Ultrasonography and Ultrasound-Guided Intervention of Salivary Glands

Abstract

An accurate diagnoses of salivary gland masse is clinically critical for optimal patients' management. A patient with sialadenitis, benign neoplasm or lymphoid hyperplasia may be treated conservatively. Patients with lymphoma may undergo chemotherapy or radiation therapy after systemic staging, while those with primary malignancy may be treated by surgery. Ultrasonography (US) has become an optimal diagnostic tool due to its non-invasiveness, non-irradiation, multi-planar capability and high portability. US-guided fine needle aspiration (USFNA) and US-guided core needle biopsy (USCNB) have also been used to increase the accuracy in diagnosing salivary gland masses. On sonograms, significant difference can be found between the benign and malignant lesions of parotid gland with respect to the shape. The benign neoplasms and lymphoid hyperplasia are more likely to have homogeneous texture, well-defined margin and round or oval shape; while the malignancies and inflammatory lesions tend to be heterogeneous with indistinct margin and irregular shape. USFNA is a well-accepted and widely used technique for the preliminary diagnosis of salivary gland masses. It is safe, fast, and well-tolerated. In the literature, on average, it has a high specificity (98%) but lower sensitivity (80%) in differentiating benign from malignant salivary gland masses. According to our reports, USFNA has a sensitivity of 71%, a specificity of 98%, and an accuracy of 94% in differentiating benign from malignant parotid masses. The corresponding figures for the USCNB are 98%, 100% and 98%, respectively. USCNB has positive and negative predictive values of 100% and 96%, respectively, in diagnosing malignancies. Thus, a positive diagnosis by FNAC is reliable, but the false-negative rate associated with FNAC may be unacceptable. Accurate diagnoses and sub-typing of lymphoma cannot be reliably made on the basis of cytology. A meta-analysis report on five studies with 277 cases published between 2002 and 2009 showed that the sensitivity of USCNB is 0.92 (95% CI, 0.77-0.98) and the specificity is 1.00 (95% CI, 0.76-1.00). It is concluded that USCNB has a high accuracy and a low (1.2%) inadequacy rate for diagnosing salivary gland masses. In this presentation, the techniques to avoid complications of USCNB will also be discussed.