Clinical application of diagnostic techniques for tissue perfusion measurements

This thesis describes various diagnostic techniques for assessing tissue perfusion in patients with peripheral arterial disease (PAD) and patients undergoing reconstructive surgery. Measuring tissue perfusion, especially superficial perfusion of the skin, is relevant for diagnosis of diseases, it can be used during surgery as a guide to the practitioner, and for early detection of complications. The dissertation investigates various techniques for pre-, intra- and post-operative application.Conventional diagnostic techniques exist for PAD patients, but better methods such as tissue perfusion measurements are needed. Existing techniques, such as transcutaneous oxygen measurements (TcPO2), are the most widely used and researched but not yet widely implemented as a gold standard. New techniques such as laser speckle contrast imaging and hyperspectral imaging are mentioned as promising, but more research is needed for clinical use. The dissertation also focuses on hyperspectral imaging (HSI) as a technique for tissue perfusion measurements. It describes a standardized measurement protocol and the reliability of HSI measurements. Furthermore, the dissertation investigates the application of HSI and thermal imaging (TI) for endovascular treatment (EVT) in PAD patients. Endovascular infrapopliteal re-interventions are being evaluated for patients with chronic limb-threatening ischemia (CLTI). Although technically successful, outcomes and "patency" are moderate.Finally, the dissertation focuses on the use of diagnostic techniques for tissue perfusion in free-flap reconstructive surgery. Techniques such as Indocyanine Green Fluorescence Angiography (ICGA), HSI and TI are examined for both intra- and postoperative evaluation of flap perfusion.The dissertation discusses the findings of these studies and makes recommendations for future research and clinical applications of tissue perfusion diagnostic techniques