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Neuroimaging in Nuclear Medicine
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
Anne Larsson Strömvall, Susanna Jakobson Mo
Amyloid imaging: The formation of amyloid plaques (Aβ plaques) and neurofibrillary tangles is a hallmark of Alzheimer’s disease. However, plaque formation may occur in healthy individuals and in other types of dementia. Therefore, the use of amyloid imaging warrants caution in patient selection and interpretation. Sometimes the clinical diagnosis of a dementing disorder is difficult if, for example, the onset or course or symptoms are not fully corroborant with established clinical criteria. However, the proper indications for amyloid imaging are still focus for research. The first and most well-documented amyloid tracer, the 11C Pittsburg compound B (Pib), has been used for several years, mainly in research settings. Lately, radiopharmaceuticals labelled with 18F for amyloid imaging for clinical practice (and research) have become commercially available: 18F-florbetaben (NeuraCeqTM), 18F florbetapir (Amyvid) and 18F-flutemetamol (Vizamyl). Up until now these are approved in Europe and the United States. The manufacturers have set up special recommendations for use and interpretation of each substance. For example, images should be interpreted only after a special training program provided by the manufacturer.
Quantitative analyses and case studies of hybrid PET-MRI imaging
Published in Yi-Hwa Liu, Albert J. Sinusas, Hybrid Imaging in Cardiovascular Medicine, 2017
Leon J. Menezes, Eleanor C. Wicks, Brian F. Hutton
Amyloidosis is a clinical disorder that arises from the aggregation of insoluble fibrous deposits of misfolded proteins. Deposition of fibrillary material and the toxic effects of precursor soluble intermediates result in progressive organ dysfunction, which manifest as heart failure with restrictive physiology (Gertz, Dispenzieri, and Sher 2014). The recent development of PET tracers for amyloid plaque identification in Alzheimer’s disease has generated potential interest in the evaluation of cardiac amyloidosis, a condition that is imaged using MRI (Fontana et al. 2014) and 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid (99mTc-DPD) SPECT (Hutt et al. 2014). 11C-PIB and 18F-Florbetapir have been used to depict systemic and cardiac amyloid (Antoni et al. 2013; Dorbala et al. 2014; Lee et al. 2015). Validation with T1 mapping and ECV measurements with simultaneous PET/MRI could possibly allow earlier diagnosis and treatment monitoring (Figure 16.4).
Alzheimer's Disease
Published in Marc E. Agronin, Alzheimer's Disease and Other Dementias, 2014
A newer diagnostic approach is to use PET tracers that bind to beta-amyloid plaques in the brain to reveal the relative pathologic load. Early developed compounds include Pittsburgh Compound B or PIB and 18F-FDDNP (Morris et al., 2009). Newer compounds include florbetapir, flutemetamol, and florbetaben, all of which utilize the isotope fluorine 18 with a half-life of 100 minutes—compared to PIB, which uses carbon 11 with a half-life of only 20 minutes (Vallabhajosula, 2011). Florbetapir and flutemetamol are currently on the market and can be used in individuals with known or suspected AD to confirm the presence of beta-amyloid plaques (Wood et al., 2010).
Novel strategies for the fight of Alzheimer’s disease targeting amyloid-β protein
Published in Journal of Drug Targeting, 2022
Yang Xie, Yan Wang, Shangfei Jiang, Xiaohong Xiang, Jianhua Wang, Linhong Ning
Present FDA-approved drugs available for AD includes acetylcholinesterase inhibitors for increasing the concentration of the neurotransmitter named acetylcholine (including tacrine, galantamine, donepezil, and rivastigmine), N-methyl-D-aspartate (NMDA) receptor antagonists (for inhibiting NMDA receptor-induced excitotoxicity, memantine) and their combination. But these drugs are limited to symptomatic relief rather than eradicating AD and the prognosis is poor [8]. In fact, efforts towards efficient AD-modifying therapies achieved little in previous clinical practice. Thus, recent research studies are focussed on designing promising novel therapies, in order to reduce the risk of AD course and even prevent the clinical occurrence of AD. The clinical trials to assess the effectiveness and safety of emerging AD therapeutic methods raise concern. Besides, some recent clinical trials conducted in AD patient have revealed a long preclinical stage before the onset of dementia (20 years or so), during which the Aβ accumulation process progressed slowly and went through three stages (including preclinical AD, mild cognitive impairment and eventual dementia) [9,10]. The result suggests that AD prevention trials should be conducted in both sporadic and familial individuals with potential AD, providing a new approach and a new treatment idea for AD modifying. On this premise, monitoring the level of Aβ concentration before symptoms develop in AD patients provides tremendous opportunity for AD prevention. In clinical trials, several diagnostic agents have received FDA approval in USA for clinical use such as 18F-florbetapir (18F-AV-45) which is a stilbene derivative developed by Kung’s research team [11].
A pilot study demonstrating cardiac uptake with 18F-florbetapir PET in AL amyloidosis patients with cardiac involvement
Published in Amyloid, 2018
Richa Manwani, Jo Page, Thirusha Lane, Maria Burniston, Annah Skillen, Helen J. Lachmann, Julian D. Gillmore, Marianna Fontana, Carol Whelan, Philip N. Hawkins, Thomas Wagner, Ashutosh D. Wechalekar
18F-florbetapir is licenced for detecting brain beta-amyloid deposits in Alzheimer’s disease. During the numerous studies of patients with Alzheimer’s disease, imaging was limited to the head only and no systemic imaging details are available. Dorbala et al. reported the first use of 18F-florbetapir in 9 patients with cardiac amyloidosis (5 AL, 4 ATTR) and 5 control subjects [8]. Increased myocardial tracer uptake was seen in all amyloid subjects and none of the controls.
Utility of the 18F-Florbetapir positron emission tomography in systemic amyloidosis
Published in Amyloid, 2018
Jaume Mestre-Torres, Carles Lorenzo-Bosquet, Gemma Cuberas-Borrós, Mercedes Gironella, Roser Solans-Laque, Andreu Fernández-Codina, Segundo Bujan-Rivas, Joan Castell-Conesa, Fernando Martínez-Valle
18F-Florbetapir PET appears to be a good diagnostic tool to identify the burden of the amyloidotic deposits in patients. It seems to be specific in patients diagnosed as having amyloidosis and has a good correlation with clinical findings, but standardized evaluation PET protocols are needed. Further studies are necessary to evaluate whether the PET scan is useful to assess or not the response to different treatments in patients with amyloidosis.