The PREDICT study: a randomized double-blind comparison of contrast-induced nephropathy after low- or isoosmolar contrast agent exposure. AJR Am J Roentgenol. 2008;191:151-157. [PMID: 18562739 DOI: 10.2214/ajr.07.3370]

Prevention of post-contrast kidney injury in patients with cancer

Post-contrast acute kidney injury is defined as a nephropathy with an increase in serum creatinine of >0.3 mg/dL (or >26.5 μmol/L) or >1.5-times the baseline within 48-72 h of intravascular administration of a contrast medium. Patients with cancer have an increased risk of post-contrast acute kidney injury not only related to the frequent use of contrast medium for computed tomography scans but also to other factors, including the type of tumour, age, oncological therapies, use of other nephrotoxic agents and dehydration. Preventive strategies were developed and may be applied to different risk profiles. Patients at risk may be detected by recently published risk scores.

Simultaneous antegrade urography of the upper urinary tract and retrograde cystography combined with computed tomography imaging in the management of ureteral complications after renal transplantation

Background

To investigate the significance of simultaneous urography of the upper and lower urinary tract of transplanted kidneys combined with computed tomography urography (CTU), computed tomography arteriography (CTA), and computed tomography venography imaging in the planning of open surgery performed to treat any ureteral complications of a transplanted kidney.

Methods

In all, 24 patients with ureteral complications after renal transplantation were admitted, 12 of whom had renal graft ostomy during open surgery. Simultaneous antegrade urography of the upper urinary tract and retrograde cystography of the transplanted kidneys were performed on the patients. With the use of computed tomography imaging results, surgical planning was carried out.

Results

All surgeries were successfully completed according to preoperative planning. Three patients underwent end-to-end anastomosis of the ureter and bladder muscle flap, 8 patients underwent ureterocystostomy, and 1 patient underwent an end-to-end ureteral anastomosis. After the follow-up up to now, all the patients had stable renal function, and no complications such as ureteral stenosis or urine leakage have thus far reoccurred in the transplanted kidneys.

Conclusions

When open surgery is required to treat any ureteral complications following renal transplantation, preoperative multiangle imaging can be used to better understand the condition of the transplanted urinary tract and thus aid considerably in surgical planning.

Facile Hydrothermal Synthesis of an Iodine-Doped Computed Tomography Contrast Agent Using Insoluble Triiodobenzene

Carbonized iodine-doped particles (CIPs) were developed to overcome the disadvantages of computed tomography (CT) contrast agents, such as high osmolality and the radiodensity dilution of monomolecular contrast agents and low solubility and high toxicity of polymeric contrast agents. The CIPs were synthesized via a hydrothermal synthesis for 8 h using ATIPA (5-amino-2,4,6-triiodoisophthalic acid), glycerol, and tromethamine in the presence of D.W. (deionized water)-insoluble ATIPA converted into CIPs through a hydrothermal synthesis, showing high solubility and low osmotic pressure. The in vitro contrast effect determined for the resulting CIPs demonstrated a 57.6% enhancement compared to iohexol, and the osmotic pressure of the resulting CIPs was lower than that of iohexol. In addition, the CIPs demonstrated no dilution-induced contrast decrease in plasma and, therefore, demonstrated high contrast strength in vivo. Cytotoxicity tests, hemolysis assays, and histological analyses were conducted to verify the biocompatibility of the CIP product; however, no toxicity was observed. Furthermore, the CIP demonstrated a much higher contrast effect than iohexol at low concentrations. These results indicate that the CIP we have produced may be used as an effective blood pool agent for CT imaging.

Comparative effect of iso-osmolar versus low-osmolar contrast media on the incidence of contrast-induced acute kidney injury in diabetic patients: a systematic review and meta-analysis

BACKGROUND

Contrast-induced acute kidney injury (CI-AKI) is a major adverse effect caused by intravascular administration of iodinated contrast medium. Whether there is a difference in CI-AKI incidence between iso-osmolar (IOCM) and low-osmolar contrast media (LOCM) among diabetic patients is controversial.

METHODS

Randomized controlled trials comparing the nephrotoxic effects between IOCM and LOCM in diabetic patients with or without CKD (eGFR< 60 ml/min/1.73 m2) were included in the analysis. The incidence of CI-AKI was defined as an initial increase in serum creatinine (SCr) concentration of at least 0.5 mg/dl or a rise in creatinine of 25% from baseline.

RESULTS

A total of 2190 patients were included, among whom 1122 patients received IOCM and 1068 received LOCM. When compared to LOCM, IOCM had no significant benefit in preventing CI-AKI (OR = 1.66, [CI: 0.97-2.84], P = 0.06, I2 = 54%). However, the difference between IOCM and LOCM was found when CI-AKI was defined as an absolute SCr increase (≥0.5 mg/dl) rather than a relative SCr increase (≥25%). Further analysis showed that LOCM resulted in more adverse events.

