Imaging to Diagnose Thyroid Disorders

Certain thyroid disorders like lump in the thyroid gland (thyroid nodule) and thyroid hormone excess (Hyperthyroidism) requires imaging evaluation which helps in indentifying the cause of problem and guides further course of treatment in a patient. Thee imaging tests are important to know the location of the disease and it the issue can led to other complications in the body or not. Following are few of the tests that are needed to diagnose thyroid disease.

• Thyroid Ultrasound: It is a non-invasive and painless procedure which uses sound waves to generate images of the thyroid gland. It provides the best information about the shape and structure of thyroid nodules, thus differentiating between fluid filled cyst, benign (non-cancerous) or cancerous lesions. It may also be used as a guide in performing a fine-needle aspiration biopsy (FNAB).
• Thyroid Colour Doppler: This technique is similar to thyroid ultrasound and in addition, provides information about enhanced blood supply of thyroid gland or thyroid nodule which helps in differentiating hyperthyroidism (Grave’s disease) from other causes of thyroid hormone excess. This imaging technique is more useful where thyroid nuclear scan is not available.
• Thyroid Scan: It refers to the Technetium nuclear scan which helps in differentiating the hyper functioning thyroid gland from normal thyroid and also useful in evaluation of thyroid nodules. During this test, ^99mTc-Pertechnetate dye is injected into a vein in arm and a special camera produces an image of thyroid on a computer screen.

What do the tests show? How are the imaging reports interpreted to highlight thyroid issues?

A high uptake of radio-isotope indicates that thyroid gland is producing excess of thyroid hormones. The most likely cause is either Graves’ disease or hyper functioning nodules (hot nodules).

Cold nodules are non-functioning and appear as defects or holes in the scan. Hot nodules are almost always noncancerous, but a few cold nodules are cancerous.

Sometimes, patient may have a thyroid scan as part of a radioactive iodine uptake test. In that case, the orally administered radioactive iodine is used to image thyroid gland.

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