TY - JOUR
T1 - Comparison of MR-based attenuation correction and CT-based attenuation correction of whole-body PET/MR imaging
AU - Izquierdo-Garcia, David
AU - Sawiak, Stephen J.
AU - Knesaurek, Karin
AU - Narula, Jagat
AU - Fuster, Valentin
AU - Machac, Joseph
AU - Fayad, Zahi A.
N1 - Funding Information:
Acknowledgments The authors acknowledge Ash Rafique and Melissa Quispe, staff members of the Nuclear Medicine Division, and Frank Macaluso and Charles Adapoe, staff members of the Translational and Molecular Imaging Institute, for their help and support with the study. They also thank Philips for their help and for providing support for CTAC reconstruction of the PET/MR data, in particular Kevin Kilroy and Gary Muswick. They especially thank Dr. Ciprian Catana of the Athinoula A. Martinos Center for his guidance and expert review of this paper. Finally, they also thank the NIH for partial support (NIH/NHLBI R01 HL071021 and R01 HL078667; D. I.-G. and Z.A.F.).
PY - 2014/8
Y1 - 2014/8
N2 - Purpose: The objective of this study was to evaluate the performance of the built-in MR-based attenuation correction (MRAC) included in the combined whole-body Ingenuity TF PET/MR scanner and compare it to the performance of CT-based attenuation correction (CTAC) as the gold standard. Methods: Included in the study were 26 patients who underwent clinical whole-body FDG PET/CT imaging and subsequently PET/MR imaging (mean delay 100 min). Patients were separated into two groups: the alpha group (14 patients) without MR coils during PET/MR imaging and the beta group (12 patients) with MR coils present (neurovascular, spine, cardiac and torso coils). All images were coregistered to the same space (PET/MR). The two PET images from PET/MR reconstructed using MRAC and CTAC were compared by voxel-based and region-based methods (with ten regions of interest, ROIs). Lesions were also compared by an experienced clinician. Results: Body mass index and lung density showed significant differences between the alpha and beta groups. Right and left lung densities were also significantly different within each group. The percentage differences in uptake values using MRAC in relation to those using CTAC were greater in the beta group than in the alpha group (alpha group -0.2 ± 33.6 %, R 2=0.98, p<0.001; beta group 10.31 ± 69.86 %, R 2=0.97, p<0.001). Conclusion: In comparison to CTAC, MRAC led to underestimation of the PET values by less than 10 % on average, although some ROIs and lesions did differ by more (including the spine, lung and heart). The beta group (imaged with coils present) showed increased overall PET quantification as well as increased variability compared to the alpha group (imaged without coils). PET data reconstructed with MRAC and CTAC showed some differences, mostly in relation to air pockets, metallic implants and attenuation differences in large bone areas (such as the pelvis and spine) due to the segmentation limitation of the MRAC method.
AB - Purpose: The objective of this study was to evaluate the performance of the built-in MR-based attenuation correction (MRAC) included in the combined whole-body Ingenuity TF PET/MR scanner and compare it to the performance of CT-based attenuation correction (CTAC) as the gold standard. Methods: Included in the study were 26 patients who underwent clinical whole-body FDG PET/CT imaging and subsequently PET/MR imaging (mean delay 100 min). Patients were separated into two groups: the alpha group (14 patients) without MR coils during PET/MR imaging and the beta group (12 patients) with MR coils present (neurovascular, spine, cardiac and torso coils). All images were coregistered to the same space (PET/MR). The two PET images from PET/MR reconstructed using MRAC and CTAC were compared by voxel-based and region-based methods (with ten regions of interest, ROIs). Lesions were also compared by an experienced clinician. Results: Body mass index and lung density showed significant differences between the alpha and beta groups. Right and left lung densities were also significantly different within each group. The percentage differences in uptake values using MRAC in relation to those using CTAC were greater in the beta group than in the alpha group (alpha group -0.2 ± 33.6 %, R 2=0.98, p<0.001; beta group 10.31 ± 69.86 %, R 2=0.97, p<0.001). Conclusion: In comparison to CTAC, MRAC led to underestimation of the PET values by less than 10 % on average, although some ROIs and lesions did differ by more (including the spine, lung and heart). The beta group (imaged with coils present) showed increased overall PET quantification as well as increased variability compared to the alpha group (imaged without coils). PET data reconstructed with MRAC and CTAC showed some differences, mostly in relation to air pockets, metallic implants and attenuation differences in large bone areas (such as the pelvis and spine) due to the segmentation limitation of the MRAC method.
KW - Attenuation correction
KW - CTAC
KW - MRAC
KW - PET/MR
UR - http://www.scopus.com/inward/record.url?scp=84905563653&partnerID=8YFLogxK
U2 - 10.1007/s00259-014-2751-5
DO - 10.1007/s00259-014-2751-5
M3 - Article
C2 - 24652234
AN - SCOPUS:84905563653
SN - 1619-7070
VL - 41
SP - 1574
EP - 1584
JO - European Journal of Nuclear Medicine and Molecular Imaging
JF - European Journal of Nuclear Medicine and Molecular Imaging
IS - 8
ER -