Quantitative measurement of standard uptake value of Lumbar vertebra in SPECT/CT ^99mTC-MDP bone imaging

Objectives: To explore the method of determining standard uptake value (SUV) of lumbar vertebra in SPECT/CT ^99mTC-methylene diphosphonate(^99mTC-MDP) bone imaging.

Methods: A retrospective analysis of 90 cases of ^99mTC-MDP bone scan and local lumbar SPECT/CT tomography was performed that using CT attenuation correction, scatter correction and 3-Dimensional ordered subset expectation maximization reconstruct image. The radioactivity of unit volume (kBq/cm³) was calculated based on the counts of the degenerative changes and bone metastases that with MDP high uptake and the L1-L4 vertebral that with non MDP high uptake subjects (osteoporosis and non osteoporosis), and convert it to a SUV value. The difference of SUV for lumbar and lesions from different types of subjects and the correlation with bone mineral content, CT value, age, weight and height were compared. The data were analyzed by independent sample t test and Pearson regression analysis using SPSS17.0 software.

Results: The mean SUV (SUVmean) and maximum SUV (SUVmax) of L1-L4 vertebral in 54 cases with non high MDP uptake were 4.64±1.03 and 7.09±1.61 respectively, It was positively correlated with bone mineral content, CT value and body weight (r=0.700 and 0.672,0.672 and 0.654,0.433 and 0.469, P all <0.05), and negatively correlated with age (r=-0.514 and -0.456, P all< 0.001), and no significant correlation with height (r=0.120 and 0.147, P all>0.05). The SUVmean and SUVmax of the subjects with osteoporosis were 3.81±0.76 and 5.86±1.34 respectively, which were significantly lower than those of non osteoporotic subjects (5.13±0.84 and 7.82±1.30 t=-5.892 and -5.240, P all<0.001). The SUVmean and SUVmax were 16.40±6.07 and 24.25±11.35 respectively in 16 patients with 37 metastases, which were significantly higher than that of degenerative changes (20 patients with 27 lesions) of 9.30±3.16 and 13.48 ±5.21 (t=6.074 and 5.083, P all< 0.001), and it was no significant difference in the muscles(0.21±0.09 and 0.19±0.08, 0.36±0.11 and 0.37±0.16,t=0.984 and -0.131 ,p all﹥0.05)

Conclusions: Based on the specific reconstruction algorithm and correction method, the standard uptake value of lumbar vertebra in SPECT/CT ^99mTC-MDP bone imaging can be obtained, and the bone salt metabolism state can be accurately reflected.