Application of left femoral neck radioactive uptake ratio in ⁹⁹Tc^m-MDP bone scan for evaluation of osteoporosis

Objective: To evaluate the value of ⁹⁹Tc^m-MDP uptake by left femoral neck for diagnosing osteoporosis. Methods: A total of 58 cases (23 males, 35 females, mean age: (66.15±8.45) years) with spondyloarthropathies from May to December of 2012 were selected. Serum concentrations of type Ⅰ collagen telopeptide (sCTX-1) and bone ALP (BALP) were determined. All patients underwent dual-energy X-ray absorptiometry (DXA) to detect bone mineral density (BMD). According to the T scores,patients were divided into 2 groups:normal group (NG) (T>-1.0) and osteoporosis group (OG) (T≤-2.5). ⁹⁹Tc^mMDP bone scan was further performed. The average radioactive ratio of the left femoral neck to the medial soft tissue of left femur (T/N) was measured. Data differences between the 2 groups were compared by two-sample t test and Pearson correlation analysis. Results: According to BMD, 13 patients (7 males, 6 females) were included in NG and 28 patients (10 males, ¹⁸Females) were included in OG. The mean ages of OG and NG were significantly different ((68.82± 10.41) years vs (62.46± 11.77) years; t=3.560, P<0.05). The BMD of left femoral neck in OG was significantly lower than that in NG ((0.67±0.08) g/cm² vs (0.91±0.10) g/cm²; t=9.917, P<0.01). Although BALP level of OG was significantly higher than that of NG ((35.92±11.58) U/L vs (22.38±6.34) U/L; t=-3.397, P<0.05), no significant difference was observed on sCTX-1 between the 2 groups (t=-0.463, P>0.05). T/N ratio of OG (11.63±6.22) was higher than that of NG (9.74±4.44) (t=-3.027, P< 0.05). There were significant correlations between the T/N ratio of the left femoral neck and the sCTX-1 and BALP concentrations (r=0.376, 0.483, both P<0.01). No correlations between the T/N ratio of the left femoral neck and age, BMI and BMD were observed (r=-2.031, -0.017, 0.134, all P>0.05). Conclusion: The uptake ratio of the left femoral neck in ⁹⁹Tc^m-MDP bone scan could evaluate the metabolism of bone, and it is useful for the early diagnosis of osteoporosis. (authors)