Multislice helical CT: the value of multiplanar image reconstruction in assessment of the bronchi and small airways disease

We examined 23 consecutive patients (11 males and 12 females with mean age of 56 years) with possible airway diseases to assess the impact of multiplanar image reconstruction (MPR) on the degree of confidence and accuracy in diagnosing bronchial abnormalities and emphysema. The thorax was scanned contiguously at 1 mm slice thickness using Siemens Volume Zoom Multislice CT scanner. Images were reconstructed at 1 mm slice thickness (lung windows L-600HU W-1600HU utilizing high spatial frequency algorithm) in the axial (10 mm apart), sagittal (4 images per lung) and coronal (6 images) plane. Paddle wheel image reconstructions were also performed in the assessment of bronchiectasis. Axial images were assessed with and without the help of MPR by three chest radiologists at two separate occasions (at least 4 weeks apart). The presence of bronchiectasis, emphysema and bronchiolitis in each lobe was documented on a confidence scale of 0 to 3. The overall mean confidence for each observer with and without MPR was compared. Consensus diagnosis was used as the gold standard for the assessment of the diagnostic accuracy of each observer. A confidence score of 2 or more for any lobe was considered diagnostic of the particular airway disease. The diagnostic accuracy for each observer with and without MPR was compared. Consensus reporting diagnosed bronchiectasis in 7 patients (30.4%), bronchiolitis in 5 patients (21.7%) and emphysema in 12 patients (52%). MPR did not increase the confidence of assessing the different abnormalities for all observers but improvement in diagnosing bronchiectasis was noted in two observers. The improvement did not reach statistical significance. However, agreement between observers in the diagnosis of bronchiectasis and emphysema was improved when the MPR images were used in conjunction with standard axial imaging (Kappa statistic improved from 0.29 to 0.54 for bronchiectasis and from 0.7 to 0.81 for emphysema). Agreement on the diagnosis of bronchiolitis was not improved by MPR for all observers. Our results suggest that MPR seems to improve the confidence in diagnosing bronchiectasis and emphysema.