Detection of endoleak with enhanced ultrasound imaging: comparison with biphasic computed tomography

Best Practice Guidelines: Imaging Surveillance After Endovascular Aneurysm Repair

OBJECTIVE. Abdominal aortic aneurysm is a significant cause of morbidity and mortality in the United States. Endovascular aneurysm repair (EVAR) is the preferred treatment modality. Surveillance imaging after EVAR detects potential complications. The most common complication is endoleak, which can predispose the aorta to rupture. This article provides a comprehensive and evidence-based review regarding surveillance imaging after EVAR to help readers understand current societal guidelines, guide institutional protocols, and provide a framework to facilitate safe, cost-effective, and clinically relevant imaging of patients after EVAR. CONCLUSION. Lifelong surveillance is necessary for patients who have undergone EVAR. Triple-phase CT angiography (CTA) within 30 days after EVAR is necessary to triage patients appropriately and guide future imaging. Patients without endoleak on initial CTA can be monitored with annual duplex ultrasound. Patients with type I or type III endoleaks should be referred for intervention. Patients with type II and type V endoleaks should be referred for intervention only if the sac diameter grows by more than 1 cm. MR angiography should be used primarily as a problem-solving modality or in patients with contraindications to contrast media or radiation. Strong consideration should be given to more frequent surveillance in patients who have undergone EVAR who have aneurysms with a hostile neck anatomy compared with those patients with favorable neck anatomy.

Contemporary imaging methods for the follow-up after endovascular abdominal aneurysm repair: a review

Abdominal aortic aneurysm (AAA) is defined as a localized enlargement of the aortic cross-section where the diameter is greater than 3 cm or more than 50% larger than the diameter in a normal segment. The most important complication of AAA is rupture, which, if untreated, results in mortality rates of up to 90%. Conventional open surgical repair is associated with significant 30-day mortality. Endovascular aneurysm repair (EVAR) is a significantly less invasive procedure; it is related to a lower early mortality rate and a lower number of perioperative complications. Although EVAR is a minimally invasive technique, lifelong follow-up imaging is necessary due to possible late complications including endoleak, recurrent aneurysm formation, graft infection, migration, kinking and thrombosis. The total rate of complications after EVAR is estimated at approximately 30%, and the rate of complications that require intervention is 2–3%. Early detection and progression analysis of such situations is crucial for proper intervention.

Is contrast-enhanced ultrasound (CEUS) superior to computed tomography angiography (CTA) in detection of endoleaks in post-EVAR patients? A systematic review and meta-analysis

OBJECTIVE

The purpose of this systematic review and meta-analysis was to assess the sensitivity and specificity of contrast-enhanced ultrasound (CEUS) compared to computed tomography angiography (CTA) for the detection of endoleaks within endovascular aortic aneurysm repair (EVAR) surveillance at time of follow up.

METHODS

A comprehensive literature search was undertaken among the four major databases (PubMed, Embase, Scopus and Ovid) to identify all articles assessing diagnostic specificity and accuracy with comparative modality (CEUS vs CTA) for endoleaks in adult patients at time of follow-up following EVAR. Databases where evaluated and assessed to October 2018.

RESULTS

A total of 1773 patients were analysed from across 18 included studies in the quantitative analysis of the parameters of interest. There was no significant difference in detection rate of endoleak type I with detection rate 4.3% for both groups OR 1.09, 95% CI [0.78, 1.53], p = 0.62; type II endoleak detection rate was 22% in the CEUS group vs 23% in the CTA group OR 1.16, 95% CI [0.75-1.79], p = 0.50; while type III detection rate was 1.8% in CEUS group vs 2% in CTA group OR 0.85, 95% CI [0.43, 1.68], p = 0.64. However, the sensitivity rate for endoleak detection was higher in CEUS (p = 0.001) while no difference in specificity rate was noted (p = 0.28). There was higher rate of missed endoleaks in CTA groups (n = 12 vs n = 20).

CONCLUSION

Evidences from this study suggest that contrast-enhanced ultrasound scan post-EVAR can be utilised as safe and effective method in screening for endoleaks during post-EVAR surveillance without exposing the patient for additional risk of radiation and contrast. CEUS conveys no inferiority to CTA in detecting endoleaks.

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.

A Systematic Review of Ultrasound or Magnetic Resonance Imaging Compared With Computed Tomography for Endoleak Detection and Aneurysm Diameter Measurement After Endovascular Aneurysm Repair

PURPOSE

To analyze the literature comparing ultrasound [duplex (DUS) or contrast-enhanced (CEUS)] or magnetic resonance imaging (MRI) with computed tomography angiography (CTA) for endoleak detection and aneurysm diameter measurement after endovascular aneurysm repair (EVAR).

