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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
18F-flutemetamol images should be displayed with Sokoloff or rainbow or equivalent colour scale. In contrast, grey-scale images should be used for 18F-florbetaben and 18F florbetapir. Guidelines for the use of these tracers are set up by the Society of Nuclear Medicine and Molecular Imaging (SNMMI) [25].
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).
Degenerative Diseases of the Nervous System
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
James A. Mastrianni, Elizabeth A. Harris
Brain imaging should be obtained. Magnetic resonance imaging (MRI) scan is preferable, although computed tomography (CT) may be substituted. The principal purpose of brain imaging is to exclude masses, subdural hemorrhages, normal pressure hydrocephalus, severe cerebrovascular disease or vasculitis, and regional atrophy suggestive of other neurodegenerative processes. In the AD brain, imaging findings might include focal atrophy of the hippocampi and medial temporal lobes, as well as diffuse cortical atrophy most prominent in temporal and/or parietal lobes. These findings are helpful diagnostic clues, but may be very subtle in early AD. Coronal cuts on MRI allow for easier assessment of hippocampal volume. If the diagnosis remains unclear following initial MRI, functional imaging may be obtained with a positron emission tomographic (PET) scan. In the AD brain, FDG-PET scans demonstrate reduced metabolic activity (radiolabeled glucose utilization) over the temporal and parietal lobes. Notably, the US health insurer Medicare covers the cost of FDG-PET scans used to discriminate between AD and FTD. For patients under 65 years, a single photon emission tomography (SPECT) scan may be used, though this measures blood flow rather than direct metabolic activity, thereby providing an indirect measure of activity and has generally less sensitivity and specificity of FDG-PET. New PET tracers including F18-florbetapir, F18-florbetaben, and F18-flutemetamol have been developed to detect the presence of amyloid and quantify lesion burden in the brain. Amyloid PET scans are not covered by insurance companies or Medicare, making them inaccessible to most patients. Tracers for tau are currently in development and being used on a research basis.
Quantification of cardiac amyloid with [18F]Flutemetamol in patients with V30M hereditary transthyretin amyloidosis
Published in Amyloid, 2020
Sofia Möckelind, Jan Axelsson, Björn Pilebro, Per Lindqvist, Ole B. Suhr, Torbjörn Sundström
For imaging of amyloid in patients with Alzheimer’s disease, a class of positron emission tomography (PET) tracers, originating from thioflavin T, have been developed. The original Carbon-11-labeled Pittsburgh compound B (11C-PIB) visualises amyloid deposition in the brain at an early stage of Alzheimer’s disease [20]. 11C-PIB and a fluorine-based tracer [18F]Florbetapir have in a few studies shown amyloid uptake outside of the brain [21] and both tracers have in different studies shown a high affinity for cardiac deposits in ATTR amyloidosis [22–24]. Pilebro et al. showed that ATTR fibril type B patients had a higher heart uptake of 11C-PIB [16] than those with fibril type A. [18F]Flutemetamol [25] has shown a similar uptake in the brain of patients with Alzheimer’s disease when compared to 11C-PIB [26]. A case study suggests [18F]Flutemetamol could be used in diagnostics of cardiac amyloidosis [27].
Examining the Relationship between a Verbal Incidental Learning Measure from the WAIS-IV and Neuroimaging Biomarkers for Alzheimer’s Pathology
Published in Developmental Neuropsychology, 2020
Dustin B. Hammers, Amanda Kucera, Robert J. Spencer, Tracy J. Abildskov, Zane G. Archibald, John M. Hoffman, Elizabeth A. Wilde
Positron emission tomography (PET) imaging was performed using the diagnostic radiopharmaceutical 18 F-Flutemetamol to estimate beta-amyloid neuritic plaque density in adult patients with cognitive impairment. The technical aspects of the PET imaging procedure have been previously described (Duff et al., 2013; Hammers et al., 2017). 18F-Flutemetamol was produced under PET cGMP standards and the studies were conducted under an approved FDA Investigational New Drug application. In brief, the 18F-Flutemetamol-PET Imaging procedure was performed 90 minutes after the injection of 185 mBq (5 mCi) of 18F-Flutemetamol. Emission imaging time was approximately 20 minutes. Eight of the scans were obtained on a GE Discovery 710 tomograph and one individual was scanned on a GE Discovery ST tomograph. The inherent resolution between the two tomographs was different however the native slice thickness between the two scanners was similar. Volumes of interest were automatically generated with CortexID Suite analysis software (GE Healthcare). 18F-Flutemetamol binding was analyzed using a regional semi-quantitative technique described by Vandenberghe et al. (2010) and refined by Thurfjell et al. (2014). Using this methodology, semi-quantitative regional (prefrontal, anterior cingulate, precuneus/posterior cingulate, parietal, mesial temporal, lateral temporal, occipital, sensorimotor, cerebellar gray matter, and whole cerebellum) and global composite standardized uptake value ratios (SUVRs) in the cerebral cortex were generated automatically and normalized to the pons using the CortexID Suite software (Lundqvist et al., 2013).
The flutemetamol analogue cyano-flutemetamol detects myocardial AL and ATTR amyloid deposits: a post-mortem histofluorescence analysis
Published in Amyloid, 2023
Eric E. Abrahamson, Robert F. Padera, Julie Davies, Gill Farrar, Victor L. Villemagne, Sharmila Dorbala, Milos D. Ikonomovic
Another possible source of false negative results in amyloid PET studies of cardiac amyloidosis could be related to different scanning protocols (e.g. delayed timing of the image acquisition at a time when the radiotracer may be washed out of the myocardium). The β-amyloid tracer PET studies performed thus far on subjects with cardiac amyloidosis demonstrate that the degree of ligand retention by cardiac amyloid fibrils may be dependent on the time frame during which the images are obtained. Prior studies using [11C]PiB, from which flutemetamol was derived and labeled with fluorine-18, at earlier imaging times demonstrated its value in imaging AL and ATTR cardiac amyloidosis [27,32]. Multiple studies using [18F]florbetapir, [18F]florbetaben and [18F]flutemetamol imaging have used dynamic imaging protocols or early imaging (within the first 20–30 min), and have shown cardiac uptake in patients with AL and ATTR cardiac amyloidosis [33,39,42,44,46,47,71,72]. These results contrast with one study where static cardiac images obtained at a late timeframe (mean 78 min) have documented limited sensitivity [45]. Notably, to the best of our knowledge, there are no other studies using [18F]florbetapir or [18F]florbetaben to image patients with cardiac amyloidosis using late imaging at mean of 78 min post injection. Future studies should aim to explore the binding kinetics of PET amyloid ligands in cardiac amyloidosis more systematically, ideally in a multi-center studies. To determine the optimal timing for the PET acquisition, dynamic scanning over a long scan period with multiple reconstructions may be required. Alternatively, perfusion deficits could reduce or prevent radioligands from accessing their target in the cardiac interstitium. In this regard, in several subjects in our study intramyocardial arterioles had cyano-flutemetamol labeled amyloid deposits which in some instances appeared to completely occlude the vessel lumen (Figure 1(D)).