Novel MRI-based score for assessment of bone density in operative spine patients

Abstract

Background

Good bone quality is key in avoiding a multitude of afflictions, including osteoporotic fragility fractures and poor outcomes after spine surgery. In patients undergoing instrumented spine fusion, bone quality often dictates screw pullout strength, insertional torque, and vertebral body loading properties. While dual-energy X-ray absorptiometry (DEXA) screening is the current method of assessing bone mineral density, the majority of patients do not have DEXA measurements available before undergoing surgical instrumentation.

Purpose

To create a simple magnetic resonance imaging (MRI)-based score to evaluate bone quality and evaluate the degree to which it correlates with conventional DEXA scores.

Study Design/Setting

Retrospective cohort.

Patient Sample

Patients ≥18 years of age undergoing spine surgery for degenerative conditions between 2013 and 2018.

Outcome Measures

Correlation of the vertebral bone quality (VBQ) score with DEXA T-scores, and association between VBQ score and presence of osteopenia/osteoporosis.

Methods

Using noncontrast T1-weighted MRIs of the lumbar spine, the novel VBQ score was calculated for each patient. DEXA T-scores of the femoral neck and total hip were obtained and were compared with patient VBQ scores using linear regression and Pearson's correlation.

Results

Among 68 patients included in this study, 37 were found to have osteopenia/osteoporosis (T-score < −1.0) based on DEXA. A greater VBQ score was significantly associated with the presence of osteopenia/osteoporosis with a predictive accuracy of 81%. VBQ scores correlated moderately with femoral neck T-scores, the lowest overall T-scores of each patient, and correlated fairly with total hip T-scores.

Conclusions

This is the first study to correlate the novel VBQ score obtained from MRIs with DEXA T-score. We found this score to be a significant predictor of healthy versus osteopenic/osteoporotic bone with an accuracy of 81%, and found that VBQ score was moderately correlated with femoral neck and overall lowest T-score.