Thyroid scan (Tc-99m)

Tc-99m [pertechnetate] thyroid scan is a functional nuclear medicine study used to assess the thyroid gland.

  • patient preparation
    • fast for 4 hours prior to exam
  • radiopharmaceutical
  • dose and route of administration
    • 3-5 mCi IV
  • time of imaging
    • 20 minutes after Tc-99m pertechnetate administration
  • equipment
    • camera: gamma camera
    • collimator: pinhole
    • window: 20% energy window centered at 140 KeV
  • procedure
    • obtain anterior, LAO, and RAO views
    • mark chin, suprasternal notch, palpable nodules, and surgical scars

Interpretation:

Radiotracer uptake on the thyroid scan needs to be interpreted with biochemical thyroid function tests and thyroid antibodies (e.g. antithyroglobulin, antimicrosomal, thyrotropin receptor). The combination of these results can usually distinguish between the causes of thyroid dysfunction.

Increased uptake:

  • Graves disease
  • Hashitoxicosis
  • subacute thyroiditis (thyrotoxic phase)

Normal uptake:

Decreased uptake: 

See also

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Article information

rID: 15560
Section: Physics
Synonyms or Alternate Spellings:
  • Tc-99m thyroid scan
  • Tc-99m pertechnetate thyroid scan

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