Letter to the Editor: “Ultrasound malignancy risk stratification of thyroid nodules based on the degree of hypoechogenicity and echotexture”
by Maria Alejandra Rueda M.D., Sergio Valencia M.D. M.Sc., Julian Guerra M.D, Nelson Bedoya M.D Radiologist (mariarueda91@gmail.com)
Ultrasound malignancy risk stratification of thyroid nodules based on the degree of hypoechogenicity and echotextureDear Editor,
We have read with great interest the article entitled “Ultrasound malignancy risk stratification of thyroid nodules based on the degree of hypoechogenicity and echotexture” by Lee et al [1]. In this study, it is suggested that the lexicon of nodule echogenicity and echotexture is one of the major differences among various risk stratification systems of thyroid nodules. Nonetheless, risk stratification guidelines of thyroid nodules, such as The Thyroid Imaging Reporting and Data System (TIRADS), The American Thyroid Association (ATA) guidelines and the British Thyroid Association (BTA) guidelines have all acknowledged hypoechogenicity to be an important predictor of malignancy. However, isolated suspicious ultrasound features cannot predict malignancy risk, this is why a multivariate analysis would have been necessary for this study to evaluate all possible interactions between high-risk malignancy features, and elucidate the true predictive value of hypoechogenicity and the authors’ suggestion of stratifying it in mild, moderate, or marked hypoechogenicity [2, 3].
In this study, there was no significant difference in malignancy-risk between markedly and moderately hypoechoic nodules, however, there was a difference in malignancy risk between markedly and moderately hypoechoic nodules and mildly hypoechoic nodules. These findings, strengthen the fact that there is no need to sub-classify the degree of hypoechogenicity given those classification systems such as TI-RADS use hypoechoic vs very hypoechoic nodules, in which the strap muscles are used as the basis for comparison with good sensitivity and specificity when using all other sonographic features [4]. Although the two readers had a substantial agreement for the four categories of iso- or hyperechoic, mild, moderate, and marked nodule echogenicity, evidence shows that more than two radiologists are needed to perform adequate studies of clinical imaging [5].
Finally, the authors mentioned that the diagnosis of malignant or benign were performed by multiple methods: cytology, histopathology of the biopsy, and histopathology after surgery. Having this information, it is interesting to know the diagnostic performance of the cytology on the patient that had surgery.