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Background: Despite increased recognition of cognitive impairment in Multiple System Atrophy (MSA), its neuroanatomical correlates are not well defined. We aimed to explore cognitive profiles in MSA with predominant parkinsonism (MSA-P) and Parkinson's disease (PD) and their relationship to frontostriatal structural and metabolic changes. Methods: Detailed clinical and neuropsychological evaluation was performed together with diffusion tensor imaging (DTI) and [ 18F]-fluoro-deoxyglucose positron emission tomography ([ 18F]-FDG-PET) in patients with MSA-P (n = 11) and PD (n = 11). We compared clinical and neuropsychological data to healthy controls (n = 9) and correlated neuropsychological data with imaging findings in MSA-P and PD. Results: Patients with MSA-P showed deficits in executive function (Trail Making Test B-A) and scored higher in measures of depression and anxiety compared to those with PD and healthy controls. Widespread frontostriatal white matter tract reduction in fractional anisotropy was seen in MSA-P and PD compared to an imaging control group. Stroop Test interference performance correlated with [ 18F]-FDG uptake in the bilateral dorsolateral prefrontal cortex (DLPFC) and with white matter integrity between the striatum and left inferior frontal gyrus (IFG) in PD. Trail Making Test performance correlated with corticostriatal white matter integrity along tracts from the bilateral IFG in MSA-P and from the right DLPFC in both groups. Conclusion: Executive dysfunction was more prominent in patients with MSA-P compared to PD. DLPFC metabolism and frontostriatal white matter integrity seem to be a driver of executive function in PD, whereas alterations in corticostriatal white matter integrity may contribute more to executive dysfunction in MSA-P.

Acknowledgements: This work received financial support from the EU/EFPIA Innovative Medicines Initiative Joint Undertaking EMIF grant agreement no. 115372. This work also received in-kind sponsoring from GE Healthcare in the form of flutemetamol cassettes for production of the radiotracer at the Wolfson Molecular Imaging Centre using GE’s FASTlab system. This work has also been supported by the Erasmus+ programme of the European Union. The European Commission support for the production of this publication does not constitute an endorsement of the contents which reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein. SFC is supported by the NIHR Cambridge Biomedical Research Centre (BRC-1215-20014). The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care. We are very grateful to the individuals who participated in this study and their long dedication to ageing research. This study also would not have been possible without operational support colleagues at the Wolfson Molecular Imaging Centre and the research nurses and radiographers at the NIHR Manchester Clinical Research Facility within Manchester Royal Infirmary., Funder: EU/EFPIA Innovative Medicines Initiative Joint Undertaking EMIF grant agreement #°115372 NIHR Cambridge Biomedical Research Centre (BRC-1215-20014), Amyloid-beta (Aβ) deposition is common in cognitively unimpaired (CU) elderly >85 years. This study investigated amyloid distribution and evaluated three published in vivo amyloid-PET staging schemes from a cognitively unimpaired (CU) cohort aged 84.9 ± 4.3 years (n = 75). SUV-based principal component analysis (PCA) was applied to 18F-flutemetamol PET data to determine an unbiased regional covariance pattern of tracer uptake across grey matter regions. PET staging schemes were applied to the data and compared to the PCA output. Concentration of p-tau181 was measured in blood plasma. The PCA revealed three distinct components accounting for 91.2% of total SUV variance. PC1 driven by the large common variance of uptake in neocortical and striatal regions was significantly positively correlated with global SUVRs, APOE4 status and p-tau181 concentration. PC2 represented mainly non-specific uptake in typical amyloid-PET reference regions, and PC3 the occipital lobe. Application of the staging schemes demonstrated that the majority of the CU cohort (up to 93%) were classified as having pathological amount and distribution of Aβ. Good correspondence existed between binary (+/-) classification and later amyloid stages, however, substantial differences existed between schemes for low stages with 8-17% of individuals being unstageable, i.e., not following the sequential progression of Aβ deposition. In spite of the difference in staging outcomes there was broad spatial overlap between earlier stages and PC1, most prominently in default mode network regions. This study critically evaluated the utility of in vivo amyloid staging from a single PET scan in CU elderly and found that early amyloid stages could not be consistently classified. The majority of the cohort had pathological Aβ, thus, it remains an open topic what constitutes abnormal brain Aβ in the oldest-old and what is the best method to determine that.