CONCLUSIONS

Whether there is a difference of CI-AKI incidence between IOCM and LOCM in diabetic patients was related to the selected diagnostic criteria. The incidence of adverse events was significantly lower with IOCM when compared with LOCM. Therefore, we suggest that IOCM may be used in diabetic and CKD (eGFR< 60 ml/min/1.73 m2) patients.

Contrast-induced nephropathy in patients with diabetes mellitus between iso- and low-osmolar contrast media: A meta-analysis of full-text prospective, randomized controlled trials

Purpose

This study was conducted to compare iso-osmolar contrast medium, iodixanol, with low-osmolar contrast media (LOCM) for assessing contrast-induced nephropathy (CIN) incidence, exclusively in the diabetic population.

Method

A systematic search was conducted for full-text, prospective, randomized controlled trials (RCTs). The primary outcome was incidence of CIN. Medline, Cochrane Central Register of Controlled Trials, and other sources were searched until May 31, 2017.

Results

Twelve RCTs finally met the search criteria. Iodixanol did not significantly reduce the risk of CIN (risk ratio [RR]: 0.72, 95% confidence interval (CI): [0.49, 1.04], p = 0.08). However, there was significantly reduced risk of CIN when iodixanol was compared to a LOCM agent iohexol (RR: 0.32, 95% CI [0.12, 0.89]). There were no differences between iodixanol and the other non-iohexol LOCM (RR: 0.92, 95% CI [0.68, 1.25]).

Conclusion

In diabetic populations, iodixanol is not associated with a significant reduction of CIN risk. Iodixanol is associated with a reduced risk of CIN compared with iohexol, whereas no significant difference between iodixanol and other LOCM could be found.

Acute Kidney Injury (AKI)

Kidneys perform a multitude of essential functions within the human body. Of these the most important are (1) maintaining pH through regulation of acid/base levels and (2) excreting end products of metabolism. As for most organ-systems, these functions are especially important for healing following trauma and/or surgery and decline with age. Acute Kidney Injury (AKI) is one of the common forms of organ failures seen in the ICU and elderly patients are more prone to it. The causes maybe classified as Prerenal (inadequate perfusion), renal (inherent kidney disease) and post-renal (urinary obstruction). Preventing AKI should be an important concern in all critically ill patients but especially important in the elderly patients since the development of AKI can significantly increase in-hospital mortality. Once AKI has set in a systematic and step-wise approach of diagnosis and management is key to avoiding adverse outcomes.

Acute Kidney Injury After Intravenous Versus Intra-Arterial Contrast Material Administration in a Paired Cohort

OBJECTIVES

The aim of this study was to determine whether intra-arterial administration of contrast material is associated with a higher risk of acute kidney injury (AKI) compared with that of intravenous (IV) administration in a cohort of patients that received both routes of administration.

MATERIALS AND METHODS

All patients who received both a contrast-enhanced computed tomography (CT) and a diagnostic or interventional cardiac catheterization between 2000 and 2014 were identified. Patients who lacked sufficient preprocedure and postprocedure serum creatinine results, who were on preexisting renal dialysis, or who underwent additional contrast-enhanced procedures within 7 days of either procedure were excluded. The rate of AKI (serum creatinine ≥0.3 mg/dL or 50% above baseline) was compared after CT scan and cardiac catheterization using McNemar test.

RESULTS

A total of 1969 patients met all study inclusion criteria. The rate of AKI after CT scan was similar to the rate after catheterization when examining all patients (9.9% CT vs 11% catheterization, P = 0.12). A similar rate of AKI after both procedures was observed regardless of procedure order, catheterization type, and patient baseline estimated glomerular filtration rate.

CONCLUSIONS

Intra-arterial administration of contrast material during cardiac catheterization had a similar risk of AKI as compared with that of CT scanning involving IV administration in a cohort of patients who underwent both procedures. These findings suggest that previously reported much higher rates of AKI after cardiac catheterization compared with that of IV contrast administration reflect higher baseline clinical risk factors for AKI in the former cohort compared with that in the latter.

