Female, 77 years old, with history of parotid cancer status post induction chemotherapy. Please note that comparison will be made largely with reference to the prior CTA dated 3/18/2015 as the field of view of the prior MRI is not adequate for accurate comparison.An extensive infiltrative tumor is redemonstrated, centered on and involving nearly the entirety of the right parotid and masticator spaces. Tumor infiltrates the hemimandible from the level of the condyle as far anteriorly as the mentum. Tumor extends laterally almost to the skin surface, and medially to the level of the parapharyngeal and pharyngeal spaces. Superiorly, tumor appears to infiltrate into the temporalis muscle.Tumor infiltrates into the pterygopalatine fossa, the sphenoid sinuses, the clivus and the sella. Meckel's cave and the right cavernous sinus are nearly completely infiltrated as well. The right ICA flow void is moderately narrowed as a result. Tumor encroaches upon the right prepontine cistern and tracks along the petrous bone to very nearly enter the right IAC.Tumor erodes through the bony floor of the right middle cranial fossa and invades and thickens the dura in this area. Tumor tracks along the anterior clinoid process and may slightly encroach upon the right orbital apex. The right mastoid air cells demonstrate fluid signal intensity likely indicating outflow obstruction.On comparison to the prior exam, it does appear that the lesion is overall larger and more widely infiltrative throughout. As a very rough estimate, the maximal dimension of this lesion at the level of the masticator space is at least 77 mm, and on the prior CT the same dimension is probably no more than 60 mm.Intracranially, despite the extensive tumor erosion into the right middle cranial fossa and infiltration/thickening of the regional dura, no definite evidence of parenchymal edema or pathologic parenchymal enhancement is seen to suggest frank brain invasion.No restricted diffusion is seen within the brain. A few scattered small foci of nonspecific T2 hyperintensity are evident within the cerebral hemispheres. No significant mass effect is detected. No evidence of significant intracranial hemorrhage or any abnormal extra-axial collection is seen. The ventricles are normal in size and morphology. Loss of the T2 flow void of the right transverse and sigmoid sinus is seen, likely indicating slow flow as the sinus does appear to enhance normally on postcontrast images.
A diffusely infiltrative tumor is redemonstrated centered upon the right parotid and masticator spaces. As on the prior exam, this lesion extensively invades the regional structures and spaces including the pterygopalatine fossa, sphenoid bone, clivus and sella, Meckel's cave and cavernous sinus, extending even into the prepontine cistern. Tumor also extensively invades through the floor of the right middle cranial fossa with infiltration and thickening of the regional dura. Accurate comparison is complicated by lack of prior MRI with an adequate field of view, but despite this, it does appear that the lesion has become at least moderately more extensive than previously.Although there is extensive intracranial invasion as above, no definite evidence of brain parenchymal involvement is seen.