双源CT虚拟去钙技术在最优条件下测得CT值与膝关节隐匿性骨髓水肿程度的相关性分析

Analysis of correlation between the CT values measured by the third generation dual source virtual calcium removal technique and the degree of latent bone marrow edema of knee joint under optimal conditions

目的探讨第三代双源CT虚拟去钙(VNCa)图像在最优条件下测得CT值与膝关节隐匿性骨折局部骨髓水肿(BME)程度的相关性。方法选取30例膝关节隐匿性骨折患者,进行膝关节双源CT和MRI影像检查,每个膝关节分为12个区域(股骨下段及胫骨上段各6个),以MRI检查为标准,对不同相对钙比率条件下VNCa图进行分析,获取最优条件下测得CT值,分析CT值与膝关节隐匿性BME程度的相关性。结果30例患者行膝关节双源CT和MRI检查,360个区域全部进入结果分析,无脱落。MRI显示136个区域出现BME,63个在股骨下段,73个在胫骨上段,均表现为T1WI低信号与脂肪抑制PDWI(或T2WI)高信号。相对钙比率1.69与1.79对应的双源CT-VNCa图像均对BME诊断效能较高。相对钙比率1.79时双源CT-VNCa图像测量水肿面积与MRI测量面积同类相关系数为0.88,选取相对钙比率1.79为双源CT-VNCa图像诊断BME的最佳值。BME区域CT值高于正常区域CT值,差异有统计学意义(P<0.05);Spearman相关性、线性回归分析均显示膝关节隐匿性骨折BME患者相对钙比率1.79对应的双源CT-VNCa图像上BME区域CT值与BME程度显著相关(P<0.05)。结论相对钙比率1.79为第三代双源CT-VNCa技术测量CT值的最优条件,该条件下测得的CT值与膝关节隐匿性BME程度的密切相关。

Objective To investigate the correlation between the CT value of the third generation dual source virtual decalcification(VNCa)images under optimal conditions and the degree of occulted knee fracture BME.Methods Thirty patients with occulted fracture of knee joint in our hospital were selected for dual source CT and MRI examination of knee joint.Each knee joint was divided into 12 regions(with 6 in each of the lower femur and upper tibia segments).VNCa images under different relative calcium ratios were analyzed based on MRI examination.CT values were obtained under optimal conditions and the correlation between CT values and the degree of latent bone marrow edema of knee joint was analyzed.Results All 30 patients were included in the result analysis,undergoing knee joint dual-source CT and MRI imaging.All 360 regions were included in the result analysis,with no exclusions.MRI showed that 136 regions exhibited BME,with 63 in the lower segment of the femur and 73 in the upper segment of the tibia,all of which presented as low T1WI signals and high fat-suppressed PDWI(or T2WI)signals.The relative calcium ratios of 1.69 and 1.79 were associated with higher diagnostic efficacy for BME in dual-source CT-VNCa images.For the relative calcium ratio of 1.79,the correlation coefficient between the edema area measured by dual-source CT-VNCa images and the corresponding MRI measurement was 0.88.It was recommended to choose the relative calcium ratio of 1.79 as the optimal value for the diagnosis of BME by dual-source CT-VNCa images.The CT values of the BME regions were higher than those of the normal regions(P<0.05).Both Spearman correlation and linear regression analyses demonstrated a significant correlation between the CT values of the BME regions and the degree of BME in patients with latent fractures of the knee joint at the relative calcium ratio of 1.79 in dual-source CT-VNCa images(P<0.05).Conclusions The optimal condition for measuring CT values with the third-generation dual-source CT-VNCa technology is a relative calcium ratio of 1.79.Under this condition,the CT values measured are closely correlated with the degree of latent BME in the knee joint.