Carbon dioxide angiography for endovascular grafting in high-risk patients with infrarenal abdominal aortic aneurysms

Peroperative Intravascular Ultrasound for Endovascular Aneurysm Repair versus Peroperative Angiography: A Pilot Study in Fit Patients with Favorable Anatomy

BACKGROUND

The aim of this study was to compare intravascular ultrasound (IVUS) assistance for endovascular aortic aneurysm repair (EVAR) to standard assistance by angiography.

METHODS

From June 2015 to June 2017, 173 consecutive patients underwent EVAR. In this group, 69 procedures were IVUS-assisted with X-ray exposure limited to completion angiography for safety purposes because an IVUS probe does not yet incorporate a duplex probe (group A), and 104 were angiography-assisted procedures (group B). All IVUS-assisted procedures were performed by vascular surgeons with basic duplex ultrasound (DUS) training. The primary study endpoints were mean radiation dose, duration of fluoroscopy, amount of contrast media administered, procedure-related outcomes, and renal clearance expressed as the glomerular filtration rate (GFR) before and after the procedure. Secondary endpoints were operative mortality, morbidity, and arterial access complications.

RESULTS

Mean duration of fluoroscopy time was significantly lower for IVUS-assisted procedures (24 ± 15 min vs. 40 ± 30 min for angiography-assisted procedures, P < 0.01). Moreover, mean radiation dose (Air KERMA) was significantly lower in IVUS-assisted procedures (76m Gy [44-102] vs. 131 mGy [58-494]), P < 0.01. IVUS-assisted procedures required fewer contrast media than standard angiography-assisted procedures (60 ± 20 mL vs. 120 ± 40 mL, P < 0.01). The mean duration of the procedure was comparable in the two groups (120 ± 30 min vs. 140 ± 30 min, P = 0.07). No difference in renal clearance before and after the procedure was observed in either of the two groups (99.0 ± 4/97.8 ± 2 mL/min in group A and 98.0 ± 3/97.6 ± 5 mL/min in group B) (P = 0.28). The mean length of follow-up was nine months (6-30 months). No postoperative mortality, morbidity, or arterial access complications occurred. No type 1 endoleak was observed. Early type II endoleaks were observed in 21 patients (11%), 12 in the angiography-assisted group (11%) and nine in the IVUS-assisted group (12%). They were not associated with sac enlargement ≥5 mm diameter and therefore did not require any additional treatment.

CONCLUSIONS

Compared with standard angiography-assisted EVAR, IVUS significantly reduces renal load with contrast media, fluoroscopy time, and radiation dose while preserving endograft deployment efficiency. Confirmation from a large prospective study with improved IVUS probes will be required before IVUS-assisted EVAR alone can become standard practice.

The Assessment of Carbon Dioxide Automated Angiography in Type II Endoleaks Detection: Comparison with Contrast-Enhanced Ultrasound

Introduction

Iodinated contrast media completion angiography (ICM-A) may underestimate the presence of type II endoleak (ELII) after endovascular aortic repair (EVAR), particularly if they are at low flow. Contrast-enhanced ultrasound (CEUS) has been proposed as the gold standard in ELII detection during EVAR follow-up. Intraprocedural carbon dioxide (CO₂) angiography has been shown to be useful in this setting; however no comparative studies including these three techniques are currently available. Our aim was to investigate the accuracy of a new automated CO₂ angiographic (CO₂-A) system in the detection of ELII, by comparing it with ICM-A and CEUS.

Methods

A series of consecutive patients undergoing EVAR for abdominal aortic aneurysm (AAA) were enrolled and submitted to ICM-A and CO₂-A during the procedure. The iodinated contrast media were delivered through an automatic injector connected to a pigtail catheter in the suprarenal aorta. CO₂ was delivered through a recently available automatic injector connected to a 10 F sheath positioned in the external iliac artery. All patients were blindly evaluated by CEUS within postoperative day 1. The ICM-A and CO₂-A ability to detect ELII was compared with that of CEUS through Cohen's concordance Index (K).

Results

Twenty-one patients were enrolled in the study. One (5%), seven (33%), and four (19%) ELII were detected by ICM-A, CO₂-A, and CEUS, respectively. The only ELII detected by ICM-A was also detected by CO₂-A and CEUS. Three cases of ELII detected by CO₂-A were not detected by CEUS. All ELII detected by CEUS were visualized by CO₂-A. CEUS and ICM-A showed a poor agreement (Cohen's K: 0.35) while CEUS and CO₂-A showed a substantial agreement (Cohen's K: 0.65) for ELII detection.

