Thyroid nodules are a common medical problem. With the wide use of various imaging modalities, incidentally detected thyroid nodules are becoming more common. However most of these nodules are benign with only a small proportion of 5-10% being malignant. With the increasing number of nodules detected, evaluation of these thyroid nodules presents a diagnostic challenge since the imaging modality used for evaluation at present i.e. ultrasound (US) alone has a low specificity of approximately 50-70%. In order to improve specificity to confidently diagnose malignancy in the thyroid nodule, a fine needle aspiration (FNA) biopsy is performed. FNA procedure for a single thyroid nodule costs $624, while an US exam of the thyroid gland costs $233 per Seattle area estimated Medicare Reimbursement Rates. If a patient undergoes an US exam and an FNA procedure on the suspicious lesion, the average cost for thyroid nodule evaluation exceeds $800. Since the yearly incidence of thyroid nodules in the USA population is about 232,000 to 282,000, approximately $225 Million is spent every year to diagnose benign nodules. Thus, to diagnose every malignant nodule, more than $12,000 ($225M/18,000 malignant nodules detected) is spent to detect and exclude the benign nodules. In addition, the invasive nature of the procedure tends to take a toll on the patients, both psychologically and emotionally. In recent years, US elastography has been shown to have high specificity of 90 - 98% in various studies in differentiating between benign and malignant nodules. US elastography works on the principle of detecting the stiffness within a tissue by applying compression which can be manual compression or by generation of a remote radiation force by focused ultrasonic beams called as shear waves. Shear Wave Ultrasound (SWUS) elastography is an objective method of US elastography that detects the stiffness within the nodule since the strength of the shear wave generated is known and can be controlled. SWUS elastography has shown promise in being able to noninvasively diagnose papillary carcinoma in previous studies involving preoperative patients. We propose to perform a study to investigate the efficacy of SWUS elastography in diagnosing malignant thyroid nodules and noninvasively decreasing the number of FNAs performed by avoiding FNA in benign nodules. We will enroll patients with thyroid nodules before they undergo FNA biopsy or surgery. We also propose to compare routine US and SWUS elastography and their combined use in differentiating malignant from benign nodules. We hypothesize that SWUS elastography can be used as a noninvasive screening tool, prior to an FNA, to screen out benign and malignant nodules with high level of confidence and reduce the number of biopsies in the future.
Shear wave ultrasound elastography is a new technique of finding the softness or hardness in tissue by applying a "push" generated by the machine. This technique will help in diagnosing malignancy in the thyroid gland without biopsy and avoiding biopsy in noncancerous nodules.
|Brezak, Robert; Hippe, Dan; Thiel, Jeff et al. (2015) Variability in Stiffness Assessment in a Thyroid Nodule Using Shear Wave Imaging. Ultrasound Q 31:243-9|
|Dighe, Manjiri K (2014) Elastography of Thyroid Masses. Ultrasound Clin 9:13-24|