Duplex Ultrasound Scanning is Reliable in the Detection of Endoleak Following Endovascular Aneurysm Repair

Colour Duplex and/or Contrast-Enhanced Ultrasound Compared with Computed Tomography Angiography for Endoleak Detection after Endovascular Abdominal Aortic Aneurysm Repair: A Systematic Review and Meta-Analysis

This study aims to assess the role of Color Duplex Ultrasound with or without contrast media for surveillance following endovascular aortic aneurysm repair (EVAR). A systematic search of the literature published until April 2022 was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The pooled rates of endoleak detection through Contrast-Enhanced or Color Duplex Ultrasound (CEUS or CDUS) and Computed Tomography Angiography (CTA) with 95% confidence intervals (CIs) were estimated using random-effect analysis. Thirty-eight studies were considered eligible for inclusion. The total number of patients in the included studies was 5214 between 1997 and 2021. The overall pooled rate of endoleak detection using CDUS and CTA was 82.59% and 97.22%, while the rates for CEUS and CTA were 96.67% and 92.82%, respectively. The findings of the present study support the use of the CEUS for endoleak detection. However, it should be integrated into institutional protocols for EVAR surveillance to further evaluate its clinical utility in the post-EVAR period before it can be recommended as the sole imaging modality after EVAR.

Color Doppler ultrasound for surveillance following EVAR as the primary tool

OBJECTIVE

As aneurysm-related events and rupture is not eliminated, postoperative lifelong surveillance is mandatory after endovascular aneurysm repair (EVAR). For surveillance colored Doppler ultrasound (CDUS) is a standard method of noninvasive evaluation having the advantages of availability, cost-effectiveness, and lack of nephrotoxicity and radiation. We evaluated CDUS for primary surveillance tool after elective EVAR by comparing with computerized tomography.

METHODS

Between January 2018 and March 2020, 84 consecutive post-EVAR patients were evaluated. First, CDUS was performed by two Doppler operators from the Radiology Department and then computed tomographic angiography (CTA) was performed. The operators were blind to CTA reports. A reporting protocol was organized for endoleak detection and largest aneurysm diameter.

RESULTS

Among 84 patients, there were 11 detected endoleaks (13.1%) with CTA and seven of them was detected with CDUS (r = .884, p < .001). All Type I and III endoleaks were detected perfectly. There is an insufficiency in detecting low flow by CDUS. Eliminating this frailty, there was a strong correlation of aneurysm sac diameter measurement between CTA and CDUS (r = .777, p < .001). The sensitivity and specificity of CDUS was 63.6% and 100%, respectively. The accuracy was 95.2%. Positive and negative predictive values were 100% and 94.8%. Bland-Altman analysis and linear regression analysis showed no proportional bias (mean difference of 1.5 ± 2.2 mm, p = .233).

CONCLUSIONS

For surveillance, CDUS promises accurate results without missing any potential complication requiring intervention as Type I or III endoleak. Lack of detecting Type II endoleaks may be negligible as sac enlargement was the key for reintervention in this situation and CDUS has a remarkably high correlation with CTA in sac diameter measurement. CDUS may be a primary surveillance tool for EVAR and CTA will be reserved in case of aneurysm sac enlargement, detection of an endoleak, inadequate CDUS, or in case of unexplained abdominal symptomatology. By this way we not only avoid ionizing radiation and nephrotoxic agents, but also achieve cost saving issue also.

Diagnostic Colour Duplex Ultrasound for Type IIIb Endoleak

Introduction

This report presents the treatment of an aortic endovascular aneurysm repair (EVAR) device failure, focusing on the use of colour duplex ultrasound (CDUS) to diagnose and confirm effective treatment of a type IIIb endoleak.

Report

An 89 year old man with a history of EVAR was transferred to the authors’ centre with complaints of abdominal pain and a pressure sensation behind the umbilicus. A previously stable 11 cm aneurysm sac was visualised on computed tomography angiography in addition to a newly suspected type IIIb endoleak, which was confirmed via CDUS. He underwent successful endovascular repair with a stent across the limb defect. The patient was discharged uneventfully and was followed for surveillance.

