Investigation of the halo-artifact in 68Ga-PSMA-11-PET/MRI.
Combined positron emission tomography (PET) and magnetic resonance imaging (MRI) targeting the prostate-specific membrane antigen (PSMA) with a 68Ga-labelled PSMA-analog (68Ga-PSMA-11) is discussed as a promising diagnostic method for patients with suspicion or history of prostate cancer. One potent...
| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Public Library of Science (PLoS)
2017-01-01
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| Series: | PLoS ONE |
| Online Access: | http://europepmc.org/articles/PMC5560715?pdf=render |
| _version_ | 1819070643239387136 |
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| author | Thorsten Heußer Philipp Mann Christopher M Rank Martin Schäfer Antonia Dimitrakopoulou-Strauss Heinz-Peter Schlemmer Boris A Hadaschik Klaus Kopka Peter Bachert Marc Kachelrieß Martin T Freitag |
| author_facet | Thorsten Heußer Philipp Mann Christopher M Rank Martin Schäfer Antonia Dimitrakopoulou-Strauss Heinz-Peter Schlemmer Boris A Hadaschik Klaus Kopka Peter Bachert Marc Kachelrieß Martin T Freitag |
| author_sort | Thorsten Heußer |
| collection | DOAJ |
| description | Combined positron emission tomography (PET) and magnetic resonance imaging (MRI) targeting the prostate-specific membrane antigen (PSMA) with a 68Ga-labelled PSMA-analog (68Ga-PSMA-11) is discussed as a promising diagnostic method for patients with suspicion or history of prostate cancer. One potential drawback of this method are severe photopenic (halo-) artifacts surrounding the bladder and the kidneys in the scatter-corrected PET images, which have been reported to occur frequently in clinical practice. The goal of this work was to investigate the occurrence and impact of these artifacts and, secondly, to evaluate variants of the standard scatter correction method with regard to halo-artifact suppression.Experiments using a dedicated pelvis phantom were conducted to investigate whether the halo-artifact is modality-, tracer-, and/or concentration-dependent. Furthermore, 31 patients with history of prostate cancer were selected from an ongoing 68Ga-PSMA-11-PET/MRI study. For each patient, PET raw data were reconstructed employing six different variants of PET scatter correction: absolute scatter scaling, relative scatter scaling, and relative scatter scaling combined with prompt gamma correction, each of which was combined with a maximum scatter fraction (MaxSF) of MaxSF = 75% or MaxSF = 40%. Evaluation of the reconstructed images with regard to halo-artifact suppression was performed both quantitatively using statistical analysis and qualitatively by two independent readers.The phantom experiments did not reveal any modality-dependency (PET/MRI vs. PET/CT) or tracer-dependency (68Ga vs. 18F-FDG). Patient- and phantom-based data indicated that halo-artifacts derive from high organ-to-background activity ratios (OBR) between bladder/kidneys and surrounding soft tissue, with a positive correlation between OBR and halo size. Comparing different variants of scatter correction, reducing the maximum scatter fraction from the default value MaxSF = 75% to MaxSF = 40% was found to efficiently suppress halo-artifacts in both phantom and patient data. In 1 of 31 patients, reducing the maximum scatter fraction provided new PET-based information changing the patient's diagnosis.Halo-artifacts are particularly observed for 68Ga-PSMA-11-PET/MRI due to 1) the biodistribution of the PSMA-11-tracer resulting in large OBRs for bladder and kidneys and 2) inaccurate scatter correction methods currently used in clinical routine, which tend to overestimate the scatter contribution. If not compensated for, 68Ga-PSMA-11 uptake pathologies may be masked by halo-artifacts leading to false-negative diagnoses. Reducing the maximum scatter fraction was found to efficiently suppress halo-artifacts. |
| first_indexed | 2024-12-21T17:09:12Z |
| format | Article |
| id | doaj.art-b6fe59af63f548df80cc6f033ae5f726 |
| institution | Directory Open Access Journal |
| issn | 1932-6203 |
| language | English |
| last_indexed | 2024-12-21T17:09:12Z |
