Characterization of thyroid nodules by 3-D contrast-enhanced ultrasound imaging

High resolution ultrasound imaging proved effective in the detection, analysis, and follow-up of thyroid lesions, even if interpretative pitfalls remain. Differentiation between malignant and benign nodules is a major challenge: malignancy is often correlated to an increase in intranodular vasculature, due to rapid angiogenesis. We developed a three-step methodology to reconstruct intranodular vasculature based on 3-D contrast-enhanced images: i) preprocessing; ii) morphological opening by using a structuring element coherent with the microbubbles appearance: iii) thresholding and 3-D representation. We processed the volumes relative to 8 nodules (4 benign and 4 malignant, confirmed by needle biopsy) and we calculated the percentage of intranodular contrast agent. Results confirm that malignant nodules present a higher internal vasculature (52.3% +/- 15.7%) than benign (14.3% +/- 5.3%). Also, two experts reported the reconstructed 3-D volumes and scored the nodules characteristics, obtaining a good agreement with bioptic results. We believe this methodology could be useful to improve nodules differentiation in thyroid ultrasound exams.