Iodixanol versus iopromide in cancer patients: Evidence from a randomized clinical trial

To assess the safety profile of iso-osmolar contrast medium (CM) versus low osmolar CM in cancer patients with an estimated glomerular filtration rate (eGFR) >60 ml/min. In this multicenter, blind trial of patients seeking a chest-abdomen-pelvis contrast enhanced computed tomography (CT) with iodated CM, participants were centrally randomized to iodixanol or iopromide. Contrast induced nephropathy (CIN) at 24 and/or 72 hr were our primary outcomes. We further considered irreversible CIN, average eGFR percentage variation (%Δ), and adverse events (AEs). Overall, 607 patients were enrolled. Among them, 497 eligible patients were randomized to iodixanol (N: 247) or iopromide (N: 250). No differences emerged by descriptive characteristics. Seven and 3 CIN at 24 hr (p = 0.34) and 8 and 2 CIN at 72 hr (p = 0.11) occurred in the iopromide and iodixanol group, respectively. Within the subgroup of individual patients who developed CIN (N: 17), the event rate was higher in the iopromide arm (p = 0.045). No cases of permanent CIN or significant differences in terms of AEs or GFR %Δ were observed. Our results suggest a more favorable safety profile of iodixanol versus iopromide. Adequately sized trials with similar design are warranted to confirm our findings and clarify the underlying biological mechanisms.

Contrast-induced acute kidney injury: A review of practical points

Contrast-induced acute kidney injury (CI-AKI) is one of the most common causes of AKI in clinical practice. CI-AKI has been found to be strongly associated with morbidity and mortality of the patients. Furthermore, CI-AKI may not be always reversible and it may be associated with the development of chronic kidney disease. Pathophysiology of CI-AKI is not exactly understood and there is no consensus on the preventive strategies. CI-AKI is an active research area thus clinicians should be updated periodically about this topic. In this review, we aimed to discuss the indications of contrast-enhanced imaging, types of contrast media and their impact on nephrotoxicity, major pathophysiological mechanisms, risk factors and preventive strategies of CI-AKI and alternative non-contrast-enhanced imaging methods.

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.

StatSensor-i point-of-care creatinine analyzer may identify patients at high-risk of contrast-induced nephropathy

The current study assessed the accuracy of the StatSensor-i (STA) point-of-care creatinine analyzer prior to and following adjustment (offset correction) by linear regression scatter plots produced by the reference samples from patients and volunteers for detecting high risk of contrast-induced nephropathy in patients with an estimated glomerular filtration rate <45 ml/min/1.73 m². Blood samples were obtained from 233 consecutive outpatients scheduled for contrast-enhanced CT studies. Of the 233 patients, 123 patient samples were evaluated prior to adjustment and the other 110 following adjustment. Serum creatinine levels and estimated glomerular filtration rate were measured using the analyzer and compared with the values returned by laboratory tests. Analysis was with the paired t-test, the Pearson correlation coefficient and Bland-Altman plotting. The sensitivity, specificity, positive and negative predictive values (PPV, NPV), and accuracy for detecting patients with an estimated glomerular filtration rate <45 ml/min/1.73 m² were subsequently calculated. Mean serum creatinine levels measured with the analyzer were significantly higher than those returned by laboratory tests before (P<0.0001) and after adjustment (P<0.01). Following adjustment, the difference in serum creatinine values obtained with the STA analyzer and by laboratory methods did not exceed 0.3 mg/dl. Prior to adjustment, 9.7% of the samples were overdiagnosed as having an estimated glomerular filtration rate of <45 ml/min/1.73 m²; following adjustment, the overdiagnosis rate was 2.7%. The sensitivity, specificity, PPV, NPV and accuracy were 100, 89, 50, 100 and 90.2% before and 100, 96.3, 33.3, 100 and 96.4% after adjustment, respectively. With the adjusted point-of-care creatinine analyzer, estimated glomerular filtration rate may be reliably evaluated in the radiology suite.

Contrast media use in patients with chronic kidney disease undergoing coronary angiography: A systematic review and meta-analysis of randomized trials

BACKGROUND

Patients with chronic kidney disease (CKD) undergoing coronary angiography (CA), adequate hydration and minimizing volume of contrast media (CM) are class 1b recommendations for preventing contrast induced nephropathy (CIN). Current data are insufficient to justify specific recommendations about isoosmolar vs. low-osmolar contrast media by the ACCF/AHA/SCAI guidelines.

METHODS

Randomized trials comparing IOCM to LOCM in CKD stage 3 and above patients undergoing CA, and reporting incidence of CIN (defined by a rise in creatinine of 25% from baseline) were included in the analysis. The secondary outcome of the study was the incidence of serum creatinine increase by >1mg/dl.

RESULTS

A total of 2839 patients were included in 10 trials, in which 1430 patients received IOCM and 1393 received LOCM. When compared to LOCM, IOCM was not associated with significant benefit in preventing CIN (OR=0.72, [CI: 0.50-1.04], P=0.08, I2=59%). Subgroup analysis revealed non-significant difference in incidence of CIN based on baseline use of N-acetylcystine (NAC), diabetes status, ejection fraction, and whether percutaneous coronary intervention vs coronary angiography alone was performed. The difference between IOCM and LOCM was further attenuated when restricted to studies with larger sample size (>250 patients) (OR=0.93; [CI: 0.66-1.30]) or when compared with non-ionic LOCM (OR=0.79, [CI: 0.52-1.21]).

