Parathyroid: Dual Isotope

Indications:
  • Detection and localization of primary and secondary parathyroid cancer.
  • Identification of single adenomas, multiple adenomas or gladular hyperplasia in patients with newly diagnosed hypercalcemia and elevated parathyroid horomone levels.
  • localization of cancer for surgery candidates.
  • Localization of parathyroid tissue after surgery for persistant or recurrent hyperparathyroidism.
Contraindications:
  • Patient on calcium medications.
  • Patient on thyroid medications and/or recieved recent iodine contrast studies (patient should be off thyroid medications and contrasts for 5-10 days).
  • Patient too agitated or prone to movement.
  • patient is clausterphobic.
Radiopharmaceutical information:
  • Radionuclide: Tc-99m, Tl-201 (not used anymore), I-123
  • Radiopharmaceutical: Pertechnitate, Sestamibi, I-123, thallous chloride. Can be given as a sestamibi/pertechnitate combination or as a sestamibi/I-123 combination
  • Adult dosing: Pertechnitate 5-12 mCi, 1-123 .2- .3 mCi, Sestamibi- 16-30 mCi, thallous chloride- 2-3 mCi.
  • Pediatric dosing:
  • Method of administration: Pertechnitate- iv, Tl-201- iv, Sestamibi- iv, I-123- PO
  • Method of Localization: Pertechnitate- active transport, Sestamibi- passive transport
  • Physical Half-life: Tc-99m- 6 hours, I-123- 13.2 hours, Tl-201- 73 hours

Patient Preparation:
  • Identify the patient. Verify doctors order
  • explain the procedure and the need to remain still during aquisitions
  • Palpate neck to localize any abnormal parathyroid or thyroid tissue
Equipment Used:
Type of Camera or Probe
Collimator used: Pinhole collimator or LEAP, or LEHR. Pinhole is preferred.

Acquisition Setup:

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

Statics: View(s)
Matrix: 128x128x8 or 64x64
Total Counts or Duration:1000k or 300-900 sec/images

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

SPECT:
180 or 90 degree configuration
Total Rotation: 360 degrees
Starting point: Centered on ROI
Matrix:128x128
Time/Azmuiths: 20-25 sec/stop
Number of Azmuiths: 64 stops

Procedure:
  • Place the patient in a supine position, pillow under shoulders, head back, neck extended
  • Position camera anterior over extended neck and mediastimum
  • Remove any metal the patient is wearing
  • Inject Tl-201
  • within 2-3 minutes of injection, obtain a 300 sec image, preferabley with a pinhole collimator looking for focal u[take between the heart and the thyroid.
  • Immidietley follow the image with a 900 sec image of the thyroid centered in the field of veiw.
  • Immidietley follow the image with an injection of 5-10 mCi of Tc-99 pertechnitate. Wait 5 minutes.
  • Obtain a 900 second image of the thyroid
  • run the subtraction program if necessary to separate Tl-201 accumilation from Tc-99 pertechnitate trapping.
Normal Uptake and common varients:
  • No increased Tl-201 activity within or outside normal thyroid tissue.
  • Normal parathyroid tissue does not accumulate Tl-201
Abnormal Uptake and causes:
  • Areas of increased Tl-201 within and outside normal thyroid tissue
Artifacts:
  • Patient movement
  • Ectopic tissue not visualized
  • May not visualize abnormal tissue that is less than 300mg in size


Questions asked in Patient History:
  • Do you have hx or family hx of para thyroid disease?
  • Do you have hx or family hx of cancer?
  • Do you have osteoporosis?
  • Are you sensitive to pain?
  • Do you have kidney disease or stones?
  • Have you had recent thyroid surgery?
  • Have you noticed any swelling or tenderness in your neck?
  • Have you had any recent iodine contrast studies?
  • Have you had any related studies?
  • What medication are you taking?
  • Do you have any recent lab results, particularly Ca and PTH levels?
  • Any other specific questions you want to bring up?
  • Are you pregnant or breast feeding?
References:
Nuclear Medicine Technology Procedures and Quick Reference by Pete Shackett
Society of Nuclear Medicine: Parathyroid imaging