AB1102 COLOR DOPPLER ULTRASOUND OF SACROILIAC JOINTS COMPARED WITH MAGNETIC RESONANCE IMAGING IN NON RADIOGRAPHIC SPONDYLOARTHRITIS

Abstract

Background:Magnetic resonance imaging (MRI) of sacroiliac joints (SIJ) can assess early inflammatory changes, thus allowing an early diagnosis of spondyloarthritis (SpA). However, its use in clinical practice may be limited by its cost, its duration and its limited availability. In this sense, ultrasound (US) has been suggested as a feasible and easy-to-apply alternative.Objectives:The objective of this study was to evaluate the validity of Color Doppler Ultrasound (CDUS) in early assessment of sacroiliitis, compared to MRI findings as the gold standard.Methods:A cross-sectional prospective monocentric study included patients attending the rheumatology department with suggestive signs of SpA between February 2014 and February 2017. Patients with pelvic radiography showing a confirmed sacroiliitis (grade 3 or 4) were not included. Eligible patients underwent US and MRI of SIJ. US examinations were performed by an experimented musculoskeletal radiologist blinded to MRI results. Vascularization within the SIJs was explored by the presence of a CDUS. When an artery was found, the resistive index (RI) was measured. The values of the RI ranged between 0 and 1. Doppler of each SIJ was considered as positive when RI was <0.75.Results:Forty-three patients were included: 10 men and 33 women, with an average age at inclusion of 40.2 ± 11.1 years [17-59]. The mean duration of symptoms was 46±37.5 months [6.6-180]. A personal history of uveitis was noted in 3 patients and of chronic diarrhea in 3 patients. Morning stiffness was noted in 72% (n=31) of patients. Good response to nonsteroidal anti-inflammatory drugs (NSAIDs) and to physical activity were respectively reported by 41.8% (n=18) and 58% (n=25) of patients. Sacroiliac compression test, distraction provocative test, sacral thrust test, Gaenslen’s test, Faber’s test (Patrick) and Mennel’s test were respectively positive in 39.5%, 32.5%, 48.8%, 23.2%, 32.5%, and 51.2% of the patients. Twenty-seven per cent of the patients were HLA-B27+. The MRI showed a confirmed sacroiliitis in 14 patients. Doppler signal was detected in 44 SIJ of 25 patients, of whom 14 SIJ of 8 patients showed bone marrow edema at MRI (p=0.054). At the joint level, considering MRI-proven sacroiliitis as the diagnostic standard, CDUS had a sensitivity of 70%, a specificity of 54.5%, a positive predictive value of 31.8%, and a negative predictive value of 85.7%. The spectral Doppler RI, averagely estimated at 0.74±0.12 [0.48-0.87], was not associated with the presence of sacroiliitis on MRI (p=0.747).Conclusion:US, an imaging technique increasingly used in the assessment of musculoskeletal diseases, has been suggested to detect active sacroiliitis [1, 2]. Our study revealed that in early SpA, CDUS may be useful to assess active inflammatory changes of SIJ since it had a sensitivity of 70%, despite a relatively reduced specificity. However, RI values, which are expected to be low in patients with active inflammation [3], were unrelated to the presence of sacroiliitis. Future studies on larger numbers of patients might be conducted to complete previous data.