Focal lung disease: CT and high-resolution CT applications.

Computed tomography (CT) and high-resolution CT (HRCT) play a central and important role in the evaluation and diagnosis of focal lung disease. Patients with known focal lung disease are usually best evaluated with CT of the entire thorax to exclude additional focal lung disease and to study the hilum and mediastinum. HRCT has superior spatial resolution, so that fine morphologic detail of lung disease can be better demonstrated. Care should be taken to select the patients most likely to benefit from CT or HRCT after appropriate evaluation with conventional modalities and comparison of the findings with those from previously obtained radiographs. CT or, when indicated, HRCT may obviate surgery or observation when the findings are diagnostic or may help in the selection of the most appropriate biopsy modality when the findings are indeterminate. If the findings are indeterminate after CT, HRCT may be helpful and cost-effective for diagnosis of focal infiltrative or nodular lung disease or abnormalities of the airways.