Endoleaks after Endovascular Repair of Abdominal Aortic Aneurysms

CIRSE Standards of Practice on Management of Endoleaks Following Endovascular Aneurysm Repair

BACKGROUND

Endoleaks represent the most common complication after EVAR. Some types are associated with ongoing risk of aneurysm rupture and necessitate long-term surveillance and secondary interventions.

PURPOSE

This document, as with all CIRSE Standards of Practice documents, will recommend a reasonable approach to best practices of managing endoleaks. This will include imaging diagnosis, surveillance, indications for intervention, endovascular treatments and their outcomes. Our purpose is to provide recommendations based on up-to-date evidence, updating the guidelines previously published on this topic in 2013.

METHODS

The writing group was established by the CIRSE Standards of Practice Committee and consisted of clinicians with internationally recognised expertise in endoleak management. The writing group reviewed the existing literature performing a pragmatic evidence search using PubMed to select publications in English and relating to human subjects up to 2023. The final recommendations were formulated through consensus.

RESULTS

Endoleaks may compromise durability of the aortic repair, and long-term imaging surveillance is necessary for early detection and correct classification to guide potential re-intervention. The majority of endoleaks that require treatment can be managed using endovascular techniques. This Standards of Practice document provides up-to-date recommendations for the safe management of endoleaks.

Type IIIb endoleak due to stent suture line fabric breakage in the Endurant stent graft: a case report

Background

Early type IIIb endoleak is a very rare complication of endovascular aneurysm repair (EVAR).

Case presentation

An 87-year-old man was diagnosed with infrarenal abdominal aortic aneurysm. The patient underwent EVAR using the Endurant stent graft. Postoperative color duplex ultrasound revealed a regular row of pulsatile blood flow from the main body and left leg. The blood flow appeared to be bleeding from the stent suture lines because of its regularity. Type IIIb endoleak was suspected due to stent suture line fabric breakage but was not treated surgically or endovascularly because of the patient’s poor general health status. Six months later, contrast-enhanced CT demonstrated a deformation and enlargement of the aneurysm sac as well as an oozing of the contrast medium on the main body and left limb. Thereafter, he died of a subdural hematoma due to a fall. Autopsy showed no visible abnormal erosion or holes on the graft fabric, suggesting that suture line fabric breakage may have existed during the manufacturing process.

Conclusions

Although rare, type IIIb endoleaks can occur even in the perioperative period after EVAR. Early type IIIb endoleaks may not resolve spontaneously and should be treated promptly, if possible.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40792-022-01415-8.

A systematic review of the current status of interventions for type II endoleak after EVAR for abdominal aortic aneurysms

OBJECTIVE

To study the mid- and long-term outcomes of type II endoleak treatment after EVAR and the technical aspects of different techniques to exclude endoleaks which different embolic agents.

METHODS

A systematic review was performed using the approach recommended by the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines for meta-analyses of interventional studies. The comprehensive search was conducted using the following database: MEDLINE, EMBASE, and the Cochrane Library. Patient characteristic, intervention approaches, embolic agents, and results at mid and long term follow up were studied.

RESULTS

A total of 6 studies corresponding to a total of 141 patients fulfilled the inclusion criteria with a mean age of 73-78.6 years and a mean duration of follow up varying from 25 to 42 months. There were different techniques for embolization used (translumbar, transarterial, and transcaval approach) with various types of embolic agents. In all studies, the indication for embolization of the type II endoleaks was sac enlargement of more than 5 mm. A wide range of technical success rate was reported regardless of the intervention strategy being used (17,6%-100%). The overall technical success rate of all studies was 62%.

CONCLUSION

This systematic review shows that there is a wide variety of techniques to exclude a persistent type II endoleak. Different kinds of embolic agents have be used. Due to a lack of peer reviewed data on longterm follow-up, it was not possible to come to recommendations what treatment would be the best for a durable exclusion of a persistent type II endoleak after an initially successful EVAR. There remains an urgent need for proper executed studies, either randomized or with close observation in relation to longer follow-up.

Artifacts in Contrast-Enhanced Ultrasound during Follow-up after Endovascular Aortic Repair: Impact on Endoleak Detection in Comparison with Computed Tomography Angiography

The study described here systematically analyzed how specific artifacts in contrast-enhanced ultrasound (CEUS) can affect the detection of endoleaks during follow-up after endovascular aortic repair (EVAR). Patients undergoing EVAR of atherosclerotic or mycotic abdominal aortic aneurysms using various standard and branched stent-graft material for visceral and iliac preservation were enrolled over 5 y and followed up with computed tomography angiography (CTA) and CEUS simultaneously. CEUS artifacts were frequently identified after EVAR procedures (59% of examinations) and were caused mainly by contrast agent, different prosthesis or embolization material and postinterventional changes in the aneurysm sac. This article describes how to identify important artifacts and how to avoid false-negative or false-positive interpretations of endoleaks. Despite artifacts, CEUS had higher sensitivity for endoleak detection after EVAR than CTA. CEUS was superior to CTA in the identification of late endoleaks type II and in follow-up examinations after embolization procedures, where beam-hardening artifacts limited CTA.

