MR imaging for the detection of endoleaks in recipients of abdominal aortic stent-grafts with low magnetic susceptibility

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.

Detecting Aortic Graft Complications: A Spectrum of Computed Tomography Findings

Endovascular aneurysm repair (EVAR) is a successful technique as well as an excellent alternative to the surgical management of abdominal aortic aneurysms. EVAR has improved the mortality and morbidity of many patients who would have otherwise suffered greatly from the consequences of abdominal aortic aneurysms. However, EVAR is not without complications. Some complications require lifelong surveillance, whereas others may necessitate immediate surgical intervention. We discuss the various modalities available for the surveillance as well as the common complications that can be seen on computed tomography.

Dynamic volumetric CT angiography for the detection and classification of endoleaks: application of cine imaging using a 320-row CT scanner with 16-cm detectors

PURPOSE

To assess the feasibility and diagnostic performance of dynamic volumetric computed tomography (CT) angiography with large-area detectors in the detection and classification of endoleaks after endovascular aneurysm repair (EVAR).

MATERIALS AND METHODS

Low-dose dynamic volumetric CT angiography performed with the patient in Fowler position was used to scan the entire stent graft with a 16-cm-area detector during the first follow-up examination after EVAR. There were 39 consecutive patients (36 men and 3 women; mean age, 74 y ± 8.7) examined with approximately 14-20 intermittent scans (temporal resolution, 2 s; scan range, 160 mm). The effective radiation dose, image quality, interobserver and intraobserver agreement for endoleak detection, and time delay between peak enhancement of the aorta and endoleaks were evaluated.

RESULTS

All examinations with the patient in Fowler position enabled the entire stent graft to be scanned and were rated as diagnostic. The mean effective radiation dose was 13.1 mSv. Endoleaks were detected in eight patients (type Ia, n = 1; type II, n = 6; type III, n = 1). Interobserver agreement (κ = 0.794) and intraobserver agreement (κ = 1.00) for detection of endoleaks were excellent. The mean time delay between peak enhancement of the aorta and the endoleaks was significantly less for type I/III endoleaks (2.0 s ± 0) compared with type II endoleaks (5.3 s ± 1.0; P < .001).

CONCLUSIONS

Low-dose dynamic volumetric CT angiography performed with the patient in Fowler position is feasible after EVAR. Dynamic information, including cine imaging, the timing of peak enhancement, and the Hounsfield units index, is useful in detecting and classifying endoleaks.

Magnetic resonance imaging is more sensitive than computed tomography angiography for the detection of endoleaks after endovascular abdominal aortic aneurysm repair: a systematic review

OBJECTIVES

The purpose of this systematic review was to examine whether magnetic resonance imaging (MRI) or computed tomography angiography (CTA) is more sensitive for the detection of endoleaks in patients with abdominal aortic aneurysm (AAA) after EVAR.

DESIGN

Systematic review.

MATERIALS AND METHODS

A systematic electronic search was performed. Articles were included when post-EVAR patients were evaluated by both MRI as index test and CTA as comparison. Methodological quality was assessed with the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) tool. Primary outcome was the proportion of patients in whom MRI detected additional endoleaks, which were not seen with CTA.

RESULTS

Eleven articles were included. The overall methodological quality of the articles was good. In total, 369 patients with 562 MRI and 562 CTA examinations were included. A total of 146 endoleaks were detected by CTA; MRI detected all but two of these endoleaks. With MRI 132 additional endoleaks were found.

CONCLUSIONS

MRI is more sensitive compared to CTA for the detection of post-EVAR endoleaks, especially for the detection of type II endoleaks. MRI should be considered in patients with continued AAA growth and negative or uncertain findings at CTA.

Imaging Surveillance following Endovascular Aneurysm Repair

Endoleaks are unique complications of endovascular aneurysm repair (EVAR) that necessitate lifelong imaging surveillance for the patient. Several imaging modalities may be used to monitor the patient for endoleaks and other complications related to the stent graft. At present, computed tomographic angiography remains the gold standard for the detection of endoleaks. Other modalities that can be used to detect endoleaks include magnetic resonance, ultrasonography, nuclear medicine techniques, and pressure monitoring. In addition, follow-up imaging with digital subtraction angiography is important for endoleak classification and to guide decisions regarding therapy. In this article, we review the classification of endoleaks and discuss the different imaging strategies available for post-EVAR surveillance.