Conclusion

CO₂-A is safe and effective method for ELII detection in EVAR, with a significantly higher agreement with CEUS if compared with ICM-A. This trial is registered with 155/2015/U/Oss.

Computerized tomography angiography by direct intra-aortic low volume contrast injection in patients being evaluated for EVAR

Background Computerized tomography angiography is an important tool for endovascular repair of abdominal aortic aneurysm planning. This study aimed to evaluate the utility of computerized tomography angiography using direct intra-aortic injection of low volume of iodinated contrast in patients being considered for endovascular repair of abdominal aortic aneurysm. Design A 5F high-flow angiographic catheter was positioned in the mid-thoracic aorta through femoral percutaneous access. Computerized tomography angiography was performed with image acquisition starting simultaneously with power injection of 10 mL of iopamidol 76% diluted with normal saline to 50 mL, at 6 mL/s through the angiographic catheter. Aortic enhancement was assessed with a circular region-of-interest within the aorta. Values ≥150 HU were considered adequate. Results Nine patients with abdominal aortic aneurysm and chronic renal dysfunction underwent computerized tomography angiography with intra-arterial contrast injection for endovascular repair of abdominal aortic aneurysm planning. Mean age 78.8 ± 5.0 years, mean baseline creatinine 1.8 ± 0.4 mg/dL and mean glomerular filtration rate 36.8 ± 4.2 mL/min. Adequate computerized tomography angiography aortic enhancement was obtained in all cases (mean intra-aortic density: 300.4 ± 72.8 HU). The total contrast volume used for the computerized tomography angiography and the endovascular repair of abdominal aortic aneurysm combined was 30.0 ± 21.4 mL. Seventy-five percent of the patients received ≤30 mL of contrast. No significant renal function deterioration occurred (creatinine clearance pre- and post-procedure 36.8 ± 4.2 mL/min versus 38.6 ± 6.1 mL/min, p = 0.32). Successful endovascular repair of abdominal aortic aneurysm was achieved in eight patients. One patient underwent open treatment based on computerized tomography angiography information. No endoleak or aneurysm growth occurred (median follow-up: 121 days (range 36-1242)). Conclusion Direct intra-aortic injection of low volume of iodinated contrast provides adequate and reproducible pattern of aortic enhancement on computerized tomography angiography. The computerized tomography angiography so acquired can be used for endovascular repair of abdominal aortic aneurysm limiting the total volume of iodinated contrast required.

A Novel Bubble-Mixture Method to Improve Dynamic Images in Carbon Dioxide Angiography

Purpose: To present a novel method of preparing carbon dioxide (CO2) for contrast enhancement.Technique: CO2 angiography can often produce poor image enhancement, especially in dependent vessels due to buoyancy of the gas. A new technique for premixing the CO2 gas with the patient’s blood and dispersing it into the bubble mixture before injection was developed. Comparative dynamic images showed bubble-mixed CO2 angiography had less fragmentation, more even distribution, and more sustainability than the same volume of pure CO2. Conclusion: The alteration of CO2 gas toward a semiliquid form demonstrates an easy and reproducible concept to improve the dynamic image quality of traditional CO2 angiography.

Carbon dioxide digital subtraction angiography as an option for detection of endoleaks in endovascular abdominal aortic aneurysm repair procedure

OBJECTIVE

The purpose of this study was to evaluate carbon dioxide digital subtraction angiography (CO2-DSA) as an option for the detection of endoleaks (ELs) in the endovascular abdominal aortic aneurysm repair (EVAR) procedure.

METHODS

Forty patients with abdominal aortic aneurysm who were scheduled to undergo EVAR were enrolled in the study. There were 35 men and five women (mean age, 77.9 years). All patients had both iodinated contrast conventional DSA (C-DSA) and CO2-DSA immediately after EVAR. The sensitivity and specificity were calculated for the ability of CO2-DSA to detect ELs. We also correlated with computed tomography findings 6 months after EVAR.

