Comparison between multi-channel LDV and PWI for measurement of pulse wave velocity in distensible tubes: Towards a new diagnostic technique for detection of arteriosclerosis

- A custom-built 4-channel vibrometer system for arterial stiffness detection is proposed.
- The 4-channel system is compared with an established technique for arterial stiffness detection, namely pulse wave imaging (PWI), in phantoms.
- Both techniques come to similar results in phantoms.

The aim of this work, was to compare pulse wave velocity (PWV) measurements using Laser Doppler vibrometry (LDV) and the more established ultrasound-based pulse wave imaging (PWI) in smooth vessels. Additionally, it was tested whether changes in phantom structure can be detected using LDV in vessels containing a local hardening of the vessel wall.Results from both methods showed good agreement illustrated by the non-parametric Spearman correlation analysis (Spearman-ρ = 1 and p< 0.05) and the Bland-Altman analysis (mean bias of −0.63 m/s and limits of agreement between −0.35 and −0.90 m/s).The PWV in soft phantoms as measured with LDV was 1.30±0.40 m/s and the PWV in stiff phantoms was 3.6±1.4 m/s. The PWV values in phantoms with inclusions were in between those of soft and stiff phantoms.However, using LDV, given the low number of measurement beams, the exact locations of inclusions could not be determined, and the PWV in the inclusions could not be measured. In conclusion, this study indicates that the PWV as measured with PWI is in good agreement with the PWV measured with LDV although the latter technique has lower spatial resolution, fewer markers and larger distances between beams. In further studies, more LDV beams will be used to allow detection of local changes in arterial wall dynamics due to e.g. small inclusions or local hardenings of the vessel wall.