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Superior phrenic artery

The superior phrenic arteries are small paired branches of the thoracic aorta, arising near the aortic hiatus of the diaphragm (around the level of T10–T12). They course downward and laterally to supply the posterior superior surface of the diaphragm, often anastomosing with branches of the musculophrenic and pericardiacophrenic arteries.

Although small in size, they form part of an extensive collateral network of diaphragmatic blood supply, together with the inferior phrenic, musculophrenic, and pericardiacophrenic arteries. Variations are common — they may arise from the lower thoracic intercostal arteries instead of directly from the thoracic aorta.

Clinically, they are relevant in thoracic surgery, diaphragmatic repair, and interventional radiology, especially when planning embolization or evaluating diaphragmatic tumors and vascular lesions.

Synonyms

  • Arteriae phrenicae superiores

  • Superior diaphragmatic arteries

Function

  • Provide arterial blood supply to the posterior and superior portion of the diaphragm

  • Contribute to collateral circulation of the thoracic and abdominal diaphragmatic surface

  • Assist in maintaining vascular perfusion during respiratory movement

Branches

  • Typically do not have distinct named branches

  • Anastomose with:

    • Musculophrenic artery

    • Pericardiacophrenic artery

    • Inferior phrenic artery

MRI Appearance

T1-weighted images:

  • Blood flow produces a signal void (black lumen)

  • Vessel appears as a fine tubular structure adjacent to the thoracic aorta and diaphragm

  • Surrounding fat planes are hyperintense, aiding in localization

T2-weighted images:

  • Arterial lumen remains a signal void due to fast flow

  • Abnormalities (e.g., aneurysm, mural thrombus) may alter expected appearance

STIR (Short Tau Inversion Recovery):

  • Fat suppression highlights the artery against surrounding fat planes of the diaphragm and mediastinum

  • Perivascular edema or inflammation appears hyperintense

T1 Post-Contrast (Gadolinium-enhanced):

  • Lumen demonstrates bright homogeneous enhancement

  • Useful for identifying small-caliber arteries, vascular malformations, or diaphragmatic tumors

MRA (Magnetic Resonance Angiography):

  • Visualizes superior phrenic artery origin from thoracic aorta

  • Provides 3D vascular mapping of anastomoses with phrenic and intercostal arteries

  • Helpful for surgical or interventional planning

CT Appearance

Non-contrast CT:

  • Artery appears as a tiny soft tissue density at the aortic hiatus region

  • Not well seen unless calcified or enlarged

CT Angiography (CTA):

  • Clearly demonstrates origin, course, and anastomoses of the superior phrenic artery

  • Useful for identifying vascular variants, diaphragmatic tumors, or trauma-related bleeding

  • Provides high-resolution multiplanar reconstructions of thoracic aortic branches

MRI image

Superior phrenic artery anatomy MRI axial image -img-00000-00000

CT images

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

CT images

Superior phrenic artery anatomy CT axial image -img-00000-00000_00001