This clinical study evaluates the efficacy and accuracy of Multispectral Optoacoustic Tomography (MSOT) and Ultrasound Localization Microscopy (ULM) for imaging and diagnosing vascular malformations (venous, arteriovenous, lymphatic). The study aims to enhance diagnostic precision and improve treatment planning through advanced non-invasive imaging techniques.

This study aims to investigate whether Multispectral Optoacoustic Tomography (MSOT) and Ultrasound Localization Microscopy (ULM) can accurately differentiate between lymphatic, venous, and arteriovenous vascular malformations. MSOT can determine oxygen levels based on the expected low oxygen content in venous blood, high oxygen content in arterial blood, and the absence of oxygen in lymphatic fluid. Additionally, ULM, utilizing microbubbles, measures blood flow velocities, which may help identify and distinguish these malformations or their mixed forms.

To date, vascular malformations of blood and lymphatic vessels are commonly diagnosed using cross-sectional imaging techniques such as ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI). MSOT introduces a novel, non-invasive diagnostic approach that enables the assessment of oxygenated hemoglobin concentrations and oxygen levels in blood and tissue. Previous studies (e.g., MSOT_IC, MSOT_PI) demonstrated the capability of MSOT to visualize muscle perfusion in patients with peripheral arterial disease. Moreover, it has successfully identified muscle structures and the clinical severity of Duchenne muscular dystrophy by detecting endogenous biomarkers like collagen and lipids.

The objective of this study is to utilize MSOT and ULM as supplementary diagnostic tools to conventional imaging methods to accurately identify and distinguish between venous, arteriovenous, and lymphatic malformations in patients. This approach has the potential to reduce exposure to ionizing radiation from CT scans and minimize the need for resource-intensive MRI procedures in the future.

Inclusion Criteria:

• Confirmed vascular malformations (arteriovenous, venous, or lymphatic).
• ≥18 years old and able to give their consent

Exclusion Criteria:

• No imaging for diagnostic confirmation has been performed or is planned.
• Lack of written consent
• <18 years old
• Safety concerns of the study physician (a patient with physical, psychological, or psychiatric conditions that, in the opinion of the study physician, could compromise the patient's safety or the quality of the data, thereby making the patient an unsuitable candidate for the study).

The study population consists of patients (≥18 years old) with diagnosed vascular malformations. These may be of lymphatic, venous, or arteriovenous origin.