Background The 18-FDG PET/CT is an objective tool employed for the diagnosis of Takayasu arteritis and also is used for the assessment of disease activity of this vasculitis.¹ There are few clinimetric scores developed for Takayasu clinical activity assessment such as the Indian Takayasu Clinical Activity Score (ITAS2010/ITAS.A),² the National Institutes of Health criteria (NIH score) from USA³ and the Mexican effort by Dabague-Reyes (DR score).⁴ The validity and utility of 18-FDG PET/CT to measure the disease activity by studying wall enhancement compared to the clinimetric assessment has been slightly studied.

Objectives To explore the agreement between 18-FDG PET/CT and the clinimetric tools for the estimation of Takayasu activity in one national reference centre.

Methods The clinical records of patients that had performed an 18-FDG PET/CT were consecutively included. The required information to fulfil the ITAS2010, ITAS.A, NIH and DR were gathered from clinical charts. The cut-off points we used are the following: SUVmax ≥2.1 for 18-FDG PET/CT, for ITAS2010 ≥2 points, for ITAS.A≥4 points, for NIH≥2 points and for DR ≥5 points. Kappa index was calculated, comparing SUVmax with all the clinimetric measures. As an exploratory exercise, ROC curves were performed. A p value less than 0.05 was considered statistically significant.

Results Thirty six clinical records were reviewed. There was enough information to score ITAS2010 in 31 patients, ITAS.A in 28 patients, NIH and DR in 35 patients each. In our patients, moderate agreement was observed between 18-FDG PET/CT and DR score (Kappa=0.542, p=0.001). A tendency of weak agreement was observed with the NIH score (Kappa=0.215, p=0.086) and ITAS.A (kappa=0.351, p=0.063). There was no agreement with ITAS2010 (Kappa=0.107, p=0.519). Significant AUC were observed with DR (AUC=0.817, p=0.005) and NIH (AUC=0.756, p=0.025); however, this results were not obtained with ITAS2010 (AUC=0.675, p=0.124) and ITAS.A (AUC=0.697, p=0.083).

Conclusions There was no strong agreement between 18-FDG PET/CT and any of these activity indices. On the other hand, these data suggest that the best disease activity tool in Mexican patients were DR and the NIH scores. Comparative studies in other populations are warranted.

References [1] Tezuka D, et al. Role of FDG PET-CT in Takayasu arteritis: sensitive detection of recurrences. JACC Cardiovasc Imaging. 2012;5:422–9.

[2] Misra R, et al. Development and initial validation of the Indian Takayasu Clinical Activity Score (ITAS2010). Rheumatology (Oxford). 2013;52:1795–801.

[3] Kerr G, et al. Takayasu Arteritis. Ann Intern Med. 1994;120:919–929

[4] Dabague J, Reyes A. Takayasu arteritis in Mexico: A 38-year clinical perspective through literature review. Int J Cardiol. 1996;54 Suppl:S103–9.

Disclosure of Interest None declared