ARFI ELASTOGRAPHY IN THE DIAGNOSIS OF THYROID NODULES

Abstract

Objective: To describe the sonography characteritics of the thyroid nodules using Acoutic Radiation Force Impulse Imaging (ARFI), and to evaluate the role of ARFI technique combination with 2D Ultrasound in diagnosing thyroid nodules. Methods: 2D Ultrasound and ARFI Elatography were caried out in 63 patients who have thyroid nodules. Images of 2D Ultrasound were classified according to Russ G. (French TIRADS). ARFI Elastography was performed by 2 techniques: “ Virtual Touch tissue imaging” in order to image of strain distribution and “Virtual Touch tissue quantification Imaging” to measure the shear wave velocity (SWV) in the tissue. Strain distribution was classified according to Xu’s VTI grading method. SWV was measured in the solid portions or suspicious regions of a nodule, avoiding cystic portions or calcifications. According to the results of pathology, we determine and compare the value between 2D Ultrasound plus ARFI elastography and 2D Ultrasound alone. Results: 63 patients with thyroid nodules: 14 malignant nodules and 49 benign nodules. The mean SWV of benign nodules were 1.78±1.22 m/s, the mean SWV of malignant nodules were 7.09±2.87 m/s. The best cut-off point for SWV was 2.4 m/s. For VTI, grade IV was the best cut-off value in differentiation of benign and malignant thyroid nodules. 2D Ultrasound plus VTI and 2D Ultrasound plus VTQ: Se 100% and 100%, Sp 87.8% and 85.7%, PPV 70% and 66.7%, NPV 100% and 100%, Acc 90.5 % and 88.9% (K=0.761 and K=0.727). Conclusions: In addition to the morphologic characteristics of thyroid nodules, ARFI provides information about lesion’s tissue elasticity, which can be useful tool in diferential diagnosis of thyroid nodules. Key words: Acoustic Radiation Force Impulse Imaging (ARFI), thyroid nodules