Virtual evaluation of selected cervical lymph nodes with three-dimensional ultrasound in thyroid cancer patients after thyroidectomy

Background: We evaluated the usefulness of three-dimensional (3D) ultrasound of cervical lymph nodes (LN), when two-dimensional (2D) ultrasound evaluation is not sufficient to clearly evaluate lymph node characteristics, in thyroid cancer patients being followed after thyroidectomy. Methods: Two readers retrospectively analyzed 2D and 3D images of 147 LNs; LNs were categorized as normal, reactive, suspicious, or indeterminate, and confidence level was rated. Results were compared to cytological/clinical data. Inter-reader agreement was calculated. Results: Addition of 3D ultrasound significantly increased specificity (0.787 with 2D ultrasound vs 0.905 with 2D + 3D ultrasound for reader 1, P =.009; 0.701 with 2D ultrasound vs 0.898 with 2D + 3D ultrasound for reader 2, P =.01). Addition of 3D ultrasound significantly increased confidence level of readers (P <.001). Inter-reader agreement in LN categorization was almost perfect with 2D + 3D ultrasound. Conclusion: 3D ultrasound of cervical LNs enables better demonstration of imaging features that are important in differentiating benign and malignant LNs. These improvements can potentially obviate the need for FNA in post thyroidectomy cancer patients.