The Application Of Post-processing Of 64-slice Spiral CT In The Bronchial Anatomy Of Left Lung

PurposeFamiliarity with prevailing pattern and variations in the bronchial tree is not only essential for the anatomist to explain bronchial variation in bronchial specimens and the radiologist to interpret an otherwise confusing CT finding, but also useful for guiding bronchoscopy and instructing pulmonary segmental resection. The purpose of our study was to classify the bronchial branching patterns of the left lung with 3D images of 64 slice CT and to study how to identify the main ramifications at transverse thin-section CT.Methods216 patients with routine thorax scans were enrolled. The images of bronchial tree, virtual bronchoscopy were reconstructed using post-processing technique of multi-detector row CT. The 3D (3 dimensional) bronchial tree, which was performed with seed mode, and virtual bronchoscopy, which were performed with fly through mode, are based on the post-processing technology of shaded surface display which renders axial CT data into simulated 3D images, and they were obtained using the following parameter: section thickness, 1.0-mm; reconstruction interval, 0.7-mm; standardized mediastinal window setting. The transverse thin-section CT images were obtained using the following parameter: section thickness, 1.5mm; reconstruction interval, 1.0-mm; bone algorithms; standardized lung window.The identification of segmental bronchi depends on bronchial lumen diameter and branching direction of 3D bronchial tree. The classification of segmental bronchial branching patterns depends on the trifurcation or bifurcation of lobar bronchi of 3D bronchial tree and the shape of carina in VB images. In this study, we tried to identify the segmental bronchial main ramification types, combining the two post-processing images of bronchial tree and VB, and study how to recognize them in transverse thin-section CT. We also attempt to display the unusual types of bronchi which can be seen in less than 5 percent of the total number and the subsuperior segmental with 3D image. Two experienced radiologist interpreted all the 3D and transverse thin-sectionCT images, and reached their conclusion consensus.ResultsThe segmental bronchial ramifications of the left superior lobe were classified intothree types mainly, i.e., common stem of apical and posterior segmental bronchi (64%,138/216); trifurcation (23%, 50/216); common stem of apical and anterior segmentalbronchi (10%, 22/216), and they could be identified at two typical sections oftransverse thin-section CT.There were two major types in left basal segmental bronchi, i.e., bifurcation (75%,163/216), trifurcation (18%, 39/216), and they could also be identified at two typicalsections of transverse thin-section CT.Of 216 cases of left superior lobar bronchial reviewed in our study, 6 cases wereunusual variation. In one case, B1 originated from left superior lobar bronchus but notleft upper divisional bronchus; in one case, the left superior lobar bronchus triftircatedinto three branches; in one case, the left superior lobar bronchus branched fourbronchi; in one case, the left upper divisional bronchus branches four bronchi.Unexpectedly, the left lingual divisional bronchial trifurcation can be found in 2 cases.Of 216 left inferior bronchial cases, there are 14 cases unusual variation. In 8 cases,the basal trunk bronchus bifurcates into B10 and the stem of B7, B8 and B9; aseparate origin from the basal trunk of the medial basal bronchus was identified in 5cases; in one case, the basal trunk bronchus divides into four branches.Various Subsuperior bronchi which run backward, horizontally and occupy aparavertebral position were identified. 2 cases originated from the basal trunkbronchus; 15 cases originated from the stem of B7 and B8; 65 cases originated fromthe stem of B9 and B10.An accessory bronchus which originated from the stem of B7 and B8 or B7 wasidentified in 138 cases. It should be distinguished from the subsuperior bronchus, forit run laterally to the lateral aspect of the lung. An accessory bronchus whichoriginated from the lingual divisional bronchus could also be found in 5 cases.Conclusion Our study has offered simplified branching patterns of bronchi and demonstrated various unusual bronchial branching patterns perfectly with 3D images. More subsuperior and accessory bronchi has been found, compared with the previous results. Moreover, we have also revealed how to identify the main branching patterns in transverse thin-section CT with the introduction of 3D images.ApplicationFamiliarity with prevailing pattern and their variations in the bronchial tree is essential for the anatomist to explain bronchial variation in bronchial specimens and the radiologist to interpret an otherwise confusing CT finding. Moreover, the detailed bronchial anatomy provides an accurate "roadmap" for the bronchoscopist in particular. Resection of a single segment of the lung is practicable, accurate identification of segmental bronchial origination is a prerequisite for acquisition of information for planning operation. In addition, our results may provide useful information for the automated nomenclature of bronchial branches extracted from CT images which has not reach agreement.