Contrast media and nephropathy: findings from systematic analysis and Food and Drug Administration reports of adverse effects

Effects of Low-Osmolar Contrast Media on Long-Term Renal Impairment After Coronary Angiography: Iohexol Versus Iopromide

To investigate the long-term effects of 2 commonly used low-osmolar contrast media, iohexol and iopromide, on renal function and survival in patients who underwent coronary angiography. A total of 14,141 cardiology patients from 2006 to 2013 were recruited, of whom 1,793 patients (679 patients on iohexol and 1,114 on iopromide) were evaluated for long-term renal impairment and 5,410 patients (1,679 patients on iohexol and 3,731 on iopromide) were admitted for survival analyses spanning as long as 15 years. Univariate and multivariate logistic regression were used to explore the risk factors for long-term renal impairment. Cox proportional hazard regression was used to investigate the risk factors affecting survival. Propensity score matching and inverse probability of treatment weighting were applied to balance the baseline clinical characteristics. Patients receiving iohexol demonstrated a greater occurrence of renal impairment compared with those who received iopromide. Such difference remained consistent both before and after propensity score matching or inverse probability of treatment weighting, with a statistical significance of p <0.05. Among clinical variables, receiving contrast-enhanced contrast tomography/magnetic resonance imaging during follow-up, antihypertensive medication usage, presence of proteinuria, and anemia were identified as risk factors for long-term renal impairment (p = 0.041, 0.049, 0.006, and 0.029, respectively). During survival analyses, the difference was insignificant after propensity score matching and inverse probability of treatment weighting. In conclusion, administration of iohexol was more likely to induce long-term renal impairment than iopromide, particularly among patients diagnosed with anemia and proteinuria and those taking antihypertensive medication and with additional contrast exposure. The all-cause mortality, however, showed no significant difference between iohexol and iopromide administration.

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

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

Cloud-based fusion imaging improves operative metrics during fenestrated endovascular aneurysm repair

OBJECTIVE

Endovascular treatment of complex aortic pathology has been associated with increases in procedural-related metrics, including the operative time and radiation exposure. Three-dimensional fusion imaging technology has decreased the radiation dose and iodinated contrast use during endovascular aneurysm repair. The aim of the present study was to report our institutional experience with the use of a cloud-based fusion imaging platform during fenestrated endovascular aneurysm repair (FEVAR).

METHODS

A retrospective review of a prospectively maintained aortic database was performed to identify all patients who had undergone FEVAR with commercially available devices (Zenith Fenestrated; Cook Medical Inc, Bloomington, IN) between 2013 and 2020 and all endovascular aneurysm repairs performed using Cydar EV Intelligent Maps (Cydar Medical, Cambridge, UK). The Cydar EV cohort was reviewed further to select all FEVARs performed with overlay map guidance. The patient demographic, clinical, and procedure metrics were analyzed, with a comparative analysis of FEVAR performed without and with the Cydar EV imaging platform. Patients were excluded from comparative analysis if the data were incomplete in the dataset or they had a documented history of prior open or endovascular abdominal aortic aneurysm repair.

RESULTS

During the 7-year study period, 191 FEVARs had been performed. The Cydar EV imaging platform was implemented in 2018 and used in 124 complex endovascular aneurysm repairs, including 69 consecutive FEVARs. A complete dataset was available for 137 FEVARs. With exclusion to select for de novo FEVAR, a comparative analysis was performed of 53 FEVAR without and 63 with Cydar EV imaging guidance. The cohorts were similar in patient demographics, medical comorbidities, and aortic aneurysm characteristics. No significant difference was noted between the two groups for major adverse postoperative events, length of stay, or length of intensive care unit stay. The use of Cydar EV resulted in nonsignificant decreases in the mean fluoroscopy time (69.3 ± 28 minutes vs 66.2 ± 33 minutes; P = .598) and operative time (204.4 ± 64 minutes vs 186 ± 105 minutes; P = .278). A statistically significant decrease was found in the iodinated contrast volume (105 ± 44 mL vs 83 ± 32 mL; P = .005), patient radiation exposure using the dose area product (1,049,841 mGy/cm² vs 630,990 mGy/cm²; P < .001) and cumulative air kerma levels (4518 mGy vs 3084 mGy; P = .02) for patients undergoing FEVAR with Cydar EV guidance.

CONCLUSIONS

At our aortic center, we have observed a trend toward shorter operative times and significant reductions in both iodinated contrast use and radiation exposure during FEVAR using the Cydar EV intelligent maps. Intelligent map guidance improved the efficiency of complex endovascular aneurysm repair, providing a safer intervention for both patient and practitioner.

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

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

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Efficacy of Fusion Imaging in Endovascular Revascularization of the Superficial Femoral Artery

BACKGROUND

The demand for endovascular revascularization (ER) to treat peripheral artery disease (PAD) has steadily increased. However, ER comes at the cost of increased contrast and radiation exposure, particularly in more complex cases. Fusion imaging is a new technology that may address these issues. The purpose of this study was to evaluate the efficacy of fusion imaging in ER of the superficial femoral artery (SFA).

METHODS

Patients with PAD undergoing ER of the SFA from February 2016 to July 2020 were retrospectively evaluated. A group of patients treated using fusion imaging was compared with a control group treated without fusion imaging. The primary end points were the contrast dose, fluoroscopy time, radiation dose, and operative time.

RESULTS

A total of 51 patients (fusion group, n = 26; control group, n = 25) underwent ER during the study period. Significantly lower iodinated contrast doses were observed in the fusion than in the control group (56.1 ± 23.7 vs. 87.9 ± 44.9 mL; P = 0.003), as well as significantly shorter fluoroscopy times (21.2 ± 11.1 vs. 44.9 ± 31.4 min; P = 0.001), lower radiation exposure (29.9 ± 8.9 vs. 122.2 ± 223.1 mGy; P = 0.04), and shorter operative times (88.3 ± 32.1 vs. 126.1 ± 66.8 min; P = 0.013).

CONCLUSIONS

The use of fusion imaging technology during ER of the SFA can significantly reduce the contrast dose, fluoroscopy time, radiation dose, and operative time.

Accuracy of registration techniques and vascular imaging modalities in fusion imaging for aortic endovascular interventions: a phantom study

Background

This study aimed to assess the error of different registration techniques and imaging modalities for fusion imaging of the aorta in a standardized setting using a anthropomorphic body phantom.

