[Evaluation of bone mass changes in patients with SAPHO syndrome by measuring bone mineral density on dual-energy X-ray absorptiometry and vertebral bone quality scores on MRI].

Objective

To explore bone mass changes in patients with SAPHO syndrome, utilizing bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) and vertebral bone quality (VBQ) scores measured by MRI.

Methods

Thirty-six patients with SAPHO syndrome at Peking Union Medical College Hospital from February 2014 to February 2024 were retrospectively collected with 36 age- and gender-matched healthy controls. DXA assessed BMD, corresponding T-score and Z-score of the lumbar spine (LS), femoral neck (FN), total hip (TH), and trabecular bone score (TBS). LS MRI T1-weighted imaging (T1WI) measured the VBQ scores. Correlations between BMD, TBS, and VBQ scores were analyzed using Pearson correlation. The predictive efficacy of VBQ scores for low bone mass and impaired bone microarchitecture in patients with SAPHO syndrome was assessed using receiver operating characteristic (ROC) curves, with the area under the curve (AUC), optimal diagnostic cut-off values, sensitivity, and specificity documented.

Results

The mean age of patients with SAPHO syndrome was (44.8±9.5) years, with 8 (22.2%) males. There were 36 subjects in the control group with a mean age of (44.8±9.5) years and 8(22.2%) males. Compared to the controls, the case group had lower FN BMD, TH BMD, corresponding T-score and Z-score, TBS, and higher VBQ scores (all P<0.05). Compared to the controls, female patients in the case group had lower LS BMD, FN BMD, TH BMD, corresponding T-score and Z-score, TBS, and higher VBQ scores (all P<0.05), whereas only male patients in the case group had higher VBQ scores (P=0.028). Ten cases (27.8%) in the case group had low bone mass and 19 cases (52.8%) had impaired bone microarchitecture, higher than the 3 cases (8.3%) and 9 cases (25.0%) in controls respectively (both P<0.05). VBQ scores in the case group were negatively correlated with FN BMD, FN T-score, TH BMD, TH T-score, and TBS (r=-0.375, -0.391, -0.368, -0.361, and -0.389, respectively, all P<0.05). The AUCs of VBQ scores for predicting ROC curves of low bone mass and impaired bone microarchitecture in patients with SAPHO syndrome were 0.796 (95%CI: 0.649-0.944) and 0.694 (95%CI: 0.521-0.866), with a sensitivity of 100.0% and 47.4%, and a specificity of 53.9% and 88.2%, respectively.

Conclusions

Patients with SAPHO syndrome present with low bone mass and impaired bone microarchitecture. VBQ score has a high sensitivity for predicting low bone mass and a high specificity for predicting impaired bone microarchitectural in patients with SAPHO syndrome.