Efficacy of Ultrasound Shear Wave Elastography in the Diagnosis of Salivary Gland Tumors

Abstract

Purpose: Diagnostic accuracy of fine-needle aspiration cytology (FNAC) to discriminate between the target condition and health in the evaluation of salivary gland tumors is not perfected yet and thus, false-negative results are possible. The purpose of the present study was to measure and compare the diagnostic accuracy of FNAC performed with conventional B-mode ultrasound and ultrasound with shear wave elastography (SWE) FNAC navigation.

Methods: The investigators implemented a single-blind randomized study (sealed envelope method). The study population was composed of all patients presenting for evaluation and management of suspected benign or malignant tumors of the major salivary glands between July 2013 and December 2020. The involvement of SWE navigation was the primary predictor variable affecting FNA targeting. The method involved analysis of redistribution of SWE values within the affected gland expressed in kilopascals (kPa) and the four-point ES1 (soft tissue) to ES4 (stiff) scoring. The primary outcome variable was the success in obtaining diagnostic tissue resulting in a histologically confirmed FNAC diagnosis and coded as yes/no. Age and sex of the patients and topographical locations of lesions were covariates. Descriptive and bivariate statistics were computed and the P value was set at .05.

Results: The sample included 132 subjects (male/female 59/73; mean age 54 ± 11 years; 144 tumors). SWE + Group (n = 66) consisted of patients presurgically diagnosed with salivary tumors SWE-guided FNAC and SWE- Group (n = 66) was diagnosed with tumors by conventional ultrasound-(B-mode)-guided FNAC. The SWE-guided FNAC statistically significantly reduced the incidence of false-negative results (n = 0; P = .001) and nondiagnostic cases (n = 3 SWE FNAC vs n = 7 B-mode US FNAC; P = .04). For SWE + Group, the FNAC diagnosis was confirmed by postsurgical histology in 95.5% with 91.0% sensitivity (confidence interval [CI] 0.62 to 0.97) and 84.4% specificity (CI 0.58 to 0.96). For SWE- Group, 81.8% confirmation was obtained (P = .05) with 82.3% sensitivity (CI 0.54 to 0.90) and 74.0% specificity.

Conclusion: SWE can increase success in obtaining diagnostic tissue when used for FNAC navigation purposes. We suggest combining both SWE and standard B-mode ultrasonography methods when the FNAC procedure is performed.