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Middle lobar artery of right lung

The middle lobar artery is a branch of the right pulmonary artery that supplies the middle lobe of the right lung. It arises just distal to the origin of the superior lobar artery and courses laterally and anteriorly toward the middle lobe.

It typically divides into two main segmental branches: the medial segmental artery (for the medial segment of the middle lobe) and the lateral segmental artery (for the lateral segment). This arterial distribution corresponds to bronchopulmonary segments and ensures oxygenation of the middle lobe.

Anatomically, the middle lobar artery runs in close relation to the middle lobar bronchus and veins, and variations in branching pattern are common. Knowledge of its anatomy is essential for thoracic surgery, pulmonary embolism evaluation, and interventional procedures such as embolization.

Synonyms

  • Right middle lobar artery

  • Middle lobe branch of right pulmonary artery

  • Arteria lobaris media dextra

Function

  • Provides oxygen-depleted blood to the middle lobe of the right lung for gas exchange

  • Divides into medial and lateral segmental branches corresponding to bronchopulmonary segments

  • Plays a crucial role in pulmonary perfusion and oxygenation

  • Important for surgical resections (lobectomy, segmentectomy) and embolism detection

Branches

  • Medial segmental artery (A4) → medial bronchopulmonary segment

  • Lateral segmental artery (A5) → lateral bronchopulmonary segment

MRI Appearance

T1-weighted images:

  • Middle lobar artery appears as a signal void (black lumen) due to rapid blood flow

  • Vessel wall hypointense; adjacent lung parenchyma provides contrast

T2-weighted images:

  • Flowing blood remains a signal void

  • Thrombus within the artery appears as intermediate-to-high signal intensity

T2 TRUFISP (cardiac/respiratory-gated):

  • Middle lobar artery visualized as a bright vascular lumen with clear flow-related contrast

  • Excellent for dynamic assessment of pulmonary arterial patency and stenosis

STIR (Short Tau Inversion Recovery):

  • Fat suppression improves vessel visualization in the mediastinal fat planes

  • Pathology such as inflammation or perivascular edema appears hyperintense

T1 Post-Contrast (Gadolinium-enhanced MRI):

  • Middle lobar artery enhances homogeneously and brightly

  • Filling defects identify pulmonary embolism, stenosis, or extrinsic compression

  • Helpful for MR pulmonary angiography

MRI Non-Contrast Cardiac-Gated 3D Imaging:

  • Provides 3D reconstruction of pulmonary arteries without contrast

  • Middle lobar artery and its segmental branches are clearly shown

  • Useful in patients with renal dysfunction or contrast contraindications

CT Appearance

CT Pulmonary Angiography (CTPA):

  • Gold-standard for middle lobar artery imaging

  • Contrast opacifies lumen, showing origin, course, and bifurcation into medial and lateral branches

  • Detects pulmonary embolism (filling defect), stenosis, aneurysm, or vascular malformations

  • 3D reconstructions assist in thoracic surgery planning and embolism evaluation

CT images

Middle lobar artery of right lung anatomy CT axial image -img-00000-00000

CT images

Middle lobar artery of right lung anatomy CT axial image -img-00000-00000_00001

MRI image

Middle lobar artery of right lung mri image