Could Four-dimensional Contrast-enhanced Ultrasound Replace Computed Tomography Angiography During Follow up of Fenestrated Endografts? Results of a Preliminary Experience

New Preloaded System for Renal and Visceral Arteries in Fenestrated Endografting

AIM/BACKGROUND

The New Preloaded System (NPS) for renal/visceral arteries (TVVs) is an emerging technology in fenestrated endografting (FEVAR) that allows TVVs cannulation and stenting through the same access of the endograft main body. However, only few preliminary experiences are currently available in the literature. The aim of this study is to report the outcomes of NPS-FEVAR in juxta/para-renal (J/P-AAAs) and thoracoabdominal (TAAAs) aneurysms repair.

METHODS

This is a prospective (NCT05224219), single-center/observational study of patients submitted to NPS-FEVAR for J/PAAAs and TAAAs between 2019 and 2022 (July). Definitions and outcomes were evaluated according to the current SVS-reporting standard. Technical success (TS) and TS preloaded related, spinal cord ischemia (SCI), and 30-day mortality were assessed as early endpoints. Survival, freedom from reinterventions (FFRs), and freedom from TTVs-instability (FFTVVs-instability) were analyzed during follow-up.

RESULTS

Among 157 F/B-EVAR cases, 74 (47%) NPS-FEVAR were planned and enrolled in the study [48 (65%) J/P-AAAs; 26 (35%) TAAAs]. The main indication for NPS-FEVAR was the presence of a hostile iliac axis (54%-73%) or the necessity of expeditious pelvic/lower-limb reperfusion for SCI prevention in TAAAs (20%-27%). Overall, 292 TVVs were accommodated by 289 fenestrations and 3 branches; 188 of 289 (65%) fenestrations were preloaded. NPS-FEVAR configuration was from "below" and "from below to above" in 28 (38%) and 46 (62%) cases, respectively. TS and TS preloaded system-related was 96% (71/74) and 99% (73/74), respectively. Target visceral vessels patency at the completion angiography was 99% (290/292). Failures were 2 renal arteries loss and 1 massive bleeding from a percutaneous closure system breakage. The latter patient developed postoperative multiorgans failure and died on the fifth postoperative day, causing only 30-day/in-hospital mortality (1.3%). One (1.3%) patient with a JAAA and preoperative bilateral occlusion of the hypogastric arteries suffered SCI. The median follow-up was 14 (IQR: 8) months. The estimated 3-year survival was 91% with no aneurysm-related mortality during follow-up. The estimated 3-year FFR and FFTVVs-instability were 85 and 92%, respectively.

CONCLUSION

New preloaded system FEVAR is a safe and effective option in the treatment of J/PAAAs and TAAAs in the presence of hostile iliac access or to guarantee an expeditious pelvic/lower limb reperfusion, leading to satisfactory results in terms of TS, early and mid-term clinical outcomes.Clinical ImpactNew preloaded system for fenestrated and branched endografting allows to increase the feasibility of the advanced endovascular aortic repair in challenging iliac access, thoracoabdominal aneurysm repair and reduce difficulties in target visceral vessels cannulation.

Ultrasound Coded-Excitation Imaging for Endoleak Detection After Complex Endovascular Aortic Repair

OBJECTIVES

Several imaging modalities have been suggested for surveillance after fenestrated endovascular aortic repair in general and endoleak detection in specific. In the present project a coded excitation-based ultrasound (B-Flow) was investigated for endoleak detection after complex endovascular aortic repair.

METHODS

Patients post complex endovascular aortic repair (FEVAR or T/FEVAR) undergoing follow-up appointments including ultrasonography of the aorta at a vascular and endovascular surgery outpatient center were included in the study. B-Flow was compared with computed tomography angiography (CTA), Duplex ultrasound (DUS), and contrast-enhanced ultrasound (CEUS) regarding agreement and reliability for endoleak detection and characterization.

RESULTS

In total, 47 follow-ups were included. They accumulated in a total of 149 imaging investigations. Endoleaks were discovered in 44.7% of B-Flow studies and a majority of these endoleaks were classified as type II. Agreement between B-Flow and other imaging modalities was good (>80.0%) in general. However, with B-Flow 6 and 2 endoleaks would have been missed compared with CEUS and CTA, respectively. Regarding endoleak classification, B-Flow had a strong agreement (94.5%) with CEUS in detected cases. Furthermore, in a limited subset analysis, imaging findings were externally validated using findings from angiography.

CONCLUSIONS

Ultrasonography allows for endoleak detection and characterization without an invasive procedure or the use of potentially nephrotoxic contrast medium and can reduce radiation exposure. While CEUS mitigates issues of radiation and nephrotoxicity it still requires the intravenous application of contrast enhancers. Ultrasound coded-excitation imaging such as B-Flow could therefore further simplify endoleak surveillance after fenestrated endovascular aortic repair.