Feasibility and Safety of Sac Embolization Using N-Butyl Cyanoacrylate in Emergency Endovascular Aneurysm Repair for Ruptured Abdominal Aortic Aneurysms or Isolated Iliac Artery Aneurysms

PURPOSE

To evaluate the feasibility and safety of sac embolization with N-butyl cyanoacrylate (NBCA) in emergency endovascular aneurysm repair (EVAR) for ruptured abdominal aortic aneurysm (AAA) and iliac artery aneurysm (IAA) in comparison to EVAR without sac embolization.

MATERIALS AND METHODS

Between February 2012 and December 2019, among 44 consecutive patients with ruptured AAA or IAA, 29 underwent EVAR. Of these, 22 patients (median age 77.5 years; 18 men) had concomitant sac embolization using NBCA; the remaining 7 patients (median age 88 years; 6 men) underwent EVAR without sac embolization and form the control group. The technical success, clinical success (hemodynamic stabilization), procedure-related complications, and mortality were compared between the groups.

RESULTS

All EVAR procedures and embolizations were successful. The clinical success rates in the NBCA and control groups were 95% (21/22) and 71% (5/7), respectively (p=0.14). There was no complication related to the procedure. Type II endoleak occurred in 4 of 21 patients (19%) in the NBCA group vs none of the control patients. One patient (5%) died in the NBCA group vs 3 (43%) in the controls (p=0.034).

CONCLUSION

Sac embolization using NBCA in emergency EVAR appears to be feasible and safe for ruptured AAA and IAA.

Multicentre randomised controlled trial to evaluate the efficacy of pre-emptive inferior mesenteric artery embolisation during endovascular aortic aneurysm repair on aneurysm sac change: protocol of Clarify IMA study

INTRODUCTION

Type II endoleak (EL) is frequently seen after endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA) and is often considered responsible for aneurysm sac enlargement if it persists. In order to reduce type II EL and consequent sac enlargement, pre-emptive embolisation of the inferior mesenteric artery (IMA), which is a main source for persistent type II EL, has been introduced in many vascular centres. At present, there is a lack of robust evidence to support the efficacy of pre-emptive embolisation of IMA on reduction of persistent type II EL with subsequent sac shrinkage.

METHOD AND ANALYSIS

This multicentre, randomised controlled trial will recruit 200 patients who have fusiform AAA ≥50 mm/rapidly enlarging fusiform AAA, with patent IMA, and randomly allocate them either to a pre-emptive IMA embolisation group or non-embolisation control group in a ratio of 1:1. The primary endpoint is the difference of aneurysm sac volume change assessed by CT scans between the pre-emptive IMA embolisation group and the control group at 12 months after EVAR. The secondary endpoints are defined as change of aneurysm sac volume in both groups at 6 and 24 months, freedom from sac enlargement at 12 and 24 months after EVAR, prevalence of type II EL at 1, 6, 12 and 24 months evaluated by contrast-enhanced CT, reintervention rate, aneurysm related mortality, overall survival, perioperative morbidity, volume of contrast media used during EVAR and dosage of radiation.

ETHICS AND DISSEMINATION

The protocol has been reviewed and approved by the ethics committee of Nara Medical University (No. 2113). The findings of this study will be communicated to healthcare professionals, participants and the public through peer-reviewed publications, scientific conferences and the University Hospital Medical Information Network Clinical Trials Registry home page.

TRIAL REGISTRATION NUMBER

UMIN000035502.

2D-shear wave elastography in the prediction of type II endoleaks after endovascular aneurysm repair

PURPOSE

To evaluate the usefulness of 2D-shear wave elastography (2D-SWE) in the prediction of type II endoleaks after endovascular aneurysm repair (EVAR) of abdominal aortic aneurysms (AAA).

MATERIAL AND METHODS

Twenty-nine patients underwent EVAR for AAA, and 2D-SWE was performed after EVAR. Follow-up contrast-enhanced CT and ultrasonography were performed to evaluate endoleaks in all patients. The median follow-up period was 12 months (range, 3-12 months). Patients were divided into two groups: one with an endoleak (endoleak group) and another without it (control group). We compared the elasticity index (EI) of intraluminal thrombus (ITL) and fresh thrombus (FT) between the two groups.

RESULTS

Type II endoleaks were confirmed in five of the 29 patients (endoleak group), and there were no endoleaks in the other 24 (control group). ILT was observed in 21 patients of the control group and in all patients of the endoleak group. There was a difference only in EI of ILT; the mean EI (± standard deviation) of ILT was 89 ± 16 kPA in the control group and 113 ± 25 kPA in the endoleak group (p=.037).

CONCLUSIONS

High EI of ILT may predict the occurrence of type II endoleaks after EVAR of AAA.

