Optical techniques to quantitatively assess changes in blood supply during surgery

Abstract

In modern surgery, intraoperative assessment of blood perfusion is an urgent but still unresolved problem. Due to the fact that light has minimal impact on biological tissue, optical methods are the most promising for non-contact measurements of blood flow in-vivo. Various methods such as indocyanine green light fluorescence angiography, laser Doppler flowmetry, imaging photoplethysmography (IPPG), laser speckle contrast imaging, hyperspectral imaging, and optical coherence tomography are actively being investigated as candidates for contactless intraoperative measurement of tissue perfusion. Despite the long-term study of these methods, the basic fundamental question of the interaction of light with living biological tissue containing blood vessels remains insufficiently comprehended. For example, the reasons why light, after its interaction with tissue, is modulated at the heart rate are still a matter of debate. In this lecture, I will present a number of experimental observations that cannot be explained within the framework of the generally accepted model. The question of how the observed modulation of light is related to the parameters of blood flow and its changes during surgical interventions will be discussed. Special attention will be paid to discussing the progress in the development of the multimodal IPPG +ECG system, which allows for high-resolution intraoperative assessment of perfusion in both space and time. The results of the latest pilot studies on monitoring neurosurgical and abdominal operations using IPPG system in a clinical setting will be presented. The work is supported by the Russian Science Foundation (grant No. 25-15-00400).

Speaker

Alexei A. Kamshilin
Institute of Automation and Control Processes FEB RAS
Russia

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