Pilot study of non-invasive tissue perfusion imaging in Peripheral Arterial Disease with MultiSpectral Optoacoustic Tomography

Peripheral arterial disease (PAD) of the limbs is a progressive and common disease. Symptoms of PAD include pain, and when the disease progresses to critical limb-threatening ischemia, resting pain and non-healing ulcers. The symptoms are the result of impaired tissue perfusion. To determine the severity of PAD, but even more important to localize ischemic regions in the lower extremity, tissue perfusion imaging may be extremely relevant. Today, the most common studied modality for non-invasive tissue perfusion measurements is transcutaneous partial pressure of oxygen (TcPO2). Unfortunately this technique has some limitations. It is operator dependent, time consuming and not well suited for everyday clinical use. A potentially more appropriate technique is Multi-Spectral Optoacoustic Tomography (MSOT). It is a new non-invasive imaging technique with real-time visualization of the ratio of oxygenated and deoxygenated haemoglobin, and therefore tissue oxygen saturation. As such, anatomical and perfusion characteristics of blood vessels can be combined. Therefore, this imaging modality has the potential to evaluate the effects of treatments in patients with PAD quantitatively and accurately. This study aims to investigate the feasibility and clinical performance of tissue perfusion imaging with MSOT in the lower extremity of healthy volunteers, claudicants and patients with critical limb-threatening ischemia. The main objective is to optimize MSOT to quantify tissue saturation by resolving oxygenated and deoxygenated haemoglobin in these three categories of subjects. The second objective is to develop a standardized measurement protocol for the MSOT imaging in the lower extremity to optimize precision and accuracy of the measurements. Other objectives are to evaluate tissue saturation determined with MSOT in reference to standard diagnostics such as ankle/brachial index (ABI), toe systolic blood pressure (TBP), Doppler ultrasound and TcPO2 measurements. The final objective is to visualize the affected arteries and to determine tissue perfusion values before and after supervised exercise in claudicants or revascularization procedures in patients with critical limb-threatening ischemia.

We hypothesize that MSOT imaging can determine tissue perfusion in the lower extrimity of healthy volunteers and patients with PAD, and therefore detect disease, disease progression and can detect changes in tissue perfusion following treatment for PAD.

Before and after treatement

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