The thyroid gland, a butterfly-shaped organ located at the base of your neck, produces hormones that regulate metabolism, energy levels, and body temperature. Sometimes, this gland can develop small lumps or growths known as nodules. When multiple such nodules form, it is referred to as a multinodular goiter. This article explores what a multinodular goiter is and the specific role of ultrasound imaging in its evaluation.
Understanding Multinodular Goiter
A multinodular goiter is characterized by an enlarged thyroid gland containing several nodules, which are usually discrete lumps within the gland’s tissue. These nodules are overwhelmingly benign, or non-cancerous. The development of these nodules is often a gradual process.
Common factors contributing to multinodular goiter include iodine deficiency, leading to thyroid enlargement. Genetic predisposition also plays a role, with a higher incidence observed in individuals with a family history of goiter. While many multinodular goiters remain asymptomatic, larger goiters can cause noticeable swelling in the neck, or pressure symptoms such as difficulty swallowing food or liquids, and occasionally a sensation of breathlessness due to compression of the windpipe.
Why an Ultrasound is Used
Ultrasound imaging is the preferred method for evaluating the thyroid gland and any nodules. This imaging technique uses high-frequency sound waves that bounce off body structures to create real-time images on a screen. A key advantage of ultrasound is its non-invasive nature, and it uses no ionizing radiation.
The absence of radiation makes ultrasound safe for repeated use. Ultrasound provides detailed images that allow medical professionals to accurately identify the number, size, and precise location of nodules. It also helps differentiate between solid nodules, fluid-filled cysts, or mixed components. This detailed visualization is why ultrasound is chosen for initial assessment and ongoing surveillance.
Interpreting Ultrasound Findings
When a radiologist interprets a thyroid ultrasound for multinodular goiter, they carefully examine several characteristics of each nodule. The size and number of nodules are documented, with measurements taken in three dimensions to track any changes over time. The composition of each nodule is also assessed, noting whether it is entirely solid, completely cystic, or has a mixed solid and cystic appearance, with spongiform nodules often appearing as a collection of tiny cysts.
The shape and margins of the nodules provide further clues; a “taller-than-wide” shape or irregular, microlobulated margins can be features that warrant closer attention. Echogenicity describes how bright or dark the nodule appears on the ultrasound image relative to the surrounding thyroid tissue. Hypoechoic nodules may suggest a need for further evaluation.
Calcifications within a nodule are another important feature. Tiny, punctate bright spots called microcalcifications may suggest closer examination. Larger, coarse calcifications or peripheral (rim) calcifications are generally less concerning, though their significance is considered alongside other features.
Blood flow within and around the nodule is assessed using Doppler ultrasound; disorganized or prominent internal blood flow may prompt further investigation. These characteristics are evaluated collectively to guide recommendations for subsequent steps.
What Happens After Your Ultrasound
After your thyroid ultrasound, the radiologist will prepare a detailed report summarizing their findings for your healthcare provider. The report describes the size, number, and characteristics of identified nodules. The next steps are determined based on these ultrasound findings and your overall clinical picture.
Often, blood tests are ordered to assess your thyroid function, including TSH and thyroid hormone levels, to determine if hormone production is affected. If certain nodules exhibit suspicious features on the ultrasound, or if they exceed a particular size threshold (typically greater than 1 centimeter), a fine needle aspiration (FNA) biopsy may be recommended. This procedure uses a thin needle to collect cells from the nodule for microscopic examination, checking for cancerous cells.
For nodules that are clearly benign and do not show concerning features, regular follow-up ultrasounds are typically advised to monitor their size and characteristics, usually every 6 to 18 months. Management strategies vary; if thyroid hormone levels are abnormal, medication might be prescribed. In rare cases where the goiter is large enough to cause breathing or swallowing difficulties, or if malignancy is confirmed, surgical removal of part or all of the thyroid gland may be considered.