A 65-year-old man was referred to a local memory clinic with memory complaints but clinical assessment found no abnormalities. When he presented two years later to our clinic social disinhibition, reduced empathy, poor judgment and hoarding had become obvious. He showed no insight. He had ischemic heart disease and was on preventive treatment. His mother died aged 97 suffering from dementia. Neurological examination was normal. During neuropsychological examination he exhibited verbal and behavioral disinhibition, inattention, emotional blunting and unconcern. He had prominent difficulties in abstraction, set shifting and sequencing with significant impact on memory tests (table1). A clinical diagnosis of behavioral variant FTD (bvFTD) was made. MRI (figure A) showed right more than left-sided temporal atrophy, bilateral frontal and milder parietal atrophy. Fluorodeoxyglucose (FDG)-PET (figure B) demonstrated fronto-temporal hypometabolism. Metabolism in the posterior cingulate was normal. He was homozygous for the APOE ε4 allele and negative for the C9orf72 expansion and mutations in MAPT, GRN, PSEN1, and APP. [18F]-Florbetapir PET (figure C) revealed increased tracer binding in all cortical regions corresponding to a centiloid value of 74%.

Recent studies in neurodegenerative conditions have increasingly highlighted that the same neuropathology can trigger different clinical phenotypes or, vice-versa, that similar phenotypes can be triggered by different neuropathologies. This evidence has called for the adoption of a pathology spectrum-based approach to study neurodegenerative proteinopathies. These conditions share brain deposition of abnormal protein aggregates, leading to aberrant biochemical, metabolic, functional, and structural changes. Positron emission tomography (PET) is a well-recognized and unique tool for the in vivo assessment of brain neuropathology, and novel PET techniques are emerging for the study of specific protein species. Today, key applications of PET range from early research and clinical diagnostic tools to their use in clinical trials for both participants screening and outcome evaluation. This position article critically reviews the role of distinct PET molecular tracers for different neurodegenerative proteinopathies, highlighting their strengths, weaknesses, and opportunities, with special emphasis on methodological challenges and future applications. (C) 2019 the Alzheimer's Association. Published by Elsevier Inc. All rights reserved.

Neuroinflammation, a key early pathomechanistic alteration of Alzheimer’s disease, may represent either a detrimental or a compensatory mechanism or both (according to the disease stage). YKL-40, a glycoprotein highly expressed in differentiated glial cells, is a candidate biomarker for in vivo tracking neuroinflammation in humans. We performed a longitudinal study in a monocentric cohort of cognitively healthy individuals at risk for Alzheimer’s disease exploring whether age, sex, and the apolipoprotein E e4 allele affect plasma YKL-40 concentrations. We investigated whether YKL-40 is associated with brain amyloid-β (Aβ) deposition, neuronal activity, and neurodegeneration as assessed via neuroimaging biomarkers. Finally, we investigated whether YKL-40 may predict cognitive performance. We found an age-associated increase of YKL-40 and observed that men display higher concentrations than women, indicating a potential sexual dimorphism. Moreover, YKL-40 was positively associated with memory performance and negatively associated with brain Aβ deposition (but not with metabolic signal). Consistent with translational studies, our results suggest a potentially protective effect of glia on incipient brain Aβ accumulation and neuronal homeostasis.

Various biomarkers are available to support the diagnosis of neurodegenerative diseases in clinical and research settings. Among the molecular imaging biomarkers, amyloid-PET, which assesses brain amyloid deposition, and18F-fluorodeoxyglucose (18F-FDG) PET, which assesses glucose metabolism, provide valuable and complementary information. However, uncertainty remains regarding the optimal timepoint, combination, and an order in which these PET biomarkers should be used in diagnostic evaluations because conclusive evidence is missing. Following an expert panel discussion, we reached an agreement on the specific use of the individual biomarkers, based on available evidence and clinical expertise. We propose a diagnostic algorithm with optimal timepoints for these PET biomarkers, also taking into account evidence from other biomarkers, for early and differential diagnosis of neurodegenerative diseases that can lead to dementia. We propose three main diagnostic pathways with distinct biomarker sequences, in which amyloid-PET and18F-FDG-PET are placed at different positions in the order of diagnostic evaluations, depending on clinical presentation. We hope that this algorithm can support diagnostic decision making in specialist clinical settings with access to these biomarkers and might stimulate further research towards optimal diagnostic strategies.

