眼外肌病变的MRI表现

MRI Diagnosis of Orbital Diseases in Extraocular Muscles

目的探讨眼外肌病变的MRI表现,提高对其诊断和鉴别诊断的能力。资料与方法回顾性分析151例眶部疾病累及眼外肌患者的MRI表现。结果129例病变仅累及眼外肌肌腹（其中Graves眼病123例）,22例病变同时累及肌腱和肌腹（其中非特异性眶部肌炎7例,无Graves眼病病例）。77.8%的非特异性眶部肌炎仅累及单块肌肉,88.6%的Graves眼病是多块肌肉受累,眶部淋巴瘤、炎性假瘤和蜂窝织炎均是多肌肉受累。大多数Graves眼病及非特异性眶部肌炎均表现为中等程度大小、长形、边缘清楚的眼外肌病变,而肿瘤侵犯、眶部炎性假瘤和蜂窝织炎所致眼外肌病变则表现为不规则形、边缘不清。39例慢性期Graves眼病所致的眼外肌病变发生脂肪变性。61例急性期Graves眼病在T2WI上增粗的眼外肌表现为高信号,其T2值延长,均值为123ms（100-174ms）。结论眼外肌病变的位置、形态及其信号特征在MRI诊断和鉴别诊断中起重要作用。

Objective To discuss MRI features of orbital diseases in extraocular muscles and to improve accuracy of diagnosis and differential diagnosis. Materials and Methods MRI findings of 151 patients with extraocular muscles disease identified pathologically and clinically were retrospectively analyzed. Results Among 151 cases, 129 patients had involvement of muscles belly, including 123 cases of Graves＇ disease. 22 cases had involvement of both muscles belly and tendon, including 7 cases of orbital myositis, however, all of 123 cases with Graves disease never had involvement of muscles tendon. 77.8 % of orbital myositis involved single muscle, whereas 88.6 % of Graves disease and most lymphoma and phlegmon had multi-muscle involvement. Most Graves disease and orbital myositis had slight to moderate enlargement of involved muscles with long shape and clear margin. While involved muscles due to involvement of tumor, pseudotumor and phlegmon had irregular and poorly defined muscle outlines. 39 cases of Graves＇ disease with fatty degeneration had a partly hyperintensity signal on T1-weighted imaging in chronic stage. 61 cases of Graves＇ disease with active edema had hyperintensity signal on T2-weighted imaging with a mean value for T2 relaxation times of 123ms （ range, 100- 174 ms） in acute stage. Conclusions Location, morphological and MRI signal intensity of extraocular muscles diseases are very important for the differential diagnosis of the extraocular muscles disease.