Contrast Enhanced Ultrasound, Endoleak Detection Following EVAR v1.3

Study Overview
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Brief Summary
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A single site cross-sectional comparison of paired diagnostic imaging modalities. This study will show the sensitivity and specificity of CEUS in detecting the various types of endoleaks, in comparison to tCTA, following EVAR. It will collect data to allow comparison of diagnostic accuracy across modalities including CDU, CEUS and tCTA. It will collect time taken to perform the various types of scan, to allow healthcare costs to be calculated for each imaging modality.

Detailed Description
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This study will show the sensitivity and specificity of CEUS in detecting the various types of endoleaks, in comparison to tCTA, following EVAR. It will collect data to allow comparison of diagnostic accuracy across modalities including CDU, CEUS and tCTA. It will collect time taken to perform the various types of scan, to allow healthcare costs to be calculated for each imaging modality. Collected data will be analysed regarding two novel hypothesised methods of using CEUS information: The first is recording temporal delay between contrast in graft and contrast in endoleak to define endoleak type. Potentially this could be used as a faster method of defining endoleak type in a surveillance programme. The second is to identify/refute correlation between CEUS contrast to appear in endoleak vs tCTA contrast to appear in endoleak. If an association can be established, CEUS timings could potentially then be used to time 'standard' CTA phases to improve CTAs diagnostic accuracy.

Official Title
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Contrast Enhanced Ultrasound Endoleak Detection Compared To Time-Resolved Computer Tomography Angiography in High Risk Endovascular Aneurysm Repair (EVAR) Surveillance Patients.

Conditions
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Endoleak, Abdominal Aortic Aneurysm

Intervention / Treatment
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* Radiation: time-resolved CT Angiography
* Procedure: Contrast Enhanced Ultrasound


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Aged 18 or over Able to give informed consent Undergone an EVAR of infra-renal abdominal aortic aneurysm Planned for CTA of EVAR Exclusion Criteria: Unable to receive CTA Contrast Allergy, Insufficient renal function for standard outpatient contrast study (eGFR <45) Overactive thyroid gland Unable to receive CEUS contrast Previous reaction to Sonovue (Ultrasound Contrast) Allergy to sulphur hexafluoride (used in electrical industry in circuit breakers, switch gears & electrical equipment) Recent acute coronary syndrome or unstable angina, typical angina at rest or frequent or repeated angina/chest pain - all within previous 7 days Recent coronary intervention Previous embolization of artery in region of EVAR (affects imaging quality) BMI >30 (affects imaging quality)

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Intervention/Treatment |
| --- |
|Radiation: time-resolved CT Angiography|A multi-phase contrast CT|
|Procedure: Contrast Enhanced Ultrasound|A ultrasound scan with micro bubble contrast injection|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Ability to detect type I/III endoleak on CEUS as defined by presence/absence on tCTA | Will be presented as a Sensitivity & specificity | Immediate | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Ability to detect type II endoleak on CEUS as defined by presence/absence on tCTA | Will be presented as a Sensitivity & specificity | Immediate | 
| Ability to predict secondary intervention on CEUS as defined by patients proceeding to secondary intervention | Will be presented as a Sensitivity & specificity | Immediate | 
| Confirm / refute association between temporal delay measured on CEUS and endoleak type as defined by tCTA, using the framework of general linear regression. | Temporal delay is the time difference between contrast arriving in the stent graft and contrast arriving in the endoleak on CEUS | Immediate | 
| Establish association between CEUS contrast in endoleak to tCTA contrast in endoleak by general linear regression analysis of timings recorded during CEUS & tCTA. |  | Immediate | 
| Ability to predict secondary intervention of CDU, CEUS and tCTAas defined by patients proceeding to secondary intervention | Will be presented as a Sensitivity & specificity | 6 months | 
| Time taken for CDU, CEUS & tCTA scans to be performed as measured by observer. | Used to calculate total resource utilisation by individual scan types. | Immediate |