黏液性脂肪肉瘤的CT、MRI表现

CT and MRI features of myxoid liposarcoma

目的探讨黏液性脂肪肉瘤的CT、MRI表现特征。方法回顾性分析经手术病理证实的24例黏液性脂肪肉瘤的CT、MRI表现特点。18例术前接受CT平扫,其中9例同时接受增强扫描;6例接受MR平扫,其中5例同时接受增强检查。结果 24例黏液性脂肪肉瘤均表现为单发结节或肿块;发生于下肢(n=12)尤其大腿(n=9)最为多见,其次是腹膜后(n=7);发生于四肢的14例患者中,病变位于肌间隙10例(n=10),肌肉内2例(n=2),皮下脂肪层内2例(n=2);15例肿瘤形态规则,边界尚清,9例形态不规则,边界不光整,可见分叶等征象;病灶最大径2.0～38.0cm,平均(12.5±8.0)cm。18例CT平扫CT值11.0～30.0HU,平均(19.4±6.8)HU;6例MR平扫T1WI病变与肌肉相比以等或稍低信号为主,2例内见云絮状高信号;4例T2WI病变与皮下脂肪相比以明显高信号为主,内有稍高信号区和(或)线样低信号分隔,2例呈均匀显著高信号;14例CT和MR增强后病变均表现为明显不均匀强化;CT强化最显著区CT值35.0～112.0HU,平均(62.7±27.0)HU。结论黏液性脂肪肉瘤的CT、MRI表现有一定特征,CT平扫多为囊样低密度影,MRI以T1WI低信号、T2WI显著高信号为主,T2WI可伴稍高信号区和(或)线样低信号分隔,增强后多呈显著不均匀强化。

Objective To investigate the CT and MRI features of myxoid liposarcoma. Methods CT and MRI manifesta- tions of 24 patients with myxoid liposarcoma confirmed with pathology were reviewed retrospectively. Eighteen patients un- derwent plain CT, and 9 of them also underwent contrast-enhanced CT scan. Six patients underwent plain MR, and 5 of them also underwent contrast-enhanced scan. Results All [e^ions appeared as unilateral nodule or mass. Twelve tumors occurred in the lower extremity （n= 12）, particularly in the thigh （n= 9）, and then in the retroperitoneum （n= 7）. Among 14 extremity tumors, 10 occurred in the intermuscular fascial planes or deep-seated areas, 2 in the muscles and 2 in the sub- cutaneous tissues. The lesions appeared regular in 15 patients with well-defined margins, while irregular in 9 patients with ill-defined margins. The mean maximum diameter of the lesions was （12.5±8.0）em （ranged from 2.0 to 38.0 cm）. The average CT value of the lesions was （19.4±6.8）HU （ranged from 11.0 to 30.0 HU） on plain CT images. On T1WI, all 6 tumors showed predominant isointense or slightly hypointense signals relative to muscles, with 2 having amorphous loci of high signal intensity. On T2WI, the major portion of tumors in 4 patients displayed hyperintense signals compared with fat with slightly hyperintense areas and （or） linear hypointense signals, and the tumors in 2 patients showed remarkable homogeneous hyperintense signals. Fourteen tumors showed intense heterogeneous contrast enhancement. The average CT value of the intense enhanced-areas in the tumors was （62.7 ±27.0）HU （ranged from 35.0 to 112.0 H U） on enhanced CT images. Conclusion CT and MRI features of myxoid liposarcoma are distinctive to some extent, including predominant low attenuation on CT images, low signal intensity on T1WI, marked high signal intensity on T2WI with slightly hyperintense areas and （or） linear hypointense signals, as well as intense heterogeneous enhancement.