Pulmonary nodules: optimal slice thickness of CT in revealing bronchial imageology

Abstract

The aim of our study was to determine an optimal slice thickness that was efficient in revealing bronchial imageology of pulmonary nodules (PNs) on multi-slice spiral computed tomography (MSCT) images preliminarily. Fifty-four patients with 62 PNs (diameter ≤ 3 cm) underwent multidetector-row computed tomography of the chest in a single-breath-hold technique. The raw data were acquired with a collimation of 0.625 mm. Three sets of contiguous images were reconstructed with 1-, 2-, and 5-mm slice thickness, respectively. Bronchial imageology of SPNs on the CT images presented in 1-, 2-, and 5-mm slice thickness was compared. Using the 1-mm sections as the gold standard, an optimal slice thickness in revealing bronchial imageology of PNs was determined. Bronchial imageology of PNs on the CT images presented in 1 mm slice thickness involved 85 bronchi (35 second-fourth generation bronchi; 50 fifth-eighth generation bronchi). Bronchial imageology on 2-mm-thick sections was as same as that on 1-mm-thick sections in 34 second-fourth generation bronchi. No statistically significant difference in number of second-fourth generation bronchi with same bronchial imageology was found between that on 2-mm-thick images and 1-mm-thick images (P = 0.836 > 0.05). Bronchial imageology on 5-mm-thick sections was as same as that on 1-mm-thick sections in 24 second-fourth generation bronchi. There was statistically significant difference in number of second-fourth generation bronchi with same bronchial imageology between that on 5-mm-thick images and 1-mm-thick images (P = 0.026 < 0.05). Bronchial imageology on 2-mm-thick sections was as same as that on 1-mm-thick sections in 38 fifth-eighth generation bronchi. There was statistically significant difference in number of fifth-eighth generation bronchi with same bronchial imageology between that on 2-mm-thick images and 1-mmthick images (P = 0.029 < 0.05). Bronchial imageology on 5-mm-thick images was as same as that on 1-mm-thick images in 31 fifth-eighth generation bronchi. There was statistically significant difference in number of fifth-eighth generation bronchi with same bronchial imageology between that on 5-mm-thick sections and 1-mm-thick sections (P = 0.001 < 0.05). It is suggested that the use of 2-mm slice thickness is suitable in revealing second-fourth generation bronchi and the use of 1-mm slice thickness is suitable in revealing fifth-eighth generation bronchi.