Journal ArticleDOI
Simultaneous maximum a posteriori reconstruction of attenuation and activity distributions from emission sinograms
TLDR
A new method to compute an attenuation map directly from the emission sinogram, eliminating the transmission scan from the acquisition protocol is proposed, which has been tested on mathematical phantoms and on a few clinical studies.Abstract:
In order to perform attenuation correction in emission tomography an attenuation map is required. The authors propose a new method to compute this map directly from the emission sinogram, eliminating the transmission scan from the acquisition protocol. The problem is formulated as an optimization task where the objective function is a combination of the likelihood and an a priori probability. The latter uses a Gibbs prior distribution to encourage local smoothness and a multimodal distribution for the attenuation coefficients. Since the attenuation process is different in positron emission tomography (PET) and single photon emission tomography (SPECT), a separate algorithm for each case is derived. The method has been tested on mathematical phantoms and on a few clinical studies. For PET, good agreement was found between the images obtained with transmission measurements and those produced by the new algorithm in an abdominal study. For SPECT, promising simulation results have been obtained for nonhomogeneous attenuation due to the presence of the lungs.read more
Citations
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Journal Article
Determination of the Attenuation Map in Emission Tomography
Habib Zaidi,Bruce H. Hasegawa +1 more
TL;DR: The physical and methodologic basis of attenuation correction is presented and recent developments in algorithms used to compute the attenuation map in ECT are summarized.
Journal ArticleDOI
Magnetic resonance imaging-guided attenuation and scatter corrections in three-dimensional brain positron emission tomography.
TL;DR: MRI-based attenuation correction in 3D brain PET would likely be the method of choice for the foreseeable future as a second best approach in a busy nuclear medicine center and could be applied to other functional brain imaging modalities such as SPECT.
Journal ArticleDOI
MRI-Based Attenuation Correction for Whole-Body PET/MRI: Quantitative Evaluation of Segmentation- and Atlas-Based Methods
Matthias Hofmann,Ilja Bezrukov,Frederic Mantlik,Philip Aschoff,Florian Steinke,Thomas Beyer,Bernd J. Pichler,Bernhard Schölkopf +7 more
TL;DR: The MRAC method using AT&PR provided better overall PET quantification accuracy than the basic MR image segmentation approach, due to the significantly reduced volume of errors made regarding volumes of interest within or near bones and the slightly reducedVolume of errorsmade regarding areas outside the lungs.
Journal ArticleDOI
Recent developments in time-of-flight PET
TL;DR: Recent developments in system design, image reconstruction, corrections, and the potential in new applications for TOF-PET are reviewed to introduce the reader in an educational way into the topic of time-of-flight-PET.
Journal ArticleDOI
Reduction of metal streak artifacts in X-ray computed tomography using a transmission maximum a posteriori algorithm
TL;DR: In this paper, a maximum a posteriori algorithm for reduction of metal streak artifacts in X-ray computed tomography is presented, which uses a Markov random field smoothness prior and applies increased sampling in the reconstructed image.
References
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Journal ArticleDOI
Stochastic Relaxation, Gibbs Distributions, and the Bayesian Restoration of Images
Stuart Geman,Donald Geman +1 more
TL;DR: The analogy between images and statistical mechanics systems is made and the analogous operation under the posterior distribution yields the maximum a posteriori (MAP) estimate of the image given the degraded observations, creating a highly parallel ``relaxation'' algorithm for MAP estimation.
Journal ArticleDOI
Maximum Likelihood Reconstruction for Emission Tomography
L. A. Shepp,Y. Vardi +1 more
TL;DR: In this paper, the authors proposed a more accurate general mathematical model for ET where an unknown emission density generates, and is to be reconstructed from, the number of counts n*(d) in each of D detector units d. Within the model, they gave an algorithm for determining an estimate? of? which maximizes the probability p(n*|?) of observing the actual detector count data n* over all possible densities?.
Journal ArticleDOI
Accelerated image reconstruction using ordered subsets of projection data
H.M. Hudson,R.S. Larkin +1 more
TL;DR: Ordered subsets EM (OS-EM) provides a restoration imposing a natural positivity condition and with close links to the EM algorithm, applicable in both single photon (SPECT) and positron emission tomography (PET).
Journal Article
EM reconstruction algorithms for emission and transmission tomography.
Kenneth Lange,Richard E. Carson +1 more
TL;DR: The general principles behind all EM algorithms are discussed and in detail the specific algorithms for emission and transmission tomography are derived and the specification of necessary physical features such as source and detector geometries are discussed.
Journal ArticleDOI
Maximum likelihood reconstruction for emission tomography
L. A. Shepp,Y. Vardi +1 more
TL;DR: A more accurate general mathematical model where an unknown emission density ¿ = x, y, z generates, and is to be reconstructed from, the number of counts n*(d) in each of D detector units d is given.
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