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

Bjöersdorff, Mimmi LU ; Oddstig, Jenny LU ; Karindotter-Borgendahl, Nina ; Almquist, Helén LU ; Zackrisson, Sophia LU ; Minarik, David LU and Trägårdh, Elin LU (2019) In EJNMMI Physics 6(1).
Abstract


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 ... (More)


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.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
F-FCH, Image quality, Oncology, Protocol optimization, Q.Clear
in
EJNMMI Physics
volume
6
issue
1
article number
5
publisher
Springer Open
external identifiers
  • scopus:85063263780
ISSN
2197-7364
DOI
10.1186/s40658-019-0242-2
language
English
LU publication?
yes
id
8a8dc3cd-2bbd-4569-84b6-e4c11ec8b8f4
date added to LUP
2019-04-01 13:38:29
date last changed
2019-11-25 09:28:41
@article{8a8dc3cd-2bbd-4569-84b6-e4c11ec8b8f4,
  abstract     = {<p><br>
                                                         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                              <br>
                            <sup>18</sup><br>
                                                         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                              <br>
                            <sup>18</sup><br>
                                                         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                             <br>
                            <sub>max</sub><br>
                                                          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                              <br>
                            <sup>18</sup><br>
                                                         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.                         <br>
                        </p>},
  author       = {Bjöersdorff, Mimmi and Oddstig, Jenny and Karindotter-Borgendahl, Nina and Almquist, Helén and Zackrisson, Sophia and Minarik, David and Trägårdh, Elin},
  issn         = {2197-7364},
  language     = {eng},
  month        = {12},
  number       = {1},
  publisher    = {Springer Open},
  series       = {EJNMMI Physics},
  title        = {Impact of penalizing factor in a block-sequential regularized expectation maximization reconstruction algorithm for                          
                        <sup>18</sup>
                                                 F-fluorocholine PET-CT regarding image quality and interpretation},
  url          = {http://dx.doi.org/10.1186/s40658-019-0242-2},
  doi          = {10.1186/s40658-019-0242-2},
  volume       = {6},
  year         = {2019},
}