Discussion

Type IIIb endoleak is an underreported complication after EVAR. CDUS of type IIIb endoleak aided in localisation and characterisation of the graft failure, and confirmed successful endovascular treatment of the endoleak defect in the side limb. Locating the point of graft failure using CDUS preceding endovascular repair of type IIIb endoleaks guides interventions and repair outcomes. It is a rare opportunity to report a case of acute type IIIb endoleak with CDUS that definitively localised an endograft defect.

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Safe, economic, and effective surveillance is imperative after EVAR.

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Colour duplex ultrasound should be considered in the preoperative period to characterise the endoleak.

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Colour duplex ultrasound can quantify flow velocity and direction in the setting of endoleak.

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Colour duplex ultrasound may be used to confirm appropriate treatment of endoleak.

Contrast-enhanced ultrasound and/or colour duplex ultrasound for surveillance after endovascular abdominal aortic aneurysm repair: a systematic review and economic evaluation

BACKGROUND

Endovascular abdominal aortic aneurysm repair (EVAR) of abdominal aortic aneurysm (AAA) is less invasive than open surgery, but may be associated with important complications. Patients receiving EVAR require long-term surveillance to detect abnormalities and direct treatments. Computed tomography angiography (CTA) has been the most common imaging modality adopted for EVAR surveillance, but it is associated with repeated radiation exposure and the risk of contrast-related nephropathy. Colour duplex ultrasound (CDU) and, more recently, contrast-enhanced ultrasound (CEU) have been suggested as possible, safer, alternatives to CTA.

OBJECTIVES

To assess the clinical effectiveness and cost-effectiveness of imaging strategies, using either CDU or CEU alone or in conjunction with plain radiography, compared with CTA for EVAR surveillance.

DATA SOURCES

Major electronic databases were searched, including MEDLINE, EMBASE, Science Citation Index, Scopus' Articles-in-Press, Cochrane Central Register of Controlled Trials (CENTRAL), Database of Abstracts of Reviews of Effects (DARE) and NHS Economic Evaluation Database from 1996 onwards. We also searched for relevant ongoing studies and conference proceedings. The final searches were undertaken in September 2016.

METHODS

We conducted a systematic review of randomised controlled trials and cohort studies of patients with AAAs who were receiving surveillance using CTA, CDU and CEU with or without plain radiography. Three reviewers were involved in the study selection, data extraction and risk-of-bias assessment. We developed a Markov model based on five surveillance strategies: (1) annual CTA; (2) annual CDU; (3) annual CEU; (4) CDU together with CTA at 1 year, followed by CDU on an annual basis; and (5) CEU together with CTA at 1 year, followed by CEU on an annual basis. All of these strategies also considered plain radiography on an annual basis.

RESULTS

We identified two non-randomised comparative studies and 25 cohort studies of interventions, and nine systematic reviews of diagnostic accuracy. Overall, the proportion of patients who required reintervention ranged from 1.1% (mean follow-up of 24 months) to 23.8% (mean follow-up of 32 months). Reintervention was mainly required for patients with thrombosis and types I-III endoleaks. All-cause mortality ranged from 2.7% (mean follow-up of 24 months) to 42% (mean follow-up of 54.8 months). Aneurysm-related mortality occurred in < 1% of the participants. Strategies based on early and mid-term CTA and/or CDU and long-term CDU surveillance were broadly comparable with those based on a combination of CTA and CDU throughout the follow-up period in terms of clinical complications, reinterventions and mortality. The economic evaluation showed that a CDU-based strategy generated lower expected costs and higher quality-adjusted life-year (QALYs) than a CTA-based strategy and has a 63% probability of being cost-effective at a £30,000 willingness-to-pay-per-QALY threshold. A CEU-based strategy generated more QALYs, but at higher costs, and became cost-effective only for high-risk patient groups.

LIMITATIONS

Most studies were rated as being at a high or moderate risk of bias. No studies compared CDU with CEU. Substantial clinical heterogeneity precluded a formal synthesis of results. The economic model was hindered by a lack of suitable data.

CONCLUSIONS

Current surveillance practice is very heterogeneous. CDU may be a safe and cost-effective alternative to CTA, with CTA being reserved for abnormal/inconclusive CDU cases.

