The thyroid TI-RADS classification is a form of thyroid ultrasound classification. TI-RADS 4a means that a thyroid nodule can be, with a 5%-10% probability of malignancy. It is recommended to do a thyroid puncture biopsy to clarify the benignity and malignancy.
Ultrasound of the thyroid is a simple, practical, and noninvasive test. A thyroid nodule is a common imaging finding on ultrasound. Some of these thyroid nodules are at high risk of malignancy or are even malignant themselves. Therefore, in 2009 Horvath et al. summarized the American College of Radiology Breast Imaging Report and Data System to classify the imaging presentation of thyroid nodules, primarily for assessing the risk of thyroid cancer. Most thyroid nodules are benign and do not require management, but some are at risk for malignancy. Thyroid cancer can be cured if detected early and treated early. Therefore, it is crucial that thyroid cancer is detected early with ultrasound.
Horvath et al. developed the TI-RADS as follows: TI-RADS category 1: normal thyroid; TI-RADS category 2: benign (malignancy rate 0); TI-RADS category 3: benign nodules likely (malignancy rate <5%); TI-RADS category 4: suspicious nodules, which can be divided into 4a (malignancy rate 5%-10%) and 4b (malignancy rate 10%-80%); and TI-RADS category 4: suspicious nodules. 80%); TI-RADS category 5: malignant nodule probable (malignancy rate >80%); TI-RADS category 6: typing includes biopsy-proven malignant nodules.
With the above classification it is clear that TI-RADS4a represents a certain rate of malignancy and therefore further refinement of the thyroid puncture biopsy is recommended.