Sonographic detection of sacroiliitis - An appraisal

In the last decade, rheumatology saw an exponential rise in the use of Musculoskeletal Ultrasound (MSUS) as a diagnostic imaging modality. The ability of MSUS to detect inflammation of the sacroiliac joints (SIJ) in Spondyloarthritis (SpA) was also tested. Studies on sacroiliitis utilized different MSUS technologies: B-Mode US (BM US) to search for intraarticular effusion, synovitis, and measure the joint width; color Doppler (CD US) to detect low velocity blood flow as a marker for inflammation and Contrast-Enhanced US (CE US), able to show increased vascularity in the deeper part of the SIJ. Though, in general, most of these studies have promising results in the ability of MSUS to detect sacroiliitis, there are some important limitations of this method due to both anatomical and technological reasoning. The aim of this narrative review is to briefly outline the new data on US application to diagnose sacroiliitis and to discuss it in relation with SIJ anatomy. In addition, some important pitfalls that could be encountered when scanning these joints are noted. Plamen Todorov*1,2 & Anastas Batalov1,2