Diagnostic Insights into Salivary Gland Lesions: A Comparative Evaluation of Shear Wave Elastography and MRI ADC Mapping

Purpose: To assess and compare the diagnostic accuracy of ultrasound (USG) shear wave elastography (SWE) and magnetic resonance imaging (MRI) apparent diffusion coefficient (ADC) values in the evaluation of salivary gland lesions. Methods: This prospective study was conducted with Institutional Review Board approval and written informed consent from all participants. A total of 23 patients with salivary gland lesions underwent SWE followed by a limited-sequence MRI to obtain ADC values. SWE measurements were recorded at the lesion site, and corresponding ADC values were calculated from diffusion weighted sequences. Results: Malignant lesions demonstrated lower SWE values than benign lesions, possibly due to cystic and necrotic components within the malignant tumours. A SWE cut-off value >25.9 kPa yielded poor diagnostic performance, with a sensitivity of 25% and specificity of 52.6% (P = 0.39). Similarly, ADC values were lower in malignant lesions, with a cut-off of ≤1.14 × 10⁻³ mm²/s achieving a sensitivity of 75% and specificity of 51.8% (P = 0.41). Notably, a statistically significant variation in SWE values was observed among different ultrasound machines used. Conclusion: SWE alone demonstrated limited diagnostic utility in distinguishing benign from malignant salivary gland lesions. While ADC values showed relatively better diagnostic performance, neither modality reached statistical significance in this small cohort. Nevertheless, both tools may serve as complementary imaging techniques in the diagnostic workup of salivary gland lesions.