Feasibility of Laser Speckle-Based Perfusion Imaging in an Ex-Vivo Liver Model

Objective: Advancing microcirculatory perfusion assessment methods is crucial for evaluating organ status during ex-vivo organ preservation and expanding the donor pool. This study demonstrates the feasibility of microcirculatory perfusion imaging in an ex-vivo liver model under normothermic machine perfusion, using two non-contact imaging techniques: laser Doppler perfusion imaging (LDPI) and laser speckle contrast imaging (LSCI).Methods and procedures: An ex-vivo porcine liver was perfused with oxygenated blood for 3 hours. Blood samples were collected every 30 minutes from the hepatic artery and portal vein to evaluate the liver&#x2019;s overall status. Each of the five liver lobes was imaged every 15 minutes using both the in-house developed LDPI and wireless LSCI devices. Temporally averaged perfusion maps were analyzed to assess spatiotemporal blood flow. Then, correlations between LDPI and LSCI perfusion indices were evaluated.Results: Spatiotemporal perfusion images showed detailed superficial microcirculatory perfusion across five imaged lobes. High correlations between LDPI and LSCI indices were observed in lobes <inline-formula> <tex-math notation="LaTeX">$3-5$ </tex-math></inline-formula> (<inline-formula> <tex-math notation="LaTeX">${R}^{2}=0.81$ </tex-math></inline-formula>), which were well-perfused. Blood lactate levels increased over time, indicating a shift in metabolic activity due to ischemia. Also, correlation of LSCI perfusion indices with pH (<inline-formula> <tex-math notation="LaTeX">${R}^{2}_{\max .}=0.95$ </tex-math></inline-formula>) was observed.Conclusion: The ex-vivo liver model mimics in-vivo perfusion under controlled experimental conditions. LDPI and LSCI provide rapid, independent assessments of local microcirculatory blood flow, demonstrate a high inter-technique correlation, and reflect the overall deterioration of liver status, as evidenced by blood gas parameters.Significance: A compact, wireless LSCI system&#x2014;validated against LDPI&#x2014;enables non-invasive evaluation of microcirculatory status and serves as a complementary tool for assessing deep tissue viability. Clinical and Translational Impact Statement&#x2014;We introduce a wireless, compact, and non-contact LSCI system (validated by LDPI) enabling microcirculatory assessment during machine perfusion, complementing deep tissue medical imaging methods and blood gas analysis to enhance organ viability evaluation and support pre-transplantation treatment decisions (Category: Pre-Clinical Research).