(Ultrasound Review) Color Doppler cannot be used to differentiate benign and malignant solid thyroid nodules, according to radiologists at Brigham and Women’s Hospital in Boston. However, they demonstrated that 42% of solid hypervascular thyroid nodules are likely to be malignant.
Research published in Journal of Ultrasound in Medicine described the size, and ultrasound and fine needle aspiration (FNA) findings for 254 thyroid nodules. Ultrasound was performed using high-frequency linear array transducers (7-15 MHz). Grayscale characteristics were classified into six categories that described the percentage of cystic versus solid components. "The color Doppler appearance of each nodule was graded from 0 for no visible flow through 4 for extensive internal flow," they reported.
Cytologic or pathologic correlation found that 12% of nodules were malignant and 70% were benign. Color Doppler showed extensive internal flow in 44% of malignant nodules and 14.7% of benign nodules. There was no significant difference in nodule size comparing malignant and benign nodules. Nodules were solid in 40.1% of the malignant nodules and 10.2% of the benign nodules. When many nodules were present they used color Doppler to direct FNA sampling toward the nodule with extensive internal flow, which had a higher likelihood of malignancy.
The authors concluded that although sonography showed solid hypervascular thyroid nodules had a higher likelihood of malignancy, this is not a definitive finding, as 14% of solid nodules without increased vascularity also were malignant.
"In particular, malignant nodules cannot be distinguished reliably from benign nodules on the basis of the sonographic appearance (cystic versus solid), color Doppler characteristics, or both," they wrote.
"In conclusion, solid hypervascular thyroid nodules have a higher risk of malignancy than partially cystic or nonhypervascular lesions. However, the color Doppler characteristics of a thyroid nodule cannot be used to predict or exclude malignancy confidently, and FNA or biopsy is needed to determine the nature of the nodule."
Can color Doppler sonography aid in the prediction of malignancy of thyroid nodules?Frates, M et al
Department of radiology, Harvard Medical School, Brigham and Women’s Hospital, Boston, MA
J Ultrasound Med 2003 February; 22:127-131
By Ultrasound Review
March 24, 2003
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