●High resolution computed tomography (HRCT, also called thin-section CT scanning) provides more detail than either chest radiography or conventional CT scanning, with an overall sensitivity of 95 percent and a specificity approaching 100 percent. Compared to chest radiography, HRCT can more accurately assess the pattern and distribution of diffuse lung disease, which may be beneficial when trying to narrow the differential diagnosis or define a target for lung biopsy.
•HRCT patterns include linear and reticular opacities, nodular opacities, large confluent opacities (eg, ground-glass opacities, consolidation), and decreased parenchymal opacity (eg, emphysema, cystic lesions, mosaic attenuation, gas trapping). These patterns may be accompanied by parenchymal bands and architectural distortion.
•Distributions of disease include apical versus basal, central versus peripheral, anterior versus posterior, and diffuse.
●Major diseases that can be optimally characterized by HRCT include emphysema, bullous disease, airways diseases (eg, bronchiectasis, bronchiolitis), lymphangitic carcinomatosis, sarcoidosis, the idiopathic interstitial pneumonias, asbestosis, Langerhans cell histiocytosis, lymphangioleiomyomatosis, Pneumocystis pneumonia (PCP, now called Pneumocystis jirovecii pneumonia), hypersensitivity pneumonia, severe acute respiratory syndrome from COVID-19, and asymptomatic interstitial lung abnormalities.
