Comparison between ML-EM and WLS-CG algorithms for SPECT image reconstruction

Journal Article · Sun Dec 01 04:00:00 EST 1991 · IEEE Transactions on Nuclear Science (Institute of Electrical and Electronics Engineers); (United States)

DOI:https://doi.org/10.1109/23.124174· OSTI ID:5745622

Tsui, B M.W.; Zhao, X D; Frey, E C ^[1]; Gullberg, G T ^[2]

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1. Dept. of Radiology, Univ. of North Carolina, Chapel Hill, NC (US)
2. Utah Univ., Salt Lake City, UT (United States). Dept. of Radiology

This paper reports on the properties of two iterative reconstruction algorithms, namely, the maximum likelihood with expectation maximization (ML-EM) and the weighted least squares with conjugate gradient (WLS-CG) algorithms, for use in compensation for attenuation and detector response in cardiac SPECT imaging. A realistic phantom, derived from a patient X-ray CT study to simulate {sup 201}T1 SPECT data, was used in the investigation. Both algorithms are effective in compensating for the nonuniform attenuation distribution in the thorax region and the spatially variant detector response function of the imaging system. At low iteration numbers, the addition of detector response compensation provides improvement in both spatial resolution and image noise when compared with attenuation compensation alone. However, at higher iteration numbers, there is a more rapid increase in image noise when detector response compensation is included, and the increase is more dramatic for the WLS-CG algorithm. In general, the convergence rate of the WLS-CG algorithm is about ten times that of the ML-EM algorithm. Also, the WLS-CG exhibits a faster increase in image noise at large iteration numbers than the ML-EM algorithm. This study is valuable in the search for useful and practical reconstruction methods for improved clinical cardiac SPECT imaging.

• OSTI ID: 5745622
• Journal Information: IEEE Transactions on Nuclear Science (Institute of Electrical and Electronics Engineers); (United States), Journal Name: IEEE Transactions on Nuclear Science (Institute of Electrical and Electronics Engineers); (United States) Vol. 38:6; ISSN 0018-9499; ISSN IETNA
• Country of Publication: United States
• Language: English

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