249.Invasive aspergillosis（侵袭性曲霉菌病）

CT demonstration of a "halo sign" (ground-glass attenuation surrounding a nodule and representing hemorrhage) is suggestive of the diagnosis of angioinvasive aspergillosis in the right clinical setting.  About half of patients develop cavitation at a mean of 15 days after development of the infection, when the neutrophil count rises above 1000 cells/mm3.  The wall of the cavity is the site of angioinvasive aspergillosis.  The dependent soft tissue mass that forms within the developing cavity represents necrotic lung and may be partially surrounded by an "air crescent sign" in the non-dependent portion of the cavity.  In spite of the similar radiographic appearance, this is a completely different entity from mycetoma where there is fungal colonization in a preexistent cavity.  Hemoptysis may occur with the onset of cavitation. 

在 临床诊断中CT出现“晕环征”（结节周围磨玻璃密度影，表示出血）常提示侵袭性曲霉菌病。 半数患者在感染15天后病灶形成空洞，伴中性粒细胞计数升高1000以上。 空洞壁即侵袭性曲霉菌病的部位。 壁内的软组织肿块代表坏死的肺组织。 部分患者可在病灶偏心位置出现“半月空气征”。 该征象虽与“足分支菌病”相似，但病因却完全不同，其是因为真菌在先前存在的空洞中繁殖导致。 侵袭性曲霉菌病在空洞形成的开始可能会有咯血的症状。

Notes:

1. hemorrhage [ˈhɛmərɪdʒ] n.（尤指大量的）出血，失血; vi. 大出血

2. aspergillosis [ˌæspərdʒɪˈloʊsɪs] n. 曲霉病

3. crescent [ˈkrɛsənt] n. 新月，月牙;  adj. 新月形的

4. mycetoma [ˌmaɪsə'toʊmə] n. 足分支菌病

来源：每天朗读一段医学影像学英语文章