Small bronchiectases and bronchiolectases in high resolution computed tomography (HRCT).

Large bronchiectases form characteristic patterns, and are visible even on plain chest radiograms. Small bronchiectases and bronchiolectases may not be visible even in conventional CT. HRCT is a diagnostic method, which optimizes the spatial resolution and achieves the best quality of lung images, and therefore in diagnosis of bronchiectases HRCT is a diagnostic method of choice. In diagnosis of small bronchiectases and bronchiolectases the knowledge of typical HRCT patterns is essential. They include "signet-ring sign", "tram track", lack of normal tapering, visibility of bronchi in peripheral lung areas, within 2 cm from the parietal pleura. In varicose bronchiectases the "string of pearls" and in cystic "cluster of grapes" are typical appearances.