Methods for diagnosis of the thyroid gland cancer:
- medical history review;
- physical examination (palpation);
- ultrasound;
- fine needle aspiration biopsy;
- radioisotope scanning;
- MRI (magnetic resonance imaging) ;
- CT (computed tomography).
Over the past 30 years, there has been an increase in the number of people diagnosed with thyroid cancer. It is attributed to the wide use of imaging studies that detect thyroid nodules.
Family History
If you have a family history of thyroid cancer, the doctor will test your blood calcium (calcitonin) levels. An elevated level of calcitonin (a hormone vital to calcium and phosphorus metabolism) can indicate cancer.
Examination of the thyroid for nodularity
The very first step in the thyroid cancer diagnosis is an examination. Palpation of the thyroid gland can be carried out by both family doctor and endocrinologists. It is the fastest and easiest method of analysis, preceding the laboratory studies and imaging tests. The doctor will “feel” your neck, which may require you to swallow the saliva, flex and bend your neck.
During palpation the endocrinologist checks:
- the consistency of the gland tissues;
- presence of nodes;
- size of nodes (if any);
- the size of the gland (it consists of 2 lobes, the size of which usually range from 5 to 8 cm);
- the size of the lymph nodes.
An increase in the size of the thyroid gland may indicate a number of diseases, especially when hyperplasia is more than 10% of the norm for this age group. A healthy thyroid is estimated to be 10 - 20 grams.But some increase in the mass of the gland occurs during puberty, and in women - during pregnancy.
However, the regular size of the thyroid gland does not yet guarantee the absence of pathological changes, so preventive ultrasound examinations in people at risk should be performed.
Ultrasound examination of the thyroid gland is a basis for cancer diagnosis.
Ultrasound of the thyroid gland is a simple procedure that does not require any preliminary preparation and contraindications.
Ultrasound diagnosis provides a 100% guarantee of determining changes in the gland tissues.
If necessary, it can be supplemented with Doppler sonography of the gland vessels. This combination of techniques makes it possible to give more information on the tumor without additional radiation exposure (for example, in the case of PET-CT) of a patient.
As a result of ultrasound, the doctor determines: the dimensions of the gland, the tissue structure, and also studies the tumor (its size, shape, echogenicity). Also, the doctor can assess the condition of the lymph nodes of the region.
A biopsy of the thyroid gland. Types and accuracy.
The actual diagnosis of thyroid cancer is made with a biopsy, in which cells from the suspicious area are removed and looked at under a microscope.
When cancer suspected, it is essential to identify a tumor accurately. For this purpose, a Fine Needle Aspiration (FNA) Biopsy is performed, for which needles with a diameter of 23-21G (0,6 - 0,8 mm) are used.
A fine needle biopsy was first introduced in the USA and Canada. Now - it is used all over the world as the least traumatic and more informative method of biopsy.
Cytological research determines the nature of tumor and autoimmune thyroiditis.
Biopsy of the gland is carried out under the ultrasound supervision. The doctor has the opportunity to take a tissue sample even from a small-sized formation. This technique improves not only the quality and accuracy of sampling but also reduces the likelihood of blood and cystic fluid entering the study material.
The process of tissue sampling for analysis with fine needle biopsy reminds of taking blood from the vein. To ensure the accuracy of the result, you need to get enough tissue, for which the doctor can make several injections.
The sample is transferred for an examination to the cytologist. The biopsy procedure does not require special preparation from the patient.
FNA biopsy of the thyroid gland is 98% accurate and is considered the only reliable method of diagnosis apart from surgical intervention.
A biopsy of the thyroid gland is an absolutely safe procedure performed under local anesthesia and does not have any significant complications.
There may be a slight pain in the neck the next few days after and a small hematoma at the site of the injection.
Puncture biopsy is used not only to diagnose thyroid cancer but also to observe the dynamics of patients on treatment, to determine indications for surgical intervention and as a treatment for solitary thyroid cysts.
Biopsy reveals:
- benign changes (non-tumor diseases of the gland);
- malignant changes (carcinomas, metastases, lymphomas);
- changes, with suspected malignancy (neoplasia);
- insufficient for research material.
If the diagnosis is not definite after an FNA biopsy, a doctor might need a more involved biopsy to get a better sample. It might include a core biopsy using a larger needle (2,5 mm), a surgical biopsy to remove the nodule, or a lobectomy (partial removal of the gland). Surgical biopsies and lobectomies are done in an operating room under general anesthesia.
Radioiodine scan of the gland (Scintigraphy)
Scintigraphy is one of the widely used methods for diagnosing thyroid diseases, which is performed by radioactive isotopes (iodine 123 and 131, technetium 99). The use of radioisotope scanning makes it possible to evaluate the functioning of the gland, to detect cell malignancies or vascular changes.
Because medullary thyroid cancer cells do not absorb iodine, radioiodine scans are not used for this cancer.
The technique is completely safe for the body (for example, with the help of the technetium isotope it can be performed even for infants), but some contraindications limit the possibilities of using it for specific groups of patients (pregnant women, nursing mothers).
Scintigraphy based on the principle of the glands ability to absorb and excrete iodine (as well as other isotopes), which is used for research. The thyroid gland accumulates much more iodine than any other organ in our body because it produces iodine-based-hormones (e.g., thyroxine).
The radioisotopes then leave the body with feces and urine.
For this test, a small amount of radioactive iodine is swallowed or injected into a vein. Over time, the iodine is absorbed by the thyroid gland (or thyroid cells anywhere in the body). A special camera captures images and measures the amount of dye the gland (nodules) absorbs.
Normal and abnormal test results are reported as functioning (standard), cold (that do not accumulate radioisotopes), or hot (overactive). Cold thyroid nodules indicate a disease or nodular goiter and need further evaluation.
Preparatory recommendations for the procedure:
- to stop taking iodine-containing medications (if they were not prescribed for treatment),
- to avoid other studies with contrast (renal urography, MRI with additional contrast).
Advantages and differences of CT and MRI of the thyroid gland
In the complex diagnosis of the thyroid gland, both computer and magnetic resonance imaging are performed. The basis of these reliable high-precision methods is X-ray radiation and nuclear magnetic resonance.
CT helps the doctor assess the morphological changes in the thyroid gland. The most common indication for computed tomography is the deep localization of tumors, inflammatory processes, and organ damage.
The main contraindication for both methods is pregnancy.
MRI of the thyroid gland allows you to obtain a 3-dimensional image. It gives precise information about the size, anatomical structure, and location of the neck organs and tissues. This data is essential for planning the surgical treatment.
MRI is more informative compared to CT but also is more expensive.
Other methods
PET-CT. Positron emission tomography can be useful if thyroid cancer doesn’t take up radioactive iodine. In this situation, the PET scan may be able to tell whether cancer has spread.
Laryngoscopy - a larynx examination with a thin tube, a light and a lens on end. Since thyroid tumors can sometimes affect the vocal cords, the doctor (before the surgery) may check if they are moving normally.
The frozen-section biopsy - intraoperative cytological study (cryosection). It is the "quick biopsy" performed during the surgery. A doctor can determine the structure of cells and tissues in the thyroid literally in a matter of minutes. It allows surgeons to decide on further thyroid surgery tactics while the patient is still in the operation room.