Blood vessel detection in medical procedures using laser Doppler flowmetry

The needle procedures such as coronary angioplasty and coronary artery bypass graft installation are the most common surgical interventions performed in medical practice, and the accuracy of the catheter needle placement defines the success of the whole operation. Due to anatomical variations in patients, finding and puncturing the correct blood vessel is a challenging step, and the needle guidance might significantly simplify the process. Therefore, the primary aim of this work was to develop a novel blood vessel detection system based on laser Doppler flowmetry (LDF) technology that will improve the quality of medical needle procedures. In this work, LDF measurement setup was designed, assembled and evaluated.
The setup includes custom laser-detector system, two invasive measurements probes, two experimental phantoms and data acquisition software. The optical properties of human tissue and blood were examined in order to define the required laser characteristics and relevant tissue-mimicking materials. The data processing was based on the power spectrum analysis, from which the perfusion parameter was extracted. The measurement range of the system was assessed in respect to the various criteria such as penetration angle, depth and site. The applicability of LDF in the needle procedures was evaluated.
The experimental results demonstrated that the blood vessel can be successfully detected in the wide angles range and at different penetration sites. The differentiation between low and high blood flow speeds is also possible. Moreover, the potential of the measurements in tissue was demonstrated. However, certain limitations need to be addressed. It was discovered, that the distiction between the arteria and the vein is challenging, and the penetration depth inside the tissue is restricted. Nevertheless, the proposed technology can be implemented in the needle procedures and a number of other medical applications, such as laparoscopic surgeries and biopsies.