Editor's Choice -- European Society for Vascular Surgery (ESVS) 2024 Clinical Practice Guidelines on the Management of Abdominal Aorto-Iliac Artery Aneurysms

OBJECTIVE

The European Society for Vascular Surgery (ESVS) has developed clinical practice guidelines for the care of patients with aneurysms of the abdominal aorta and iliac arteries in succession to the 2011 and 2019 versions, with the aim of assisting physicians and patients in selecting the best management strategy.

METHODS

The guideline is based on scientific evidence completed with expert opinion on the matter. By summarising and evaluating the best available evidence, recommendations for the evaluation and treatment of patients have been formulated. The recommendations are graded according to a modified European Society of Cardiology grading system, where the strength (class) of each recommendation is graded from I to III and the letters A to C mark the level of evidence.

RESULTS

A total of 160 recommendations have been issued on the following topics: Service standards, including surgical volume and training; Epidemiology, diagnosis, and screening; Management of patients with small abdominal aortic aneurysm (AAA), including surveillance, cardiovascular risk reduction, and indication for repair; Elective AAA repair, including operative risk assessment, open and endovascular repair, and early complications; Ruptured and symptomatic AAA, including peri-operative management, such as permissive hypotension and use of aortic occlusion balloon, open and endovascular repair, and early complications, such as abdominal compartment syndrome and colonic ischaemia; Long term outcome and follow up after AAA repair, including graft infection, endoleaks and follow up routines; Management of complex AAA, including open and endovascular repair; Management of iliac artery aneurysm, including indication for repair and open and endovascular repair; and Miscellaneous aortic problems, including mycotic, inflammatory, and saccular aortic aneurysm. In addition, Shared decision making is being addressed, with supporting information for patients, and Unresolved issues are discussed.

CONCLUSION

The ESVS Clinical Practice Guidelines provide the most comprehensive, up to date, and unbiased advice to clinicians and patients on the management of abdominal aorto-iliac artery aneurysms.

Outcomes of Directional Branches of the T-Branch Off-the-Shelf Multi-Branched Stent-Graft

Background: A controversy on bridging covered stent (BCS) choice, between self-expanding (SECS) and balloon-expandable (BECS) stents, still exists in branched endovascular repair. This study aimed to determine the primary target vessel (TV) patency in patients treated with the t-Branch device and identify factors impairing the outcomes. Methods: A retrospective study was undertaken, including patients treated with the t-Branch (Cook Medical, Bloomington, IN, USA) between 2014 and 2019 (early 2014–2016; late 2017–2019). The endpoint was the primary patency (CT: celiac trunk, SMA, superior mesenteric artery, RRA: right renal artery, LRA: left renal artery) during the follow-up. Any branch instability event was assessed. The factors affecting the patency were determined using multivariable regression models and Kaplan–Meier analyses. Results: In total, 2018 TVs were analyzed; 1542 SECSs and 476 BECSs. The CT patency was 99.8% (SE 0.2%) at the 1st month, with no other event. The SMA patency was 97.8% (SE 1) at the 12th month. The RRA patency was 96.7% (SE 2) at the 24th month. The LRA patency was 99% (SE 0.4) at the 6th month. Relining was the only factor independently associated with the SMA patency (OR 8.27; 95% CI 1.4–4.9; p = 0.02). The freedom from instability was 62% (SE 4.3%) and 45% (SE 5.4%) at the 24th month and 36th month. No significant difference was identified between the BECSs and SECSs in the early or late experience. Conclusion: BCS for the t-Branch branches performed with a good primary patency during the short-term follow-up. The type of BCS did not influence the patency. Relining might be protective for SMA patency.

Feeding Vessel Ablation: A Novel Subsegmental Devascularization Technique for the Treatment of Hepatocellular Carcinoma Located at the Liver Marginal Angle

This pilot clinical study evaluated primarily the efficacy of feeding vessel ablation (FVA) in the treatment of hepatocellular carcinoma (HCC) located at the liver marginal angle (LMA). Nine patients with nine unresectable HCC lesions were prospectively included in this study. The target tumors (mean: 3.0 cm, interquartile range: 2.4-3.6 cm) were located at the LMA (segment 2/3/6) and adjacent to the gastrointestinal tract. Artificial ascites was attempted and failed. Multimode ultrasound technologies, including 2-D and real-time 3-D contrast-enhanced ultrasound, were used to identify the morphology and structure of the feeding vessels for the target tumors. During the treatment, a unipolar cool-tip electrode was used to ablate the feeding vessels, and the target ablation point was set in subsegmental or more distal vessels to induce a downstream ischemia region. Therapeutic outcomes were assessed after FVA, including the rates of technical success, tumor response, local tumor progression (LTP), overall survival (OS) and major complications. Cumulative LTP and OS were estimated with the Kaplan-Meier method. The technical success rate determined immediately after radiofrequency ablation was 7 of 9 (77.8%). Complete response (CR) was achieved in 7 of 7 tumors (100%) at the 1-mo evaluation. During a median follow-up period of 15.6 mo (range: 4.3-53.3 mo), CR remained in 6 of 7 tumors (85.7%), with LTP observed in 1 of 7 tumors (14.3%) 4.7 mo after treatment. The cumulative 1-, 3- and 5-y LTP-free rates were all 83.3%, and the cumulative 1-, 3- and 5-y OS rates were 42.9%, 28.6% and 0%, respectively. No major complications occurred. We concluded that FVA can induce subsegmental devascularization and has the potential to serve as an effective and safe alternative technique for local control of unresectable HCC located at the LMA when artificial ascites fails.

