Impact of acquisition time and penalizing factor in a block-sequential regularized expectation maximization reconstruction algorithm on a Si-photomultiplier-based PET-CT system for <sup>18</sup>F-FDG

Trägårdh, Elin; Minarik, David; Almquist, Helén; Bitzén, Ulrika; Garpered, Sabine; Hvittfelt, Erland; Olsson, Berit; Oddstig, Jenny

Impact of acquisition time and penalizing factor in a block-sequential regularized expectation maximization reconstruction algorithm on a Si-photomultiplier-based PET-CT system for ¹⁸F-FDG

Mark

Trägårdh, Elin ^LU ; Minarik, David ^LU ; Almquist, Helén ^LU ; Bitzén, Ulrika ^LU ; Garpered, Sabine ^LU ; Hvittfelt, Erland ^LU

; Olsson, Berit ^LU and Oddstig, Jenny ^LU (2019) In EJNMMI Research 9(1).

Abstract: Background: Block-sequential regularized expectation maximization (BSREM), commercially Q. Clear (GE Healthcare, Milwaukee, WI, USA), is a reconstruction algorithm that allows for a fully convergent iterative reconstruction leading to higher image contrast compared to conventional reconstruction algorithms, while also limiting noise. The noise penalization factor β controls the trade-off between noise level and resolution and can be adjusted by the user. The aim was to evaluate the influence of different β values for different activity time products (ATs = administered activity × acquisition time) in whole-body ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography with computed tomography (PET-CT) regarding quantitative... (More); Background: Block-sequential regularized expectation maximization (BSREM), commercially Q. Clear (GE Healthcare, Milwaukee, WI, USA), is a reconstruction algorithm that allows for a fully convergent iterative reconstruction leading to higher image contrast compared to conventional reconstruction algorithms, while also limiting noise. The noise penalization factor β controls the trade-off between noise level and resolution and can be adjusted by the user. The aim was to evaluate the influence of different β values for different activity time products (ATs = administered activity × acquisition time) in whole-body ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography with computed tomography (PET-CT) regarding quantitative data, interpretation, and quality assessment of the images. Twenty-five patients with known or suspected malignancies, referred for clinical ¹⁸F-FDG PET-CT examinations acquired on a silicon photomultiplier PET-CT scanner, were included. The data were reconstructed using BSREM with β values of 100–700 and ATs of 4–16 MBq/kg × min/bed (acquisition times of 1, 1.5, 2, 3, and 4 min/bed). Noise level, lesion SUV_max, and lesion SUV_peak were calculated. Image quality and lesion detectability were assessed by four nuclear medicine physicians for acquisition times of 1.0 and 1.5 min/bed position. Results: The noise level decreased with increasing β values and ATs. Lesion SUV_max varied considerably between different β values and ATs, whereas SUV_peak was more stable. For an AT of 6 (in our case 1.5 min/bed), the best image quality was obtained with a β of 600 and the best lesion detectability with a β of 500. AT of 4 generated poor-quality images and false positive uptakes due to noise. Conclusions: For oncologic whole-body ¹⁸F-FDG examinations on a SiPM-based PET-CT, we propose using an AT of 6 (i.e., 4 MBq/kg and 1.5 min/bed) reconstructed with BSREM using a β value of 500–600 in order to ensure image quality and lesion detection rate as well as a high patient throughput. We do not recommend using AT < 6 since the risk of false positive uptakes due to noise increases.
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Please use this url to cite or link to this publication: https://lup.lub.lu.se/record/6213744a-1b1e-49b7-82da-6e0438a998ac

author

Trägårdh, Elin ^LU ; Minarik, David ^LU ; Almquist, Helén ^LU ; Bitzén, Ulrika ^LU ; Garpered, Sabine ^LU ; Hvittfelt, Erland ^LU

