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Superior intercostal artery

The superior intercostal artery is a branch of the costocervical trunk, which itself arises from the subclavian artery. It descends posteriorly and laterally, supplying the first and second intercostal spaces via its posterior intercostal branches. The artery courses along the neck of the first rib before giving rise to these branches, and it anastomoses with anterior intercostal arteries derived from the internal thoracic artery. It plays a crucial role in maintaining collateral circulation of the upper thorax.

Synonyms

  • Arteria intercostalis suprema

  • Branch of costocervical trunk

  • Posterior intercostal trunk of upper thorax

Function

  • Supplies arterial blood to the first and second intercostal spaces

  • Provides oxygenation to the intercostal muscles, overlying skin, and parietal pleura

  • Contributes to collateral circulation of the thoracic wall via anastomoses with anterior intercostal arteries

  • Supports thoracic musculature and rib cage stability

MRI Appearance

T1-weighted images:

  • Lumen appears as a flow void (black) due to rapid blood flow

  • Surrounding mediastinal and paravertebral fat appears hyperintense, aiding localization

  • Vessel wall is thin and hypointense

T2-weighted images:

  • Flowing blood also appears as a signal void

  • Adjacent edema or inflammatory changes may appear hyperintense, helping identify pathology (e.g., vasculitis)

  • Provides clear contrast with high-signal fat planes

STIR (Short Tau Inversion Recovery):

  • Suppresses fat, improving visualization of perivascular edema or inflammation

  • Normal artery remains a signal void

  • Pathological conditions (e.g., arteritis, extrinsic compression) appear bright hyperintense in surrounding tissues

T1 Post-Contrast (Gadolinium-enhanced):

  • Superior intercostal artery shows strong homogeneous enhancement

  • Contrast-enhanced MR angiography delineates its origin from the costocervical trunk, course, and branches

  • Useful for identifying stenosis, aneurysms, or vascular malformations

CT Appearance

Non-contrast CT:

  • The artery appears as a soft tissue density tubular structure near the neck of the first rib

  • Difficult to delineate without contrast, unless calcification is present

Contrast-enhanced CT (CT Angiography):

  • Lumen opacifies brightly, showing the origin from the costocervical trunk and branches to the first and second intercostal spaces

  • Demonstrates collateral circulation, vascular narrowing, or aneurysm

  • Multiplanar reconstructions (axial, coronal, sagittal) allow accurate mapping for surgical and interventional planning

CT images

Superior intercostal artery anatomy CT axial image -img-00000-00000