| publishDate | 2017-01-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS ONE |
| spelling | doaj.art-b6fe59af63f548df80cc6f033ae5f7262022-12-21T18:56:27ZengPublic Library of Science (PLoS)PLoS ONE1932-62032017-01-01128e018332910.1371/journal.pone.0183329Investigation of the halo-artifact in 68Ga-PSMA-11-PET/MRI.Thorsten HeußerPhilipp MannChristopher M RankMartin SchäferAntonia Dimitrakopoulou-StraussHeinz-Peter SchlemmerBoris A HadaschikKlaus KopkaPeter BachertMarc KachelrießMartin T FreitagCombined positron emission tomography (PET) and magnetic resonance imaging (MRI) targeting the prostate-specific membrane antigen (PSMA) with a 68Ga-labelled PSMA-analog (68Ga-PSMA-11) is discussed as a promising diagnostic method for patients with suspicion or history of prostate cancer. One potential drawback of this method are severe photopenic (halo-) artifacts surrounding the bladder and the kidneys in the scatter-corrected PET images, which have been reported to occur frequently in clinical practice. The goal of this work was to investigate the occurrence and impact of these artifacts and, secondly, to evaluate variants of the standard scatter correction method with regard to halo-artifact suppression.Experiments using a dedicated pelvis phantom were conducted to investigate whether the halo-artifact is modality-, tracer-, and/or concentration-dependent. Furthermore, 31 patients with history of prostate cancer were selected from an ongoing 68Ga-PSMA-11-PET/MRI study. For each patient, PET raw data were reconstructed employing six different variants of PET scatter correction: absolute scatter scaling, relative scatter scaling, and relative scatter scaling combined with prompt gamma correction, each of which was combined with a maximum scatter fraction (MaxSF) of MaxSF = 75% or MaxSF = 40%. Evaluation of the reconstructed images with regard to halo-artifact suppression was performed both quantitatively using statistical analysis and qualitatively by two independent readers.The phantom experiments did not reveal any modality-dependency (PET/MRI vs. PET/CT) or tracer-dependency (68Ga vs. 18F-FDG). Patient- and phantom-based data indicated that halo-artifacts derive from high organ-to-background activity ratios (OBR) between bladder/kidneys and surrounding soft tissue, with a positive correlation between OBR and halo size. Comparing different variants of scatter correction, reducing the maximum scatter fraction from the default value MaxSF = 75% to MaxSF = 40% was found to efficiently suppress halo-artifacts in both phantom and patient data. In 1 of 31 patients, reducing the maximum scatter fraction provided new PET-based information changing the patient's diagnosis.Halo-artifacts are particularly observed for 68Ga-PSMA-11-PET/MRI due to 1) the biodistribution of the PSMA-11-tracer resulting in large OBRs for bladder and kidneys and 2) inaccurate scatter correction methods currently used in clinical routine, which tend to overestimate the scatter contribution. If not compensated for, 68Ga-PSMA-11 uptake pathologies may be masked by halo-artifacts leading to false-negative diagnoses. Reducing the maximum scatter fraction was found to efficiently suppress halo-artifacts.http://europepmc.org/articles/PMC5560715?pdf=render |
| spellingShingle | Thorsten Heußer Philipp Mann Christopher M Rank Martin Schäfer Antonia Dimitrakopoulou-Strauss Heinz-Peter Schlemmer Boris A Hadaschik Klaus Kopka Peter Bachert Marc Kachelrieß Martin T Freitag Investigation of the halo-artifact in 68Ga-PSMA-11-PET/MRI. PLoS ONE |
| title | Investigation of the halo-artifact in 68Ga-PSMA-11-PET/MRI. |
| title_full | Investigation of the halo-artifact in 68Ga-PSMA-11-PET/MRI. |
| title_fullStr | Investigation of the halo-artifact in 68Ga-PSMA-11-PET/MRI. |
| title_full_unstemmed | Investigation of the halo-artifact in 68Ga-PSMA-11-PET/MRI. |
| title_short | Investigation of the halo-artifact in 68Ga-PSMA-11-PET/MRI. |
| title_sort | investigation of the halo artifact in 68ga psma 11 pet mri |
| url | http://europepmc.org/articles/PMC5560715?pdf=render |
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