Materials and methods

A phantom with the 3D printed vasculature of a patient suffering from an infrarenal aortic aneurysm was constructed. Pulsatile flow was generated via an external pump. CTA/MRA of the phantom was performed, and a virtual 3D vascular model was computed. Subsequently, fusion imaging was performed employing 3D-3D and 2D-3D registration techniques. Accuracy of the registration was evaluated from 7 right/left anterior oblique c-arm angulations using the agreement of centerlines and landmarks between the phantom vessels and the virtual 3D virtual vascular model. Differences between imaging modalities were assessed in a head-to-head comparison based on centerline deviation. Statistics included the comparison of means ± standard deviations, student’s t-test, Bland-Altman analysis, and intraclass correlation coefficient for intra- and inter-reader analysis.

Results

3D-3D registration was superior to 2D-3D registration, with the highest mean centerline deviation being 1.67 ± 0.24 mm compared to 4.47 ± 0.92 mm. The highest absolute deviation was 3.25 mm for 3D-3D and 6.25 mm for 2D-3D registration. Differences for all angulations between registration techniques reached statistical significance. A decrease in registration accuracy was observed for c-arm angulations beyond 30° right anterior oblique/left anterior oblique. All landmarks (100%) were correctly positioned using 3D-3D registration compared to 81% using 2D-3D registration. Differences in accuracy between CT and MRI were acceptably small. Intra- and inter-reader reliability was excellent.

Conclusion

In the realm of registration techniques, the 3D-3D method proved more accurate than did the 2D-3D method. Based on our data, the use of 2D-3D registration for interventions with high registration quality requirements (e.g., fenestrated aortic repair procedures) cannot be fully recommended. Regarding imaging modalities, CTA and MRA can be used equivalently.

Automated Image Fusion Guidance during Endovascular Aorto-Iliac Procedures: A Randomized Controlled Pilot Study

BACKGROUND

The benefits of imaging guidance using a new fully automated fusion process (CYDAR) have been demonstrated during endovascular aortic aneurysm repair, but little is known about its use during aorto-iliac occlusive disease endovascular revascularization. The aim of this study was to evaluate the influence of CYDAR image fusion guidance during endovascular treatment of symptomatic aorto-iliac occlusive lesions, compared with control patients treated using standard 2D fluoroscopy alone.

METHODS

This is a single-center randomized controlled pilot study that recruited patients undergoing aorto-iliac endovascular revascularization.

RESULTS

Between January 2019 and February 2020, 37 patients with symptomatic aorto-iliac lesions were enrolled: 18 were assigned to the fusion group and 19 to the control group. Patients and lesions characteristics were well balanced between both study groups. The technical success of the procedure was 100% in the Fusion group and 94% in the control group. All radiation-related parameters were lower in the fusion compared to the control group, including: median DAP 18.5 Gy.cm2 vs. 21.8 Gy.cm2; Air Kerma 0.10 Gy vs. 0.12 Gy; fluoroscopy dose 4.2 Gy.cm² vs. 5.1 Gy.cm²; and number of DSA 7.5 vs. 8. The volume of iodinated contrast used was higher in the fusion group: 41 mL vs. 30 mL. The total procedure time was the same in both groups:60 min vs. 60 min.

CONCLUSIONS

The results of this pilot study suggest the use of fusion imaging in endovascular treatment of aorto-iliac disease results in reduction in radiation-related measured parameters with no change in procedure time and higher doses of iodinated contrast used. These results need to be further investigated in a larger, adequately powered study.

Factors Contributing to an Efficacious Endovascular Treatment for Acute Ischemic Stroke in Asian Population

Although randomized control trials about endovascular treatment (EVT) of emergent large vessel occlusion (LVO) have demonstrated the success of mechanical thrombectomy as the choice of treatment, a wide range of caveats remain unaddressed. Asian patients were rarely included in the trials, thereby raising the question of whether the treatment could be generalized. In addition, there remains a concern on the feasibility of the method with respect to its application against intracranial atherosclerosis (ICAS)-related LVO, frequently observed in the Asian population. It is important to include evidence on ICAS LVO from Asian countries in the future for a comprehensive understanding of LVO etiology. Besides the issues with EVT, prognostic concerns in diabetes patients, acute kidney injury following EVT, neuroprotective management against reperfusion injury, and other peri-EVT issues should be considered in clinical practice. In the current article, we present an in-depth review of the literature that revises information pertaining to such concerns.

Point-of-care creatinine tests to assess kidney function for outpatients requiring contrast-enhanced CT imaging: systematic reviews and economic evaluation

BACKGROUND

Patients with low estimated glomerular filtration rates may be at higher risk of post-contrast acute kidney injury following contrast-enhanced computed tomography imaging. Point-of-care devices allow rapid measurement of estimated glomerular filtration rates for patients referred without a recent estimated glomerular filtration rate result.

OBJECTIVES

To assess the clinical effectiveness and cost-effectiveness of point-of-care creatinine tests for outpatients without a recent estimated glomerular filtration rate measurement who need contrast-enhanced computed tomography imaging.

METHODS

Three systematic reviews of test accuracy, implementation and clinical outcomes, and economic analyses were carried out. Bibliographic databases were searched from inception to November 2018. Studies comparing the accuracy of point-of-care creatinine tests with laboratory reference tests to assess kidney function in adults in a non-emergency setting and studies reporting implementation and clinical outcomes were included. Risk of bias of diagnostic accuracy studies was assessed using a modified version of the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. Probabilities of individuals having their estimated glomerular filtration rates correctly classified were estimated within a Bayesian framework and pooled using a fixed-effects model. A de novo probabilistic decision tree cohort model was developed to characterise the decision problem from an NHS and a Personal Social Services perspective. A range of alternative point-of-care testing approaches were considered. Scenario analyses were conducted.

RESULTS

Fifty-four studies were included in the clinical reviews. Twelve studies reported diagnostic accuracy for estimated glomerular filtration rates; half were rated as being at low risk of bias, but there were applicability concerns for most. i-STAT (Abbott Point of Care, Inc., Princeton, NJ, USA) and ABL (Radiometer Ltd, Crawley, UK) devices had higher probabilities of correctly classifying individuals in the same estimated glomerular filtration rate categories as the reference laboratory test than StatSensor® devices (Nova Biomedical, Runcorn, UK). There was limited evidence for epoc® (Siemens Healthineers AG, Erlangen, Germany) and Piccolo Xpress® (Abaxis, Inc., Union City, CA, USA) devices and no studies of DRI-CHEM NX 500 (Fujifilm Corporation, Tokyo, Japan). The review of implementation and clinical outcomes included six studies showing practice variation in the management decisions when a point-of-care device indicated an abnormal estimated glomerular filtration rate. The review of cost-effectiveness evidence identified no relevant studies. The de novo decision model that was developed included a total of 14 strategies. Owing to limited data, the model included only i-STAT, ABL800 FLEX and StatSensor. In the base-case analysis, the cost-effective strategy appeared to be a three-step testing sequence involving initially screening all individuals for risk factors, point-of-care testing for those individuals with at least one risk factor, and including a final confirmatory laboratory test for individuals with a point-of-care-positive test result. Within this testing approach, the specific point-of-care device with the highest net benefit was i-STAT, although differences in net benefit with StatSensor were very small.

