The role of ultrasound elastography in preoperative localization of parathyroid lesions: a new assisting method to preoperative parathyroid ultrasonography

Abstract

After the definition of minimally invasive procedures, preoperative localization of parathyroid lesions is now crucial. False-positive results up to 30% were reported by B-mode grayscale ultrasonography (US) in localization of parathyroid lesions. Parathyroid adenomas are relatively stiff lesions. Ultrasound elastography (USE) can accurately evaluate tissue stiffness and might detect the stiff parathyroid lesions. The aim of this study is to demonstrate whether USE can detect the level of the stiffness and help the preoperative localization of parathyroid lesions during parathyroid ultrasonography examination. The patients who were candidates for parathyroidectomy were prospectively enrolled to this study and were evaluated by USE. Seventy-two patients with 93 parathyroid lesions underwent parathyroidectomy. Sixty-three patients including three multiple endocrine neoplasia type-1 patients had primary hyperparathyroidism, three patients with chronic renal disease (CRD) had tertiary hyperparathyroidism, three patients with CRD and two renal transplanted patients had persistent secondary hyperparathyroidism. One patient was excluded. While all parathyroid adenomas exhibited high levels of stiffness (score 3 and 4), 17 (63%) out of 27 parathyroid hyperplasia lesions were shown to have significantly higher elasticity. The evaluation of median strain ratios of parathyroid lesions revealed that parathyroid adenomas demonstrated significantly higher levels of stiffness than hyperplasias (P ≤ 0·001). This is the first study that evaluates the ultrasound elastographic features of parathyroid lesions. Parathyroid adenomas were shown to appear as stiff lesions, and half of the hyperplasias showed high elasticity. Parathyroid elastography is a novel technique to evaluate parathyroid lesions and might be a guide for surgeons to determine the type of operation to apply.