MRI and CT

Magnetic resonance imaging (MRI) and computed tomography (CT) are sophisticated techniques, each with independent strengths. However, rarely do these procedures alter the decision to perform surgery. Their relative value is in evaluating the extent of larger tumors, and associated nodal status and in dif ferentiating deep lobe neoplasms from primary parapharyngeal space lesions.2 Although some controversy exists as to which provides the most meaningful data, MRI in most situations appears to have some advantages. For soft tissue definition, resolution is generally superior. Further, some neoplasms have identifying characteristics noted on MRI studies. Warthin's tumors, for example, are well marginated and heterogeneous, whereas pleomorphic adenomas are homogeneous and smoothly marginated. Differences in signal intensity have been noted for low- and high-grade malignancies. If bone and/or skull base definition is needed, CT can be added as an adjunct to MRI. It should be stated that there is no longer a need for radionuclide imaging or sialography in the management of parotid neoplasms.

For the isolated easily palpable parotid mass, preoperative imaging is not a necessity. Imaging studies are beneficial pre-operatively in defining the extent of larger infiltrative tumors. MRI is the initial imaging modality of choice.

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