Prospective, single UK centre, comparative study of the predictive values of contrast-enhanced ultrasound compared to time-resolved CT angiography in the detection and characterisation of endoleaks in high-risk patients undergoing endovascular aneurysm repair surveillance: a protocol

Contrast-Enhanced Ultrasound after Endovascular Aortic Repair: Supplement and Potential Substitute for CT in Early- and Long-Term Follow-Up

BACKGROUND

Endoleaks are the most common complication after endovascular aneurysm repair (EVAR). Computed tomography angiography (CTA) is presently the golden standard for lifelong surveillance after EVAR. Several studies and meta-analyses have shown contrast-enhanced ultrasound (CEUS) to be a good alternative. The main goal of our study was to further validate the inclusion of CEUS in follow-up examination protocols for the systematic surveillance after EVAR.

METHODS

A retrospective analysis of patients who had received CEUS as part of their routine surveillance after EVAR at our center was conducted. Detection rate and classification of endoleak types were compared between available postinterventional CTA/magnetic resonance angiography and follow-up CEUS examinations. Last preinterventional CTAs before EVAR served as baselines with focus on potential cofactors such as age, body mass index, maximum aortic aneurysm diameters, endoleak orientation, and distance-to-surface influencing detection rates and classification.

RESULTS

In total, 101 patients were included in the analysis. Forty-four endoleaks (43.5% of cases) were detected by either initial CEUS or CTA, mostly type II (37.6% of the included patients). Initial CEUS showed an endoleak sensitivity of 91.2%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 84.6%. No covariate with an influence on the correct classification could be identified either for CEUS or CT.

CONCLUSIONS

CEUS should be considered a valid complementary method to CTA in the lifelong surveillance after EVAR. As type II endoleaks seem to be a common early-term, sometimes spontaneously resolving complication that can potentially be missed by CTA, we suggest combined follow-up protocols including CEUS in the early on postinterventional assessment.

Type II endoleak accompanied by an arteriovenous fistula between the inferior mesenteric artery and the inferior vena cava as a complication of endovascular aneurysm repair

Endovascular aneurysm repair (EVAR) has become one of the most important treatments for aortic abdominal aneurysm. This method has some possible complications, including a type II endoleak (T2E). When coexisting with arteriovenous fistulas (AVF), T2E can lead to serious hemodynamic consequences and organ failure. This report describes the management of a patient with T2E coexisting with AVF following an EVAR and re-EVAR procedure. Although T2E itself may be treated with a conservative approach in some cases, in the presented patient an operative approach was necessary because of coexisting AVF. In addition, due to unusual hemodynamic conditions created by concomitant ACF and T2E, fistula closure was obtained as a result of transarterial inferior mesenteric artery embolization. Post-EVAR imaging, including ultrasound and computed tomography angiography, has proven to be essential when caring for these patients.

Dynamic, Time-Resolved Computed Tomography Angiography Technique to Characterize Aortic Endoleak Type, Inflow and Provide Guidance for Targeted Treatment

PURPOSE

To illustrate dynamic, time-resolved CTA (d-CTA) imaging technique in characterizing aortic endoleak type/inflow using quantitative parameters and its value in providing image guidance for targeted treatment approach.

TECHNIQUE

Dedicated endoleak protocol involved acquiring multiple time-resolved contrast enhanced scans using third-generation CT scanner (Somatom Force^®, Siemens Healthineers). Parameters such as scan field of view (FOV), kV, number/timing of scans were customized based on patient's body-mass-index, timing bolus, and prior imaging findings. D-CTA image datasets were evaluated qualitatively and quantitatively using time-attenuation curves (TAC) analysis after motion correction using a dedicated software (syngo.via^®, Siemens). D-CTA findings from 4 illustrative cases demonstrating type I, type II (inferior mesenteric and lumbar artery inflow), and type III endoleak were illustrated. TAC analysis with time to peak parameter enabled better characterization of endoleak type and inflow. During endoleak intervention, target vessels from d-CTA images were electronically annotated and overlaid on fluoroscopy using 2D-3D image fusion to provide image guidance for targeted treatment.

CONCLUSION

D-CTA imaging with TAC analysis characterizes aortic endoleak type and inflow, in addition to providing image guidance for targeted endoleak treatment. Such dynamic, time-resolved imaging techniques may provide further insights into understanding aortic endoleak that remains an Achilles heel for endovascular aortic aneurysm repair.