Figure 26.

Imaging psoas sign – axial T2W (A) magnetic resonance (MR) image through the lower lumbar spine demonstrates hyperintensity within the medial aspect of the right psoas muscle adjacent to the L4-L5 intervertebral disc (arrowheads), compatible with the imaging psoas sign in this case of L4-L5 acute pyogenic spondylodiscitis. Axial T1W post-contrast fat-suppressed (B) MR image at the same level shows similar inflammatory enhancement within the right psoas muscle (arrow) and enhancing bone marrow oedema