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

Use of the Endoleak-to-Aortic Density Ratio to Distinguish Direct Endoleaks from Indirect Endoleaks after Endovascular Aortic Aneurysm Repair

PURPOSE

To define criteria to distinguish direct (type 1 or 3) from indirect endoleaks (type 2) in the arterial phase of contrast-enhanced computed tomography (CT) scans in patients with abdominal aortic aneurysms treated with endovascular aortic repair.

MATERIALS AND METHODS

This retrospective study was conducted from January 2009 to October 2020 and included consecutive patients treated endovascularly for a direct endoleak or an indirect endoleak associated with an enlarging aneurysm. The following characteristics were evaluated using contrast-enhanced CT: location, size, contact with the endograft, density, morphologic criteria, collateral artery enhancement, and endoleak-to-aortic density ratio. Statistical analysis included the Mann-Whitney U test, Pearson χ2 test, Fisher exact test, receiver operating characteristic curve analysis, and multivariable logistic regression.

RESULTS

Contrast-enhanced CT scans from 71 patients (87% men), who presented with 87 endoleaks (44 indirect and 43 direct endoleaks), treated by endovascular techniques were analyzed. Using visual criteria, 56% of the endoleaks were not characterizable as direct or indirect. An endoleak-to-aortic density ratio of >0.77 could properly distinguish direct from indirect endoleaks, with a theoretical accuracy of 98% (area under the receiver operating characteristic curve, 0.99), sensitivity of 95%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 96%.

CONCLUSION

An endoleak-to-aortic density ratio of >0.77 in the arterial phase of contrast-enhanced CT could be a strong discriminant of a direct-type endoleak.

Angiossarcoma mimetizando endoleak tardio pós-reparo endovascular de aneurisma de aorta infrarrenal: relato de caso

Resumo Em todo paciente submetido a reparo endovascular do aneurisma de aorta abdominal (REVA) que se apresente subitamente com quadro de dor abdominal ou sinais de choque, a hipótese de endoleak ou vazamento, com expansão do aneurisma e ruptura deve ser aventada. Apresentamos o caso de um paciente em pós-operatório de REVA que apresentou uma neoplasia de duodeno mimetizando um endoleak.

Imaging Findings of Atypical Type II Endoleak Through Vasa Vasorum After Abdominal Endovascular Aneurysm Repair

A type II endoleak (T2EL) is the most common endoleak after endovascular aneurysm repair (EVAR), and a persistent T2EL has been occasionally associated with aneurysmal enlargement. Typical findings of a T2EL consist of an endoleak cavity with inflow and outflow arteries of aortic branch vessels. However, an atypical T2EL, in which hypertrophied vasa vasorum and enlargement of a thrombosed aneurysm are observed, has no endoleak cavity. We have seen three cases of continuous aortic aneurysmal growth after EVAR caused by atypical T2ELs without endoleak cavities through developed vasa vasorum. In this report, the imaging findings of selective angiography and dynamic computed tomography of these cases are reviewed.

MDCT of endoleaks following endovascular repair of abdominal aortic aneurysms

Endovascular aneurysm repair has been used to repair abdominal aortic aneurysms but necessitates surveillance to diagnose the delayed possibility of endoleak formation. Multi-detector computer tomography (MDCT) of the abdomen is one imaging technique used to diagnose enlargement of the aneurysm sac that may be indicative of endoleaks. MDCT has a role in identifying the initial endoleak formation and providing signs suggestive of the specific endoleak subtype; thus it is necessary for radiologists to be familiar with the findings of endoleak seen on MDCT. In this pictorial review, we explore the various types of endoleaks and their appearance on MDCT.

Embolization by micro navigation for treatment of persistent type 2 Endoleaks after endovascular abdominal aortic aneurysm repair

Background:Endovascular repair has become established as a safe and effective method for treatment of abdominal aortic aneurysms. One major complication of this treatment is leakage, or endoleaks, of which type 2 leaks are the most common.Objective:To conduct a brief review of the literature and evaluate the safety and effectiveness of embolization by micronavigation for treatment of type 2 endoleaks.Method:A review of medical records from patients who underwent endovascular repair of abdominal aortic aneurysms identified 5 patients with persistent type 2 endoleaks. These patients were submitted to embolization by micronavigation.Results:In all cases, angiographic success was achieved and control CT scans showed absence of type 2 leaks and aneurysm sacs that had reduced in size after the procedure.Conclusion:Treatment of type 2 endoleaks using embolization by micronavigation is an effective and safe method and should be considered as a treatment option for this complication after endovascular repair of abdominal aortic aneurysms.