Purpose: The combination of positron emission tomography (PET) with magnetic resonance imaging (MRI) may enable novel research in the field of dementia. MR data is commonly used in the analysis of PET data for dementia due to its anatomical information and good soft tissue contrast. PET image reconstruction is currently performed independently of MRI data and the images typically suffer from low resolution, poor signal-to-noise ratio and count dependent bias, due to random error in acquired data and the reconstruction process which is ill conditioned. The aim of this research is to investigate the benefit of using anatomical information from MR data within PET image reconstruction, applied to dementia research. Methods: Real PET and MRI patient data of 5 FDG scans of a healthy elderly volunteers, were used in order to create realistic ground truth images of the distribution of matter and activity for these individuals. These ground truth images underwent a Monte-Carlo simulation using SimSET, in order to generate simulated raw data of the high research resolution tomograph (HRRT) PET scanner. The simulations were validated by comparing the reconstructed images to real HRRT data and focusing on image resolution. A comparison of partial volume correction (PVC) of PET data applied within image reconstruction with the conventional approach of applying it post-reconstruction was conducted with typical count levels in order to evaluate the hypothesis that there would be benefit of applying PVC within image reconstruction. Results: Results showed a little improvement in the recovered activity values is seen when using Lucy-Richardson deconvolution both post and within the image reconstruction. Similarly the use of RM modelling showed little benefit. Differences were observed when using Rousset PVC, with larger differences observed when interleaved with reconstruction. Generally the used of Rousset PVC within reconstruction resulted in a decrease in the bias (average error) for large cortical regions, but an increase in bias was observed for small regions and there were apparent region specific and patient specific variations in the observed bias. Conclusions: The benefit of applying PVC as a reconstruction based method showed to be minimal. A region specific bias was observed for most of the reconstruction methods, either applied within or post image reconstruction. Further work is needed to evaluate the benefit of applying PVC methods for high resolution scanners.

International audience; The Precision Neurology development process implements systems theory with system biology and neurophysiology in a parallel, bidirectional research path: a combined hypothesis-driven investigation of systems dysfunction within distinct molecular, cellular, and large-scale neural network systems in both animal models as well as through tests for the usefulness of these candidate dynamic systems biomarkers in different diseases and subgroups at different stages of pathophysiological progression. This translational research path is paralleled by an “omics”-based, hypothesis-free, exploratory research pathway, which will collect multimodal data from progressing asymptomatic, preclinical, and clinical neurodegenerative disease (ND) populations, within the wide continuous biological and clinical spectrum of ND, applying high-throughput and high-content technologies combined with powerful computational and statistical modeling tools, aimed at identifying novel dysfunctional systems and predictive marker signatures associated with ND. The goals are to identify common biological denominators or differentiating classifiers across the continuum of ND during detectable stages of pathophysiological progression, characterize systems-based intermediate endophenotypes, validate multi-modal novel diagnostic systems biomarkers, and advance clinical intervention trial designs by utilizing systems-based intermediate endophenotypes and candidate surrogate markers. Achieving these goals is key to the ultimate development of early and effective individualized treatment of ND, such as Alzheimer’s disease. The Alzheimer Precision Medicine Initiative (APMI) and cohort program (APMI-CP), as well as the Paris based core of the Sorbonne University Clinical Research Group “Alzheimer Precision Medicine” (GRC-APM) were recently launched to facilitate the passageway from conventional clinical diagnostic and drug development toward breakthrough innovation based on the investigation of the comprehensive biological nature of aging individuals. The APMI movement is gaining momentum to systematically apply both systems neurophysiology and systems biology in exploratory translational neuroscience research on ND.