Case Report of Late Type IIIb Endoleak with Willis Covered Stent (WCS) and Literature Review

OBJECTIVE

We report a case of late type IIIb endoleak with Willis covered stent (WCS) developed 14 months after endovascular paraclinoid aneurysm repair.

METHODS

A 52-year-old woman presented with episodic headache, caused by a giant paraclinoid aneurysm. She underwent a successful 3.5 x 16mm WCS positioning to treat the aneurysm. Fourteen months later, the patient was admitted with the same symptoms. Digital subtraction angiography examination showed recurrence of the aneurysm, which was similar to the preoperative one. DynaCT (Siemens, Erlangen, Germany) indicated the intact of the metal structure of the stent without migration. Type IIIb endoleak (defect in the graft fabric) was confirmed with a whole aneurysm neck located in the middle part of the stent. The type IIIb endoleak was treated with another WCS (4.0 x 16mm). The immediate digital subtraction angiography imaging indicated that the endoleak disappeared and the aneurysm was completely occluded. Re-examination done 1 year after the second treatment showed a complete exclusion of the aneurysm sac.

CONCLUSIONS

Type IIIb endoleaks can be safely treated by the endovascular positioning of another WCS. Continuous surveillance after endovascular paraclinoid aneurysm repair for intracranial aneurysms is warranted to make ensure the safety of WCS.

Onyx Embolization for Occlusion of the Proximal Internal Iliac Artery During EVAR in Patients with Unsuitable Landing Zones in the Common Iliac Artery

BACKGROUND

Twenty percent of the patients with AAA have an aneurysm involving the common iliac arteries. Large common iliac diameter can be treated with an iliac branched device or extension of the stent graft to the external iliac artery with occlusion of the ipsilateral internal iliac artery (IIA) to prevent type 2 endoleaks. This study describes and evaluates a embolization technique using Onyx in conjunction with EVAR in aneurysms with poor landing zones in the common iliac arteries.

METHODS

Patients with Onyx IIA embolization during EVAR, identified from the hospital operating code database, constitute the study population. Onyx embolization was performed by injection at the IIA origin. Peri- and postoperative complications were collected from the medical records. Thin-sliced CT scan was performed 1 month and 1 year after the procedure.

RESULTS

Thirty-six patients with complex iliac anatomy and insufficient landing zones (without sealing possibility for standard stent grafts) were identified out of 243 consecutive EVAR treatments during a 13-year period. In seventeen patients (7%), the IIA was embolized with Onyx. Technical success was obtained in all 17 patients, without adverse event or procedural complication. No complication related to the embolization procedure was noted during follow-up.

CONCLUSIONS

During EVAR treatment of patients with aneurysm involving the common iliac artery, Onyx embolization of IIA is a feasible option without need of selective catheterization of the IIA orifice, potentially preserving important branches of the IIA and simplifying emergency procedures.

Numerical Modeling of Blood Flow in a Healthy Aorta and Aorta with Stent

The treatment of aortic aneurysm varies according to each patient. Stent implantation is one of many methods used to stabilize diseases. The information obtained from hemodynamic parameters in the pathological aorta with stent could help doctors in choosing the treatment before the surgery. In this context, the numerical simulation of fluid dynamics is an essential tool that can give us more detailed information that could be exploited by surgeons to find appropriate solutions to some pathologies. In this work, a study of two models of aortas: with and without stent was presented. A comparison of the results of changes in pressures and shear stresses of aortas in systolic and diastolic phases was discussed. The obtained results show a nearly similar tendency of variation for both models, which justifies the effectiveness of the type of stent chosen and its effect on the improvement of the blood flow. The methodology used in this work has revealed the detailed and necessary information for both cases studied and has shown the interest of the numerical tools for diagnosis and surgery.

Endovascular Repair for a Ruptured AAA due to a Combined Type IIIb and Ia Endoleak

We report a case of a ruptured abdominal aortic aneurysm (AAA) caused by a combined type IIIb and Ia endoleak. Also, we propose the mechanism that resulted in this combined endoleak. Specifically, a 71-year old-man, with a previous history of endovascular aneurysm repair (EVAR) for an AAA, was diagnosed with a contained rupture. CT scan depicted a type Ia endoleak and a migrated Talent endograft. A proximal aortic cuff sealed the endoleak, but intraoperative angiography revealed that a type IIIb endoleak coexisted due to fabric tear close to the Talent bifurcation. A second aortic cuff could not seal the fabric tear; so, in-lay parallel limbs were sequentially deployed as a “kissing endograft” technique inside the cuff. Simultaneous treatment of combined type IIIb and Ia endoleaks has not yet been described. Maybe the type IIIb endoleak is the primary entity causing sac enlargement, neck recontouring, proximal migration, and ultimately type Ia endoleak, which leads to huge enlargement and rupture. Placement of an aortic cuff to seal the proximal endoleak/migration and kissing endografts limbs for the fabric tear seems a safe option in such patients.

