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Lookup NU author(s): Professor John-Paul TaylorORCiD, Emeritus Professor David Brooks, Dr Ross Maxwell, Dr Michael FirbankORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© The Author(s) 2026. Purpose: Positron emission tomography combined with magnetic resonance imaging (PET/MR) has not yet achieved the level of adoption of PET/CT. This study aimed to harmonise PET imaging protocols across a national PET/MR network and to quantitatively assess whether PET/MR can achieve reliability comparable to PET/CT. While previous PET test-retest studies have demonstrated good repeatability, they have typically been limited to small cohorts or restricted site configurations. Methods: We conducted a multi-site harmonisation and rigorous test-retest study across the network of eight PET/MR scanners. Thirty-seven healthy older participants (65-90 years) underwent harmonised one-hour amyloid PET/MR scans using either [F]flutemetamol or [F]florbetaben on two occasions. Retest scans were performed under conditions of same-site repeatability or multi-site reproducibility. Harmonised acquisition and reconstruction protocols were applied, and amyloid burden was quantified on the Centiloid (CL) scale. Results: CL values across 74 scans showed excellent test-retest agreement (ICC = 0.968), improving to 0.987 after exclusion of one attenuation correction related outlier. Mean test-retest variability was 2.58%. No statistically significant differences were observed across repeatability versus reproducibility conditions, scanner types, or tracers. CL measurements were highly consistent with three independent blinded visual reads. Conclusion: This study demonstrates that harmonised PET/MR achieves high reliability comparable to PET/CT. Although the accuracy of attenuation maps requires checks, this study supports the use of PET/MR for quantitative amyloid imaging in research and therapeutic trials, and provides a valuable open resource of image and raw PET/MR data for further methodological development.
Author(s): Markiewicz PJ, Thompson G, Wardlaw JM, Wimberley C, Ritchie C, Taylor J-P, Brooks D, Maxwell R, Firbank M, Hoggard N, Su L, Wild J, Hillel P, Rhodes-Bradford V, Parkes LM, O'Brien JT, Carter SF, Aigbirhio FI, Fryer T, Matthews PM, Malhotra P, Grey G, Hallett W, Ocal D, Dickson JC, De Vita E, Thomas DL, Fox NC, Krokos G, Mackewn JE, Marsden P, Hammers A, Herholz K, Barkhof F, Matthews JC
Publication type: Article
Publication status: Published
Journal: European Journal of Nuclear Medicine and Molecular Imaging
Year: 2026
Pages: Epub ahead of print
Online publication date: 29/04/2026
Acceptance date: 30/03/2026
Date deposited: 12/05/2026
ISSN (print): 1619-7070
ISSN (electronic): 1619-7089
Publisher: Springer Nature
URL: https://doi.org/10.1007/s00259-026-07885-4
DOI: 10.1007/s00259-026-07885-4
Data Access Statement: The image and raw PET/MR data will be available at https://www.dementiasplatform.uk/
PubMed id: 42050257
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