METHODS

A systematic review identified 31 studies that included 3853 EVAR patients who had paired scans (DUS or CEUS vs CTA or MRI vs CTA) within a 1-month interval for identification of endoleaks during EVAR surveillance. The primary outcome was the number of patients with an endoleak detected by one test but undetected by another test. Results are presented for all endoleaks and for types I and III endoleaks only. Aneurysm diameter measurements between CTA and ultrasound were examined using meta-analysis.

RESULTS

Endoleaks were seen in 25.6% (985/3853) of patients after EVAR. Fifteen studies compared DUS with CTA for the detection of all endoleak types. CTA had a significantly higher proportion of additional endoleaks detected (214/2346 vs 77/2346 for DUS). Of 19 studies comparing CEUS with CTA for the detection of all endoleak types, CEUS was more sensitive (138/1694) vs CTA (51/1694). MRI detected 42 additional endoleaks that were undetected by CTA during the paired scans, whereas CTA detected 2 additional endoleaks that MRI did not show. CTA had a similar proportion of additional types I and III endoleaks undetected by CEUS or MRI. Of 9 studies comparing ultrasound vs CTA for post-EVAR aneurysm diameter measurement, the aneurysm diameter measured by CTA was greater than ultrasound (mean difference -1.70 mm, 95% confidence interval -2.45 to -0.96, p<0.001).

CONCLUSION

This study demonstrated that CEUS and MRI are more accurate than CTA for the detection of post-EVAR endoleaks, but they are no better than CTA for detecting types I and III endoleaks specifically. Aneurysm diameter differences between CTA and ultrasound should be considered when evaluating the change in aneurysm diameter postoperatively.

Contrast-enhanced ultrasound (CEUS) versus computed tomography angiography (CTA) in detection of endoleaks in post-EVAR patients. Are delayed type II endoleaks being missed? A systematic review and meta-analysis

PURPOSE

The purpose of this systematic review is to assess the accuracy of contrast-enhanced ultrasound (CEUS) to computed tomography angiography (CTA) for the detection of endoleaks within EVAR surveillance program.

MATERIAL AND METHODS

A systematic review in Pubmed, Embase and Cochrane database was performed. Articles assessing diagnostic accuracy and comparative modality (CTA vs. CEUS) for endoleaks in adult patients within surveillance programs were retrieved. Methodological assessment was performed, using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) tools. The sensitivity and specificity of data were extracted and statistical analysis was performed using MetaDiSc version 1.4.

RESULTS

Eight articles were found eligible (n = 454 patients). The pooled sensitivity of CEUS at detecting endoleak is 0.914 (CI 0.866-0.949) and pooled specificity is 0.782 (CI 0.741-0.820).

CONCLUSION

The CEUS with its dynamic nature and longer scanning window demonstrated to be a highly sensitive modality for endoleak detection in comparison to CTA in delayed endoleaks type II.

CT angiography in the diagnosis of cardiovascular disease: a transformation in cardiovascular CT practice

Computed tomography (CT) angiography represents the most important technical development in CT imaging and it has challenged invasive angiography in the diagnostic evaluation of cardiovascular abnormalities. Over the last decades, technological evolution in CT imaging has enabled CT angiography to become a first-line imaging modality in the diagnosis of cardiovascular disease. This review provides an overview of the diagnostic applications of CT angiography (CTA) in cardiovascular disease, with a focus on selected clinical challenges in some common cardiovascular abnormalities, which include abdominal aortic aneurysm (AAA), aortic dissection, pulmonary embolism (PE) and coronary artery disease. An evidence-based review is conducted to demonstrate how CT angiography has changed our approach in the diagnosis and management of cardiovascular disease. Radiation dose reduction strategies are also discussed to show how CT angiography can be performed in a low-dose protocol in the current clinical practice.

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.

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.

Endoleaks after endovascular abdominal aortic aneurysm repair: what one needs to know

PURPOSE OF REVIEW

To review the current state of diagnosis, treatment, and outcomes of the different types of endoleaks after endovascular abdominal aortic aneurysm repair (endovascular aneurysm repair, EVAR).

RECENT FINDINGS

Endoleaks are the most frequent complication after EVAR, the most common indication for secondary interventions, and the most common cause of rupture after EVAR. Imaging is critical for detecting endoleaks. Type I and III endoleaks require urgent intervention to prevent aneurysm rupture. Intervention for other endoleaks or endotension is indicated if the aneurysm sac continues to grow during follow-up. The majority of endoleaks can be treated with endovascular techniques. Open surgical conversion may be considered if the risk of aneurysm rupture is high and if no endovascular options are available or if they have failed.

SUMMARY

Endoleaks continue to be a challenge and this article discusses the different treatment options for endoleaks after EVAR. Long-term follow-up after EVAR is required to diagnose and treat endoleaks before they result in aneurysm rupture. The majority of endoleaks can be treated with endovascular techniques, although open surgical interventions may be required in selected patients.

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.

