目的：探讨黏液纤维肉瘤（MFS）的MRI表现及其病理基础，提高对本病的诊断水平。方法：回顾性分析16例经手术病理证实的MFS患者资料，就其MRI及病理进行总结分析；低度恶性组8例，中高度恶性组8例（中度恶性2例，高度恶性6例）。结果：14例位于浅筋膜下，2例位于肌间隙内；7例呈类圆形，6例呈梭形，3例呈不规则形，肿瘤最大径约4.6~13.2 cm，平均7.6 cm；MRI上，2例T1WI呈均匀稍高信号，14例呈混杂等/低信号，2例T2WI呈均匀高信号，14例呈混杂高信号，11例病变呈DWI混杂高信号，ADC均呈混杂低信号；10例增强扫描呈不均匀明显强化；15例可见“筋膜尾征”，12例见瘤周水肿，12例病灶内见“双低信号征”，11例见囊变、坏死，6例见黏液样变，其中6例囊变、坏死区及5例黏液样变区ADC值差异具有统计学意义（P＜0.05）；肿瘤大小、“双低信号征”及“尾征”于轻度恶性组、中高度恶性组之间差异无统计学意义（P＞0.05）。瘤周水肿、囊变坏死及黏液样变于两组间差异均有统计学意义（P＜0.05），且前两者多见于中高度恶性组，后者多见轻度恶性组；镜下疏松区富含黏液基质，并可见散在曲线形血管，细胞密集区见多发梭形肿瘤细胞，异型性明显，核分裂多见；免疫组化16例Vimemtin及13例CD34呈阳性。结论：MFS的MRI表现具有一定特征性，有助于术前诊断，最终确诊依赖病理。

Objective: To investigate MRI and relevant pathological features of myxofibrosarcoma(MFS). Methods: The MRI findings and pathological results of 16 cases with MFS proved by pathology were retrospectively analyzed. Eight cases were low-grade, 2 cases were intermediate-grade, and 6 cases were high-grade. Results: Fourteen cases were located under the superficial fascia, 2 cases were located in the muscular space, 7 cases were round shapes, 6 cases were spindle shapes, and 3 cases were irregular shapes. The tumors ranged from 4.6~13.2 cm in maximum diameter, with an average of 7.6 cm. On T1WI, 2 cases showed slightly hyper-intensity, 14 cases were heterogeneous with signal intensity similar or lower than that of muscles, 2 cases showed uniform high signal intensity on T2WI, 14 cases demonstrated mixed high signal intensity, 11 cases showed mixed high signal intensity on DWI and hypo-intensity signal on ADC, 10 cases presented heterogeneous enhancement. Fifteen cases showed “fascia tail signs”, 12 cases had peritumoral edema, 12 showed “double low signal signs”, 11 cases demonstrated cysts and necrosis, 6 cases showed mucoid degeneration. The difference of ADC value between 6 cases with cystic and necrotic and 5 cases with mucoid degeneration was statistically significant(P＜0.05). Tumor size, “double low signal signs” and “tail signs” were not significantly different between low-grade group and intermediate-high-grade group(P＞0.05). There were significant differences for peritumoral edema, cystic necrosis and mucoid degeneration between the two groups(P＜0.05). Microscopically, the mucoid matrix was rich in loose area with curved blood vessels around it. Multiple spindle tumor cells could be seen in dense areas of cells. The heterogeneity was obvious, and mitosis was more common. Immunohistochemically, all 16 cases were positive for vimentin, 13 cases were positive for CD34. Conclusion: MFS has certain MRI characteristics which is helpful to improve the diagnostic accuracy, the final diagnosis still depends on pathology.