According to a recently published study in 'The Journal of Rheumatology', the Color Doppler ultrasound (CDUS) depicted adequate diagnostic properties for detection of sacroiliitis and is also a useful tool in patients with inflammatory back pain (IBP).

The investigators examined the diagnostic value of Color Doppler ultrasound (CDUS) for the detection of sacroiliitis in patients with IBP. Consecutive patients with IBP with suspected axial spondyloarthritis (SpA), except without a definitive diagnosis, were included in this study. The control group had consecutive patients with defined SpA with axial involvement. Within the same week, all the patients underwent clinical assessment, magnetic resonance imaging (MRI), and CDUS of sacroiliac joints (SIJ). Considering MRI as the gold standard, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for the diagnosis of sacroiliitis by CDUS were evaluated.

All in all, there were 198 SIJ examined in 99 patients (36 having the previous SpA). There were 61 men (61.6%), with a mean age of 39.8 years (SD 11.3) and a median disease duration of 24 months.
Overall, it was found that CDUS had good sensitivity with exquisite specificity for the detection of inflamed SIJ, defined by the MRI. 

"The results need to be verified in other larger cohorts", as mentioned by Rosa JE and the fellow investigators.