Ultrasound and Shear Wave Elastography Assessment of Entheses in Psoriatic Arthritis

Psoriatic arthritis (PsA) is a chronic inflammatory musculoskeletal disease associated with psoriasis and characterized by peripheral arthritis, axial involvement, dactylitis, and enthesitis. Enthesitis, defined as inflammation at the insertion sites of tendons, ligaments, fascia, or joint capsules into bone, is considered one of the hallmark manifestations of PsA and may contribute substantially to pain, functional impairment, and structural damage. Early and accurate assessment of enthesitis is essential for disease evaluation and management. However, clinical examination alone has limited sensitivity for detecting subclinical or early entheseal inflammation. Musculoskeletal ultrasonography has become an important imaging modality for the evaluation of enthesitis. Grayscale ultrasonography allows assessment of structural abnormalities such as tendon thickening, hypoechogenicity, calcifications, enthesophytes, erosions, and bursitis, while Power Doppler ultrasonography enables the detection of active vascularization associated with ongoing inflammation. In addition, shear wave elastography (SWE) is an ultrasound-based technique that quantitatively measures tissue stiffness and may identify biomechanical changes that are not detectable with conventional ultrasonography. Combining grayscale ultrasonography, Power Doppler ultrasonography, and SWE may provide a more comprehensive evaluation of entheseal involvement in PsA. This is a single-center, observational, cross-sectional study conducted at Marmara University Pendik Education and Research Hospital. The study will include patients with psoriatic arthritis fulfilling the CASPAR classification criteria and age- and sex-matched healthy controls. Bilateral enthesis sites included in the Madrid Sonography Enthesitis Index (MASEI) will be evaluated using grayscale ultrasonography, Power Doppler ultrasonography, and shear wave elastography. Clinical assessments will include disease activity indices, patient-reported outcome measures, functional assessments, and laboratory inflammatory markers. The primary objective of the study is to compare ultrasonographic and elastographic findings between patients with PsA and healthy controls. Secondary objectives are to investigate the relationships between imaging findings and disease activity, disease duration, clinical characteristics, functional status, and laboratory parameters. The study aims to determine the potential contribution of shear wave elastography, in combination with conventional ultrasonography and Power Doppler imaging, to the assessment of enthesitis in patients with psoriatic arthritis.