Optical incoherent technique for noninvasive assessment of blood flow in tissues: Theoretical model and experimental study

Abstract

Laser noninvasive methods for assessment of a tissue blood flow (BF), for example, the Laser Doppler Flowmetry (LDF), are well-known today. However, in such methods, low-frequency fluctuations (LFFs) in the registered optical signal caused by blood volume changes inside a tissue have not been studied in details until now. The aim of this study is to investigate the LFFs formation and to justify the LFFs-based diagnostic technique for cutaneous BF assessment. LFFs are theoretically described and experimentally shown in the input LDF signal inside the frequency range 0 to 10 Hz. They are substantiated as the basis of the new diagnostic method, in which BF is defined as the magnitude of blood volume changes in a tissue per unit time. The hand-made prototype of the promising diagnostic tool with light emitted diodes is used to validate the technique in experiments in vivo on 16 healthy volunteers in comparison with the LDF method. Experimental results show a good similarity of the recorded BF for both coherent and incoherent method. The proposed technique makes it possible the creation of inexpensive diagnostic equipment for assessment of cutaneous BF without using lasers and coherent light, completely and functionally comparable to LDF devices.

Incoherent Optical Fluctuation Flowmetry: A New Method for the Assessment of Foot Perfusion in Patients with Diabetes-Related Lower-Extremity Complications

“…In addition, because of the probe design, the signal is analyzed from a larger area of skin (~25 mm 2 ). Due to this, the signal backscattered from the tissue is collected from a larger tissue volume than in LDF and includes deeper vascular plexuses and larger vessels [ 14 , 15 ]. This also reduces the impact of local vascular network heterogeneity on measurement variability.…”

“…The prototype device uses three LED emission sources operating in the wavelength range of 560–580 nm and one silicon photodiode in the optical sensor. The perfusion value calculated during signal processing is similar to that in laser Doppler flowmetry (LDF) [ 15 , 19 ]. The method allows the assessment of perfusion measured in perfusion units (PU).…”

“…An incoherent optical fluctuation flowmetry (IOFF) method has been developed in the Laboratory of Medical and Physical Research, Moscow Regional Research and Clinical Institute (“MONIKI”) [ 15 ]. This is the first study to assess the clinical perspectives of the method in healthcare.…”

Skin microcirculation reactivity to local thermal hyperaemia in patients with COVID-19 — A pilot observational study

“…Examples of methods allowing non-invasive assessment of skin microcirculation include laser Doppler flowmetry (LDF), laser speckle-contrast imaging (LSCI), novel method of incoherent optical fluctuation flowmetry (IOFF), capillaroscopy, etc. [9][10][11][12][13].…”

Novel Method to Assess Endothelial Function via Monitoring of Perfusion Response to Local Heating by Imaging Photoplethysmography

“…It is worth noting that despite almost half a century of history of using the LDF method in microcirculation research, it is still not used in clinical practice. Recently, Lapitan and Rogatkin suggested that the reason for LDF drawbacks is more fundamental and related to the nature of coherent light used in this technique [ 27 ]. To improve the performance of an optical technique in a blood flow assessment, they proposed the use of incoherent light, as is commonly used in the photoplethysmography (PPG) method.…”