The document outlines the use of various radiopharmaceuticals, mainly iodine isotopes and technetium-99m, for thyroid scanning procedures. It details indications for their use, administration methods, contraindications, patient preparation, and typical procedural protocols. Additionally, it describes normal and abnormal results from the scans, including implications for conditions such as hyperthyroidism, hypothyroidism, and thyroid cancer.

1. Thyroid: Scan
Ahmed abu hassnah

2. RADIOPHARMACY
Radionuclide
• 123I t1/2: 13.1 hours
Energies: 159 keV
• 131I t1/2: 8.1 days
Energies: 364 keV
• 99mTc t1/2: 6 hours
Energies: 140 keV

3. Radiopharmaceutical
• 123I and 131I as capsules
• 99mTcO4 − (pertechnetate)

4. Adult Dose Range
• 131I: 1μCi −10 mCi depending on
patient and reason for scan. Usually
5–30 μCi for uptake and scan, 2–5 mCi
for whole body imaging and/or
treatment of patients.
• 123I: 100–450 μCi.
• 99mTcO4 −: 2–10 mCi.

5. Method of Administration
• 123I and 131I capsule Oral (PO).
• 99mTc by intravenous injection.

6. INDICATIONS
• Evaluation of thyroid anatomy, e.g.,
position, goiter (enlarged gland due to
inadequate iodine supply), surgery, cold
or hot nodule(s).
• Detection and evaluation of hyperthyroidism
and hypothyroidism.

7. • Detection and localization of metastases
from thyroid cancer.
• Differentiation of benign from malignant
nodules.
• Detection, localization, and evaluation of
independent functioning nodule(s).
• Evaluation of heterogeneity of function
within a hyperthyroid gland.

8. • Detection and localization of benign ectopic
thyroid tissue.
• Evaluation of abnormal thyroid serum
laboratory results.
• Evaluation of subclinical (before appearance
of typical symptoms of disease) and subacute
(between acute and chronic) disease processes,
e.g., toxic goiter, thyroiditis.

9. • Evaluation of thyroid because of
abnormal findings on other diagnostic
images, e.g., US, x-ray images, PET,
MRI, CT.

10. CONTRAINDICATIONS
• Allergy to iodine if that is being used.
• With iodine, interfering recent contrast
studies.
• With iodine, patient has not discontinued
thyroid or interfering medication, vitamins,
or iodinated food products.

11. PATIENT PREPARATION
• Identify the patient. Verify doctor’s order.
Explain the procedure.
• Patient to discontinue thyroid medications
and avoid contrast material, Betadine®, or
amiodarone.
• Refrain from eating foods containing iodine
such as cabbage, turnips, greens, seafood, kelp,
or large amounts of table salt.

12. • 123I and 131I:
Patient will be returning at 4 to 6 hours
and 24 hours for scan.
131I: Patient will usually be returning
at 24 hours and beyond for imaging.
This iodine is not routinely used for
uptake and scans.

13. PROCEDURE (USUALLY TWO PARTS; TIME: ~40
MINUTES)
99mTcO4−
• Administer injection to patient; wait 15 to 20
minutes before imaging. Give patient water
(optional lemon to clear salivary glands).
• Place patient in supine position with pillow
under shoulders and chin up.

14. •Using a pinhole collimator if
available,obtain anterior views with
and without markers as per protocol,
then RAO and LAO.
• are optional images if a pinhole
collimator is not available.

15. 123I Capsule
• without injection. mage 50,000 to 100,000 counts
or 8 to 10 minutes per image. Images can be taken
from 3 to 36 hours after administration of capsule
(usually at 4–6 hours or 24 hours).
131I Capsule
• without injection. Usually used to locate residual
and recurrent cancers. 24-, 48-, and 72-hour pictures
may be the most useful. Collect 100,000 counts over
thyroid and whole body if cancer is suspected.

16. NORMAL RESULTS
• Euthyroid: Homogeneous uptake of radiotracer.
• Left lobe smaller than right lobe or having pyramidal
lobe.
• Straight or convex outer margins.
• Uptake equal to or greater than that of salivary
glands (water or lemon given to reduce salivary
uptake).

17. • 99mTc also shows in soft tissue, brain,
stomach mucosa, nasopharynx, bladder.
• 123I and 131I will present in nasopharynx,
salivary glands, stomach, colon, bladder,
lactating breasts.
• The test is usually performed in conjunction
with the thyroid uptake test.

20. ABNORMAL RESULTS
• Plummer’s disease: Autonomous multinodular
goiter; nodules, solitary or multiple: cold and/or
hot (solitary: adenoma, thyroiditis; multiple:
goiter).
• Non visualization of thyroid gland caused by,
e.g., sub acute thyroiditis, patient on
contraindicated medications.

21. • Graves’ disease: Enlarged gland, high
uptake (LATS [long-acting thyroid
stimulator, an autoantibody]).
• Hashimoto’s thyroiditis: Enlarged gland,
mottled.
• Thyroid carcinoma: Usually solitary cold
nodule (4% show high uptake).

22. • Cold nodule on iodine scan can be clarified by
99mTc O4:
− scan Cold on 99mTc O4.
− scan is nonvascular and more than likely
benign though not always.
− scan is vascularized and more likely to be
malignant (20% chance of carcinoma).
Usually followed by biopsy and/or surgery.