Virtual Biopsy and Three Dimensional Ultrasound for Radio Frequency Ablation of Thyroid Nodules
AIMS & OBJECTIVES
Free-hand Ultrasound (US) plays an important role in thyroid diagnostics as a real-time examination, not ionizing and non-invasive, cost effective, ideal also for repetitive followup and able to give information about anatomy (B-Mode modality), hemodynamics (Color, Power Doppler) [1,2] and tissue stiffness, i.e. Elastosonography .
Furthermore, US is the most used imaging technology for guiding fine needle aspiration biopsy  and minimally invasive treatments of the thyroid, for instance Radio Frequency Ablation (RFA), Ethanol injections  or Laser .
A recently published Consensus Statement and Recommendations review article  describes a moving shot technique under local anesthesia as a safe and effective RFA procedure (moving technique necessary especially for the prevention of voice change). Moreover, a continuously monitored US-guided tracing of the electrode tip is mandatory during RFA. Evaluation of the internal vascularity of the nodules is requested. Three orthogonal nodule diameters, in order to calculate the volume of the nodule, have to be measured and evaluated, also after the treatment, and for follow up at 1-2, 6 and at 12 months after RFA procedure, as well as every 6-12 months thereafter, depending on the status of the treated nodules .
The present work is a technological analysis and evaluation of advanced US technologies (Virtual Biopsy, Three-dimensional reconstruction, Elastosonography, Color and/or Power Doppler and low mechanical index Contrast enhanced US – CEUS) that can answer to the practical needs of RFA of thyroid nodules.
The innovative Virtual Biopsy technology allows virtual needle visualization during the above mentioned moving shot technique. To assess the results of the RFA procedure a comparison between pre-post ablation is also performed by three-dimensional real-time US acquisition of the interested area, acquired both with motorized probe as well freehand US probe coupled with Electromagnetically (EM) tracking system.
Furthermore, the procedure was enhanced by a Motion Compensation (MC) technique, using a Motion Control Sensor (MCS), which corrected possible subject’s voluntary, or involuntary movements, for patient’s and sonographer’s increased comfort and easier US scanning.