CONCLUSION

In patients with CKD stage 3 and above undergoing coronary angiography, use of IOCM showed overall non-significant difference in incidence of CIN compared to LOCM. The difference was further attenuated when IOCM was compared with non-ionic LOCM.

Renal Safety of Iodinated Contrast Media Depending on Their Osmolarity - Current Outlooks

Iodinated contrast media (ICM) are commonly administered pharmaceutical agents. Most often they are used intravenously and intraarterially. Although iodinated contrast agents are relatively safe and widely used, adverse events occur and questions remain about their use, safety, and interactions. The most important adverse effects of contrast media include hypersensitivity reactions, thyroid dysfunction, and contrast-induced nephropathy. Radiologists must be aware of the risk factors for reactions to contrast media. Nonionic iodinated contrast agents can be divided into monomeric, low-osmolar, and dimeric, iso-osmolar classes. The osmotic characteristics of contrast media have been a significant focus in many investigations of contrast-induced nephropathy.

Adverse effects of drugs on the kidney

The number of drugs presently marketed is countless, their prescription is relentlessly growing, such that the likelihood of adverse effects is strikingly increasing. As many drugs are cleared by the body through kidney excretion, renal adverse events are likely. In this review we shall concisely describe the pathophysiologic mechanisms of renal damage by drugs, the different clinical presentations outlining renal toxicity in the course of pharmacologic treatment, and the main offending agents.

Contrast-induced nephropathy in CT: incidence, risk factors and strategies for prevention

In the past, a high percentage of hospital-acquired renal failure was attributed to contrast media. That position is now very controversial. Recently, doubts have been raised regarding the real relationship between acute kidney injury and intravenous contrast media administration. Similarly, statements about specific methods of preventing contrast-inducing nephropathy have been challenged. This review article addresses the controversies of incidence, causation, and prevention in an attempt to help the practicing radiologist adopt methods for their own department.

KEY POINTS

• The reported CIN incidence ranges from 2-12 % following contrast-enhanced CT. • Studies without a non-contrast CT control group may overestimate CIN incidence. • Development and application of a comprehensive CIN prevention strategy is recommended.

Automated contrast medium monitoring system for computed tomography--Intra-institutional audit

The aim of this study was to analyze the usage and the data recorded by a RIS-PACS-connected contrast medium (CM) monitoring system (Certegra(®), Bayer Healthcare, Leverkusen, Germany) over 19 months of CT activity. The system used was connected to two dual syringe power injectors (each associated with a 16-row and a high definition 64-row multidetector CT scanner, respectively), allowing to manage contrast medium injection parameters and to send and retrieve CT study-related information via RIS/PACS for any scheduled contrast-enhanced CT examination. The system can handle up to 64 variables and can be accessed via touchscreen by CT operators as well as via a web interface by registered users with three different hierarchy levels. Data related to CM injection parameters (i.e. iodine concentration, volume and flow rate of CM, iodine delivery rate and iodine dose, CM injection pressure, and volume and flow rate of saline), patient weight and height, and type of CT study over a testing period spanning from 1 June 2013 to 10 January 2015 were retrieved from the system. Technical alerts occurred for each injection event (such as system disarm due to technical failure, disarm due to operator's stop, incomplete filling of patient data fields, or excessively high injection pressure), as well as interoperability issues related to data sending and receiving to/from the RIS/PACS were also recorded. During the testing period, the CM monitoring system generated a total of 8609 reports, of which 7629 relative to successful injection events (88.6%). 331 alerts were generated, of which 40 resulted in injection interruption and 291 in CM flow rate limitation due to excessively high injection pressure (>325 psi). Average CM volume and flow rate were 93.73 ± 17.58 mL and 3.53 ± 0.89 mL/s, and contrast injection pressure ranged between 5 and 167 psi. A statistically significant correlation was found between iodine concentration and peak IDR (rs=0.2744, p<0.0001), as well as between iodine concentration and iodine dose (rs=0.3862, p<0.0001) for all CT studies. Automated contrast management systems can provide a full report of contrast use with the possibility to systematically compare different contrast injection protocols, minimize errors, and optimize organ-specific contrast enhancement for any given patient and clinical application. This can be useful to improve and harmonize the quality and consistency of contrast CT procedures within the same radiological department and across the hospital, as well as to monitor potential adverse events and overall costs.

Changing practice to prevent contrast-induced nephropathy

Based on updated evidence, a radiology nurse systematically engaged a multidisciplinary staff in testing a protocol to prevent contrast-induced nephropathy related to computed tomography. In a quality improvement project, the protocol combined preprocedure oral hydration with postprocedure intravenous saline. This protocol safely improved kidney function, reduced postprocedure time, and decreased annual cost. By applying theory, being persistent, presenting sound evidence, and unifying the team, one concerned staff nurse profoundly affected patient care and policy in an entire medical center.

