双能量CT虚拟去钙技术评价骨质疏松症的价值

目的 评估双能量CT（DECT）虚拟去钙（VNCa）技术定量评价骨质疏松症的应用价值。 方法 回顾性纳入55例慢性腰腿痛病人,其中男29例,女26例,平均年龄（49.8±12.1）岁。所有病人均行腰椎DECT扫描并采集定量CT（QCT）数据。通过修改双能量分析软件中虚拟平扫的配置文件,定量测量对比剂CT值（CM）、常规CT值（rCT）、钙浓度（CaD）及脂肪分数（FF）;利用QCT pro定量分析系统测量椎体的骨密度（BMD）。依据金标准BMD< 80 mg/cm³,将纳入的全部椎体（318个）分为骨质疏松组（OP,87个）和非骨质疏松组（NOP,231个）。采用组内相关系数（ICC）分析2名医师测量数据结果的一致性。采用独立样本t检验比较2组间DECT定量参数的差异。采用Pearson相关分析BMD与DECT定量参数的相关性,并建立多元线性回归模型,将由该模型计算得到的BMD表示为回归BMD（rBMD）,得出决定系数r²和rBMD的方程。以QCT的BMD值作为金标准,采用受试者操作特征（ROC）曲线评价rBMD、CM、CaD、FF的诊断效能。 结果 2名医生测量BMD和DECT定量参数的一致性较好（均ICC>0.75）。OP组的CM、rCT、CaD均低于NOP组,而FF高于NOP组（均P<0.05）。CM、rCT、CaD、FF值与BMD均具有相关性（r分别为0.885、0.947、0.877、-0.492,均P<0.05）。将CM、CaD、FF纳入回归模型计算得出:r²=0.915,rBMD=54.82-0.19×CM+20.03×CaD-1.24×FF。当rBMD的阈值为81.94 mg/cm³时诊断效能最高,其敏感度、特异度、AUC分别为90.04%、91.95%、0.966（0.940~0.983）。 结论 DECT的VNCa技术可作为一种BMD测量的补充方法,从骨矿物质及脂肪含量方面定量评价骨质疏松症。

The value of dual-energy CT virtual non-calcium technique in evaluation of osteoporosis

Objective To evaluate the value of dual-energy computed tomography (DECT) virtual non-calcium (VNCa) technique in quantifying osteoporosis. Methods A total of 55 patients with chronic low back pain were retrospectively enrolled, including 29 males and 26 females, with an average age of 49.8±12.1 years. EDCT scans were performed for them, and QCT data were collected. By modifying the configuration file of Virtual Non Contrast in dual energy analysis software, CT value of contrast media (CM), regular CT value (rCT), calcium density (CaD), and fat fraction (FF) were measured quantitatively. Bone mineral density (BMD) was measured using QCT pro quantitative analysis system. According to gold standard BMD<80 mg/cm³, all the 318 included vertebrae were divided into osteoporotic group (OP, 87) and non-osteoporotic group (NOP, 231). The intra group correlation coefficient (ICC) was used to analyze the consistency of the measured data of the two doctors. The differences in DECT quantitative parameters between groups were compared by independent sample t test. Pearson test was used to assess correlations between BMD and DECT quantitative parameters, and a multiple linear regression model was established. The BMD calculated by the model was expressed as regression BMD (rBMD). Taking the BMD value of QCT as the gold standard, the diagnostic efficacy of rBMD, CM, CaD, and FF were evaluated by subject operating characteristic (ROC) curve. Results The BMD value and DECT quantitative parameters measured by two doctors were consistent (all ICC>0.75). The CM, rCT, and CaD were lower in OP group than in NOP group, while the FF was higher than in NOP group (all P<0.05). The CM, rCT, CaD, and FF values significantly correlated with BMD (r values: 0.885, 0.947, 0.877, -0.492, respectively; all P<0.05). The CM, CaD, and FF were included in the regression model, and the equation of rBMD showed as follows: r²=0.915, r_BMD=54.82-0.19×CM+20.03×CaD-1.24×FF. At a rBMD threshold of 81.94 mg/cm³, the diagnostic efficiency was the highest, and the sensitivity, specificity and AUC were 90.04%, 91.95% and 0.966 (0.940-0.983), respectively. Conclusions DECT VNCa technique may constitute a valid alternative method for quantifying the mineral content and marrow fat composition of bone in diagnostic assessments of osteoporosis.