Role of vertebral corner inflammation and fat deposition on MRI on syndesmophyte development detected on whole spine low-dose CT scan in radiographic axial spondyloarthritis

Abstract

ObjectivesTo investigate the associations between MRI detected vertebral corner inflammation (VCI) and vertebral corner fat deposition (VCFD) on whole spine low-dose CT scan (ldCT) detected syndesmophyte formation and growth.MethodsPatients from the Sensitive Imaging in Ankylosing Spondylitis cohort underwent MRI (baseline, 1 year and 2 years) and ldCT (baseline and 2 years). MR images were scored by three readers for VCI and VCFD, MRI patterns were defined by presence of VCI and/or VCFD over 2 years. LdCT images were scored by two central readers for presence and size of syndesmophytes and change was calculated for new or new/grown syndesmophytes. Multilevel generalised estimated equations were used to test the associations between VCI and VCFD and syndesmophyte development.ResultsFifty radiographic patients with axial spondyloarthritis were included (mean age 49 years, 86% male, 78% HLA-B27+). Absence of both VCI and VCFD protected against syndesmophyte development (ORs 0.36–0.37). Presence of VCI and/or VCFD increased the risk of syndesmophyte development (ORs 1.73–2.60). Out of all corners with a new or new/grown syndesmophyte, 47% of corners according to reader 1 and 44% according to reader 2 had neither VCI nor VCFD preceding the bone formation.ConclusionsVCI and VCFD were positively associated with syndesmophyte development. This has been shown for the first time for syndesmophytes detected on ldCT and also in the thoracic spine. However, almost half of all bone formation occurred in corners without VCI or VCFD, suggesting the presence of these lesions in yearly MRIs does not fully clarify the development of syndesmophytes.

Inflammation, bone loss and 2-year bone formation at the same vertebra in axial spondyloarthritis: a multilevel MRI and low-dose CT analysis

“…Similar results have already been shown at the vertebral unit level in studies using radiographs, 24 32 but also using ldCT scans in the SIAS cohort. 31 Since no effect of inflammation-driven bone loss on subsequent bone formation was shown in our study, taken together, these results suggest a solid independent direct effect of inflammation on bone formation. In this scenario, trabecular bone loss and peripheral bone formation may coexist as a consequence of inflammation at the same vertebra.…”

“…However, these results should be interpreted with extreme caution due to relevant pitfalls: only few vertebrae were included, trabecular bone density variation throughout the spine was not accounted for, 28 30 and the analyses were not adjusted for local vertebral inflammation, a known relevant confounder for this relationship. 31 Though out of the scope of our research questions, when included as a confounder, the presence of MRI-BME at baseline was associated with a nearly twofold higher probability of 2-year syndesmophyte formation or growth, with this association persisting in multivariable analysis. Similar results have already been shown at the vertebral unit level in studies using radiographs, 24 32 but also using ldCT scans in the SIAS cohort.…”

“…However, these results should be interpreted with extreme caution due to relevant pitfalls: only few vertebrae were included, trabecular bone density variation throughout the spine was not accounted for, 28 30 and the analyses were not adjusted for local vertebral inflammation, a known relevant confounder for this relationship. 31 …”

Computed tomography-based assessment of radiographic progression in spine and sacroiliac joints after pregnancy in women with radiographic axial spondyloarthritis

“…A recent study showed that vertebral corner inflammation and vertebral corner fat deposition were positively associated with syndesmophyte development. However, almost half of bone formation occurred in corners without vertebral corner inflammation/fat deposition, suggesting the presence of these MRI lesions does not fully clarify the development of syndesmophytes, and low dose CT can be a useful tool for monitoring bone formation of whole spine in research ( 38 ). Third, the retrospective design of this study is a shortcoming.…”

Significance of structural changes in the axial skeleton in patients with axial spondyloarthritis: how important are lesions in the sacroiliac joint?

“…47 The important issue of replacing CR by low-dose CT in detail is beyond the scope of this editorial-even though there is increasing evidence that it does capture the whole spine (in contrast to CR and scoring with the mSASSS) and it is more sensitive to change. 21 What about the consequences of structural changes related to function and mobility? There is evidence that both, inflammation and structural changes in the spine, have an impact on function and mobility.…”