinine concentration was significantly higher and average GFRs estimated using MDRD and Cockcroft-Gault equations were significantly lower after the administration of contrast (p <0.001). It was also observed a significant increase after contrast in the concentration of Cystatin C (p = 0.015). In addition, a decrease in GFR estimated using the average Larsson (p = 0.021) was observed between time points. However, none of the patients presented clinically significant nephropathy.

CONCLUSIONS

Assessment using serum creatinine and cystatin C concentrations showed changes in renal function among patients with cancer undergoing contrast-enhanced CT examination in this study. No significant renal damage related to the use of low-osmolarity iodinated contrast medium of the type and dosage employed in this study was observed. This contrast medium is thus safe for use in patients with cancer.

Oral salt and water versus intravenous saline for the prevention of acute kidney injury following contrast-enhanced computed tomography: study protocol for a pilot randomized trial

Background

Although intravenous saline is the accepted prophylactic measure for the prevention of contrast- induced acute kidney injury, the oral route could offer an equivalent, practical, and cost saving approach. A systematic review of randomized trials that compared oral versus intravenous volume expansion for the prevention of radiocontrast-induced nephropathy in patients receiving arterial contrast reported no significant difference in the risk of contrast induced acute kidney injury between the oral and intravenous arms. Most trials for contrast nephropathy prevention have been in the setting of arterial contrast such as with cardiac catheterization, and not with venous contrast, such as computed tomography. The aim of this paper is to describe the protocol of a pilot trial comparing the effect of oral salt and water versus intravenous saline on the prevention of Acute Kidney Injury following contrast-enhanced computed tomography.

Methods

Our study is a pilot, single-centre parallel randomized controlled trial. To be included, participants must be at stage 4 of chronic kidney disease as defined by a glomerular filtration rate <30 mL/min/1.73 m², aged greater than 18 years and to undergo an outpatient contrast-enhanced computer tomography of the chest or abdomen. A total 50 patients will be randomised to receive either oral salt and water or intravenous isotonic saline. The primary outcome is feasibility, including estimates of recruitment rate, adherence to intervention and completeness of follow-up to assist in planning the definitive trial. The secondary outcome is safety and includes adverse events with oral salt and water loading as compared to intravenous isotonic saline.

Discussion

The results of this pilot trial will provide critical information to plan a definitive trial to test the efficacy of the route of volume loading regimens in prevention of acute kidney injury after contrast-enhanced CT scans.

Trial registration

The trial is registered at the US National Institutes of Health (ClinicalTrials.gov) # NCT02084771.

Development of contrast-induced acute kidney injury after elective contrast media exposure in patients with type 2 diabetes mellitus: effect of albuminuria

BACKGROUND

The influence of albuminuria and urinary pH on the development of contrast-induced acute kidney disease (CI-AKI) in patients with type 2 diabetes mellitus (T2DM) after elective coronary angiography (CAG) or percutaneous coronary intervention (PCI) is unknown.

METHODS

CI-AKI was defined as an increase in serum creatinine >26.4 µmol/L or ≥50% of baseline value within 48 hours after contrast media exposure. Demographics, traditional risk factors, clinical outcomes and CI-AKI incidence were compared between groups. Univariate analysis and multivariate logistic regression were performed to assess risk factors of CI-AKI.

RESULTS

We observed 597 patients with T2DM after CAG or PCI. Patients were divided into 3 groups based on early morning urinary albumin: negative group (urine dipstick negative, n = 483), trace group (urine dipstick trace, n = 60), and positive group (urine dipstick ≥1+, n = 54). CI-AKI occurred in 33 (5.5%) patients, including 19 (3.9%) in the negativealbuminuria group, 4 (6.7%) in the trace group, and 10 (18.5%) in the positive group (p< 0.001), respectively. After adjusting for potential confounding risk factors, positive albuminuria (OR = 3.8, 95% CI: 1.5 to 9.2, p = 0.004) and urinary pH<6 (OR = 2.4, 95% CI: 1.1 to 5.1, p = 0.020) remained significantly associated with CI-AKI.

CONCLUSION

Preprocedural albuminuria and urinary pH <6 are independent risk factors of CI-AKI in patients with T2DM undergoing elective cardiac catheterization, and may be used to identify patients at high risk of post-procedural CI-AKI.

The role of inflammation in contrast-induced nephropathy

Objective:

Global incidence of contrast-induced nephropathy (CIN) is 2–5%, but a recent Kenyan study highlighted a local incidence of 12–14% without offering an explanation for the higher incidence. This study proposes that inflammatory states confer a higher relative risk for development of CIN. Our objective was to determine the risk of developing CIN given the presence of an inflammatory state in patients in Kenya.

