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Evaluation of 511 keV photon attenuation by a novel 32-channel phased array prospectively designed for cardiovascular hybrid PET/MRI imaging

Authors
  • Farag, Adam1, 2
  • Thompson, R. Terry1, 2
  • Thiessen, Jonathan D.1, 2, 2
  • Biernaski, Heather1
  • Prato, Frank S.1, 2, 2, 3
  • Théberge, Jean1, 2, 2, 3
  • 1 Lawson Health Research Institute, London, Ontario, Canada , London (Canada)
  • 2 Western University, London, Ontario, Canada , London (Canada)
  • 3 St. Joseph’s Health Care, London, Ontario, Canada , London (Canada)
Type
Published Article
Journal
European Journal of Hybrid Imaging
Publisher
Springer International Publishing
Publication Date
May 12, 2020
Volume
4
Issue
1
Identifiers
DOI: 10.1186/s41824-020-00076-w
Source
Springer Nature
Keywords
License
Green

Abstract

BackgroundSimultaneous cardiovascular imaging with positron emission tomography (PET) and magnetic resonance imaging (MRI) requires tools such as radio frequency (RF) phased arrays to achieve high temporal and spatial resolution in the MRI, as well as accurate quantification of PET. Today, high-density phased arrays (> 16 channels) used for cardiovascular PET/MRI are not designed to achieve low PET attenuation, and correcting the PET attenuation they cause requires off-line reconstruction, extra time and resources.PurposeMotivated by previous work assessing the MRI performance of a novel prospectively designed 32-channel phased array, this study assessed the PET image quality with this array in place. Guided by NEMA standards, PET performance was measured using global PET counts, regional background variation (BV), contrast recovery (CR) and contrast-to-noise ratio (CNR) for both the novel array and standard arrays (mMR 12-channel and MRI 32-channel). Nonattenuation-corrected (NAC) data from all arrays (and each part of the array) were processed and compared to no-array, and relative percentage difference (RPD) of the global means was estimated and reported for each part of the arrays. Attenuation correction (AC) of PET images (water in the phantom) using two approaches, MR-based AC map (MRAC) and dual-energy CT-based map (DCTAC), was performed, and RPD compared for each part of the arrays. Percent mean attenuation within regions of interests of the phantom images from each array were compared using a two-way analysis of variance (ANOVA).ResultsThe NAC data of the anterior part of the novel array recorded the least PET attenuation (≤ 2%); while the full novel array (anterior and posterior together) AC data, produced by MRAC and DCTAC approaches, recorded attenuation of 1.5 ± 2.9% and 0.0 ± 2.5%, respectively. The novel array PET count loss was significantly lower (p = 0.001) than those caused by the standard arrays.ConclusionsResults of this novel 32-channel cardiac array PET performance evaluation, together with its previously reported MRI performance assessment, suggest the novel array to be a strong alternative to the standard arrays currently used for cardiovascular hybrid PET/MRI imaging. It enables accurate PET quantification and high-temporal and spatial resolution for MR imaging.

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