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Inferior thyroid artery

The Inferior Thyroid Artery (ITA) is a vital branch of the thyrocervical trunk, playing a crucial role in supplying blood to the thyroid gland and adjacent structures in the neck. It is the primary vascular supply to the posterior and inferior aspects of the thyroid gland, and its identification is essential in head and neck surgery and imaging. Understanding its anatomical course, branches, and imaging features is key for radiologists and clinicians, especially for procedures such as thyroidectomy, embolization, or neck tumor assessment.

Synonyms

  • ITA

  • Arteria thyroidea inferior

  • Inferior thyroidal artery

Function

  • Main arterial supply to the posterior and inferior thyroid gland.

  • Supplies the parathyroid glands.

  • Provides branches to the esophagus, trachea, and adjacent neck muscles.

  • Important in surgical and interventional procedures involving the thyroid and neck.

Anatomy & Course

  • Origin: Branches off the thyrocervical trunk (a branch of the subclavian artery).

  • Course: Ascends medially towards the lower pole of the thyroid gland, passing posterior to the carotid sheath and recurrent laryngeal nerve.

  • Branches: Provides ascending and descending branches, and several small twigs to the parathyroids, trachea, and esophagus.

MRI Appearance

  • T1-weighted:

    • The artery appears as a flow void (dark signal) due to fast-moving blood.

    • Not directly visualized unless thrombosed or surrounded by pathology.

  • T2-weighted:

    • Also seen as a flow void (dark signal).

    • Adjacent soft tissue structures and any related pathology may be better appreciated.

  • STIR (Short Tau Inversion Recovery):

    • Vessel itself remains dark (flow void).

    • Useful for highlighting edema or inflammation in adjacent soft tissues.

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

    • ITA visualized as a high signal (bright) structure due to flow-related enhancement.

    • Helps in mapping vascular anatomy and detecting variants or pathology.

CT Appearance

  • Non-contrast CT:

    • Inferior thyroid artery may not be well seen due to small caliber and similar attenuation to adjacent tissues.

    • Can sometimes be inferred by its course if calcified or surrounded by pathology.

  • Contrast-Enhanced CT (CT Angiography/CTA):

    • Clearly visualized as a small, enhancing vessel coursing medially toward the lower pole of the thyroid gland.

MRI images

Inferior thyroid artery mri axial image