Contrast Ultrasound, Sonothrombolysis and Sonoperfusion in Cardiovascular Disease: Shifting to Theragnostic Clinical Trials

Contrast ultrasound has a variety of applications in cardiovascular medicine, both in diagnosing cardiovascular disease as well as providing prognostic information. Visualization of intravascular contrast microbubbles is based on acoustic cavitation, the characteristic oscillation that results in changes in the reflected ultrasound waves. At high power, this acoustic response generates sufficient shear that is capable of enhancing endothelium-dependent perfusion in atherothrombotic cardiovascular disease (sonoperfusion). The oscillation and collapse of microbubbles in response to ultrasound also induces microstreaming and jetting that can fragment thrombus (sonothrombolysis). Several preclinical studies have focused on identifying optimal diagnostic ultrasound settings and treatment regimens. Clinical trials have been performed in acute myocardial infarction, stroke, and peripheral arterial disease often with improved outcome. In the coming years, results of ongoing clinical trials along with innovation and improvements in sonothrombolysis and sonoperfusion will determine whether this theragnostic technique will become a valuable addition to reperfusion therapy.

Reinterventions after fenestrated and branched endografting for degenerative aortic aneurysms

OBJECTIVE

Fenestrated/branched endovascular abdominal aortic aneurysm repair (F/B-EVAR) is widely accepted technique to treat juxta/pararenal abdominal aortic aneurysms (J/P-AAAs) and thoracoabdominal aortic aneurysms (TAAAs) for patients at high-surgical risk. However, the follow-up results should be carefully evaluated, especially in terms of the reintervention rate. The aim of the present study was, therefore, to evaluate the early and mid-term reinterventions after FB-EVAR for J/P-AAAs and TAAAs and their effects on follow-up survival.

METHODS

From 2006 to 2019, all consecutive patients who had undergone F/B-EVAR for J/P-AAAs or TAAAs were prospectively enrolled. Cases requiring reinterventions were retrospectively analyzed. Patients with aortic dissection were excluded from the present analysis. Reinterventions were classified as follows: access related, aortoiliac related, or target visceral vessel (TVV) related. Freedom from reintervention and survival were assessed using the Kaplan-Meier method, and univariate and multivariate analyses were used to determine the risk factors.

RESULTS

Overall, 221 F/B-EVAR procedures were performed for 111 J/P-AAAs (50.3%) and 110 TAAAs (49.7%) in an elective (182; 82%) or urgent (39; 18%) setting. The median follow-up was 27 months (interquartile range, 13 months). Overall, 41 patients had undergone 52 reinterventions (single, 30 [14%]; multiple, 11 [5%]; access related, 17 [33%]; aortoiliac related, 6 [12%]; TVV related, 29 [55%]). Of the 52 reinterventions, 32 (62%) and 20 (38%) had occurred within and after 30 days, respectively. Eight reinterventions (15%) had been were performed in an urgent setting. Endovascular and open reinterventions were performed in 32 (62%) and 20 (38%) cases, respectively. Open reinterventions were frequently access related (access, 16; no access, 4; P ≤ .001). Technical success was 95% (39 patients); failures consisted of one splenic artery rupture and one renal artery loss. Patients undergoing reintervention had more frequently undergone a primary urgent F/B-EVAR (urgent, 12 of 39 [31%]; elective, 29 of 182 [16%]; P < .001) and had had TAAAs (TAAAs, 34 of 41 [83%]; J/P-AAAs, 7 of 41 [17%]; P < .001). The patients with TAAAs had had a greater incidence of TVV-related reintervention (TAAAs, 26 of 28 [93%]; J/P-AAAs, 2 of 28 [7%]; P < .001) and multiple reinterventions (TAAAs, 9 of 11 [82%]; J/P-AAAs, 2 of 11 [18%]; P = .03) compared with those with J/P-AAAs. Survival at 3 years was 75%. Freedom from reintervention was 81% at 3 years. Patients who had undergone reinterventions had lower 3-year survival (reintervention, 61%; no reintervention, 77%; P = .02). Preoperative chronic renal failure (hazard ratio [HR], 2.0; 95% confidence interval [CI], 1.1-3.6; P = .02), TAAAs (HR, 2.3; 95% CI, 1.1-4.8; P = .03), and urgent primary F/B-EVAR procedures (HR, 2.5; 95% CI, 1.2-4.9; P = .01) were independent predictors of late mortality.

