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Head-to-head comparison of a Si-photomultiplier-based and a conventional photomultiplier-based PET-CT system

Oddstig, Jenny LU ; Brolin, Gustav LU ; Trägårdh, Elin LU and Minarik, David LU (2021) In EJNMMI Physics 8(1).
Abstract

Background: A novel generation of PET scanners based on silicon (Si)-photomultiplier (PM) technology has recently been introduced. Concurrently, there has been development of new reconstruction methods aimed at increasing the detectability of small lesions without increasing image noise. The combination of new detector technologies and new reconstruction algorithms has been found to increase image quality. However, it is unknown to what extent the demonstrated improvement of image quality is due to scanner hardware development or improved reconstruction algorithms. To isolate the contribution of the hardware, this study aimed to compare the ability to detect small hotspots in phantoms using the latest generation SiPM-based PET/CT... (More)

Background: A novel generation of PET scanners based on silicon (Si)-photomultiplier (PM) technology has recently been introduced. Concurrently, there has been development of new reconstruction methods aimed at increasing the detectability of small lesions without increasing image noise. The combination of new detector technologies and new reconstruction algorithms has been found to increase image quality. However, it is unknown to what extent the demonstrated improvement of image quality is due to scanner hardware development or improved reconstruction algorithms. To isolate the contribution of the hardware, this study aimed to compare the ability to detect small hotspots in phantoms using the latest generation SiPM-based PET/CT scanner (GE Discovery MI) relative to conventional PM-based PET/CT scanner (GE Discovery 690), using identical reconstruction protocols. Materials and methods: Two different phantoms (NEMA body and Jasczcak) with fillable spheres (31 μl to 26.5 ml) and varying sphere-to-background-ratios (SBR) were scanned in one bed position for 15–600 s on both scanners. The data were reconstructed using identical reconstruction parameters on both scanners. The recovery-coefficient (RC), noise level, contrast (spherepeak/backgroundpeak-value), and detectability of each sphere were calculated and compared between the scanners at each acquisition time. Results: The RC-curves for the NEMA phantom were near-identical for both scanners at SBR 10:1. For smaller spheres in the Jaszczak phantom, the contrast was 1.22 higher for the DMI scanner at SBR 15:1. The ratio decreased for lower SBR, with a ratio of 1.03 at SBR 3.85:1. Regarding the detectability of spheres, the sensitivity was 98% and 88% for the DMI and D690, respectively, for SBR 15:1. For SBR 7.5, the sensitivity was 75% and 83% for the DMI and D690, respectively. For SBR 3.85:1, the sensitivity was 43% and 30% for the DMI and D690, respectively. Conclusion: Marginally higher contrast in small spheres was seen for the SiPM-based scanner but there was no significant difference in detectability between the scanners. It was difficult to detect differences between the scanners, suggesting that the SiPM-based detectors are not the primary reason for improved image quality.

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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Analogue PM-tubes, PET/CT, Phantom measurements, SiPM
in
EJNMMI Physics
volume
8
issue
1
article number
19
publisher
Springer
external identifiers
  • pmid:33630173
  • scopus:85101742462
ISSN
2197-7364
DOI
10.1186/s40658-021-00366-7
language
English
LU publication?
yes
id
7597e258-cd44-4e6e-9dcd-16875ccbccb9
date added to LUP
2022-03-08 13:37:56
date last changed
2024-07-07 10:03:36
@article{7597e258-cd44-4e6e-9dcd-16875ccbccb9,
  abstract     = {{<p>Background: A novel generation of PET scanners based on silicon (Si)-photomultiplier (PM) technology has recently been introduced. Concurrently, there has been development of new reconstruction methods aimed at increasing the detectability of small lesions without increasing image noise. The combination of new detector technologies and new reconstruction algorithms has been found to increase image quality. However, it is unknown to what extent the demonstrated improvement of image quality is due to scanner hardware development or improved reconstruction algorithms. To isolate the contribution of the hardware, this study aimed to compare the ability to detect small hotspots in phantoms using the latest generation SiPM-based PET/CT scanner (GE Discovery MI) relative to conventional PM-based PET/CT scanner (GE Discovery 690), using identical reconstruction protocols. Materials and methods: Two different phantoms (NEMA body and Jasczcak) with fillable spheres (31 μl to 26.5 ml) and varying sphere-to-background-ratios (SBR) were scanned in one bed position for 15–600 s on both scanners. The data were reconstructed using identical reconstruction parameters on both scanners. The recovery-coefficient (RC), noise level, contrast (sphere<sub>peak</sub>/background<sub>peak</sub>-value), and detectability of each sphere were calculated and compared between the scanners at each acquisition time. Results: The RC-curves for the NEMA phantom were near-identical for both scanners at SBR 10:1. For smaller spheres in the Jaszczak phantom, the contrast was 1.22 higher for the DMI scanner at SBR 15:1. The ratio decreased for lower SBR, with a ratio of 1.03 at SBR 3.85:1. Regarding the detectability of spheres, the sensitivity was 98% and 88% for the DMI and D690, respectively, for SBR 15:1. For SBR 7.5, the sensitivity was 75% and 83% for the DMI and D690, respectively. For SBR 3.85:1, the sensitivity was 43% and 30% for the DMI and D690, respectively. Conclusion: Marginally higher contrast in small spheres was seen for the SiPM-based scanner but there was no significant difference in detectability between the scanners. It was difficult to detect differences between the scanners, suggesting that the SiPM-based detectors are not the primary reason for improved image quality.</p>}},
  author       = {{Oddstig, Jenny and Brolin, Gustav and Trägårdh, Elin and Minarik, David}},
  issn         = {{2197-7364}},
  keywords     = {{Analogue PM-tubes; PET/CT; Phantom measurements; SiPM}},
  language     = {{eng}},
  number       = {{1}},
  publisher    = {{Springer}},
  series       = {{EJNMMI Physics}},
  title        = {{Head-to-head comparison of a Si-photomultiplier-based and a conventional photomultiplier-based PET-CT system}},
  url          = {{http://dx.doi.org/10.1186/s40658-021-00366-7}},
  doi          = {{10.1186/s40658-021-00366-7}},
  volume       = {{8}},
  year         = {{2021}},
}