Positron Emission Tomography Scans Obtained for the Evaluation of Cognitive Dysfunction

Abstract

The degree of intactness of human cognitive functioning for a given individual spans a wide spectrum, ranging from normal to severely demented. The differential diagnosis for the causes of impairment along that spectrum is also wide, and often difficult to distinguish clinically, which has led to an increasing role for neuroimaging tools in that evaluation. The most frequent causes of dementia are neurodegenerative disorders, Alzheimer's disease being the most prevalent among them, and they produce significant alterations in brain metabolism with devastating neuropathologic, economic, social and clinical consequences. These alterations are detectable through positron emission tomography (PET), even in their earliest stages. The most commonly performed PET studies of the brain are carried out with [18F]fluorodeoxyglucose (FDG) as the imaged radiopharmaceutical. Such scans have demonstrated diagnostic and prognostic utility in evaluating patients with cognitive impairment, and in distinguishing among primary neurodegenerative disorders and other etiologies for cognitive decline. In addition to focusing upon the effects on cerebral metabolism examined with FDG PET, some other changes occurring in the brains of cognitively impaired patients assessable with other radiotracers will be considered. As preventive and disease-modifying treatments are developed, early detection of accurately diagnosed disease processes facilitated by the use of PET has the potential to substantially impact upon the enormous human toll exacted by these diseases.

Visual-Statistical Interpretation of 18F-FDG-PET Images for Characteristic Alzheimer Patterns in a Multicenter Study: Inter-Rater Concordance and Relationship to Automated Quantitative Evaluation

“…The AD pattern in 18 F-FDG-PET is usually seen in the early stage of AD and is expected to predict the onset of AD. 1,12 Because most of the subjects who are clinically diagnosed as having AD may have had an established AD pattern in 18 F-FDG-PET, it is reasonable for these results that AD showed the highest concordance.…”

The new FDG brain revolution: the neurovascular unit and the default network

“…Beside, the relationship between brain regions showing changes in neural activity and the clinical status of the patients during scanning can be investigated to reveal the possible circuits involved in the genesis of the cardinal symptoms of brain disorders, to drive drug development and to follow the effects of therapies on cerebral regions with abnormal metabolism. In this respect, as previously highlighted [36], as preventive and disease-modifying treatments are developed, early detection of accurately diagnosed altered processes facilitated by the use of FDG PET has the potential to substantially impact on the enormous human toll exacted by these diseases.…”

Effectiveness and Safety of 18F-FDG PET in the Evaluation of Dementia: A Review of the Recent Literature

“…The diagnostic accuracy of 18 F-FDG PET is high in patients with mild disease, for whom the clinical diagnosis and differential diagnosis are especially challenging. The identification and differential diagnosis of AD is especially challenging in its early stages, partly because of the difficulty in distinguishing it from the mild decline in memory than can occur with normal aging and from cognitive manifestations of other neuropsychiatric conditions, such as depression, as well as other causes of dementia (89).…”