膝关节隐匿性骨折的影像诊断分析

Occult fracture of the knee:detection with multimodality imaging

目的探讨多层螺旋CT(MSCT)三维重建及磁共振成像(MRI)在膝关节隐匿性骨折的诊断价值。方法连续选取30例CT三维重建或MRI诊断骨折而数字化X线摄影(DR)阴性的外伤患者的影像进行回顾性分析。30例行DR和MSCT三维重建检查,其中26例行MRI检查。结果 CT及MRI共显示隐匿性骨折43处,30例患者中MSCT漏诊7例,23例MSCT结合三维重建共显示骨折26处,26例MRI共显示骨折39处,MSCT漏诊7例为未累及骨皮质的骨内骨折,MRI表现为松质骨内T1WI线样低信号及T2WI低信号伴骨髓水肿。6例骨皮质隐匿性骨折MSCT检出骨皮质中断,MRI则未能明确显示骨折线,仅表现为骨折处皮质下T2WI模糊水肿高信号。结论 MRI显示膝关节隐匿性骨折及伴发骨髓水肿方面较CT更为敏感,尤其是骨内骨折;MSCT应用三维重建显示骨皮质骨折优于MRI,二者相互结合可减少膝关节隐匿性骨折的误、漏诊率。

Objective To investigate the value of MSCT three-dimensional reconstruction and MRI in diagnosis of occult fracture of the knee. Methods The imaging findings of 30 cases with CT or MRI showed knee traumatic fracture but DR-negative were analyzed retrospectively. Thirty cases were preformed standard DR and MSCT, and 26 cases undergone DR, MSCT and MRI. Results A total of 43 occult fractures of the knee in 30 patients were detected on CT and MRI. Seven of 30 cases were no evidence of fracture on MSCT, 26 fractures of the knee were showed on MSCT three-dimensional reconstruction in the other 23 cases. Thirty-nine fractures of the knee were detected on MRI.Seven cases with no fracture on MSCT were intraosseous fracture without involving the cortical bone, which showed streaky low signal intensity in cancellous bone on T1 weighted imaging and low signal intensity with bone marrow edema on T2 weighted imaging. Cortical bone fractures in 6 cases were showed on MSCT; whereas, there was not clearly showed fracture line on MRI. Conclusion MRI is more sensitive than CT in detecting occult fracture of the knee and concomitant bone marrow edema, especially intraosseous fracture; MSCT 3D- reconstruction is superior to MRI in displaying cortical bone fractures. Combined MRI with MSCT 3D-reconstruction could reduce the rate of misdiagnosis in occult fracture of the knee.