骨化性肌炎的MRI表现特点与演变

目的分析骨化性肌炎的MRI表现特点与演变规律，以提高其诊断和鉴别诊断的水平。方法对13例患者（男性4例，女性9例，年龄11～65岁，平均年龄39.69岁）经手术或穿刺组织病理学诊断证实为骨化性肌炎的共16例次MRI检查图像进行回顾性分析。结果早期（2～3周，4例次）为边界不清的T1WI中等偏高信号、T2WI高信号为主的软组织肿块；中期（1-12个月，11例次）：T1WI由不均匀中等偏高信号逐渐变为中低信号，T2WI以团块和分叶状不均匀中低信号为主，夹杂有片状高信号区的软组织肿块，周边有低信号带形成。1例次内见有出血和液一液平，周围的水肿带（T1WI低信号、T2WI高信号）变窄。晚期（1～2年，1例次）：肿块缩小，T1WI和BWI上以高信号为主，夹杂有条带状低信号影。结论骨化性肌炎MRI表现有一定的特点和变化规律．具有一定的特征性．提高对其MRI表现的认识有助于诊断和鉴别诊断．避免不必要的手术。

The manifestation and variation of MRI in myositis ossificans

Objective To analyze the manifestation and variation of interrelations in MRI with myositis ossifieans, and improve the ability of diagnosis and differential diagnosis. Methods The MRI in 16 examinations of 13 cases （male 4, female 9, aged 11 - 65 years, mean age 39.69 years） with myositis ossificans proved pathologically were reviewed retrospectively. Results On the early phase （2 - 3 weeks, 4 examinations）, the lesions demonstrated a soft mass with poor defined margin showed moderate signal intensity on T1 weighted imaging and high signal intensity on T2 weighted imaging; On the middle phase （1 - 12 months, 11 examinations）, the signal of lesions changed to lower than before on T1 and T2 weighted imaging, but the signal was heterogeneity, and the lesions became lobulated with surrounding lower signal zone on T2 weighted imaging. In one case, intralesional hematoma was found and demonstrated high signal on T1 and T2 weighted imaging and contained a fluid-fluid level. Surrounding muscle edema became narrowed. On the later phase（1 - 2 years, 1 examination）： the imaging of lesion mainly showed high density signal and entrapped with a band of low signal intensity. Conclusion The manifestation and variation of MRI in myositis ossificans have certain characteristics. Thus this understanding is helpful to improve diagnosis and differential diagnosis of myositis ossificans, and unnecessary operation might be avoided.