Thyroid Scan Only

Indications:
  1. To detect hypothyroidism, or hyperthyroidism.
  2. Detection of Metastasis from Thyroid cancer.
  3. Differentiate between benign and malignant tumors.
  4. Detection and function studies of nodules.
  5. Evaluation of function within a hyperthyroid gland.
  6. Detection and localization of benign ectopic thyroid tissue.

Contraindications:
  1. Allergy to iodine.
  2. Recent consumption of iodinated foods.
  3. Continuation of iodinated drugs.
  4. Patient has not discontinued Thyroid medication.

Radiopharmaceutical information:
  • Radiopharmaceutical: Tc-99m Pertechnetate, or I-123 capsule
  • Adult dosing: 3-10 mCi of Tc-99m or 100-300uCi of I-123.
  • Pediatric dosing: not specified
  • Method of administration: IV for Tc-99m and PO for I-123
  • Method of Localization: active transport, Tc-99m trapped, but not organified.
  • Physical Half-life: 6 hours


Patient Preparation:
  1. Discontinue thyroid medication and avoid contrast material, or Betadine.
  2. Refrain from eating seafoods with high iodine content, cabbage, turnips, or kelp.

Equipment Used:
Type of Camera or Probe: LEHR
Collimator used: Pinhole with 3to 6 mm aperture

Acquisition Setup:

Dynamic: View(s)
Matrix:
Time/Frame:
Number of Frames:

Statics: View(s)
Matrix: 128x128
Total Counts or Duration: Anterior, RAO, LAO 250k per view. Procedure will be completed withing 30 minutes.

Whole body: View(s)
Matrix:
Scan Speed:
Start/stop points:

SPECT:
180 or 90 degree configuration
Total Rotation: 180 or 360
Starting point:
Matrix
Time/Azmuiths
Number of Azmuiths:

Procedure:
  1. Patient preparation would include suspension of any meds that can affect uptake, also included ionated foods etc
  2. Establish IV and administer 5mCi of Tc99m pertechnetate.
  3. Imaging 20 after administration, patient is positioned supine with neck hyper extended, collimator is placed so thyroid can occupy 2/3 of FOV.
  4. Views: anterior, RAO, LAO 250K per view.
  5. Utilize two markers, one is placed at the chin and the other at the suprasternal notch.
  6. Move gama camera 10-15 cm away, anterior view is acquired for 250k cts.


Normal Uptake and common variants:
  1. Euthyroid: homogenous uptake of radiotracer.
  2. Left lobe smaller than right lobe or having pyramidal lobe.
  3. Straight or convex outer margins.
  4. Uptake equal to or greater than that of the salivary glands.

Abnormal Uptake and causes:


external image tr012tr125.gif

this image shows uniform increase uptake in both lobes of the thyroid due to Graves Disease

  1. Plummer's disease: autonomous multinodular goiter; nodules, solitary or multiple: can be cold or hot.
  2. Solitary nodules: adenoma, Multiple: Goiter.
  3. Non-visualization of the Thyroid gland caused by subacute thyroiditis.
  4. Graves disease: presents as enlarged thyroid gland, high uptake values.
  5. Hashimoto's thyroiditis: enlarged gland, mottled (checkerboard like) areas of uptake.
  6. Thyroid carcinomas: usually solitary cold nodule. Only 4% show high uptake.

Artifacts:
  1. Compton Scatter
  2. High neck background radiation
  3. High collar metal buttons or chains
  4. Improper collimator
  5. Poor marker placement
  6. Patient movements can blur images

Questions asked in Patient History:
  1. Have you noticed any neck swelling?
  2. Do you have a family history of cancer including thyroid disease?
  3. Any recent weight changes?
  4. Any recent x-ray in which contrast medium was utilized?
  5. Are you taking vitamins with iodine?
  6. Do you experience any discomfort with body temperatures?


References:
abnormal image -->
http://gamma.wustl.edu/tr012te125.html