Methods:

Prospective cohort study of patients undergoing a contrast-enhanced CT (CECT) scan in a private university teaching hospital in Kenya and having no known risk factors for CIN. 423 patients were recruited and grouped into those without inflammation (unexposed) having serum C-reactive protein (CRP) levels ≤5 mg dl⁻¹ and those with evidence of inflammation having CRP levels >5 mg dl⁻¹. Serum creatinine (SCr) was measured before the CECT and 48 h following the CECT with CIN diagnosed by an increase of >25% in the SCr from the baseline. Relative risk was determined and multiple logistic regression analysis performed on biophysical variables and contrast volume to assess their effect on development of CIN.

Results:

Patients with high CRP levels had a relative risk of developing CIN of 2.16 compared with those with normal levels of CRP (p = 0.016). No statistically significant association was seen between biophysical variables or volume of contrast and development of CIN.

Conclusion:

Ongoing inflammation doubles the likelihood of development of CIN.

Advances in knowledge:

This study highlights the importance of inflammation as a risk factor in the development of CIN.

Contrast-induced Nephropathy

Contrast-induced nephropathy (CIN) is a serious complication of angiographic procedures resulting from the administration of contrast media (CM). It is the third most common cause of hospital acquired acute renal injury and represents about 12% of the cases. CIN is defined as an elevation of serum creatinine (Scr) of more than 25% or ≥0.5 mg/dl (44 μmol/l) from baseline within 48 h. More sensitive markers of renal injury are desired, therefore, several biomarkers of tubular injury are under evaluation. Multiple risk factors may contribute to the development of CIN; these factors are divided into patient- and procedure-related factors. Treatment of CIN is mainly supportive, consisting mainly of careful fluid and electrolyte management, although dialysis may be required in some cases. The available treatment option makes prevention the corner stone of management. This article will review the recent evidence concerning CIN incidence, diagnosis, and prevention strategies as well as its treatment and prognostic implications.

Feasibility of low-dose contrast medium high pitch CT angiography for the combined evaluation of coronary, head and neck arteries

Purpose

To evaluate the image quality and radiation dose of combined heart, head, and neck CT angiography (CTA) using prospectively electrocardiography (ECG)-triggered high-pitch spiral scan protocol, compared with single coronary CTA.

Materials and Methods

151 consecutive patients were prospectively included and randomly divided into three groups. Group 1 (n = 47) underwent combined heart, neck, and head CTA using prospectively ECG-triggered high-pitch spiral (Flash) scan protocol with a single-phase intravenous injection of iodinated contrast and saline flush; Group 2 (n = 51) underwent single coronary CTA with Flash scan protocol; and Group 3 (n = 53) underwent single coronary CTA with prospective sequence scan protocol. All patients were examined on a dual source CT (Definition FLASH). The image quality was determined for each CT study.

Results

Patients of scanning protocol Group 1, 2, and 3 showed no significant differences in age, sex, heart rates, and BMI. Evaluation of coronary artery image quality showed comparable results in the three scanning protocol groups on a per patient-based analysis. In group 1, image quality was found to be sufficient to be diagnostic in all arterial segments of carotid arteries. The mean dose-length product (DLP) for group 1 was 256.3±24.5 mGy×cm and was significantly higher in comparison with group 2 (93.4±19.9 mGy×cm; p < 0.001). However, there was no significant difference of DLP between group 1 and group 3 (254.1±69.9 mGy×cm).

Conclusions

The combined heart, neck, and head arteries scan using prospectively electrocardiography (ECG)-triggered high-pitch spiral scan protocol in 1 single examination resulted in an excellent opacification of the aorta, the carotid arteries, and the coronary arteries and provided a good image quality with low radiation dose.

Impact of mannose-binding lectin deficiency on radiocontrast-induced renal dysfunction

Contrast-induced nephropathy (CIN) is the third leading cause of acute renal failure in hospitalized patients. Endothelial dysfunction, renal medullary ischemia, and tubular toxicity are regarded as the most important factors in the pathogenesis of CIN. Mannose-binding lectin (MBL), a pattern recognition protein of the lectin pathway of complement, has been found to aggravate and mediate tissue damage during experimental renal ischemia/reperfusion (I/R) injury which was alleviated by inhibition with C1 inhibitor, a potent MBL, and lectin pathway inhibitor. In this paper, we highlight the potential role of MBL in the pathogenesis of human CIN. In experimental I/R models, MBL was previously found to induce tubular cell death independent of the complement system. In addition, after binding to vascular endothelial cells, MBL and its associated serine proteases were able to trigger a proinflammatory reaction and contribute to endothelial dysfunction. In humans, urinary MBL was increased after administration of contrast media and in individuals with CIN. Moreover, individuals with normal/high MBL levels were at increased risk to develop radiocontrast-induced renal dysfunction. Hence, MBL and the lectin pathway seem to be a promising target given that a licensed, powerful, human recombinant inhibitor exits to be added to the scarce armamentarium currently available for prophylaxis of CIN.

