Activity and Attenuation Reconstruction for Positron Emission Tomography Using Emission Data Only Via Maximum Likelihood and Iterative Data Refinement

Crepaldi, F.; Pierro, Alvaro R. De

doi:10.1109/tns.2006.889168

Cited by 17 publications

(9 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For the simultaneous activity and attenuation reconstruction, we used the EM_AA algorithm described in Furuie et al 3,4 , which is based on expectation-maximization of likelihood. We assumed that it is possible to identify a region with known material and known attenuation coefficients, such as water or blood.…”

Section: Methodsmentioning

confidence: 99%

Simultaneous activity and attenuation reconstruction in PET: applying partially known attenuation

Furuie

2009

SPIE Proceedings

View full text Add to dashboard Cite

Simultaneous reconstruction of activity and attenuation in positron emission tomography without transmission data presents significant degradation due to crosstalk effect. The objective of this work is to investigate the effect of applying a priori knowledge, such as known attenuation coefficients, in some regions of the image, into a simultaneous activity and attenuation reconstruction algorithm (EM-AA). The methodology consists of applying, after each iteration, a global correction (addition) on the attenuation map, based on the difference between the known attenuation coefficient and the average of the estimated coefficients in the region. We also applied a correction factor that decreases with iteration number. The assessments were carried out via phantoms emulating 3D PET that presented specific features for crosstalk and structural accuracy measurements. We obtained three figures of merit for activity and three for attenuation. The results showed that, in the case of noiseless projections, the proposed correction improved the estimation of both activity and attenuation. On the other hand, while structural accuracy improved with iterations, the crosstalk effects become worse. The improvements were more pronounced for structural accuracy than for crosstalk effects. However, the errors are still too high, and more research is needed in this area.

show abstract

Section: Methodsmentioning

confidence: 99%

Simultaneous activity and attenuation reconstruction in PET: applying partially known attenuation

Furuie

2009

SPIE Proceedings

View full text Add to dashboard Cite

show abstract

“…It is also based on maximum likelihood, but using minorization function approach 5,6 . The algorithm for the activity turned out to be the same as EM-ML for attenuated projections 7,8 (Equation 1).…”

Section: Methodsmentioning

confidence: 99%

Simultaneous reconstruction of activity and attenuation in PET: crosstalk measurements

Furuie¹,

Pierro

Mascarenhas

et al. 2007

SPIE Proceedings

Self Cite

View full text Add to dashboard Cite

Quantitative tomographic reconstruction based on positron emission (PET) requires attenuation correction on projections. The objective of this work is to analyze an algorithm for attenuation estimation which is used simultaneously with activity reconstruction (PET-AA) based only on emission data. The focus is on measurement of crosstalk effects on activity due to non-uniform attenuation. The derived algorithms are based on maximization of likelihood, but using minorization function approach. The activity estimator turned out to be the same as EM-ML for attenuated projections. On the other hand, the proposed algorithm for attenuation is simple and, basically, corrects the previous estimation of attenuation in a voxel by the ratio between the backprojection of estimated projections and backprojection of measured projections. Preliminary assessments were carried out via tridimensional phantoms with non-uniform attenuation emulating 3D PET with and without noise. Individually, the algorithms for attenuation and activity presented very good results with negligible crosstalk and global reconstruction error less than 2% for noiseless projections. For the case of simultaneous estimation, even without noise, the crosstalks in estimating activity and attenuation are significant (-0.223 ± 0.051) yielding global errors for activity between 10% and 20%. With noise, the error increased to 36% and the crosstalk to (-0.688 ± 0.139). The proposed algorithm for attenuation estimation presents encouraging behavior and the results confirm the necessity of methodologies to deal with crosstalk effects in PET-AA.

show abstract

“…These algorithms either try to perform iterative inversion of the forward mathematical model, 16–19 or exploit the consistency conditions that are based on the forward model. 15, 20–22 However, these methods are considerably slow, and mostly use only the data around the photopeak events neglecting the scattered photons. The techniques have met with only limited success.…”

Section: Introductionmentioning

confidence: 99%

Joint reconstruction of activity and attenuation map using LM SPECT emission data

Jha

Clarkson

Kupinski

et al. 2013

Medical Imaging 2013: Physics of Medical Imaging

View full text Add to dashboard Cite

Attenuation and scatter correction in single photon emission computed tomography (SPECT) imaging often requires a computed tomography (CT) scan to compute the attenuation map of the patient. This results in increased radiation dose for the patient, and also has other disadvantages such as increased costs and hardware complexity. Attenuation in SPECT is a direct consequence of Compton scattering, and therefore, if the scattered photon data can give information about the attenuation map, then the CT scan may not be required. In this paper, we investigate the possibility of joint reconstruction of the activity and attenuation map using list-mode (LM) SPECT emission data, including the scattered-photon data. We propose a path-based formalism to process scattered-photon data. Following this, we derive analytic expressions to compute the Cramér-Rao bound (CRB) of the activity and attenuation map estimates, using which, we can explore the fundamental limit of information-retrieval capacity from LM SPECT emission data. We then suggest a maximum-likelihood (ML) scheme that uses the LM emission data to jointly reconstruct the activity and attenuation map. We also propose an expectation-maximization (EM) algorithm to compute the ML solution.

show abstract

Activity and Attenuation Reconstruction for Positron Emission Tomography Using Emission Data Only Via Maximum Likelihood and Iterative Data Refinement

Cited by 17 publications

References 21 publications

Simultaneous activity and attenuation reconstruction in PET: applying partially known attenuation

Simultaneous activity and attenuation reconstruction in PET: applying partially known attenuation

Simultaneous reconstruction of activity and attenuation in PET: crosstalk measurements

Joint reconstruction of activity and attenuation map using LM SPECT emission data

Contact Info

Product

Resources

About