中央型肺癌树芽征的CT影像分析

目的 探讨中央型肺癌树芽征的出现率、形成机制及与病理类型的关系。方法 收集接受胸部64层螺旋CT扫描且经病理证实的中央型肺癌304例，分析树芽征的出现率、伴随征象、出现范围及与病理类型的关系，对出现树芽征的病例采用MPR及 MIP进行图像后处理。结果 304例中央型肺癌中树芽征的出现率为17.76%（54/304），其伴随征象为肺门区不规则结节或肿块影伴以远支气管阻塞性扩张及黏液栓塞，树芽征出现范围与阻塞支气管所属的肺叶肺段相一致，MPR及MIP示树芽征均位于阻塞肺组织次级肺小叶中央，且与阻塞支气管相连；54例伴树芽征的中央型肺癌中，鳞癌36例（36/54，66.67%），腺癌6例（6/54，11.11%），腺鳞癌6例（6/54，11.11%），小细胞肺癌6例（6/54，11.11%）；54例中因树芽征误诊为结核18例，误诊率33.33%（18/54）。结论 树芽征可出现于中央型肺癌引起的阻塞性改变中，其形成机制可能系近端支气管狭窄程度加重继发远端细支气管阻塞性扩张及黏液栓塞；中央型肺癌树芽征的出现率与病理类型的关系还有待探讨。

Analysis of tree-in-bud sign on CT in patients with central lung cancer

Objective To explore the occurrence rate, formation mechanism and the relationship with pathological types of tree-in-bud sign on CT in patients with central lung cancer. Methods Totally 304 patients of pathologically confirmed central lung cancer who underwent chest 64-slice spiral CT scan were retrospectively analyzed, and the occurrence rate, accompanying signs, appearing range of the tree-in-bud sign and the relationship with pathological types were observed. Data of patients with tree-in-bud sign were processed at the workstation and analyzed using MPR and MIP. Results The occurrence rate of tree-in-bud sign in 304 patients with central lung cancer was 17.76% (54/304). The accompanying signs included irregular nodule or mass in the hilar region with distal obstructive bronchiectasis and mucus plugs, and the distributing of tree-in-bud sign was consistent with the range of bronchial obstruction. MPR and MIP showed the buds located in the center of secondary pulmonary lobule of obstructive lung tissue and connected with the obstructive bronchus. Among 54 patients of central type lung cancer with tree-in-bud, squamous cell carcinoma was finally diagnosed in 36 (36/54, 66.67%), while adenocarcinoma, adenosquamous carcinoma and small cell lung cancer were proved each in 6 patients (6/54, 11.11%), respectively. Eighteen patients with tree-in-bud sign were misdiagnosed as tuberculosis patients with central lung cancer. Conclusion Tree-in-bud sign usually can be seen as one of bronchial obstructive changes in central type lung cancer, its pathological basis may be bronchiolar obstructive dilatation and mucus filling because of proximal bronchial obstruction caused by distal bronchiolar involvement. Further exploration is necessary for the relationship between incidence of tree-in-bud sign and pathological types of central lung cancers.