Abstract
The authors aimed to represent ultrasound examination of enthesis which precisely visualize its structure, assess its thickness, echogenicity and presence of Power Doppler signal. Typical US signs of acute or active enthesitis are: hypoechogenicity, thickening (with or without mixed echotexture, and with or without blurring of the tendon margins), and Doppler signal at the cortical bone insertion.
Erosions and cortical irregularities, enthesophytes and calcification belong to structural signs of chronic and/or inactive US enthesitis. Localization of Power Doppler enables distinguishing active inflammatory process (enthesitis) from degenerative or mechanic enthesopathy.
In recent years, several enthesitis scoring indices have been developed. First and so far mostly used is the GUESS index (Glasgow ultrasound entesitis scoring system), others are MASEI (Madrid sonographic enthesitis index) and SEI (Spanish enthesitis index).
Enthesitis scoring systems has led to standardization and quantification of ultrasound findings typical for enthesitis and enabled to investigate prevalence of enthesitis in patients with spondyloarthropathy. Previous studies demonstrated a high prevalence of entesitis by ultrasonography (45-60%), while significantly lower prevalence was observed by clinical examination (14-22%).
Most frequently affected enthesis according to the mentioned reports were: Achilles tendon, quadriceps tendon, distal part of ligamentum patellae, proximal part of ligamentum patellae and plantar fascia. Authors describe also the use of ultrasound follow-up for monitoring therapeutic response of biologic and non-biologic agents.
The last part of this article is dedicated to the role of ultrasound vs. MRI in detecting enthesitis.