RESULTS

C-DSA showed that 27 of the 40 patients (68%) had 28 ELs (type I, four; type II, 20; type III, three; type IV, one). CO2-DSA showed that 16 of the 40 patients (40%) had 17 ELs (type I, four; type II, 10; type III, three; type IV, none). For the prediction of direct ELs (type I and type III) with use of C-DSA as the criterion standard, CO2-DSA has a sensitivity of 1.0 and a specificity of 1.0. For the detection of persistent type II ELs (n = 11) with use of computed tomography findings 6 months from EVAR as the criterion standard, CO2-DSA has a sensitivity of 0.87 and a specificity of 0.97. C-DSA has a sensitivity of 0.82 and a specificity of 0.64.

CONCLUSIONS

CO2-DSA is reliable for the detection of direct ELs and persistent type II ELs in EVAR. CO2-DSA can be an option to detect ELs in the EVAR procedure.

Considerations for patients undergoing endovascular abdominal aortic aneurysm repair

Endovascular aneurysm repair has taken over open surgery as the primary strategy for treatment of patients with abdominal and thoracic aneurysms. The minimally invasive nature of these techniques requires alterations in preoperative workup, intraoperative management, and familiarity with unique complications that can occur. Familiarity from the anesthetic standpoint of endovascular techniques, including treatment of patients with fenestrated, chimney, snorkel, and periscope grafts, is necessary for the contemporary cardiac anesthesiologist.

A prospective study of carbon dioxide digital subtraction versus standard contrast arteriography in the detection of endoleaks in endovascular abdominal aortic aneurysm repairs

BACKGROUND

The objective of this study is to compare intraoperative endoleak detection by carbon dioxide digital subtraction angiography (CO(2)-DSA) during endovascular aortic aneurysm repair (EVAR) with standard iodinated contrast angiography (ICA).

METHODS

Between 2006 and 2010, 76 patients with abdominal aortic aneurysms undergoing EVAR were enrolled in a prospective study. After EVAR, both an ICA and CO(2)-DSA completion study were performed. Two blinded vascular surgeons who were not involved with the EVAR separately interpreted the ICA and CO(2)-DSA results for the presence or absence of an endoleak. Identified endoleaks were classified by types. A third, "tie-breaker" blinded observer was used to resolve differences in interpretations. The sensitivity, specificity, negative predictive value, and positive predictive value were calculated for the ability of CO(2)-DSA to detect endoleaks. Cohen's κ statistic was used to assess interobserver agreement between the 2 initial interpreting surgeons.

RESULTS

Of the 76 patients undergoing EVAR, 66 were men with average age of 76 years, a mean aneurysm size of 5.8 cm (range, 4-10 cm), and creatinine of 1 (standard deviation, 0.33). ICA identified 35 type I and 15 type II endoleaks, respectively, while CO(2)-DSA identified 40 type I and 10 type II endoleaks. Overall, CO(2)-DSA had a sensitivity of 0.84, specificity of 0.72, positive predictive value of 0.86, and negative predictive value of 0.69 of intraoperative endoleak detection, with respect to ICA as the criterion standard. The interobserver κ between surgeons for ICA was 0.56, for detection of any endoleak or type I endoleak with CO(2)-DSA was 0.58, and for detection of type II endoleak with CO(2)-DSA was 0.29.

CONCLUSIONS

Interobserver agreement for the detection of endoleaks is superior with ICA compared to CO(2)-DSA. However, the sensitivity for detecting any endoleak and both the sensitivity and specificity for detecting type I endoleaks using CO(2)-DSA are acceptable. For detecting type II endoleaks using CO(2)-DSA, the sensitivity and positive predictive value are poor. Compared to ICA, CO(2)-DSA provides adequate images for endoleak detection during EVAR and is an acceptable alternative to ICA in patients at risk for contrast-related nephrotoxicity.

Complications after endovascular aneurysm repair

Endovascular aneurysm repair (EVAR) has become an established technique for the treatment of many infrarenal aortic aneurysms. Although EVAR is obviously less invasive than open surgical repair, it is not free of complications. These can potentially result in severe morbidity or even mortality, stressing the need for an early detection and subsequent treatment. In this review article, the pathophysiology, diagnosis, and treatment of the most common complications of EVAR, with the exception of endoleaks, are described.

