Brain amyloid imaging--FDA approval of florbetapir F18 injection.

n engl j med 367;10 nejm.org september 6, 2012 885 of disorders, some of which can be treated (e.g., severe depression or effects of medications) but others of which may signal the development of incurable dementias, such as Alzheimer’s disease. For these reasons, the development and improvement of diagnostic procedures — and neuroimaging procedures, in particular — that aid in characterizing cognitive impairment is a health care priority. Improved diagnostic evaluation of patients with cognitive impairment may also enhance the development of therapies, since reliable diagnoses are critical to the success of clinical trials. Recently, the Food and Drug Administration (FDA) approved a new radiopharmaceutical agent to assist clinicians in detecting causes of cognitive impairment other than Alzheimer’s disease. Florbetapir F18 injection (Amyvid, Eli Lilly) is indicated for positronemission tomographic (PET) imaging of the brain in cognitively impaired adults undergoing evaluation for Alzheimer’s disease and other causes of cognitive decline.2 Florbetapir binds to amyloid aggregates in the brain, and the florbetapir PET image is used to estimate the density of β-amyloid neuritic plaque. As a component of a comprehensive diagnostic evaluation, the finding of a “negative” florbetapir scan (as qualified below) should intensify efforts to find a non–Alzheimer’s disease cause of cognitive decline. Florbetapir brain imaging is a new type of nuclear medicine imaging, and the interpretation of the image requires special training. The unique features of the imaging information also require careful consideration when the scan results are integrated into a diagnostic evaluation. Although the pathophysiological consequences of accumulation of β-amyloid in the brain are uncertain, neuropathological identification of amyloid plaques, typically at autopsy, has long been recognized as essential to confirming the diagnosis of Alzheimer’s disease. Because β-amyloid plaques in the brain have been described as a “hallmark” of Alzheimer’s disease, some clinicians may regard the florbetapir scan as a new test for the disease.3 But the drug was developed exclusively to estimate the density of β-amyloid neuritic plaque in the brain, and these plaques have Brain Amyloid Imaging — FDA Approval of Florbetapir F18 Injection