CONCLUSIONS

Reinterventions after F/B-EVAR are not uncommon and were related to TVVs in only one half of cases. Most of them can be performed in an elective setting using endovascular techniques. The technical success rate was excellent. Reinterventions were more frequent after TAAAs and urgent F/B-EVAR procedures and had a significant effect on overall survival in these situations.

The Utility of Intraoperative Contrast-enhanced Ultrasound for Immediate Treatment of Type Ia Endoleak during EVAR: Initial Experience

Objectives:

Type Ia endoleak (EL) after endovascular abdominal aortic repair (EVAR) may be misdiagnosed at completion angiography. Intraoperative contrast-enhanced ultrasound (CEUS) may play a role in early detection and immediate treatment of type Ia EL.

Methods:

From January 2017 to April 2018, patients treated with EVAR underwent intraoperative CEUS. After endograft deployment and ballooning, digital subtraction angiography (DSA) and intraoperative CEUS were performed in a blinded fashion. All cases of type Ia EL at DSA or CEUS were considered.

Results:

Type Ia EL detected at intraoperative CEUS and undetected at DSA was defined in 2 patients. The former was solved with intraoperative re-ballooning; in the latter case, a Palmaz stent deployment was required. The resolution of type Ia EL was detected at intraoperative CEUS control and post-operative computed tomography angiography (CTA). In another patient, the DSA detected a type Ia EL, but intraoperative CEUS reveal a type II EL from lumbar arteries. Post-operative CTA confirm the type II EL.

Conclusions:

The reported cases prove the clinical utility of the intraoperative CEUS, permitting the early identification of 2 type Ia EL. In addition, the intraoperative CEUS is useful in case of dubious type Ia EL at DSA, avoiding unnecessary intraoperative adjunctive procedure or post-operative CTA. (www.actabiomedica.it)

Duplex Ultrasound Can Successfully Identify Endoleaks and Renovisceral Stent Patency in Patients Undergoing Complex Endovascular Aneurysm Repair

Efficacy of duplex ultrasound (DU) surveillance of complex EVAR such as FEVAR and ChEVAR has not been studied. All patients undergoing FEVAR or ChEVAR at a single multihospital institution were retrospectively reviewed. Postoperative surveillance included DU at 1 month and CTA at 3 months. 82 patients met inclusion criteria including 39 (47.6%) ChEVAR and 43 (52.4%) FEVAR cases. DU identified endoleak with aneurysm sac enlargement in 3 cases requiring reintervention. CTA at 3 months detected 2 new endoleaks without growth and 1 renal artery stent occlusion. Replacement of initial postoperative imaging with DU did not result in any missed endoleaks, deaths, ruptures, or branch occlusions.

Fenestrated endografting is the preferred option for juxta-renal aortic aneurysm reconstruction

BACKGROUND

The aim of this study was to report early/mid-term-up outcomes of fenestrated endografting (FEVAR) for juxta-renal aneurysms (j-AAAs).

METHODS

Between 2008 and 2019, all consecutive j-AAAs treated by FEVAR were prospectively collected and retrospectively analyzed. Early endpoints were technical success, renal function worsening and 30-day mortality. Follow-up endpoints were survival, freedom from re-interventions (FFRs) and target visceral vessels (TVVs) patency.

RESULTS

Among 240 cases of FB-EVAR, 98(41%) were j-AAAs. Endografts with 1,2,3,4 and 5 fenestrations were planned in 3(3%), 25(26%), 35(36%), 33(34%) and 2(1%) cases, respectively. Overall, 360 TVVs were treated by fenestrations and scallops. Technical success was achieved in 97(99%) cases. The only failure was 1 type III endoleak requiring renal artery relining. No TVVs were lost. Renal function worsening was reported in 22(22%) and 12(12%) cases at 24-hour and 30-day, respectively. One patient required hemodialysis and died within 30-day (1%). This was the only case of 30-day mortality. The mean follow-up was 36±32months. Aneurysm sac shrinkage or stability was observed in 55(56%) and 41(42%) cases, respectively. Two (2%) patients with persistent type II endoleak had sac enlargement and required re-interventions. Freedom from reinterventions at 5-year was 86%. An asymptomatic celiac trunk occlusion (accommodated by a scallop) occurred at 24-month in a case with a severe preoperative stenosis. No late renal arteries occlusions or type I-III endoleaks occurred. TVVs-patency was 96% at 5-year. Renal function worsening was reported in 10(10%) patients during follow-up. Survival at 5-year was 73%, with no j-AAA related mortality. Chronic obstructive pulmonary disease (COPD) (P=0.007; OR:4.8; 95% CI: 1.5-15.3) and postoperative renal function worsening (P=0.028; OR:1,1; 95% CI: 1.1-1.2) were independent predictor for mortality at the multivariate analysis.