Contrast-enhanced ultrasound (CEUS) of the abdominal vasculature

Vascular diseases account for a significant proportion of abdominal pathology and represent a common referral source for abdominal ultrasonographic examinations. B-mode, color Doppler, and spectral Doppler analyses are well-established in the evaluation of abdominal blood vessels although they may occasionally be limited by lower sensitivity for slow flow visualization or the deeper location of abdominal vascular structures. The introduction of microbubbles as ultrasonographic contrast agents has rendered contrast-enhanced ultrasound (CEUS), a valuable complementary ultrasonographic technique, which is capable of addressing clinically significant problems and guiding patient management. The purpose of this pictorial review is to analyze the use of CEUS in the evaluation of abdominal vascular pathology and illustrate such applications by presenting representative images. Pathology discussed includes abdominal aortic aneurysm, post-endovascular treatment aorta, portal vein thrombosis, abdominal vascular trauma, and organ transplantation along with its complications.

Evolving clinical applications of contrast-enhanced ultrasound (CEUS) in the abdominal aorta

Ultrasound (US) represents the initial modality in the workup of abdominal aortic pathology based on the plethora of advantages including widespread availability, low cost, safety profile and repeatability. However, US has inherent limitations including limited spatial information of pathologic processes to neighboring structures, lower sensitivity to slow blood flow and aortic luminal irregularities. For evaluation of aortic pathology angiography has long been considered the gold standard. Non-invasive cross-sectional imaging techniques like computed tomography angiography (CTA) and magnetic resonance angiography (MRA) have gradually replaced interventional angiography for the evaluation of aorta, currently being regarded as the diagnostic imaging modalities of choice for diagnosis of virtually every aortic disease. Interventional angiography is currently primarily performed for treatment purposes of aortic pathology. The introduction of microbubbles as ultrasonographic contrast agents has rendered contrast-enhanced ultrasound (CEUS) an evolving valuable complementary technique with markedly increased diagnostic accuracy for certain aortic applications. CEUS is characterized by the potential to be performed in patients with impaired renal function. Due to its superior spatial and temporal resolution, ability for prolonged scanning and dynamic and real-time imaging, it provides clinically significant additional information compared to the standard Duplex US. The purpose of this paper is to discuss the currently available literature regarding abdominal aortic applications of CEUS, briefly elaborate on CEUS technique and safety and present cases in order to illustrate the added value in aortic pathologies. Conditions discussed include abdominal aortic aneurysm (AAA), aneurysm rupture, aneurysm surveillance after endovascular repair, dissection and aortitis.

Prospective Comparison of Reduced-Iodine-Dose Virtual Monochromatic Imaging Dataset From Dual-Energy CT Angiography With Standard-Iodine-Dose Single-Energy CT Angiography for Abdominal Aortic Aneurysm

OBJECTIVE

The purpose of this study was to compare the image quality of reduced-iodine-dose single-source dual-energy CT angiography (CTA) with that of standard-iodine-dose single-energy CTA in examinations of patients with abdominal aortic aneurysm and to assess the effect of the concentration of iodinated contrast medium on intravascular enhancement and image quality of reduced-iodine-dose CTA.

SUBJECTS AND METHODS

In a prospective randomized clinical trial, 66 consecutively registered patients with abdominal aortic aneurysm who had previously undergone single-energy CTA (30-37 g I) underwent follow-up CTA at a reduced dose (21-27 g I) of iodinated contrast medium of either 270 mg I/mL (n = 33) or 320 mg I/mL (n = 33). Two readers independently evaluated virtual monochromatic imaging datasets (40-140 keV) and single-energy CTA images for image quality and noise and their preference for optimal energy virtual monochromatic imaging dataset. A value of p < 0.05 was considered statistically significant.

RESULTS

All 66 dual-energy CTA examinations were rated diagnostic with mean image quality and image noise scores of 4.8 and 4.5 for reader 1 and 3.8 and 3.4 for reader 2 compared with single-energy CTA results of 4.5 and 4.2 for reader 1 and 4.5 and 4.1 for reader 2. Low-energy virtual monochromatic images (40-60 keV) from reduced-iodine-dose (28%) dual-energy CTA had significantly higher intravascular aortic attenuation (26-185%) and contrast-to-noise ratio (CNR) (20-25%) than standard-iodine-dose single-energy CTA images (p < 0.0001). No significant difference was found between patients who received 270 and those who received 320 mg I/mL with respect to intravascular aortic attenuation (p = 0.6331) or CNR (p = 0.9775).

CONCLUSION

Low-energy virtual monochromatic imaging datasets from reduced-iodine (24 g I) single-source dual-energy CTA of the abdomen provide up to 185% higher attenuation and 25% higher CNR than standard-iodine-dose (33.3 g I) single-energy CTA while offering a wide range of energy settings irrespective of the concentration of IV contrast medium used.

