In this prospective, cross-sectional, observational study consecutive eligible subjects with FM, PsA, and a group of age- and sex-matched asymptomatic volunteers will undergo a research US examination of the dominant Achilles' tendon, knee medial collateral ligament and common extensor tendon of the elbow. Two operators under the supervision of a musculoskeletal radiologist will perform the US exam. B-mode and Power Doppler ultrasound of each tendon and ligament will be performed for morphological characterization. Then, shear wave elastography (SWE) and radiofrequency (RF) will be acquired. The shear wave speed (SWS) will be measured in the longitudinal plane using shear wave measurements. These features will be compared between groups. The HDK parameters (μ, 1/alpha, κ) will be computed offline, using RF sequences recorded in the longitudinal plane. Demographic features (participant age, sex, body mass index), the Leeds Enthesis Index (LEI) score assessed by the referring clinicians, and the self-administered Health Assessment Questionnaire (HAQ), Brief Pain Inventory (PBI) and Fibromyalgia Impact Questionnaire (FIQ) scores will be available for multivariate analyses.
This prospective, cross-sectional, observational study will include subjects with fibromyalgia (FM), psoriatic arthritis (PsA) and asymptomatic controls. Participants will undergo a research ultrasound (US) exam of the enthesis of the Achilles' tendon, the medial collateral ligament at the femoral epicondyle and the common extensor tendon at lateral epicondyle of the elbow in resting conditions. The research US exam will consist of shear wave elastography (SWE) and radiofrequency (RF) data acquisitions. SWE technology will allow quantification of the shear wave speed (SWS) reporting the elastic stiffness of the tissues under investigation. RF data will be used to estimate quantitative ultrasound (QUS) parameters characterizing the mean intensity μ (akin to B-mode echogenicity), acoustic inhomogeneity (1/alpha), and structural spatial organization of echoes (κ) in the tissue.