Noise and Edge Artifacts in Maximum-Likelihood Reconstructions for Emission Tomography

Donald L. Snyder, Michael I. Miller, Lewis J. Thomas, David G. Politte

Research output: Contribution to journalArticlepeer-review

327 Scopus citations


Images produced in emission tomography with the expectation-maximization algorithm have been observed to become more noisy and to have large distortions near edges as iterations proceed and the images converge towards the maximum-likelihood estimate. It is our conclusion that these artifacts are fundamental to reconstructions based on maximum-likelihood estimation as it has been applied usually; they are not due to the use of the expectation-maximization algorithm, which is but one numerical approach for finding the maxi-mum-likelihood estimate. In this paper, we develop a mathematical approach for suppressing both the noise and edge artifacts by modifying the maximum-likelihood approach to include constraints which the estimate must satisfy.

Original languageEnglish
Pages (from-to)228-238
Number of pages11
JournalIEEE Transactions on Medical Imaging
Issue number3
StatePublished - Sep 1987


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