Relation of uric acid and contrast-induced nephropathy in patients undergoing primary percutaneous coronary intervention in the ED

OBJECTIVES

To investigate the predictive role of serum uric acid (SUA) levels measured in the emergency department (ED) to monitor contrast-induced nephropathy (CIN) and correlation with severity of nephropathy in patients undergoing primary percutaneous coronary intervention (PCI).

METHOD

The patients who were admitted to our ED and underwent primary PCI were enrolled retrospectively. Their baseline characteristics including SUA and creatinine levels in the ED and their creatinine levels 48 hours after PCI were noted. Nephropathy was graded as follows: grade 0, ΔCr ≤25% and ≤0.5 mg/dL; grade 1, ΔCr >25% but ≤0.5 mg/dL; and grade 2, ΔCr >0.5 mg/dL. A multiple logistic regression analysis was used to define the independent predictors of CIN.

RESULTS

Of a total of 744 patients, CIN was observed in 12.5% (n = 93). Serum uric acid levels were significantly higher in the CIN (+) group compared with the CIN (-) group (6.09 ± 2.01 mg/dL vs 4.89 ± 1.32 mg/dL, respectively; P < .001). Patients with grade 0 CIN had significantly lower SUA levels than did those with grades 1 and 2 (4.89 ± 1.32 mg/dL vs 5.88 ± 1.99 and 6.41 ± 2.02 mg/dL, respectively; P < .001), but there was no significant difference between grade 1 and grade 2 CIN cases in terms of SUA levels (5.88 ± 1.99 mg/dL vs 6.41 ± 2.02 mg/dL, P = .10). The cutoff value for SUA was 5.05 mg/dL for the prediction of CIN (area under the curve, 0.685; P < .001; sensitivity, 66%; specificity, 60%) in the population.

CONCLUSIONS

The SUA level is a simple independent early predictor of CIN in patients who underwent primary PCI, and early detection may help prevent the progression of CIN.

Intravenous contrast material-induced nephropathy: causal or coincident phenomenon?

PURPOSE

To determine the causal association and effect of intravenous iodinated contrast material exposure on the incidence of acute kidney injury (AKI), also known as contrast material-induced nephropathy (CIN).

MATERIALS AND METHODS

This retrospective study was approved by an institutional review board and was HIPAA compliant. Informed consent was waived. All contrast material-enhanced (contrast group) and unenhanced (noncontrast group) abdominal, pelvic, and thoracic CT scans from 2000 to 2010 were identified at a single facility. Scan recipients were sorted into low- (<1.5 mg/dL), medium- (1.5-2.0 mg/dL), and high-risk (>2.0 mg/dL) subgroups of presumed risk for CIN by using baseline serum creatinine (SCr) level. The incidence of AKI (SCr ≥ 0.5 mg/dL above baseline) was compared between contrast and noncontrast groups after propensity score adjustment by stratification, 1:1 matching, inverse weighting, and weighting by the odds methods to reduce intergroup selection bias. Counterfactual analysis was used to evaluate the causal relation between contrast material exposure and AKI by evaluating patients who underwent contrast-enhanced and unenhanced CT scans during the study period with the McNemar test.

RESULTS

A total of 157,140 scans among 53,439 unique patients associated with 1,510,001 SCr values were identified. AKI risk was not significantly different between contrast and noncontrast groups in any risk subgroup after propensity score adjustment by using reported risk factors of CIN (low risk: odds ratio [OR], 0.93; 95% confidence interval [CI]: 0.76, 1.13; P = .47; medium risk: odds ratio, 0.97; 95% CI: 0.81, 1.16; P = .76; high risk: OR, 0.91; 95% CI: 0.66, 1.24; P = .58). Counterfactual analysis revealed no significant difference in AKI incidence between enhanced and unenhanced CT scans in the same patient (McNemar test: χ(2) = 0.63, P = .43) (OR = 0.92; 95% CI: 0.75, 1.13; P = .46).

CONCLUSION

Following adjustment for presumed risk factors, the incidence of CIN was not significantly different from contrast material-independent AKI. These two phenomena were clinically indistinguishable with established SCr-defined criteria, suggesting that intravenous iodinated contrast media may not be the causative agent in diminished renal function after contrast material administration.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12121823/-/DC1.

Contrast material-induced nephrotoxicity and intravenous low-osmolality iodinated contrast material

PURPOSE

To determine whether intravenous low-osmolality iodinated contrast material is associated with post-computed tomography (CT) acute kidney injury (AKI).