; Olsson, Berit ^LU and Oddstig, Jenny ^LU

organization

publishing date

2019-07-24

type

Contribution to journal

publication status

published

subject

Radiology, Nuclear Medicine and Medical Imaging

keywords

Block-sequential regularized expectation maximization, FDG, Image reconstruction, PET-CT, Q. Clear

in

EJNMMI Research

volume

9

issue

1

article number

64

publisher

BioMed Central (BMC)

external identifiers

scopus:85069740078

ISSN

2191-219X

DOI

10.1186/s13550-019-0535-4

language

English

LU publication?

yes

id

6213744a-1b1e-49b7-82da-6e0438a998ac

date added to LUP

2019-08-02 08:39:44

date last changed

2022-05-11 20:27:14

@article{6213744a-1b1e-49b7-82da-6e0438a998ac,
  abstract     = {{<p>Background: Block-sequential regularized expectation maximization (BSREM), commercially Q. Clear (GE Healthcare, Milwaukee, WI, USA), is a reconstruction algorithm that allows for a fully convergent iterative reconstruction leading to higher image contrast compared to conventional reconstruction algorithms, while also limiting noise. The noise penalization factor β controls the trade-off between noise level and resolution and can be adjusted by the user. The aim was to evaluate the influence of different β values for different activity time products (ATs = administered activity × acquisition time) in whole-body <sup>18</sup>F-fluorodeoxyglucose (FDG) positron emission tomography with computed tomography (PET-CT) regarding quantitative data, interpretation, and quality assessment of the images. Twenty-five patients with known or suspected malignancies, referred for clinical <sup>18</sup>F-FDG PET-CT examinations acquired on a silicon photomultiplier PET-CT scanner, were included. The data were reconstructed using BSREM with β values of 100–700 and ATs of 4–16 MBq/kg × min/bed (acquisition times of 1, 1.5, 2, 3, and 4 min/bed). Noise level, lesion SUV<sub>max</sub>, and lesion SUV<sub>peak</sub> were calculated. Image quality and lesion detectability were assessed by four nuclear medicine physicians for acquisition times of 1.0 and 1.5 min/bed position. Results: The noise level decreased with increasing β values and ATs. Lesion SUV<sub>max</sub> varied considerably between different β values and ATs, whereas SUV<sub>peak</sub> was more stable. For an AT of 6 (in our case 1.5 min/bed), the best image quality was obtained with a β of 600 and the best lesion detectability with a β of 500. AT of 4 generated poor-quality images and false positive uptakes due to noise. Conclusions: For oncologic whole-body <sup>18</sup>F-FDG examinations on a SiPM-based PET-CT, we propose using an AT of 6 (i.e., 4 MBq/kg and 1.5 min/bed) reconstructed with BSREM using a β value of 500–600 in order to ensure image quality and lesion detection rate as well as a high patient throughput. We do not recommend using AT &lt; 6 since the risk of false positive uptakes due to noise increases.</p>}},
  author       = {{Trägårdh, Elin and Minarik, David and Almquist, Helén and Bitzén, Ulrika and Garpered, Sabine and Hvittfelt, Erland and Olsson, Berit and Oddstig, Jenny}},
  issn         = {{2191-219X}},
  keywords     = {{Block-sequential regularized expectation maximization; FDG; Image reconstruction; PET-CT; Q. Clear}},
  language     = {{eng}},
  month        = {{07}},
  number       = {{1}},
  publisher    = {{BioMed Central (BMC)}},
  series       = {{EJNMMI Research}},
  title        = {{Impact of acquisition time and penalizing factor in a block-sequential regularized expectation maximization reconstruction algorithm on a Si-photomultiplier-based PET-CT system for <sup>18</sup>F-FDG}},
  url          = {{http://dx.doi.org/10.1186/s13550-019-0535-4}},
  doi          = {{10.1186/s13550-019-0535-4}},
  volume       = {{9}},
  year         = {{2019}},
}

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Impact of acquisition time and penalizing factor in a block-sequential regularized expectation maximization reconstruction algorithm on a Si-photomultiplier-based PET-CT system for ¹⁸F-FDG