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Bias evaluation and reduction in 3D OP-OSEM reconstruction in dynamic equilibrium PET studies with (11)C-labeled for binding potential analysis

Iterative image reconstruction is widely used in positron emission tomography. However, it is known to contribute to quantitation bias and is particularly pronounced during dynamic studies with (11)C-labeled radiotracers where count rates become low towards the end of the acquisition. As the strengt...

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Autores principales: Brambilla, Cláudia Régio, Scheins, Jürgen, Issa, Ahlam, Tellmann, Lutz, Herzog, Hans, Rota Kops, Elena, Shah, N. Jon, Neuner, Irene, Lerche, Christoph W.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7822533/
https://www.ncbi.nlm.nih.gov/pubmed/33481896
http://dx.doi.org/10.1371/journal.pone.0245580
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author Brambilla, Cláudia Régio
Scheins, Jürgen
Issa, Ahlam
Tellmann, Lutz
Herzog, Hans
Rota Kops, Elena
Shah, N. Jon
Neuner, Irene
Lerche, Christoph W.
author_facet Brambilla, Cláudia Régio
Scheins, Jürgen
Issa, Ahlam
Tellmann, Lutz
Herzog, Hans
Rota Kops, Elena
Shah, N. Jon
Neuner, Irene
Lerche, Christoph W.
author_sort Brambilla, Cláudia Régio
collection PubMed
description Iterative image reconstruction is widely used in positron emission tomography. However, it is known to contribute to quantitation bias and is particularly pronounced during dynamic studies with (11)C-labeled radiotracers where count rates become low towards the end of the acquisition. As the strength of the quantitation bias depends on the counts in the reconstructed frame, it can differ from frame to frame of the acquisition. This is especially relevant in the case of neuro-receptor studies with simultaneous PET/MR when a bolus-infusion protocol is applied to allow the comparison of pre- and post-task effects. Here, count dependent changes in quantitation bias may interfere with task changes. We evaluated the impact of different framing schemes on quantitation bias and its propagation into binding potential (BP) using a phantom decay study with (11)C and 3D OP-OSEM. Further, we propose a framing scheme that keeps the true counts per frame constant over the acquisition time as constant framing schemes and conventional increasing framing schemes are unlikely to achieve stable bias values during the acquisition time range. For a constant framing scheme with 5 minutes frames, the BP bias was 7.13±2.01% (10.8% to 3.8%) compared to 5.63±2.85% (7.8% to 4.0%) for conventional increasing framing schemes. Using the proposed constant true counts framing scheme, a stabilization of the BP bias was achieved at 2.56±3.92% (3.5% to 1.7%). The change in BP bias was further studied by evaluating the linear slope during the acquisition time interval. The lowest slope values were observed in the constant true counts framing scheme. The constant true counts framing scheme was effective for BP bias stabilization at relevant activity and time ranges. The mean BP bias under these conditions was 2.56±3.92%, which represents the lower limit for the detection of changes in BP during equilibrium and is especially important in the case of cognitive tasks where the expected changes are low.
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spelling pubmed-78225332021-02-01 Bias evaluation and reduction in 3D OP-OSEM reconstruction in dynamic equilibrium PET studies with (11)C-labeled for binding potential analysis Brambilla, Cláudia Régio Scheins, Jürgen Issa, Ahlam Tellmann, Lutz Herzog, Hans Rota Kops, Elena Shah, N. Jon Neuner, Irene Lerche, Christoph W. PLoS One Research Article Iterative image reconstruction is widely used in positron emission tomography. However, it is known to contribute to quantitation bias and is particularly pronounced during dynamic studies with (11)C-labeled radiotracers where count rates become low towards the end of the acquisition. As the strength of the quantitation bias depends on the counts in the reconstructed frame, it can differ from frame to frame of the acquisition. This is especially relevant in the case of neuro-receptor studies with simultaneous PET/MR when a bolus-infusion protocol is applied to allow the comparison of pre- and post-task effects. Here, count dependent changes in quantitation bias may interfere with task changes. We evaluated the impact of different framing schemes on quantitation bias and its propagation into binding potential (BP) using a phantom decay study with (11)C and 3D OP-OSEM. Further, we propose a framing scheme that keeps the true counts per frame constant over the acquisition time as constant framing schemes and conventional increasing framing schemes are unlikely to achieve stable bias values during the acquisition time range. For a constant framing scheme with 5 minutes frames, the BP bias was 7.13±2.01% (10.8% to 3.8%) compared to 5.63±2.85% (7.8% to 4.0%) for conventional increasing framing schemes. Using the proposed constant true counts framing scheme, a stabilization of the BP bias was achieved at 2.56±3.92% (3.5% to 1.7%). The change in BP bias was further studied by evaluating the linear slope during the acquisition time interval. The lowest slope values were observed in the constant true counts framing scheme. The constant true counts framing scheme was effective for BP bias stabilization at relevant activity and time ranges. The mean BP bias under these conditions was 2.56±3.92%, which represents the lower limit for the detection of changes in BP during equilibrium and is especially important in the case of cognitive tasks where the expected changes are low. Public Library of Science 2021-01-22 /pmc/articles/PMC7822533/ /pubmed/33481896 http://dx.doi.org/10.1371/journal.pone.0245580 Text en © 2021 Brambilla et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Brambilla, Cláudia Régio
Scheins, Jürgen
Issa, Ahlam
Tellmann, Lutz
Herzog, Hans
Rota Kops, Elena
Shah, N. Jon
Neuner, Irene
Lerche, Christoph W.
Bias evaluation and reduction in 3D OP-OSEM reconstruction in dynamic equilibrium PET studies with (11)C-labeled for binding potential analysis
title Bias evaluation and reduction in 3D OP-OSEM reconstruction in dynamic equilibrium PET studies with (11)C-labeled for binding potential analysis
title_full Bias evaluation and reduction in 3D OP-OSEM reconstruction in dynamic equilibrium PET studies with (11)C-labeled for binding potential analysis
title_fullStr Bias evaluation and reduction in 3D OP-OSEM reconstruction in dynamic equilibrium PET studies with (11)C-labeled for binding potential analysis
title_full_unstemmed Bias evaluation and reduction in 3D OP-OSEM reconstruction in dynamic equilibrium PET studies with (11)C-labeled for binding potential analysis
title_short Bias evaluation and reduction in 3D OP-OSEM reconstruction in dynamic equilibrium PET studies with (11)C-labeled for binding potential analysis
title_sort bias evaluation and reduction in 3d op-osem reconstruction in dynamic equilibrium pet studies with (11)c-labeled for binding potential analysis
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7822533/
https://www.ncbi.nlm.nih.gov/pubmed/33481896
http://dx.doi.org/10.1371/journal.pone.0245580
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