长径≤4cm乏脂肪型血管平滑肌脂肪瘤与肾透明细胞癌的CT鉴别

目的：提高对长径≤4cm的乏脂肪型血管平滑肌脂肪瘤（AML）和肾透明细胞癌的CT诊断准确性。方法：对长径≤4cm的14例（16个病灶）乏脂肪型AML和16例（16个病灶）肾透明细胞癌的CT形态学表现（楔形征、肿瘤位置、钙化、假包膜及瘤内血管）及平扫、增强CT值进行测量及分析，所有肿瘤均经手术病理证实。结果：两组中楔形征（P=0．023）、瘤内血管（P=0．029）、假包膜（P=0．023）、平扫CT值（P〈0．001）、皮髓质期及排泄期的绝对强化值（分别P=0．009和0．044）及相对强化幅度（分别P=0．008和0．020）的差异有统计学意义，其中两期的相对强化幅度的Pear—SOIl相关系数（r=0．461和=0．409）较绝对强化值（r=0．456和-0．366）高。而钙化（P=0．484）及肿瘤位置（P=0．473）在两组间的差异无统计学意义（P〉0．05）。排泄期CT相对强化幅度〉-19．2％时，诊断乏脂肪型AML的特异度及敏感度分别为87．5％和25．0％。结论：乏脂肪型AML中楔形征多见，瘤内血管、假包膜少见；其平扫CT值较透明细胞癌病灶高，与竖脊肌相似，皮髓质期相对强化幅度较透明细胞癌低，排泄期对比剂退出较少，其中肿瘤的CT相对强化幅度对诊断更有意义。

Value of CT in the differentiation between angiomyolipomas with minimal fat and clear cell renal cell carcinomas whose diame- ter less than 4cm

Objective：To study the differentiation between angiomyolipomas （AMLs） with minimal fat and clear cell renal cell carcinomas whose size all smaller than 4cm,according to their morphologic and CT enhancement features. Methods：The morphologie manifestations （wedge sign,location, calcification, pseudo capsule, and intra-tumoral vessels）, unenhanced CT value and enhanced CT value in 14 cases （16 lesions） of AMLs with minimal fat and 16 cases （16 lesions） of clear cell renal cell carcinomas with diameter ≤4cm, were statistically analyzed. All the lesions were confirmed pathologically. Results： For the AMLs group and clear cell renal cell carcinoma group, there was significant difference in wedge sign （P=0. 023） ,intra- tumoral vessel （P=0. 029）, pseudocapsule （P= 0. 023）, unenhanced CT value （P=0. 001） and the absolute/relative atte- nuation values of the two phase （cortico-medullary phase and exctretory phase） with P=0. 009,0.04,0. 008 and 0. 020 re- spectively, meanwhile the Pearson correlation eoefficient of the relative enhancement values （r= 0. 456 and -0. 366 respec- tively） of the two phase were higher than that of the absolute enhancement values （P=0. 456 and -0. 366 respectively）. While the difference of the calcification （P=0. 484） and location of the tumor （P=0. 473） had no statistical significance be- tween the two groups. The specificity and sensitivity were respectively 87.5 % and 25 % for diagnosing AML with minimal fat when the relative enhancement degree in the excretory phase〉- 19.2 %. Conclusion： Angiomyolipomas with minimal fat often showed wedge sign, though the intra-tumoral vessels and pseudocapsule rarely appeared. The unenhanced CT value was higher than that in clear cell renal cell carcinoma, similar to that of the erector spinae. Its enhancement level was lower than that of clear cell renal cell carcinoma in the corticomedullary phase, contrast washout was less than that in the clear re- nal cell carcinoma in the excretory phase.