MATERIALS AND METHODS

Institutional review board approval was obtained and patient consent waived for this HIPAA-compliant retrospective study. CT examinations performed over a 10-year period in adult inpatients with sufficient serum creatinine (SCr) data were identified. A one-to-one propensity-matched matched cohort analysis with multivariate analysis of effects was performed with post-CT AKI as the primary outcome measure (10,121 unenhanced and 10,121 intravenous contrast-enhanced CT examinations in 20,242 patients). Propensity matching was performed with respect to likelihood of patient receiving intravenous contrast material (36 tested covariates). The primary endpoint was post-CT AKI by using Acute Kidney Injury Network SCr criteria; the secondary endpoint was post-CT AKI by using traditional SCr criteria for contrast material-induced nephrotoxicity (CIN; SCr increase ≥0.5 mg/dL [44.20 μmol/L] or ≥25%). Multivariate subgroup threshold analysis was performed (SCr <1.5 [<132.60 μmol/L]; ≥1.5 to ≥2.0 mg/dL [≥132.60 to ≥176.80 μmol/L]) and adjusted for assigned propensity scores.

RESULTS

Intravenous low-osmolality iodinated contrast material had a significant effect on the development of post-CT AKI for patients with pre-CT SCr levels of 1.6 mg/dL (141.44 μmol/L) or greater (odds ratio, 1.45; 95% confidence interval [CI]: 1.11, 1.89;P = .007). This effect strengthened as pre-CT SCr increased. Patients with stable SCr less than 1.5 mg/dL (132.60 μmol/L) were not at risk for developing CIN (P = .25, power > 95%). Both endpoints demonstrated similar results (eg, SCr ≥1.6 mg/dL [141.44 μmol/L] by using traditional CIN criteria: odds ratio, 1.64; 95% CI: 1.18, 2.28; P = .003). Post-CT AKI was prevalent in both the unenhanced and contrast-enhanced CT subgroups, and it increased with increases in pre-CT SCr. Many risk factors contributed to development of post-CT AKI, regardless of iodinated contrast material.

CONCLUSION

Intravenous low-osmolality iodinated contrast material is a nephrotoxic risk factor, but not in patients with a stable SCr level less than 1.5 mg/dL. Many factors other than contrast material can affect post-CT AKI rates.

The Role of N--Acetylcysteine in the Prevention of Contrast-Induced Nephropathy in Patients Undergoing Peripheral Angiography

Contrast-induced nephropathy (CIN) is a leading cause of hospital-acquired acute kidney injury (AKI). N-acetylcysteine (NAC) was proposed as an effective preventative measure. As data in relation to the use of NAC for the prevention of CIN in peripheral angiography are lacking, a systematic review and meta-analysis were undertaken. A comprehensive search for the published and unpublished data was performed. Data were extracted from the eligible studies. Pooled odds ratios (ORs) were used to calculate the effect of NAC on CIN incidence. Pooled effect size estimates were used to calculate the effect of NAC on serum creatinine (SCr) postcontrast. Our results showed that NAC did not reduce CIN incidence (pooled OR 1.05; 95% confidence interval [CI] 0.38-2.88; P = .92) or the mean SCr levels (pooled weighted mean difference, 4.38; 95% CI 10.4-1.65; P = .15). In conclusion, insufficient evidence exists to recommend NAC for the prevention of CIN in patients undergoing peripheral angiography.

Contrast induced nephropathy in urology

Intravenous contrast agents have a distinct role in urological imaging: to study precise anatomical delineation, vascularity, and to assess the function of the renal unit. Contrast induced nephropathy (CIN) is a known adverse effect of intravenous contrast administration. The literature on incidence, pathophysiology, clinical features, and current preventive strategies available for CIN relevant to urologists was reviewed. A search of the PubMed database was done using the keywords nephropathy and media, prevention and control or prevention Contrast media (explode), all adverse effects, and kidney diseases (explode). An online search of the EMBASE database for the time ranging from 1977 to February 2009 was performed using the keywords ionic contrast medium, adverse drug reaction, major or controlled clinical study, human, nephrotoxicity, and kidney disease. Current publications and data most relevant to urologists were examined. CIN was the third most common cause of hospital-acquired renal failure. The incidence is less common with intravenous contrast administration as compared with intra-arterial administration. The pathogenesis of contrast mediated nephropathy is due to a combination of toxic injury to renal tubules and medullary ischemic injury mediated by reactive oxygen species. CIN most commonly manifests as a nonoliguric and asymptomatic transient decline in renal function. Patients who developed CIN were found to have increased mortality, longer hospital stay, and complicated clinical course. An overview of risk factors and risk prediction score for prognostication of CIN are elaborated. Preventive strategies including choice of contrast agents, maximum tolerated dose, role of hydration, hydration regime, etc. are discussed. The role of N- acetyl cysteine, Theophylline, Fenoldapam, Endothelin receptor antagonists, iloprost, atrial natriuretic peptide, and newer therapies such as targeted renal therapy (TRT) are discussed. A working algorithm based on current evidence is proposed. No current treatment can reverse or ameliorate CIN once it occurs, but prophylaxis is possible.

