Sonoelastographic evaluation of salivary gland lesions with clinicopathological association

Abstract

Sonoelastography is a comparatively new and developing technology in the field of salivary gland imaging. Nevertheless, it has the potential to distinguish between various types of lesions by calculating the degree of strain-related deformation under the externally applied force. With this background, the present study was undertaken to evaluate the role of sonoelastography in characterising salivary gland lesions as benign or malignant. The aim:          To evaluate and characterize salivary Gland lesions on the Gray scale and Colour doppler ultrasonography and sonoelastography and to correlate these findings with the clinico-pathological diagnosis. Methodology: This prospective cross-sectional study was conducted in the Department of Radiodiagnosis, Teerthanker Mahaveer Medical College & Research Centre, Moradabad (U.P.), from Aug 2021 to Nov 2022. All patients referred to the radiology department for imaging with clinical suspicion of having salivary gland lesions were enrolled in the study and evaluated on the SIEMENS ACUSON S3000 machine. Gray scale USG was done first to assess various morphological features of lesions, and then a Doppler assessment was done to determine vascularity within the lesion. Subsequently, real-time strain elastography (eSie touch) was performed to assess the tissue stiffness. The elastogram image of the detected lesions was evaluated using colour coding ranging from blue (soft) through green (intermediate/average hardness) and red (hard). After strain elastography, shear wave elastography of the lesion was also performed using Virtual Touch Quantification (VTQ) and Virtual Touch Imaging Quantification (VTIQ) software. The sonographic findings were correlated with histopathological diagnosis. The acquired data were subjected to statistical analysis using the software SPSS version 20. Sensitivity, specificity, PPV and NPV were calculated for conventional ultrasound techniques alone & in combination with elastography. Results: Out of the 50 salivary gland lesions included in the study, 44 (88 %) were benign, whereas 6 (12 %) were malignant on cytology. The age of the study population ranged from 16 to 75 years, with a mean age of 38.82 years. Pleomorphic adenoma (60 %) was the most frequent lesion, followed by Warthin's tumour (28 %). The Conventional USG showed 66.67 %, sensitivity, 52.27 %, specificity, 16.00 %, PPV, 92.00 % NPV and 54.00 % accuracy in differentiating benign from malignant lesions while USG- Elastography combined showed higher diagnostic performance with 83.33 %, sensitivity, 79.55 %, specificity, 35.71 % PPV, 97.22 % NPV and 80.00 %, accuracy. The specific cut-off scores for the sonoelastography score, eSie touch, VTQ, and VTIQ were also determined to diagnose a lesion as malignant or benign, and the difference was found to be statistically significant. Conclusions: Sonoelastography alone cannot be solely relied upon to distinguish between malignant & benign salivary gland abnormalities. However, it can be combined with conventional USG for better differentiation and characterization of these lesions