Thyroid Scan - Thyroid Scintigraphy

An ultrasound shows how a thyroid nodule looks. A thyroid scan shows whether it is working.

A thyroid scan, or thyroid scintigraphy, uses a small dose of technetium-99m pertechnetate or iodine-123 to show how the thyroid takes up iodine and which parts of it are overactive or underactive. It answers two questions. Both matter. The first asks why the thyroid is overactive, whether from Graves disease, toxic nodules or thyroiditis. The second asks whether a nodule is hot, producing hormone on its own, or cold. Nodules turn up in up to 65 percent of people and most are harmless, while 5 percent become overactive (Durante and colleagues, JAMA, 2018). A hot nodule so rarely proves to be cancer that guidelines drop the biopsy for it and recommend the scan whenever blood tests show a low TSH. This page explains how the scan works, when it is needed, hot and cold nodules, finding the cause of an overactive thyroid, its role before radioactive iodine treatment and in newborns, preparation and medicines to stop, the scan day, safety, and how patients from abroad arrange the test at Biruni Hospital in Istanbul.

What a thyroid scan is

Thyroid scintigraphy remains the most accurate method for the diagnosis and quantification of thyroid autonomy and the detection of ectopic thyroid tissue (Giovanella and colleagues, European Journal of Nuclear Medicine and Molecular Imaging, 2019).

When a scan is needed

Common reasons

Nodules are common

Few nodules ever need treatment.

Ultrasound finds nodules in more than half of adults, and far more are found now than twenty years ago simply because scans of the neck, chest, spine and carotid arteries done for other reasons pick them up by chance. The great majority stay small and harmless for life. The team looks for the few that matter, those that are cancer, those large enough to press on the windpipe, and those that make too much hormone. The scan answers the third question directly and helps with the first.

That knowledge alone reassures many patients who arrive worried.

Hot and cold nodules

What the patterns mean

American Thyroid Association guidelines advise a radionuclide scan when a nodule is found with a subnormal TSH, and hyperfunctioning nodules rarely harbor malignancy, so they do not need cytologic evaluation (Haugen and colleagues, Thyroid, 2016).

Finding the cause of an overactive thyroid

A radioactive iodine uptake measurement should be performed when the clinical presentation of thyrotoxicosis is not diagnostic of Graves disease, and a scan should be added when thyroid nodularity is present (Ross and colleagues, Thyroid, 2016).

Uptake numbers

Iodine-induced overactivity

Large doses of iodine, from CT contrast or the heart drug amiodarone, make an overactive thyroid show low uptake, which the scan recognizes.

Before radioactive iodine treatment

Radioactive iodine therapy works only if the gland takes up iodine, and the uptake measurement shows how much of the dose it will absorb, which guides both the choice of treatment and the dose.

Newborns and ectopic thyroid

Preparation and medicines

Scan day

Timeline

The nuclear medicine physician often reviews the images the same day and discusses them with you.

Reading the result

Physicians read the scan alongside the ultrasound.

A report that describes a hot area means little unless the nodule it matches on ultrasound is known, so the physician lines up the two, matches each nodule to its pattern and adds the uptake value. The result goes to the endocrinologist or surgeon who requested the scan, and a treatment plan follows. With ultrasound in the same visit, the full answer comes within a day.

Safety

The radiation dose from a technetium thyroid scan is low, about the same as a few months of natural background radiation.

• Allergic reactions to the tracer are extremely rare.
• No sedation or special aftercare is needed.
• The tracer leaves the body within a day, mostly in urine.

Drinking water and emptying the bladder often after the scan speeds clearance.

For patients from abroad

Combining tests

One coordinator from the international patients office handles arrangements from the first message through discharge and answers the same WhatsApp number once you are back home. The office works in English, Arabic, French, Russian, Serbian, Romanian and Spanish and books interpreters for other languages, and it arranges the visa invitation letter, airport transfers, daily transport and accommodation near the hospital. Halal, vegetarian and diabetic meals, a prayer room on site, and a female physician on request wherever the rota allows.

Cost