Multispectral optoacoustic tomography of peripheral arterial disease based on muscle hemoglobin gradients-a pilot...

Current imaging assessment of peripheral artery disease (PAD) relies on anatomical cross-sectional visualizations of the affected arteries. Multispectral optoacoustic tomography (MSOT) is a novel molecular imaging technique that provides direct and label-free visualizations of soft tissue perfusion and oxygenation.

MSOT was prospectively assessed in a pilot trial in healthy volunteers (group n₁=4, mean age 31, 50% male and group n₃=4, mean age 37.3, 75% male) and patients with intermittent claudication (group n₂=4, mean age 72, 75% male, PAD stage IIb). We conducted cuff-induced ischemia (group n₁) and resting state measurements (groups n₂ and n₃) over the calf region. Spatially resolved mapping of oxygenated (HbO₂), deoxygenated (Hb) and total (THb) hemoglobin, as well as oxygen saturation (SO₂), were measured via hand-held hybrid MSOT-Ultrasound based purely on hemoglobin contrast.

Calf measurements in healthy volunteers revealed distinct dynamics for HbO₂, Hb, THb and SO₂ under cuff-induced ischemia. HbO₂, THb and SO₂ levels were significantly impaired in PAD patients compared to healthy volunteers (P<0.05 for all parameters). Revascularization led to significant improvements in HbO₂ of the affected limb.

Clinical MSOT allows for non-invasive, label-free and real-time imaging of muscle oxygenation in health and disease with implications for diagnostics and therapy assessment in PAD.