Muscle Perfusion in Patients With PAD by Non-invasive MSOT

The aim of the proposed study is to define an independent parameter for the diagnostic assessment of the perfusion situation of the calf muscle based on Multispectral Optoacoustic Tomography (MSOT) in a cross-sectional collective of healthy volunteers and patients with PAD. The gold standard is a previously performed angiography of the pelvic and femoral vessels based on routine diagnostics, this Imaging is not mandatory for healthy Control group (study group 1). An independent validation group (study group 2) will validate the results found in study group 1.

Peripheral arterial occlusive disease (PAD) is one of the most common diseases of the elderly with an overall prevalence of about 3-10%. As life expectancy increases, new treatment concepts and new diagnostic procedures are needed. In addition to the possibility of endovascular treatment and open surgery, in some cases there is also the possibility of a conservative therapeutic approach, e.g. with medication.

To date, the only independent non-invasive validation of these treatment options is the measurement of macrocirculation in the form of Color-Coded Vascular Duplex Sonography (CCDS), the Ankle Brachial Index (ABI) or the measurement of walking distance. The S3 guideline for diagnosis, therapy and medical aftercare of PAD published 2015 by the DGA (Deutsche Gesellschaft für Angiologie und Gefäßmedizin \[German Society for Angiology and Vascular Medicine\]) recommends aftercare in the sense of clinical examinations, especially for patients after vascular surgery. For the validation measures already mentioned, however, there are not infrequent patient groups for which these methods provide only insufficient or unusable results (diabetes mellitus, terminal renal failure). In these cases, independent verification of the success of the therapy performed would have to be performed using angiography (digital subtraction angiography, CT angiography or MR angiography). However, this is not routinely performed in the respective patient populations due to the associated risks (including radiation exposure, contrast agent administration, invasiveness).

Multispectral Optoacoustic Tomography (MSOT) now provides a new non-invasive diagnostic tool that may be able to fill this diagnostic gap.

The aim of this cross-sectional study is to define an independent parameter using the MSOT method, which allows a statement about the current perfusion situation of the lower extremity and correlates with the angiography, which is considered the gold standard. For this purpose, patients of different PAD stages, who already underwent routinely angiographies in advance, will be included. In addition, a control group of healthy volunteers (prior angiography not obligatory) will be examined.

Eligibility Criteria:
Inclusion criteria:

* Patients with manifest PAD stages II - IV according to Fontaine or category 1-6 according to Rutherford
* Adult (\>18 years) persons who are able to give their consent
* Patients in whom angiography has been performed as part of routine diagnostics (independent of the study) or in accordance with current guidelines, or has been indicated and the patients has given consent

Exclusion criteria:

* Patients with PAD stage I according to Fontaine or category 0 according to Rutherford
* Underage persons
* Missing consent form
* Patients with manifest PAD in whom angiography is not indicated
* Exclusion due to safety concerns of the study physician (patient with a physical, mental or psychiatric illness which, in the opinion of the study physician, would compromise the safety of the patient or the quality of the data and thus make the patient an unsuitable candidate for the study)