FUTURE WORK

Research is needed to validate the safety of modified, more-targeted surveillance protocols based on the use of CDU and CEU. The role of radiography for surveillance after EVAR requires clarification.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016036475.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

The Society for Vascular Surgery practice guidelines on follow-up after vascular surgery arterial procedures

Although follow-up after open surgical and endovascular procedures is generally regarded as an important part of the care provided by vascular surgeons, there are no detailed or comprehensive guidelines that specify the optimal approaches with regard to testing methods, indications for reintervention, and follow-up intervals. To provide guidance to the vascular surgeon, the Clinical Practice Council of the Society for Vascular Surgery appointed an expert panel and a methodologist to review the current clinical evidence and to develop recommendations for follow-up after vascular surgery procedures. For those procedures for which high-quality evidence was not available, recommendations were based on observational studies, committee consensus, and indirect evidence. Recognizing that there are numerous published reports on the role of duplex ultrasound for surveillance of infrainguinal vein bypass grafts, the Society commissioned a systematic review and meta-analysis on this topic. The panel classified the strength of each recommendation and the corresponding quality of evidence on the basis of the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system: recommendations were graded either strong or weak, and the quality of evidence was graded high, moderate, or low. The resulting recommendations represent a wide variety of open surgical and endovascular procedures involving the extracranial carotid artery, thoracic and abdominal aorta, mesenteric and renal arteries, and lower extremity arterial revascularization. The panel also identified many areas in which there was a lack of high-quality evidence to support their recommendations. This suggests that there are opportunities for further clinical research on testing methods, threshold criteria, and the role of surveillance as well as on the modes of failure and indications for reintervention after vascular surgery procedures.

Ultrasonography for endoleak detection after endoluminal abdominal aortic aneurysm repair

BACKGROUND

People with abdominal aortic aneurysm who receive endovascular aneurysm repair (EVAR) need lifetime surveillance to detect potential endoleaks. Endoleak is defined as persistent blood flow within the aneurysm sac following EVAR. Computed tomography (CT) angiography is considered the reference standard for endoleak surveillance. Colour duplex ultrasound (CDUS) and contrast-enhanced CDUS (CE-CDUS) are less invasive but considered less accurate than CT.

OBJECTIVES

To determine the diagnostic accuracy of colour duplex ultrasound (CDUS) and contrast-enhanced-colour duplex ultrasound (CE-CDUS) in terms of sensitivity and specificity for endoleak detection after endoluminal abdominal aortic aneurysm repair (EVAR).

SEARCH METHODS

We searched MEDLINE, Embase, LILACS, ISI Conference Proceedings, Zetoc, and trial registries in June 2016 without language restrictions and without use of filters to maximize sensitivity.

SELECTION CRITERIA

Any cross-sectional diagnostic study evaluating participants who received EVAR by both ultrasound (with or without contrast) and CT scan assessed at regular intervals.

DATA COLLECTION AND ANALYSIS

Two pairs of review authors independently extracted data and assessed quality of included studies using the QUADAS 1 tool. A third review author resolved discrepancies. The unit of analysis was number of participants for the primary analysis and number of scans performed for the secondary analysis. We carried out a meta-analysis to estimate sensitivity and specificity of CDUS or CE-CDUS using a bivariate model. We analysed each index test separately. As potential sources of heterogeneity, we explored year of publication, characteristics of included participants (age and gender), direction of the study (retrospective, prospective), country of origin, number of CDUS operators, and ultrasound manufacturer.

