Assessment of diffuse infiltrative lung disease: comparison of conventional CT and high-resolution CT

The diagnostic accuracies of conventional computed tomography (CT) and high-resolution CT (HRCT) in examination of the entire lungs were compared prospectively, and the diagnostic utility of a limited number of HRCT sections in the evaluation of diffuse infiltrative lung disease (DILD) was determined in 150 consecutive patients. Conventional 10-mm CT sections were equivalent to 1.2-mm HRCT sections in the recognition of nodules, masses, nodular irregularities of the interfaces, large cystic air spaces, and architectural distortion. Conventional CT was superior to HRCT in the diagnosis of micronodules and infiltrates. However, 15% of micronodules were recognized only on HRCT images because of their small size and low density. Fine bronchial and parenchymal lesions were best seen on HRCT scans. HRCT was the only technique that allowed assessment of the presence of areas of ground-glass attenuation. HRCT improves visualization of small parenchymal structures and allows a confident evaluation of DILD, providing that the entire lungs are studied. Nevertheless, an optimal CT evaluation of micronodular patterns requires additional thick-section CT scans.