LIMITATIONS

There was insufficient evidence for patients with estimated glomerular filtration rates < 30 ml/minute/1.73 m2, and on the full potential health impact of delayed or rescheduled computed tomography scans or the use of alternative imaging modalities.

CONCLUSIONS

A three-step testing sequence combining a risk factor questionnaire with a point-of-care test and confirmatory laboratory testing appears to be a cost-effective use of NHS resources compared with current practice. The risk of contrast causing acute kidney injury to patients with an estimated glomerular filtration rate of < 30 ml/minute/1.73 m2 is uncertain. Cost-effectiveness of point-of-care testing appears largely driven by the potential of point-of-care tests to minimise delays within the current computed tomography pathway.

FUTURE WORK

Studies evaluating the impact of risk-stratifying questionnaires on workflow outcomes in computed tomography patients without recent estimated glomerular filtration rate results are needed.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42018115818.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 39. See the NIHR Journals Library website for further project information.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

ADVANCES IN KNOWLEDGE

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

Novel diagnostic and imaging techniques in endovascular iliac artery procedures

INTRODUCTION

Endovascular revascularization has become the preferred treatment for most patients with iliac artery obstructions, with a high rate of clinical and technical success.

AREAS COVERED

This review will describe novel developments in the diagnosis and treatment of iliac artery obstructions including the augmentation of preprocedural imaging with advanced flow models, image fusion techniques, and state-of-the-art device-tracking capabilities.

EXPERT OPINION

The combination of these developments will change the endovascular field within the next 5 years, allowing targeted iliac treatment without the need for radiographic imaging or iodinated contrast media.

Endovascular Infrarenal Aortic Aneurysm Repair Performed in a Hybrid Operating Room Versus Conventional Operating Room Using a C-Arm

BACKGROUND

To compare contrast usage and radiation exposure during endovascular aneurysm repair (EVAR) using mobile C-arm imaging in a conventional operating room (OR) or fixed angiographic equipment in a hybrid OR (HR).

METHODS

A retrospective unicenter study from May 2016 to August 2019. All consecutive patients undergoing standard EVAR were included. Patients were divided into 2 groups. Group OR included EVARs performed in a conventional OR with a mobile C-arm (May 2016 to April 2018) and group HR included EVARs performed with a fixed angiographic equipment in an HR (May 2018 to August 2019). Data collected included patient demographics, aneurysm diameter, neck length, radiation dose: median dose-area product (DAP), fluoroscopy time, total operative time, contrast use, and 30-day clinical outcomes.

RESULTS

A total of 77 patients were included in the study (42 patients in group OR and 35 patients in group HR). There was no difference in age, body mass index (BMI), mean aneurysm, and neck length between groups. Patients in the group HR received less contrast volume (108.6 mL [±41.5] vs. 162.5 mL [±52.6]; P < 0.001), but higher radiation dose (154 Gy cm² [±102.9] vs. 61.5 Gy cm² [±42.4]; P < 0.001). There were no differences in fluoroscopy time (20.4 min [±8.5] vs. 23.2 min [±12.4]; P = 0.274) and total operative time (106.4 [±22.3] vs. 109.4 [±25.8]; P = 0.798). No difference was found in terms of 30-day complication rates or operative mortality between groups. DAP was positively correlated with BMI in the group OR (Spearman's rank correlation coefficient r_s, 0.580; P < 0.001), but no correlation could be seen in the group HR (r_s, 0.408; P = 0.028).

CONCLUSIONS

Routine EVAR performed in a hybrid fixed-imaging suite may be associated with less contrast usage, but higher radiation exposure in our center. The significantly higher radiation exposure when the mobile C-arm is replaced by an HR should not be underestimated.

Low-keV virtual monoenergetic imaging reconstructions of excretory phase spectral dual-energy CT in patients with urothelial carcinoma: A feasibility study

OBJECTIVES

To compare objective and subjective image quality between low keV virtual monoenergetic images (VMI) of the excretory phase and conventional venous phase images derived from spectral dual-energy CT (DECT) in the assessment of urothelial carcinoma.

METHODS

26 consecutive patients with histologically confirmed urothelial carcinoma who received clinically indicated venous- and excretory phase abdominal CT scans were included retrospectively. Attenuation, image noise as well as signal- and contrast-to-noise-ratio (SNR, CNR) in venous and excretory phase CT and excretory phase VMI from 40 to 70 keV were obtained from ROI-based measurements in the following regions: urothelial carcinoma, liver, pancreas, renal cortex, subcutaneous fat, renal vein/artery, portal vein, urinary bladder wall, lymph nodes, prostate/uterus. Subjective vessel contrast and delineation of primary tumor manifestations and distant metastases were rated on 5-point Likert scales.

RESULTS

In comparison to venous phase CT, attenuation and SNR in excretory phase VMI40keV were higher (p < 0.001), except for liver parenchyma, where they were comparable (p = 0.07 and p = 0.17, respectively). Regarding image noise, no significant difference was found between venous phase CT and excretory phase VMI40keV (p-range: 0.08-1.00), except for liver, portal vein and renal artery, where it was lower in VMI40keV (p < 0.05). CNR of urothelial carcinoma to circumjacent bladder wall was significantly higher in excretory phase VMI40keV compared to venous phase CT. Subjective vessel contrast and delineation of primary tumor and distant metastases received equivalent or higher Likert scores in excretory phase VMI40keV than in venous phase CT.

CONCLUSION

This feasibility study indicates that in the assessment of urothelial carcinoma, virtual monoenergetic excretory phase images at 40 keV acquired with spectral DECT could be feasible to maintain subjective and objective image quality as provided by conventional venous phase images. Still, equivalence with regards to metastatic lesion detection requires further investigation before employing this technique in a potential signal-scan, single-bolus approach.

Fluoroscopy with MRA fusion image guidance in endovascular iliac artery interventions: study protocol for a randomized controlled trial (3DMR-Iliac-roadmapping study)

BACKGROUND

Endovascular iliac artery interventions rely on the use of two-dimensional digital subtraction angiographies with an iodinated contrast agent and ionizing radiation. The amount of iodinated contrast agent should be limited because of its potentially nephrotoxic effects. Three-dimensional (3D) image fusion requires registration of a preprocedural magnetic resonance angiogram (MRA) or computed tomography (CT) angiogram to a perprocedurally acquired cone-beam CT or two fluoroscopic orthogonal projections. After registration, the 3D angiography images can be overlaid on the fluoroscopy screen and will follow table and C-arm movements. This study will assess the added value of the 3D image fusion technique in iliac artery interventions regarding the amount of the iodinated contrast agent administered.