Does oral N-acetylcysteine reduce contrast-induced renal injury in patients with peripheral arterial disease undergoing peripheral angiography? A randomized-controlled study

The nephroprotective role of N-acetylcysteine (NAC) against contrast-induced nephropathy (CIN) in patients undergoing peripheral arterial angiography remains unclear. A total of 40 patients undergoing peripheral arterial angiography were randomized to receive intravenous (iv) hydration only (group 1) or oral NAC in addition to iv hydration (group 2; ISRCTN: 35882618). Primary outcome was reduction in the elevation of urinary retinol binding protein (RBP), albumin-creatinine ratio (ACR), and serum creatinine (serC). Groups 1 and 2 had equivocal percentage reduction in RBP and ACR levels from baseline (P = .80 and .30). A significant reduction in serC was, however, observed with NAC by third postprocedure day (P = .04). One patient in the treatment arm developed CIN compared with 3 patients in the control group (P = .33). Equivocal changes in RBP and ACR levels by both treatments seem to indicate that either is equally effective in affording renal protection.

In emergency situations, should serum creatinine be checked in all patients before performing second contrast CT examinations within 24 hours?

OBJECTIVE

The aim of this study was to determine the frequency of contrast-induced nephropathy (CIN) in patients undergoing repeat contrast-enhanced computed tomographic (CT) examinations within 24 hours, as well as associated risk factors.

MATERIALS AND METHODS

Through a search of medical and radiologic records, patients who underwent 2 contrast-enhanced CT examinations within 24 hours during a 4-year period (2003-2006), with available serum creatinine measurements before and after CT imaging were included. Medical records were reviewed for demographic data, risk factors, renal status, and CT contrast volume. The frequency of CIN was calculated, and odds ratios of risk factors were determined.

RESULTS

There were 164 patients (90 men, 74 women; mean age, 56.3 years), with an average baseline serum creatinine level of 1.02 +/- 0.73 mg/dL (range, 0.3-6.6 mg/dL). Three hundred twenty-eight CT examinations were performed: 2 in each patient, at an average interval of 11.4 hours. The mean doses of contrast medium used for the first and second CT examinations were 126.2 and 123.4 mL, respectively. Twenty-one patients (12.8%) developed CIN. Comparing patients with and without CIN, the only statistically significant risk factor for CIN was an increase in serum creatinine between the first and second CT examinations, with an odds ratio of 18 (P < .005).

CONCLUSION

The incidence of CIN in patients who underwent repeat contrast-enhanced CT examinations was 12.8%. An increase in serum creatinine between the first and second CT examinations was highly associated with CIN and may serve as a risk factor for developing CIN.

Cerebral CT angiography using a reduced dose of contrast material at high iodine concentration in combination with a saline flush

AIM

To determine whether cerebral computed tomography (CT) angiography with a 16-detector row system can be performed using a reduced dose of contrast material.

MATERIALS AND METHODS

Twenty-eight patients were assigned to one of four protocols: A=50 ml of 350 mg I/ml with a saline flush (SF, 40 ml); B=75 ml of 350 mg I/ml with an SF; C=75 ml of 350 mg I/ml without an SF; and D=100ml of 300 mg I/ml without an SF. The attenuation of the internal carotid, middle cerebral, and anterior cerebral arteries were measured. The demonstration of vessels was also assessed.

RESULTS

There were no significant attenuation differences of the arteries among the four groups, neither were any significant differences noted on the visual assessment.

CONCLUSIONS

By using a reduced dose (50 ml) at higher iodine concentration (350 mg I/ml) with an SF, CT angiograms comparable with those acquired with a standard dose and concentration can be obtained.

Waiting to exhale: salvaging the nondiagnostic CT pulmonary angiogram by using expiratory imaging to improve contrast dynamics

We attempted to investigate whether computed tomography pulmonary angiography (CTPA) in the expiratory phase can improve contrast enhancement of the pulmonary arteries and mitigate the effect of inspiratory transient attenuation artifact, potentially salvaging nondiagnostic studies. Eighteen patients with indeterminate inspiratory CTPA, despite proper contrast bolus were studied. Patients were rescanned in expiration using the same contrast bolus and scanning parameters. The attenuation of each pulmonary arterial segment, superior and inferior vena cava, and atria and ventricles during the two phases of respiration was measured independently by three radiologists. All pulmonary segments were evaluated for filling defects during the two phases. In addition, the studies were graded for diagnostic quality of enhancement and probable impact on management. A statistically significant increase in pulmonary arterial enhancement was seen during expiration from the pulmonary trunk to the segmental pulmonary arteries (P < 0.001) and for the inferior vena cava, the right atrium, and the ventricle. The incidence of nondiagnostic inspiratory studies ranged from 89 to 100%, depending on the observer. All studies were upgraded to fully acceptable diagnostic quality with follow-up expiratory imaging (P < 0.0001). Expiratory phase imaging was observed to have diagnostic impact in 78 to 88% of cases, with overall good to moderate interobserver agreement. In one case, pulmonary embolism was detected on the expiratory scan, which was not seen on the inspiratory scan. Expiratory imaging for nondiagnostic CTPA improves pulmonary arterial enhancement and improves diagnostic quality of CTPA by eliminating transient attenuation artifact, thus facilitating more accurate diagnosis and providing earlier treatment of pulmonary embolism.

