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Alzheimers Dementia |
Neurologic PET There are a number of positron emitting radiotracers available for brain imaging. However, the only radiotracer approved for routine reimbursement is FDG. Focal or regional FDG uptake reflects metabolic activity of that intracranial region or focus. Remember that FDG of the brain grey matter is normally very intense and that we are often, but not always, looking for an abnormal decrease in regional FDG activity (such as with interictal seizures or Alzheimer’s evaluation). There are currently two CMS (Medicare) approved indications for neurologic PET. These are generally also approved by private insurers: Epilepsy: Ictal focus localization in patients who are refractory to medication and are being considered for surgical resection. These patients are typically imaged in between seizures. Alzheimer Dementia: Those patients who have been evaluated by a dementia specialist and in whom the diagnosis of Alzheimer Dementia is suspected but still in doubt. Also, those patients who are involved in specifically approved national trials for Alzheimer Dementia. In addition to the above two indications, some private insurers will approve neurologic PET imaging for other indications, most commonly oncologic: Differentiating recurrent brain tumor from benign radiation necrosis. In patients that have received brain radiation, both benign necrosis and tumor recurrence can enhance on follow-up CT or MRI. PET can help distinguish the two by demonstrating increased activity in recurrent tumor and none in radiation necrosis. Differentiating benign from malignant processes, such as infarct or in an AIDS patient, CNS toxoplasmosis from CNS lymphoma (the latter generally having intense FDG uptake). Other neurologic PET studies are possible with other radiotracers such as cerebral perfusion and oxygen metabolism or more specialized tracers such as to evaluate dopamine receptors in Parkinson’s Disease. However, these are at present typically performed in a research setting. To schedule a clinical brain PET or to inquire into the possibility of coverage, please call 773-702-0336, (or 2-0336 from within the University of Chicago). |
