Distribution pattern of computed tomography findings in patients with bronchiolitis obliterans organizing pneumonia

The authors evaluated high-resolution computed tomography (HRCT) findings in 15 patients with biopsy-proven bronchiolitis obliterans organizing pneumonia (BOOP). Special attention was paid to lobar distribution to establish a predominant distribution pattern for this disease.

Fifteen patients (average age, 61.8 years) with BOOP underwent computed tomography examinations. The examination technique included a slice thickness of 4 mm with a 4-mm interval; matrix size was 256 x 256 pixels. In all patients, additional HRCT images with a 2-mm slice thickness and a 10-mm interval (matrix, 512 x 512 pixels) were obtained. Interpretation included assessment of pulmonary, pleural, and mediastinal involvement. Special attention was paid to the distribution pattern of pulmonary abnormalities.

High-resolution computed tomography in all patients demonstrated areas of air space consolidation in a multifocal but peripheral distribution. The right lower lobe was involved in 60% of the patients, the left lower lobe in 53%, the middle and right upper lobes in 20%, and left upper lobe in 23%. Five patients had ground-glass opacities in addition to the areas of air space consolidation, with the incidence in these patients being 100% in the right lower lobe. 80% in the left lower and middle lobes, 60% in the right upper lobe, and 20% in the left upper lobe. Nodules were found in two patients, and the left lower and middle lobes were affected in both. In one patient, the right lower lobe was affected. The interstitium was thickened in 66%, with axial involvement in 20%, septal thickening in 30%, and peripheral regions affected in 50%. Bronchiectasis was present in 60% of all patients studied, predominantly located in the lower lobes.

Bronchiolitis obliterans organizing pneumonia presents a predominant peripheral, bilateral, and nonsegmental distribution, with the lower and middle lobes affected more than the upper lobes.