Does elastography reduce the need for thyroid FNAs?

Ultrasound elastography (USE) assesses lesion stiffness by evaluating tissue distortion in response to stress; it is emerging as a potentially useful tool to augment the ultrasound characterisation of thyroid nodules. The aim of this study was to assess the accuracy of USE examination of thyroid nodules compared with pathological outcome, especially to determine whether USE could reliably detect benign nodules and reduce the numbers of ultrasound guided fine needle aspiration cytology (USgFNAC).

Over a three-year period, thyroid nodules were initially characterised by B-mode ultrasound (US) findings. Where USgFNAC was indicated by clinical concern and/or the sonographic appearances, the lesion was then subjected to USE by an experienced operator prior to the USgFNAC.

147 thyroid nodules were examined by USE and USgFNAC in 146 patients.

The elastographic appearance was subjectively categorized at the time of the examination (soft, intermediate or hard) and subsequently compared with the cytological/histological outcome.

A total of 122 nodules were non-neoplastic, 5 nodules were benign neoplasms, 10 nodules had indeterminate cytology and 10 were malignant neoplasms. The sensitivity of USE for malignancy was 90.0%, specificity was 79.6%, PPV was 24.3%, NPV was 99.1% and accuracy was 80.3%.

Thyroid nodules that are soft at USE have a high likelihood of being non-neoplastic and subjective USE assessment of thyroid nodules by an experienced operator can be a useful means of avoiding USgFNAC for benign nodules. In contrast, we suggest that all nodules that are intermediate or hard on USE undergo USgFNAC.