The Choice of the Iodinated Radiographic Contrast Media to Prevent Contrast-Induced Nephropathy

In patients with preexisting renal impairment, particularly those who are diabetic, the iodinated radiographic contrast media may cause contrast-induced nephropathy (CIN) or contrast-induced acute kidney injury (CI-AKI), that is, an acute renal failure (ARF), usually nonoliguric and asymptomatic, occurring 24 to 72 hours after their intravascular injection in the absence of an alternative aetiology. Radiographic contrast media have different osmolalities and viscosities. They have also a different nephrotoxicity. In order to prevent CIN, the least nephrotoxic contrast media should be chosen, at the lowest dosage possible. Other prevention measures should include discontinuation of potentially nephrotoxic drugs, adequate hydration with i.v. infusion of either normal saline or bicarbonate solution, and eventually use of antioxidants, such as N-acetylcysteine, and statins.

Randomised trial of no hydration vs. sodium bicarbonate hydration in patients with chronic kidney disease undergoing acute computed tomography-pulmonary angiography

BACKGROUND

Hydration to prevent contrast-induced acute kidney injury (CI-AKI) induces a diagnostic delay when performing computed tomography-pulmonary angiography (CTPA) in patients suspected of having acute pulmonary embolism.

AIM

To analyze whether withholding hydration is non-inferior to sodium bicarbonate hydration before CTPA in patients with chronic kidney disease (CKD).

METHODS

We performed an open-label multicenter randomized trial between 2009 and 2013. One hundred thirty-nine CKD patients were randomized, of whom 138 were included in the intention-to-treat population: 67 were randomized to withholding hydration and 71 were randomized to 1-h 250 mL 1.4% sodium bicarbonate hydration before CTPA. Primary outcome was the increase in serum creatinine 48-96 h after CTPA. Secondary outcomes were the incidence of CI-AKI (creatinine increase > 25%/> 0.5 mg dL(-1) ), recovery of renal function, and the need for dialysis within 2 months after CTPA. Withholding hydration was considered non-inferior if the mean relative creatinine increase was ≤ 15% compared with sodium bicarbonate.

RESULTS

Mean relative creatinine increase was -0.14% (interquartile range -15.1% to 12.0%) for withholding hydration and -0.32% (interquartile range -9.7% to 10.1%) for sodium bicarbonate (mean difference 0.19%, 95% confidence interval -5.88% to 6.25%, P-value non-inferiority < 0.001). CI-AKI occurred in 11 patients (8.1%): 6 (9.2%) were randomized to withholding hydration and 5 (7.1%) to sodium bicarbonate (relative risk 1.29, 95% confidence interval 0.41-4.03). Renal function recovered in 80.0% of CI-AKI patients within each group (relative risk 1.00, 95% confidence interval 0.54-1.86). None of the CI-AKI patients developed a need for dialysis.

CONCLUSION

Our results suggest that preventive hydration could be safely withheld in CKD patients undergoing CTPA for suspected acute pulmonary embolism. This will facilitate management of these patients and prevents delay in diagnosis as well as unnecessary start of anticoagulant treatment while receiving volume expansion.

Acute kidney injury by radiographic contrast media: pathogenesis and prevention

It is well known that iodinated radiographic contrast media may cause kidney dysfunction, particularly in patients with preexisting renal impairment associated with diabetes. This dysfunction, when severe, will cause acute renal failure (ARF). We may define contrast-induced Acute Kidney Injury (AKI) as ARF occurring within 24-72 hrs after the intravascular injection of iodinated radiographic contrast media that cannot be attributed to other causes. The mechanisms underlying contrast media nephrotoxicity have not been fully elucidated and may be due to several factors, including renal ischaemia, particularly in the renal medulla, the formation of reactive oxygen species (ROS), reduction of nitric oxide (NO) production, and tubular epithelial and vascular endothelial injury. However, contrast-induced AKI can be prevented, but in order to do so, we need to know the risk factors. We have reviewed the risk factors for contrast-induced AKI and measures for its prevention, providing a long list of references enabling readers to deeply evaluate them both.

Relative Nephrotoxicity of Different Contrast Media

Contrast-induced nephropathy (CIN) is a common cause of acute kidney injury among hospitalized patients. High-osmolar contrast agents are associated with increased risk of CIN. Low-osmolar (LOCM) and iso-osmolar (IOCM) agents show no difference in the incidence of CIN, even among high-risk patients. This finding suggests that factors other than osmolality may play a role in the pathogenesis of CIN. The use of either LOCM or IOCM agents is recommended in high-risk patients.

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.

Is contrast medium osmolality a causal factor for contrast-induced nephropathy?