Purpose: To assess the clinical utility of 18F-Fluorodeoxyglucose positron emission tomography (FDG-PET) for detection of early signs of neurodegeneration in conditions of increased risk for Alzheimer’s disease (AD) as defined by: subjective cognitive decline (SCD), evidence of cerebral amyloid-pathology, apolipoprotein E (APOE) ε4-positive genotype, or autosomal dominant forms of AD (ADAD) in asymptomatic stages. Methods: A comprehensive literature search was conducted using the PICO model to extract evidence from relevant studies. An expert panel then voted using the Delphi method on three different diagnostic scenarios. Results: The level of empirical study evidence for the use of FDG-PET to detect meaningful early signs of neurodegeneration was considered to be poor for ADAD and lacking for SCD and asymptomatic persons at risk, based on APOE ε4-positive genotype or cerebral amyloid pathology. Consequently, and consistent with current diagnostic criteria, panelists decided not to recommend routine clinical use of FDG-PET in these situations and to currently mainly reserve it for research purposes. Conclusion: Currently, there is limited evidence on which to base recommendations regarding the clinical routine use of FDG-PET to detect diagnostically meaningful early signs of neurodegeneration in asymptomatic subjects with ADAD, with APOE ε4-positive genotype, or with cerebral amyloid pathology, and in subjects with SCD. Future prospective studies are warranted and in part already ongoing, aiming to assess the added value of FDG-PET in this context beyond research applications.

The use of biomarkers (BMs) for accurate diagnosis of Alzheimer's disease (AD) has been proposed by recent diagnostic criteria; however, their maturity is not sufficient to grant implementation in the clinical routine. A proper diagnostic process requires not only confirmation of the disease but also the exclusion of similar disorders entering differential diagnosis, like dementia with Lewy bodies (DLB). This review is aimed at evaluating the clinical validity of 123I-ioflupane brain single photon emission tomography and 123I-MIBG cardiac scintigraphy as imaging BMs for DLB. For this purpose, we used an adapted version of the 5-phase oncology framework for BMs development. A review of the literature was conducted using homogenous search criteria with other BMs addressed in parallel reviews. Results of our literature search showed that the rationale for the use of both BMs in the differential diagnosis of DLB and AD is strong (phase 1) and that they allow a good discrimination ability (phase 2), but studies investigating BMs distribution antemortem and postmortem on pathology are lacking. Moreover, thresholds for test positivity have not been defined for 123I-MIBG. The 2 BMs have not been yet assessed in early phases of DLB and AD (phase 3). No phase 4 and phase 5 studies have so far been carried out. This review highlights the priorities to address in future investigations to enable the proper use of 123I-ioflupane and 123I-MIBG for the differential diagnosis of dementia.

Contains fulltext : 229556.pdf (Publisher’s version ) (Closed access) Various biomarkers are available to support the diagnosis of neurodegenerative diseases in clinical and research settings. Among the molecular imaging biomarkers, amyloid-PET, which assesses brain amyloid deposition, and (18)F-fluorodeoxyglucose ((18)F-FDG) PET, which assesses glucose metabolism, provide valuable and complementary information. However, uncertainty remains regarding the optimal timepoint, combination, and an order in which these PET biomarkers should be used in diagnostic evaluations because conclusive evidence is missing. Following an expert panel discussion, we reached an agreement on the specific use of the individual biomarkers, based on available evidence and clinical expertise. We propose a diagnostic algorithm with optimal timepoints for these PET biomarkers, also taking into account evidence from other biomarkers, for early and differential diagnosis of neurodegenerative diseases that can lead to dementia. We propose three main diagnostic pathways with distinct biomarker sequences, in which amyloid-PET and (18)F-FDG-PET are placed at different positions in the order of diagnostic evaluations, depending on clinical presentation. We hope that this algorithm can support diagnostic decision making in specialist clinical settings with access to these biomarkers and might stimulate further research towards optimal diagnostic strategies.

Background After the success of PET/CT as a clinical diagnostic tool, the introduction of PET/MRI is a natural development aimed at further improving combined diagnostic imaging and reduced ionising radiation dose for half-body imaging. As with PET and CT, the combination of PET and MRI presents a series of issues that need to be addressed regarding workforce training and education. At present, there is a lack of agreement over the competencies, training requirements and educational pathways needed for PET/MRI operation. In the UK, following the establishment of the MR-PET imaging network, a task force was created to investigate the status of the workforce training, identify gaps and make recommendations regarding staff training. To do this, we ran a national survey on the status of the workforce training and the local practices across the UK’s seven PET/MRI sites, reviewed the literature, and convened a panel of experts, to assess all the evidence and make recommendations regarding PET/MRI competencies and training of nuclear medicine technologists and radiographers. Results There is limited literature available specifically on competencies and training for technologists and radiographers. The recommendations on the topic needed revisiting and adapting to the UK MR-PET network. The online survey confirmed the need for developing PET/MRI competencies and training pathways. Local organisational structures and practices were shared across the seven sites, based on models derived from experience outside the UK. The panel of experts agreed on the need for PET/MRI competencies and training strategies. Professional organisations started collaborative discussions with partners from both Nuclear Medicine and Radiography to set training priorities. Multidisciplinary collaboration and partnership were suggested as a key to a successful implementation of competencies and training. Conclusions The report identified the need for establishing competencies for the PET/MRI workforce, particularly for technologists and radiographers. It also helped defining these competencies as well as identifying the demand for bespoke training and the development of local and national courses to be implemented to fulfil this new training need.