CONCLUSIONS

FEVAR for j-AAAs is safe and effective at early and long-term follow-up. According with these results, it could be proposed as the first line treatment in high risk patients if anatomically fit. Long term survival is reduced in the presence of preoperative COPD and postoperative renal function worsening.

Intraoperative contrast-enhanced ultrasound for early diagnosis of endoleaks during endovascular abdominal aortic aneurysm repair

BACKGROUND

The aim of this study was to evaluate the feasibility and utility of intraoperative contrast-enhanced ultrasound (CEUS) for early detection of endoleaks (ELs) during endovascular abdominal aortic aneurysm repair (EVAR) compared with completion digital subtraction angiography.

METHODS

Patients undergoing elective EVAR from January 2017 to April 2018 were consecutively enrolled in this prospective study. After endograft deployment, two-digital subtraction angiography (2DSA) with orthogonal C-arm angulations (anteroposterior and sagittal view) were routinely performed. After the endovascular treatment of clear, high-flow type I/III ELs detected by 2DSA, intraoperative CEUS was carried out in sterile conditions on the surgical field before guidewire removal. Presence and type of EL were evaluated with 2DSA and CEUS. CEUS was performed with the vascular surgeon blinded to the 2DSA findings. The primary end point was the level of agreement between 2DSA and CEUS to detect any type of EL and type II EL. Agreement between two diagnostic methods was calculated using Cohen's kappa. The secondary end point was utility of CEUS for intraoperative adjunctive procedure guidance.

RESULTS

Sixty patients were enrolled (mean age, 78 ± 6 years; 90% male). 2DSA revealed 11 ELs (18%; 1 type IA, 10 type II), and CEUS 25 ELs (42%; 2 type IA, 23 type II). 2DSA and CEUS were in agreement in 39 cases (65%; 32 no ELs, 7 type II ELs). CEUS detected 17 ELs not identified by 2DSA (28%; 2 type IA, 15 type II); 2DSA detected three ELs not identified by CEUS (5%; 3 type II). In one case, 2DSA and CEUS detected type II and type IA ELs, respectively. For EL and type II EL detection, Cohen's kappa was 0.255 and 0.250, respectively (both "fair agreement"). Intraoperative adjunctive sac embolization was performed under CEUS control in 4 cases and technical success was 100%.

CONCLUSIONS

Intraoperative CEUS during EVAR is feasible and can detect a greater number of ELs than 2DSA, in particular type II ELs. Further studies are necessary to assess the reliability of this intraoperative diagnostic examination. In type II ELs, CEUS may represent an additional, useful tool for intraoperative sac embolization guidance.

A Narrative Review on Contrast-Enhanced Ultrasound in Aortic Endograft Endoleak Surveillance

Endovascular repair of abdominal aortic aneurysms have been performed successfully since 1991. However, 20% to 50% of these patients may develop an endoleak or continued aneurysmal sac expansion or perfusion despite stent graft coverage. Current recommendations suggest lifelong surveillance with computed tomographic angiography (CTA) at least 1 month after intervention and yearly after that. In select patients with a stable aneurysm sac on computed tomography performed 1 year after treatment, future screening could be performed with ultrasonography. However, color Doppler ultrasound can fail to detect as many as 31% of endoleaks. Contrast-enhanced ultrasound (CEUS) provides an alternative approach to excluded aneurysm sac follow-up imaging. The Society for Vascular Surgery notes a need for further research on the role of CEUS in endovascular aortic repair surveillance. The European Federation of Societies for Ultrasound in Medicine and Biology suggests that early results are promising. Meta-analyses report pooled sensitivities and specificities of CEUS compared with CTA for the detection of endoleak between 89% and 98% and 86% and 88%, respectively. Owing to the dynamic flow information it provides, CEUS may actually be more sensitive than CTA at detection and characterization in select circumstances. Challenges with adoption, patient selection, and operator dependency remain, but current and future research suggests a role for CEUS in endoleak surveillance.

