Elastography for Thyroid Nodules: The Comparison of Diagnostic Performance on Transverse and Longitudinal Planes

ABSTRACT

PURPOSE: To evaluate the diagnositc performance of elastography for thyroid nodules on the transverse and longitudinal planes. MATERIALS AND METHODS: Gray scale ultrasonography (US), elastography on transverse and longitudinal planes, and fine needle aspiration biopsy for 78 thyroid nodules (malignant 34 cases, benign 44 cases) were performed. According to the Asteria criteria of elastography, scores 1 and 2 were classfied as probably benign and scores 3 and 4 were classifeid as suspicious. Strain ratios on transverse and longitudinal planes were measured. Sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and Az value (under the receiver operating characteristics curve) of elastography on transverse and longitudinal planes were calculated and compared. RESULTS: Scores 3 and 4 were more frequently seen in malignant nodules on the longitudinal plane (p value = 0.007), but not significantly seen on the transverse plane (p value = 0.160). Sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and the Az value of elastography on the longitudinal plane were higher than those on the transverse plane, although Az values on the transverse and longtudinal planes were not statistically significant. CONCLUSION: Diagnostic performance of thyroid elastography, especially sensitivity, were higher on the longitudinal plane than the transverse plane.