Review of high-resolution CT of the lung.

High-resolution computed tomography (HRCT) of the lung provides detailed visualization of the lung parenchyma and is being used to evaluate chronic interstitial lung disease. The technique of HRCT involves use of 1-2-mm-thick collimation scans with a high spatial frequency algorithm. To fully appreciate the HRCT findings, one should understand the anatomy of the secondary pulmonary lobule. Lung disease can be classified according to pattern (linear areas, nodular areas, areas of decreased attenuation, and areas of ground-glass attenuation) and distribution (peripheral, axial, and parenchymal). Identifying the pattern and distribution of disease helps in formulating a differential diagnosis. Furthermore, when biopsy is necessary, distribution of lung disease, as seen on HRCT scans, can help in planning the approach.