Multimodality imaging assessment of endoleaks post-endovascular aortic repair

Endoleaks are a common complication of endovascular aortic repair (EVAR). As a result, patients require lifelong imaging surveillance following EVAR. In current clinical practice, evaluation for endoleaks is predominantly performed with CT angiography (CTA). Due to the significant cumulative radiation burden associated with repetitive CTA imaging, as well as the repeated administration of nephrotoxic contrast agent, contrast-enhanced ultrasound (CEUS) and magnetic resonance angiography (MRA) have evolved as potential modalities for lifelong surveillance post-EVAR. In this paper, multimodality imaging, including CTA, CEUS and MRA, for the surveillance of endoleaks is discussed. Further, new CTA techniques for radiation reduction are elaborated. Additionally, imagery for three cases of aortic endoleak detection using CTA and five cases using MRA are presented. Imaging for different types of endoleaks with CTA, MRA and CEUS are presented. For lifelong endoleak surveillance post-EVAR, CTA is still regarded as the imaging modality of choice. However, advancements in CEUS and MRA technique enable partial replacement of CTA in certain 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.

The Assessment of Carbon Dioxide Automated Angiography in Type II Endoleaks Detection: Comparison with Contrast-Enhanced Ultrasound

Introduction

Iodinated contrast media completion angiography (ICM-A) may underestimate the presence of type II endoleak (ELII) after endovascular aortic repair (EVAR), particularly if they are at low flow. Contrast-enhanced ultrasound (CEUS) has been proposed as the gold standard in ELII detection during EVAR follow-up. Intraprocedural carbon dioxide (CO₂) angiography has been shown to be useful in this setting; however no comparative studies including these three techniques are currently available. Our aim was to investigate the accuracy of a new automated CO₂ angiographic (CO₂-A) system in the detection of ELII, by comparing it with ICM-A and CEUS.

Methods

A series of consecutive patients undergoing EVAR for abdominal aortic aneurysm (AAA) were enrolled and submitted to ICM-A and CO₂-A during the procedure. The iodinated contrast media were delivered through an automatic injector connected to a pigtail catheter in the suprarenal aorta. CO₂ was delivered through a recently available automatic injector connected to a 10 F sheath positioned in the external iliac artery. All patients were blindly evaluated by CEUS within postoperative day 1. The ICM-A and CO₂-A ability to detect ELII was compared with that of CEUS through Cohen's concordance Index (K).

Results

Twenty-one patients were enrolled in the study. One (5%), seven (33%), and four (19%) ELII were detected by ICM-A, CO₂-A, and CEUS, respectively. The only ELII detected by ICM-A was also detected by CO₂-A and CEUS. Three cases of ELII detected by CO₂-A were not detected by CEUS. All ELII detected by CEUS were visualized by CO₂-A. CEUS and ICM-A showed a poor agreement (Cohen's K: 0.35) while CEUS and CO₂-A showed a substantial agreement (Cohen's K: 0.65) for ELII detection.

Conclusion

CO₂-A is safe and effective method for ELII detection in EVAR, with a significantly higher agreement with CEUS if compared with ICM-A. This trial is registered with 155/2015/U/Oss.

Vascular ultrasound, the potential of integration of multiparametric ultrasound into routine clinical practice

Introduction

Ultrasound has traditionally been regarded as the first-line imaging modality for screening, diagnostic evaluation and monitoring treatment and disease progression of vascular pathology, including both the arterial and the venous branch of the vascular system. Albeit of its well-tolerated nature, wide availability and low cost, ultrasound above all, has the advantage of providing the clinician with clinically significant information related to both intraluminal irregularities and extravascular disease. Ultrasound has the potential not only to anatomically describe tissues but also to assess physiology by evaluating blood flow characteristics in real time.

Discussion

The already fundamental role of ultrasound has been even more expanded with the introduction of newer techniques like contrast-enhanced ultrasound, tissue-elastography and 3D ultrasound and the incorporation of research advances into clinical practice. The purpose of this review is to present and discuss some of the latest advances in the field of vascular ultrasound in attempt to illustrate how the adoption of multiparametric ultrasound into everyday clinical practice could address the patient's needs. Pathology and applications discussed include carotid and aortic disease, portal and peripheral venous abnormalities.

Conclusion

Widespread availability of modern technology in ultrasound devices has made the application of contrast-enhanced ultrasound, tissue elastography and 3D ultrasound feasible options, ready to contribute to the diagnostic performance of the ultrasonographic technique.

Quantitative Three-Dimensional Dynamic Contrast-Enhanced Ultrasound Imaging: First-In-Human Pilot Study in Patients with Liver Metastases

Purpose: To perform a clinical assessment of quantitative three-dimensional (3D) dynamic contrast-enhanced ultrasound (DCE-US) feasibility and repeatability in patients with liver metastasis, and to evaluate the extent of quantitative perfusion parameter sampling errors in 2D compared to 3D DCE-US imaging.

