脂肪肝内转移瘤的影像学表现

目的评价脂肪肝内转移瘤的影像学表现及各种检查方法（重点为ＣＴ）的价值。方法脂肪肝内转移瘤９例,随诊３～１３个月临床证实。原发肿瘤为乳腺癌６例,卵巢癌、恶性黑色素瘤、结肠癌各１例。ＣＴ扫描９例１９次,Ｂ超扫描９例２０次。ＭＲＩ４例４次,血管造影２例６次。结果Ｂ超扫描２例次在中重度脂肪肝漏诊转移瘤。ＣＴ平扫根据肝密度低于脾,并低于、等于、高于肝内血管影,分为重度、中度、轻度脂肪肝。瘤灶分别呈高密度（重度）,高、等、低密度（中度）和低密度（轻度脂肪肝）。增强后,中、重度脂肪肝背景瘤灶均呈高密度。４例瘤灶密度不均。平扫４例瘤灶周围有２～６ｍｍ高密度晕环。ＭＲＩ的ＳＥ序列Ｔ１Ｗ为低信号,Ｔ２Ｗ为高信号,反相位（ｏｐｐｏｓｅｄ－ｐｈａｓｅ）为较高信号。结论脂肪肝内转移瘤的影像学表现较为复杂,与脂肪浸润程度密切相关。ＣＴ平扫时,中度脂肪肝因等密度易漏诊转移瘤。见有全周或半周较高密度环或密度不均者,应警惕肝转移瘤的可能,必须加作增强扫描以免漏诊。细致的ＭＲＩ检查有助于检出转移瘤。

Imaging manifestations of tumors metastasized in fatty liver

OBJECTIVE: To evaluate the manifestations of tumors metastasized in fatty liver and the value of various imaging modalities, especially CT. METHODS: Nine cases of tumors metastasized in fatty liver were proved by clinical follow-up for 3-13 months. The primary neoplasms were breast carcinoma in 6 cases; ovarian carcinoma, malignant melanoma and colon carcinoma, one case for each. All had CT(19 episodes) and ultrasonography (US, 20 episodes). Four cases had MRI and 2 cases had DSA. RESULTS: Liver metastatic lesions were missed by US in 2 cases with moderate to marked fatty liver. On CT without contrast administrations, fatty liver was divided into marked, moderate and mild degree according to the density of hepatic parenchyma which was lower than that of the spleen; lower and higher than or equal to that of the intrahepatic blood vessels. Depending on the degree of fat infiltration(FI), the density of the metastatic lesions was high when FI was marked and low when FI was mild. However, when FI was moderate, the density of the metastatic lesions varied, being high, equal or low. On enhanced CT, all of the lesions were enhanced with moderate to marked fatty liver background. Lesions were heterogeneous in 4 cases. On plain CT, metastatic lesions had high-density rim, 2-6 mm in width in 4 cases. In SE sequence of MRI, metastatic lesions were hypointense on T1W and hyperintense on T2W, and moderately hyperintense on opposed-phase. CONCLUSION: Tumors metastasized in fatty liver show a broad spectrum of image manifestations. They are related to the degree of fat infiltration. On plain CT, isodense lesions are easily escaped detection when moderate degree of fatty liver is present. Contrast administrations is mandatory. Liver metastases is suggested if a lesion is found with hyperattenuating rim on plain CT, or appears heterogeneous after enhancement. MRI is of diagnostic help.