Prospective, intraindividual comparison of MRI versus MDCT for endoleak detection after endovascular repair of abdominal aortic aneurysms

This study compares MRI and MDCT for endoleak detection after endovascular repair of abdominal aortic aneurysms (EVAR). Forty-three patients with previous EVAR underwent both MRI (2D T1-FFE unenhanced and contrast-enhanced; 3D triphasic contrast-enhanced) and 16-slice MDCT (unenhanced and biphasic contrast-enhanced) within 1 week of each other for endoleak detection. MRI was performed by using a high-relaxivity contrast medium (gadobenate dimeglumine, MultiHance). Two blinded, independent observers evaluated MRI and MDCT separately. Consensus reading of MRI and MDCT studies was defined as reference standard. Sensitivity, specificity, and accuracy were calculated and Cohen's k statistics were used to estimate agreement between readers. Twenty endoleaks were detected in 18 patients at consensus reading (12 type II and 8 indeterminate endoleaks). Sensitivity, specificity, and accuracy for endoleak detection were 100%, 92%, and 96%, respectively, for reader 1 (95%, 81%, 87% for reader 2) for MRI and 55%, 100%, and 80% for reader 1 (60%, 100%, 82% for reader 2) for MDCT. Interobserver agreement was excellent for MDCT (k = 0.96) and good for MRI (k = 0.81). MRI with the use of a high-relaxivity contrast agent is significantly superior in the detection of endoleaks after EVAR compared with MDCT. MRI may therefore become the preferred technique for patient follow-up after EVAR.

Imaging Techniques for Detection and Management of Endoleaks after Endovascular Aortic Aneurysm Repair1

Endovascular aortic aneurysm repair (EVAR) is evolving into a viable alternative to open surgical repair for many patients with abdominal and thoracic aortic aneurysms. Endoleak development is a complication of EVAR and represents one of the limitations of this procedure. Endoleaks represent blood flow outside the stent-graft lumen but within the aneurysm sac. Lifelong imaging surveillance of patients after EVAR is critical to detect endoleaks for the patient's benefit and to determine the long-term performance of the stent-graft. Although computed tomographic angiography is the most commonly used examination for imaging surveillance, magnetic resonance angiography, ultrasonography, and digital subtraction angiography all have a role in endoleak detection and management. This review will focus on imaging techniques used for endoleak detection and the role imaging surveillance plays in the overall care of the post-EVAR patient.

Detection of Endoleaks after Endovascular Aneurysm Repair with Use of Technetium-99m Sulfur Colloid and 99m Tc-labeled Red Blood Cell Scans

PURPOSE

This study was performed to determine whether endoleaks could be detected after endovascular aneurysm repair (EVAR) with use of technetium-99m sulfur colloid and (99m)Tc-labeled red blood cell (RBC) nuclear medicine scans.

MATERIALS AND METHODS

There were 13 patients enrolled in this study: nine with endoleaks seen on computed tomographic (CT) angiography and four with no endoleak on CT angiography. All patients underwent regularly scheduled surveillance CT angiography examination after EVAR to evaluate for endoleak. Endoleak detection was then attempted in each patient with two nuclear medicine scans: a (99m)Tc sulfur colloid scan and a (99m)Tc-labeled RBC scan. Flow images (5 seconds per frame) were obtained for 1 minute after intravenous administration of 555 MBq (15 mCi) (99m)Tc sulfur colloid. Sequential dynamic images were then obtained every minute for 30 minutes. Next, a (99m)Tc-labeled RBC study was performed after the intravenous administration of 370-1,073 MBq (10-29 mCi) in vitro labeled (99m)Tc RBCs. Flow images were obtained, followed by sequential dynamic images obtained every minute for 30 minutes. Single photon emission CT images of the abdomen were then acquired. The nuclear medicine scans were evaluated for the presence or absence of endoleak independent of the CT angiography findings.

RESULTS

Of the nine patients with endoleaks on CT angiography, seven (78%) had them detected by nuclear medicine examinations. Two of the nine endoleaks seen on CT angiography (22%) were not seen on either scintigraphic examination. All patients with no endoleak on CT angiography had their nuclear medicine scans correctly interpreted as showing no endoleak present (n = 4; 100%). No complications occurred as a result of the nuclear medicine scans.

CONCLUSIONS

Endoleaks can be detected with (99m)Tc sulfur colloid and (99m)Tc-labeled RBC nuclear medicine scans. This initial work suggests that the sensitivities of these scintigraphic scanning methods for endoleak detection are lower than that of CT angiography.

Type II Endoleak after Endoaortic Graft Implantation: Diagnosis with Helical CT Arteriography

PURPOSE

To retrospectively assess endoleak shapes and locations within aneurysms to differentiate type II from type I and type III endoleaks.

