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Calcarine artery

The calcarine artery is the terminal cortical branch of the posterior cerebral artery (PCA), typically arising from the P2 segment. It courses posteriorly along the calcarine sulcus on the medial surface of the occipital lobe. The artery supplies the primary visual cortex (Brodmann area 17), making it essential for visual processing. Variations exist, with the calcarine artery occasionally sharing distribution with the parieto-occipital artery or showing duplications. Occlusion of this artery results in contralateral homonymous hemianopia due to ischemia of the calcarine cortex.

Function

  • Provides the primary vascular supply to the calcarine cortex (primary visual cortex)

  • Maintains visual processing functions in the occipital lobe

  • Contributes to collateral circulation with the parieto-occipital and posterior temporal arteries

  • Critical in stroke syndromes affecting vision

Synonyms

  • Calcarine branch of posterior cerebral artery

  • PCA calcarine artery

  • Arteria calcarina

MRI Appearance

T1-weighted images:

  • The calcarine artery itself is usually not directly visualized without angiographic sequences.

  • Flowing blood produces a signal void (black tubular structure) within the calcarine sulcus region.

  • Post-contrast MR angiography (MRA) can demonstrate the artery as an enhancing linear vascular structure.

T2-weighted images:

  • Appears as a flow void within the medial occipital sulcus (calcarine sulcus).

  • Adjacent visual cortex is normal intermediate signal.

  • Infarction in its territory appears as hyperintense signal in the occipital cortex.

STIR (Short Tau Inversion Recovery):

  • Not typically used for vascular evaluation.

  • Can highlight edema in the visual cortex in cases of calcarine artery infarction.

T1 Post-Contrast (Gadolinium-enhanced):

  • Vessel lumen enhances on contrast-enhanced MR angiography (CE-MRA).

  • In pathology, enhancement may indicate vascular malformations, aneurysms, or inflammatory vasculopathy.

CT Appearance:

  • On routine non-contrast CT, the artery itself is not visualized, though its bony sulcus can sometimes be inferred.

  • Acute occlusion may present as hyperdense vessel sign if thrombosed.

CT Angiography (CTA):

  • Clearly demonstrates the calcarine artery as a small enhancing vessel running along the calcarine sulcus.

MRI images

Calcarine artery