METHODS/DESIGN

The study cohort will comprise 106 patients (> 18 years) with symptomatic common and/or external iliac artery stenoses or occlusions and a recent (< 6 months) diagnostic MRA from the pelvis through the lower extremities, for which an endovascular intervention is indicated. Patients will be randomized into the control or study group (i.e. treatment without or with 3D image fusion guidance). The primary endpoint is the amount of administered iodinated contrast agent (mL). Secondary outcomes are technical success of the procedure, defined as < 30% residual stenosis over the treated lesion, fluoroscopy time, and radiation dose as dose area product (mGycm2). Patient participation in the study will be completed after hospital discharge.

DISCUSSION

This study is a randomized controlled multicenter trial to provide evidence on the effect of the 3D image fusion technique on the amount of administered iodinated contrast during endovascular common and/or external iliac artery interventions.

TRIAL REGISTRATION

Nederlands Trial Register, NTR5008 . Registered on 16 December 2014.

Assessment of candidate elements for development of spectral photon-counting CT specific contrast agents

Spectral photon-counting computed tomography (SPCCT) is a rapidly emerging imaging modality that provides energy-dependent information on individual x-ray photons, leading to accurate material decomposition and simultaneous quantification of multiple contrast generating materials. Development of SPCCT-specific contrast agents is needed to overcome the issues with currently used iodinated contrast agents, such as difficulty in differentiation from calcified structures, and yield SPCCT’s full promise. In this study, the contrast generation of different elements is investigated using a prototype SPCCT scanner based on a modified clinical CT system and suitable elements for novel contrast agent development for SPCCT imaging are identified. Furthermore, nanoparticles were synthesized from tantalum as a proof of concept spectral photon-counting CT agent and tested for their in vitro cytotoxicity and contrast generation to provide insight into the feasibility of nanoparticle contrast agent development from these elements. We found that gadolinium, ytterbium and tantalum generate high contrast in spectral photon-counting CT imaging and may be suitable elements for contrast agent development for this modality. Our proof of concept results with tantalum-based nanoparticles underscore this conclusion due to their detectability with spectral photon-counting CT, as well as their biocompatibility.

A prospective observational trial of fusion imaging in infrarenal aneurysms

OBJECTIVE

Use of three-dimensional fusion has been shown to significantly reduce radiation exposure and contrast material use in complex (fenestrated and branched) endovascular aneurysm repair (EVAR). Cydar software (CYDAR Medical, Cambridge, United Kingdom) is a cloud-based technology that can provide imaging guidance by overlaying preoperative three-dimensional vessel anatomy from computed tomography scans onto live fluoroscopy images both in hybrid operating rooms and on mobile C-arms. The aim of this study was to determine whether radiation dose reduction would occur with the addition of fusion imaging to infrarenal repair in all imaging environments.

METHODS

All patients who consented to involvement in the trial and who were treated with EVAR in our center from March 2016 until April 2017 were included. A teaching session about radiation protection and Cydar fusion software use was provided to all operators before the start of the fusion group enrollment. This group was compared with a retrospective cohort of patients treated in the same center from March 2015 to March 2016, after a dedicated program of radiation awareness and reduction was introduced. Ruptured aneurysms and complex EVAR were excluded. Preoperative and perioperative characteristics were recorded, including parameters of radiation dose, such as air kerma and dose-area product. Results were expressed in median and interquartile range.

RESULTS

Forty-four patients were prospectively enrolled and compared with 21 retrospective control patients. No significant differences were found in comparing sex, body mass index, and age at repair. The median operation time (wire to wire) and fluoroscopy time were 90 (75-105) minutes and 30 (22-34) minutes, respectively, without significant differences between groups (P = .56 and P = .36). Dose-area product was nonsignificantly higher in the control group, 21.7 (8.9-85.9) Gy cm², compared with the fusion group, 12.4 (7.5-23.4) Gy cm² (P = .10). Air kerma product was significantly higher in the control group, 142 (61-541) mGy, compared with 82 (51-115) mGy in the fusion group (P = .03). The number of digital subtraction angiography runs was significantly lower in the fusion group (8 [6-11]) compared with the control group (10 [9-14]); (P = .03). There were no significant differences in the frequency of adverse events, endoleaks, or additional procedures required.

CONCLUSIONS

When it is used in simple procedures such as infrarenal aneurysm repair, image-based fusion technology is feasible both in hybrid operating rooms and on mobile systems and leads to an overall 50% reduction in radiation dose. Fusion technology should become standard of care for centers attempting to maximize radiation dose reduction, even if capital investment of a hybrid operating room is not feasible.

Editor's Choice - The Implications of Non-compliance to Endovascular Aneurysm Repair Surveillance: A Systematic Review and Meta-analysis

OBJECTIVE/BACKGROUND

Increasingly, reports show that compliance rates with endovascular aneurysm repair (EVAR) surveillance are often suboptimal. The aim of this study was to determine the safety implications of non-compliance with surveillance.

METHODS

The study was carried out according to the Preferred Items for Reporting of Systematic Reviews and Meta-Analyses (PRISMA) guidelines. An electronic search was undertaken by two independent authors using Embase, MEDLINE, Cochrane, and Web of Science databases from 1990 to July 2017. Only studies that analysed infrarenal EVAR and had a definition of non-compliance described as weeks or months without imaging surveillance were analysed. Meta-analysis was carried out using the random-effects model and restricted maximum likelihood estimation.

RESULTS

Thirteen articles (40,730 patients) were eligible for systematic review; of these, seven studies (14,311 patients) were appropriate for comparative meta-analyses of mortality rates. Three studies (8316 patients) were eligible for the comparative meta-analyses of re-intervention rates after EVAR and four studies (12,995 patients) eligible for meta-analysis for abdominal aortic aneurysm related mortality (ARM). The estimated average non-compliance rate was 42.0% (95% confidence interval [CI] 28-56%). Although there is some evidence that non-compliant patients have better survival rates, there was no statistically significant difference in all cause mortality rates (year 1: odds ratio [OR] 5.77, 95% CI 0.74-45.14; year 3: OR 2.28, 95% CI 0.92-5.66; year 5: OR 1.81, 95% CI 0.88-3.74) and ARM (OR 1.47, 95% CI 0.99-2.19) between compliant and non-compliant patients in the first 5 years after EVAR. The re-intervention rate was statistically significantly higher in compliant patients from 3 to 5 years after EVAR (year 1: OR 6.36, 95% CI 0.23-172.73; year 3: OR 3.94, 85% CI 1.46-10.69; year 5: OR 5.34, 95% CI 1.87-15.29).