MATERIALS AND METHODS

The institutional review board granted an exemption for this HIPAA-compliant study; patient informed consent was not required. A retrospective review of arterial phase helical computed tomographic (CT) studies and medical records was performed for 39 patients (29 men, 10 women; age range, 60-89 years; mean, 78.5 years) who had an endoleak after endoaortic graft implantation for treatment of abdominal aortic aneurysm and who subsequently underwent angiography (n = 25), surgery (n = 8), or long-term follow-up (n = 6) to classify their endoleak into a specific type. At CT, endoleak shape (tubular or nontubular) and location (central or peripheral) were recorded. An endoleak was classified as type II if it contained a peripheral tubular component (PTC) near the aortic wall, with or without an identifiable feeding vessel. Endoleaks without these features were classified as type I or III. The Fisher exact test was used to assess associations between CT findings and endoleak type.

RESULTS

There were 22 type II and 17 type I or III endoleaks. CT enabled correct identification of 22 (100%) of 22 type II endoleaks, all of which contained a PTC. Of 17 type I or III endoleaks, only two (12%) contained a PTC and were misclassified as type II endoleaks; the remaining 15 (88%) were correctly classified. Overall, CT enabled correct identification of endoleaks as type II or type I or III in 37 (95%) of 39 patients. PTCs were significantly more common (P < .001) in type II than in type I or III endoleaks, with a sensitivity, specificity, accuracy, negative predictive value, and positive predictive value of 100%, 88.2%, 94.9%, 100%, and 91.7%, respectively.

CONCLUSION

A PTC is a statistically significant predictor of type II endoleak in most patients.

Recurrent endoleak detection and measurement of aneurysm size with CTA after coil embolization of endoleaks

PURPOSE

The optimal modality for following aneurysm size and detecting endoleaks after endovascular aneurysm repair (EVAR) remains controversial. Computed tomographic angiography (CTA) has been widely employed but can be limited by metal artifact from stents, which is exacerbated by embolization coils placed during the treatment of type 2 endoleaks. The authors assessed interobserver agreement of CTA for measuring aneurysm size and presence of recurrent endoleak in patients with prior coil embolization of type 2 endoleaks.

MATERIALS AND METHODS

A total of 65 CTAs were retrospectively reviewed in a cohort of 27 patients (25 men; two women; mean age, 77.4 years) who had prior endoleak embolization after EVAR. Endoleak embolizations included transarterial (n=8) and translumbar (n=19) approaches. In each patient, maximal aneurysm diameter and presence/absence of recurrent endoleak was measured independently by two observers. Cohen's Kappa statistic was used to assess interobserver agreement, as well as paired two-tailed Student t tests for aneurysm diameter.

RESULTS

Recurrent type 2 endoleaks were detected with CTA in eight of 27 patients (30%) and on 13 of 65 CTAs (20%). A high degree of correlation (98.5%) was also seen between the two observers for presence of endoleak (Kappa=0.95). Mean aneurysm diameter for the entire cohort correlated closely between both observers: 54.8 mm+/-1.1 for observer A and 54.9 mm+/-1.1 for observer B (P=.66). There was a disagreement between the readers of greater than 2 mm regarding aneurysm size in 13.8% of the CTAs (nine of 65 CTAs).

CONCLUSION

Despite the presence of streak artifact on CTA following coil embolization of type 2 endoleaks, CTA remains a useful study for following patients. The presence of embolization coils does not prevent CTA measurement of aneurysm diameter and detection of recurrent endoleak with a high degree of interobserver agreement.

MRI versus helical CT for endoleak detection after endovascular aneurysm repair

OBJECTIVE

The objective of our study was to investigate the diagnostic accuracy of MRI and helical CT for endoleak detection.

SUBJECTS AND METHODS

Fifty-two patients underwent endovascular aneurysm repair with nitinol stent-grafts. Follow-up data sets included contrast-enhanced biphasic CT and MRI within 48 hr after the intervention; at 3, 6, and 12 months; and yearly thereafter. The endoleak size was categorized as < or = 3%, > 3% < or = 10%, > 10% < or = 30%, or > 30% of the maximum cross-sectional aneurysm area. A consensus interpretation of CT and MRI was defined as the standard of reference.

RESULTS

Of 252 data sets, 141 showed evidence for endoleaks. The incidence of types I, II, and III endoleaks and complex endoleaks was 3.2%, 40.1%, 8.7%, and 4.0%, respectively. The sensitivity for endoleak detection was 92.9%, 44.0%, 34.8%, and 38.3% for MRI, biphasic CT, uniphasic arterial CT, and uniphasic late CT, respectively. The corresponding negative predictive values were 91.7%, 58.4%, 54.7%, and 56.1%, respectively. The overall accuracy of endoleak detection and correct sizing was 95.2%, 58.3%, 55.6%, and 57.1% for MRI, biphasic CT, uniphasic arterial CT, and uniphasic late CT, respectively.

