Brain PET in the diagnosis of Alzheimer's disease

Abstract

Objectives: The aim of this article was to review the current role of brain PET in the diagnosis of Alzheimer dementia. The characteristic patterns of glucose metabolism on brain FDG-PET can help in differentiating Alzheimer's disease from other causes of dementia such as frontotemporal dementia and dementia of Lewy body. Amyloid brain PET may exclude significant amyloid deposition and thus Alzheimer's disease in appropriate clinical setting.

Conclusions: FDG-PET and amyloid PET imaging are valuable in the assessment of patients with Alzheimer's disease.

FIGURE 1

Mild cognitive impairment: ¹⁸F-FDG brain PET/CT study of a 61-year-old woman who presented with history of progressive confusion, disorientation, and urinary incontinence. She has a history of surgery for a benign cerebellar tumor at 5 years of age. The left and right lateral (A) and left and right medial (B) 3-dimensional stereotactic surface projection images of FDG hypometabolism demonstrate mild glucose hypometabolism in the parietal and posterior cingulate cortices (compared with a normal brain database, Mim software 6.2, Cleveland, OH. Light blue, −1 SD; dark blue, −2 SDs; purple, −3 SDs), features consistent with MCI. Postsurgical changes appreciated in the cerebellum.

FIGURE 2

Alzheimer’s disease: ¹⁸F-FDG brain PET/CT study of a 50-year-old woman with progressive amnesia and dysgraphia for 18 months. The left and right lateral (A) and left and right medial (B) 3-dimensional stereotactic surface projection images of FDG hypometabolism demonstrate glucose hypometabolism involving the posterior cingulate gyrus and bilateral parietal cortices extending to the temporal region (compared with a normal brain database, Mim software 6.2. Light blue, −1 SD; dark blue, −2 SDs; purple, −3 SDs), features consistent with early AD.

FIGURE 3

Alzheimer’s disease: ¹⁸F-FDG brain PET/CT study of a 81-year-old man with cognitive decline during the past few months. The left and right lateral (A) and left and right medial (B) 3-dimensional stereotactic surface projection images of FDG hypometabolism demonstrate glucose hypometabolism involving the bilateral frontal, temporal, and parietal cortices (compared with a normal brain database, Mim software 6.2. Light blue, −1 SD; dark blue, −2 SDs; purple, −3SDs), with sparing of the sensorimotor and occipital cortices, features consistent with AD.

FIGURE 4

Lewy body dementia: ¹⁸F-FDG brain PET/CT study of a 43-year-old woman with memory loss and visuospatial dysfunction. The left and right lateral (A) and left and right medial (B) 3-dimensional stereotactic surface projection images of FDG hypometabolism demonstrate glucose hypometabolism involving the bilateral occipital and parietal cortices, extending to the temporal cortex (compared with a normal brain database, Mim software 6.2. Blue, −2 SDs; purple, −3 SDs), features suggestive of Lewy body dementia.

FIGURE 5

Frontotemporal dementia: ¹⁸F-FDG brain PET/CT study of a 72-year-old woman with anomia, progressive memory impairment, cognitive decline, and gradual paucity of speech. The left and right lateral (A) and left and right medial (B) 3-dimensional stereotactic surface projection images of FDG hypometabolism demonstrate glucose hypometabolism involving the bilateral frontal and temporal cortices (compared with a normal brain database, Mim software 6.2. Blue, −2 SDs; purple, −3 SDs), compatible with a diagnosis of frontotemporal dementia.

FIGURE 6

Negative amyloid brain PET result: ¹⁸F-florbetapir brain PET/CT study of a 75-year-old man with history of cerebral amyloid angiopathy with gradual decline in cognitive function over 3 years. Axial PET images demonstrate normal grey-white differentiation in the cerebellum (A) and in the cerebrum (B and C) consistent with sparce amyloid neuritic plaques density, inconsistent with the neuropathology of AD.

FIGURE 7

Positive amyloid brain PET result: ¹⁸F-florbetapir brain PET/CT study of a 71-year-old woman with history of short-term memory loss for 2 years. The axial PET images of the cerebellum (A) demonstrate the normal grey-white differentiation, but there is loss of grey-white differentiation in occipital and frontal lobes (B and C), suggesitve of moderate-to-severe amyloid neuritic plaques density. This can be observed in cognitively normal individuals as well as those with AD.