THYROID SCANS

This image gives you a map of thyroid FUNCTION.
You can then correlate it to structure to see if there is a non-functional area.
Such areas have a higher likelihood of being a malignancy.
The practical approach is to FNA cold solid nodules and follow with imaging cold cystic nodules.

The key thing before you even look at the pictures though is to look at the TSH.
If it is elevated then you go into the scan room expecting to see one of 4 things:
- Graves
- Thyroiditis...either acute (de Quervain's) with a pain in the neck, or subacute (Hashimoto's)
- Autonomous nodule
- Exogenous T4.

It is terribly difficult to differentiate these differentials clinically but remarkably easy to differentiate these differentials with our scan:
- UNIFORMALLY HOT DOUBLE-LOBED thyroid with no uptake seen elsewhere in the neck is GRAVES.
i.e this is Paget's disease of the thyroid/celebrity thyroid which takes all of the camera's attention and which denies any camera-stealing tracer to go to any other tissue.
- SINGLE LOBE of thyroid means that you are seeing an autonomous nodule with suppression of the rest of the gland
- NO THYROID means either thyroiditis or exogenous T4.

Finally, have a look where the marker is, and decide if thyroid has retrosternal extension, or, if not, if it is enlarged.

Other things to know about thyroid scans:
Almost all of the scans mentioned so far have used Technetium bound to something that homes in on a particular tissue.
Thyroid scans and RBC scans are the exception to this. They both use Pertechnetate [which is just oxidized technetium :) ]

Pertechnetate is taken up by all glands. So, you see all the salivary glands on the scan - these being the parotids at the side up top, the submandibulars at the side down the bottom, and the sublingual gland centrally.