A Novel Attempt to Standardize Results of CFD Simulations Basing on Spatial Configuration of Aortic Stent-Grafts

Currently, studies connected with Computational Fluid Dynamic (CFD) techniques focus on assessing hemodynamic of blood flow in vessels in different conditions e.g. after stent-graft’s placement. The paper propose a novel method of standardization of results obtained from calculations of stent-grafts' “pushing forces” (cumulative WSS—Wall Shear Stress), and describes its usefulness in diagnostic process. AngioCT data from 27 patients were used to reconstruct 3D geometries of stent-grafts which next were used to create respective reference cylinders. We made an assumption that both the side surface and the height of a stent-graft and a reference cylinder were equal. The proposed algorithm in conjunction with a stent-graft “pushing forces” on an implant wall, allowed us to determine which spatial configuration of a stent-graft predispose to the higher risk of its migration. For stent-grafts close to cylindrical shape (shape factor φ close to 1) WSS value was about 267Pa, while for stent-grafts different from cylindrical shape (φ close to 2) WSS value was about 635Pa. It was also noticed that deformation in the stent-graft’s bifurcation part impaired blood flow hemodynamic. Concluding the proposed algorithm of standardization proved its usefulness in estimating the WSS values that may be useful in diagnostic process. Angular bends or tortuosity in bifurcations of an aortic implant should be considered in further studies of estimation of the risk of implantation failure.

Experience With Fenestrated Endovascular Repair of Juxtarenal Abdominal Aortic Aneurysms at a Single Center

To present the early and mid-term results of fenestrated endovascular aneurysm repair (FEVAR) using the Zenith fenestrated device for juxtarenal abdominal aortic aneurysms (JAAAs) at our center in China.

DESIGN

Retrospective study.The study included 15 male patients with JAAAs, who underwent FEVAR using the Zenith fenestrated device at our center between February 2011 and June 2015.All custom-made Zenith fenestrated devices were designed according to computed tomography angiography (CTA) images obtained preoperatively. The patients with renal insufficiency underwent duplex ultrasonography, while the patients with normal renal function underwent 3 CT data acquisitions including nonenhanced CT, arterial phase, and venous phase. These examinations and blood examinations were completed at 3, 6, and 12 months after discharge, and annually thereafter.The mean age of the patients was 73.13 ± 9.06 years (range, 57-86 years), and the median follow-up period was 30 months (8-52 months). Small fenestrations were used in 27 renal arteries, scallops were used in 7 superior mesenteric arteries (SMAs) and 2 renal arteries, and large fenestrations were used in 2 SMAs. Conversion to an open procedure was not required in any of the patients, and the technical success rate was 100%. The mean length of hospital stay was 11.33 ± 2.02 days (7-15 days). No patient died within the 1st 30 days after the operation. One patient had a type Ia endoleak, which disappeared at 6 months after the operation, 1 patient had a type Ib endoleak, which was detected at 17 months after the operation, and 2 patients had type II endoleaks. One patient died at 17 months and another patient died at 30 months after the operation. Therefore, the all-cause mortality rate was 13.33% (2/15). The target vessel patency rate was 100% without occlusion.The early and mid-term results of FEVAR using the Zenith fenestrated device were good, demonstrating that this procedure is effective for the treatment of JAAAs.

Management of a dislocated endovascular aneurysm repair in a challenging giant abdominal aortic aneurysm

Introduction A case report of a contained rupture of an abdominal aneurysm, treated by endovascular technique (EVAR), but complicated by perioperative endoprosthesis limb dislocation. Case report An 81-year old male presented at the emergency department with a contained rupture of an infrarenal aortic aneurysm and bilateral extensive iliac aneurysmatic disease. Open repair was no option, due to the pulmonary condition. The patient was prepped for an emergency EVAR. After placing a bifurcated endoprosthesis, angiography revealed a type IIIa endoleak, due to a dislocation between two left iliac extensions. We converted to a right-sided aorto-uni-iliac endoprosthesis with a femorofemoral bypass. A postoperative CT-scan showed a complete exclusion of the aneurysm, a patent aorto-uni-iliac endoprosthesis and a femorofemoral bypass without an endoleak. Discussion EVAR is feasible with a hostile neck AAA, even in a ruptured AAA. In large AAA, one should consider an overlap larger than suggested in the instructions for use.

Predictive Factors for the Development of Type 2 Endoleak Following Endovascular Aneurysm Repair

Type 2 endoleak (T2EL) is the most common complication following endovascular aneurysm repair (EVAR) for abdominal aortic aneurysms. The management of T2ELs is controversial due to the relatively low incidence of negative outcomes when secondary intervention is avoided. Some studies challenge this practice as demonstrated by adverse events following conservative treatment of T2ELs. Evidence has shown that the preoperative computed tomographic angiogram can predict the development of T2EL based on a patient's arterial anatomy, specifically vessels associated with increased rates of post-EVAR endoleak development. Preoperative embolization of those aortic branch vessels associated with T2ELs has shown decreased rates of postoperative complications and may result in a decreased need for surveillance and reintervention.

