RT Journal Article
SR Electronic
T1 Truncation artifacts in whole-body PET/MR - Compensation and evaluation
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 659
OP 659
VO 54
IS supplement 2
A1 Schramm, Georg
A1 Langner, Jens
A1 Hofheinz, Frank
A1 Petr, Jan
A1 Beuthien-Baumann, Bettina
A1 Platzek, Ivan
A1 Kotzerke, Jorg
A1 Steinbach, Jörg
A1 van den Hoff, Jörg
YR 2013
UL http://jnm.snmjournals.org/content/54/supplement_2/659.abstract
AB 659 Objectives In whole-body PET/MR examinations the reduced transaxial FOV of the MR (40cm), in comparison to that of the PET scanner (60cm), leads to truncation artifacts (TAs) in the MR-based attenuation map (MRMap). We investigated the quantitative influence of TAs on the reconstructed PET image volumes and developed a new method for truncation compensation (TC). Methods 20 patient investigations with arms down (FDG, BMI 16-38) from a Philips Ingenuity PET/MR were reconstructed using different techniques for TC: (a) no TC (PET-noTC), (b) vendor-provided TC (PET-TC1), (c) newly developed TC (PET-TC2) based on automatic 3D segmentation of PET-noTC. SUVmax/mean deviations of tracer accumulations at different locations (e.g. heart, bladder, kidneys, arms etc.) were analysed. Moreover, a correlation analysis between all voxels in the trunk and truncated arms was performed. Results Residual artifacts in the truncation compensated MRMaps were found in 11 (TC1) and 3 (TC2) out of 20 cases. Average SUVmax differences between PET-noTC and PET-TC2 were: -3.3% (bladder), -3.6% (kidney), -3.3% (heart), -3.4% (abdomen), -38.9% (arms). The correlation analysis showed average SUV underestimations of -10% to -1% and -68% to -12% depending on patients' BMI for all voxels in the trunk and truncated arms, respectively. Conclusions In whole-body PET/MR imaging with arms down, TAs in the MRMap lead to an average SUV underestimation inside the trunk of ca. -3% . In the truncated areas and their immediate vicinity substantial SUV underestimation (-10 to -70%) can be expected. Compensation of TAs based on PET-noTC is straightforward, improves quantification accuracy distinctly and has turned out to be well suited for clinical routine.