MDCT distinguishing features of focal aortic projections (FAP) in acute clinical settings

Focal aortic projections (FAP) are protrusion images of the contrast medium (focal contour irregularity, breaks in the intimal contour, outward lumen bulging or localized blood-filled outpouching) projecting beyond the aortic lumen in the aortic wall and are commonly seen on multidetector computed tomography (MDCT) scans of the chest and abdomen. FAP include several common and uncommon etiologies, which can be demonstrated both in the native aorta, mainly in acute aortic syndromes, and in the post-surgical aorta or after endovascular therapy. They are also found in some types of post-traumatic injuries and in impending rupture of the aneurysms. The expanding, routine use of millimetric or submillimetric collimation of current state-of-the-art MDCT scanners (16 rows and higher) all the time allows the identification and characterization of these small ulcer-like lesions or irregularities in the entire aorta, as either an incidental or expected finding, and provides detailed three-dimensional pictures of these pathologic findings. In this pictorial review, we illustrate the possible significance of FAP and the discriminating MDCT features that help to distinguish among different types of aortic protrusions and their possible evolution. Awareness of some related and distinctive radiologic features in FAP may improve our understanding of aortic diseases, provide further insight into the pathophysiology and natural history, and guide the appropriate management of these lesions.

Non-contrast MR imaging for detecting endoleak after abdominal endovascular aortic repair

Our aim was to investigate the possibility of ruling out endoleak after endovascular aortic repair (EVAR) of abdominal aortic aneurysm (AAA) using non-contrast MRI. Twenty-three patients (20 males, aged 73 ± 8 years) with an EVAR-treated AAA underwent 1.5-T MRI using axial, coronal and sagittal oblique true-FISP sequences. Two blinded and independent readers with 4 (R1) and 2 (R2) years of experience evaluated these images considering an area of even less than 5 mm in diameter with a signal intensity higher than that of normal muscles visible in the excluded aneurysmal sac as a sign of potential endoleak. The final assessment, mainly based on MR angiography and previous examinations, served as reference standard. Out of 23 patients, 13 (57%) were negative for endoleak at final assessment, while the remaining 10 (43%) were positive, with the following type distribution: Ia (n = 4), Ib (n = 2), II (n = 3), and III (n = 1). Sensitivity was 10/10 (100%; CI 95% 69-100%), specificity 7/13 (54%; 25-81%), accuracy 17/23 (74%; 52-90%), PPV 10/16 (63%; 35-85%) and NPV 7/7 (100%; 59-100%) for R1; 9/10 (90%; 56-100%), 8/13 (62%; 32-86%), 17/23 (74%; 52-90%), 9/14 (64%; 35-8%), and 8/9 (89%; 52-100%) for R2, respectively. Inter-reader Cohen κ was 0.810. A negative non-contrast true-FISP MR study can be used to rule out endoleak after EVAR of AAA. This hypothesis may contribute to the reduction of ionizing radiation exposure and contrast material administration for monitoring patients with an EVAR-treated AAA.

A multidetector tomography protocol for follow-up of endovascular aortic aneurysm repair

OBJECTIVE

The purpose of this study was to improve the use of 64-channel multidetector computed tomography using lower doses of ionizing radiation during follow-up procedures in a series of patients with endovascular aortic aneurysm repair.

METHODS

Thirty patients receiving 5 to 29 months of follow-up after endovascular aortic aneurysm repair were analyzed using a 64-channel multidetector computed tomography device by an exam that included pre-and postcontrast with both arterial and venous phases. Leak presence and type were classified based on the exam phase.

RESULTS

Endoleaks were identified in 8/30 of cases; the endoleaks in 3/8 of these cases were not visible in the arterial phases of the exams.

CONCLUSION

The authors conclude that multidetector computed tomography with pre-contrast and venous phases should be a part of the ongoing follow-up of patients undergoing endovascular aortic aneurysm repair. The arterial phase can be excluded when the aneurism is stable or regresses. These findings permit a lower radiation dose without jeopardizing the correct diagnosis of an endoleak.

Endovascular abdominal aortic aneurysm repair by interventional cardiologists--a community-based experience

INTRODUCTION

Endovascular repair of abdominal aortic aneurysm (AAA) is a relatively recent technology. In comparison to the conventional open surgical treatment for AAA, endovascular AAA repair (EVAR) combines a less-invasive approach with lower morbidity and mortality. There have been few studies regarding the performance of this procedure in a community-based setting. We report our experience of EVAR performed primarily by interventional cardiologists in a community hospital.

