Characterizing sclerotic skin stiffness with Acoustic Radiation Force Impulse (ARFI) and Shear Wave Elasticity Imaging (SWEI)

Sclerotic skin diseases are associated with inflammation and fibrosis in the dermis, and these changes in collagen content with disease progression make this pathology amenable to being characterized with Acoustic Radiation Force Impulse (ARFI) and Shear Wave Elasticity Imaging (SWEI) methods. We characterized skin stiffness in healthy individuals at repeated three month intervals and compared sclerotic to healthy skin stiffness. ARFI and SWEI were implemented using a Siemens 14L5 linear array on an ACUSON S2000
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scanner. A single dermatologist performed all imaging in twenty-two patients. Normal and sclerotic skin stiffnesses were characterized by (1) mean ARFI displacement magnitude, and (2) group shear wave speed estimated using a Radon sum of shear wave velocity data. Imaging was performed at different anatomic sites, including the upper and lower back, arm, forearm, abdomen, thigh and calf. Five repeat data acquisitions were performed in each anatomic location. ARFI displacement and SWEI shear wave speeds were reconstructed in 96% of all acquisitions when the region of interest was exclusively contained in the dermis. Overall, ARFI and SWEI metrics showed no significant difference between contralateral imaging locations across different anatomic sites in healthy skin (p < 0.05). Mean shear wave speeds were >200% greater in sclerotic lesions than in contralateral healthy skin in patients with graft-versus-host disease (GVHD) (p < 0.01), and 25% greater in patients with morphea. ARFI displacements exhibited greater variability than shear wave speed in characterizing sclerotic skin, showing a 61% decrease compared to healthy skin in GVHD patients (p < 0.05) and a 19% decrease in morphea patients (p < 0.05). ARFI and SWEI are able differentiate sclerotic skin lesions from healthy skin, and studies are underway to evaluate their utility in longitudinally-monitoring disease progression and response to therapy. Additional study details, data and conclusions can be found in the full-length manuscript describing this work [1].