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Anterior basal segmental bronchus of right lung (B7+8, B8)

The anterior basal segmental bronchus (B8) is one of the four basal segmental bronchi of the right lower lobe, along with the medial basal (B7), lateral basal (B9), and posterior basal (B10) bronchi. It arises from the right lower lobe bronchus and runs anteroinferiorly to supply the anterior basal segment of the right lower lobe. This segment corresponds to the anteromedial portion of the lower lobe, lying against the diaphragm and costal surface. The anterior basal bronchus (B8) is important in drainage of secretions, pulmonary infection localization, and surgical resection planning.

Synonyms

  • B8 bronchus

  • Right anterior basal bronchus

  • Anterior basal segmental bronchus of right lower lobe

  • Sometimes grouped as B7+8 (depending on branching variation)

Function

  • Provides ventilation to the anterior basal segment of the right lower lobe

  • Maintains effective gas exchange in the anteroinferior part of the lung

  • Plays a role in mucus clearance and drainage of the basal segments

  • Serves as a bronchoscopic and radiological landmark in segmentectomy and lobectomy procedures

CT Appearance

Lung Window:

  • Appears as an air-filled tubular structure branching anteroinferiorly from the right lower lobe bronchus

  • Lumen is hypodense (black) with thin, smooth bronchial walls in normal conditions

  • Pathology:

    • Wall thickening (bronchitis)

    • Endobronchial filling defects (mucus plug, foreign body, tumor)

    • Tree-in-bud opacities in its distribution (infection, aspiration)

    • Atelectasis or consolidation in the B8 segment

Mediastinal Window:

  • Shows the soft tissue rim of the bronchial wall

  • Highlights relationship of B8 to adjacent pulmonary vessels and mediastinal structures

  • Useful for evaluating extrinsic compression by lymphadenopathy or mass lesions

Contrast-enhanced CT (CECT):

  • Bronchial wall and adjacent vessels enhance, improving detection of pathology

  • Excellent for evaluating endobronchial tumors, bronchial narrowing, and peribronchial invasion by carcinoma

  • HRCT reconstructions allow precise visualization of B8 course and branching for surgical planning

MRI Appearance

T1-weighted images:

  • Air in the lumen = signal void (black)

  • Bronchial wall = low signal intensity rim

  • Surrounded by hyperintense peribronchial fat

T2-weighted images:

  • Air-filled lumen remains a signal void

  • Mucus or fluid in lumen = bright hyperintense signal

  • Thickened/inflamed walls = intermediate to hyperintense signal

T1 Post-Contrast (Gadolinium-enhanced):

  • Normal bronchial wall enhances as a thin rim

  • Pathology (e.g., neoplasm, inflammatory changes) appears as irregular, nodular, or thickened enhancement

  • Endobronchial lesions show focal intraluminal enhancement

CT images

Anterior basal segmental bronchus of right lung (B7+8, B8) anatomy CT coronal image -img-00000-00000

CT images

Anterior basal segmental bronchus of right lung (B7+8, B8) anatomy CT coronal image -img-00000-00000_00001