Value of ultrasound machine settings optimisation for better diagnosis of superficial femoral artery atherosclerosis

Abstract

Background and Purpose: Atherosclerosis in the superficial femoral artery can be imaged using various imaging modalities. Although catheter based angiography is considered to be the gold standard, it is only indicated in cases of planned intervention. CTA and MRA have become the preferred modalities for assessing the vascular system, however ultrasound is providing a new in-sight in the field. Customisation of several scan parameters in ultrasound is essential to obtain consistent and reliable results. The purpose of this study is to help the reader understand the importance of ultrasound physics, and decide on how best to set these scan parameters, and their effect on the resultant images for the particular clinical task. Aims and Objectives: This study evaluates and quantifies the difference in image quality between two vascular ultrasound protocols. One protocol is based on the default factory pre-set without further scan parameter adjustments along the scan, while the second protocol dictates the adjustment, based on physics principles, of various scan parameters along the scan. Methodology: This study recruited a random sample of 60 patients out of a possible 750, which included patients with a wide range of body types and disease severity. The images obtained by the two protocols where evaluated against a list of 16 quality criteria, covering; Anatomy, Detection of disease, Classification of disease, Extent of disease, Severity of disease, Consistency of results and Referral to further imaging. Results and Conclusions: The images obtained by the optimised protocol proved to be better at visualising atherosclerosis in the SFA irrespective of quality criteria, quality class, scanning mode and section of artery scanned. This study concluded that the introduction of a mandatory written scan parameter optimisation protocol would be beneficial and suggests mandatory training and education for ultrasound unit operators performing vascular ultrasound procedures of the superficial femoral artery.