THYROID SCAN

Evaluate the size and shape of thyroid tissue.

Evaluate clinical laboratory tests suggestive of abnormal thyroid function.

Evaluate hyperthyroidism, suspected focal or diffuse thyroid disease, congenital thyroid abnormalities, function of thyroid nodules, and patients at risk for thyroid neoplasm.

Family or personal hx of thyroid disease

Goiter or hx of goiter

Prior or current thyroid use

Hx of autoimmune disease

NPO 4 hours before radioiodine administration

Possible interfering medications

Thyroid hormone

Antithyroid med

vitamin/ mineral supplements

Recent X-ray studies with contrast

Gamma camera

Pinhole Collimator

Cold, hot nodule

Multiple nodules

The patient should be in a supine position with the neck comfortably extended.

123I imaging is at 4 hour or at 18 to 24 hours, or both. 50,000 to 100,000 count image or 10-minute acquisition

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Thyroid gland

99mTc-pertechnetate imaging begins at 15 to 20 minutes after injection.100,000- to 200,000-count image in anterior position or 5-minute acquisition

Thyroid and Salivary glands shown

Gamma decay

Energy peak

Technetium-99, (99mTc): 140 keV

Iodine-123 (123I): 159 keV

Window: 20%

Administer 123I (200 to 400 μCi) orally

99mTc-pertechnetate (2 to 10 mCi) intravenously.