Low-dose CT detects more progression of bone formation in comparison to conventional radiography in patients with ankylosing spondylitis: results from the SIAS cohort.

OBJECTIVES: To compare the CT Syndesmophyte Score (CTSS) for low-dose CT (ldCT) with the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) for conventional radiographs (CR) in patients with ankylosing spondylitis (AS). METHODS: Patients with AS in the Sensitive Imaging in Ankylosing Spondylitis cohort had lateral cervical and lumbar spine CR and whole spine ldCT at baseline and 2 years. CR and ldCT images were scored by two readers, paired by patient, blinded to time order, per imaging modality. For the total score analysis, we used average scores of readers per corner on CR or quadrant on ldCT. For the syndesmophyte analysis we used individual reader and consensus scores, regarding new or growing syndesmophyte at the same corner/quadrant. RESULTS: 50 patients were included in the syndesmophyte analysis and 37 in the total score analysis. Mean (SD) status scores for mSASSS (range 0-72) and CTSS (range 0-552) at baseline were 17.9 (13.8) and 161.6 (126.6), and mean progression was 2.4 (3.8) and 17.9 (22.1). Three times as many patients showed new or growing syndesmophytes at ≥3 quadrants on ldCT compared with ≥3 corners on CR for individual readers; for consensus this increased to five times. In 50 patients, 36 new or growing syndesmophytes are seen on CR compared with 151 on ldCT, most being found in the thoracic spine. CONCLUSIONS: ldCT, covering the whole spine, detects more progression in the form of new and growing syndesmophytes in patients with AS compared with CR, which is limited to the cervical and lumbar spine. Most progression occurred in the thoracic spine.

Development of the CT Syndesmophyte Score (CTSS) in patients with ankylosing spondylitis: data from the SIAS cohort.

OBJECTIVES: To develop the CT Syndesmophyte Score (CTSS) for low-dose CT (ldCT) to assess structural damage in the spine of patients with ankylosing spondylitis (AS) and test its reliability. METHODS: Patientswith AS in the SIAS cohort had whole spine ldCT at baseline and 2 years. Syndesmophytes were scored in coronal and sagittal planes in eight quadrants per vertebral unit (VU) as absent=0, <50% of the intervertebral disc space (IDS)=1, ≥50%=2 or bridging the IDS=3 (range 0-552). Images were scored by two readers, paired by patient, blinded to time order. Whole spine and spinal segment status and change scores were calculated. Inter-reader reliability was assessed by intraclass correlation coefficient (ICC), smallest detectable change (SDC) and frequency of scores per VU. RESULTS: 49 patients (mean age 50 years (SD 9.8), 84% men, 88% human leucocyte antigen B27 positive) were included. Mean (SD) scores of reader 1 were: whole spine baseline status score 163 (126) and change score 16 (21), spinal segment baseline status scores 30 (41), 97 (77) and 36 (36) and change scores 2 (7), 12 (18) and 3 (4) for the cervical, thoracic and lumbar spine, respectively. Scores of reader 2 were similar. Whole spine status score ICC was 0.99 and 0.97-0.98 for spinal segments. Whole spine change score ICC was 0.77 and 0.32-0.75 for spinal segments. Whole-spine SDC was 14.4. Score distribution pattern per VU was similar between readers. CONCLUSIONS: Using the CTSS, new bone formation in the spine of patients with AS can be assessed reliably. Most progression was seen in the thoracic spine.

Prevalence of degenerative changes of the spine on magnetic resonance images and radiographs in patients aged 16-45 years with chronic back pain of short duration in the Spondyloarthritis Caught Early (SPACE) cohort.

OBJECTIVES: To determine the prevalence of degenerative changes (DCs) in the spine of young patients with back pain without axial spondyloarthritis (no-axSpA), with possible axSpA (poss-axSpA) and with definite axSpA (axSpA), as shown on MRI and radiographs. METHODS: Whole-spine MRI and cervical and lumbar radiography were performed in patients ≥16 years of age with chronic back pain (≥3 months, ≤2 years, onset <45 years) and potential axSpA (Spondyloarthritis Caught Early cohort). Patients were classified as no-axSpA, poss-axSpA [not fulfilling the Assessment of Spondyloarthritis International Society (ASAS) axSpA criteria] or axSpA (fulfilling ASAS axSpA criteria). Images (MRI and X-rays) were evaluated on the presence of DCs by two independent readers, blinded to clinical and laboratory information as well as to the results of the other imaging modality. In cases of disagreement, a third reader served as adjudicator. A Chi-square test was used to analyse differences between patient groups according to various selected cut-off points (1-3) of individual DCs. RESULTS: Of 274 patients (38% male, mean age: 29 years), 25 (9%) were classified as no-axSpA, 134 (48.9%) as poss-axSpA and 115 (42.0%) as axSpA. Two hundred and forty-five (89%) patients had DCs on MRI [21/25 (84%) no-axSpA, 121/134 (90%) poss-axSpA, 103/115 (90%) axSpA, P = 0.792], range 1-29 (median 5.5), and 121 (44%) patients had DCs on radiographs [13/25 (52%) no-axSpA, 62/134 (46%) poss-axSpA, 48/115 (42%) axSpA, P = 0.261], range 1-11 (median 2). Prevalence of DCs was similar between patient groups. DCs were predominantly found in the lumbar spine. CONCLUSION: Prevalence of DCs was high in this cohort of young patients with short-term chronic back pain, in accordance with the literature. Prevalence of DCs in no-axSpA patients, poss-axSpA patients and axSpA patients was found to be similar.

