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Carotid bifurcation

The carotid bifurcation is the anatomical point where the common carotid artery divides into the internal and external carotid arteries, typically located at the level of the upper border of the thyroid cartilage (C3-C4 vertebral level). This bifurcation is a crucial site for vascular pathologies, such as atherosclerotic plaque formation and carotid artery stenosis, which have significant clinical implications in cerebrovascular events like stroke. The carotid bifurcation is also closely associated with the carotid body, an important chemoreceptor organ.

Synonyms

  • Carotid fork

  • Carotid bulb (specifically refers to the dilated area at the bifurcation)

  • Bifurcation of the common carotid artery

  • Common carotid bifurcation

Function

  • Acts as the division point for the common carotid artery into the internal and external carotid arteries, supplying blood to the brain and face/scalp respectively.

  • The carotid bulb at the bifurcation contains baroreceptors and chemoreceptors involved in the regulation of blood pressure and blood gas levels.

  • Serves as a common location for the formation of atherosclerotic plaques due to turbulent blood flow.

MRI Appearance

  • T1-Weighted (T1W):

    • Vessel lumen appears as a flow void (dark signal) if patent.

    • Vessel wall may show mild low to intermediate signal; plaques, if present, may show variable signal (lipid-rich, hemorrhagic, or fibrous content).

    • Carotid bulb seen as a focal dilation at the bifurcation.

  • T2-Weighted (T2W):

    • Vessel lumen remains dark (flow void).

    • Atherosclerotic plaques may demonstrate high signal if they contain a lipid-rich necrotic core or intraplaque hemorrhage.

    • Wall thickening or mural pathology (e.g., dissection) may be better delineated.

  • STIR (Short Tau Inversion Recovery):

    • Fat suppression improves contrast of the vessel wall and adjacent soft tissues.

    • Helpful in identifying vessel wall edema, inflammation, or fresh hemorrhage in plaques.

  • Time-of-Flight (TOF) MR Angiography:

    • Provides non-contrast visualization of blood flow.

    • Lumen appears bright due to flow-related enhancement.

    • Allows visualization of the bifurcation, assessment of stenosis or occlusion, and identification of abnormal flow patterns.

CT Appearance

  • Carotid bifurcation seen as division of the common carotid into two branches (internal and external) at the level of C3-C4.

  • Contrast-enhanced CT may show a hyperdense (bright) lumen.

  • Calcified plaques appear as hyperdense foci in the vessel wall.

  • Useful for evaluating vessel wall calcifications and overall vascular anatomy.

CTA (CT Angiography) Appearance

  • High-resolution, contrast-enhanced imaging of the carotid arteries.

  • Clearly demonstrates the bifurcation, lumen, and vessel wall.

  • Accurately detects and quantifies degree of stenosis, identifies plaques, ulcerations, and dissection.

  • 3D reconstructions provide comprehensive visualization for surgical or endovascular planning.

If you need refere

MRI images

Carotid bifurcation axial t2

MRI images

Carotid bifurcation coronal mri image