Clinical and technical evidence
A literature search was carried out for this briefing in accordance with the interim process and methods statement. This briefing includes the most relevant or best available published evidence relating to the clinical effectiveness of the technology. Further information about how the evidence for this briefing was selected is available on request by contacting firstname.lastname@example.org.
There are 2 studies summarised in this briefing, including 120 patients.
A number of studies have been published on similar devices that use tomographic ultrasound for abdominal aortic aneurysm (AAA) surveillance and endovascular aneurysm repair (EVAR) endoleak detection.
The evidence base for PIUR tUS is limited, comprising of 1 proof-of-principle study and 1 prospective study. Both studies consider the technology for endoleak detection after EVAR and were done in the NHS. There is no published evidence on the technology for AAA detection.
Rotational angiography, contrast-enhanced ultrasound (CEUS) and contrast-enhanced tomographic 3D ultrasound (CEtUS, PIUR tUS) immediately after surgery.
Presence of endoleak (10 endoleaks found by CEUS and CEtUS, 4 detected by rotational angiography. Type IIb endoleaks were not detected by rotational angiography). The authors note that CEUS and CEtUS did not produce an image that could be used for diagnosis in 1 patient because of a body mass index of 40.4 and extensive bowel gas. The imaging technique was uncertain (type of endoleak could not be determined) in another 2 patients, but no reason for the failure is provided. Rotational angiography did not detect any type IIb endoleaks, 7 and 8 type IIb endoleaks were detected by CEUS and CEtUS, respectively.
Renal artery patency was found in 27 and 26 renal arteries, respectively. Rotational angiography found 39 patent renal arteries.
The authors noted that it would be useful to have CEUS or CEtUS as an option for endoleak detection immediately after EVAR for patients in whom contrast agents should be minimised. They also noted that less clinician skill and time are needed for a diagnostically acceptable image using CEtUS compared with CEUS and rotational angiography. One of the authors is a founder of the company.
Computed tomography angiography (CTA), CEUS and 3D-CEUS (prototype PIUR tUS) immediately after surgery. CTA, CEUS and 3D-CEUS were done on the same day and 3D-CEUS was reported independently by 2 blinded vascular scientists.
Using CTA as a gold standard, 3D-CEUS detected endoleaks with 96% sensitivity, 91% specificity, 90% positive predictive value and 96% negative predictive value. The κ statistic for interoperator agreement was 0.89.
The authors noted that that the study reached statistical power to show diagnostic accuracy when 67 comparisons (total 100) were made. CTA, CEUS and 3D-CEUS were done on the same day in 52 patients, the rest were done within 4 weeks. The authors noted that they do not expect this to have affected results.
One of the authors is a founder of the company. However, this study used a prototype device and was funded by the Wellcome Trust and Manchester Surgical Research Trust. This meant no conflicts of interest were declared at publication.
This technology may reduce the need for CT scans. This could reduce environmental impact, but there is no evidence to support this.