Thyroid Nodules - How Ultrasound Differentiates Between Benign and Suspicious Nodules
- Dr. Segnini
- 13 hours ago
- 3 min read
A Common Finding:
Thyroid nodules are masses or lumps that form within the thyroid gland, located at the base of the neck. They are extremely common (it is estimated that up to 50-65% of the population may have them), and the vast majority (more than 90%) are benign. Ultrasound is the cornerstone for evaluating them, as it allows us to see what palpation cannot and guides crucial clinical decisions.
Why is Ultrasound the Ideal Technique?
It is the method of choice because:
It does not use ionizing radiation.
It is accessible and inexpensive.
It has high resolution for superficial structures such as the thyroid.
It evaluates real-time characteristics that are key to risk.
It accurately guides fine needle aspiration (FNA) biopsies to obtain samples.
Ultrasound Characteristics: The Language of the Image
The radiologist carefully analyzes each nodule according to a series of visual patterns. This is the essence of the diagnosis:
Characteristics that suggest BENIGNITY:
Simple cyst: Completely anechoic (black in the image), with well-defined edges. Contains only fluid. Almost no risk.
Spongiform: “Honeycomb” appearance, with multiple echogenic (white) microspaces. Very typical of hyperplastic nodules.
Hyperechoic with complete halo: A dark (hyperechoic) nodule surrounded by a clear, uniform ring, which usually indicates that it is encapsulated.
Acoustic shadow macrocalcifications: Large calcifications that cast a dark shadow behind them, often seen in old and degenerated nodules.
Features that suggest HIGH SUSPICION of MALIGNANCY (Cancer):
Solid hypoechogenicity: Being completely solid and darker than the surrounding neck muscle.
Irregular or spiculated margin: Poorly defined edges, with extensions into normal thyroid tissue (like “spikes”).
Microcalcifications: Small (<1 mm) bright white dots, which may correspond to calcium deposits in tumor cells (psammomas).
Taller than wide (non-parallel): A nodule that grows more in depth than in width, extending beyond the transverse plane.
Extratyroid extension: See how the nodule breaks through the thyroid capsule and invades neighboring structures.
The TI-RADS System: Classifying Risk
To standardize findings and recommendations, the American College of Radiology (ACR) created TI-RADS (Thyroid Imaging Reporting and Data System). It assigns points for each suspicious feature and groups nodules into categories:
TI-RADS 1 (TR1): Normal thyroid. No nodules.
TI-RADS 2 (TR2): Benign nodule (e.g., simple cyst). No follow-up needed.
TI-RADS 3 (TR3): Nodule probably benign (e.g., spongiform). Follow-up in 1-2 years.
TI-RADS 4 (TR4): Suspicious nodule, subdivided into 4A (low suspicion) and 4B (intermediate suspicion). FNAB recommended depending on size (e.g., >1.5 cm or >1 cm).
TI-RADS 5 (TR5): Highly suspicious nodule (e.g., with 3 or more malignant features). FNA recommended for smaller nodules (e.g., >1 cm).
What to Do with a Detected Thyroid Nodule?
The workflow is clear thanks to ultrasound and TI-RADS:
1. Complete ultrasound evaluation with all characteristics and measurements.
2. Assignment of TI-RADS category.
3. Recommendation based on category and size:
TR2: Do nothing.
TR3: Follow-up ultrasound.
TR4/TR5: Consider fine needle aspiration biopsy (FNAB) for cytological diagnosis.
4. FNAB (guided by ultrasound) will provide the definitive diagnosis in most doubtful cases.
Conclusion and Key Message
Finding a thyroid nodule is not synonymous with cancer. Ultrasound is a powerful tool that, through systematic analysis of its internal structure, allows us to stratify risk with great precision. Systems such as TI-RADS help to avoid unnecessary biopsies and focus follow-up, ensuring patient safety and optimizing healthcare resources. The ultrasound report, interpreted by the endocrinologist, is the guide for the next step.
thyroid nodule ultrasound
Comments