Accuracy, Descending Aortic Aneurysm, Feasibility, Reproducibility, Ultrasound
Conditions
Brief summary
The goal of this observational study is to assess the applicability of non-invasive ultrasound in aneurysms of the descending thoracic aorta. The main question it aims to answer is: What is the feasibility of Ultrasound to visualise the Descending Thoracic Aorta, and can this imaging modality accurately measure the maximum size of aneurysms and residual sacs with acceptable reproducibility? Participants are having their diagnosis confirmed or excluded by conventional imaging techniques (CT scans). Participants receive exactly the same standard of care regardless of their participation. The study offers an additional ultrasound scan, and the results will be compared with previous imaging.
Detailed description
Aneurysms of the aortic artery are a significant public health issue. The number of newly diagnosed aneurysms of the thoracic aorta is on the rise, and aneurysm rupture is a catastrophic event associated with high mortality rates. The most proximal sections of the aorta (ascending and the aortic arch) are routinely scanned by echocardiography practitioners. The abdominal aorta is also easily visualised on transabdominal ultrasound, and there is a screening programme in the UK that is highly cost-effective and reduced the aneurysm-related number of deaths. However, the portion of the aorta in the chest (descending thoracic aorta) is not routinely assessed by ultrasound practitioners. The diagnosis of descending thoracic aneurysms relies mostly on imaging techniques that use ionising radiation. In addition, these techniques are expensive and may not be widely available in some regions. In contrast, ultrasound is a non-invasive technique that allows visualisation of most parts of the body. Ultrasound machine suppliers have invested in better systems and transducers over the years and visualisation of the descending thoracic aorta may now be possible. The main aims of this study are to assess the feasibility (Part 1), accuracy (Part 2) and reproducibility (Part 3) ultrasound in the diagnosis and monitoring of descending thoracic aortic aneurysms. Participants will be recruited from the vascular lab and outpatient clinics, and diameters of the descending thoracic aorta will be measured with non-invasive ultrasound. Data obtained from study measurements will be compared with computed tomography scans that patients had as part of their standard of care. If the feasibility, accuracy and reproducibility of Ultrasound are clearly demonstrated, routine ultrasound scans of the descending thoracic aorta may be suggested.
Interventions
None listed
Sponsors
Imperial College London
Study design
Observational model
COHORT
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
* Patients with diagnosed AAA or other vascular condition attending the vascular scanning department for routine ultrasound and confirmed healthy DTA (Control group). * Patients with known DTAA (including Type B dissection) or patients who had TEVAR previously (Case group). * Patients who have had CT as part of their standard of care. * Patients able to tolerate the scan (Lying in supine position). * Adults aged 18 or over. * Willing to provide consent.
Exclusion criteria
* Patient under 18 years of age. * Previous thoracic surgery or body deformity (severe kyphosis, scoliosis, pleural effusion or chest wall trauma). * Patients without previous imaging of the thoracic aorta. * Life expectancy \<2 years. * Pregnant Women. * Patients unwilling to provide consent or unable to comply with study requirements. * Patients too frail to travel to routine outpatient appointments. * Inability to attend the appointment due to time constraints or other commitments. * Although rare, ultrasound contraindications as described in the scanning protocol are also
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Part 1 - Feasibility - Proportion of participants with successful ultrasound measurement of the diameter of the descending thoracic aorta | Day 1 - At the single ultrasound study visit. | Number and percentage of participants in whom the descending thoracic aortic diameter can be obtained by transthoracic ultrasound. The units of Measure are total number and percentages. |
| Part 1 - Feasibility - Length of the descending thoracic aorta by Ultrasound | Day 1 - At the single ultrasound study visit. | Total length of the descending thoracic aorta from the aortic isthmus to the coeliac axis. The unit of Measure is Centimetres (cms). |
| Part 1 - Feasibility - Ultrasound Quality Score | Day 1 - At the single ultrasound study visit. | Number of ultrasound windows that allow visualisation of the descending thoracic aorta (0 to 3 windows) and allocation of a quality score. The Unit of Measure is a score created for this study (0-Windows: No views; 1 window: Poor; 2 windows: Moderate; 3 windows: Good). Higher scores mean better image quality. |
| Part 2 - Accuracy - Comparision between Transthoracic Ultrasound and CT | Day 1 - At the single ultrasound study visit. | Calculate mean differences and limits of agreement between TUS and CT. Achieve high sensitivity and specificity. |
| Part 3 - Reproducibility - Intraclass correlation coefficient | Day 1 - At the single ultrasound study visit. | Calculate inter- and intra-operator variability by intraclass correlation coefficient (ICC). The study aims to achieve good or excellent reliability. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Part 1 - Feasibility - Factors limiting visualisation of the Descending Thoracic Aorta | Day 1 - At the single ultrasound study visit. | Number and percentages of participants in whom limiting factors such as body habitus or rib shadowing are reported after the ultrasound test. The units of measure are the number of participants with raised BMI (kg/m\^2) and acoustic shadowing due to bone density. |
| Part 1 - Feasibility - Duration of Ultrasound Examination | Day 1 - At the single ultrasound study visit. | Total time needed to complete the ultrasound scan of the descending thoracic aorta. The unit of measure is minutes. |
| Part 1 - Feasibility - Patient Feedback Questionnaire | Day 1 - At the single ultrasound study visit. | Scores are obtained from the patient feedback questionnaire that was created specifically for this study and consists of 5 questions relating to comfort, tolerability and overall experience of the ultrasound scan. The unit of measure is a score ranging from 1-Strongly Disagree to 5-Strongly Agree. Higher scores mean better patient satisfaction. |
Countries
United Kingdom
Contacts
CONTACTCarlos Pinho, PhD Student
CONTACTCheuk Fund Wong
STUDY_CHAIRProfessor Colin Bicknell
Imperial College London
Outcome results
None listed