支气管肺癌的影像诊断

肺癌的主要影像检查方法为X线胸片、CT、MRI等，其中高电压胸片、高分辨CT是早期发现及鉴别诊断的最重要的方法。螺旋CT的影像重建技术和MRI对于肿瘤的分期有重要价值。中央型肺癌的早期X线表现为支气管的阻塞性改变，HRCT显示支气管狭窄、管壁增厚及管腔结节。周围型肺癌的早期X线表现为肺内结节或小斑片阴影，HRCT显示结节有分叶、空泡或细支气管气像、边缘毛糙及胸膜凹陷征。CT或MRI增强扫描显示肿瘤明显强化。经皮肺穿刺活检是诊断肺癌的重要方法。螺旋CT对于病变的多平面重建、三维重建及仿真支气管内镜可从多个角度显示病变的形态，对病变的鉴别诊断起辅助作用。对于肺癌转移的诊断方面，CT及MRI可较准确地判断淋巴结转移，三维CT血管重建（CAT）及MR血管成像（MRA）可准确地诊断肿瘤对血管的侵犯。MRI是确定胸壁转移的可靠方法。中心型肺癌需与肺结核及慢性肺炎鉴别，周围型肺癌应与结核球、慢性炎性结节等肺内孤立结节病变鉴别。在充分发挥X线胸片及HRCT检查的基础上，有目的地选择其他影像方法进行综合影像诊断，可提高肺癌的早期诊断及鉴别诊断水平。

Imaging Diagnosis of Bronchogenic Carcinoma

The X-ray film,CT and MRI are main diagnostic modalities for bronchogenic cancer.The high-voltage film and high resolution CT(HRCT)are important to the early and differential diagnosis of pulmonary cancer.The MRI and reformatted images from spiral HRCT are valuable to the tumor staging.The early appearances of central pulmonary cancer are stenosis of bronchus,thickening of bronchial wall,nodules in bronchus and air-way obstructive changes. The early peripheral pulmonary cancer often appears as a small nodule or patchy shadow on X-ray film.HRCT usually reveals it as the lobulated nodule,air-bronchogram,marginal spiculae and pleural indentation.In addition,contrast enhanced CT or MRI can provide more diagnostic information.Percutaneous pulmonary biopsy is an important diagnostic procedure.The multiplanar reconstruction,3D reconstruction and virtual bronchoendoscopy of spiral CT can demonstrate lesions in various aspects,and hence play additional roles in the diagnosis of bronchogenic cancer.For tumor metastasis,CT and MRI can show the involvement of lymph nodes and 3D CT angiography and MRI angiography can accurately reveal the involvement of great vessels.MRI plays a primary role in the diagnosis of chest wall invasion.The central pulmonary cancer should be differentiated from tuberculosis and chronic pneumonia.The periphery pulmonaral cancer should be differentiated from tuberculoma,chronic pneumonia and other solitary nodular lesions.If we make the most of the chest radiography and chest CT,and selectively use other imaging techniques,the accuracy of early diagnosis and differential diagnosis will be remarkably improved.