A simulation of emission and transmission noise propagation in cardiac SPECT imaging with nonuniform attenuation correction.

TitleA simulation of emission and transmission noise propagation in cardiac SPECT imaging with nonuniform attenuation correction.
Publication TypeJournal Article
Year of Publication1994
AuthorsTung CH, Gullberg GT
JournalMed Phys
Volume21
Issue10
Pagination1565-76
Date Published1994 Oct
ISSN0094-2405
KeywordsAlgorithms, Computer Simulation, Heart, Humans, Models, Anatomic, Models, Theoretical, Probability, Tomography, Emission-Computed, Single-Photon
Abstract

Transmission computed tomography provides information needed for nonuniform attenuation correction of cardiac single photon emission computed tomography (SPECT). Nonuniform attenuation correction is accomplished using an iterative ML-EM algorithm and a projection-backprojection operation that incorporates attenuation factors measured from the reconstructed transmission map. The precision and accuracy of the attenuation corrected emission reconstruction is a function of emission and transmission statistics. This paper presents an error propagation analysis that uses a mathematical cardiac chest phantom to simulate various combinations of total emission counts C and transmission flux I0 under ideal imaging conditions (without geometric response distortion and without scatter). The spatial average, spatial variance, and accuracy measures for a 4 x 4 pixel region in the heart are tabulated after 30 iterations of the ML-EM algorithm. The confidence intervals for these measures were determined from 1000 realizations of reconstructions from projections randomly generated with the same transmission and emission statistics. It can be shown empirically from the simulation results that the spatial %rms uncertainty for the simulated cardiac region has a simple expression: %rms2 = K1/C+K2/I0(2)+B2 where K1 and K2 are least-square estimates based on the simulation results, and B is the measured spatial %rms uncertainty for the simulation at infinite statistics. For a transmission incident flux of 1500 events per projection bin of 0.712 cm and typical clinical emission events totaling 1 x 10(5), the spatial %rms uncertainty is approximately 14%. At clinical transmission and emission statistics, the statistical noise in the simulated attenuation-corrected reconstructions are dominated by the emission statistics.

DOI10.1118/1.597266
Alternate JournalMed Phys
PubMed ID7869988
Grant ListR01 HL 39792 / HL / NHLBI NIH HHS / United States
Related Institute: 
Molecular Imaging Innovations Institute (MI3)

Weill Cornell Medicine
Department of Radiology
525 East 68th Street New York, NY 10065