MIBG SCAN

This is used to diagnose phaeochromocytoma.

The phaeo will be best seen from the back of the patient because the liver and spleen are shining bright from in front.

The things to know so as to understand this scan are:
i) MIBG is made by the body into NA. Therefore it will be seen in tissues that have NA in them - adrenals, heart and NAsopharynx.
ii) It is urinary excreted (which is why you do urinary catechols when looking for a phaeo)- therefore you will see hot bladder and bowel.
iii) It has I in it and so will be taken up by any tissues that are iodine-avid - thyroid, salivary glands, spleen, liver.

Preparations for the scan are critical:
1. If you have iodine in the body then that will be used to make NA in preference to the MIBG. Therefore, no contrast.
2. You don't want the thyroid sucking up all the MIBG. So, give Potassium Iodine for 2/7 before and on the 2 days of image-taking
3. You don't want to stop MIBG being taken up by neuroendocrine tissue. Therefore, don't use:
- cocaine/amphetamines/cough mixtures
- reserpine
- tricyclics
- calcium channel blockers
- labetalol (all the other alpha blockers and beta blockers are OK).