Sixteen-Detector Row CT Angiography of the Brain

OBJECTIVE

The aim of this prospective study was to investigate the effect of different volumes of contrast material on vascular enhancement in 16-channel multi-detector row computed tomographic angiography of the brain.

METHODS

A total of 194 patients were divided into 3 groups who received different volumes of contrast material: 100 (n = 62), 80 (n = 72), and 60 mL (n = 60). The attenuation values were measured on transverse images at 12 different intracranial vessels (right and left internal carotid arteries, A2s, M2s, and P2s, basilar artery, vein of Galen, superior sagittal sinus, and dominant sigmoid sinus). The image quality parameters (intra-arterial contrast, arterial delineation, venous contamination, and confidence in diagnosis) were graded by 2 observers in consensus using a 5-point scale.

RESULTS

The attenuation values at the left A2 segment, superior sagittal sinus, and sigmoid sinus were significantly lower in the 60-mL group than those in other groups, whereas no significant differences were found between the 3 groups for the remaining intracranial vessels. For qualitative evaluation, arterial delineation was rated higher in the 100- and 80-mL groups, whereas less venous contamination was found in the 60-mL group. There was no significant difference in overall image quality (the sum of the scores for 4 image quality parameters) between the 3 groups.

CONCLUSIONS

A contrast material volume of 60 mL (18 g iodine) provides excellent image quality of cerebral multi-detector row computed tomographic angiography comparable to those achievable with 100 and 80 mL.

Severe methotrexate toxicity precipitated by intravenous radiographic contrast

Methotrexate (MTX), a widely used anticancer agent, and intravenous iodinated contrast used for radiographic studies can both cause acute renal failure. Their combined exposure may place patients at higher risk for renal failure. This report describes 2 pediatric patients with MTX toxicity precipitated by the use of intravenous radiographic contrast. One patient recovered with leucovorin rescue therapy, whereas the second patient responded to carboxypeptidase-G2. Both patients suffered MTX-related toxicities including myelosuppression and mucositis, but recovered full renal function and tolerated further high-dose MTX therapy. These cases suggest that intravenous iodinated contrast should be avoided in patients receiving high-dose MTX.

Value of single-dose contrast-enhanced magnetic resonance angiography versus intraarterial digital subtraction angiography in therapy indications in abdominal and iliac arteries

The objective of the study was to prove the value of single-dose contrast-enhanced magnetic resonance angiography [three-dimensional (3D) ceMRA] in abdominal and iliac arteries versus the reference standard intra-arterial digital subtraction angiography (i.a.DSA) when indicating a therapy. Patients suspected of having abdominal or iliac artery stenosis were included in this study. A positive vote of the local Ethics Committe was given. After written informed consent was obtained, 37 patients were enrolled, of which 34 were available for image evaluation. Both 3D ceMRA and i.a. DSA were performed for each patient. The dosage for 3D ceMRA was 0.1 mmol/kg body weight in a 1.5-T scanner with a phased-array coil. The parameters of the 3D-FLASH sequence were as follows: TR/TE 4.6/1.8 ms, effective thickness 3.5 mm, matrix 512 x 200, flip angle 30 degrees , field of view 420 mm, TA 23 s, coronal scan orientation. Totally, 476 vessel segments were evaluated for stenosis degree by two radiologists in a consensus fashion in a blinded read. For each patient, a therapy was proposed, if clinically indicated. Sensitivity, specificity, positive and negative predictive values, and accuracy for stenoses > or = 50% were 68%, 92%, 44%, 97%, and 90%, respectively. In 13/34 patients, a discrepancy was found concerning therapy decisions based on MRA findings versus therapy decisions based on the reference standard DSA. The results showed that the used MRA imaging technique of abdominal and iliac arteries is not competitive to i.a. DSA, with a high rate of misinterpretation of the MRAs resulting in incorrect therapies.

Multi-detector row CT of the head and neck: comparison of different volumes of contrast material with and without a saline chaser

INTRODUCTION

The aim of this study was to determine the effect of different volumes of contrast material with and without a saline chaser on tissue enhancement in multidetector row CT (MDCT) of the head and neck.