MAIN RESULTS

We identified 42 primary studies with 4220 participants. Twenty studies provided accuracy data based on the number of individual participants (seven of which provided data with and without the use of contrast). Sixteen of these studies evaluated the accuracy of CDUS. These studies were generally of moderate to low quality: only three studies fulfilled all the QUADAS items; in six (40%) of the studies, the delay between the tests was unclear or longer than four weeks; in eight (50%), the blinding of either the index test or the reference standard was not clearly reported or was not performed; and in two studies (12%), the interpretation of the reference standard was not clearly reported. Eleven studies evaluated the accuracy of CE-CDUS. These studies were of better quality than the CDUS studies: five (45%) studies fulfilled all the QUADAS items; four (36%) did not report clearly the blinding interpretation of the reference standard; and two (18%) did not clearly report the delay between the two tests.Based on the bivariate model, the summary estimates for CDUS were 0.82 (95% confidence interval (CI) 0.66 to 0.91) for sensitivity and 0.93 (95% CI 0.87 to 0.96) for specificity whereas for CE-CDUS the estimates were 0.94 (95% CI 0.85 to 0.98) for sensitivity and 0.95 (95% CI 0.90 to 0.98) for specificity. Regression analysis showed that CE-CDUS was superior to CDUS in terms of sensitivity (LR Chi² = 5.08, 1 degree of freedom (df); P = 0.0242 for model improvement).Seven studies provided estimates before and after administration of contrast. Sensitivity before contrast was 0.67 (95% CI 0.47 to 0.83) and after contrast was 0.97 (95% CI 0.92 to 0.99). The improvement in sensitivity with of contrast use was statistically significant (LR Chi² = 13.47, 1 df; P = 0.0002 for model improvement).Regression testing showed evidence of statistically significant effect bias related to year of publication and study quality within individual participants based CDUS studies. Sensitivity estimates were higher in the studies published before 2006 than the estimates obtained from studies published in 2006 or later (P < 0.001); and studies judged as low/unclear quality provided higher estimates in sensitivity. When regression testing was applied to the individual based CE-CDUS studies, none of the items, namely direction of the study design, quality, and age, were identified as a source of heterogeneity.Twenty-two studies provided accuracy data based on number of scans performed (of which four provided data with and without the use of contrast). Analysis of the studies that provided scan based data showed similar results. Summary estimates for CDUS (18 studies) showed 0.72 (95% CI 0.55 to 0.85) for sensitivity and 0.95 (95% CI 0.90 to 0.96) for specificity whereas summary estimates for CE-CDUS (eight studies) were 0.91 (95% CI 0.68 to 0.98) for sensitivity and 0.89 (95% CI 0.71 to 0.96) for specificity.

AUTHORS' CONCLUSIONS

This review demonstrates that both ultrasound modalities (with or without contrast) showed high specificity. For ruling in endoleaks, CE-CDUS appears superior to CDUS. In an endoleak surveillance programme CE-CDUS can be introduced as a routine diagnostic modality followed by CT scan only when the ultrasound is positive to establish the type of endoleak and the subsequent therapeutic management.

Treatment of Abdominal Aortic Pathology

Abdominal aortic pathology is a diverse topic, ranging through a broad span of possible pathologies. The treatment options are equally vast, particularly with the ever-expanding endovascular techniques. In this article, we discuss management strategies for abdominal aortic aneurysms and aortic occlusive disease, because they represent some of the most common pathologies encountered in clinical scenarios.

Outcomes Following Limb Crossing in Endovascular Aneurysm Repairs

Background:

Crossing the limbs of the stent during endovascular aneurysm repair (EVAR) is often used to aid cannulation of the contralateral limb. This study assessed outcomes following the use of this technique.

Methods:

Retrospective review of crossed (n = 43) and uncrossed (n = 269) EVARs was performed at a tertiary vascular center over 5 years. Primary end points were graft limb occlusion (GLO), endoleak, and sac expansion rates. Indications for limb crossing were also assessed.

Results:

Two-year GLO ( P = .34) and type 1 endoleak ( P = .413) rates were similar between groups. Patients undergoing crossed EVAR experienced more type 2 endoleaks ( P = .002) at 24 months but no increase in sac expansion rates was observed ( P = .275). Thirty-day ( P = .57) and late ( P = .268) mortalities were similar between groups. The main indication for limb crossing was distal aortic angulation (48.8%).

Conclusions:

Crossed EVAR does not increase the risk of GLOs or clinically significant endoleaks. Further studies are needed to determine the effect on type 2 endoleak rates.

Duplex Ultrasound versus Computed Tomography for the Postoperative Follow-Up of Endovascular Abdominal Aortic Aneurysm Repair. Where Do We Stand Now?

In the last decade, endovascular aneurysm repair (EVAR) has rapidly developed to be the preferred method for infrarenal abdominal aortic aneurysm repair in patients with suitable anatomy. EVAR offers the advantage of lower perioperative mortality and morbidity but carries the cost of device-related complications such as endoleak, graft migration, graft thrombosis, and structural graft failure. These complications mandate a lifelong surveillance of EVAR patients and their endografts. The purpose of this study is to review and evaluate the safety of color-duplex ultrasound (CDU) as compared with computed tomography (CT), based on the current literature, for post-EVAR surveillance. The post-EVAR follow-up modalities, CDU versus CT, are evaluated questioning three parameters: (1) accuracy of aneurysm size, (2) detection and classification of endoleaks, and (3) detection of stent-graft deformation. Studies comparing CDU with CT scan for investigation of post-EVAR complications have produced mixed results. Further and long-term research is needed to evaluate the efficacy of CDU versus CT, before CDU can be recommended as the primary imaging modality for EVAR surveillance, in place of CT for stable aneurysms.