Materials and Methods: Twenty consecutive 3D DCE-US scans of liver metastases were performed in 11 patients (45% women; mean age, 54.5 years; range, 48-60 years; 55% men; mean age, 57.6 years; range, 47-68 years). Pairs of repeated disruption-replenishment and bolus DCE-US images were acquired to determine repeatability of parameters. Disruption-replenishment was carried out by infusing 0.9 mL of microbubbles (Definity; Latheus Medical Imaging) diluted in 35.1 mL of saline over 8 min. Bolus consisted of intravenous injection of 0.2 mL microbubbles. Volumes-of-interest (VOI) and regions-or-interest (ROI) were segmented by two different readers in images to extract 3D and 2D perfusion parameters, respectively. Disruption-replenishment parameters were: relative blood volume (rBV), relative blood flow (rBF). Bolus parameters included: time-to-peak (TP), peak enhancement (PE), area-under-the-curve (AUC), and mean-transit-time (MTT).

Results: Clinical feasibility and repeatability of 3D DCE-US using both the destruction-replenishment and bolus technique was demonstrated. The repeatability of 3D measurements between pairs of repeated acquisitions was assessed with the concordance correlation coefficient (CCC), and found to be excellent for all parameters (CCC > 0.80), except for the TP (0.74) and MTT (0.30) parameters. The CCC between readers was found to be excellent (CCC > 0.80) for all parameters except for TP (0.71) and MTT (0.52). There was a large Coefficient of Variation (COV) in intra-tumor measurements for 2D parameters (0.18-0.52). Same-tumor measurements made in 3D were significantly different (P = 0.001) than measurements made in 2D; a percent difference of up to 86% was observed between measurements made in 2D compared to 3D in the same tumor.

Conclusions: 3D DCE-US imaging of liver metastases with a matrix array transducer is feasible and repeatable in the clinic. Results support 3D instead of 2D DCE US imaging to minimize sampling errors due to tumor heterogeneity.

Planning, Execution, and Follow-up for Endovascular Aortic Aneurysm Repair Using a Highly Restrictive Iodinated Contrast Protocol in Patients with Severe Renal Disease

BACKGROUND

The cumulative amount of iodinated contrast medium necessary for endovascular repair (EVAR) planning, operative procedure, and subsequent follow-up is a threat for the onset of end-stage renal disease in patients with preoperative impaired kidney function. The purpose of this study was to describe a mini-invasive approach aimed to minimize the exposure of these patients to iodinated contrast medium and the subsequent risk of renal function worsening.

METHODS

From 2012 to 2015, all patients with abdominal aortic aneurysm (AAA) at high surgical risk and fit for standard EVAR (simple aortic-iliac anatomy: proximal and distal neck length ≥15 mm, no severe angulation), underwent EVAR through the following "near-zero contrast" approach, if their glomerular filtration rate (GFR) was <30 mL/min: preoperative planning was performed by noncontrast-enhanced computed tomography and duplex ultrasound (DU); the origin of renal/hypogastric arteries and aortic bifurcation was evaluated and matched with vertebral bone landmarks and the endograft deployed accordingly, using <20 cc of isotonic iodinate contrast medium and contrast-enhancement DU (CEUS). Follow-up was by DU/CEUS at 1, 6, and 12 months. Primary end points were technical success (TS: renal/hypogastric artery patency, absence of type I/III endoleaks, iliac stenosis/kinking, intraoperative mortality, and conversion), 30-day mortality, and new onset of permanent dialysis with renal function evaluation at 1, 6, and 12 months. Secondary end points were type II endoleaks, reinterventions, AAA, and renal-related mortality during the follow-up.

RESULTS

Eighteen patients (median age: 74 years, interquartile range [IQR]: 6, male: 78%, American Society of Anaesthesiologists [ASA] IV: 100%) were enrolled. The median AAA diameter and preoperative GFR were 66 mm (IQR: 13) and 22 mL/min (IQR: 4), respectively. Infrarenal (n = 10) and suprarenal fixation (n = 8) endografts were implanted, with a mean dose of iodinate contrast medium injection of 18 mL (IQR) and 100% TS rate. Two type II endoleaks were detected at the completion CEUS. The median postoperative GFR was 22 mL/min (IQR: 5). No patients had GFR worsening ≥30% at 1 day and 30 days. The 30-day mortality was 11% (2 deaths for heart failure). At a median follow-up of 16 months (IQR: 8), no patients needed hemodialytic treatment and no endoleaks were detected. One patient died at 6 months for cancer and one at 13 months for myocardial infarction. No reinterventions or AAA and renal-related mortality occurred during the follow-up.

CONCLUSIONS

A "near-zero contrast" approach is feasible in EVAR for patients with simple aorto-iliac anatomy. Patients with very poor renal function may still undergo to successful procedures, avoiding renal function impairment.

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.

Standardized 2D ultrasound versus 3D/4D ultrasound and image fusion for measurement of aortic aneurysm diameter in follow-up after EVAR

PURPOSE

To compare standardised 2D ultrasound (US) to the novel ultrasonographic imaging techniques 3D/4D US and image fusion (combined real-time display of B mode and CT scan) for routine measurement of aortic diameter in follow-up after endovascular aortic aneurysm repair (EVAR).