First experience using intraoperative contrast-enhanced ultrasound during endovascular aneurysm repair for infrarenal aortic aneurysms

BACKGROUND

Endovascular aortic repair (EVAR) has become an additional treatment option for patients with infrarenal aortic aneurysms and suitable aortic morphology. However, endoleaks are commonly encountered and represent a relevant risk for secondary treatment failure. In addition, impaired renal function or allergic reactions to intravascular iodine application might represent exclusion criteria for conventional infrarenal endovascular aortic repair using intraoperative angiography with iodine contrast media. Real-time contrast-enhanced ultrasound (CEUS) with a low mechanical index (MI) is a promising method recently introduced for follow up after endovascular infrarenal aortic repair.

METHODS

In this study, intraoperative CEUS using SonoVue as ultrasound contrast agent was evaluated in 17 patients for localization of the proximal infrarenal landing zone, the distal iliac fixation area, and identification of endoleaks in patients suitable for endovascular aortic repair with an infrarenal aortic neck > or =10 mm and non-aneurysmal common iliac arteries. For comparison, 20 patients were treated by conventional EVAR using intraoperative fluoroscopy and iodine contrast media.

RESULTS

Intraoperative application of contrast-enhanced ultrasound (iCEUS) for identification of the infrarenal landing zone and proximal stent graft release was achieved in 14 out of 17 patients (82.4%), as verified by intraoperative angiography or postinterventional imaging. Intraoperative CEUS-assisted visualization of the distal fixation area proximal to the level of the iliac bifurcation was achieved in 89.3% (25 out of 28 iliac arteries examined) in comparison to intraoperative angiography or postinterventional CEUS, computed tomography (CT), or magnetic resonance (MR) angiography. Three selected patients having contraindications for iodine-based contrast media were treated by iCEUS-assisted EVAR without the use of any iodine contrast during fluoroscopy. Time for exposure to intraoperative radiation, volume of contrast medium used, and the number of intraoperative angiographies and postinterventional CT or MR angiographies were significantly reduced in the iCEUS-assisted EVAR group in comparison to conventional endovascular aortic treatment (P < .002 or less for all parameters). Intraoperative application of CEUS detected more endoleaks than conventional EVAR (8/17 vs 4/20; P = .08) treated by proximal stent graft extension in one symptomatic patient with a type Ia endoleak.

CONCLUSIONS

Intraoperative CEUS-assisted EVAR in patients with infrarenal aortic aneurysms represents a new option for intraoperative visualization of aortoiliac segments required as proximal or distal fixation zones and identification of endoleaks, especially in those patients with contraindications for usage of iodine-containing contrast agents, in association with a reduction of iodine contrast media used and radiation exposure during fluoroscopy.

An evaluation of the use of carbon dioxide angiography in endovascular aortic aneurysm repair

INTRODUCTION

Renal dysfunction after endovascular aortic aneurysm repair is an increasingly recognised problem. Carbon dioxide (CO(2)) angiography has been used to limit the risk of contrast nephrotoxicity during endovascular procedures. This prospective study evaluates the performance of CO(2) angiography during EVAR.

METHODS

Seventeen patients undergoing EVAR over a 12 month period were included. All were males with a median age of 74 (range 62-86) years. The median preoperative creatinine was 105 (range 77-165) micromol/L. CO(2) angiography was used routinely in all patients for graft positioning. Contrast was used for completion angiograms and whenever CO(2) did not satisfactorily demonstrate the anatomy.

RESULTS

All patients had successful deployment of stent graft. The median contrast usage was 59 (range 20-250)ml. CO( 2) angiography successfully demonstrated the aortic and iliac bifurcation in all 17 cases and the renal artery anatomy in 9. 7 out of 17 patients had both CO(2) and contrast completion angiography. CO(2) correlated with contrast angiography in 6 of the 7 patients. There was no significant difference in pre and post-operative creatinine values (P >0.9; Wilcoxon test).

CONCLUSION

CO(2) angiography is a useful adjunct to contrast during the performance of EVAR and helps reduce contrast load and the risk of contrast nephrotoxicity.

Catheter-less angiography for endovascular aortic aneurysm repair: a new application of carbon dioxide as a contrast agent

OBJECTIVE

Avoidance of nephrotoxic contrast agents during endovascular repair of abdominal aortic aneurysms (EVAR) may reduce the incidence of renal dysfunction following the procedure. Carbon dioxide (CO(2)) angiography is a safe alternative to iodinated contrast media vastly under-utilized by vascular surgeons. We herein describe our experience with a simple angiographic technique using CO(2) for EVAR guidance that does not require a separate angiographic catheter.