The exact pathophysiology of contrast-induced nephropathy (CIN) is not fully clarified, yet the osmotic characteristics of contrast media (CM) have been a significant focus in many investigations of CIN. Osmotic effects of CM specific to the kidney include transient decreases in blood flow, filtration fraction, and glomerular filtration rate. Potentially significant secondary effects include an osmotically induced diuresis with a concomitant dehydrating effect. Clinical experiences that have compared the occurrence of CIN between the various classes of CM based on osmolality have suggested a much less than anticipated advantage, if any, with a lower osmolality. Recent animal experiments actually suggest that induction of a mild osmotic diuresis in association with iso-osmolar agents tends to offset potentially deleterious renal effects of high viscosity-mediated intratubular CM stagnation.

Canadian Association of Radiologists consensus guidelines for the prevention of contrast-induced nephropathy: update 2012

PURPOSE

Contrast-induced acute kidney injury or contrast-induced nephropathy (CIN) is a significant complication of intravascular contrast medium (CM). These guidelines are intended as a practical approach to risk stratification and prevention. The major risk factor that predicts CIN is pre-existing chronic kidney disease.

METHODS

Members of the committee represent radiologists and nephrologists across Canada. The previous guidelines were reviewed, and an in-depth up-to-date literature review was carried out.

RESULTS

A serum creatinine level (SCr) should be obtained, and an estimated glomerular filtration rate (eGFR) should be calculated within 6 months in the outpatient who is stable and within 1 week for inpatients and patients who are not stable. Patients with an eGFR of ≥ 60 mL/min have an extremely low risk of CIN. The risk of CIN after intra-arterial CM administration appears be at least twice that after intravenous administration. Fluid volume loading remains the single most important measure, and hydration regimens that use sodium bicarbonate or normal saline solution should be considered for all patients with GFR < 60 mL/min who receive intra-arterial contrast and when GFR < 45 mL/min in patients who receive intravenous contrast. Patients are most at risk for CIN when eGFR < 30 mL/min. Additional preventative measures include the following: avoid dehydration, avoid CM when appropriate, minimize CM volume and frequency, avoid high osmolar CM, and discontinue nephrotoxic medications 48 hours before administration of CM.

The incidence of contrast-induced nephropathy (CIN) following transarterial chemoembolisation (TACE) in patients with hepatocellular carcinoma (HCC)

PURPOSE

The purpose of this retrospective study was to investigate the incidence of contrast-induced nephropathy (CIN) caused by transarterial chemoembolisation (TACE) in patients with hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

One hundred forty-one patients treated between 2005 and 2008 undergoing 305 consecutive sessions of TACE were enrolled. CIN was defined as an increase in the serum creatinine level of more than 0.5 mg/dl or more than 25 % from baseline within 3 days after TACE without any other identifiable cause of acute kidney injury.

RESULTS

CIN by the present definition was observed after 2.6 % of the TACE sessions. No patient showed clinical signs or symptoms of acute renal failure, or required haemodialysis. None of the patients with an estimated glomerular filtration rate of <60 ml/min/1.73 m(2) developed CIN.

CONCLUSION

The present study suggests that TACE is a relatively safe procedure in terms of the risk of CIN under vigorous periprocedural hydration and that the incidence of CIN is comparable to that of AKI associated with intravenous CM administration.

KEY POINTS

• CIN would be lower for non-coronary arterial intervention than for coronary intervention. • The present study suggests that the CIN rates following TACE are low. • The incidence of CIN is comparable to that after intravenous CM administration.

Risk of intravenous contrast material-mediated acute kidney injury: a propensity score-matched study stratified by baseline-estimated glomerular filtration rate

PURPOSE

To determine the effect of baseline estimated glomerular filtration rate (eGFR) on the causal association between intravenous iodinated contrast material exposure and subsequent development of acute kidney injury (AKI) in propensity score-matched groups of patients who underwent contrast material-enhanced or unenhanced computed tomography (CT).

MATERIALS AND METHODS

This retrospective study was HIPAA compliant and institutional review board approved. All patients who underwent contrast-enhanced (contrast material group) or unenhanced (non-contrast material group) CT between 2000 and 2010 were identified and stratified according to baseline eGFR by using Kidney Disease Outcomes Quality Initiative cutoffs for chronic kidney disease into subgroups with eGFR of 90 or greater, 60-89, 30-59, and less than 30 mL/min/1.73 m(2). Propensity score generation and 1:1 matching of patients were performed in each eGFR subgroup. Incidence of AKI (serum creatinine [SCr] increase of ≥0.5 mg/dL [≥44.2 μmol/L] above baseline) was compared in the matched subgroups by using the Fisher exact test.

