Radiologic Evaluation in Chest Malignancies

A Review of Imaging Modalities

¹ From the Department of Radiology, Harvard Medical School, Boston

Radiologic evaluation of the patient with non-small cell lung cancer (NSCLC) includes chest radiographs for detecting nodules, computed tomography (CT) for further characterizing them, CT and magnetic resonance imaging (MRI) to evaluate the mediastinum, and extrathoracic imaging of bones, the adrenal gland, the central nervous system, and liver. The current practice standards for each are reviewed. Asymptomatic solitary pulmonary nodules, which are usually detected on chest radiographs obtained for other indications, inevitably require a precise diagnosis. The radiologic characteristics that differentiate benign from malignant pulmonary lesions are given. Mediastinal CT is the preferred modality for examining the mediastinum in patients with NSCLC. Magnetic resonance imaging is used selectively, eg, in patients with superior sulcus tumors who are candidates for surgery. When evaluation for N2/N3 disease is requested, mediastinoscopy should replace CT using the latter as a "roadmap." The role of extrathoracic imaging in evaluating asymptomatic patients with NSCLC at initial presentation is equivocal. Computed tomographic scanning of the head is reasonable in most patients with lung cancer, given the significant incidence of occult brain metastases in this population and that solitary brain lesions may be resected in some protocol settings. Routine liver and adrenal gland scanning is similarly controversial. Bone scans do not appear to be useful in patients with NSCLC unless they have clinical signs, symptoms, or laboratory findings to indicate possible metastases. Although heavily affected by local practice, radiologic evaluation of the patient with NSCLC should attempt to provide accurate determination of local disease and a search for distant metastases.