Evaluation of tracheobronchial abnormalities and variations with HIGH resolution computed tomography

Introduction and Objective: In this study, patient images were restrospectively accessed using the Infinit-pacs system in the patient population evaluated by high resolution computed tomography. In each patient, trachea, both main bronchi and all other lobe bronchi were examined in the axial, coronal and sagittal plane. The frequency, location and types of tracheal diverticulum, tracheal bronchus and cardiac bronchus were determined, and their incidence according to gender was examined. Segmental branching patterns of the right upper lobe, right middle lobe, right lower lobe basal, left upper lobe, left upper lobe lingula, and left lower lobe basal bronchi were examined, and incidence was seen. In addition, anomalies and variations such as subsuperior bronchus, bronchial hypoplasias were also examined. The results were compared with previous studies. The findings were aimed to be brought to the literature and to provide guidance and foresight to physicians interested in the tracheobronchial system before diagnosis, treatment and invasive procedures. Results: We retrospectively reviewed 1289 patients who underwent HRCT for thoracic in the Department of Radiology at Dicle University Medical School in 2018 for trachoebronchial anomalies variations and bronchial segmental branching patterns. 687 (53,3%) of the patients were female and 602 (46,7%) were male. The mean age was 48,6 years. In our study, the incidence of tracheal diverticulum was 2,5% and it was observed more frequently in males. Similar to literature, 100% of tracheal diverticula originate in the right upper paratracheal area and right posteolateral wall of the trachea. The incidence of tracheal bronchus was found to be 1.08% and there was no significant difference between male and female gender. The most common origin of tracheal bronchus is the right main bronchus and trachea, and the most common type is displaced. 11 (0.85%) cases with accessory cardiac bronchus were detected. The most common origin is intermediate bronchus. We have identified two types as blunt terminated and ventilated lung segment. We found the incidence of subuperior bronchus as 21,8%. The most common segmental branching pattern of right upper lobe bronchus was trifurcation (B1, B2, B3) with 87,9%, while bifurcation was 10,6% and quadrification pattern was 1,5%. The right middle lobe bronchus showed segmental branching in 94,6% of horizontal bifurcation (lateral and medial segments), trifurcation in 3,9% and superior-inferior bifurcation in 1,5%. In the right lower lobe basal bronchus; 77% trifurcation, 19,3% quadrification (B7, B8, B9, B10) and 3,3% bifurcation were observed. Four types of trifurcation patterns and five types of bifurcation patterns were detected. Trifurcation patterns were the most commonly observed trifurcation pattern (B7, B8, B9 + B10). Among the bifurcation types, bifurcation (B8, B9 + B10) was the most common type of lateral and posterior basal segments without medial segment. In the right lower lobe basal bronchus; The type of tirfurcation (B8, B9, B10) in 7 cases with no medial segment was detected only in women. The most common pattern in the left upper lobe bronchus was bifurcation (B1 + B2, B3) with 97,8%. In the left upper lobe lingula; Bifurcation type was seen in the form of superior and inferior segments with 99%. In the left lower lobe basal bronchus; 52,8% bifurcation, 43% trifurcation and 4,3% quadrification were detected. Trifurcation pattern was more frequent in male patients and bifurcation pattern was more frequent in women. We found a total of four bifurcation and five trifurcation patterns. Bifurcation types were the most common (B7 + B8, B9 + B10), and trifurcation patterns were the most common (B7 + B8, B9, B10) Conclusion: Our study shows that the frequency of tracheal diverticulum, tracheal bronchus and accessory cardiac bronchus is more frequent than most studies in the literature. We found that all tracheal diverticula originate from the right posteolateral wall of the trachea and are significantly more common in males. Most tracheal bronchi were associated with apical segment of right upper lobe. We found numerous branching patterns at the segmental level, especially in the lower lobe basal bronchi. We observed that the bronchial lingula and the left upper lobe bronchus were the least variation. In conclusion, since tracheobronchial anomalies and variations show a wide spectrum, it is important to know these anomalies and variations prior to any kind of surgery and interventional procedure in diagnosing tracheobronchial diseases, investigating the etiology of symptoms.