CONCLUSION

This systematic review and meta-analysis suggests that patients compliant with EVAR surveillance programmes may have an increased re-intervention rate but do not appear to have better survival rates than non-compliant patients.

Lower incidence of contrast-induced nephropathy in patients undergoing fluorescent angiography

Background

To evaluate the incidence and risk factors of contrast-induced nephropathy (CIN) in patients undergoing fluorescein angiography (FA).

Methods

One hundred sixty patients who underwent FA as a part of ophthalmic examination and had serum creatinine (SCr) results within 24 h before FA and within 72 h after FA between 2005 and 2013 at a tertiary medical center were included. According to baseline SCr levels, the subjects were divided into low-risk group (<1.5 mg/dL), intermediate-risk group (1.5–2.0 mg/dL), and high-risk group (>2.0 mg/dL) for CIN development. The CIN incidence, and changes in renal function defined by SCr levels and estimated glomerular filtration rate (eGFR) were evaluated. Demographics and comorbidities were analyzed to investigate an association with CIN development.

Results

Of 160 patients, 91 were males (56.9%). The mean age was 52.46 ± 17.81 years. Two (1.3%) patients developed CIN after FA, whose SCr levels returned to normal within 10 days without hemodialysis. Overall, there were no changes before and after FA in SCr level (1.52 ± 1.31 mg/dL vs. 1.51 ± 1.28 mg/dL, respectively; p = 0.93) and eGFR (67.02 ± 36.62 mL/min/1.73 m² vs. 66.41 ± 36.54 mL/min/1.73 m², respectively; p = 0.54). SCr level and eGFR remained unchanged after FA in low-risk and intermediate-risk groups. In high-risk group, eGFR remined unchanged, but SCr level decreased after FA (from 3.64 ± 1.59 mg/dL to 3.53 ± 1.60 mg/dL; p = 0.04). Basline SCr and cormorbidities did not predict CIN development.

Conclusions

Acute renal function deterioration was not evident in patients undergoing FA regardless of baseline renal function and comorbidities.

A new update for radiocontrast-induced nephropathy aggravated with glycerol in rats: the protective potential of epigallocatechin-3-gallate

Contrast media (CM) is known to have nephrotoxic adverse effects. Epigallocatechin-3-gallate (EGCG) is the most abundant and active catechin in green tea, and has strong antioxidant and anti-inflammatory properties. This study investigated whether EGCG can reduce contrast-induced nephrotoxicity (CIN), alone or with glycerol (GLY)-induced renal damage, and to understand its mechanisms of protection against toxicity, using models of GLY and CIN in rats. The rats were separated into eight groups (n = 6 in each), as follows: Healthy, GLY, CM, GLY + CM, CM + EGCG 50 mg/kg (po), GLY + CM + EGCG 50 mg/kg (po), CM + EGCG 100 mg/kg (po), and GLY + CM + EGCG 100 mg/kg (po). Both doses of EGCG protected against CM-induced renal dysfunction, as measured by serum creatinine and blood urea nitrogen (BUN). In addition, EGCG treatment markedly improved CIN-induced oxidative stress, and resulted in a significant down-regulatory effect on tumor necrosis factor (TNF)-α and nuclear factor (NF)-κB mRNA expression. Moreover, histopathological analysis showed that EGCG also attenuated CM-induced kidney damage. Considering the potential clinical use of CM and the numerous health benefits of EGCG, this study showed the protective role of multi-dose EGCG treatment on CIN and GLY-aggravated CIN through different mechanisms.

Gold silver alloy nanoparticles (GSAN): an imaging probe for breast cancer screening with dual-energy mammography or computed tomography

Earlier detection of breast cancer reduces mortality from this disease. As a result, the development of better screening techniques is a topic of intense interest. Contrast-enhanced dual-energy mammography (DEM) is a novel technique that has improved sensitivity for cancer detection. However, the development of contrast agents for this technique is in its infancy. We herein report gold-silver alloy nanoparticles (GSAN) that have potent DEM contrast properties and improved biocompatibility. GSAN formulations containing a range of gold : silver ratios and capped with m-PEG were synthesized and characterized using various analytical methods. DEM and computed tomography (CT) phantom imaging showed that GSAN produced robust contrast that was comparable to silver alone. Cell viability, reactive oxygen species generation and DNA damage results revealed that the formulations with 30% or higher gold content are cytocompatible to Hep G2 and J774A.1 cells. In vivo imaging was performed in mice with and without breast tumors. The results showed that GSAN produce strong DEM and CT contrast and accumulated in tumors. Furthermore, both in vivo imaging and ex vivo analysis indicated the excretion of GSAN via both urine and feces. In summary, GSAN produce strong DEM and CT contrast, and has potential for both blood pool imaging and for breast cancer screening.

Improved sensitivity of computed tomography towards iodine and gold nanoparticle contrast agents via iterative reconstruction methods

Computed tomography is a widely used medical imaging technique that has high spatial and temporal resolution. Its weakness is its low sensitivity towards contrast media. Iterative reconstruction techniques (ITER) have recently become available, which provide reduced image noise compared with traditional filtered back-projection methods (FBP), which may allow the sensitivity of CT to be improved, however this effect has not been studied in detail. We scanned phantoms containing either an iodine contrast agent or gold nanoparticles. We used a range of tube voltages and currents. We performed reconstruction with FBP, ITER and a novel, iterative, modal-based reconstruction (IMR) algorithm. We found that noise decreased in an algorithm dependent manner (FBP > ITER > IMR) for every scan and that no differences were observed in attenuation rates of the agents. The contrast to noise ratio (CNR) of iodine was highest at 80 kV, whilst the CNR for gold was highest at 140 kV. The CNR of IMR images was almost tenfold higher than that of FBP images. Similar trends were found in dual energy images formed using these algorithms. In conclusion, IMR-based reconstruction techniques will allow contrast agents to be detected with greater sensitivity, and may allow lower contrast agent doses to be used.

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.

Compliance of postendovascular aortic aneurysm repair imaging surveillance

OBJECTIVE

Imaging surveillance after endovascular aortic aneurysm repair (EVAR) is critical. In this study we analyzed compliance with imaging surveillance after EVAR and its effect on clinical outcomes.

METHODS

Retrospective analysis of prospectively collected data of 565 EVAR patients (August 2001-November 2013), who were followed using duplex ultrasound and/or computed tomography angiography. Patients were considered noncompliant (NC) if they did not have any follow-up imaging for 2 years and/or missed their first post-EVAR imaging over 6 months. A Kaplan-Meier analysis was used to compare compliance rates in EVAR patients with hostile neck (HN) vs favorable neck (FN) anatomy (according to instructions for use). A multivariate analysis was also done to correlate compliance and comorbidities.

