CT of the pulmonary hilum.

Histologic examination of the lymph nodes is the only 100% accurate method of detecting metastatic disease. Even the pathologist encountering a lymph node cannot predict from the macroscopic appearance whether a lymph node is involved with tumor. Because enlarged lymph nodes may be free of tumor, and nodes of normal size may contain metastases, the accuracy of CT in the detection of hilar involvement by tumor is limited. The primary role of imaging procedures in the preoperative staging of patients with bronchogenic carcinoma is to determine the need for further prethoracotomy assessment. Decisions regarding operability of lung cancer should be based on tissue verification. Recognition of hilar abnormality requires a thorough understanding of normal bronchial and pulmonary vascular anatomy. The administration of intravenous contrast material can facilitate the distinction on a CT scan image of enhancing pulmonary vessels from nonenhancing hilar lymph nodes.