Various biomarkers are available to support the diagnosis of neurodegenerative diseases in clinical and research settings. Among the molecular imaging biomarkers, amyloid-PET, which assesses brain amyloid deposition, and

The benefit of partial volume correction (PVC) within and post image reconstruction for high resolution PET scanners was examined. Listmode data from a realistic simulation of the HRRT that represented radioactivity and matter distributions for amyloid negative, amyloid positive and FDG scans in the head were conducted and reconstructed using the HRRT community software. PVC methods of Lucy-Richardson deconvolution and Rousset were applied both within and post reconstruction. Hammers’ atlas brain regions that were predominantly both grey and white matter were applied to the images and the ground truth. For all three simulated scans (FDG, amyloid negative and amyloid positive) there was very little benefit of Lucy-Richardson deconvolution both within and post reconstruction. For Rousset PVC, both within and post image reconstruction, there was a reduction on average in the bias. However, a large region-specific bias was observed which was larger for the small regions and when PVC was applied within image reconstruction. This work casts doubt on the benefit of PVC for high resolution PET scanners with further work needed to evaluate whether PVC is of value.

Introduction Blood-based biomarkers of pathophysiological brain amyloid β (Aβ) accumulation, particularly for preclinical target and large-scale interventions, are warranted to effectively enrich Alzheimer's disease clinical trials and management. Methods We investigated whether plasma concentrations of the Aβ 1–40 /Aβ 1–42 ratio, assessed using the single-molecule array (Simoa) immunoassay, may predict brain Aβ positron emission tomography status in a large-scale longitudinal monocentric cohort (N = 276) of older individuals with subjective memory complaints. We performed a hypothesis-driven investigation followed by a no-a-priori hypothesis study using machine learning. Results The receiver operating characteristic curve and machine learning showed a balanced accuracy of 76.5% and 81%, respectively, for the plasma Aβ 1–40 /Aβ 1–42 ratio. The accuracy is not affected by the apolipoprotein E ( APOE ) e4 allele, sex, or age. Discussion Our results encourage an independent validation cohort study to confirm the indication that the plasma Aβ 1–40 /Aβ 1–42 ratio, assessed via Simoa, may improve future standard of care and clinical trial design.

Objective To characterize metabolic correlates of working memory impairment in clinically defined subtypes of early-onset Alzheimer's disease. Background Established models of working memory suggest a key role for frontal lobe function, yet the association in Alzheimer's disease between working memory impairment and visuospatial and language symptoms suggests that temporoparietal neocortical dysfunction may be responsible. Methods Twenty-four patients with predominantly early-onset Alzheimer's disease were clinically classified into groups with predominantly amnestic, multidomain or visual deficits. Patients underwent neuropsychological evaluation focused on the domains of episodic and working memory, T1-weighted magnetic resonance imaging and brain fluorodeoxyglucose positron emission tomography. Fluorodeoxyglucose positron emission tomography data were analysed by using a region-of-interest approach. Results Patients with multidomain and visual presentations performed more poorly on tests of working memory compared with amnestic Alzheimer's disease. Working memory performance correlated with glucose metabolism in left-sided temporoparietal, but not frontal neocortex. Carriers of the apolipoprotein E4 gene showed poorer episodic memory and better working memory performance compared with noncarriers. Conclusions Our findings support the hypothesis that working memory changes in early-onset Alzheimer's disease are related to temporoparietal rather than frontal hypometabolism and show dissociation from episodic memory performance. They further support the concept of subtypes of Alzheimer's disease with distinct cognitive profiles due to prominent neocortical dysfunction early in the disease course. Copyright © 2017 John Wiley & Sons, Ltd.