Vascular ultrasonography for follow-up of endovascular repair of abdominal aorta aneurysms

BackgroundThere is little information available on follow-up of abdominal aortic aneurysm patients treated with endovascular repair using vascular ultrasonography in Brazil or on how it compares with the results of angiotomography. Since ultrasonography is an examination that is risk-free, inexpensive and widely available, it is a very attractive method. In this study we attempted to evaluate the sensitivity and specificity of vascular ultrasonography for follow-up of these patients by comparing the method with angiotomography.Materials and methodsWe conducted a prospective study from June 2012 to May 2013. We examined patients followed-up at the endovascular surgery clinic run by the University Hospital of Londrina after endovascular repair of abdominal aortic aneurysms. All patients underwent angiotomography for follow-up and were also examined using simple abdominal X-rays and vascular ultrasonography.ResultsA total of 30 patients were analyzed, with a mean age of 73 years and a mean aneurysm diameter of 6 cm. Four endoleaks were detected. Vascular ultrasonography achieved sensitivity of 75% and specificity of 96% for classification of these endoleaks, in comparison with angiotomography.ConclusionsVascular ultrasonography is an excellent primary method for evaluation and post-surgical follow-up of patients treated with endovascular repair of abdominal aorta aneurysms. However, when ultrasonography detects problems or is difficult to accomplish, it should be supplemented with a more specific investigation for diagnostic confirmation.

Surveillance of Endovascular Aneurysm Repair: An Audit of Sonographer-Led Ultrasound and Radiologist-Led Computed Tomography Services

Objectives

Postoperative complications associated with endovascular aneurysm repair (EVAR) mandate the need for lifelong surveillance. The aim of this audit was to compare the detection rates of endoleaks during the first 10 months of a combined sonographer-led colour Doppler ultrasound (CDUS) and radiologist-led contrast-enhanced computed tomography (CECT), postoperative EVAR surveillance programme, within a single National Health Service Hospital.

Methods

A prospective audit was carried out of all patients with EVAR, who had same-day CECT and CDUS surveillance examinations between March 2010 and January 2011. CECT examinations were reported by three consultant vascular radiologists. Of 66 CDUS examinations, 64 (97%) were performed and reported by four certified vascular sonographers. The reports of dual-modality, same-day scans were compared, to establish agreement on the presence and classification of the type, or absence of endoleaks. CECT was used as the gold standard, against which the sensitivity and specificity of CDUS in endoleak detection was determined.

Results

Sixty-six paired same-day CECT and CDUS reports were compared. Ten endoleaks were identified by CECT (15% incidence) and eight (80%) of 10 were type II. The number of observed agreements was 58 (88%) of 66; CDUS missed six endoleaks (five type II) and suggested two false-positives. CDUS had a sensitivity of 40% and a specificity of 96%. Conclusions: In our study, CDUS demonstrated an excellent specificity but had a low sensitivity for endoleak detection. We agree CDUS cannot effectively replace CECT as the sole imaging modality. Research to determine an international consensus for an effective and efficient postoperative EVAR surveillance patient pathway is required.

Systematic review and meta-analysis of duplex ultrasonography, contrast-enhanced ultrasonography or computed tomography for surveillance after endovascular aneurysm repair

BACKGROUND

Previous analyses suggested that duplex ultrasonography (DUS) detected endoleaks after endovascular aneurysm repair (EVAR) with insufficient sensitivity; they did not specifically examine types 1 and 3 endoleak, which, if untreated, may lead to aneurysm-related death. In light of changes to clinical practice, the diagnostic accuracy of DUS and contrast-enhanced ultrasonography (CEUS) for types 1 and 3 endoleak required focused reappraisal.

METHODS

Studies comparing DUS or CEUS with computed tomography (CT) for endoleak detection were identified. CT was taken as the standard in bivariable meta-analysis.

