Everything You Need to Know About Thyroid Scans: Steps and Interpretations
Verified by: Dr. Shreyas Cadabam
Doctors recommend thyroid scans to diagnose conditions such as hyperthyroidism, cancer, and other thyroid growth. Using radioactive iodine, this nuclear medicine scan detects gamma rays emitted from the thyroid. The procedure provides detailed information about the thyroid’s size, shape, position, and function, assisting in identifying thyroid carcinoma or nodules.
This blog covers the essentials of thyroid scans, detailing the steps involved in the procedure and how to interpret the results. You'll learn about the types of thyroid scans, their purpose, and what abnormal results might indicate. Gain a comprehensive understanding of how thyroid scans aid in diagnosing and managing thyroid disorders.
What is a Thyroid Scan?
A thyroid scan is a medical imaging procedure used to evaluate the structure and function of the thyroid gland. The thyroid gland is a butterfly-shaped organ. It is located in the front of the neck, just below Adam's apple.
It plays a crucial role in regulating metabolism by producing thyroid hormones. A thyroid scan in Bangalore is a valuable tool for diagnosing and monitoring thyroid disorders and providing essential information for treatment decisions.
Healthcare professionals with expertise in thyroid disorders will usually choose the specific type of scan and interpret the results. They may be endocrinologists, nuclear medicine specialists, or radiologists.
Types of Thyroid Scans
There are two main types of thyroid scans that include:
1. Radioactive Iodine Scan (RAI)
RAI is the most common type of thyroid scan to evaluate the thyroid’s function. It involves using a radioactive form of iodine, usually iodine-123 or iodine-131.
The patient either swallows a small amount of radioactive iodine or receives it through an injection.
It all depends on the specific test. The thyroid gland takes up iodine to produce thyroid hormones, so the radioactive iodine accumulates in the thyroid tissue.
In this type of thyroid scan, a special camera, known as a gamma camera, is used to perceive the radiation emitted by the thyroid. The Radioactive Iodine Scan provides information about the thyroid gland’s size, shape, and function.
It helps to detect thyroid conditions, such as hyperthyroidism (overactive thyroid), hypothyroidism (underactive thyroid), and thyroid nodules.
2. TU or Thyroid Ultrasound
This type of thyroid scan uses a non-invasive imaging technique that uses high-frequency sound waves to create images of the thyroid gland. It helps to evaluate the structure of the thyroid and identify any abnormalities, such as nodules, cysts, or tumours.
Thyroid ultrasound can help distinguish between solid and fluid-filled masses in the thyroid, aiding in diagnosing thyroid conditions.
The choice between these two types of scans depends on the specific clinical question the healthcare provider is trying to answer. In some cases, healthcare professionals combined use both scan types to get a complete assessment of the thyroid gland.
Why is Thyroid Scan Performed?
A thyroid scan is performed for several important reasons:
- Evaluate Thyroid Nodules or Goiter: The scan helps in assessing the size, shape, and nature of thyroid nodules or an enlarged thyroid (goitre). It provides detailed images that can reveal whether these growths are benign or potentially malignant.
- Diagnose Overactive Thyroid Gland (Hyperthyroidism): The test identifies the underlying causes of hyperthyroidism by showing how much radioactive iodine the thyroid absorbs. This helps in diagnosing conditions like Graves' disease or toxic multinodular goitre.
- Check for Thyroid Cancer: Although less common, a thyroid scan can be used to detect thyroid cancer. However, other diagnostic tests, such as fine-needle aspiration biopsy and ultrasound, are typically more accurate and preferred for this purpose.
How Does a Thyroid Scan Work?
You will take a pill with radioactive iodine. After swallowing the pill, there is a waiting period for the iodine to accumulate in your thyroid. The first scan is done 4 to 6 hours later, with a second scan possibly 24 hours after the first. In some cases, technetium is used for imaging instead of iodine.
Once the radioactive iodine is absorbed, you will lie on a movable table with your neck and chest positioned under a scanner. The scanner detects gamma rays emitted from the iodine. It's essential to lie still during the scan for clear imaging.
The scanner then transmits the data to a computer, which generates images of your thyroid, showing any nodules or other abnormalities that have absorbed the iodine.
Preparing for Your Thyroid Scan
Preparing for a thyroid scan involves several important steps to ensure accurate results. Here are some key guidelines to follow:
- Fasting Instructions: Do not eat anything after midnight before your morning scan.
- Iodine Disclosure: Let your healthcare provider know if you're taking any iodine-containing products, including certain medications and supplements.
- Health Notifications: Inform your provider if you have diarrhoea (affects iodine absorption), had a CT scan with iodine contrast recently (within the last two weeks), dietary iodine imbalances.
- Metal Items: Remove all jewellery, dentures, and other metal objects to prevent interference with the scan.
Interpretation and Diagnosis of Thyroid Scan
Based on the scan results, healthcare providers can make various assessments:
Hyperthyroidism: If the thyroid gland takes up too much radioactive iodine, it indicates overactivity.
Hypothyroidism: If the thyroid takes up too little radioactive iodine, it suggests underactivity.
Thyroid Nodules or Tumours: The scan can also help identify the presence of thyroid nodules or tumours.
Thyroiditis: In cases of thyroid inflammation (thyroiditis), the scan may show varying patterns of iodine uptake.
Common Abnormalities Detected in a Thyroid Scan
When interpreting the results of a thyroid scan, several types of abnormalities might be detected, each indicating different potential issues:
- Enlarged Thyroid or Misalignment: An enlarged thyroid or one pushed off to one side could indicate a tumour.
- Nodules: Nodules that absorb different amounts of iodine appear darker or lighter on the scan. A lighter nodule (cold nodule) hasn't absorbed much iodine and may suggest a thyroid problem. Darker nodules (hot nodules) have absorbed more iodine and may indicate an overactive thyroid.
- Radioiodine Uptake Percentage: The scan also shows the percentage of iodine collected in your thyroid. Excessive iodine uptake may indicate an overactive thyroid, while insufficient uptake could be due to inflammation or other thyroid damage.
The radioactive iodine used in these scans emits minimal radiation and is considered safe for diagnostic purposes.
Risks and Considerations for Thyroid Scan
Although any exposure to radiation has potential side effects, the radioactivity used in a thyroid scan is very low, with no documented adverse effects.
Pregnant or breastfeeding women should refrain from having this test. Address any concerns with your healthcare provider.
The radioactive iodine will leave your body through your urine. Due to the low dosage, special precautions like flushing twice after urinating are generally unnecessary for 24 to 48 hours post-test. It's best to ask your healthcare provider or the radiology/nuclear medicine team if any specific precautions are needed.
Ensuring Accurate Thyroid Scan Assessments at Cadabam's Diagnostics
Thyroid scans are essential for evaluating the function and structure of the thyroid gland. Cadabam's Diagnostics offers top-notch thyroid scan services, ensuring accurate and comprehensive assessments.
At Cadabam’s Diagnostics, our experts use cutting-edge technology to ensure the highest standards of care, offering reliable and precise results. For a trustworthy thyroid scan in Bangalore, rely on Cadabam's Diagnostics. Take control of your health—schedule your thyroid scan with us today and benefit from our dedication to your thyroid health.