123-I scan

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What is a 123-I scan?

Iodine (I) is strongly taken up and used by the thyroid tissue in your body. 123-Iodine (123-I) is a radioactive version of iodine. Using this we can see where the iodine can go in your body.

Can I have a 123-I scan if I am pregnant or breastfeeding?

If there is a possibility that you are pregnant or if you are currently breastfeeding please inform the department before your appointment as we will likely have to re-schedule.

Can I bring someone with me?

Whenever possible, you should attend your appointment alone, unless you need a carer to support any additional needs.

How long will my appointment take?

The appointment will take eight hours, but you can leave the department for 6 hours after the first set of imaging. Please read the section ‘What will happen at my appointment’.

What happens before my appointment?

If you are taking thyroxine you will be contacted by the cancer nurses specialists to have two thyrogen injections before your scan. Thyrogen injections stimulate any remaining thyroid tissue to take up iodine while you are taking thyroid hormones like thyoxine.

Do I need to stop my medication?

If you have had a CT scan with contrast or you are taking amiodorone please contact the Nuclear Medicine Department. Do not take any iodine containing supplements before your appointment. You will also need to have a low iodine diet for 2 weeks before your appointment.

What will happen at my appointment?

Firstly, we will place a cannula, usually into a vein in your arm or the back of your hand, where the radioactive tracer is injected. This injection should not have any effect on you. The radioactive tracer will emit gamma rays which will be detected by a piece of equipment called a gamma camera.

The 123-I scan will be carried out six hours after the injection. In the time between the injection and scan you may leave the department and participate in any normal activities, but we ask that you drink plenty of fluid and empty your bladder frequently.

For your scan you are required to lie on the imaging bed to have two set of imaging. The first set of imaging is a whole body scan, the cameras will start over your head and slowly move down your body, which will take about 30 minutes and the second set of imaging is a SPECT / CT, where we do a 3 dimensional (3D) image of a specific area of your body and it can take 30 minutes to one hour. It is important that you remain as still as possible, while relaxed and breathing normally.

All images will be checked before you leave the department. Occasionally images may be repeated or extra images acquired if necessary.

Do I need to undress for the scan?

You will be asked to remove any metallic objects, such as a phone, belts, keys, underwire bra, coins or zips. You may also be asked to change into a gown.

What happens after my appointment?

After the appointment you can resume all usual activities. Eat as normal and keep well hydrated.

If you have young children or pregnant friends / family please limit close contact with them until the following day. You can be in the same room but avoid sitting close to each other for long periods. This is to avoid them receiving any unnecessary radiation exposure.

When will I get my results?

The report will be sent to your referring doctor. They will contact you to discuss the results. If you have any enquiries regarding your results please contact the department where the referral was originally made.

Are there any risks with this procedure?

The radioactive tracer administered will expose you to a small amount of ionising radiation. The risks from this radiation are very low and the benefits of having the results from the 123-I scan greatly outweigh the risk.

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