https://www.snmclub.com/presentation Nuclear Medicine - Thyroid - Procedure/Scan Ahmed abu hassnah

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.