RESULTS

Forty-three percent were compliant (7% had no follow-up imaging) and 57% were NC. The mean follow-up for compliant patients was 25.4 months (0-119 months) vs 31.4 months for NC (0-140 months). The mean number of imaging was 3.5 for compliant vs 2.6 for NC (P < .0001). Sixty-four percent were NC for HN patients vs 50% for FN patients (P = .0007). The rates of compliance at 1, 2, 3, 4, and 5 years for all patients were 78%, 63%, 55%, 45%, and 32%; and 84%, 68%, 61%, 54%, and 40% for FN patients; and 73%, 57%, 48%, 37%, and 25% for HN patients (P = .009). The NC rate for patients with late endoleak and/or sac expansion was 58% vs 54% for patients with no endoleak (P = .51). The NC rate for patients with late reintervention was 70% vs 53% for patients with no reintervention (P = .1254). Univariate and multivariate analyses showed that patients with peripheral arterial disease had an odds ratio of 1.9 (P = .0331), patients with carotid disease had an odds ratio of 2 (P = .0305), and HN patients had an odds ratio of 1.8 (P = .0007) for NC. Age and residential locations were not factors in compliance.

CONCLUSIONS

Overall, compliance of imaging surveillance after EVAR was low, particularly in HN EVAR patients, and additional studies are needed to determine if strict post-EVAR surveillance is necessary, and its effect on long-term clinical outcome.

Urgent endovascular repair for ruptured aortic aneurysm using computed tomography image fusion

Abdominal aortic aneurysm rupture remains a cardiovascular catastrophe with strikingly high morbidity and mortality rates. Endovascular aneurysm repair management has recently emerged as a valuable treatment modality for ruptured abdominal aortic aneurysm, but better outcomes have to be reached. Image fusion may potentially improve perioperative outcomes in selected patients, guiding navigation and device implantation and limiting contrast dosage during interventions. We report an 83-year-old man presenting with an 80-mm infrarenal aortic aneurysm rupture suitable for endovascular aneurysm repair. Endovascular navigation and stent graft deployment were achieved using computed tomography image fusion for the first reported case in English.

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.

Image fusion performed with noncontrast computed tomography scans during endovascular aneurysm repair

We report two endovascular aneurysm repair procedures achieved under image fusion guidance accomplished with noncontrast injected preoperative computed tomography scans. Such use of this advanced imaging application reduces contrast media injection volume (respectively, 27 and 24 mL throughout the patients' hospital course). No changes in creatinine clearance occurred after the procedures. Contrast-enhanced ultrasound imaging confirmed technical success in both cases.

Tnf-α inhibition by infliximab as a new target for the prevention of glycerol-contrast-induced nephropathy

Contrast medium-induced nephropathy (CIN) remains as a problem with high incidence and mortality rates. The aim of this study is to examine the roles of infliximab (INF) in the glycerol (GLY) and CIN model in rats. The rats were separated into five groups (n=8): Healthy, GLY, GLY+CM, GLY+CM+INF 5mg/kg intraperitoneally (i.p.), and GLY+CM+INF 7 mg/kg (i.p.). Antioxidant levels in the therapy groups were observed to be quite similar to those in the healthy group. In this study, while the kidney TNF-α, IL-1β, TGF-1β and Caspase 3 gene expressions' levels increased in the nephrotoxic groups, these levels were found to have decreased in the treatment groups. Moreover, histopathologic examination showed that hyaline, haemorrhagic casts and necrosis were increased in nephrotoxicity group, whereas they decreased in the therapy group. Furthermore, TNF-α and NF-κB expression were decreased with infliximab administrated groups similar to control group. In conclusion, we suggest that infliximab have protective roles on CIN.

3D contrast enhancement-MR angiography for imaging of unruptured cerebral aneurysms: a hospital-based prevalence study

Background and Purpose

Contrast enhanced MRA (CE-MRA) can help to overcome the limitations of other techniques to clearly display the details of cerebral aneurysms at 1.5-T MR system. We investigated the prevalence of unruptured cerebral aneurysms (UCAs) using three dimensional (3D) CE-MRA in a tertiary comprehensive hospital in China.

Materials and Methods

The cases were prospectively recorded at our hospital between February 2009 and October 2010. 3D CE-MRA, interpreted by 2 observers blinded to the participants’ information, was used to identify the location and size of UCAs and to estimate the overall, age-specific, and sex-specific prevalence.

Results

Of the 3993 patients (men: women = 2159∶1834), 408 UCAs were found in 350 patients (men: women = 151∶199). The prevalence was 8.8% overall (95% CI, 8.0–10.0%), with 7.0% for men (CI, 6.0–8.0%) and 10.9% for women (CI, 9.0–12.0%). The overall prevalence of UCAs was higher in women than in men (P<0.001) and increased with age both in men and women. Prevalence peaked at age group 75–80 years. Forty-two patients (11.7%) had multiple aneurysms, including 10 (2.9%) male patients and 32 (9.1%) female patients. The most common site of aneurysm was the carotid siphon, and most lesions (71.3%) had a maximum diameter of 3−5 mm.

Conclusion

This hospital-based prevalence study suggested a high prevalence (8.8%) of UCAs and most lesions (71.3%) had a maximum diameter of 3–5 mm observed by 3D CE-MRA. Because the rupture of small cerebral aneurysms was not uncommon, an appropriate follow-up care strategy must be formulated.

Computed tomography scans with intravenous contrast: low incidence of contrast-induced nephropathy in blunt trauma patients

BACKGROUND

Computed tomography (CT) with intravenous (IV) contrast is an important step in the evaluation of the blunt trauma patient; however, the risk for contrast-induced nephropathy (CIN) in these patients still remains unclear. The goal of this study was to describe the rate of CIN in blunt trauma patients at a Level 1 trauma center and identify the risk factors of developing CIN.

METHODS

After internal review board approval, we reviewed our Level 1 trauma registry to identify blunt trauma patients admitted during a 1-year period. Chart review was used to identify patient demographics, creatinine levels, and vital signs. CIN was defined as an increase in creatinine by 0.5 mg/dL from admission after undergoing CT with IV contrast.

RESULTS

Four percent of patients developed CIN during their admission following receipt of IV contrast for CT; 1% had continued renal impairment on discharge. No patients required dialysis during their admission. Diabetic patients had an increased rate of CIN, with 10% rate of CIN during admission and 4% at discharge. In multivariate analysis, only preexisting diabetes and Injury Severity Score (ISS) of greater than 25 were independently associated with risk for CIN.

CONCLUSION

The rate of CIN in trauma patients following CT scan with IV contrast is low. Diabetes and ISS were independent risk factors of development of CIN in trauma patients.

LEVEL OF EVIDENCE

Epidemiologic/prognostic study, level III.

