Scoring of structural lesions

Fat metaplasia (FASSS) is scored as previously described,^{6 8} the scoring range is 0–456. The method for scoring erosions is similar to the method for scoring spine inflammation, except that erosions are only assessed in central sagittal slices. Anterior and posterior corner erosions are scored 1, non-corner erosion is scored 2, in DVUs in the thoracic and lumbar spine, a score of 1 is added for large corner lesions and a score of 2 is added for large non-corner lesions. Erosions are not scored in the facet joints or other posterior elements. The scoring range for the CANDEN spine erosion score is 0–320. To obtain the CANDEN spine new bone formation score, at each level, the presence of anterior corner ankylosis, posterior corner ankylosis and non-corner ankylosis are each scored as 0 (absent) or 6 (present), anterior corner, posterior corner and non-corner bone spurs are each scored as 0 (absent) or 2 (present), facet joint ankylosis is scored as 0 (absent) or 1 (present), and all individual lesion scores are summed. The new bone formation scores were chosen to be consistent with the scores used in the radiographic mSASSS system that assigns a score of 2 for bone spur and a score of 3 for ankylosis (in total a score of 6 for two ankylosed corners that are opposing each other). Scoring range for the CANDEN spine new bone formation score is 0–460; the vertebral body subscore has a range of 0–414 and the facet joints subscore has a range of 0–46.

The estimated reading time including data entry for obtaining the CANDEN spine inflammation score was not recorded systematically, but judged to be in the range of 10–45 min for all four timepoints depending on the amount of inflammation, similar to the SPARCC method in most cases. Total scoring time for inflammation and structural lesions in the spine were in the range 15–90 min per patient for four timepoints.