Imaging of Salivary Masses

can be broadly divided into focal masses (which may be neoplastic or non-neoplastic), and diffuse salivary diseases, which may be secondary to obstruction of salivary ducts (obstructive sialadenitis) or a wide range of other infective, inflammatory, autoimmune, and other pathologies. The clinical history and examination are important to direct imaging. Pertinent features include prior head and neck disease, smoking history, patient age, speed of onset and growth rate, lesion location, size, and multiplicity, features of obstruction (gustatory swelling, stone passage), malignancy (location, firmness, fixation, facial palsy, enlarged lymph nodes), or infection (fever, rapid enlargement, erythema). Imaging fulfills several roles in the initial work-up, including localization, diagnosis or characterization, staging of malignancies, image-guided biopsy, and therapeutic interventions (aspiration and stone extraction). A handful of pathologies have characteristic diagnostic imaging appearances such as sialoceles, ranulas, lipomas, neurogenic tumours, and AVMs. However, many lesions, including salivary neoplasms cannot be diagnosed definitively by imaging and thus require fine needle or core needle biopsy for confirmation. The choice of imaging for salivary masses depends on many factors, including presumptive diagnosis, available resources, and expertise, although wherever available, ultrasound (US) is the preferred initial technique. US is safe, inexpensive and allows characterization and localization, as well as image-guided biopsy. By allowing preliminary characterisation different types of pathology, for example by separating masses into those with nonaggressive (Figure 1) and aggressive features (Figure 2), US serves as a gatekeeper for further imaging. Magnetic resonance imaging (MRI) has excellent soft tissue resolution and is specifically indicated for deep lobe parotid tumours and known or suspected malignancies, where it is important for assessing deep tumour margins, regional lymph nodes, invasion of adjacent structures, and, importantly, perineural spread. Advanced imaging techniques including diffusion-weighted imaging and perfusion analysis with time intensity curves (TICS) have additional diagnostic value for differentiation of Warthin tumours, pleomorphic adenomas, and some salivary malignancies. SHORT ABSTRACT