Plasma exogenous creatinine clearance in clinically healthy cats: comparison with urinary exogenous creatinine clearance, tentative reference intervals and indexation to bodyweight

Glomerular filtration rate (GFR) is considered to be the best indicator of overall kidney function. The major objectives of this study were to compare plasma exogenous creatinine clearance (PECC) with a reference method, to establish reference intervals (RIs) for PECC and to assess the effects of indexation of GFR to bodyweight (BW) in cats. PECC was compared with urinary clearance of exogenous creatinine (UECC) in six clinically healthy domestic shorthair cats (experiment 1). Tentative RIs were determined according to current guidelines and the effects of indexation to BW and of covariables on GFR were assessed in 43 clinically healthy cats of various breeds (experiment 2). PECC was 15% higher than UECC (P <0.01), but the two estimates were strongly correlated (r(2)=0.97, P = 0.001). RIs for PECC were 6.4-21.3 mL/min or 1.2-4.9 mL/min/kg. The absolute (i.e. non-indexed) GFR value was not dependent on BW. Thus, indexation of GFR to BW in cats would not standardize the GFR value, but could introduce bias in clinical interpretation. Significant effects of breed, plasma protein concentration and plasma albumin concentration on GFR were demonstrated. Plasma concentrations of urea and creatinine, when assessed separately, were also weakly correlated with GFR in healthy cats. These combined findings contribute to a better understanding of renal function assessment in cats.

Brain natriuretic peptide for prevention of contrast-induced nephropathy after percutaneous coronary intervention or coronary angiography

BACKGROUND

Many methods reportedly prevent contrast-induced nephropathy (CIN), but the effect of brain natriuretic peptide (BNP) on CIN is unknown. In this study we investigated recombinant BNP use before coronary angiography (CA) or nonemergent percutaneous coronary intervention (PCI) in patients with unstable angina.

METHODS

One thousand patients with unstable angina were prospectively evaluated. The patients were randomly assigned to: group A, isotonic normal saline (NaCl 0.9%, 1 mL/kg/h) for 24 hours before CA or PCI; and group B, human recombinant BNP (rhBNP; 0.005 μg/kg/min). Serum creatinine (Scr) levels and estimated glomerular filtration rate were measured before and 24, 48, and 72 hours, and 7 days after the procedure. The primary outcome was CIN incidence defined according to a relative (≥ 25%) or absolute (≥ 0.5 mg/dL and 44 μmol/L, respectively) increase in Scr from baseline within 48 hours. The secondary end points were the changes in the Scr and estimated glomerular filtration rate, before and after the procedure.

RESULTS

Contrast volume, a history of diabetes mellitus, and BNP administration independently predicted CIN. The incidence of CIN was significantly greater in group A than in group B (14.8% vs 5.6%; P < 0.01). Renal function was less compromised in patients who received rhBNP. The Scr of all patients with CIN remained increased for 24 hours, but it was lower and recovered faster in patients who received rhBNP.

CONCLUSIONS

rhBNP administration before CA or PCI protects renal function and can significantly decrease CIN incidence.

Evaluation of disproportionality safety signaling applied to healthcare databases

OBJECTIVE

To evaluate the performance of a disproportionality design, commonly used for analysis of spontaneous reports data such as the FDA Adverse Event Reporting System database, as a potential analytical method for an adverse drug reaction risk identification system using healthcare data.

RESEARCH DESIGN

We tested the disproportionality design in 5 real observational healthcare databases and 6 simulated datasets, retrospectively studying the predictive accuracy of the method when applied to a collection of 165 positive controls and 234 negative controls across 4 outcomes: acute liver injury, acute myocardial infarction, acute kidney injury, and upper gastrointestinal bleeding.

MEASURES

We estimate how well the method can be expected to identify true effects and discriminate from false findings and explore the statistical properties of the estimates the design generates. The primary measure was the area under the curve (AUC) of the receiver operating characteristic (ROC) curve.

RESULTS

For each combination of 4 outcomes and 5 databases, 48 versions of disproportionality analysis (DPA) were carried out and the AUC computed. The majority of the AUC values were in the range of 0.35 < AUC < 0.6, which is considered to be poor predictive accuracy, since the value AUC = 0.5 would be expected from mere random assignment. Several DPA versions achieved AUC of about 0.7 for the outcome Acute Renal Failure within the GE database. The overall highest DPA version across all 20 outcome-database combinations was the Bayesian Information Component method with no stratification by age and gender, using first occurrence of outcome and with assumed time-at-risk equal to duration of exposure + 30 d, but none were uniformly optimal. The relative risk estimates for the negative control drug-event combinations were very often biased either upward or downward by a factor of 2 or more. Coverage probabilities of confidence intervals from all methods were far below nominal.

CONCLUSIONS

The disproportionality methods that we evaluated did not discriminate true positives from true negatives using healthcare data as they seem to do using spontaneous report data.

Automatically Recognizing Medication and Adverse Event Information From Food and Drug Administration's Adverse Event Reporting System Narratives

Background

The Food and Drug Administration’s (FDA) Adverse Event Reporting System (FAERS) is a repository of spontaneously-reported adverse drug events (ADEs) for FDA-approved prescription drugs. FAERS reports include both structured reports and unstructured narratives. The narratives often include essential information for evaluation of the severity, causality, and description of ADEs that are not present in the structured data. The timely identification of unknown toxicities of prescription drugs is an important, unsolved problem.

Objective

The objective of this study was to develop an annotated corpus of FAERS narratives and biomedical named entity tagger to automatically identify ADE related information in the FAERS narratives.

Methods

We developed an annotation guideline and annotate medication information and adverse event related entities on 122 FAERS narratives comprising approximately 23,000 word tokens. A named entity tagger using supervised machine learning approaches was built for detecting medication information and adverse event entities using various categories of features.

Results

The annotated corpus had an agreement of over .9 Cohen’s kappa for medication and adverse event entities. The best performing tagger achieves an overall performance of 0.73 F1 score for detection of medication, adverse event and other named entities.

Conclusions

In this study, we developed an annotated corpus of FAERS narratives and machine learning based models for automatically extracting medication and adverse event information from the FAERS narratives. Our study is an important step towards enriching the FAERS data for postmarketing pharmacovigilance.

Pathogenesis of renal failure in multiple myeloma: any role of contrast media?

