Application Of 18MHz High Frequency Linear Array Probes In The Diagnosis Of Thyroid Nodules

OBJECTIVE:To evaluate the utility of 18MHz high-frequency linear array ultrasound probe in the diagnosis of thyroid nodules, and compare it with conventional high-frequency ultrasound probe.METHODS:The study prospectively evaluated 103 nodules in 85 patients who were referred for operation from December 2015 to Match 2016. The patients underwent two kinds of probes(18MHz and conventional high-frequency probes) before operation. Compared the different sonographic appearances of malignant nodules by using two kinds of probes and assessed their diagnostic accuracy and predictive values as the gold standard.RESULTS:The acoustic images of malignant nodules in the conventional high-frequency probe were solid, ill-defined border, no halo, microcalcifications, while in the 18MHz probe their performance can be small cystic degeneration, spiculated margin, irregular halo sign, fibrosis, coarse calcifications or echogenic foci with comet-tail artifact, the diagnostic accuracy of different malignancy signs by using 18MHz and conventional high-frequency probes were different, solid(67.0% vs 83.4%), spiculated margin (67.0% vs 47.6%), ill-defined border (54.3% vs 69.9%), no halo (63.1% vs 72.8%), irregular halo (48.5% vs 38.8%), microcalcifications (68.0% vs 57.1%).Statistically significant differences in the boundary, halo, ratio of length/width were observed between the PTMC and non-PTMC group (P<.05) by using 18MHz probe. However, statistically significant differences in the ratio of length/width, cystic changes, calcifications when using conventional high-frequency probe.CONCLUSIONS:1.The sonographic characteristics were different between 18MHz and conventional high-frequency transducers. The traditional diagnostic criteria for thyroid nodules would be challenged with the application of 18MHz probes. It provided richer and more accurate diagnostic information for identification of benign and malignant thyroid nodules.2.The combination of various frequencies of probes can improve the diagnostic accuracy of thyroid nodules.OBJECTIVE:To evaluate the utility of 18MHz high-frequency linear array ultrasound probe in the diagnosis of t thyroid anterior capsular invasion, and compare it with conventional high-frequency ultrasound probe.METHODS:The study prospectively evaluated 73 nodules in 68 patients who were referred for operation from December 2015 to Match 2016. The patients underwent two kinds of probes(18MHz and conventional high-frequency probes) before operation. The diagnostic accuracy and predictive values of extrathyroid extension with the two kinds of probes were assessed using histopathological examination as the gold standard, and analyzed several predictive factors for extrathyroidal extension based on preoperative sonography.RESULTS:When thyroid capsular invasion on sonography was defined as the capsular abutment,which means lack of intervening tissue between the thyroid cancer and the thyroid capsule, regardless of the disruption of the perithyroidal echogenic line,18MHz probes has higher diagnostic accuracy for thyroid capsular invasion. It was higher than conventional high-frequency ultrasound probe in terms of specificity (90.7% vs 69.8%), positive predictive value (87.1% vs 68.3%) and accuracy (90.4% vs 79.5%). When thyroid capsular invasion on sonography was defined as disruption of the perithyroidal echogenic line, conventional high-frequency ultrasound probe was lower than 18MHz probe in terms of sensitivity(53.3% vs 70.0%), positive predictive value (74.5% vs 82.0%),negative predictive value (88.9% vs 91.3%) and accuracy (78.1% vs 84.9%). Some ultrasonography characteristics such as thyroid nodule calcification and central lymph node metastasis are useful predictive factors for thyroid anterior capsular invasion.CONCLUSIONS:1. When extrathyroidal extension on sonography was defined as the capsular abutment,which means lack of intervening tissue between the thyroid cancer and the thyroid capsule, regardless of the disruption of the perithyroidal echogenic line,18 MHZ high frequency probe is superior to the conventional high frequency probe in the diagnosis of thyroid anterior capsular invasion.2. Thyroid carcinoma calcification and central lymph node metastasis are useful predictive factors for thyroid capsular invasion.