Abdominal aortic aneurysm: Treatment options, image visualizations and follow-up procedures

Abdominal aortic aneurysm is a common vascular disease that affects elderly population. Open surgical repair is regarded as the gold standard technique for treatment of abdominal aortic aneurysm, however, endovascular aneurysm repair has rapidly expanded since its first introduction in 1990s. As a less invasive technique, endovascular aneurysm repair has been confirmed to be an effective alternative to open surgical repair, especially in patients with co-morbid conditions. Computed tomography (CT) angiography is currently the preferred imaging modality for both preoperative planning and post-operative follow-up. 2D CT images are complemented by a number of 3D reconstructions which enhance the diagnostic applications of CT angiography in both planning and follow-up of endovascular repair. CT has the disadvantage of high cummulative radiation dose, of particular concern in younger patients, since patients require regular imaging follow-ups after endovascular repair, thus, exposing patients to repeated radiation exposure for life. There is a trend to change from CT to ultrasound surveillance of endovascular aneurysm repair. Medical image visualizations demonstrate excellent morphological assessment of aneurysm and stent-grafts, but fail to provide hemodynamic changes caused by the complex stent-graft device that is implanted into the aorta. This article reviews the treatment options of abdominal aortic aneurysm, various image visualization tools, and follow-up procedures with use of different modalities including both imaging and computational fluid dynamics methods. Future directions to improve treatment outcomes in the follow-up of endovascular aneurysm repair are outlined.

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.

[Imaging of endoleaks after endovascular aneurysm repair (EVAR) with contrast-enhanced ultrasound (CEUS)]

Endoleaks following endovascular aneurysm repair (EVAR) are common and present a diagnostic challenge in the follow-up after EVAR. Contrast-enhanced ultrasound (CEUS) is a promising new method for the diagnosis and follow-up of endoleaks. CEUS with SonoVue allows a rapid and non-invasive diagnosis in the follow-up after EVAR. The sensitivity and specificity of conventional ultrasound compared to the multislice CT angiography is estimated to be 33-63% and 63-93%, respectively. These values can be increased through the use of CEUS in up to 98-100% (sensitivity) and 82-93% (specificity). This article describes the etiology, classification and importance of different types of endoleaks. The value of CEUS in this clinical scenario will be discussed.

Endovascular stent graft repair of abdominal aortic aneurysms: Current status and future directions

Endovascular stent graft repair of abdominal aortic aneurysm (AAA) has undergone rapid developments since it was introduced in the early 1990s. Two main types of aortic stent grafts have been developed and are currently being used in clinical practice to deal with patients with complicated or unsuitable aneurysm necks, namely, suprarenal and fenestrated stent grafts. Helical computed tomography angiography has been widely recognized as the method of choice for both pre-operative planning and post-operative follow-up of endovascular repair (EVAR). In addition to 2D axial images, a number of 2D and 3D reconstructions are generated to provide additional information about imaging of the stent grafts in relation to the aortic aneurysm diameter and extent, encroachment of stent wires to the renal artery ostium and position of the fenestrated vessel stents. The purpose of this article is to provide an overview of applications of EVAR of AAA and diagnostic applications of 2D and 3D image visualizations in the assessment of treatment outcomes of EVAR. Interference of stent wires with renal blood flow from the hemodynamic point of view will also be discussed, and future directions explored.

Type II endoleaks: when is intervention indicated and what is the index of suspicion for types I or III?

One of the principal reasons for failure of endovascular aneurysm repair (EVAR) is the occurrence of endoleaks, which regardless of size or type can transmit systemic pressure to the aneurysm sac. There is little debate that type I endoleaks (poor proximal or distal sealing) are associated with continued risk of aneurysm rupture and require treatment. Similarly, with type III endoleak, there is agreement that the defect in the device needs to be addressed; however, what to do with type II endoleaks and their effect on long-term outcome are not so clear. Aneurysm sac change is a primary parameter for determining the presence of an endoleak and assessing its impact. While diameter measurement has been the most commonly used method for determining sac changes, volume measurement has now been proven superior for monitoring structural changes in the 3-dimensional sac. Determining the source of an endoleak and the direction of flow are necessary for proper classification; however, while computed tomographic angiography has high sensitivity and specificity for detecting endoleaks, it is limited in its ability to show the direction of flow. Contrast-enhanced duplex ultrasound, on the other hand, is better able to quantify flow and characterize endoleaks. Flow is evidence of pressure, and increasing intrasac pressure increases wall tension, thus inducing progressive aneurysm expansion until rupture. Hence, determining intrasac pressure is becoming a vital component of endoleak assessment. All endoleaks can create systemic pressure inside the aneurysm sac, and there are a variety of intrasac pressure transducers being evaluated to assess this effect. A clinical pathway for patients with suspected type II endoleaks is based on a combination of imaging and pressure measurements. Imaging alone requires at least two interval examinations to determine the trend, while pressure measurements give immediate reassurance or an indication to intervene. Although still under development, pressure measurement is destined for general use and will provide a scientific basis for the management of type II endoleaks.