A previous review published in 2012 demonstrated the role of clinical PET for diagnosis and management of brain tumors using mainly FDG, amino acid tracers, and 18F-fluorothymidine. This review provides an update on clinical PET studies, most of which are motivated by prediction of prognosis and planning and monitoring of therapy in gliomas. For FDG, there has been additional evidence supporting late scanning, and combination with 13N ammonia has yielded some promising results. Large neutral amino acid tracers have found widespread applications mostly based on 18F-labeled compounds fluoroethyltyrosine and fluorodopa for targeting biopsies, therapy planning and monitoring, and as outcome markers in clinical trials. 11C-alpha-methyltryptophan (AMT) has been proposed as an alternative to 11C-methionine, and there may also be a role for cyclic amino acid tracers. 18F-fluorothymidine has shown strengths for tumor grading and as an outcome marker. Studies using 18F-fluorocholine (FCH) and 68Ga-labeled compounds are promising but have not yet clearly defined their role. Studies on radiotherapy planning have explored the use of large neutral amino acid tracers to improve the delineation of tumor volume for irradiation and the use of hypoxia markers, in particular 18F-fluoromisonidazole. Many studies employed the combination of PET with advanced multimodal MR imaging methods, mostly demonstrating complementarity and some potential benefits of hybrid PET/MR.

See Herholz (doi:10.1093/brain/awx340) for a scientific commentary on this article.

ObjectivesWith the tools available currently, confirming the diagnosis of inclusion body myositis (IBM) can be difficult. Many patients are initially misdiagnosed with polymyositis (PM). In this observational study at a UK adult neuromuscular centre, we investigated whether amyloid positron emission tomography could differentiate between IBM and PM.MethodsTen patients with IBM and six with PM underwent clinical review, [18F]florbetapir positron emission tomography and MRI of skeletal musculature. Differences in [18F]florbetapir standardised uptake value ratios in skeletal muscle regions of interest were evaluated. Relationships between [18F]florbetapir standardised uptake value ratios and measures of disease severity (clinical and by MRI of skeletal muscle) were assessed.Results[18F]florbetapir standardised uptake value ratios were significantly higher in those with IBM compared with PM for all assessed regions (total-[18F]florbetapir standardised uptake value ratio 1.45 (1.28 to 2.05) vs 1.01 (0.80 to 1.22), p=0.005). For total-[18F]florbetapir standardised uptake value ratios≥1.28, sensitivity and specificity for IBM was 80% and 100%, respectively.Conclusions[18F]florbetapir amyloid positron emission tomography differentiates IBM from PM. Successful development could facilitate accurate diagnosis, inclusion in clinical trials and help avoid unnecessary exposure to potentially harmful treatments.

Purpose The PET tracer [18F]florbetapir is a specific fibrillar amyloid-beta (Aβ) biomarker. During the late scan phase (> 40 min), it provides pathological information about Aβ status. Early scan phase (0–10 min) can provide FDG-‘like’ information. The current investigation tested the feasibility of using florbetapir as a dual-phase biomarker in behavioural variant frontotemporal dementia (bvFTD). Methods Eight bvFTD patients underwent [18F]florbetapir and [18]FDG-PET scans. Additionally, ten healthy controls and ten AD patients underwent florbetapir-PET only. PET data were acquired dynamically for 60-min post-injection. The bvFTD PET data were used to define an optimal time window, representing blood flow-related pseudo-metabolism (‘pseudo-FDG’), of florbetapir data that maximally correlated with the corresponding real FDG SUVR (40–60 min) in a composite neocortical FTD region. Results A 2 to 5-min time window post-injection of the florbetapir-PET data provided the largest correlation (Pearson’s r = 0.79, p = 0.02) to the FDG data. The pseudo-FDG images demonstrated strong internal consistency with actual FDG data and were also visually consistent with the bvFTD patients’ hypometabolic profiles. The ability to identify bvFTD from blind visual rating of pseudo-FDG images was consistent with previous reports using FDG data (sensitivity = 75%, specificity = 85%). Conclusions This investigation demonstrates that early phase florbetapir uptake shows a reduction of frontal lobe perfusion in bvFTD, similar to metabolic findings with FDG. Thus, dynamic florbetapir scans can serve as a dual-phase biomarker in dementia patients to distinguish FTD from AD and cognitively normal elderly, removing the need for a separate FDG-PET scan in challenging dementia cases. Electronic supplementary material The online version of this article (10.1007/s00259-018-4238-2) contains supplementary material, which is available to authorized users.