METHOD AND MATERIALS

300 measurements were performed on 20 patients after EVAR by one experienced sonographer (3rd degree of the German society of ultrasound (DEGUM)) with a high-end ultrasound machine and a convex probe (1-5 MHz). An internally standardized scanning protocol of the aortic aneurysm diameter in B mode used a so called leading-edge method. In summary, five different US methods (2D, 3D free-hand, magnetic field tracked 3D - Curefab™, 4D volume sweep, image fusion), each including contrast-enhanced ultrasound (CEUS), were used for measurement of the maximum aortic aneurysm diameter. Standardized 2D sonography was the defined reference standard for statistical analysis. CEUS was used for endoleak detection.

RESULTS

Technical success was 100%. In augmented transverse imaging the mean aortic anteroposterior (AP) diameter was 4.0±1.3 cm for 2D US, 4.0±1.2 cm for 3D Curefab™, and 3.9±1.3 cm for 4D US and 4.0±1.2 for image fusion. The mean differences were below 1 mm (0.2-0.9 mm). Concerning estimation of aneurysm growth, agreement was found between 2D, 3D and 4D US in 19 of the 20 patients (95%). Definitive decision could always be made by image fusion. CEUS was combined with all methods and detected two out of the 20 patients (10%) with an endoleak type II. In one case, endoleak feeding arteries remained unclear with 2D CEUS but could be clearly localized by 3D CEUS and image fusion.

CONCLUSION

Standardized 2D US allows adequate routine follow-up of maximum aortic aneurysm diameter after EVAR. Image Fusion enables a definitive statement about aneurysm growth without the need for new CT imaging by combining the postoperative CT scan with real-time B mode in a dual image display. 3D/4D CEUS and image fusion can improve endoleak characterization in selected cases but are not mandatory for routine practice.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Contemporary Applications of Ultrasound in Abdominal Aortic Aneurysm Management

Ultrasound (US) is a well-established screening tool for detection of abdominal aortic aneurysms (AAAs) and is currently recommended not only for those with a relevant family history but also for all men and high-risk women older than 65 years of age. The advent of minimally invasive endovascular techniques in the treatment of AAAs [endovascular aneurysm repair (EVAR)] has increased the need for repeat imaging, especially in the postoperative period. Nevertheless, preoperative planning, intraoperative execution, and postoperative surveillance all mandate accurate imaging. While computed tomographic angiography and angiography have dominated the field, repeatedly exposing patients to the deleterious effects of cumulative radiation and intravenous nephrotoxic contrast, US technology has significantly evolved over the past decade. In addition to standard color duplex US, 2D, 3D, or 4D contrast-enhanced US modalities are revolutionizing AAA management and postoperative surveillance. This technology can accurately measure AAA diameter and volume, and most importantly, it can detect endoleaks post-EVAR with high sensitivity and specificity. 4D contrast-enhanced US can even provide hemodynamic information about the branch vessels following fenestrated EVARs. The need for experienced US operators and accredited vascular labs is mandatory to guarantee the reliability of the results. This review article presents a comprehensive overview of the literature on the state-of-art US imaging in AAA management, including post-EVAR follow-up, techniques, and diagnostic accuracy.

Contrast-Enhanced Sonographic Follow-up After Stenting of Visceral Artery Aneurysms

We report 2 cases of exclusion of visceral artery aneurysms. The first was a common hepatic artery aneurysm treated with a multilayer stent; the second was a celiac trunk aneurysm excluded by a covered stent. Computed tomographic angiography was performed at regular intervals after each procedure, together with echo color Doppler imaging and contrast-enhanced sonography. Computed tomographic angiography and contrast-enhanced sonography were able to detect endoleaks in both patients and the related inflow vessel; moreover, diameter measurements of the sacs were identical. In our preliminary experience, contrast-enhanced sonography appeared to be as accurate as computed tomographic angiography after endovascular visceral artery aneurysm exclusion.

Contrast echocardiography: latest developments and clinical utility

Ultrasound enhancing agents (UEAs) are being utilized for a growing number of applications with real-time very low mechanical index (MI) techniques in clinical cardiology today. This article will review recent developments on the safety of UEAs and their effectiveness in myocardial perfusion imaging, three-dimensional quantification of left ventricular function, and vascular imaging. UEAs are now being utilized in all age groups, with new indications that add incremental value to the currently approved by the Food and Drug Administration. These include the incremental value in cardiac imaging, where the off-label analysis of myocardial perfusion observed with UEAs adds to the enhanced endocardial border delineation. In carotid artery imaging, UEAs improve the detection of plaque but also can examine plaque neovascularization. Vascular surgeons now utilize UEAs in the evaluation of endovascular repair to detect endoleaks without the need of ionizing radiation. Newer applications are emerging in the detection of left atrial appendage thrombi and quantification of myocardial blood flow and volume in transplant patients.