Transmissive-Detected Hyperspectral Imaging for Single-Vessel-Resolution Blood Oxygen Mapping

Objective: This study proposed a transmissive-detected hyperspectral imaging (TD-HSI) strategy for blood oxygen mapping in order to address the limitation of reflective HSI in obtaining high-resolution blood oxygen information from deep tissues. Impact Statement: This innovative TD-HSI has great potential in promoting noninvasive, high-resolution in vivo blood oxygen monitoring and provides a powerful tool for the study of tissue oxygenation and microcirculation diseases. Introduction: Oxygen saturation (SO₂) served as a critical indicator reflecting physiological states. However, strong scattering of tissue prevents accurate SO₂ mapping with promising resolution, which also limited the depth of reflective HSI. Methods: Monte Carlo simulations were employed to theoretically evaluate the deep-tissue measurement of SO₂ between conventional reflective-detected HSI (RD-HSI) and TD-HSI. Then, in vivo TD-HSI system was used to observe the impact of hypoxia on individual arteries and veins at various locations in mice, and monitor the SO₂ fluctuations during subcutaneous tumor growth over a 1-week period. Results: The simulations showed that TD-HSI remarkably extended the depth of accurate SO₂ detection and boasted approximately 6-fold greater precision in detecting SO₂ variations. In vivo experiments validated the efficacy of TD-HSI, demonstrating its capability to achieve SO₂ mapping in mice skin with single-vessel resolution, a feat not possible with RD-HSI. Conclusion: We conducted a comprehensive evaluation of the capability of TD-HSI strategy for deep-tissue blood oxygen imaging. Our data demonstrated that TD-HSI offered substantial improvements over conventional RD-HSI in noninvasively acquiring blood oxygen information in deep tissue.