Endoleak detection and classification after endovascular treatment of abdominal aortic aneurysm: value of CEUS over CTA

This paper focuses on the diagnostic value of CEUS in the detection and characterization of endoleaks in comparison with other imaging modalities, primary CDUS and CTA in the follow-up of endovascular abdominal aortic aneurysm repair. CEUS is an interesting alternative technique because of its limited costs and lack of exposure to ionizing radiation. However, CTA cannot currently be substituted because it enables a more precise evaluation of aneurysm morphologic changes, aneurysm sac diameter, graft anchorage and integrity. CEUS could be used along with CTA when the latter reveals the presence of endoleak, to provide a better characterization of it taking advantage of the angiodynamic behavior of the contrast agent that permits an easier visualization of the agent flow into the sac. It could also be indicated when aneurysm diameter increases and CTA did not show sac reperfusion or to monitor type II endoleaks reducing the use of CTA with consequent reduction of costs and exposure to radiation.

The Durability of Evar — What are the Evidence and Implications on Follow-Up?

Background and Aims:

To investigate the durability of EVAR and to explore the evidence for follow-up investigations. Furthermore, to study the patients' impressions of follow-up investigations, and how complications and secondary procedures influence cost-effectiveness.

Material and Methods:

263 patients were treated by EVAR from february 1995-february 2007. The series is divided into two groups with the year 2000 as a cut-off point since a new generation of stent grafts was then introduced. Early and late complications and secondary procedures were recorded. A questionnaire study was performed to investigate the patients' views on the follow-up program.

Results:

There was a significant reduction of complications from period I to period II, which was also reflected in the reduction of secondary procedures. Freedom from secondary procedures were 47% and 93% at 5 years follow-up in the two periods, respectively. In phase II, 7.5% of the patients needed a secondary procedure. Limb extension and femoro-femoral bypass were the most common procedures. Since late complications still occur, and can be unpredictable, a follow-up program is necessary. The vast majority of the patients tolerated the follow-up program well.

Conclusions:

Although the number of complications following EVAR has decreased significantly over the years, a thorough follow-up program is still necessary. This follow-up regime is well tolerated by the patients. Reduction of secondary procedures is important to improve the cost-effectiveness of EVAR.

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.

Assessing the effectiveness of endografts: Clinical and experimental perspectives

The increasing use of endografts to treat abdominal aortic aneurysms has prompted the need for improved postoperative imaging and surveillance. Although patients benefit from decreased morbidity with endovascular repair compared with open abdominal aortic aneurysm repair, the long-term outcome of stent repair has yet to be fully determined. The persistence of endoleaks highlights the need for close follow-up, particularly because this may lead to aneurysm rupture, even after endograft repair. The current mainstay of assessing the healing of endografts is obtaining serial helical computed tomography angiography (CTA) to identify endoleaks, graft migration, thrombosis, and structural failure. CTA is not completely effective at identifying endoleaks and predicting aneurysm rupture, however. Other modalities have been studied to improve on current imaging methods, including three-dimensional CTA with volumetric analysis, contrast-enhanced duplex ultrasound imaging, cine magnetic resonance angiography, and explant analysis. In vitro and large-animal models of abdominal aortic aneurysm have also been developed to study the pathophysiology and treatment response of aneurysm exclusion. Thus, clinical and experimental models of endograft healing are attempting to define the optimal method of postoperative surveillance of endovascular repair.

Contrast ultrasound imaging: the best method to detect type II endoleak during endovascular aneurysm repair follow-up☆

OBJECTIVES

Type II endoleak is the most common complication after endovascular aneurysm repair and require close surveillance. Hence, the need to validate new techniques as alternative to helical CT-scan, the reference standard. The aim of this study is to evaluate the efficacy of Cadence Contrast Pulse Sequencing ultrasound technique with second generation contrast agents in detecting endoleaks, and to compare the results with data obtained from CTA.

METHODS

30 patients with endovascular stent grafts, during their regular follow-up consisting in serial CT and ultrasound exams performed at discharge, at one and six months and at one year thereafter, previous informed consent, were enrolled in a prospectic double blind study design in order to compare triphasic helical CT-scan to another adjunctive ultrasound investigation (Cadence CPS technique with Sono Vue). No more than 15 days occurred between the two examinations. In the study were evaluated only data obtained from the comparison of the two concomitant investigations, independently from the follow-up. Variables analysed were changes in the maximum diameter of the aneurysmal sac, presence and type of endoleak, if detected. In the case of disagreement between the two diagnostic tools angiography was performed.

RESULTS

One patient dropped out because of violation of the study protocol (a stroke occurred in the time interval between the two investigations). Both exams visualised patency and proper graft placement in all the remaining patients. Aneurysmal diameters with both investigations overlapped (r(s):0.98). In 21 patients no endoleak was detected with a significant aneurysmal sac shrinkage (P<0.001). In seven patients both methods confirmed presence of endoleak. Ultrasonography detected all type of endoleaks, while CT-scan was uncertain in one. Moreover, in one patient CT-angiography showed an increased aneurysmal diameter without other evidence, while a contrast ultrasound investigation disclosed a type II low-flow endoleak, confirmed by angiography.

