肌内黏液瘤的CT和MRI表现

CT and MRI Findings of Intramuscular Myxoma

目的探讨肌内黏液瘤的CT和MRI表现,以提高对该病的诊断水平。方法回顾性分析经手术病理证实的16例肌内黏液瘤的CT和MRI表现,其中男7例,女9例,年龄2~66岁,中位年龄47岁。对肿瘤的部位、大小、形态、边缘、信号或密度、强化方式及周围情况进行分析。结果 16例中位于四肢9例,盆部2例,胸壁2例,腹壁2例,肩部1例。最大径约2.1~11.4 cm,平均(5.1±2.3)cm。13例病灶形态规则、边界清晰,3例形态不规则、局部边界不清。6例CT平扫表现为低密度,3例周围软组织可见脂肪帽;3例CT增强扫描中,2例表现为边缘轻度环形强化,1例表现为边缘环形强化并内部结节状强化。9例病灶T_1WI表现为低信号,11例病灶T_2WI及T_2抑脂序列均表现为显著高信号;MRI增强扫描3例表现为边缘环形强化,其中2例伴分隔线状强化;1例表现为显著强化;6例不均匀轻中度强化,其中3例多期增强扫描可见渐进性强化。9例T_2抑脂系列病灶周围软组织可见水肿信号,5例T_1WI病灶周围软组织可见脂肪沉积信号。结论肌内黏液瘤的CT和MRI表现具有一定特异性,大块肌肉内类似囊样肿块,不均匀延迟强化、边缘环形强化或分隔线状强化,周围软组织伴脂肪沉积及灶周水肿,可提示肌内黏液瘤的诊断。

Objective To evaluate the CT and MRI features of intramuscular myxoma and improve the diagnosis of this disease.Methods The CT and MRI characteristics of 16 patients （7 males and 9 females;ages ranging from 2 to 66 years,median age 47 years） with pathologically proven intramuscular myxoma were retrospectively reviewed.CT and MRI were evaluated in relation to the following：location,size,morphology,margin,density or signal intensity,enhancement pattern and changes of adjacent muscle.Results Nine lesions were located in the extremities,2 lesions in gluteus,2 lesions in chest wall,2 lesions in abdominal wall and 1 lesion in the shoulder.The tumor diameter varied from 2.1 to 11.4 cm （average,5.1 ± 2.3 cm）.Thirteen of the tumors presented well-defined borders and regular contours,and three presented illdefined borders and irregular contours.Six masses showed low attenuation on unenhanced CT scans,and areas of low attenuating fat around the lesions could be seen in three cases.Two of the three masses demonstrated peripheral enhancement and 1 had peripheral enhancement with nodularity on enhanced CT scans.All 11 masses showed high signal intensity on T2WI and TIRM images,and 9 were hypointense on T1WI.On enhanced MR images,3 masses demonstrated peripheral enhancement,2 of which also showed linear internal enhancement;1 lesion demonstrated remarkable enhancement;6 masses demonstrated heterogeneous enhancement,3 of which showed gradual enhancement.MR imaging showed the presence of fat around the lesion in 5 cases and peritumoral edema in 9 cases.Conclusion Intramuscular myxoma shows several recognizable CT and MR features （intramuscular masses with a cystic-like CT and MRI appearances,the presence of fat or edema in the surrounding muscles,the characterization of peripheral and internal gradual enhancement） which suggest its diagnosis.