METHODS

In a blind prospective fashion, 120 patients were randomized into the following four groups: group 1, 80 ml contrast material administered at a flow rate of 2.0 ml/s; group 2, 80 ml followed by 40 ml saline at 2.0 ml/s; group 3, 60 ml at 1.5 ml/s; and group 4, 60 ml followed by 30 ml saline at 1.5 ml/s. The attenuation values of the carotid artery, internal jugular vein, and muscle were measured at an interval of 1.5 s in each patient. The degree of perivenous artifacts was subjectively assessed.

RESULTS

Mean attenuation values in the carotid artery and internal jugular vein were significantly higher in groups 1 and 2 than in groups 3 and 4. The width of the diagnostic window (both carotid and jugular enhancement >150 HU) were significantly longer in groups 1 and 2 than in groups 3 and 4. The addition of a saline chaser did not result in improved vascular enhancement or a wider diagnostic window, but reduced perivenous artifacts, compared with using contrast material alone.

CONCLUSION

Reduction of contrast material from 80 to 60 ml results in insufficient enhancement of neck vessels. In addition, the benefit of a saline chaser technique is not obvious except for its ability to reduce perivenous artifacts.

Risk of Nephropathy after Intravenous Administration of Contrast Material: A Critical Literature Analysis

PURPOSE

To assess the risk of nephropathy after administration of contrast material by reviewing the published literature on intravenous contrast material administration and by separating reports with appropriate control measures from those without such measures.

MATERIALS AND METHODS

The MEDLINE database was searched for articles published from October 1966 to September 2004 that contained the phrases "contrast," "contrast medium," "contrast media," or "radiocontrast" and any of the words or phrases "nephrotoxicity," "nephropathy," kidney failure," or "renal failure." The identified publications were reviewed and limited to original clinical series. Studies were categorized according to the route of contrast material administration. Those in which an identifiable group of patients received contrast material intravenously were further evaluated to determine which studies compared results with those from a control group of patients who did not receive contrast material.

RESULTS

Only 40 (1.3%) of 3081 publications had patients who received contrast material intravenously. Of these, only two publications had control groups of patients who received no contrast material. The incidence of postcontrast nephropathy in these two series was not substantially different from that in the control groups.

CONCLUSION

Properly controlled clinical studies of intravenously administered radiographic contrast media fail to demonstrate renal damage.

Safety and Effectiveness of Gadolinium-enhanced Multi–Detector Row Spiral CT Angiography of the Chest: Preliminary Results in 37 Patients with Contraindications to Iodinated Contrast Agents

PURPOSE

To prospectively evaluate the safety and effectiveness of gadolinium-enhanced multi-detector row spiral computed tomographic (CT) angiography of the pulmonary circulation by using two gadolinium doses in patients with contraindications to iodinated contrast agents.

MATERIALS AND METHODS

Study was approved by the Ethics Committee, and written informed consent was obtained. Thirty-seven patients (20 men, 17 women) with contraindications to iodinated contrast agents (allergic reactions, n = 27; impaired renal function, n = 10) underwent CT angiography of the pulmonary circulation in search of acute pulmonary embolism (n = 28) or for management of tumoral disease (n = 9). CT angiography was performed (a) with four-detector row (n = 19) or 16-detector row (n = 18) scanners; (b) at randomly assigned gadolinium doses of either 0.3 mmol per kilogram of body weight (n = 19) or 0.4 mmol/kg (n = 18); and (c) with a systematic evaluation of clinical and biologic tolerance of gadolinium. Comparison of percentages between group 1 and group 2 scans was performed with the chi2 or the Fisher exact test. An unpaired Wilcoxon rank sum test was used for numeric variables. P < .05 was considered to indicate a significant difference.

RESULTS

The mean (+/- standard deviation) volume of gadopentetate dimeglumine administered in the overall study group was 48 mL +/- 9.6 (range, 29-65 mL). The level of maximal enhancement in the pulmonary arteries was significantly higher in group 2 than in group 1 (215.8 HU +/- 95 vs 141.3 HU +/- 44) (P = .02) and was maintained throughout the entire region of interest in a greater number of examinations in group 2 than in group 1 (n = 16 [89%] vs n = 2 [10.5%]) (P < .0001). The number of diagnostic CT angiograms was significantly higher in group 2 than in group 1 (n = 17 [94%] vs n = 13 [68%]) (P = .007). Significant but transient reduction of creatinine clearance was observed in one patient with preexisting moderate chronic renal failure (0.3 mmol/kg gadolinium dose).

CONCLUSION

High-quality gadolinium-enhanced CT angiograms require the use of 16-detector row CT technology; the doses administered did not alter the renal function except transiently in one patient.

