RT Journal Article
SR Electronic
T1 Motion-corrected EM (MC-EM) reconstruction of gated PET-MRI data
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 591
OP 591
VO 50
IS supplement 2
A1 Bastien Guerin
A1 Georges El Fakhri
YR 2009
UL http://jnm.snmjournals.org/content/50/supplement_2/591.abstract
AB 591 Objectives We present a novel EM reconstruction of gated PET data that models motion estimated by MRI yielding one single motion-free reconstructed image containing all detected counts. We assess its accuracy in simulations of a breathing XCAT phantom. Methods We propose a MC-EM algorithm to reconstruct simultaneously all frames of a gated acquisition into a single image while correcting for motion between frames. MC-EM uses the motion field (rigid and non-rigid) that can be estimated by MRI in simultaneous PET-MRI acquisitions. Modeling motion in the system matrix allows preserving the Poisson nature of the data. We compared the accuracy of MC-EM to that of the un-gated approach (NG) and to that of a gated approach in which frames are reconstructed independently (GFRI). We modeled Poisson noise and non-uniform attenuation in a breathing XCAT phantom and assessed myocardial wall thickness, relative noise (standard deviation to mean ratio in a uniform background) and apical activity estimation in the reference image and in images reconstructed with MC-EM, NG and GFRI methods . Results Estimation of myocardial wall thickness (reference=1.54 cm) was 2.47 (NG); 1.77 (GFRI) and 1.56 cm (MC-LEM). Relative noise was 29% (NG), 57% (GFRI) and 20% (MC-EM). Error in apical activity estimation was 46% (NG); 9% (GFRI) and 8% (MC-EM). Conclusions Incorporating motion in the system matrix of an EM reconstruction algorithm improves size and activity estimations while maximizing SNR by reconstructing all detected counts into a single image. This strategy preserves the Poisson nature of the data and is therefore more optimal than other de-blurring strategies operating on reconstructed images. Research Support R01-EB5876, R21-CA134812