CONCLUSIONS

The Cadence Contrast Pulse Sequencing with echo contrast agent is an ultrasound technique that substantially improves the ultrasound diagnostic reliability.

Imaging of aortic abnormalities with contrast-enhanced ultrasound. A pictorial comparison with CT

Aortic abnormalities are commonly encountered and may represent a diagnostic challenge in patients with acute or chronic clinical symptoms. Contrast-enhanced ultrasound (CEUS) with low mechanical index (low MI) is a new promising method in the diagnosis and follow-up of pathological aortic lesions. CEUS with SonoVue allows a more rapid and noninvasive diagnosis, especially in critical patients because of its bedside availability. This review compares CEUS findings with those documented on computed tomography angiography (CTA), allowing the reader to appreciate the usefulness of CEUS in this clinical situation.

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

OBJECTIVE

To investigate the value of duplex ultrasound scanning (DUSS) in the routine follow up of patients following EVAR.

METHODS

Imaging was reviewed for 310 consecutive patients undergoing EVAR at a single centre. Concurrent ultrasound and CT scans were defined as having occurred within 6 months of each other. There were 244 paired concurrent DUSS and CT scans which were used for further analysis. These modalities were compared with respect to sensitivity, specificity, positive and negative predictive values and level of agreement (by Kappa statistics) using CT as the 'gold standard'.

RESULTS

DUSS failed to detect a number of endoleaks which were seen on CT and the sensitivity of this test was therefore poor (67%). However, the specificity of DUSS compared more favourably with a value of 91%. Positive predictive values ranged from 33-100% but negative predictive values were more reliable with values of 91-100% at all time points post operatively. There were no type I leaks, or endoleaks requiring intervention which were missed on DUSS. Overall, there was a 'fair' level of agreement between the two imaging modalities using Kappa statistics.

CONCLUSION

Although DUSS is not as sensitive as CT scanning in the detection of endoleak, no leaks requiring intervention were missed on DUSS in this study. DUSS is much cheaper than CT and avoids high doses of radiation. DUSS therefore remains a valuable method of follow up after EVAR and can reduce the need for repeated CT scans.

Comparison of Contrast-Enhanced Ultrasound and Computed Tomography in Classifying Endoleaks After Endovascular Treatment of Abdominal Aorta Aneurysms: Preliminary Experience

The purpose of the study was to assess the effectiveness of contrast-enhanced ultrasonography (CEUS) in endoleak classification after endovascular treatment of an abdominal aortic aneurysm compared to computed tomography angiography (CTA). From May 2001 to April 2003, 10 patients with endoleaks already detected by CTA underwent CEUS with Sonovue to confirm the CTA classification or to reclassify the endoleak. In three conflicting cases, the patients were also studied with conventional angiography. CEUS confirmed the CTA classification in seven cases (type II endoleaks). Two CTA type III endoleaks were classified as type II using CEUS and one CTA type II endoleak was classified as type I by CEUS. Regarding the cases with discordant classification, conventional angiography confirmed the ultrasound classification. Additionally, CEUS documented the origin of type II endoleaks in all cases. After CEUS reclassification of endoleaks, a significant change in patient management occurred in three cases. CEUS allows a better attribution of the origin of the endoleak, as it shows the flow in real time. CEUS is more specific than CTA in endoleak classification and gives more accurate information in therapeutic planning.

Endoleakage after endovascular treatment of abdominal aortic aneurysms: diagnosis, significance and treatment

Endoleak, also called leakage, leak and Perigraft leak, is a major complication and its persistence represents a failure of endovascular aortic aneurysm repair. Its detection and treatment is therefore of primary importance, since endoleak can be associated with pressurization (increase in pressure) of the sac, resulting in expansion and rupture of the aneurysm. The aim of this paper is to discuss the definition, significance, diagnosis and different options to treat endoleak.

Contrast-enhanced Duplex surveillance after endovascular abdominal aortic aneurysm repair: Improved efficacy using a continuous infusion technique

INTRODUCTION

Currently, postoperative endoleak surveillance after endovascular aortic aneurysm repair (EVAR) is primarily done by computed tomography (CT). The purpose of this study was to determine the efficacy of contrast-enhanced ultrasonography scans to detect endoleaks by using a novel infusion method and compare these findings with those of CT angiography (CTA).

METHODS

Twenty male patients (mean age, 70.4 years) underwent surveillance utilizing both CTA and contrast-enhanced color Duplex imaging. One 3-mL vial of Optison (Perfluten Protein A microspheres for injection) and 57 mL normal saline, for a total of 60 mL, were administered to each patient as a continuous infusion at 4 mL/min via a peripheral vein. Each study was optimized with harmonic imaging, and a reduced mechanical index of 0.4 to 0.5, compression of 1 to 3, and a focal zone below the aorta to minimize microsphere rupture. One minute was allowed from the time of infusion to the appearance of contrast in the endograft. Flow was evaluated within the lumen of the graft and its components, as was the presence or absence of endoleaks. Findings were compared with standard color-flow Duplex imaging and CT utilizing CTA reconstruction protocols.

