影像诊断与介入放射学

目的探讨双能量CT(DECT)虚拟去钙技术(VNCa)对膝关节隐匿性骨折的诊断价值。方法前瞻性收集有明确外伤史及膝关节活动障碍等症状、且临床诊断为膝关节隐匿性骨折的病例40例,同一天行膝关节DECT和MRI平扫检查。将每个膝关节分成12个区域(胫骨近端及股骨远端分别被分成6个区域),由两名独立的放射科医师评估膝关节VNCa图像是否存在骨髓损伤,在冠状位图像上测量正常区域和损伤区域VNCa图的CT值,并计算出两种CT值的差值。以MR图像作为"金标准",评估主观评价和CT差值对膝关节隐匿性骨折的检测能力。通过ROC曲线观察两种方法对膝关节骨髓损伤评价的敏感度和特异度。使用Kappa值来检验两位放射医师对膝关节骨髓损伤诊断的一致性。结果 40个膝关节共480个区域,MRI显示股骨远端和胫骨近端分别有74个和166个区域出现骨髓损伤。虚拟去钙图显示股骨远端和胫骨近端分别有77和171个区域出现骨髓损伤。VNCa图CT差值显示股骨远端和胫骨近端分别有76和174个区域出现骨髓损伤。VNCa图对膝关节骨髓损伤主观评价及CT差值客观客观评价分别与MRI成像的一致性较高(Kappa值分别为0.829和0.867)。主观评价及CT差值客观评价的曲线下面积(AUC)、敏感度、特异度、准确度分别为0.876和0.885、92.0%和95.6%、92.2%和95.2%、84.2%和90.8%。结论双能量CT虚拟去钙技术对于膝关节隐匿性骨折具有良好的诊断性能,与MRI有较高的一致性,为临床诊断隐匿性骨折提供了参考依据。

Objective To evaluate the diagnostic value of dual energy CT(DECT) with virtual noncalcium(VNCa) imaging in occult knee fractures. Methods Thirty patients with clinical suspicion of occult knee fracture based on history of trauma and knee movement disorder underwent DECT and MRI of the knee. Each knee was divided into 12 zones of distal femur(6) and proximal tibia(6). Two radiologists independently evaluated the VNCa images for the presence of bone marrow injury. On the coronal image,VNCa CT values of normal and injured bone marrow were measured, and the difference between the two CT values was calculated.MR images were used as the reference standard to evaluate the ability of subjective evaluation and CT difference to detect occult fractures of the knee joint. The sensitivity and specificity of the two methods for bone marrow injury were evaluated by receiver operating characteristic(ROC) curve. Kappa values were used to test the consistency of diagnosis of bone marrow injury by two radiologists. Results There were 480 zones in 40 knee joints. MRI showed bone marrow injury in 74 zones of the distal femur and166 zones of the proximal tibia. The VNCa diagram showed bone marrow injury in 77 zones of the distal femur and 171 zones of the proximal tibia. The VNCa difference showed bone marrow injury in 76 zones of the distal femur and 174 zones of the proximal tibia.The subjective evaluation(κ=0.829) and CT values(κ=0.867) in VNCa images were consistent with MRI. The area under the ROC curve(0.876), sensitivity(92.1%), specificity(89.3%) and accuracy(87.6%) of subjective evaluation were comparable to that of CT difference evaluation(0.885, 90.3%, 92.4%, 93.1%). Conclusion DECT and VNCa imaging has excellent diagnostic performance and high consistency with MRI for evaluating occult knee fractures. It can aid clinical diagnosis of occult fractures.