CONCLUSION

MRI is significantly superior to biphasic CT for endoleak detection and rating of endoleak size, followed by uniphasic late and uniphasic arterial CT scans. MRI shows a significant number of endoleaks in cases with negative CT findings and may help illuminate the phenomenon of endotension. Endoleak rates reported after endovascular aneurysm repair substantially depend on the imaging techniques used.

Use of CT Angiography to Classify Endoleaks after Endovascular Repair of Abdominal Aortic Aneurysms

PURPOSE

Accurate endoleak detection and classification is critical for the follow-up of patients who have undergone endovascular aneurysm repair (EVAR). This determination is often made with computed tomography angiography (CTA). This investigation was performed to determine the accuracy of CTA in the classification of endoleaks in patients who have undergone EVAR.

MATERIALS AND METHODS

Thirty-six patients with endoleaks underwent both CTA and conventional contrast digital subtraction angiography (DSA) to determine endoleak etiology. Two independent radiologists determined the source of the endoleak based on a retrospective review of the CTA. The results of the CTA-based endoleak classification were compared to the reference standard, contrast DSA.

RESULTS

There was agreement regarding endoleak classification between CTA and DSA on 86% of the patients (31 of 36 patients). Correlation between the CTA reading of the two readers was 94% (34 of 36 patients), yielding a kappa statistic of 0.8. In three patients, the CTA reading incorrectly classified endoleaks as type 2 when the endoleaks were actually type 1 endoleaks on DSA. One patient was incorrectly classified as having a type 1 endoleak on CTA when it was a type 2 endoleak on DSA. Finally, one patient had a type 1 endoleak on DSA that was incorrectly classified as a type 3 endoleak on CTA. The change in CTA endoleak classification based on the DSA resulted in a significant change in patient management in four of the 36 patients (11%).

CONCLUSIONS

Endoleak classification based on CTA correlates fairly well with DSA findings. However, optimal endoleak management requires performance of selective angiograms with DSA to classify endoleaks that are detected on CTA.

Type II Endoleaks after Endovascular Repair of Abdominal Aortic Aneurysms: Natural History

PURPOSE

To retrospectively determine the natural history of type II endoleaks detected at thin-section multi-detector row computed tomographic (CT) angiography.

MATERIALS AND METHODS

Neither institutional review board approval nor patient informed consent was required. Between December 1999 and December 2000, 83 patients (73 men and 10 women; mean age, 61 years; range, 55-75 years) underwent endovascular repair of an infrarenal abdominal aortic aneurysm with an endoluminal stent graft. Postprocedural abdominal CT angiography was performed every 3-12 months for the evaluation of endoleaks and the maximal sac diameter. A retrospective analysis of all postprocedural CT angiographic reports was performed until November 2003 to document the presence and development of type II endoleaks and the maximal orthogonal aneurysmal sac size. Findings at CT angiography were evaluated with regard to clinical outcomes and treatment in all patients in whom type II endoleaks were observed. The postprocedural follow-up period was 1.5-4.5 years (mean, 2.5 years).

RESULTS

Twenty type II endoleaks were identified in 16 (19%) of the 83 patients. Four (20%) of the 20 endoleaks were embolized secondary to an increasing aneurysmal sac size when compared with that at preoperative CT angiography. These four leaks occurred in two patients, each with two separate endoleaks. Sixteen (80%) of the 20 endoleaks in 14 patients were managed with continued observation. In these patients, the aneurysmal sac size was stable or had decreased when compared with the size at preoperative CT angiography. Ten (62.5%) of the 16 endoleaks have sealed spontaneously during the follow-up, and six (37.5%) have persisted with stable or decreased aneurysmal sac size. None of the patients experienced aneurysmal sac rupture.

CONCLUSION

Type II endoleaks with a stable or decreased aneurysmal sac size can be followed up with CT angiography secondary to the high rate of spontaneous resolution and a low risk of rupture.