RESULTS

A total of 12 508 propensity score-matched patients with contrast-enhanced and unenhanced scans met all inclusion criteria. In this predominantly inpatient cohort, the incidence of AKI significantly increased with decreasing baseline eGFR (P < .0001). However, this incidence was not significantly different between contrast material and non-contrast material groups in any eGFR subgroup; for the subgroup with eGFR of 90 or greater (n = 1642), odds ratio (OR) was 0.91 (95% confidence interval [CI]: 0.38, 2.15), P = .82; for the subgroup with eGFR of 60-89 (n = 3870), OR was 1.03 (95% CI: 0.66, 1.60), P = .99; for the subgroup with eGFR of 30-59 (n = 5510), OR was 0.94 (95% CI: 0.76, 1.18), P = .65; and for the subgroup with eGFR of less than 30 mL/min/1.73 m(2) (n = 1486), OR was 0.97 (95% CI: 0.72, 1.30), P = .89.

CONCLUSION

Diminished eGFR is associated with an increased risk of SCr-defined AKI following CT examinations. However, the risk of AKI is independent of contrast material exposure, even in patients with eGFR of less than 30 mL/min/1.73 m(2).

Plasma neutrophil gelatinase-associated lipocalin (NGAL) as an early predictive marker of contrast-induced nephropathy in hospitalized patients undergoing computed tomography

Background

Contrast-induced nephropathy (CIN) is a common cause of hospital-acquired acute kidney injury (AKI). Neutrophil gelatinase-associated lipocalin (NGAL) represents a promising biomarker for AKI. Its role in the early diagnosis of CIN has already been examined in adults and children undergoing coronary angiography. This study was designed to prospectively evaluate plasma NGAL compared with serum creatinine (SCr) for early CIN detection among hospitalized patients undergoing contrast-enhanced computed tomography (CT).

Methods

We prospectively enrolled consecutive hospitalized patients undergoing elective CT with intravenous (IV), low-osmolar contrast administration. Patients with pre-procedure SCr >150 μmol/L (1.7 mg/dL), congestive heart failure, haemodynamic instability, sepsis, or urinary tract infection were excluded. Plasma NGAL was measured using the standardized Triage^® NGAL test (Biosite Incorporated, San Diego, CA, USA) at baseline and 6 h post-procedure. SCr, blood urea nitrogen (BUN), albumin and sodium (Na) were measured and eGFR MDRD₄ was calculated at the same intervals, as well as at 24 and 48 h post-procedure. CIN was defined as an increase in SCr of >25% or >44 μmol/L (0.5 mg/dL) from baseline within 48 h post-procedure, in the absence of other obvious causes.

Results

Forty-seven patients, male/female 27/20, median age 68 (31–88) years, 16/47 diabetics, with baseline SCr 91.94 ± 20.33 μmol/L (1.04 ± 0.23 mg/dL) and eGFR MDRD₄ 68.40 ± 18.22 mL/min/1.73 m² were enrolled. A contrast volume of 120 mL (range 100–150 mL) was administered. CIN was found in four subjects (8.51%), but detection by SCr was only possible 24 h in 1 and 48 h post-procedure in three. In contrast, significant elevation of plasma NGAL was found at 6 h post-procedure in those with versus those without CIN (779.25 ± 361.49 versus 82.30 ± 40.64 ng/mL, P < 0.001). Using a cutoff value of 200 ng/mL, sensitivity, specificity and area under the receiver-operating characteristic (ROC) curve of 6-h plasma NGAL for CIN prediction were excellent (100, 100 and 1.00%, respectively). Subjects with CIN did not differ in baseline demographics, renal function and diabetes status compared with those without CIN. No differences in any variable were noted between diabetics and non-diabetics. Plasma NGAL at 6 h (R² = 0.24, P < 0.001) was found to be an independent predictor of CIN.

Conclusions

Plasma NGAL 6 h after contrast administration measured by the rapid, point-of-care Triage^® NGAL test appears to be a useful biomarker in the early prediction of CIN among hospitalized patients undergoing elective contrast-enhanced CT. However, the small sample size and the very small number of CIN events are important limitations. In any case, according to our evaluation, CIN incidence in this well-controlled population underlines the importance of early detection by an adequate and simple procedure such as the 6-h plasma NGAL test.

Contrast induced nephropathy in patients undergoing intravenous (IV) contrast enhanced computed tomography (CECT) and the relationship with risk factors: a meta-analysis

PURPOSE

To summarize the incidence of contrast-induced nephropathy (CIN) and associations between CIN incidence and risk factors in patients undergoing intravenous contrast-enhanced computed tomography (CECT) with low- or iso-osmolar iodinated contrast medium.

METHODS

This review is performed in accordance with the preferred reporting items in systematic reviews and meta-analysis (PRISMA) guidelines. We searched the MEDLINE, EMBASE and Cochrane databases from 2002 till November 2012. Two reviewers included papers and extracted data. The pooled data were analysed by either fixed or random-effects approach depending on heterogeneity defined as the I(2) index.

