Kanna RM, et al. - The efficacy of MRI findings vs tissue studies in the diagnosis of unilateral sacroiliitis (US) were estimated in the retrospective analysis. They observed unilateral gluteal pain (100%) and positive Patrick’s test (91.9%) in 33 subjects with MRI characteristics of US. They diagnosed infective sacroiliitis (A) in 60.6% of cases based on the MRI features of severe subchondral marrow edema, widening of joint space, intra-articular abscess and periarticular muscle abscess. Based on MRI criteria ie, subchondral sclerosis with minimal edema, erosions, maintained joint space without abscess/destruction, a total of 13 cases had features of inflammation (B). They found tissue evidence of infection positive in 65% of subjects in group A whereas it was negative in all group B candidates. They recommended the percutaneous biopsy for infective sacroiliitis.