Bronchiectasis: Accuracy of high-resolution CT in the differentiation of specific diseases

OBJECTIVE. The aim of the study was to determine whether various causes of bronchiectasis can be differentiated by the pattern and distribution of abn ormalities seen on high-resolution CT. MATERIALS AND METHODS. The retrospective study included 82 consecutive pati ents who had a specific diagnosis of bronchiectasis proven by appropriate c linical and laboratory criteria. AU patients underwent high-resolution CT s canning (1- to 1.5-mm collimation). The CT scans were assessed far the pres ence, extent, type, and anatomic distribution of bronchiectasis by two inde pendent observers who were not aware of the clinical data. The observers re corded their most likely diagnosis and the degree of confidence in that dia gnosis. RESULTS. The two independent observers made a correct diagnosis in 61% of c ases (100/164 interpretations). On average, a correct diagnosis was made in 19 (68%) of 28 cases of cystic fibrosis, 16 (67%) of 24 cases of previous tuberculosis, six (43%) of 14 cases of previous childhood infection, five ( 56%) of nine cases of allergic bronchopulmonary aspergillosis, and four (57 %) of seven cases of other causes of bronchiectasis. We found moderate agre ement between the observers for the correct diagnosis (kappa = .53) and goo d agreement for the presence or absence of bronchiectasis in each lobe (kap pa = .71). CONCLUSION. The pattern and distribution of abnormalities revealed by high- resolution CT in patients with bronchiectasis are influenced by the underly ing cause. Bilateral, predominantly upper lobe, bronchiectasis is seen most commonly in patients with cystic fibrosis and allergic bronchopulmonary as pergillosis, unilateral upper lobe predominance in patients with tuberculos is, and lower lobe predominance in patients after childhood viral infection .