磁共振成像在多发性肌炎、皮肌炎诊断中的应用

目的 研究多发性肌炎(PM)、皮肌炎(DM)的磁共振成像(MRI)表现，评价MRI在PM及DM诊断中应用价值。方法 对5例PM及4例DM患者行MRI检查，选择骨盆、双侧大腿及小腿肌肉，采用自旋回波序列(SE)、快速自旋回波序列(FSE)及短时反转恢复序列(STIR)进行扫描。结果 5例PM及4例DM患者的受累肌群均表现为斑片状等T1长T2异常信号，2例PM患者尚可见小斑片状短T1长T2异常信号影；6例患者肌筋膜增厚，呈长T2线样高信号改变；4例DM患者的表皮及皮下结缔组织尚可见条带状及网格状长T1长T2异常信号影。受累肌群主要表现为炎症水肿样改变，晚期受累肌肉可见少量脂肪替代改变；病变双侧不对称，以内收肌受累最重，股中间肌受累最轻。结论 PM与DM患者的MRI表现具有一定的特征性，MRI能为PM及DM的定位诊断、疗效判断及病情随访提供客观资料，并能为临床选取准确的活检部位提供帮助。

Magnetic resonance imaging in diagnosis of polymyositis and dermatomyositis

Objective To investigate the MRI features of polymyositis (PM) and dermatomyositis (DM),evaluate the clinical value of MRI for the diagnosis of PM and DM.Methods Five cases of polymyositis and four cases of dermatomyositis biopsy-proved underwent MRI of pelvis,thigh and calf.Spin echo sequence,fast spin echo sequence and short tau inversion recovery (STIR) were utilized.Results The signal intensity of diseased muscles of 9 patients with polymyositis and dermatomyositis was hyperintense on T_2-weighted images (T_2WI) and iso-hypointense on T_1-weighted images (T_1WI),and hyperintense signal intensity was also seen on T_2WI and T_1WI on 2 patients with polymyositis in late diseased duration.The thickened fascia was seen on 6 patients.The inflammatory intensity of involved skin and subcutaneous fat in 4 patients with dermatomyositis was found as band and meshy shaped.The involved muscles mainly show inflammatory and edematous findings asymmetrically,and fat replacement can be seen until late duration disease.Adductor muscles are the most severely affected and vastus intermedius is the least affected.Conclusion The MRI findings in PM and DM show certain characteristics,MRI might provide objective data for clinical localized diagnosis,therapeutic evaluation and follow-up.It might also help to decide the accurate localizations for biopsies.