Shear wave elastography can improve the preoperative diagnosis of parathyroid carcinoma or atypical parathyroid tumor: initial experience

Parathyroid carcinoma (PC) and atypical parathyroid tumor (APT) are rare malignant lesions characterized by high recurrence and metastasis rates, and accurate preoperative diagnosis remains a clinical challenge. The purpose of this study was to explore the diagnostic value of preoperative grayscale ultrasound combined with shear wave elastography (SWE) for such lesions. In this retrospective case-control study, patients with primary hyperparathyroidism and suspicious parathyroid abnormality on ultrasonography were recruited. All the lesions were assessed by SWE before surgery. Sonographic features and SWE performance along with demographic and related clinical parameters between PC/APT and PA groups were analyzed. This study included 21 patients with PC or APT matched to 84 patients with PA who underwent parathyroid surgery. The best subset selection method and multiple logistic regression analysis identified the sonographic features of intra-nodal fibrous bands and the ratio of mean shear wave velocity in tumor (SWVmean)/shear wave velocity in thyroid parenchyma (SWVth) as independent factors for PC/APT prediction (odds ratio [OR] = 38.536, 95% confidence interval [CI] = 1.188–1250.066, P = 0.04; OR = 248.783, 95%CI = 1.314–47100.432, P = 0.04, respectively). On receiver operating characteristic curve analysis, the optimal cutoff value of the SWVmean/SWVth ratio for predicting PC/APT was 1.25, with a sensitivity of 83.33% and specificity of 95.56% (AUC = 0.894; 95% CI, 0.783–0.960; P < 0.0001). Combined use of the SWVmean/SWVth ratio and intra-nodal fibrous bands showed significantly improved performance for the identification of PC/APT (C statistic = 0.976, P = 0.02; sensitivity = 1; specificity = 0.889; positive predictive value = 0.706, negative predictive value = 1). Sonographic features of combined intra-nodal fibrous bands and the SWVmean/SWVth ratio are suitable markers for accurate preoperative prediction of PC or APT. Not applicable.