RESULTS

Twenty-five studies (3975 paired scans) compared DUS with CT for all endoleaks. The pooled sensitivity was 0·74 (95 per cent confidence interval 0·62 to 0·83) and the pooled specificity was 0·94 (0·90 to 0·97). Thirteen studies (2650 paired scans) reported detection of types 1 and 3 endoleak by DUS; the pooled sensitivity of DUS was 0·83 (0·40 to 0·97) and the pooled specificity was 1·00 (0·97 to 1·00). Eleven studies (961 paired scans) compared CEUS with CT for all endoleaks. The pooled sensitivity of CEUS was 0·96 (0·85 to 0·99) and the pooled specificity was 0·85 (0·76 to 0·92). Eight studies (887 paired scans) reported detection of types 1 and 3 endoleak by CEUS. The pooled sensitivity of CEUS was 0·99 (0·25 to 1·00) and the pooled specificity was 1·00 (0·98 to 1·00).

CONCLUSION

Both CEUS and DUS were specific for detection of types 1 and 3 endoleak. Estimates of their sensitivity were uncertain but there was no evidence of a clinically important difference. DUS detects types 1 and 3 endoleak with sufficient accuracy for surveillance after EVAR.

Use of colour duplex ultrasound as a first line surveillance tool following EVAR is associated with a reduction in cost without compromising accuracy

INTRODUCTION

CT scanning remains the postoperative surveillance imaging modality of choice following EVAR. Concerns regarding cost, exposure to ionising radiation and intravenous contrast have led to a search for a less expensive, equally efficacious and safer method of monitoring EVAR patients after endograft deployment. This study evaluated the cost saving obtained if CDUS was employed as a first line surveillance tool following EVAR, as well as comparing the two entities in terms of efficacy.

PATIENTS & METHODS

Postoperative surveillance CTs and CDUS scans in the 145 patients who have undergone EVAR from 1st June 2003 to 1st July 2010 were compared for the detection of endoleak and determination of residual sac size.

RESULTS

Adopting a protocol where CDUS was employed as the first line surveillance tool following EVAR would result in a reduction in the number of postoperative CTs required in 2010 from 235 to 36. Based on 2010 costings, this would equate to an estimated reduction in expenditure from €117,500 to €34,915 a saving of €82,585. CDUS had a sensitivity of 100% and a specificity of 85% in the detection of endoleaks compared to CT. The positive predictive value was 28% and negative predictive value 100%. The Pearson Coefficient correlation of 0.96 indicates a large degree of correlation between CDUS and CT when measuring residual aneurysm size following EVAR.

CONCLUSION

CDUS can replace CT as the first line surveillance tool following EVAR. This is associated with a significant reduction in the cost of surveillance without any loss of imaging accuracy.

The value of the initial post-EVAR computed tomography angiography scan in predicting future secondary procedures using the Powerlink stent graft

OBJECTIVE

Current long-term surveillance after endovascular abdominal aortic aneurysm repair (EVAR) is based on high-resolution contrast-enhanced computed tomography (CT) scans at scheduled, lifelong intervals. The cancer and nephrotoxicity risks of interval CT scanning and prolonged radiation exposure are concerning. We sought to determine if surveillance CT angiography (CTA) can be safely reduced.

METHODS

From July 2000 to November 2007, 345 patients were enrolled in U.S. Food and Drug Administration trials of the Powerlink System (Endologix, Irvine, Calif). An independent core laboratory analyzed 1519 post-EVAR CT scans (N=1519) to 5 years to evaluate aneurysm size, migration, presence of endoleak, and evidence of graft obstruction. Analyses were conducted to determine the value of the initial CTA scan in predicting future secondary procedures in enrolled patients.

RESULTS

At any time during follow-up, CTA identified endoleak in 123 patients (36%), with 95% of endoleaks being type II. In addition, 49 patients underwent 72 secondary procedures at a mean of 22±21 months (range, 2-2007 days) after initial EVAR. These were based on clinical identification of limb ischemia in 13 interventions (18%) or core laboratory identification of abnormal CT finding in 58 interventions (81%). Of the 58 core laboratory identified findings, the inciting abnormality was present on the initial postoperative scan in 49 (84%). Of the remaining nine CT-driven procedures, three (5.2%) were due to late sac expansion attributed to type II endoleak (n=2) or endotension (n=1); two (3.4%) were for prophylactic reasons in the absence of endoleak; and four (6.8%) were in patients with type II endoleak not observed by the core laboratory and without sac expansion. The negative predictive value of the initial postoperative CTA for the need for a secondary procedure is therefore 96.4%, which can be improved to 97.6% with duplex ultrasound surveillance to detect sac expansion. Thus, a negative initial postoperative CTA is highly predictive of long-term freedom from secondary intervention.

