Clinical Value Of High-Frequency Ultrasound In The Diagnosis Of Papillary Thyroid Microcarcinoma

ObjectiveTo assess the specific ultrasonic characteristics of Papillary Thyroid Microcarcinoma (PTMC) and to investigate the clinical value of high-frequent ultrasound in the diagnosis of PTMC.Materials and MethodsClinical data:196 patients with 209 thyroid nodules from Jan 2008 to May 2010 were retrospectively reviewed. All masses were less than 1.0 centimeters in their greatest diameter and confirmed by operation and pathology.Equipment and method:The equipment in the study was Philips HDI5000 which used linear array high frequency probe and the frequency was 7～12MHz. All tumors were examined by 2D ultrasound and color Doppler flow imaging. Bilateral neck scanning was applied to detect abnormal lymph nodes. Statistics index (Sensitivity, specificity, accuracy and so on) were obtained and each nodule was scored based on its ultrasonic characteristics.Statistical analysis:Statistical data-processing applied package SPSS 13.0. A X2-test and a Fisher exact test were applied for different ultrasonic characteristics between-group statistical analysis; All the data were described as means±standard and independent-samples T test was used to compare the scores of the two sets of samples. p<0.05 for the differences were statistically significant.Results196 patients with 209 thyroid nodules confirmed by operation and pathology included 68 cases with PTMC (74 nodules) and 128 cases with benign lesions (135 nodules). The benign lesions included 107 nodular goiter,13 adenoma and 15 focal Hashimoto's thyroiditis and focal subacute thyroiditis.Statistically significant (P<0.05) findings of PTMC were spiculate margin (sensitivity,62.2%; specificity,91.9%; accuracy,81.3%), irregular shape (sensitivity,60.8%; specificity,93.3%; accuracy,81.8%), marked hypoechogenicity (sensitivity,47.3%; specificity,92.6%; accuracy,76.6%),A/T (anteroposterior/transverse diameter ratio)≥1 (sensitivity,66.2%; specificity,93.3%; accuracy,83.7%), microcalcifications (sensitivity,62.2%; specificity,97.8%; accuracy, 85.2%), enlarged lymph nodes on the neck (sensitivity,18.9%; specificity,95.6%; accuracy,68.4%) and abundant blood flow signals inside the lesions (sensitivity, 27.0%; specificity,94.8%; accuracy,70.8%). If all the ultrasonic characteristics above were taken into account, ultrasonography in diagnosing PTMC had a sensitivity of 91.9%, a specificity of 94.1% and a diagnostic accuracy of 93.3%.There were differences in ultrasonic scores between the benign and malignant nodules. Malignant nodules got higher scores than benign ones. If the critical point of total scores was 3.5, the accuracy was 94.3%.ConclusionHigh-frequent ultrasound is valuable in the diagnosis of PTMC. Margin, shape, echogenicity, A/T, presence of calcification, enlarged lymph nodes on the neck and blood flow signals inside the lesions are helpful indicators for the discrimination of PTMC from benign nodules.Presence of microcalcification, taller than wide, irregular shape, spiculate margin and marked hypoechogenicity which have relatively high diagnostic accuracies are important indicators in the discrimination of PTMC from benign nodules. For enlarged lymph nodes on the neck and the abundant blood flow signals inside the lesions, their sensitivities and accuracies are low but specificities are high, which can be used as efficacious reference indication. Taking all the ultrasonic characteristics into account can improve the diagnostic accuracy.Ultrasonic semi-quantitative scores showed some value in improving the accuracy of diagnosis.