Amyloid‐PET quantification through the tracer‐independent Centiloid (CL) scale has emerged as an essential tool for the accurate measurement of amyloid‐β (Aβ) pathology in Alzheimer's disease (AD) patients. The AMYPAD consortium set out to integrate existing literature and recent work from the consortium to provide clinical context‐of‐use recommendations for the CL scale. Compared to histopathology, visual reads, and cerebrospinal fluid, CL quantification accurately reflects the amount of AD pathology. With high certainty, a CL value below 10 excludes the presence of Aβ pathology, while a value above 30 corresponds well with pathological amounts. Values falling in between these two cutoffs (“intermediate range”) are related to an increased risk of disease progression. Together, CL quantification is a valuable adjunct to visual assessments of amyloid‐PET images. An abnormal amyloid biomarker assessment is a key criterion to determine eligibility for anti‐amyloid disease‐modifying therapies, and amyloid‐PET quantification can add further value by precisely monitoring amyloid clearance, and hence guiding patient management decisions.Highlights: Centiloid (CL) quantification robustly reflects of the amount of Aβ pathology. CL < 10/CL > 30 reflects Aβ‐negativity/positivity thresholds with high certainty. CL quantification is a valuable adjunct to visual assessments of amyloid‐PET. CL quantification can support trial design and treatment management. CL quantification could support the identification of early or emerging Aβ pathology.

18F-GP1 is a novel positron emission tomography (PET) tracer that targets glycoprotein IIb/IIIa receptors on activated platelets. The study objective was to explore the feasibility of directly imaging acute arterial thrombosis (AAT) with 18F-GP1 PET/computed tomography (PET/CT) and to quantitatively assess 18F-GP1 uptake. Safety, biodistribution, pharmacokinetics and metabolism were also evaluated. Adult patients who had signs or symptoms of AAT or had recently undergone arterial intervention or surgery within 14 days prior to 18F-GP1 PET/CT were eligible for inclusion. The AAT focus was demonstrated by conventional imaging within the 5 days prior to 18F-GP1 administration. Whole-body dynamic 18F-GP1 PET/CT images were acquired for up to 140 min after injection of 250 MBq of 18F-GP1. Venous plasma samples were analysed to determine 18F-GP1 clearance and metabolite formation. Among the ten eligible patients assessed, underlying diseases were abdominal aortic aneurysm with endovascular repair (n = 6), bypass surgery and stent placement (n = 1), endarterectomy (n = 1), arterial dissection (n = 1) and acute cerebral infarction (n = 1). 18F-GP1 administration and PET/CT procedures were well tolerated, with no drug-related adverse events. All patients showed high initial 18F-GP1 uptake in the spleen, kidney and blood pool, followed by rapid clearance. Unmetabolised plasma 18F-GP1 levels peaked at 4 min post-injection and decreased over time until 120 min. The overall image quality was sufficient for diagnosis in all patients and AAT foci were detected in all participants. The 18F-GP1 uptake in AAT foci remained constant from 7 min after injection and began to separate from the blood pool after 20 min. The median standardised uptake value of AAT was 5.0 (range 2.4–7.9) at 120 min post-injection. The median ratio of standardised uptake value of AAT foci to the mean blood pool activity was 3.4 (range 2.0–6.3) at 120 min. 18F-GP1 is a safe and promising novel PET tracer for imaging AAT with a favourable biodistribution and pharmacokinetic profile. ClinicalTrials.gov identifier: NCT02864810 , Registered August 3, 2016.

Progressive supranuclear palsy (PSP) is a 4-repeat tauopathy movement disorder which can be imaged by the tau positron emission tomography (PET) tracer ¹⁸F-PI-2620. The in vivo diagnosis is currently established on clinical grounds and supported by midbrain atrophy estimation in structural magnetic resonance imaging (MRI). Here, we investigate whether ¹⁸F-PI-2620 tau PET has the potential to improve the imaging diagnosis of PSP. Methods: In this multi-center observational study, dynamic (0-60min p.i.) ¹⁸F-PI-2620 PET and structural MRI data of 36 patients with PSP, 22 with PSP-Richardson’s syndrome (PSP-RS) and 14 with clinical phenotypes other than RS, i.e. variant PSP (vPSP), and those of 10 age-matched healthy controls (HCs) were analyzed. The PET data underwent kinetic modeling which resulted in distribution volume ratio (DVR) images. These and the MRI images were visually assessed by three blinded experts each for typical PSP signs. Furthermore, established midbrain atrophy parameters were measured in structural MRI, and regional DVRs in typical tau-in-PSP target regions in the PET data. Results: Visual assessments discriminated PSP patients and HCs with an accuracy of 63% for MRI, and 80% for the combination of MRI and ¹⁸F-PI-2620 PET. As compared to patients of the PSP-RS subgroup, those of the vPSP subgroup profited more in terms of sensitivity from the addition of the visual ¹⁸F-PI-2620 PET to the visual MRI information (35% vs. 22%). In quantitative image evaluation, midbrain /pons area ratio and globus pallidus DVRs discriminated best between the PSP patients and HCs, with sensitivities/specificities of 83/90% for MRI, and 94/100% for the combination of MRI and ¹⁸F-PI-2620 PET. The gain of sensitivity by adding ¹⁸F-PI-2620 PET to MRI data was more marked in clinically less-affected as compared to more-affected patients (37% vs. 19% for visual, and 16% vs. 12% for quantitative image evaluation). Conclusion: These results provide evidence for an improved imaging-based PSP diagnosis by adding ¹⁸F-PI-2620 tau PET to structural MRI. This approach seems to be particularly promising at earlier disease stages and could be of value both for improving early clinical PSP diagnosis and for enriching PSP cohorts for trials of disease-modifying drugs.

PET/CT with (4S)-4-(3-[18F]fluoropropyl)-l-glutamate had high sensitivity for detecting primary brain cancers and brain metastases and could help predict primary brain tumor outcomes using informat... Background The PET tracer (4S)-4-(3-[18F]fluoropropyl)-l-glutamate (18F-FSPG) targets the system xC– cotransporter, which is overexpressed in various tumors. Purpose To assess the role of 18F-FSPG ...