PARATHYROID SCAN PROCEDURE

TECHNOLOGISTNUCLEAR MEDICINE DEPARTMENT

SABAH WOMEN AND CHILDREN HOSPITAL

Where Are The Parathyroid Glands?

Typically there are four parathyroid glands located alongside and sometimes within the thyroid gland.

There are usually two parathyroid glands near the left lobe of the thyroid and two near the right lobe.

They are small, oval-shaped glands each approximately 6 x 4 x 2 mm and weighing approximately 30–50 mg., (about the size of a pea).

Nuclear medicine has an active role in the management

of patients with hyperparathyroidism by identifying the sites of excess parathyroid hormone production, that is, the localization of a probable adenoma in a patient with hyperparathyroidism.

Parathyroid adenomas are found in diverse localizations alongside, behind, and within the thyroid as well as in areas somewhat distant from the thyroid such as high or low in the neck or mediastinum. For this reason, there is a significant need for a method to accurately and non invasively identify the location of excess parathyroid hormone production.

It is important to include the entire chest in the imaging field in all parathyroid imaging protocols for evaluation of potential ectopic sites.

Parathyroid Study..

Localization of hyperfunctioning parathyroid tissue

(adenoma/ hyperplasia) in primary hyperparathyroidism is useful before surgery to help the surgeon localize the lesion, thus shortening the time of the procedure.

Localization of hyperfunctioning parathyroid tissue in patients with persistent or recurrent disease

Indication

Pregnant women

Contraindication

Discontinuation of breast feeding for nursing mothers

for 24 hours after imaging.

Precaution

Patient might be advised by Medical Officer to discontinue usage

of iodide-containing medications that can cause iodine saturation. Radiological studies with iodine-containing contrast media should

be avoided 4 weeks prior to the parathyroid scintigraphy. Treatment with Carbimazole or Propylthiouracil should be with

held 3 days prior to the scan. Thyroid replacement hormone should be discontinued for 2 weeks

prior to scan. Whereas for secondary hyperthyroidism, active Vitamin D should

be withheld for at least 1 week, native Vitamin D for 4 weeks and calcimimetics for 2 weeks prior to the scan (need to be discussed with Nuclear Medicine Specialist/Nephrologist)

Patient Preparation

99mTechnetium-sestamibi adult: 18-22 mCi 99mTechnetium-tetrofosmin adult: 18-22 mCi 99mTechnetium-pertechnetate adult: 2-10 mCi Child: As per body weight (Refer to Gilday’s Chart) Technique of administration: Intravenous Injection

Radiopharmaceutical

Protocol

Washout

Dual phase parathyroid scintigraphy exploits the different washout timing that some radiotracers show in thyroid and parathyroid tissues: to find parathyroid hyperfunctioning tissue, washout timing of radiotracer from the parathyroid must be slower than from thyroid tissue.

Subtraction99mTc-sestamibi is myocardial perfusion tracer and is taken up not only by the hyperfunctioning parathyroid glands but also by thyroid tissue. Hence, the necessity of comparison with a second tracer, which is taken up by the thyroid gland only, such as 99mTechnetium-pertechnetate. The distributions of the 2 tracers can be visually compared and, afterwards, the thyroid scan can be digitally subtracted from the parathyroid scan to remove the thyroid activity and enhance the visualization of parathyroid tissue.

PHILIPS Dual-head Gamma Camera Low Energy High Resolution (LEHR) collimator High Energy Low Resolution (Pinhole) collimator

Instrument

Make sure the Gamma Kamera room is ready. Call Patient in the post-injection room. Explain patient about the procedure. Position the patient on the table in the supine position

with a pillow positioned under the shoulders which allow the head to drop back and extends the neck. Secure the head so that it does not move from side to side.

Make sure the patient is comfortable and cover the patient with blanket before starting the procedure to ensure patient is warm.

Tell the patient not to move while performing the scan.

Procedure

Static ANT/POST 20 mins after injection of

Tetrofosmin SPECT Pinhole Static Tetrofosmin 60 mins after inject Pinhole SPECT Static Tetrofosmin delayed 2 hours after inject SPECT Pinhole [Delayed 3 hours after inject if necessary] Static Pinhole SPECT

Washout Procedure

If needed

If needed

If needed

If needed

Static ANT/POST 20 mins after injection of Tc99m SPECT Pinhole Pinhole Tetrofosmin 60 mins after inject Static SPECT Static Tetrofosmin delayed 2 hours after inject SPECT Pinhole [Delayed 3 hours after inject if necessary] Pinhole Static SPECT

Subtraction Procedure

If needed

If needed

If needed

If needed

After the completion of the scan, inform the Medical Officer in

charge to review the scan images. Be ready to repeat scan or perform additional scan if ordered

by the Medical Officer in charge. Assist the patient to get up and ask the patient to have rest

while waiting in the post-injection room. Remind patient to take plenty of water and to keep at least 1-2

meter away from children and pregnant ladies for at least 6 hours from the time of the radiopharmaceutical injection.

Inform and pass the “Penilaian Selepas Skan Radionuklid” form to the Nurse in charge at the counter or injection room regarding the patient release.

Proceed to image processing by referring to the Standard Operating Procedure of Parathyroid Scan Processing.

Cont..

International Atomic Energy Agency: Nuclear Medicine

Resources Manual, 2006 SNM Practice Guideline for Parathyroid Scintigraphy 4.0 2009 EANM Parathyroid Guidelines Distance Assisted Training Programme for Nuclear

Medicine Technologists: Parathyroid Imaging, Version 3.1

Nuclear Medicine Technology and Techniques by Donald R. Bernier, Paul E. Chstistian, James K. Langan

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