Optical Spectroscopy of Cerebral Blood Flow for Tissue Interrogation in Ischemic Stroke Diagnosis

Ischemic stroke remains a leading cause of morbidity and mortality worldwide, and early diagnosis is critical for improving clinical outcomes. This paper presents an optical design framework combining speckle contrast optical spectroscopy (SCOS) with multiwavelength reflectance spectroscopy to monitor subtle changes in cerebral blood flow during ischemic events. The research aims to enable precise tissue interrogation using high-resolution, low-scatter imaging. Key to the system's accuracy is a 1.55 μm small beam waist, a grating density of 1300 grooves/mm, and a 15.53 μm depth of focus. The calculated effective focal length of 8333.33 μm enhances the resolution to 4.07 μm, improving the detection of minor changes in tissue optical properties. We investigate the sensitivity of various near-infrared wavelengths (660, 785, 800, and 976 nm) to ischemic-induced changes, with particular emphasis on the 976 nm wavelength, which demonstrates superior tissue penetration and increased sensitivity to variations in blood perfusion and tissue density during ischemia. Optical markers such as spot-size widening, spatial intensity shifts, and central intensity decrease are identified as reliable indicators of ischemia. Our findings suggest that multiwavelength reflectance analysis, particularly in the near-infrared range, provides a practical, noninvasive approach for continuously monitoring ischemic strokes. This technique indicates potential for improving early diagnosis and real-time monitoring of cerebral perfusion, which allows for continuous, noninvasive monitoring of cerebral perfusion and management of ischemic strokes, improving patient outcomes and clinical decision-making.