18-20 Week Screening Pregnancy Ultrasound
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A parathyroid MIBI scan is used in nuclear medicine to look at possible problems involving the parathyroid gland(s).
The parathyroid scan uses the radioisotope, technetium-99m sestamibi (or MIBI), which is injected into the body and absorbed by the overactive parathyroid mitochondria. A hyperactive gland is picked up by the scan on the images taken by a gamma camera.
In some cases, another radioactive material (sodium pertechnetate) is given before the MIBI, so that the thyroid gland alone can be identified. This allows the position of the parathyroids to be assessed in relation to the thyroid gland.
Due to the radioactivity of the MIBI scan, the study may not be suitable for pregnant women. The benefit versus risk should be discussed with the nuclear medicine specialist.
If the patient is unable or not willing to remain still for a prolonged period of time or is claustrophobic, you may need to consider another procedure, such as an ultrasound looking for enlarged gland/s in the neck or a four-dimensional computed tomography.
Both the relative contraindications above will interfere with thyroid gland uptake, making it difficult to obtain a technetium subtraction image, where the abnormal parathyroid gland(s) can be separated from the thyroid gland.
Generally, there are no adverse reactions. However, on rare occasion the patient may experience a metallic taste that lasts a few moments.
Very rarely a patient could experience:
Women who are breast-feeding and people who are the primary or sole carer for small children may need to make special preparations after the test to stop breast-feeding for 4 hours,1 and to avoid close contact with young children due to the small amount of radioactivity released for 4 hours1 after the test. See InsideRadiology: Nuclear Medicine for further information about the precautions to take with nuclear medicine studies for breast-feeding patients and those in close contact with children.
1. ARPANSA – Radiation Protection Series No 14.2. Date of publication: 8 August 2008 pages 31-32.
Page last modified on 18/5/2018.
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