Clinical Use and Utility of Amyloid Imaging

Abstract

Currently, 3 amyloid PET tracers are approved and commercially available for clinical use. They allow for the accurate in vivo detection of amyloid plaques, one hallmark of Alzheimer disease. Here, we review the current knowledge on the clinical use and utility of amyloid imaging. Appropriate use criteria for the clinical application of amyloid imaging are established, and most currently available data point to their validity. Visual amyloid image analysis is highly standardized. Disclosure of amyloid imaging results is desired by many cognitively impaired subjects and seems to be safe once appropriate education is delivered to the disclosing clinicians. Regarding clinical utility, increasing evidence points to a change in diagnosis via amyloid imaging in about 30% of cases, to an increase in diagnostic confidence in about 60% of cases, to a change in patient management in about 60% of cases, and specifically to a change in medication in about 40% of cases. Also, amyloid imaging results seem to have a relevant impact on caregivers. Further, initial simulation studies point to a potential positive effect on patient outcome and to cost effectiveness of amyloid imaging. These features, however, will require confirmation in prospective clinical trials. More work is also required to determine the clinical utility of amyloid imaging specifically in subjects with mild cognitive impairment and in comparison with or in conjunction with other Alzheimer disease biomarkers. In summary, the clinical use of amyloid imaging is being studied, and the currently available data point to a relevant clinical utility of this imaging technique. Ongoing research will determine whether this accurate and noninvasive approach to amyloid plaque load detection will translate into a benefit to cognitively impaired subjects. Wi th the successful development and subsequent clinical approval of 18 F-florbetapir, 18 F-florbetaben, and 18 F-flutemetamol, the nuclear imaging community has a set of b-amyloid aggregatetargeting PET tracers in hand for clinical use. They allow the in vivo detection or exclusion of neuritic b-amyloid plaques, one histopathologic hallmark in the neocortex of patients with Alzheimer disease (AD), which previously could be diagnosed only histopathologically after death. Of note, brain b-amyloid accumulation is known to be an early event in this disease (1) and is considered by many as the initial trigger of a cascade of other pathobiochemical and pathophysiologic alterations finally leading to neurodegeneration and related cognitive decline in AD (2).The emergence of amyloid imaging technology is hoped to fill a relevant diagnostic gap in the clinic in cognitively impaired subjects and in AD in particular. Most people would like to get a diagnosis when cognitive symptoms are identified (3). Conversely, dementia diagnosis is often missed and delayed (4,5). With regard to the therapeutic implications of an AD diagnosis, it was reported that older people are willing to accept the relevant side effects of AD-modifying therap...

18F‐Florbetaben PET/CT to Assess Alzheimer's Disease: A new Analysis Method for Regional Amyloid Quantification

“…Simultaneously, a positive amyloid PET result along with a high amyloid burden lead to a diagnosis of AD, although not in all instances . Major scientific societies and research centers are trying to develop more accurate PET imaging methods both qualitative and quantitative to define a positivity threshold that, in combination with other available clinical techniques, may lead to a biological diagnosis of AD …”

“…27 Major scientific societies and research centers are trying to develop more accurate PET imaging methods both qualitative and quantitative to define a positivity threshold that, in combination with other available clinical techniques, may lead to a biological diagnosis of AD. 28 The development of new classification algorithms is crucial to overcome these limits. An optimal amyloid PET imaging normalization should be based on coregistration of MRI images of patients for a correct morphological and quantitative functional evaluation for region of interest.…”

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“…The role of amyloid PET imaging in dementia has been extensively studied, and evidence on its diagnostic performance in prodromal, preclinical and clinical stages of dementia, as well on its prognostic value has been accumulated in large populations worldwide [6][7][8][9][10][11][12].…”

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