The influence of filtered back-projection and iterative reconstruction on partial volume correction in PET.
OBJECTIVE
We assess the influence of the reconstruction algorithms [OS-EM for the iterative one vs. a filtered back-projection in Fourier space (DiFT)] on partial volume correction in PET employing a fully 3D 3-compartment MR based PV-correction algorithm. The gray matter voxels in the PET image -- after removal of the white matter and cerebrospinal fluid contribution -- are corrected voxel-by-voxel using the image resolution.


METHODS
Phantom measurements and one healthy human brain FDG study were carried out. For the OSEM reconstruction, a combination of iteration steps and subset numbers (It/Sub) was used, whereby in case of no-convergence the image resolution had to be fitted. The RESULTS from the DiFT reconstruction were equivalent to those obtained from the OSEM reconstruction with 10/32 combination for objects with widespread activity concentration. For the sphere phantom, the mean recovery based on the actual values achieved 99.2% +/- 1.8 for all spheres and all reconstruction modes and It/sub combinations (except for 2/8). In case of the Hoffman 3D brain phantom the mean recovery of the cortical regions was 101% +/- 1.2 (the increase based on the uncorrected values: 35.5% +/- 1.5), while the subcortical regions reached a mean recovery of 80% with an increase of 43.9% +/- 2.5. For the human data, an increase of the metabolized values of several cortical regions ranged between 42% and 48% independent from the reconstruction mode.


CONCLUSIONS
Our data show that the 3-compartment fully 3-D MR based PV-correction is sensitive to the choice of reconstruction algorithms and to the parameter choice. They indicate that despite improved spatial resolution, the use of the iterative reconstruction algorithm for PV-correction results in similar recovery factors when compared to a correction using DiFT reconstruction, insofar the image resolution values are fitted at the It/Sub combinations.
Rota Kops
E
E
Institute of Medicine, Forschungszentrum Jülich, 52425 Jülich, Germany. e.rota.kops@fz-juelich.de
Krause
B J
BJ
D000465:Algorithms; D001921:Brain / Q000000981:diagnostic imaging; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D009369:Neoplasms / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000379:methods*
D019788:Fluorodeoxyglucose F18