Magnetic Resonance Imaging with a Weak Albumin Binding Contrast Agent can Reveal Additional Endoleaks in Patients with an Enlarging Aneurysm after EVAR

OBJECTIVES/BACKGROUND

To examine the additional diagnostic value of magnetic resonance imaging (MRI) after administration of a weak albumin binding contrast agent in post-endovascular aneurysm repair (EVAR) patients with aneurysm growth with no or uncertain endoleak after computed tomography angiography (CTA).

METHODS

This was a prospective diagnostic cross sectional study carried out between April 2011 and August 2013. MRI was performed in all patients with aneurysm growth≥5 mm after EVAR implantation and no or uncertain endoleak on CTA, or the inability, on CTA, to identify the source of a visible endoleak. All MRI scans were performed on a 1.5 T clinical MRI scanner after administration of a weak albumin binding contrast agent. The presence of endoleaks was assessed by visually comparing pre- and post-contrast T1-weighted images with fat suppression. Post-contrast images were acquired 5 and 15 minutes after contrast administration.

RESULTS

Twenty-nine patients (26 men; 90%) with a median age of 74 years (interquartile range [IQR] 67-76) were included. The median interval between EVAR and MRI was 39 months (IQR 20-50). The median increase in maximum aneurysm diameter during total follow up after EVAR was 11 mm (IQR 6-17). At CTA, 16 patients (55%) had no detectable endoleak, five patients (17%) had suspected but uncertain endoleak, and eight patients had a definite endoleak (28%). On the post-contrast MRI images, endoleak was observed in 24 patients (83%). In all patients with uncertain endoleak on CTA, endoleak was detected with MRI. For type II endoleaks, feeding vessels were detected in 22/23 patients (96%) and these were all, except one, lumbar arteries.

CONCLUSION

In patients with enlarging aneurysms of unknown origin after EVAR, MRI with a weak albumin binding contrast agent has additional value for both the detection and determination of the origin of the endoleak.

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.

Interventional radiology: a half century of innovation

The evolution of modern interventional radiology began over half century ago with a simple question. Was it possible to use the same diagnostic imaging tools that had revolutionized the practice of medicine to guide the real-time treatment of disease? This disruptive concept led to rapid treatment advances in every organ system of the body. It became clear that by utilizing imaging some patients could undergo targeted procedures, eliminating the need for major surgery, while others could undergo procedures for previously unsolvable problems. The breadth of these changes now encompasses all of medicine and has forever changed the way we think about disease. In this brief review article, major advances in the field, as chronicled in the pages of Radiology, will be described.

Potential of mesenchymal stem cell in stabilization of abdominal aortic aneurysm sac

BACKGROUND

In their origin, abdominal aortic aneurysms (AAAs) are related to an inflammatory reaction within the aortic wall, which can lead to weakness and degeneration of this structure. One of the most widely accepted treatment modalities for AAAs is the placement of stent grafts. Nevertheless, in some patients blood re-enters the aneurysm sac, creating so-called leaks, which constitute a renewed risk of rupture and death.This study explores the possibility of filling aneurysm sacs treated by endovascular aneurysm repair with adipose tissue-derived mesenchymal stem cells (ASCs) in a porcine model.

METHODS

We developed a porcine model using 22 animals by creating an artificial AAA made with a Dacron patch. AAAs were then treated with a coated stent that isolated the aneurysm sac, after which we introduced allogeneic ASC into the sac. Animals were followed-up for up to 3 mo. The experiment consisted of the aforementioned surgical procedure performed first, followed by computed tomography and echo-Doppler imaging during the follow-up, and finally, after sacrificing the animals, histologic analysis of tissue samples from the site of cell implantation by a blinded observer and the detection of implanted cells by immunofluorescence detection of the Y chromosome.

RESULTS

Our findings demonstrate the survival of ASCs over the 3 mo after implantation and histologic changes associated with this treatment. Treated animals had less acute and chronic inflammation throughout the study period, and we observed increasing fibrosis of the aneurysm sac, no accumulation of calcium, and a regeneration of elastic fibers in the artery.

CONCLUSIONS

The combination of endovascular aneurysm repair and cell therapy on AAAs has promising results for the stabilization of the sac, resulting in the generation of living tissue that can secure the stent graft and even showing some signs of wall regeneration. The therapeutic value of such cell-based therapy will require further investigation.

Finite element analysis of the mechanical performances of 8 marketed aortic stent-grafts

PURPOSE

To assess numerically the flexibility and mechanical stresses undergone by stents and fabric of currently manufactured stent-grafts.

METHODS

Eight marketed stent-graft limbs (Aorfix, Anaconda, Endurant, Excluder, Talent, Zenith Flex, Zenith LP, and Zenith Spiral-Z) were modeled using finite element analysis. A numerical benchmark combining bending up to 180° and pressurization at 150 mmHg of the stent-grafts was performed. Stent-graft flexibility, assessed by the calculation of the luminal reduction rate, maximal stresses in stents, and maximal strains in fabric were assessed.