Prevalence of degenerative changes and overlap with spondyloarthritis-associated lesions in the spine of patients from the DESIR cohort.

OBJECTIVES: To describe the prevalence of degenerative changes on MRI and conventional radiographs of the spine in a young population with suspicion of axial spondyloarthritis (axSpA) and assess whether it is possible to discriminate between degenerative changes and lesions associated with axSpA. METHODS: Whole spine MRI and cervical and lumbar radiographs of patients ≥18 years with chronic back pain (≥3 months, ≤3 years, onset <50 years) were assessed for degeneration by two readers, and for SpA lesions by two other readers, all blinded for clinical information and results of the other readers. Degenerative scores were adjudicated in case of disagreement (by a third reader). Patients fulfilling and not fulfilling the Assessment of SpondyloArthritis international Society axSpA criteria were compared for prevalence of degenerative lesions. Scores for degenerative and SpA lesions were compared, and overlap was defined as the presence of both types of lesions in a single vertebral unit (VU). RESULTS: In 456/648 (70.4%) patients (46.8% men, mean age 33.6), degenerative lesions were found with similar percentages in patients with no axSpA and with axSpA (72.4% and 69.2%, p=0.45). Modic changes were found more often in patients with no axSpA (29/239, 12.1%) versus patients with axSpA (19/409, 4.6%, p=0.01). Other lesions were evenly distributed. Overlap was minimal in 19 patients (3.0%) and 32/14 674 (0.2%) VUs for SpA reader 1 and in 23 patients (3.6%) and 34/14 674 VUs (0.2%) for SpA reader 2. CONCLUSION: The prevalence of degeneration is high in an early inflammatory back pain cohort. Discrimination between degeneration and axSpA lesions is very well possible with little overlap between degenerative and axSpA readings.

Is the Site of Back Pain Related to the Location of Magnetic Resonance Imaging Lesions in Patients With Chronic Back Pain? Results From the Spondyloarthritis Caught Early Cohort.

OBJECTIVE: To determine associations between magnetic resonance imaging (MRI) lesions originating from either axial spondyloarthritis (SpA) or from degeneration and pain in patients with chronic back pain of <2 years duration. METHODS: Patients from the Spondyloarthritis Caught Early (SPACE) cohort identified the sites of pain (thoracic, lumbar, buttock). The average MRI scores from 2 readers for axial SpA lesions and from 2 different readers for degenerative lesions were used. Associations between sacroiliac (SI) joint lesions and buttock pain were investigated by logistic regression analysis, and associations between axial SpA or degenerative lesions and pain in the spine (thoracic and lumbar) were investigated using generalized estimating equations. Interactions with sex, age, HLA-B27, and fulfillment of Assessment of SpondyloArthritis international Society (ASAS) criteria were tested. RESULTS: In 348 patients (126 males, 127 fulfilling ASAS criteria, mean age 29.4 years), spinal MRI (and SI joint images in 342) were available. Pain was localized in the thoracic spine (35.9%), the lumbar spine (82.5%), or in the buttock(s) (57.8%). Inflammatory lesions of the SI joint (odds ratio [OR] 1.06; P = 0.04) and erosions of the SI joint in patients <25 years (OR 1.16; P = 0.04) were associated with buttock pain. Axial SpA spinal lesions were not associated with pain. Modic type 1 lesions in patients >35 years (OR 5.19; P = 0.001), high-intensity zone lesions in females not fulfilling ASAS criteria (OR 5.09; P = 0.001), and herniation in various subgroups (OR range 2.07-4.66) were associated with pain. CONCLUSION: Specific degenerative lesions, but not typical axial SpA lesions, of the spine are associated with pain at the same location in some subgroups. Inflammatory lesions in the SI joint are associated with buttock pain.