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Portrait of Sophia Zackrisson. Photo

Sophia Zackrisson

Research group manager, Principal investigator, Professor, MD

Portrait of Sophia Zackrisson. Photo

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

Author

  • Mimmi Bjöersdorff
  • Jenny Oddstig
  • Nina Karindotter-Borgendahl
  • Helén Almquist
  • Sophia Zackrisson
  • David Minarik
  • Elin Trägårdh

Summary, in English


Background: 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. Results: 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. Conclusions: 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.

Department/s

  • Nuclear medicine, Malmö
  • BioCARE: Biomarkers in Cancer Medicine improving Health Care, Education and Innovation
  • Clinical Physiology (Lund)
  • Radiology Diagnostics, Malmö
  • Medical Radiation Physics, Malmö
  • WCMM-Wallenberg Centre for Molecular Medicine

Publishing year

2019-12-01

Language

English

Publication/Series

EJNMMI Physics

Volume

6

Issue

1

Document type

Journal article

Publisher

Springer

Topic

  • Radiology, Nuclear Medicine and Medical Imaging

Keywords

  • F-FCH
  • Image quality
  • Oncology
  • Protocol optimization
  • Q.Clear

Status

Published

Research group

  • Nuclear medicine, Malmö
  • Radiology Diagnostics, Malmö
  • Medical Radiation Physics, Malmö

ISBN/ISSN/Other

  • ISSN: 2197-7364