RESULTS

42 articles with 18,790 patients (mean age 61.5 years (range: 38-83 years)) were included. The mean baseline eGFR was 59.8 mL/min and ranged from 4 to 256 mL/min. Of all patients 45.0% had an estimated glomerular filtration rate (eGFR)<60 mL/min, 55.2% had hypertension; 20.2% had diabetes mellitus (DM) and 6.5% had congestive heart failure (CHF). The overall pooled CIN incidence, defined as a SCr increase of ≥ 25% or ≥ 0.5mg/dL, was 4.96% (95%CI: 3.79-6.47). Data analysis showed associations between CIN and the presence of renal insufficiency, DM, malignancy, age>65 years and use of non-steroidal anti-inflammatory drugs (NSAID's) with odds ratios of 1.73 (95%CI: 1.06-2.82), 1.87 (95%CI: 1.55-2.26), 1.79 (95%CI: 1.03-3.11), 1.95 (95%CI: 1.02-3.70) and 2.32 (95%CI: 1.04-5.19), respectively while hypertension, anaemia and CFH were not associated (p=0.13, p=0.38, p=0.40).

CONCLUSION

The mean incidence of CIN after intravenous iodinated CECT was low and associated with renal insufficiency, diabetes, presence of malignancy, old age and NSAID's use.

Glomerular filtration rate in evaluation of the effect of iodinated contrast media on renal function

OBJECTIVE

The purpose of this study was to use measured glomerular filtration rate (GFR), the reference standard of renal function, to assess the deleterious effect of iodinated contrast media on renal function. Such an effect has been traditionally defined as a greater than 0.5-mg/dL increase in serum creatinine concentration or a 25% or greater increase 24-72 hours after the injection of iodinated contrast medium.

SUBJECTS AND METHODS

This pilot investigation was focused on the consequences of clinically indicated IV injection of iodinated contrast media; intraarterial injection was excluded. One hundred thirteen patients with normal serum creatinine concentrations were enrolled in an approved protocol. At random, as chosen by one of the investigators, patients underwent imaging with one of three monomeric agents (iopamidol 300, iopromide 300, iohexol 300) and one dimeric agent (iodixanol 320). Measured GFR was determined immediately before CT and approximately 3 and 72 hours after the contrast injection for the CT examination. Iodinated contrast medium, a glomerular filtrate with no tubular excretion or reabsorption, was the GFR marker. Measured GFR was determined by x-ray fluorescence analysis with nonisotopic iodinated contrast media.

RESULTS

Monomeric and dimeric contrast agents in diagnostic CT volumes (based on bodyweight and imaging protocol) did not induce a significant change in measured GFR (95% confidence by Wilcoxon test), suggesting that use of the evaluated contrast media will not lead to more than a 12% variation.

CONCLUSION

The three monomeric agents studied and the one dimeric agent were equivalent in terms of lack of a significant effect on measured GFR when administered to patients with a normal GFR.

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.

The role of head computed tomography imaging in the evaluation of postoperative neurologic deficits in cardiac surgery patients

BACKGROUND

Computed tomography (CT) scans of the head without contrast are routinely obtained to evaluate neurologic deficits after cardiac surgery, but their utility is unknown. We evaluated our experience with this imaging modality to determine its value.

METHODS

We retrospectively identified cardiac surgery patients with postoperative neurologic deficits occurring during the first week after surgery between January 2000 and December 2012. Stroke was defined by neurologist's determination, whereas a nonfocal deficit (NFD) was defined by the presence of seizure, delirium, or cognitive impairment. We defined early noncontrast head CT as occurring within 7 days of surgery. Outcomes included positive findings on CT, in-hospital mortality, and length of stay. Multivariate logistic regression identified predictors of positive findings on head CT.

RESULTS

Within the population of 11,070 postoperative patients, 451 had early noncontrast head CT scans (4%). Two hundred two (44.7%) were associated with stroke, and 249 (55.2%) were associated with NFD. Among stroke patients, 40 of 202 (20%) showed acute infarction, 17 of 202 (8%) showed subacute infarction, and 5 of 202 (2%) showed hemorrhage. Among NFD patients, 1 of 248 (0.4%) showed acute infarction, 4 of 248 (1.6%) showed subacute infarction, and 1 of 248 (0.4%) showed hemorrhage. There was no difference in in-hospital mortality (stroke, 42 of 201 [21%] versus NFD, 41 of 248 [16%]; p = 0.2) or length of stay (stroke, 24 d versus NFD, 22 d; p = 0.5). On multivariable logistic regression, only focal deficits and aortic procedures predicted a positive finding on CT scan.

CONCLUSIONS

This study reviewed the utility of early postoperative noncontrast head CT in cardiac surgery patients. With focal neurologic deficits, this imaging modality was positive for approximately one third of patients, but rarely positive for NFD. Its use in this setting has limited utility.