Angioscanner hélicoïdal de l’aorte abdominale

The purpose was to illustrate that single or multirow spiral CT angiography has become the main modality for the examination of the abdominal aorta. Our multidisciplinary group investigates weekly 15 abdominal aortas, with a single slice spiral CT since 1995, and a 4 row detector spiral CT since 1999. CT scans protocols and parameters optimization for the 2 CT systems are described. Indications and results of CT to investigate the various abdominal aortic diseases are illustrated and discussed: aneurisms (pretherapeutic staging, selection of indications of endovascular stent-grafting); obstructive aorto-arteriopathies (pretherapeutic staging, follow up after endovascular revascularization); dissection (diagnosis, pretherapeutic staging, follow up); inflammatory diseases; normal patterns and principal complications after surgery. Situations where multislice CT is superior to single slice CT and compared advantages of MRI are discussed. CT is at the present time the main technique to image abdominal aorta. Multislice CT is especially interesting to explore the whole aorta, poly traumatisms, and to plan and follow up endovascular treatments.

Surveillance for endoleaks: How to detect all of them

Endovascular aneurysm repair has proven to be a valuable alternative to open repair in selected patients. This less invasive procedure, however, requires long-term surveillance for its own set of potential complications, including perigraft leakage, or endoleak. This article focuses on the detection of these leaks, first defining and classifying endoleaks and then describing various means of detecting them, including computed tomographic angiography, magnetic resonance angiography, color-flow duplex ultrasonography, and conventional angiography.

Magnetic resonance angiography

MRA and MRI have become increasingly important diagnostic modalities in vascular surgery. The ability to obtain cross-sectional and angiographic images by these noninvasive and non-nephrotoxic modalities represents one of the most significant advances in vascular surgery over the past decade. We review the current status of MRI and MRA in vascular surgical practice.

Endovascular treatment of abdominal aortic aneurysm

BACKGROUND

Endovascular repair of abdominal aortic aneurysm has become widely used. Supporters claim high success rates, few complications and a dramatically reduced hospital stay. However, endoleak, endotension and reports of endoprosthesis rupture are causes of concern.

METHODS

A Medline search was undertaken to identify articles on endovascular repair of abdominal aortic aneurysm. Additional papers were identified by manual scanning of the references from key articles.

RESULTS AND CONCLUSION

Endoleak is a potentially serious complication of the endovascular technique and occurs in a significant proportion of patients. It is still not possible to judge whether the presence of an endoleak alone signifies failure of treatment, and the long-term durability of prosthetic covered stents is unknown. However, endovascular repair does appear to confer a degree of protection from rupture although patients must be advised of the need for life-long imaging surveillance and, perhaps, further intervention.

Imaging modalities for the detection and management of endoleaks

Although endovascular aneurysm repair (EVAR) has shown promising initial results, there are unique complications to this procedure. Endoleaks, which do not occur after traditional surgical repair of abdominal aortic aneurysms, are detected in patients undergoing EVAR and are thought by some to be one of the limitations of this procedure. Endoleaks may continue to perfuse and pressurize the aneurysm sac, thereby conferring an ongoing risk of aneurysm enlargement and/or rupture. Because of this, accurate endoleak detection and classification is essential following EVAR. Surveillance of patients is critical to determine the long-term performance of the stent grafts. Although this is usually accomplished with contrast-enhanced spiral computed tomography scans performed at regular intervals, duplex ultrasonography exams; magnetic resonance angiography; and digital subtraction angiography all have a role in endoleak detection and classification. This article will cover imaging modalities used to detect endoleaks. In addition, we will cover which imaging exams should be performed to help with endoleak management.

Quand, comment et pourquoi réaliser une imagerie d’un anévrisme de l’aorte abdominale ?

Usually atherosclerotic in origin, aneurysms of the abdominal aorta (AAA) tend to involve the infrarenal aorta. Their biphasic exponential growth pattern, initially slow then accelerated, results in a risk of rupture. Surgical management is recommended for aneurysm diameters of 45-50mm or for growth rates more than 5mm in 6 Months. Imaging is useful for detection and follow-up of nonsurgical aneurysms, presurgical evaluation of aneurysms, and postsurgical follow-up. Frequently asymptomatic, AAA frequently is an incidental finding at the time of abdominal US. The size of the aneurysm sac, the presence of a neck and the size of the iliac arteries are assessed at the time of initial US detection. US is sufficient for follow-up of small aneurysms. Cross sectional imaging evaluation is necessary when surgery is contemplated. Readily available, multidetector row CT scanners with advanced image post-processing capabilities provide all the necessary information prior to surgical or endovascular management: evaluation of the aneurysm sac and neck, iliac and visceral arteries, and adjacent organs. Angiography with graduated catheters remains sometimes indicated. MR angiography provides results similar to CT but is less readily available and is usually reserved for patients with contraindication to iodinated contrast material. While follow-up imaging after surgical management is seldom performed, it is mandatory after endovascular management and includes KUB, Doppler US and CT or MR angiography.