CONCLUSIONS

Among enrolled patients with suitable anatomy for EVAR, most abnormalities that result in a secondary procedure are detected on the initial postoperative CTA or present with clinical symptoms. Long-term surveillance CTA may therefore be replaced by duplex ultrasound imaging if the initial postoperative CTA shows no abnormalities.

Duplex Ultrasound Scanning (DUS) Versus Computed Tomography Angiography (CTA) in the Follow-Up After EVAR

Introduction: Computed tomography angiography (CTA) is the gold standard follow-up modality after endovascular aneurysm repair (EVAR). A potential alternative noninvasive and less expensive modality is duplex ultrasound scanning (DUS). Methods: We studied 314 follow-up paired scans (DUS and CTA) in 59 patients with EVAR. Results: Endoleak—Endoleak was detected in 23.7% patients. The sensitivity and specificity rates of DUS were 54% and 95.3%, respectively. All 9 endoleaks that needed secondary intervention were detected on DUS. Eight of those were identified within a year after EVAR. Sac size—The mean difference in maximum diameter between the DUS and CTA was ≤5 mm in 84.5% of cases and ≤10 mm in 97.1%. Graft patency—There was 100% agreement between CTA and DUS. Conclusions: Duplex ultrasound scanning was reliable as it detected all the leaks that needed reintervention after EVAR. Duplex ultrasound scanning showed similar results to CTA in detecting sac size and patency.

Incidence and significance of nonaneurysmal-related computed tomography scan findings in patients undergoing endovascular aortic aneurysm repair

OBJECTIVE

This study examined the frequency and nature of incidental findings seen on computed tomography (CT) scans during preoperative and postoperative follow-up in patients undergoing endovascular aortic aneurysm repair (EVAR).

METHODS

Between January 1, 2000, and March 1, 2006, 176 consecutive patients who underwent EVAR at our institution were retrospectively reviewed. Patients were included in the study if all preoperative and postoperative surveillance CT scans were performed at our institution. Eighty-two patients, 26 women (32%) and 56 men (68%), met this criterion. Their mean age was 76 years (range, 51-103 years). Official CT scan reports were reviewed. Findings were considered primary incidental if they were noted on preoperative CT scans and secondary incidental if they appeared on surveillance CT scans but not on the preoperative study. Primary and secondary incidental findings were considered either benign (eg, gallstones, diverticulosis) or clinically significant if they warranted further workup (eg, suspicious masses or changes suggestive of malignancy, internal or diaphragmatic hernias, and diverticulitis). The median follow-up was 29 months (range, 3-60 months). Each incidental finding was counted only once, on the first scan in which it appeared.

RESULTS

Of the 82 patients, 73 (89%) had at least one primary incidental finding, and 14 (19%) of these were clinically significant. Secondary incidental findings, many of which were clinically significant, continued to appear throughout the follow-up period. The most common clinically significant primary incidental finding was the presence of a lung mass (n = 4). The most common clinically significant secondary incidental findings were lung mass (n = 6), liver mass (n = 6), and pancreas mass (n = 3). There was a significant difference in the proportion of men to women in the group with clinically significant incidental findings vs the group without clinically significant incidental findings (P = .03959). Differences between the groups with respect to age or aneurysm size were not significant.

CONCLUSION

CT scans yielded surprisingly large numbers of both primary and secondary incidental findings, many of which were clinically significant. Primary incidental findings were more common than secondary incidental findings; however, clinically significant findings were found at a consistent rate throughout the study period.

Surveillance of patients post-endovascular aneurysm repair

Endovascular aneurysm repair (EVAR) is increasingly being employed as an alternative to open surgical repair for patients with abdominal aortic aneurysms. The surveillance of patients post-EVAR has traditionally been carried out with regular computed tomographic scans which have in part been responsible for the high costs associated with this procedure. Duplex has been proposed as an alternative, but researchers have so far been unable to devise a standardised protocol for this surveillance. This review aims to provide a clear understanding of currently employed imaging modalities and discuss future surveillance possibilities for this patient group.