Ultrasound B-flow imaging in the evaluation of thermal ablation of thyroid nodules.

The aim of percutaneous thermal ablation is to reduce the volume of benign thyroid nodules. B-flow imaging, a non-Doppler technology for blood flow imaging, provides a real-time visualization of vascularity, and gives accurate information on the vessel lumen in high spatial and temporal resolution. Little is known about the possible application of this new technique on thyroid nodules after thermal treatments. Color power Doppler and contrast-enhanced ultrasound are the methods currently used in this context, but they present some limitations. Conversely, during the thermal procedures, B-flow imaging--suppressing unwanted signals (e.g., noise and tissue) and boosting weak signals (e.g., blood echoes)--permits an accurate spatial analysis of the intranodular flow. B-flow imaging may clearly show a complete ablation during the treatment. Moreover, it can also be useful during the follow-up in highlighting the possible intranodular flow regrowth. In conclusion, B-flow imaging--overcoming the limitations of color power Doppler and contrast-enhanced ultrasound-is useful to evaluate, in real time, the necrotic area of thyroid nodules during and after thermal ablative procedures.