RESULTS

All patients evaluated had modular endografts implanted for elective aneurysm repair. Contrast-enhanced duplex scans identified nine endoleaks: one type I and eight type II. No additional endoleaks were seen on CTA. However, CTA failed to recognize three type II endoleaks seen by contrast-enhanced ultrasound. The continuous infusion method allowed for longer and more detailed imaging. An average of 46.8 mL of the contrast infusion solution was used per patient.

CONCLUSIONS

Contrast enhanced Duplex ultrasonography accurately demonstrates endoleaks after EVAR and may be considered as a primary surveillance modality. Continuous infusion permits longer imaging time.

Long-term follow-up of surgically excluded popliteal artery aneurysms with multi-slice CT angiography and Doppler ultrasound

The purpose of this study was to evaluate the role of multi-slice computed tomography (MSCT) angiography in the follow-up of popliteal artery aneurysms (PAAs) that have been operated on. Aneurysm exclusion and progression, graft patency and graft-related complications were analyzed. Fourteen patients with 21 surgically excluded PAAs were evaluated with MSCT angiography with slice thickness of 1.25 mm. The mean follow-up time was 67 months. MSCT demonstrated blood flow in six non-excluded PAAs (24%), with an average increase in the diameter of 21 mm over time. Fifteen PAAs demonstrated no blood flow and revealed an average decrease of 7 mm in diameter. The origin of this residual perfusion was demonstrated, and collaterals were involved in five of six non-excluded PAAs. In addition, MSCT demonstrated three graft stenoses. Furthermore, two occluded grafts were visualized. Twenty-four percent of the patients after surgical exclusion of PAAs revealed residual perfusion within the aneurysmal sac during follow-up, with a significant increase in the aneurysmal size with MSCT. Moreover, evaluation of the graft patency could also be done as could demonstration of anastomotic abnormalities. Thus, MSCT might be considered as a new tool to evaluate residual collateral feeding of popliteal aneurysmal sac and could be useful in identification and localization of feeding vessels.

Computed Tomography Versus Color Duplex Ultrasound for Surveillance of Abdominal Aortic Stent-Grafts

PURPOSE

To compare the ability of computed tomography (CT) and color duplex ultrasound (CDUS) to detect endoleak and accurately measure aortic aneurysm diameters after endovascular repair.

METHODS

Between February 2000 and October 2004, 178 consecutive patients (156 men; mean age 74 years, range 49-89) were treated with aortic stent-grafts (86 Ancure, 55 AneuRx, and 37 Excluder). The follow-up protocol included serial CT and CDUS at 1 month and every 6 months thereafter. Sensitivity, specificity, positive predictive value, negative predictive value, and Kappa statistics (kappa) were calculated using CT as the gold standard; Bland-Altman analysis was used to determine the 95% limits of agreement. Paired and unpaired t tests and correlation coefficients were used to compare the methods.

RESULTS

Follow-up ranged from 1 to 53 months (mean 16), during which 367 paired CT and CDUS studies were acquired. The mean diameter of the AAA sac after repair was 5.15 cm by CT versus 4.99 cm by CDUS (p=0.07); 93% of paired studies were somewhat similar (<or=5 mm). Mean pre to postoperative AAA size changes throughout follow-up were -0.60 mm for CT versus -0.58 mm for CDUS (p=0.78). Thirty-four (19%) endoleaks were detected (26 early and 8 late). Versus CT, the sensitivity, specificity, positive predictive value, and negative predictive value of CDUS for detecting endoleaks were 68%, 99%, 85%, and 97%, respectively (kappa=0.73). CDUS was more accurate in detecting type I endoleak than type II (88% versus 50%, p=0.046).

CONCLUSIONS

Although CDUS has good correlation to CT in measuring the size of AAAs, it has a lower sensitivity in detecting endoleak, particularly type II. Therefore, CT scans should remain the primary imaging modality for the diagnosis of endoleak.

Color Duplex Ultrasonography Is Insensitive for the Detection of Endoleak After Aortic Endografting: A Systematic Review

PURPOSE

To synthesize the available evidence regarding the diagnostic accuracy of color duplex ultrasonography (CDU) versus the accepted gold-standard of contrast-enhanced computed tomography (CT) for the detection and classification of endoleaks after aortic endografting.

METHODS

A systematic search of the literature was conducted using electronic bibliographical databases and other means to gather articles published between 1991 and 2004. Articles were scrutinized against inclusion/exclusion criteria that broadly followed the QUADAS quality assessment guidelines. The results of diagnostic CDU were expressed for each study as a 2x2 contingency table, and summary statistics (sensitivity/specificity with 95% confidence intervals [CI]) were calculated. Pooled and random effects meta-analyses were performed.

