Figure 4 Spinal infection. This 50-year-old man who was previously healthy reported acute-onset low back pain which progressively worsened over the prior week, causing him to be unable sleep or stand upright. Lumbar magnetic resonance imaging showed a 3.2×3.1×3.0-centimeter T2-weighted hyperintense lobulated lesion at the left L5/S1 paraspinal region involving the left psoas muscle (arrowhead in axial T2-weighted axial image), with apparent connection with the left side of the intervertebral disc. The chiropractor consulted with an on-site orthopedic surgeon and referred the patient to the emergency department, where he was treated for a psoas abscess and spondylodiscitis. Arrow added by RT using GNU Image Manipulation Program (Version 2.10.30).