Quantification Evaluation of ^99mTc-MDP concentration in the lumbar spine with SPECT/CT: compare with bone mineral density

Background: Despite recent technological advances allowing for quantitative single-photon emission computed tomography (SPECT), quantitative SPECT has not been widely used in the clinical practice of osteoporosis. The aim of this study is to evaluate the feasibility of quantitative bone SPECT/CT for measuring lumbar standard uptake value (SUV) in patients with different bone mineral density (BMD), and investigate the correlation between SUV measured with ^99mTc-methylene diphosphonate(MDP) SPECT/CT and BMD assessment by dual-energy X-ray absorptiometry(DXA).

Methods: A retrospective analysis of 62 cases ^99mTc-MDP whole body bone imaging and local lumbar SPECT/CT tomography were performed. According to the results of dual energy x-ray bone density examination, they were divided into normal group, osteopenic group and osteoporosis group. The raw SPECT data were reconstructed using flash3D which includes attenuation correction, scatter compensation and collimator resolution recovery, SPECT images from this algorithm were calibrated for SUV analysis. Comparing difference of lumbar SUV in different BMD subjects, and investigate the correlation between lumbar SUV and BMD. Data were analyzed by one-way ANOVA and Pearson regression analysis using SPSS 17.0 software. Results: The maximum SUV (SUVmax) and mean SUV (SUVmean) of L1-L4 vertebral in 62 subjects were 7.39±1.84 and 4.90±1.27, respectively. The average BMD was 0.85±0.15 (g/cm²), and the average CT value was 145.88±53.99 (HU).The SUVmax, SUVmean, BMD and CT values &#8203;&#8203;of the lumbar spine were statistically significant difference among the three groups (F=24.089, 30.501, 94.847, 30.241, all p <0.001), and the osteopenic group was significantly lower than the normal group (all p <0.001), the osteoporosis group was significantly lower than the normal group and the osteopenic group (all p< 0.001). Lumbar SUVmax, SUVmean and BMD were significantly negatively correlated with age (r=-0.328~-0.442, all p<0.05), and positively correlated with body weight and CT value (r=0.299~0.737, all p<0.05), but no significant correlation with height (r=0.006~0.175, all p>0.05). Lumbar SUVmax and SUVmean increased significantly with the increase of BMD (r=0.638, 0.632, p<0.001). Conclusion: The SUV of lumbar spine in ^99mTc -MDP bone SPECT/CT was significantly different among subjects with different BMD, and the SUV was positively correlated with BMD. These findings justify that quantitative bone SPECT/CT is an applicable tool for clinical quantification of bone metabolism in osteoporosis patients. 1