METHODS

Eighteen patients underwent EVAR using angiography with CO(2) delivered through the endograft sheath. The renal and hypogastric arteries were localized for endograft deployment exclusively with CO(2) in all patients. Completion angiography was done with CO(2) in all patients and an additional angiogram with iodinated media was done in 13 cases.

RESULTS

All endograft deployments were done successfully with CO(2) angiography injected through the endograft delivery systems and femoral access sheaths. Additional iodinated media completion angiography did not modify the procedure in any case. All patients were discharged within two days after surgery. There were no ischemic or systemic complications related to CO(2) administration. Follow-up CT-scan revealed well positioned endografts with the expected patent renal and hypogastric arteries in all patients, and no additional endoleaks. No significant deterioration in renal function occurred in any case.

CONCLUSION

Carbon dioxide angiography conducted through the endograft delivery sheath is reliable for endograft deployment, safe, non-toxic and inexpensive. In addition, it may expedite EVAR by eliminating a number of angiographic catheter placements and exchanges during the procedure. This favorable experience warrants further utilization of this technique.

Carbon dioxide digital subtraction angiography-assisted endovascular aortic aneurysm repair in the azotemic patient

OBJECTIVE

This report analyzes the safety and efficacy of carbon dioxide digital subtraction angiography (CO(2)-DSA) for EVAR in a group of patients with renal insufficiency compared with a concurrent group of patients with normal renal function undergoing EVAR with iodinated contrast angiography (ICA).

METHODS

Between 2003 and 2005, 100 consecutive patients who underwent EVAR using ICA, CO(2)-DSA, or both were retrospectively reviewed, and preoperative, intraoperative, postoperative, and follow-up variables were collected. Patients were divided into two groups depending on renal function and contrast used. Group I comprised patients with normal renal function in whom ICA was used exclusively, and group II patients had a serum creatinine >or=1.5 mg/dL, and CO(2)-DSA was used preferentially and supplemented with ICA, when necessary. The two groups were compared for the outcomes of successful graft placement, renal function, endoleak type, and frequency, and the need for graft revision. Comparisons were made using chi(2) analysis, Student t test, and the Fisher exact test.

RESULTS

A total of 84 EVARs were performed in group I and 16 in group II. Patient demographics and risk factors were similar between groups with the exception of serum creatinine, which was significantly increased in group II (1.8 mg/dL vs 1.0 mg/dL P < .0005). All 100 endografts were successfully implanted. Patients in group II had longer fluoroscopy times, longer operative times, and increased radiation exposure, and 13 of 16 patients required supplemental ICA. Mean iodinated contrast use was 27 mL for group II vs 148 mL in group I (P < .0005). Mean postoperative serum creatinine was unchanged from baseline, and 30-day morbidity was similar for both groups. No patient required dialysis. No patients died. Perioperatively, and at 1 and 6 months, the endoleak type and incidence and need for endograft revision was no different between groups.

CONCLUSIONS

CO(2)-DSA is safe, can be used to guide EVAR, and provides outcomes similar to ICA-guided EVAR. CO2-DSA protects renal function in the azotemic patient by lessening the need for iodinated contrast and associated nephrotoxicity, but with the tradeoff of longer fluoroscopy and operating room times and increased radiation exposure.

The Current Status of the Use of Carbon Dioxide in Diagnostic and Interventional Angiographic Procedures

Since the first description of carbon dioxide (CO(2)) angiography the indications for using CO(2) have been changing and the applications of CO(2) angiography evolving. This review covers the contemporary role of CO(2) angiography. CO(2) angiography can be considered according to whether it is likely to be better, equivalent to or worse than conventional iodinated contrast medium (ICM). Areas where CO(2) angiography offers distinct advantages over ICM will be emphasized. The limitations to using CO(2) and specific caveats will be discussed. The basic physical properties of CO(2) and avoidance of the complications of gas angiography will be considered. CO(2) gas is cheap, non-allergenic, and is not nephrotoxic. Unfortunately it is not a panacea, angiographic quality is reduced, it is not tolerated by every patient, and it cannot be used in every location. It is important to be pragmatic and to use conventional contrast or alternative imaging rather than struggling with suboptimal CO(2) angiography.