METHODS

In our community hospital setting, between September 2005 and November 2007, we included all patients who underwent EVAR by interventional cardiologists, with available on-site vascular surgical support. Clinical and serial computed angiographic imaging outcomes were followed by a retrospective chart review. Data collection tools included demographic and clinical characteristics, anatomical aneurysm features, length of stay, peri- and postprocedural complications, and mortality.

RESULTS

A total of 71 consecutive patients had EVAR attempted. The endovascular stent placement was successful in 67 (93%) patients. Thirty-day mortality in this study was 1 of 71 (1.4%). All four procedural failures and the single periprocedural mortality occurred in women. Mean follow-up was 12 months. There were a total of six mortalities and among these four were women (P ≤ 0.001); however, multivariate analysis revealed loss of significant difference in mortality (P = 0.16). Major complications following EVAR were noted in 10 of 71 (14%) patients.

CONCLUSION

EVAR can be successfully performed by experienced interventional cardiologists with vascular surgical support in a community-based setting. In our experience, there is acceptable rate of complications and mortality in a carefully selected patient population.

Endovascular aortic stent for thoracic and abdominal aortic aneurysm: imaging consequences and complications

Background: Endovascular stent-graft implantation has been used as an alternative to conventional open surgery in treatment of aortic aneurysm. Computed tomographic angiography (CTA) has been requested for follow-up and evaluation of aortic stent complications. Objective: Find the incidence of endovascular aortic stent complications and analyze the CTA features of postendovascular aortic stent consequences. Methods: Two radiologists reviewed CTA images of 635 patients who attended King Chulalongkorn Memorial Hospital between Sep 1, 2003 and Aug 31, 2008. Thirty-eight patients had endovascular aortic stent installation with 95 CTA images. The incidence of endovascular aortic stent complications, the image appearances including consequences and time-interval of endoleak were analyzed. Results: There were 23 thoracic aortic stents, 10 abdominal aortic stents and five combined stents for thoracic and abdominal aortic aneurysms. Twenty-eight cases had aortic stent complications (73.7%). Two cases had immediately post procedural complication of groin hematomas (7.1%). Ten patients had more than one finding. Findings of the stent-graft complications were as follows: 19 endoleaks, 15 stent thrombosis, five stents without covered-dissection, two stent kinkings, two iatrogenic focal aortic dissection, two air within aneurysm after stent installation and one spreading infected aortitis. The most common complication was endoleaks (53.6%), which could progress, be persistent or resolvable. Time-interval to detect endoleak was between 1 and 464 days. Conclusion: CTA can be used as modality of choice in demonstration of stent location, consequences, and complications. The stent complication was still high in the first five-year experience.

Endovascular abdominal aortic aneurysm repair: nonenhanced volumetric CT for follow-up

PURPOSE

To evaluate the clinical usefulness of volumetric analysis at nonenhanced computed tomography (CT) as the sole method with which to follow up endovascular abdominal aortic aneurysm repair (EVAR) and to identify endoleaks causing more than 2% volumetric increase from the previous volume determination.

MATERIALS AND METHODS

The study had institutional review board approval. Images were reviewed retrospectively in a HIPAA-compliant manner for 230 CT studies in 70 patients (11 women, 59 men; mean age, 74 years) who underwent EVAR. The scannning protocol consisted of three steps: (a) contrast material-enhanced CT angiography before endovascular stent placement, (b) contrast-enhanced CT angiography 0-3 months after repair to depict immediate complications, and (c) nonenhanced CT at 3, 6, and 12 months after repair. At each follow-up visit, immediate aortic volume analysis was performed. If the interval volumetric change was 2% or less, no further imaging was performed. If the volume increased by more than 2% on the nonenhanced CT image, contrast-enhanced CT angiography was performed immediately to identify the suspected endoleak. Confidence intervals (CIs) were obtained by using bootstrapping to account for repeated measurements in the same patients.

RESULTS

Mean volume decrease was -3.2% (95% CI: -4.7%, -1.9%) in intervals without occurrence of a clinically relevant endoleak (n = 183). Types I and III high-pressure endoleaks (n = 10) showed a 10.0% (95% CI: 5.0%, 18.2%) interval volumetric increase. Type II low-pressure endoleaks (n = 37) showed a 5.4% (95% CI: 4.6%, 6.2%) interval volumetric increase. Endoleaks associated with minimal aortic volume increase of less than 2% did not require any intervention. This protocol reduced radiation exposure by approximately 57%-82% in an average-sized patient.

CONCLUSION

Serial volumetric analysis of aortic aneurysm with nonenhanced CT serves as an adequate screening test for endoleak, causing volumetric increase of more than 2% from the volume seen at the previous examination.

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.