The spectrum of kidney disease-associated monoclonal immunoglobulin and plasma cell malignancies is remarkably broad and encompasses nearly all nephropathologic entities. Multiple myeloma with kidney impairment at presentation is a medical emergency since the recovery of kidney function is associated with survival benefits. In most cases, kidney impairment may be the first clinical manifestation of malignant plasma cell dyscrasias like multiple myeloma and light chain amyloidosis. Multiple myeloma per se cannot be considered a main risk factor for developing acute kidney injury following intravascular administration of iodinated contrast media. The risk is increased by comorbidities such as chronic kidney disease, diabetes, hypercalcemia, dehydration, and use of nephrotoxic drugs. Before the administration of contrast media, the current recommended laboratory tests for assessing kidney function are serum creatinine measurement and the estimation of glomerular filtration rate by using the CKD-EPI equation. The assessment of Bence Jones proteinuria is unnecessary for evaluating the risk of kidney failure in patients with multiple myeloma, since this test cannot be considered a surrogate biomarker of kidney function.

Ascorbic Acid for the prevention of contrast-induced nephropathy after coronary angiography in patients with chronic renal impairment: a randomized controlled trial

To determine the incidence of contrast-induced nephropathy (CIN) and to assess the effectiveness of ascorbic acid in the prevention of CIN after coronary angiography in patients with chronic renal impairment. CIN is the third most common cause of hospital-acquired renal failure. It is well documented that periprocedural hydration is effective in the prevention of CIN. Little data exist on the effectiveness of ascorbic acid, a vitamin with antioxidative action. Patients with stable serum creatinine level >107 μmol/L (n = 81) undergoing coronary angiography were randomized to receive either ascorbic acid (N = 40) or placebo (N = 41) before the procedure. All patients received intravenous volume expansion with normal saline before the procedure. CIN was defined as an increase of serum creatinine level >25% from baseline measured 3 to 4 days after the procedure. CIN occurred totally in 5/81 patients (6.2%); in two patients (3%) in the ascorbic acid group and in three patients (7.3%) in the placebo group (P = 0.512). Postprocedural worsening of renal function (postprocedural increase of serum creatinine level) was present in 10/81 patients (12.3%) in the ascorbic acid group and in 19/81 patients (23.4%) in the placebo group (P = 0.038). No patient required dialysis treatment. We found no statistically significant impact of ascorbic acid on the incidence of CIN in patients with chronic renal impairment undergoing coronary arteriography or angioplasty. Ascorbic acid may still have some protective role in CIN reflected in lower incidence of worsening of renal function in the treated group.

Radiographic contrast-media-induced acute kidney injury: pathophysiology and prophylactic strategies

Contrast-induced acute kidney injury (CI-AKI) is one of the most widely discussed and debated topics in cardiovascular medicine. With increasing number of contrast-media- (CM-) enhanced imaging studies being performed and growing octogenarian population with significant comorbidities, incidence of CI-AKI remains high. In this review, pathophysiology of CI-AKI, its relationship with different types of CM, role of serum and urinary biomarkers for diagnosing CI-AKI, and various prophylactic strategies used for nephroprotection against CI-AKI are discussed in detail.

Radiation dose and image quality at high-pitch CT angiography of the aorta: intraindividual and interindividual comparisons with conventional CT angiography

OBJECTIVE

The objective of our study was to evaluate radiation dose and quantitative image quality parameters at high-pitch CT angiography (CTA) of the aorta compared with conventional CTA.

MATERIALS AND METHODS

We studied the examinations of 110 patients (65 men and 45 women; mean age ± SD, 64 ± 15 years) who had undergone CTA of the entire aorta on a second-generation dual-source CT system; 50 examinations were performed in high-pitch mode. The mean arterial attenuation, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and figure of merit (FOM) were calculated for the high-pitch CTA and conventional CTA groups. Radiation exposures were compared.

RESULTS

All studies were considered of diagnostic quality. At high-pitch CTA, the mean tube voltage and tube current-exposure time product were 118 ± 7 kV (SD) and 197 ± 78 mAs compared with 120 ± 1 kV and 258 ± 78 mAs, respectively, at conventional CTA (p < 0.05). The mean volume CT dose index, dose-length product, and effective dose were 8.1 ± 2.4 mGy, 561.1 ± 178.6 mGy × cm, and 9.6 ± 3.0 mSv at high-pitch CTA and 18.3 ± 7.7 mGy, 1162.6 ± 480.1 mGy × cm, and 19.8 ± 8.2 mSv at conventional CTA (p < 0.001). Attenuation was similar for both protocols, whereas significantly less contrast medium was injected for high-pitch CTA than for standard-pitch CTA (87.3 ± 16 mL vs 97.9 ± 16 mL, respectively; p < 0.01). The SNR and CNR were significantly lower in the high-pitch CTA examinations (p < 0.01), whereas the FOM was nonsignificantly higher. Twenty patients underwent both high-pitch CTA and conventional CTA, with a 45% reduction in radiation dose (p < 0.001).

CONCLUSION

High-pitch CTA of the aorta yields 45-50% reduction of radiation exposure as well as contrast medium savings with maintained vessel attenuation.

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.

Frequency of acute kidney injury following intravenous contrast medium administration: a systematic review and meta-analysis

PURPOSE

To perform a systematic review and meta-analysis of controlled studies examining the incidence of acute kidney injury (AKI) and other outcomes in patients exposed to intravenous (i.v.) contrast medium compared with patients who underwent an imaging examination without contrast medium or were otherwise unexposed (control group).

MATERIALS AND METHODS

MEDLINE, EMBASE, Scopus, and the Cochrane Library were searched for all articles published through September 2011 that contained search terms related to nephrotoxicity following intravenous contrast medium administration. Two independent reviewers identified studies in which the incidence of AKI in patients exposed to i.v. contrast medium was directly compared with the incidence of AKI in unexposed patients through analysis of changes in serum creatinine level or estimated glomerular filtration rate 48-72 hours following imaging procedures or admission. Study characteristics and outcomes of AKI, dialysis, and mortality were extracted by using a standardized protocol. Relative risk (RR) was calculated by using random-effects models and was tested in subgroups of different patient comorbidities, contrast medium types, and AKI diagnostic criteria. RR results of less than 1.00 indicated that there was a higher incidence of these outcomes in the group that did not receive contrast medium (non-contrast medium group).

RESULTS

Of the 1489 studies originally identified, 13 nonrandomized studies (0.9%) representing 25,950 patients met inclusion criteria. In the group that received contrast medium (contrast medium group), risk of AKI (RR = 0.79; 95% confidence interval [CI]: 0.62, 1.02; P = .07), death (RR = 0.95; 95% CI: 0.55, 1.67; P = .87), and dialysis (RR = 0.88; 95% CI: 0.23, 3.43; P = .85) was similar, compared with the risk of AKI in the non-contrast medium group. This pattern was observed regardless of i.v. contrast medium type, diagnostic criteria for AKI, or whether patients had diabetes mellitus or renal insufficiency.

CONCLUSION

Controlled contrast medium-induced nephropathy studies demonstrate a similar incidence of AKI, dialysis, and death between the contrast medium group and control group.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12121460/-/DC1.