RESULTS

Eight published studies and 2 unpublished studies from Charing Cross and St. George's Hospitals (711 patients, 1355 paired scans performed > or = 1 month after endografting) were eligible for inclusion. From meta-analyses, the pooled sensitivity of CDU (versus CT as the gold standard) was 69% (95% CI 52% to 87%) and the specificity of CDU was 91% (95% CI 87% to 95%). These parameters did not appear to vary over time when a smaller dataset of 117 patients with 239 paired scans was used to compare CT and CDU specifically at 3, 12, and 24 months after endografting. Endoleak classification data, which was derived from only 5 small studies, indicated that CDU appeared to have better diagnostic accuracy in detecting type I or type III endoleaks compared with type II endoleaks; however, the data were insufficient for statistical analysis.

CONCLUSIONS

CDU currently does not have sufficient diagnostic accuracy for the detection of all endoleaks in routine clinical practice. The diagnostic accuracy of CDU may improve if type II endoleaks are ignored.

Type II lumbar endoleaks: Hemodynamic differentiation by contrast-enhanced ultrasound scanning and influence on aneurysm enlargement after endovascular aneurysm repair

OBJECTIVE

The objective of this study was to differentiate type II lumbar endoleaks on the basis of dynamic features identified by contrast-enhanced ultrasound scanning (CUS) and to evaluate the role of this differentiation in detecting abdominal aortic aneurysm (AAA) enlargement > or =1 mL/mo.

METHODS

Eighteen male patients (mean age, 71.8 years) with type II lumbar endoleak suspected at CUS underwent computed tomography angiography (CTA) and digital subtraction angiography (DSA). On CTA, AAA volumes and endoleak visualization and volume were assessed. At CUS, performed after a bolus of 1.5 to 2.4 mL of a second generation blood pool contrast agent, the following parameters were evaluated: presence of contrast material within the aneurysmal sac (endoleak), delay of endoleak detection (wash-in) and disappearance (washout) from the beginning of contrast injection, visualization of inflow and outflow vessels, and presence of cavity filling. Statistical analysis was performed regarding endoleak features at CUS, endoleak detection at CTA, and rate of AAA enlargement.

RESULTS

DSA confirmed all the endoleaks. Mean +/- standard deviation wash-in and washout times were 121.9 +/- 132.6 and 337.2 +/- 193.7 seconds, respectively; a significant relation was observed between these two parameters (P < .01, analysis of variance). By Youden plots, endoleaks were classified as hyperdynamic when wash-in was <100 seconds (n = 10, 55.5%) and/or washout was <520 seconds (n = 13, 72.2%). A slower washout was associated with nonvisualized outflow (66.7%) and/or inflow arteries (66.7%) ( P < .05). Eight endoleaks (44.4%) were missed at CTA; it occurred in hypodynamic endoleaks, absence of detectable inflow or outflow vessels, and absence of cavity filling at CUS (P < .05). Overall mean AAA volume increase rate was 1.1 +/- 1.7 mL/mo. By multiple logistic regression model, the washout time > or = 520 seconds was the only independent predictor of AAA volume increase > or = 1 mL/mo (8 patients, 44.4%).

CONCLUSION

Type II lumbar endoleaks show different hemodynamic features at CUS, which might influence the rate of aneurysm enlargement, addressing the need for treatment.

Migration versus apparent migration: importance of errors due to positioning variation in plain radiographic follow-up of aortic stent-grafts

PURPOSE

To demonstrate the influence of radiographic positioning on the assessment of stent-graft migration using plain radiographs following endovascular abdominal aortic aneurysm repair.

METHODS

Equations were derived to correct for artifactual stent-graft migration introduced by geometric distortion due to variations in positioning between radiographs acquired at different times. A phantom system was used to validate the equations.

RESULTS

Errors in stent position increase with (1) the distance of the aortic stent-graft from the midline and (2) differences in radiographic centering points in the craniocaudal direction; other variables have little effect. For typical stent positions, errors are small if the centering changes by <8 cm. Consistent radiographic positioning to within 4 cm on successive imaging studies limits errors to 1.5 mm. Even if artifactual migration is large, the true migration can be reliably calculated to within 2 mm.

CONCLUSIONS

Artifactual migration due to variation in radiographic centering is not usually clinically significant if care is taken to center radiographs consistently. Radiographs in which artifactual migration may be important are readily identified, and mathematical correction is straightforward.

Color-flow duplex ultrasound scan versus computed tomographic scan in the surveillance of endovascular aneurysm repair

OBJECTIVE

The purpose of this study is to compare both computed tomographic scan (CT) and color flow duplex ultrasound scanning (CDU) as surveillance modalities for clinically significant endoleaks and to evaluate concordance in abdominal aortic aneurysm (AAA) diameter measurements in patients after endovascular aneurysm repair (EVAR) in a busy hospital vascular laboratory.