Estudo angiográfico de fístula arteriovenosa utilizando gás carbônico como meio de contrante

OBJETIVO: Este estudo tem por finalidade obter um método diagnóstico angiográfico alternativo que possa ser utilizado em doentes com alto risco ao uso de meio de contraste iodado. MATERIAIS E MÉTODOS: Foram estudados 26 doentes com insuficiência renal crônica, que tiveram suas fístulas analisadas, submetidos à angiografia digital - na primeira fase, utilizando o meio de contraste iodado e, na segunda fase, gás carbônico como meio de contraste, com registro em filme angiográfico. A angiografia foi avaliada por dois médicos independentes, que analisaram a opacificação, o diagnóstico radiológico e o calibre dos vasos; a análise comparativa das medidas da artéria, da veia e da freqüência respiratória antes e após a injeção de contraste foi realizada pelo autor. RESULTADOS: Os resultados obtidos pela analise estatística utilizando coeficiente kappa apresentaram concordância entre os dois médicos, referente à opacificação, de 0,3217, referente ao diagnóstico radiológico, de 0,5583, e referente à analise de calibre dos vasos, de 0,4298. A análise das medidas da artéria e da veia não apresentou diferença significativa pela medida de posição e dispersão, mostrando concordância na regressão linear, com p-valor de 0,3657 e de 0,2041; para a freqüência respiratória, as análises das medidas de posição e dispersão não apresentaram diferença significativa. CONCLUSÃO: Concluímos ser este método uma alternativa no estudo angiográfico em pacientes com antecedente alérgico ou com risco nefrotóxico.

Comparison of carbon dioxide and iodinated contrast for cavography prior to inferior vena cava filter placement

BACKGROUND

The use of iodinated contrast in the critically ill trauma patient has been associated with the development of acute renal failure. The low incidence of nephrotoxicity associated with carbon dioxide (CO(2)) makes it an ideal contrast agent for cavography. However, the use of CO(2) has been limited, because reportedly it underestimates the diameter of the inferior vena cava (IVC).

METHODS

During a 6-month period (January 2000 through June 2000), 25 adult trauma patients required IVC filter placement. Bedside cavagrams using CO(2) followed by iodinated contrast were employed to determine the diameter of the IVC and the anatomy of the renal veins.

RESULTS

Using CO(2) injection for cavography, we were able to determine the diameter of the IVC and the anatomy of the renal veins in all patients. Furthermore, when CO(2) cavography was compared with the results obtained with iodinated contrast, the difference in diameter of the IVC was within 1 mm.

CONCLUSIONS

Based on these data, it was determined that CO(2) cavagrams accurately reflect the diameter of the IVC and the anatomy of the renal veins. Additionally, CO(2) cavagrams can be safely performed in the intensive care unit during bedside placement of IVC filters.

Endovascular aortic aneurysm repair in patients with renal dysfunction or severe contrast allergy: utility of imaging modalities without iodinated contrast

Contrast-enhanced imaging studies are required for preoperative evaluation in patients undergoing endovascular aortic aneurysm repair; however, the use of iodinated contrast agents may not be suitable in patients with renal dysfunction or severe contrast allergy. The objective of this study was to evaluate the utility of imaging modalities without iodinated contrast in patients undergoing endovascular aortic aneurysm repair. A total of 297 patients underwent endo vascular repair of abdominal aortic aneurysms during a 6-year period ending in August 2001. Among them, 20 patients (6.2%), who underwent imaging studies without iodinated contrast because of either renal dysfunction or severe contrast allergy formed the basis of this study. Multiple non-iodinated contrast imaging studies were used, including gadolinium-enhanced magnetic resonance angiography (MRA), non-contrast computed tomography (CT), gadolinium or carbon dioxide (CO2) aortography, and intravascular ultrasound (IVUS). Hospital records were reviewed to evaluate the imaging study, renal function, perioperative morbidity, and clinical outcome of endo vascular aortic aneurysm repair. From the results of our study we concluded that endovascular aortic aneurysm repair can be performed safely in patients with renal dysfunction or severe contrast allergy utilizing non-iodinated contrast-based imaging modalities. IVUS is a useful intraoperative imaging modality, and postoperative endoleak surveillance can be performed using duplex ultrasound scanning to avoid risk of iodinated contrast exposure.