ImportanceAmyloid positron emission tomography (PET) allows the direct assessment of amyloid deposition, one of the main hallmarks of Alzheimer disease. However, this technique is currently not widely reimbursed because of the lack of appropriately designed studies demonstrating its clinical effect.ObjectiveTo assess the clinical effect of amyloid PET in memory clinic patients.Design, Setting, and ParticipantsThe AMYPAD-DPMS is a prospective randomized clinical trial in 8 European memory clinics. Participants were allocated (using a minimization method) to 3 study groups based on the performance of amyloid PET: arm 1, early in the diagnostic workup (within 1 month); arm 2, late in the diagnostic workup (after a mean [SD] 8 [2] months); or arm 3, if and when the managing physician chose. Participants were patients with subjective cognitive decline plus (SCD+; SCD plus clinical features increasing the likelihood of preclinical Alzheimer disease), mild cognitive impairment (MCI), or dementia; they were assessed at baseline and after 3 months. Recruitment took place between April 16, 2018, and October 30, 2020. Data analysis was performed from July 2022 to January 2023.InterventionAmyloid PET.Main Outcome and MeasureThe main outcome was the difference between arm 1 and arm 2 in the proportion of participants receiving an etiological diagnosis with a very high confidence (ie, ≥90% on a 50%-100% visual numeric scale) after 3 months.ResultsA total of 844 participants were screened, and 840 were enrolled (291 in arm 1, 271 in arm 2, 278 in arm 3). Baseline and 3-month visit data were available for 272 participants in arm 1 and 260 in arm 2 (median [IQR] age: 71 [65-77] and 71 [65-77] years; 150/272 male [55%] and 135/260 male [52%]; 122/272 female [45%] and 125/260 female [48%]; median [IQR] education: 12 [10-15] and 13 [10-16] years, respectively). After 3 months, 109 of 272 participants (40%) in arm 1 had a diagnosis with very high confidence vs 30 of 260 (11%) in arm 2 (P < .001). This was consistent across cognitive stages (SCD+: 25/84 [30%] vs 5/78 [6%]; P < .001; MCI: 45/108 [42%] vs 9/102 [9%]; P < .001; dementia: 39/80 [49%] vs 16/80 [20%]; P < .001).Conclusion and RelevanceIn this study, early amyloid PET allowed memory clinic patients to receive an etiological diagnosis with very high confidence after only 3 months compared with patients who had not undergone amyloid PET. These findings support the implementation of amyloid PET early in the diagnostic workup of memory clinic patients.Trial RegistrationEudraCT Number: 2017-002527-21
Background:Polymyalgia rheumatica (PMR) is a relatively common disease among the elderly. None of the most common imaging techniques provides diagnostic certainty of PMR. 18F-fluoro-dexoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) may be a useful candidate as it can be used to visualize articular and periarticular FDG uptake at different locations, as well as associated large-vessel vasculitis (LVV), but its usefulness needs to be evaluated in the absence of large-scale case-control studies.Objectives:The purpose of this study was to determine the usefulness of FDG-PET/CT in diagnosing PMR and LVV.Methods:We analysed FDG-PET/CT scans performed between January 2015 and December 2019 on patients diagnosed with PMR. For comparisons, patients with PMR were matched 1:1 to controls according to age and sex. FDG-PET/CT scans had been performed on controls over the same period for diagnosis of cancer-associated stroke. FDG uptake was scored visually using a semi-quantitative analysis (score 0-3) for 17 articular or periarticular sites, as described by Sondag et al. [1], and for 13 vascular sites, as described by Slart et al. [2]. The case and control groups were compared using generalized linear mixed models (binomial distribution, logit function) for binary outcomes, and linear mixed models for continuous outcomes, with matched sets as a random effect. The optimal threshold for the number of sites with significant hyperfixation (score ≥ 2) was determined by maximizing the Youden index.Results:81 patients with a diagnosis of PMR and 81 controls were included (mean (SD) age 70.7 (9.8) years; 44.4% women). We found significant differences between the PMR and control groups at all articular or periarticular sites for: 1) FDG uptake score (p<0.0001); 2) number of patients per site with significant FDG uptake (score ≥ 2) (p<0.0001); 3) global FDG articular uptake scores (score 0-51) (31 [IQR, 21 to 37] versus 6 [IQR, 3 to 10], p<0.001); and 4) number of sites with significant FDG uptake (score ≥ 2) (score 0-17) (11 [IQR, 7 to 13] versus 1 [IQR, 0 to 2], p<0.001). Using ROC curve analysis (Figure 1), we found that the presence of 6 or more sites with significant FDG uptake (≥ 2) was associated with the diagnosis of PMR with a sensitivity of 84% and a specificity of 96% (AUC 0.96 [95% CI 0.93-0.99]). No significant differences in global FDG vascular uptake scores (score 0-39) or in number of patients with at least 1 significant uptake vascular site (score ≥ 2) were found between the PMR and control groups (1 [IQR, 0 to 4] versus 4 [0 to 6], p=0.06 and 8 (11.3%) versus 10 (14.1%), p=0.62 respectively).Figure 1.ROC curve analyzing performance of FDG-PET/CT for the diagnosis of PMR according to the number of sites with significant FDG uptake (≥ 2)Conclusion:Our results demonstrate that the FDG uptake score and the number of sites with significant FDG uptake could be relevant criteria for the diagnosis of PMR. However, unlike other authors, we found no evidence suggesting that FDG-PET/CT may be useful in diagnosing silent underlying LVV in patients with isolated PMR.References:[1]Sondag M, Guillot X, Verhoeven F, Blagosklonov O, Prati C, Boulahdour H, et al. Utility of 18F-fluoro-dexoxyglucose positron emission tomography for the diagnosis of polymyalgia rheumatica: a controlled study. Rheumatology (Oxford). 2016;55(8):1452-7.[2]Slart RHJA, Writing group, Reviewer group, Members of EANM Cardiovascular, Members of EANM Infection & Inflammation, Members of Committees, SNMMI Cardiovascular, Members of Council, PET Interest Group, et al. FDG-PET/CT(A) imaging in large vessel vasculitis and polymyalgia rheumatica: joint procedural recommendation of the EANM, SNMMI, and the PET Interest Group (PIG), and endorsed by the ASNC. Eur J Nucl Med Mol Imaging. 2018;45(7):1250-69.Disclosure of Interests:None declared
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