Role of Contrast-Enhanced Ultrasound in Diagnosis of Thyroid Nodules in Acoustic Radiation Force Impulse "Gray Zone".

The aim of this study was to evaluate the clinical value of contrast-enhanced ultrasound (CEUS) in the diagnosis of thyroid nodules in the acoustic radiation force impulse (ARFI) "gray zone" (the shear wave velocity is in the range 2.5-3 m/s). ARFI was performed before thyroidectomy in 70 patients with 200 thyroid nodules, and then CEUS was performed in 40 thyroid nodules in the "gray zone." The accuracy of ARFI for the 200 thyroid nodules was 82% (164/200). The accuracy of ARFI for the 40 "gray zone" thyroid nodules was 70% (28/40), whereas the accuracy of CEUS for the "gray zone" thyroid nodules was 90% (36/40). There was a significant difference in accuracy (p < 0.05). CEUS has better accuracy for thyroid nodules in the ARFI "gray zone." CEUS supplemented ARFI in differential diagnosis of benign and malignant thyroid nodules.