Table 2.

Scoring rules

CANDEN MRI spine inflammation score	The following lesions are scored as 0 (absent) or 1 (present): aCIL, pCIL, NIL, aLIL, pLIL, FIL, TIL, RIL, SPIL and STIL. A score of 1 is added for large aCIL and pCIL. Non-corner lesions (NIL) are scored as 0 (absent) or 2 (present), and a score of 2 is added for large non-corner lesions (NIL). The CANDEN MRI spine inflammation score has a total scoring range of 0–614. The vertebral body subscore has a score range of 0–464 (11 cervical endplates from C2 to C7, each with a maximum score of 4, 35 thoracic/lumbar endplates from T1 to S1 each with a maximum score of 12). The posterior elements subscore has a score range of 0–150 (facet joints at all 23 levels from C2/C3 to L5/S1, transverse process at 17 levels from T1 to L5, rib at 12 levels from T1 to T12, spinous process at 23 levels from C2 to L5, soft tissue inflammation at 23 levels from C2/C3 to L5/S1). The CANDEN MRI spine inflammation score may also be divided into the following four subscores: A, ‘Vertebral body corner inflammation subscore’, defined as the sum of the anterior and posterior corner lesions, and anterolateral and posterolateral vertebral body lesions (posterolateral vertebral body lesions only at levels T12/L1 to L5/S1), which may predominantly represent enthesitis related to the anterior and posterior longitudinal ligament and the annulus fibrosus (range 0–254). B, ‘Spondylodiscitis subscore’, defined as the sum of non-corner vertebral body lesions, which may predominantly represent inflammation from the disc or endplate itself (range 0–162). C, ‘Facet joint inflammation subscore’, defined as the sum of facet joint lesions, representing inflammation of the synovial facet joints (range 0–46). D, ‘Posterolateral elements inflammation subscore’, defined as the sum of rib, transverse process, spinous process, soft tissue inflammation and posterolateral vertebral body lesions (posterolateral vertebral body only at levels C7/T1 to T11/T12 because pLIL in the thoracic spine is considered to be related to the costovertebral joint), representing inflammation related to these synovial joints and enthesitis of ligaments of the posterior elements of the spine (range 0–152).
CANDEN MRI spine fat score	The following lesions are scored as 0 (absent) or 1 (present): aCFAT, pCFAT, aLFAT, pLFAT and FFAT. A score of 1 is added for large aCFAT and pCFAT. Non-corner lesions (NFAT) are scored as 0 (absent) or 2 (present), and a score of 2 is added for large non-corner lesions (NFAT). The total scoring range for the CANDEN MRI spine fat score is 0–510. The range for the vertebral body subscore is 0–464 (11 cervical endplates each with a maximum score of 4, 35 thoracic/lumbar endplates each with a maximum score of 12). The range for the fat posterior elements subscore is 0–46 (facet joints at all 23 levels).
CANDEN MRI spine bone erosion score	The following lesions are scored as 0 (absent) or 1 (present): aCOBE, pCOBE and FABE. A score of 1 is added for large aCOBE and pCOBE. The total scoring range for the CANDEN MRI spine bone erosion score is 0–208. The range for the vertebral body subscore is 0–162 (11 cervical endplates each with a maximum score of 2, 35 thoracic/lumbar endplates each with a maximum score of 4). The range for the posterior elements subscore is 0–46 (facet joints at all 23 levels).
CANDEN MRI spine new bone formation score	Anterior corner, posterior corner and non-corner ankylosis are scored as 0 (absent) or 6 (present). Anterior corner, posterior corner and non-corner bone spurs are scored as 0 (absent) or 2 (present). Facet joint ankylosis is scored as 0 (absent) or 1 (present). The total scoring range for the CANDEN MRI spine new bone formation score is 0–460. The range for the vertebral body subscore is 0–414 (23 levels with a maximum score of 18). The range for the posterior elements subscore is 0–46 (facet joints at all 23 levels).

aCFAT, anterior corner fat lesion; aCIL, anterior corner inflammatory lesion; aCOBE, anterior corner bone erosion; aLFAT, anterolateral vertebral body fat lesion; aLIL, anterolateral vertebral body inflammatory lesion; CANDEN, Canada-Denmark; FABE, facet joint bone erosion; FFAT, facet joint fat lesion; FIL, facet joint inflammatory lesion; NFAT, non-corner fat lesion; NIL, non-corner inflammatory lesion; pCFAT, posterior corner fat lesion; pCIL, posterior corner inflammatory lesion; pCOBE, posterior corner bone erosion; pLFAT, posterolateral vertebral body fat lesion; pLIL, posterolateral vertebral body inflammatory lesion; RIL, rib inflammatory lesion; SPIL, spinous process inflammatory lesion; STIL, soft tissue inflammatory lesion; TIL, transverse process inflammatory lesion.