Doppler ultrasound

Abstract

The Doppler shift is a change in frequency that occurs when sound (or light) is emitted from, or bounced off of, a moving object. The role of Doppler ultrasound in thyroid imaging has recently experienced a significant change. The prior belief that power Doppler imaging plays an important role in the prediction of the likelihood of malignancy in a thyroid nodule has undergone a reassessment. Most of the prior guidelines for management of thyroid nodules considered vascularity as a risk factor for malignancy. More recent studies suggest that vascularity does not have a significant predictive value in most thyroid nodules. Most guidelines still recommend documentation of vascularity in all significant thyroid nodules but do not consider vascularity as a factor determining the need for biopsy. An absent flow pattern does not have sufficient predictive value to eliminate the need to biopsy an avascular solid nodule. Doppler imaging is useful in the evaluation of goiter, thyroid nodules, lymph nodes, and parathyroid glands.