Real-time sonoelastography of Achilles tendon in patients with ankylosing spondylitis.

Objective: Real-time sonoelastography (SE) is a new ultrasound-based imaging technique that provides information on tissue elasticity and stiffness. We determined the efficacy of SE for assessing Achilles tendon abnormalities in patients with ankylosing spondylitis (AS).

Methods: Forty-one consecutive AS patients and 32 asymptomatic healthy subjects were enrolled. Achillodynia was scored on a 0- to 100-mm visual analog scale. A high-resolution ultrasound machine equipped with an elastography-compatible linear probe was used to perform bilateral B-mode ultrasound, Doppler ultrasound, and SE examinations of Achilles tendons. Tendons were divided into proximal, middle, and distal segments. B-mode examinations included tendon thicknesses, echotextures, and enthesopathic findings. SE using color-coded images was performed in the same areas. Normal consistent tendon structures were coded as blue or green, and moderately (yellow) or severely (red) softened areas were considered pathological.

Results: The distal third of the Achilles tendons was the most commonly affected part in the AS patients compared with healthy subjects (p = 0.001), whose middle third was more commonly affected. Achillodynia intensity tended to be higher in patients with pathological B-mode or SE examination findings (p = 0.09 and p = 0.07 respectively). Softening detected by SE in the distal third was associated with enthesopathy findings such as calcaneal bone erosions (Fisher's X (2), p = 0.07) and tendinous enlargement (Fisher's X (2), p = 0.001). B-mode and SE findings had moderate to good correlation in the assessment of Achilles tendon abnormalities.

Conclusions: Sonoelastography may be useful for the evaluation of tendon abnormalities in patients with AS; in addition; it may be useful for the evaluation of other inflammatory rheumatic conditions.