Comparison of elastographic strain index and thyroid fine-needle aspiration cytology in 631 thyroid nodules.
BACKGROUND
Ultrasound (US) elastography (USE) was recently been reported as a sensitive, noninvasive tool for identifying thyroid cancer. However, the accuracy of this technique is hampered by the intra- and interoperator variability, some US features of the nodule, and the coexistence of autoimmune thyroid disease (ATD).


OBJECTIVE
The purpose of this article was to assess the accuracy of USE findings in the differential diagnosis of thyroid nodules compared with other US features to evaluate its feasibility in the presence of ATDs and identify the strain index (SI) cutoff with the highest diagnostic performance.


METHODS
We evaluated 528 consecutive patients for a total of 661 thyroid nodules. All nodules underwent fine-needle aspiration cytology (FNAC) and USE evaluation. The SI was calculated as a ratio of the nodule strain divided by the strain of the softest part of the surrounding normal tissue.


RESULTS
The median SI value was significantly higher in THY4 and THY5 than in THY2 nodules in ATD-positive, ATD-negative, and ATD-unknown patients. The cutoff of SI for malignancy was estimated to be 2.905 by receiver operating characteristic curve analysis in a screening set (379 FNAC results), and then tested in a replication set (252 FNAC results). In all cases, a SI value of ≥ 2.905 conferred to the nodule a significantly greater probability of being malignant. This SI cutoff had the greatest area under the curve, sensitivity, and negative predictive value, compared with the conventional US features of malignancy.


CONCLUSIONS
The elastographic SI has a high sensitivity, specificity, and negative predictive value for the diagnosis of thyroid malignancy both in the presence and in the absence of ATD. If our data on USE are also confirmed in THY3 nodules, FNAC could be avoided in a number of thyroid nodules with certain features.
MD, PhD, Unit of Internal Medicine and Endocrinology, Fondazione Salvatore Maugeri Istituto di Ricovero e Cura a Carattere Scientifico, via S. Maugeri 10, 27100 Pavia, Italy. luca.chiovato@fsm.it.
Flavia
F
Magri
Spyridon
S
Chytiris
Valentina
V
Capelli
Margherita
M
Gaiti
Francesca
F
Zerbini
Roberto
R
Carrara
Alberto
A
Malovini
Mario
M
Rotondi
Riccardo
R
Bellazzi
Luca
L
Chiovato
D018263:Adenocarcinoma, Follicular / Q000150:complications / Q000000981:diagnostic imaging / Q000473:pathology; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003937:Diagnosis, Differential; D054459:Elasticity Imaging Techniques; D061765:Endoscopic Ultrasound-Guided Fine Needle Aspiration; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011230:Precancerous Conditions / Q000150:complications / Q000000981:diagnostic imaging / Q000473:pathology; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013961:Thyroid Gland / Q000000981:diagnostic imaging* / Q000473:pathology*; D013964:Thyroid Neoplasms / Q000150:complications / Q000000981:diagnostic imaging* / Q000473:pathology*; D016606:Thyroid Nodule / Q000145:classification / Q000150:complications / Q000000981:diagnostic imaging* / Q000473:pathology*; D013967:Thyroiditis, Autoimmune / Q000150:complications