Cited by 20Medical Imaging Techniques and ApplicationsRadiation Dose and ImagingCardiac Imaging and Diagnostics

Impact of penalizing factor in a block-sequential regularized expectation maximization reconstruction algorithm for 18F-fluorocholine PET-CT regarding image quality and interpretation

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Bjöersdorff, Mimmi, Oddstig, Jenny, Karindotter-Borgendahl, Nina, Almquist, Helén, Zackrisson, Sophia, Minarik, David, Trägårdh, Elin·2019·EJNMMI Physics

Abstract

Recently, the block-sequential regularized expectation maximization (BSREM) reconstruction algorithm was commercially introduced (Q.Clear, GE Healthcare, Milwaukee, WI, USA). However, the combination of noise-penalizing factor (β), acquisition time, and administered activity for optimal image quality has not been established for 18 F-fluorocholine (FCH). The aim was to compare image quality and diagnostic performance of different reconstruction protocols for patients with prostate cancer being examined with 18 F-FCH on a silicon photomultiplier-based PET-CT. Thirteen patients were included, injected with 4 MBq/kg, and images were acquired after 1 h. Images were reconstructed with frame durations of 1.0, 1.5, and 2.0 min using β of 150, 200, 300, 400, 500, and 550. An ordered subset expectation maximization (OSEM) reconstruction with a frame duration of 2.0 min was used for comparison. Images were quantitatively analyzed regarding standardized uptake values (SUV) in metastatic lymph nodes, local background, and muscle to obtain contrast-to-noise ratios (CNR) as well as the noise level in muscle. Images were analyzed regarding image quality and number of metastatic lymph nodes by two nuclear medicine physicians. The highest median CNR was found for BSREM with a β of 300 and a frame duration of 2.0 min. The OSEM reconstruction had the lowest median CNR. Both the noise level and lesion SUV max decreased with increasing β. For a frame duration of 1.5 min, the median quality score was highest for β 400-500, and for a frame duration of 2.0 min the score was highest for β 300-500. There was no statistically significant difference in the number of suspected lymph node metastases between the different image series for one of the physicians, and for the other physician the number of lymph nodes differed only for one combination of image series. To achieve acceptable image quality at 4 MBq/kg 18 F-FCH, we propose using a β of 400-550 with a frame duration of 1.5 min. The lower β should be used if a high CNR is desired and the higher if a low noise level is important.

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  • Several studies on subjective image quality in whole-body [18F]FDG-PET with PL reconstruction found that image quality was highest at beta values of 450 (to 600) despite lower lesion contrast recovery or image sharpness at these beta values compared to lower values.

    “Several studies on subjective image quality in whole-body [18F]FDG-PET with PL reconstruction found that image quality was highest at beta values of 450 (to 600) despite lower lesion CR or “image sharpness” at these beta values compared to lower values [41,108,112,175,179].”

    From Influences on PET Quantification and Interpretation (2022) · cites this paper as [175]

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  • In a small sample of 13 patients undergoing [18F]fluorocholine PET/CT for prostate cancer staging, PL with different beta values showed a comparable number of positive lymph nodes to that revealed by OSEM with PSF and TOF.

    “In contrast, in a small sample of 13 patients undergoing [18F]fluorocholine PET/CT for prostate cancer staging, PL with different beta values showed a comparable number of positive lymph nodes to that revealed by OSEM with PSF and TOF [175].”

    From Influences on PET Quantification and Interpretation (2022) · cites this paper as [175]

    Methods (Clinical data and Imaging data) report 13 patients with high-risk prostate cancer and compare reconstructions with different β values against OSEM with point-spread function and time-of-flight. Results (Qualitative analysis) find largely comparable numbers of suspected metastatic lymph nodes, but Figure 6 says that assessment covered ten patients, not all 13; the nodes were suspected rather than confirmed positive. (LLM, conf=0.88)

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Authors
Bjöersdorff, M., Oddstig, J., Karindotter-Borgendahl, N., Almquist, H., Zackrisson, S., Minarik, D., & Trägårdh, E.
Affiliations
Lund University (SE)
Corresponding author
Bjöersdorff, Mimmi
Venue
EJNMMI Physics
Published
2019-03-21
Volume
6
Issue
1
Pages
5-5
ISSN
2197-7364 (ISSN-L)
OpenAlex
W2936746547
Cited by
20
References
18
Citations by year
2025: 2 · 2024: 3 · 2023: 3 · 2022: 6 · 2021: 2 · 2020: 4
FWCI
1.98
Type
journal article
Language
en
Open access
Locations
  • EJNMMI Physics (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • Lund University Publications (Lund University) (submittedVersion)
Funders
Knut och Alice Wallenbergs Stiftelse (-)
Topics
  • Health Sciences › Medicine › Radiology, Nuclear Medicine and Imaging › Medical Imaging Techniques and Applications
  • Health Sciences › Medicine › Radiology, Nuclear Medicine and Imaging › Radiation Dose and Imaging
  • Health Sciences › Medicine › Radiology, Nuclear Medicine and Imaging › Cardiac Imaging and Diagnostics
Keywords
18F-fluorocholine, BSREM, prostate cancer, lymph node metastasis detection, OSEM, frame duration, contrast-to-noise ratio, image quality, standardized uptake value, low-dose imaging

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