Diagnostic accuracy of elastography in thyroid nodule ultrasound evaluation. A prospective multicenter trial

P. Trimboli; I. Misischi; S. Morgante; F. Graziano; M. Deiana; D. Wolosinska; C. Pascucci; A. Bonifacino; C. Bellotti; S. Valabrega; G. Bizzarri; A. Liverani

Background: Real-time elastography (RTE) was reported to improve the diagnostic accuracy of B-mode ultrasound (US) examination of thyroid nodules but the results on selected series of patients are still controversial.

Aim of the study: To blindly evaluate on a consecutive series of solid thyroid nodules, devoid of confounding factors, the diagnostic accuracy of RTE and to compare it with the traditional B-mode features.

Materials and methods: From September 2010 until June 2011, 323 consecutive solid thyroid nodules underwent fine-needle aspiration biopsy (FNA) at three thyroid referral centers in Rome. B-mode US and RTE examinations (Mylab 70, Esaote, Genoa, Italy) were performed before FNA and images were stored and blindly reviewed by six experienced endocrinologists. A RTE score (from I, soft, to IV, hard) was assigned on the basis of color pattern, according to a previous classification. Twenty-six nodules (8.0%) with non-diagnostic FNA were excluded and 297 cases were enrolled in the study. Patients with indeterminate, suspicious and malignant cytology were operated upon. Nodules with benign cytology had a clinical and US control after six months.

Results: Ninety-five nodules (32%) were malignant and 202 (68%) benign. The PPV for malignancy provided by the presence of at least one conventional US risk factor (marked hypoechogenicity, microcalcifications, spiculated margins and intranodular vascularization) was 98%, and the NPV due to the absence of any US risk factor was 34%, with a 71% diagnostic accuracy. The PPV for malignancy of class III and IV RTE scores, as a whole, was 60% and the NPV was 85%, with a 75% diagnostic accuracy. When evaluated separately, marked hypoechogenicity, microcalcifications, spiculated margins and intranodular vascularization showed a 90%, 75%, 61%, and 65% diagnostic accuracy, respectively.

Conclusions: In unselected solid thyroid nodules, and in absence of confounding sonographic factors, RTE showed a diagnostic accuracy similar to the single traditional US risk factors. The PPV for malignancy provided by the presence of at least one US suspicious finding, however, was superior to that of combined class III and IV RTE scores.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.

Endocrine Abstracts

P1607