Ultrasound characteristics of gouty tophi in the olecranon bursa and evaluation of their reproducibility.

OBJECTIVES: To describe the ultrasound characteristics of gouty tophi in the olecranon bursa and to evaluate their reproducibility. METHODS: A prospective study of the ultrasound features of 35 sites of tophi nodulations in the elbows of 31 men (mean 54.6 years). The findings were evaluated dynamically following pre-established standards. The static images were evaluated by another radiologist and were reviewed by the first examiner. RESULTS: The most frequent characteristics of tophi are: hyperechogenicity (91.7%), poorly defined contours (88.6%), multiple grouped nodules (85.6%) and heterogeneity (68.6%). Intra-observer agreement is almost perfect for echogenicity (K = 1.0), moderate for the involvement of the olecranon bursa (K = 0.47) and fair for other characteristics. Inter-observer agreement is substantial for the echogenicity (K = 0.65), fair for the echotexture (K = 0.27) and the presence of a perilesional hypoechoic halo (K = 0.34) and slight for other characteristics. CONCLUSIONS: The most frequent characteristic of tophi is hyperechogenicity. The intra-observer and inter-observer concordance for echogenicity are almost perfect and substantial, respectively. Knowledge of characteristics of the tophi in the elbow and their intra and inter-observer reproducibility may assist in establishing parameters for monitoring treatment and setting up criteria for differential diagnosis of processes involving the olecraneon bursa.

Ultrasound features of tophi in chronic tophaceous gout.

OBJECTIVE: To describe the different and lesser-known ultrasound features of tophi in chronic tophaceous gout. METHODS: Ultrasound images of 138 affected areas were analyzed from 31 patients with gout, using high-quality broadband linear transducers (frequency range of 8-14 MHz). Tophi were classified relative to echogenicity, echotexture, contours, number and the presence or absence of hypoechoic halo. The duration of illness was correlated with the presence of calcifications in tophi. RESULTS: Hyperechoic tophi were seen in 133 areas (96.3%); these were most frequently hyperechoic and heterogeneous (37.6%) or hyperechoic and heterogeneous with calcification (32.6%). Contours were found to be poorly defined in 115 (83.3%) areas. Multiple grouped tophi were seen in 85 areas (61.6%) and 50 areas (36.2%) had individual tophi. In 77 examined areas (55.8%), there was a hypoechoic halo around the tophi. There was no correlation between illness duration and presence of calcifications on tophi. CONCLUSIONS: Tophi are generally hyperechoic, heterogeneous, with poorly defined contours, multiple grouped and surrounded by an anechoic halo. Individual tophus and the absence of association between illness duration and the presence of calcification are newly described features. This study of tophaceous gout by ultrasound may contribute to the diagnostic elucidation of patients with clinically atypical gout and show its diverse characteristic forms of presentation.

Sonographic description and classification of tendinous involvement in relation to tophi in chronic tophaceous gout.

OBJECTIVE: To describe and classify the varied ultrasound features of tendinous involvement in relation to tophi in chronic tophaceous gout so that they are better recognised. METHODS: Ultrasound images of 138 affected areas from 31 patients with chronic tophaceous gout were analysed using high-quality broadband linear transducers. The relationship between tendon and tophi was classified, and the inter-observer agreement regarding classification was analysed. RESULTS: Tophi envelopment in the tendon was the most frequent characteristic (45%) followed by no relationship between tophi and tendon (41%), tophi at the insertion site of the tendon (7%), extrinsic compression (6%) and tophi within the tendon (1%). The inter-observer concordance on classification of the relationship between tophi and tendon was measured using McNemar's test with P < 0.001 (χ(2) = 30.0, degree of freedom = 9) and kappa test = 0.627 (P < 0.001), indicating substantial inter-observer concordance. CONCLUSION: Tophi generally envelope the tendon or there is no relationship between them. Tophi can also be found at the insertion site of the tendon, cause extrinsic compression or be located inside the tendon. There is substantial inter-observer agreement for ultrasound classification of tendon involvement by tophi. This study contributes to diagnostic elucidation and shows the diverse characteristic forms of tendon involvement by tophi.