Bronchial branching patterns and volumetry in the right upper lobe: impact on segmentectomy planning

Abstract

Objectives: The use of segmentectomy is expected to increase. However, understanding of the segmental bronchial branching is limited. Herein, we aimed to investigate bronchial branching pattern complexity and segmental volumetry of the right upper lung lobe to develop an accurate understanding of segmental anatomy and contribute to the advancement of safe and efficient lung segmentectomy.

Methods: We evaluated chest computed tomography scans of 303 patients and categorized the branching of segmental bronchi (segment 1, apical; segment 2, posterior; and segment 3, anterior) into 4 major types (typical trifurcated, bifurcated non-defective, bifurcated defective and atypical trifurcated) and 11 subtypes. Segmental volumetry was performed to determine the predominant segment in each case (volume difference <5% was considered equal). Branching complexity was evaluated separately for volumetry-predominant and volumetry-non-predominant segments.

Results: Trifurcated non-defective was the most frequent branching type (64.4%), followed by bifurcated non-defective (22.1%), bifurcated defective (8.6%) and trifurcated half-defective (4.0%). In terms of segmental volumetry, most cases had a one-segment-predominant distribution (71%) and only 5% of cases had equal distribution (segment 1 = segment 2 = segment 3). More than half of the cases had a segment 3-predominant distribution (52%). Branching complexity analysis revealed that the volumetry-non-predominant segment was associated with a higher risk of complex branching patterns compared with the volumetry-predominant segment (37% vs 19%, respectively; P < 0.005).

Conclusions: Volumetric assessment of the right upper lobe showed a heterogeneous segmental volume distribution. Care should be taken during lung segmentectomy of the volumetry-non-predominant segments because of the high risk associated with complex bronchial branching patterns.

Clinical trial registration: No. 4840.

Keywords: Bronchial branching pattern; Pulmonary segmentectomy; Right upper lobe; Volumetry.

Figure 1:

Actual method for segmental volumetry of the right upper lobe. First, bronchial bifurcation in the right upper lobe is identified. Subsequently, each target bronchus is selected, and the segmental volume is automatically calculated.

Figure 2:

Major classification and representative 3D image of right upper lobe bronchus. *The first branch of the right upper lobe bronchus.

Figure 3:

(A) Median volume of each right upper lobe segment. (B) Volume distribution of the 3 segments and their frequencies in the right upper lobe.

Figure 4:

Frequencies of bronchial patterns in segmentectomy planning for each predominant pattern. In the S³-predominant type, the frequency of the B³ simple bronchial pattern is 86%, while that of the B³ complex pattern is 16%; in S¹ or S² segmentectomy, the frequency of B¹ and B² complex patterns is 35% (P < 0.001). In the S¹-predominant type, the B¹ complex bronchial pattern frequency is 29%; in S² or S³ segmentectomy, the frequency of B² and B³ complex patterns is 29% (P = 1). In the S²-predominant type, the B² complex pattern frequency is 27%; in S¹ or S³ segmentectomy, the frequency of B¹ and B² complex patterns is 43% (P = 0.16).