Linear opacities on HRCT in bronchiolitis obliterans organising pneumonia

The aim of this study was to report the resolution computed tomography (HRC T) appearances of linear opacities that may occur in isolation or in combin ation with other changes in bronchiolitis obliterans organising pneumonia ( BOOP). Eleven patients with BOOP and linear opacities on HRCT were identifi ed at three independent teaching hospitals. The HRCT images and clinical co urse of each patient were reviewed. Two distinct types of linear opacity we re identified. The type-1 opacity extended in a radial manner along the lin e of the bronchi towards the pleura and was usually intimately related to b ronchi. The type-2 opacity occurred in a subpleural location and bore no re lationship to the bronchi. Both types occurred most commonly in the lower l obes, frequently were associated with multi-focal areas of consolidation an d usually completely resolved with treatment. There was no associated bronc hiectasis, irreversible volume loss or a reticular or honeycomb pattern. In 2 patients linear opacities were the sole abnormality on HRCT. Bronchiolit is obliterans organising pneumonia may occur in a pure "linear form" or HRC T may demonstrate linear opacities in addition to multi-focal consolidation .