Opportunistic MRI assessment of low bone mineral density in patients with inflammatory bowel disease

Inflammatory bowel diseases (IBDs) are associated with low bone mineral density (BMD), usually assessed by dual-energy X-ray absorptiometry (DXA). The Vertebral Bone Quality (VBQ) score, derived from spinal MRI, offers a potential opportunistic alternative for assessment. This study evaluated the association between VBQ score and BMD measured by DXA in patients with IBD.

IBD patients were systematically evaluated by spine MRI and DXA. Opportunistic T1-weighted MRI findings were evaluated with the VBQ score, and BMD was assessed by DXA. Primary endpoint was the association between VBQ score and the diagnosis of low BMD. Diagnostic performance was analyzed with receiver operating characteristic (ROC) curves. Factors associated with low BMD were assessed on multivariate analysis.

Among 302 patients (65% women; mean [SD] age 42 [13] years), 134 (44%) had low BMD (25% of them with osteoporosis), and 46% had bone fragility. The mean VBQ score was significantly higher in patients with low BMD than normal BMD (2.45 [0.60] vs. 2.24 [0.55], p < 0.01). Similar results were found for bone fragility. On multivariate analysis, only VBQ score was significantly associated with both low BMD (OR = 1.91 [95% CI 1.18-3.09]) and bone fragility (OR = 1.90 [1.18-3.06]). ROC curve analysis revealed moderate diagnostic performance of the VBQ score for identifying low BMD (area under the ROC curve (AUC) = 0.62 [95% CI 0.54-0.65]). A VBQ score > 3.1 was highly suggestive of low BMD.

The MRI-measured VBQ score was decreased in IBD patients with low BMD. The relatively low sensitivity of the VBQ score limits the use of opportunistic MRI in a large screening program, but its high specificity allows for detecting low BMD in a selected IBD population with high risk of bone fragility.