软组织脂肪瘤与分化良好型脂肪肉瘤的MRI鉴别

Differentiation of soft tissue lipoma from well-differentiated liposarcom on MRI

目的评价 MRI 征象在诊断软组织脂肪瘤和分化良好型脂肪肉瘤中的价值。方法回顾分析经病理证实的22例软组织脂肪瘤和8例分化良好型脂肪肉瘤患者的 MRI 资料,比较2类肿瘤在大小、脂肪成分所占比例、厚分隔、结节或片状非脂肪成分、边缘及强化情况方面的差异。结果脂肪瘤和分化良好型脂肪肉瘤的直径分别为(64±35)和(138±44)mm(t=4.263,P<0.01),脂肪成分所占比例分别为(94±6)%和(74±9)%(t=5.903,P<0.01)。3例脂肪瘤和所有分化良好型脂肪肉瘤有2个以上厚分隔(P<0.01);结节或片状非脂肪成分见于4例脂肪瘤和全部分化良好型脂肪肉瘤(P<0.01)。行抑脂增强扫描的15例脂肪瘤中,仅有4例显示轻到中度强化,而分化良好型脂肪肉瘤中1例呈中度强化,7例呈明显强化(P<0.01)。脂肪瘤全部边界清楚,分化良好型脂肪肉瘤1例边界不清(P>0.05)。结论 MRI 有助于鉴别软组织脂肪瘤和分化良好型脂肪肉瘤,与脂肪瘤相比,分化良好型脂肪肉瘤体积多较大,脂肪成分相对较少,多有2个以上的厚分隔以及结节和(或)片状非脂肪成分,且强化明显。

Objective To evaluate the value of magnetic resonance imaging features in differentiating soft tissue lipoma from well-differentiated liposarcoma. Methods MR images of 30 patients with histologically verified fat-containing tumors （22 lipomas and 8 well-differentiated liposarcomas） were retrospectively reviewed. Well-differentiated liposarcomas and benign lipomas were compared in terms of the size of the lesion, percentage of adipose component, number of thick septa, nodular and （or） patchy nonadipose component, contrast enhancement patterns and the margin characters of the lesion. Results The mean size of lipomas [ （64 ± 35 ） mm] was significantly smaller （ t = 4. 263 ,P 〈 0. 01 ） than that of well- differentiated liposarcomas [ （138 ± 44） mm ], and the mean percentage of adipose component of lipomas [ （94 ± 6 ） % ] was significantly larger （ t = 5. 903, P 〈 0. 01 ） than that of well-differentiated liposarcomas [ （74 ±9）% ]. Thelipomas with more than two thick septa（3/22） were significantly less （P 〈 0. 01 ）than well-differentiated liposarcomas with （8/8）, and lopomas with nodular and/ or patchy nonadipose components （4/22） were significantly less（ P 〈 0. 01 ） than well-differentiated liposarcomas with（ 8/8 ）. The degree of contrast enhancement in 15 lipomas（4/15 mild to moderate enhancement ） was significantly lower （ P 〈 0. 01 ） than that in well-differentiated liposarcomas （ 1/8 moderate and 7/8 strong enhancement ）. Conclusion MRI is helpful in distinguishing soft tissue lipoma and well-differentiated liposarcoma. Compared with lipoma, features that suggest well-differentiated liposarcoma include large lesion size, decreased percentage of fat composition, presence of more than two thick septa, presence of nodular and/or patchy nonadipose areas and strong enhancement.