RESULTS

The luminal reduction rate at 90° was <20% except for the Talent stent-graft. The rate at 180° was higher for Z-stented models (Talent, Endurant, Zenith, and Zenith LP; range 39%-78%) than spiral (Aorfix, Excluder, and Zenith Spiral-Z) or circular-stented (Anaconda) devices (range 14%-26%). At 180°, maximal stress was higher for Z-stented stent-grafts (range 370-622 MPa) than spiral or circular-stented endografts (range 177-368 MPa). At 90° and 180°, strains in fabric were low and did not differ significantly among the polyester stent-grafts (range 0.5%-7%), while the expanded polytetrafluoroethylene fabric of the Excluder stent-graft underwent higher strains (range 11%-18%).

CONCLUSION

Stent design strongly influences mechanical performances of aortic stent-grafts. Spiral and circular stents provide greater flexibility, as well as lower stress values than Z-stents, and thus better durability.

Preoperative inferior mesenteric artery embolization before endovascular aneurysm repair: decreased incidence of type II endoleak and aneurysm sac enlargement with 24-month follow-up

PURPOSE

To review the effect of preoperative embolization of the inferior mesenteric artery (IMA) before endovascular aneurysm repair (EVAR) on subsequent endoleaks and aneurysm growth.

MATERIALS AND METHODS

Between August 2002 and May 2010, 108 patients underwent IMA embolization before EVAR. Coil embolization was performed in all patients in whom the IMA was successfully visualized and accessed during preoperative conventional angiography. In this cohort, the incidences of type II endoleak, aneurysm sac volume enlargement at 24 months, and repeat intervention were compared with a group of 158 consecutive patients with a patent IMA on preoperative computed tomography angiography but not on conventional angiography, who therefore did not undergo preoperative embolization.

RESULTS

The incidence of type II endoleak was significantly higher in patients not treated with embolization (49.4% [78 of 158] vs 34.3% [37 of 108]; P = .015). The incidence of secondary intervention for type II endoleak embolization was also significantly higher in those who did not undergo embolization (7.6% [12 of 158] vs 0.9% [one of 108]; P = .013). At 24 months, an increase in aneurysm sac volume was observed in 47% of patients in the nonembolized cohort (21 of 45), compared with 26% of patients in the embolized cohort (13 of 51; P = .03). No aneurysm ruptures or aneurysm-related deaths were observed in either group. One patient in the embolization group developed mesenteric ischemia and ultimately died.

CONCLUSIONS

Preoperative embolization of the IMA was associated with reduced incidences of type II endoleak, aneurysm sac volume enlargement at 24 months, and secondary intervention.

The use of rapid endovascular balloon occlusion in unstable patients with ruptured abdominal aortic aneurysm

OBJECTIVE

: To present our results and demonstrate advantages of rapid endovascular balloon occlusion (REBO) of the juxtarenal aorta in unstable patients with ruptured abdominal aortic aneurysm (rAAA).

METHODS

: Since 2006, all unstable patients with rAAA are immediately transferred to the operating room (OR). No computed tomography scan is performed once diagnosis is made on ultrasound examination. Instability is defined as systolic blood pressure less than 60 mm Hg, unconsciousness, cardiac ischemia, or intubation. Once arrived in the OR, a Reliant aortic balloon is introduced and inflated at the level of the renal arteries. Subsequently, an angiogram is made through the contralateral femoral artery in order to decide between open or endovascular repair (EVAR).

RESULTS

: Twelve patients with rAAA were defined as unstable. REBO was installed within 10 minutes after arrival in the OR. Aortic occlusion resulted in immediate hemodynamic stability. Five patients were suitable for EVAR. Seven patients had open repair. For these abdominal dissection was more careful since no instability was encountered. All patients survived the procedure except one. Mean stay on intensive care unit was 19.7 days for open group and 8.4 for EVAR.

CONCLUSIONS

: REBO of the juxtarenal abdominal aorta by pc technique in unstable patients with rAAA resulted in a 17% 30-day mortality and a 100% 1-year event-free follow-up for survivors. With this technique, EVAR exclusion is still a valuable treatment. Exposure and decision making for the open group is easier to perform with less risk for additional damaging to neighboring structures during dissection since urgent cross-clamping is not necessary.

[Endoleaks - when is treatment necessary?]

Currently the majority of infrarenal abdominal aortic aneurysm repairs are endovascular procedures using a stent graft. This method continues to be questioned due to an up to 50 % incidence of endoleaks, i.e. the postinterventional persistence of blood flow outside the graft and within the aneurysm sac, potentially bearing the risk of a further increase of the aneurysm diameter and aneurysm rupture. Currently a total of five different endoleak types can be distinguished. Multiphase computed tomography (CT) is the standard imaging method for the detection and classification of endoleaks or alternatively contrast-enhanced ultrasound can be used. The different types of endoleak have very different therapeutic implications. In direct endoleaks (types I and III) the systemic blood pressure is directly transferred to the aneurysm wall which carries a high risk of rupture and in general an immediate intervention is indicated. Indirect endoleaks (types II, IV and V) take a more benign course and in the majority of cases treatment is only necessary when further aneurysm expansion occurs.

