Positron emission tomography (PET) attenuation correction artefacts in PET/CT and PET/MRI
C Buchbender1, V Hartung-Knemeyer, M Forsting
1Department of Diagnostic and Interventional Radiology, Medical Faculty, University of Dusseldorf, Dusseldorf, Germany. Christian.buchbender@med.uni-duesseldorf.de
Objective:
To compare the effect of implanted medical materials on (18)F-fludeoxyglucose ((18)F-FDG) positron emission tomography (PET)/MRI using a Dixon-based segmentation method for MRI-based attenuation correction (MRAC), PET/CT and CT-based attenuation-corrected PET (PETCTAC).
Methods:
12 patients (8 males and 4 females; age 58±11 years) with implanted medical materials prospectively underwent whole-body (18)F-FDG PET/CT and PET/MRI. CT, MRI and MRAC maps as well as PETCTAC and PETMRAC images were reviewed for the presence of artefacts. Their morphology and effect on the estimation of the (18)F-FDG uptake (no effect, underestimation, overestimation compared with non-corrected images) were compared. In PETMRAC images, a volume of interest was drawn in the area of the artefact and in a reference site (contralateral body part); the mean and maximum standardised uptake values (SUVmean; SUVmax) were measured.
Results:
Of 27 implanted materials (20 dental fillings, 3 injection ports, 3 hip prostheses and 1 sternal cerclage), 27 (100%) caused artefacts in CT, 19 (70%) in T1 weighted MRI and 17 (63%) in MRAC maps. 20 (74%) caused a visual overestimation of the (18)F-FDG uptake in PETCTAC, 2 (7%) caused an underestimation and 5 (19%) had no effect. In PETMRAC, 19 (70%) caused spherical extinctions and 8 (30%) had no effect. Mean values for SUVmean and SUVmax were significantly decreased in artefact-harbouring sites (p<0.001).
Conclusion:
Contrary to PET attenuation correction artefacts in PET/CT, which often show an overestimation of the (18)F-FDG uptake, MRAC artefacts owing to implanted medical materials in most cases cause an underestimation.
Advances In Knowledge:
Being aware of the morphology of artefacts owing to implanted medical materials avoids interpretation errors when reading PET/MRI.
Insights
Implanted medical materials cause artifacts in PET/CT and PET/MRI. Unlike PET/CT, MRI-based attenuation correction (MRAC) artifacts typically underestimate (18)F-FDG uptake, aiding interpretation.
Area of Science:
- Medical Imaging
- Radiochemistry
- Biomedical Engineering
Background:
- Implanted medical materials can cause artifacts in positron emission tomography (PET) imaging.
- Accurate attenuation correction is crucial for quantitative PET analysis.
- MRI-based attenuation correction (MRAC) offers an alternative to CT-based methods.
Purpose of the Study:
- To compare the impact of implanted medical materials on (18)F-FDG PET/MRI using MRAC versus PET/CT.
- To characterize the morphology and effect of artifacts on (18)F-FDG uptake quantification.
Main Methods:
- 12 patients with implanted materials underwent whole-body (18)F-FDG PET/CT and PET/MRI.
- CT, MRI, and MRAC images were analyzed for artifacts.
- Artifacts' effects on (18)F-FDG uptake (underestimation/overestimation) were compared between PET/CT and PET/MRI.
Main Results:
- All implanted materials caused CT artifacts; 70% caused MRI artifacts and 63% caused MRAC artifacts.
- PET/CT showed overestimation of (18)F-FDG uptake in 74% of cases.
- PET/MRI with MRAC resulted in underestimation of (18)F-FDG uptake in 70% of cases.
Conclusions:
- MRI-based attenuation correction (MRAC) artifacts from implanted materials tend to underestimate (18)F-FDG uptake, unlike PET/CT artifacts.
- Awareness of MRAC artifact morphology is essential to prevent misinterpretation in PET/MRI.
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