Laser Doppler flux-metry in laryngeal squamous cell carcinoma

Motion Tracking System for Robust Non-Contact Blood Perfusion Sensor

We propose a motion-robust laser Doppler flowmetry (LDF) system that can be used as a non-contact blood perfusion sensor for medical diagnosis. Endoscopic LDF systems are typically limited in their usefulness in clinical contexts by the need for the natural organs to be immobilized, as serious motion artifacts due to the axial surface displacement can interfere with blood perfusion measurements. In our system, the focusing lens moves to track the motion of the target using a low-frequency reference signal in the optical data, enabling the suppression of these motion artifacts in the axial direction. This paper reports feasibility tests on a prototype of this system using a microfluidic phantom as a measurement target moving in the direction of the optical axis. The frequency spectra detected and the perfusion values calculated from those spectra show that the motion tracking system is capable of suppressing motion artifacts in perfusion readings. We compared the prototype LDF system’s measurements with and without motion feedback, and found that motion tracking improves the fidelity of the perfusion signal by as much as 87%.

Validation of laser Doppler fluxmetry as a method of assessing neo-angiogenesis in laryngeal tumours

Our intention was to validate the hypothesis that laser Doppler fluxmetry would give a valid representation of underlying tissue blood flow and would provide a reliable tool for measuring blood flow in human laryngeal cancers. This was an experimental prospective study. We performed laser Doppler fluxmetry on 20 patients with laryngeal cancer and compared the values obtained through this method with manual counting of microvessel density from biopsies, the accepted gold standard. We demonstrated good inter- and intraobserver variability in our estimation of microvessel density. We then compared microvessel density with laser Doppler fluxmetry, and using Spearman's test to assess nonparametric correlation, we obtained a correlation coefficient of 0.4 (P value: 0.15). To our knowledge, this study is the first of its kind to demonstrate a positive trend between angiogenesis measured conventionally when compared with laser Doppler fluxmetry.