膝剥脱性骨软骨炎的X线平片与MRI诊断

The X-ray and MRI diagnosis of osteochondritis dissecans in the knee joint

目的 分析膝关节剥脱性骨软骨炎 (OCD)的X线平片与MRI表现 ,比较各序列对病变的检出价值。方法 对膝关节摄取平片 ,常规行冠状面和矢状面T1WI、质子密度加权像 (PDWI)、T2 WI、快速小角度激发 (FLASH)T 2 WI。选取资料齐全并已证实的OCD 36例 (38只 ) ,采用双盲对照的方法对X线及MRI征象进行分析 ;比较各序列对病变的检出率。结果 (1)病变好发于股骨内侧髁(2 4只 ,6 3.2 % ) ,典型型、扩展型和中心下面型分别占 5 5 .3% (2 1/ 38)、15 .8% (6 / 38)、2 8.9% (11/ 38)。(2 )其X线表现为从关节面剥离的小骨片 ,骨片密度较高 ,边缘锐利 ,周围环绕一圈明显的透亮线 ,其下为容纳骨片的骨窝。 (3)MRI表现为关节软骨下局灶性小病变 ,矢状面呈半月形 38例 ,冠状面呈楔形 14例、短条形 2 4例。病变在T1WI上呈低或等信号 ,在T2 WI、FLASHT 2 WI病变周边环绕一低或高信号带 ,软骨下骨板消失或变薄 ,部分可见关节软骨断裂或消失。 (4 )T1WI对病变的检出率较高。结论 (1)OCD有较独特的X线与MRI表现 ,MRI可对其作出较明确的诊断。 (2 )T1WI对病变的检出率较高。

Objective To investigate the X-ray and MRI manifestations of osteochondritis dissecans (OCD) and to compare the sensitivity of detection among different sequences. Methods Thirty-six OCD cases (thirty-eight knees) with complete data were selected and analyzed. The sagittal and coronal images were acquired on T 1WI, T 2WI, PDWI, and FLASH T * 2WI. MRI manifestations were analyzed retrospectively with double blind contrast method. The radiographies were obtained on the same day. The sensitivity of detection among different sequences was also compared. Results (1) The medial femoral condyle was the most commonly affected location in the knee (63.2%). The proportion of classical type, expanded type, and inferocentral type was 55.3%, 15.8%, and 28.9%, respectively. (2) On radiographs, the lesions typically appeared as a well circumscribed area of sclerotic subchondral bone separated from the remainder of the epiphysis by a radiolucent line. (3) Subchondral bone lesion was displayed as small and crescent-shaped ( n =38) on the sagittal image and as wedge (14) or short bar (24) shape on coronal image. The signal of the lesion was hypointense or isointense on T 1WI,surrounded by a hypointense or hyperintense (FLASH T * 2WI, T 2WI) line. The subchondral plate disappeared or became thinner. Interruption or disappearance of the hyaline cartilage could be seen sometimes. (4) The detection rate on T 1WI was higher than that of PDWI, T 2WI, and FLASH T * 2WI. Conclusion (1) Osteochondritis dissecans has specific X-ray and MRI manifestations. The abnormality of the hyaline cartilage and the subchondral bone can be displayed by MRI. Thus a proper diagnosis can be made. (2) The detection rate on T 1WI is higher than that of PDWI, T 2WI, and FLASH T  2WI.