Radiologic Evaluation

The technique of high resolution CT (HRCT) requires thin (1–1.5 mm) sections and a special reconstruction algorithm to maximize detail in the lung parenchyma [ 1 ] (Fig. 2.1 ). HRCT images may be reconstructed from a volumetric dataset or may be acquired using noncontiguous images at 1–2 cm intervals. If volumetric acquisition is performed, coronal and sagittal reconstructions may be obtained, and may be very helpful in understanding distribution of disease. Careful attention to technique is required to ensure high quality images. In particular, Abstract High resolution CT is useful for early detection and characterization of diffuse lung diseases. Optimal CT evaluation requires careful attention to technique. Radiologic diagnosis is based on the use of standard descriptive terms and the distribution of abnormality in the craniocaudal and axial planes. Confi dent CT diagnoses of several diffuse diseases, including usual interstitial pneumonia, sarcoidosis, hypersensitivity pneumonitis, smoking-related lung injury, Langerhans histiocytosis, lymphangioleiomyomatosis, based on typical CT fi ndings and made in the appropriate clinical context, are usually correct. However, certain other radiologic fi ndings, particularly ground-glass abnormality, consolidation and reticular abnormality, are relatively nonspecifi c and will usually require further diagnostic evaluation.