目的 以定量CT(QCT)测量胸腰椎椎体骨密度值为标准,验证双层探测器光谱CT能谱衰减曲线斜率评价椎体骨密度值的可行性。方法 收集2023-07至2023-12在解放军总医院海南医院放射诊断科行胸部CT检查的患者128例为研究对象,测量T11、T12及L1椎体骨松质QCT值,用40 keV及70 keV能级水平图像CT值的差值与能级水平差值的比值量化能谱衰减曲线;利用Person相关系数法分析患者QCT值及能谱衰减曲线斜率λ值一致性,绘制ROC曲线,分析能谱衰减曲线斜率诊断骨量减低及骨质疏松的效能。结果 T11、T12、L1椎体及总体QCT值的平均值分别为(137.66±34.01)、(132.74±31.62)、(126.72±31.38)及(132.27±32.35)mg/cm³;λ值的平均值分别为(6.71±1.57)、(6.37±1.63)、(6.27±1.54)及(6.45±1.59)Hu/kev;T11、T12、L1椎体及总体QCT值与λ值相关系数r值分别为0.931、0.943、0.943及0.938,均具有优异的一致性,差异有统计学意义(P＜0.05);T11、T12及L1椎体男性组QCT值均高于女性组,T12及L1椎体男性组λ值高于女性组,差异有统计学意义(P＜0.05);T11、T12及L1椎体中年组QCT值与λ值均高于老年组,差异有统计学意义(P＜0.05);以QCT值120 mg/cm³分组,λ值诊断椎体是否骨量减低时AUC值0.978,约登指数0.8678,λ值截断值5.90,此时敏感度92.13%,特异度94.66%;以QCT值80 mg/cm³分组,λ值诊断椎体是否为骨质疏松时AUC值0.965,约登指数0.8662,λ值截断值4.90,敏感度89.40%,特异度97.22%。结论 双层探测器光谱CT能谱衰减曲线斜率具有用于评价胸腰椎椎体骨密度值的潜力,在临床常规中具有可行性。

Objective To verify the feasibility of evaluating vertebral bone mineral density by using quantitative CT (QCT) to measure the bone mineral density (BMD) of thoracolumbar vertebrae, and the slope of spectral CT attenuation curve with double-layer detector. Methods A total of 128 patients who underwent chest CT examination in the Department of Radiology, Hainan Hospital of PLA General Hospital from July 2019 to December 2019 were collected, and the QCT values of bone cancelation in thoracic 11, thoracic 12 and lumbar 1 vertebrae were measured. The attenuation curve of energy spectrum was quantified by the ratio between the difference of CT values of 40 Kev and 70 Kev level images and the difference of energy level. Person correlation coefficient method was used to analyze the consistency of QCT value and λ value of slope of energy spectrum decay curve of patients, and ROC curve was drawn to analyze the efficacy of slope of energy spectrum decay curve in diagnosing bone mass loss and osteoporosis. Results The average QCT values in thoracic 11,thoracic 12,lumbar 1 vertebra and the whole body were (137.66±34.01) (132.74±31.62) (126.72±31.38) and (132.27±32.35) mg/cm³, respectively, The average λ values were (6.71±1.57) (6.37±1.63) (6.27±1.54) and (6.45±1.59) Hu/kev, respectively. The correlation coefficient r values of thoracic 11, thoracic 12, lumbar 1 and the total QCT value and λ value were 0.931,0.943,0.943 and 0.938, respectively, with excellent consistency and statistical significance(P<0.05). The QCT value of thoracic 11,thoracic 12 and lumbar 1 vertebra in male groups was higher than that of female group, the λ value of thoracic 12 and lumbar 1 vertebra in male group was higher than that of female group, and the difference was statistically significant(P<0.05). The QCT value and λ value of thoracic 11,thoracic 12 and lumbar 1 vertebra in the middle age group were higher than those in the elderly group, and the difference was statistically significant(P<0.05). With QCT value of 120 mg/cm³, λ value of AUC value of 0.978, Jordon index of 0.8678, λ value of cutoff value of 5.90, sensitivity of 92.13%, specificity of 94.66% when diagnosing vertebrae with low bone mass. The patients were grouped with a QCT value of 80 mg/cm³. The ACU value was 0.965, the Jorden index was 0.8662, λ cutoff value was 4.90, sensitivity was 89.40%, and specificity was 97.22% when the vertebrae were diagnosed with osteoporosis. Conclusions The slope of spectral CT attenuation curve with double-layer detector has the potential to evaluate the BMD of thoracolumbar vertebrae, and is feasible in clinical practice.