[Review of pre- and post-treatment multidetector computed tomography findings in abdominal aortic aneurysms]

The increase in the frequency of abdominal aortic aneurysms (AAA) and the widely accepted use of endovascular aneurysm repair (EVAR) as a first-line treatment or as an alternative to conventional surgery make it necessary for radiologists to have thorough knowledge of the pre- and post-treatment findings. The high image quality provided by multidetector computed tomography (MDCT) enables CT angiography to play a fundamental role in the study of AAA and in planning treatment. The objective of this article is to review the cases of AAA in which CT angiography was the main imaging technique, so that radiologists will be able to detect the signs related to this disease, to diagnose it, to plan treatment, and to detect complications in the postoperative period.

Quality improvement guidelines for imaging detection and treatment of endoleaks following endovascular aneurysm repair (EVAR)

Major concerns after aortic aneurysm repair are caused by the presence of endoleaks, which are defined as persistent perigraft flow within the aortic aneurysm sac. Diagnosis of endoleaks can be performed with various imaging modalities, and indications for treatment are based on further subclassifications. Early detection and correct classification of endoleaks are crucial for planning patient management. The vast majority of endoleaks can be treated successfully by interventional means. Guidelines for Imaging Detection and Treatment of endoleaks are described in this article.

Multi-detector CT angiographic imaging in the follow-up of patients after endovascular abdominal aortic aneurysm repair (EVAR)

BACKGROUND

Multidetector computed tomography (MDCT) angiography represents the standard of reference in the follow-up of patients after endovascular abdominal aortic aneurysm repair (EVAR), being effective in the detection of the full spectrum of possible complications on both axial and 3D images.

METHODS

The purpose of this article is to review the normal CT angiography findings of the different types of stent-grafts and to describe the radiological findings of early and late complications after EVAR on axial and reconstructed images. A selection of cases of post-EVAR MDCT angiography is presented to learn the techniques most commonly used for endovascular treatment, the correct CT scanning technique to acquire the data, the full gamut of possible procedure-related complications and how these complications usually appear on CT images.

CONCLUSION

MDCT angiography is an effective and specific technique in both the pre- and postoperative settings of EVAR procedures. A better understanding of the procedure, the devices, the normal postoperative imaging features and the possible procedure-related complications ensures optimal planning and follow-up of patients undergoing an EVAR procedure.

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.

Clinical efficacy of endovascular abdominal aortic aneurysm repair

BACKGROUND

Endovascular aortic aneurysm repair (EVAR) has come into use and been widely extended because of the low complication rate and less-invasiveness. This article aimed to describe our experience in the treatment of abdominal aortic aneurysm with EVAR.

MATERIALS AND METHODS

A retrospective review was conducted for the 22 patients who underwent EVAR in a single hospital December 2001 to June 2009.

RESULTS

The mean age of the patients was 68.5±7.6 years. There were several risk factors and comorbidities in 20 patients (90.9%). The mean diameter of the aortic aneurysms was 61.2±12.9 mm. The mean length, diameter, and angle of the aneurysmal neck were 30.5±15.5 mm, 24.0±4.5 mm, and 43.9±16.0°, respectively. The mean follow-up period of the patients was 28.8±29.5 months. The 30-day postoperative mortality was none. Seven patients (31.8%) had endoleaks during the hospital stay and three patients (13.6%) had endoleaks during the follow-up period. One patient (4.5%) died due to a ruptured aortic aneurysm. The cumulative patient survival rates were 88.2%, 88.2%, and 70.6% at 1, 3, and 5 years of follow-up, respectively.

CONCLUSION

EVAR is currently a safe, feasible procedure for high risk patients with abdominal aortic aneurysm because of low postoperative complication and mortality if patients are selected properly and followed up carefully.

Pseudoaneurisma de carótida comum secundário a trauma contuso: opção de tratamento por cirurgia a céu aberto

Relato de caso de paciente feminina, com 44 anos de idade, vítima de trauma cervical em acidente de trânsito, que apresentou massa cervical dolorosa, rouquidão e disfagia associados, três semanas após o trauma. Exames complementares identificaram pseudoaneurisma de carótida comum em zona II. Optou-se pelo tratamento por meio de cirurgia convencional a céu aberto com excelente resultado imediato. Foi realizado um exame de controle após sete meses do procedimento cirúrgico, e os resultados confirmaram o sucesso terapêutico.

A complication of open abdominal aortic aneurysm repair closely resembling a type II endoleak

Endoleak is a well-recognized complication of endovascular treatment of abdominal aortic aneurysms. Despite over 40 years of open transabdominal aortic aneurysm surgery, only in the last decade has endoleak as a complication of open surgery been described. Endoleak after conventional open surgery was first described by Chan et al in 2000 and remains a rare complication. We describe the first reported case of type II endoleak (back-bleeding inferior mesenteric artery) after open repair of abdominal aortic aneurysm, and its successful management by endovascular coil embolization.

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.