Fenoldopam andN-acetylcysteine for the Prevention of Radiographic Contrast Material-Induced Nephropathy: A Review

Radiographic contrast material-induced nephropathy (RCIN) is the third most common cause of hospital-acquired renal insufficiency and has been associated with an increase in patient mortality. Many strategies to prevent RCIN have been explored unsuccessfully. The standard of care remains hydration with 0.45% sodium chloride before and after administration of contrast material. Recently, N-acetylcysteine and fenoldopam have been studied to determine their efficacy in preventing RCIN. Of seven prospective studies using various dosing regimens of N-acetylcysteine, four revealed beneficial results. Although some discrepancies exist, the data strongly suggest that N-acetylcysteine has a role in patients at risk for the development of RCIN. The data for fenoldopam are more limited, with only one retrospective study showing benefit. Additional prospective data are required to determine if fenoldopam has a role in the prevention of RCIN.

Using a saline chaser to decrease contrast media in abdominal CT

OBJECTIVE

The purpose of this study was to compare hepatic tumor conspicuity on CT after injection of either 150 mL of contrast material or 100 mL of contrast material plus a 50-mL saline chaser.

SUBJECTS AND METHODS

We evaluated 86 hypoattenuating liver metastases in 26 patients. Patients underwent CT in two sessions separated by a mean of 85 days: one time with 150 mL of contrast material and the other time with 100 mL of contrast material followed by a 50-mL saline chaser. The order of the sessions was randomized. Contrast material was administered via power injector and matched for injection rate and delay time. Attenuation values were obtained from normal liver tissue and metastases and from the spleen, kidney, aorta, and inferior vena cava.

RESULTS

The 150 mL dose of contrast material caused slightly greater liver and tumor attenuation than 100 mL of contrast material with a chaser (mean hepatic attenuation, 95.6 vs 89.8 H, respectively; p < 0.03, paired t test; mean tumor attenuation, 53.2 vs 49.1 H, respectively; r = 0.71, p = 0.09). The difference in conspicuity of liver lesions was slightly greater with 150 mL than with 100 mL with a chaser (46.8 H vs 44.2 H; r = 0.46, p = 0.08, paired t test), but was of doubtful clinical significance (2.6 H). Kidney, spleen, and vascular structures enhanced more with 150 mL than with 100 mL and a chaser.

CONCLUSION

Using 100 mL of contrast material and a saline chaser did not result in a meaningful difference in liver parenchyma attenuation or lesion conspicuity compared with using 150 mL of contrast medium alone. Routine use of a chaser for abdominal CT may yield cost savings and a decreased risk of contrast nephropathy.

Contrast nephropathy : an evidence-based approach to prevention

Contrast-induced nephropathy occurs in 2-10% of patients exposed to intravascular radiographic contrast agents and results in significant morbidity and mortality. Although the exact mechanism of this disorder has not been fully elucidated, contrast nephropathy is probably due to a combination of decreased renal medullary blood flow, resulting in medullary ischemia, and direct toxicity to renal tubules. Contrast nephropathy is most commonly defined as either a >25% increase or a >0.5 mg/dL rise in serum creatinine level within 48 hours of contrast medium exposure. Baseline characteristics associated with an increased risk for development of contrast nephropathy include the presence of baseline renal dysfunction, diabetes mellitus, congestive heart failure, volume depletion, and concomitant administration of nephrotoxic drugs. Many strategies have been investigated in an effort to prevent the occurrence of renal dysfunction following contrast media exposure. Intravenous hydration has been shown to significantly decrease the incidence of nephropathy in high-risk patients. However, trials of several prophylactic pharmacologic interventions have been mostly disappointing, including the administration of calcium channel antagonists, diuretics, dopamine, endothelin receptor antagonists and fenoldopam. The use of N-acetylcysteine has been shown in some trials to decrease the incidence of contrast nephropathy in patients with a baseline renal dysfunction, and should currently be strongly considered in this high-risk patient subgroup in addition to hydration. Our purpose is to review the contemporary literature regarding contrast-induced renal dysfunction and present an evidence-based approach for prevention of this complication.

Renal cortical retention of contrast medium on delayed CT and nephropathy following transcatheter arterial chemoembolisation in patients with high serum creatinine level

The aim of this study was to investigate the prevalence of renal cortical retention (RCR) of contrast media seen on delayed CT, and nephropathy following transarterial chemoembolisation (TACE) in high-risk patients. The findings of 18 patients with abnormally high serum creatinine levels who underwent TACE were reviewed. Nephropathy was defined as an increase in serum creatinine level of more than 44 micromol l(-1), or more than 25%, on day 1, 3, 7 or 14. RCR was defined as mild (CT value >50) or severe (CT value >100). RCR was seen in 16 cases (89%) and in seven cases (39%) of post-TACE nephropathy. Patients without severe RCR did not develop nephropathy post-TACE, whereas 50% of those with such retention did (p=0.19). Delayed CT appears to have the potential as an early detector of nephropathy post-TACE in high-risk patients.