METHODS

We conducted a retrospective review of all patients who underwent endovascular repair of abdominal aortic aneurysms between February 1996 and November 2002 and had same-day CT and CDU studies. Ninety-seven patients enrolled in phase II clinical studies of Ancure devices had long-term follow-up with both modalities. The other patients underwent simultaneous studies, usually only at the 1-month postoperative visit. Peripheral vascular studies were performed by two certified vascular technicians; all CT scans were reviewed by one vascular surgeon. CT was used as the standard against which the sensitivity, specificity, negative predictive value, and positive predictive value of CDU in endoleak detection was determined. Statistics were performed by using the paired t test; a P value <.05 was considered significant. Kappa statistic was used to assess the correlation between CDU and CT in identifying endoleaks. The correlation between CT and CDU in AAA size measurements as well as in serial size measurements was also determined.

RESULTS

Four hundred ninety-five same-day CT and CDU examinations were reviewed in 281 patients. Patients had an average follow-up of 34.6 months (range, 1 to 72 months). Thirty-five leaks were identified among the patients studied (12.4% overall). In comparison with CT, diagnosis of endoleak with ultrasound scanning was associated with a sensitivity of 42.9%, specificity of 96.0%, positive predictive value of 53.9%, and negative predictive value of 93.9%. The correlation between the two modalities was modest (kappa statistic 0.427). The minor axis transverse diameter as measured by ultrasound and CT scans (4.81 +/- 1.1 cm on CT and 4.55 +/- 1.1 cm on ultrasound) correlated closely (r =.93, P <.001.) Seventy percent of paired studies differed by < or =5 mm. Changes in aneurysm size throughout follow-up were -.29 +/-.71 cm on CT scan -.34 +/-.57 cm on duplex ultrasound scan. The correlation coefficient was.65 (P <.001). There was no significant difference in the change as measured by either modality on the paired t test.

CONCLUSIONS

Although CDU demonstrates a high degree of correlation with CT scan in determining aneurysm size change over time, it has a low sensitivity and positive predictive value in endoleak detection. In the hospital vascular laboratory at a large tertiary care center, CDU cannot effectively replace CT scan in surveillance after EVAR.

Contrast-enhanced ultrasound imaging for aortic stent-graft surveillance

PURPOSE

To compare unenhanced and enhanced ultrasound imaging to computed tomographic angiography (CTA) or magnetic resonance angiography (MRA) for surveillance of aortic endografts.

METHODS

Thirty consecutive patients (29 men; mean age 69 years, range 50-82) who underwent endovascular aortic aneurysm repair agreed to participate in a follow-up program. Patients underwent CTA (26/30) or MRA (4/30), plain abdominal radiography, and unenhanced and enhanced ultrasound examinations at 3, 12, and 24 months to evaluate aneurysm diameter, endoleaks, and graft patency. The accuracy of ultrasound was compared with CTA or MRA as the reference standards.

RESULTS

Twenty-six patients reached the 24-month assessment (mean follow-up 30 months, range 6-60). All endoleaks detected by CTA or MRA were confirmed by enhanced ultrasound; the aneurysm diameter in these patients remained unchanged or increased. In patients without endoleaks on any imaging method, the sac diameter remained unchanged or decreased. Endoleaks disclosed by enhanced ultrasound alone, all type II, numbered 16 at 3 months, 6 at 12 months, and 3 at 24 months. In this group, the aneurysm diameter remained unchanged or increased. Enhanced ultrasound yielded 100% sensitivity in detecting endoleaks, but compared with CTA and MRA, all endoleaks detected by enhanced ultrasound alone were false positives (mean specificity 65%). Nevertheless, because changes in the postoperative aneurysm diameter were similar in patients with endoleaks detectable on CTA/MRA and on enhanced ultrasound ("true positives") and in those with endoleaks detectable only on enhanced ultrasound ("false positives"), some endoleaks were possibly "true positive" results.

CONCLUSIONS

Enhanced ultrasound is a useful method in the long-term surveillance of endovascular aortic aneurysm repairs, possibly in association with CTA or MRA. Enhanced ultrasound also seems able to identify endoleaks missed by other imaging techniques, but this conclusion awaits further investigation.

Controversies in the management of type II "branch" endoleaks following endovascular abdominal aortic aneurysm repair

Successful endovascular aortic aneurysm repair (EVAR) is often defined as complete exclusion of blood flow within the aneurysm sac. Perigraft flow, also known as endoleak, is the most common complication following EVAR. Attachment site related endoleaks (type I) are generally considered to warrant some form of intervention due to the belief that they represent a risk for future rupture. Management of type II endoleaks, also known as branch or collateral endoleaks, is more controversial. Some advocate a policy of watchful-waiting whereas others treat all type II endoleaks as soon as they are discovered. The following review explores the controversies pertaining to the management, diagnosis and surveillance imaging, and treatment of type II endoleaks.