Ankylosing spondylitis

Romanus lesion: Anterior spondylitis: Earliest change; irregularities and erosions involving anterior and posterior edges of vertebral endplates; occur at the site of attachment of anulus fibrosus to vertebral endplate and hence regarded as enthesitis
Shiny corners: sclerotic changes of vertebral endplate
Andersson lesion (1937): Spondylodiscitis: seen in 8% of patients
Insufficiency Fracture: transdiscal or transvertebral due to porosis. It is non-inflammatory lesion where as Anderson lesion is inflammatory
Facet joint arthritis:blurring of joint clefts
Syndesmophytes: 15% of patients. bony outgrowths of the anterior vertebral edges. Plain radiograph is better than MR
Ankylosis: common in edges or centre
Active Romanus lesion: rim of low signal of endplate on T1 and increased signal on STIR; represents marrow edema or osteitis; can be anterior spondylitis or posterior spondylitis or marginal spondylitis when combined
Inactive Romanus lesion: high signal epiphyseal ring on T1 (postinflammatory fatty marrow degeneration).
Anderson lesion: disk related signal abnormalities of one or both vertebral halves of a diskovertebral unit; high signal on STIR and low on T1, often shape of hemisphere with lines of increased signal at interface between anulus and nucleus
(Normally disc is low on T1 and high on T2; endplate is int on T1 and low on T2)
Florid inflammation: disc is low on T1 and high on T2; endplate is low on T1 and high on T2
Post inflammatory fatty degeneration: disc is low on T1 and high on T2; endplate is high on T1 and low on T2
Ankylosis: disc and endplates are int on T1 and low on T2
Insufficiency fracture: Acute ones are low on T1 and late ones are high on T2
Facet joint arthritis: effusion, synovitis, erosions, marrow edema
Enthesitis: increased signal on STIR images, enhance on Gd FS T1; associated with osteitis of adjacent bone in spinous processes, which show high signal on STIR images. Thickening of the ligaments is better seen on T1
Syndesmophytes: inferior to plain radiograph. Low or high signal on STIR images
Ankylosis: iso to muscle on T1 and hypo on STIR images
Hermann KA et al. Spinal Changes in Patients with Spondyloarthritis: Comparison of MR Imaging and Radiographic Appearances. RadioGraphics 2005;25:559-569