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Title: Iterative three-dimensional expectation maximization restoration of single photon emission computed tomography images: Application in striatal imaging

Abstract

Single photon emission computed tomography imaging suffers from poor spatial resolution and high statistical noise. Consequently, the contrast of small structures is reduced, the visual detection of defects is limited and precise quantification is difficult. To improve the contrast, it is possible to include the spatially variant point spread function of the detection system into the iterative reconstruction algorithm. This kind of method is well known to be effective, but time consuming. We have developed a faster method to account for the spatial resolution loss in three dimensions, based on a postreconstruction restoration method. The method uses two steps. First, a noncorrected iterative ordered subsets expectation maximization (OSEM) reconstruction is performed and, in the second step, a three-dimensional (3D) iterative maximum likelihood expectation maximization (ML-EM) a posteriori spatial restoration of the reconstructed volume is done. In this paper, we compare to the standard OSEM-3D method, in three studies (two in simulation and one from experimental data). In the two first studies, contrast, noise, and visual detection of defects are studied. In the third study, a quantitative analysis is performed from data obtained with an anthropomorphic striatal phantom filled with 123-I. From the simulations, we demonstrate that contrast as a functionmore » of noise and lesion detectability are very similar for both OSEM-3D and OSEM-R methods. In the experimental study, we obtained very similar values of activity-quantification ratios for different regions in the brain. The advantage of OSEM-R compared to OSEM-3D is a substantial gain of processing time. This gain depends on several factors. In a typical situation, for a 128x128 acquisition of 120 projections, OSEM-R is 13 or 25 times faster than OSEM-3D, depending on the calculation method used in the iterative restoration. In this paper, the OSEM-R method is tested with the approximation of depth independent resolution. For the striatum this approximation is appropriate, but for other clinical situations we will need to include a spatially varying response. Such a response is already included in OSEM-3D.« less

Authors:
; ; ; ; ; ;  [1];  [2];  [3];  [3];  [3];  [3]
  1. Laboratoire de Biophysique EA3033, Universite Paul Sabatier, Toulouse, (France)
  2. (Canada)
  3. (France)
Publication Date:
OSTI Identifier:
20774986
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 33; Journal Issue: 1; Other Information: DOI: 10.1118/1.2135908; (c) 2006 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; ALGORITHMS; APPROXIMATIONS; BIOLOGICAL RECOVERY; BRAIN; IMAGE PROCESSING; IMAGES; IODINE 123; ITERATIVE METHODS; MAXIMUM-LIKELIHOOD FIT; NOISE; PHANTOMS; SIMULATION; SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY; SPATIAL RESOLUTION; THREE-DIMENSIONAL CALCULATIONS; TRANSFER FUNCTIONS

Citation Formats

Gantet, Pierre, Payoux, Pierre, Celler, Anna, Majorel, Cynthia, Gourion, Daniel, Noll, Dominikus, Esquerre, Jean-Paul, Division of Nuclear Medicine, Vancouver Hospital and Health Sciences Centre, Vancouver, British Columbia,, Laboratoire de Biophysique EA3033, Universite Paul Sabatier, Toulouse,, Laboratoire d'Analyse non lineaire et de geometrie, Faculte des sciences, Avignon,, Mathematiques pour l'Industrie et la Physique, Universite Paul Sabatier, Toulouse,, and Laboratoire de Biophysique EA3033, Universite Paul Sabatier, Toulouse,. Iterative three-dimensional expectation maximization restoration of single photon emission computed tomography images: Application in striatal imaging. United States: N. p., 2006. Web. doi:10.1118/1.2135908.
Gantet, Pierre, Payoux, Pierre, Celler, Anna, Majorel, Cynthia, Gourion, Daniel, Noll, Dominikus, Esquerre, Jean-Paul, Division of Nuclear Medicine, Vancouver Hospital and Health Sciences Centre, Vancouver, British Columbia,, Laboratoire de Biophysique EA3033, Universite Paul Sabatier, Toulouse,, Laboratoire d'Analyse non lineaire et de geometrie, Faculte des sciences, Avignon,, Mathematiques pour l'Industrie et la Physique, Universite Paul Sabatier, Toulouse,, & Laboratoire de Biophysique EA3033, Universite Paul Sabatier, Toulouse,. Iterative three-dimensional expectation maximization restoration of single photon emission computed tomography images: Application in striatal imaging. United States. doi:10.1118/1.2135908.
Gantet, Pierre, Payoux, Pierre, Celler, Anna, Majorel, Cynthia, Gourion, Daniel, Noll, Dominikus, Esquerre, Jean-Paul, Division of Nuclear Medicine, Vancouver Hospital and Health Sciences Centre, Vancouver, British Columbia,, Laboratoire de Biophysique EA3033, Universite Paul Sabatier, Toulouse,, Laboratoire d'Analyse non lineaire et de geometrie, Faculte des sciences, Avignon,, Mathematiques pour l'Industrie et la Physique, Universite Paul Sabatier, Toulouse,, and Laboratoire de Biophysique EA3033, Universite Paul Sabatier, Toulouse,. Sun . "Iterative three-dimensional expectation maximization restoration of single photon emission computed tomography images: Application in striatal imaging". United States. doi:10.1118/1.2135908.
@article{osti_20774986,
title = {Iterative three-dimensional expectation maximization restoration of single photon emission computed tomography images: Application in striatal imaging},
author = {Gantet, Pierre and Payoux, Pierre and Celler, Anna and Majorel, Cynthia and Gourion, Daniel and Noll, Dominikus and Esquerre, Jean-Paul and Division of Nuclear Medicine, Vancouver Hospital and Health Sciences Centre, Vancouver, British Columbia, and Laboratoire de Biophysique EA3033, Universite Paul Sabatier, Toulouse, and Laboratoire d'Analyse non lineaire et de geometrie, Faculte des sciences, Avignon, and Mathematiques pour l'Industrie et la Physique, Universite Paul Sabatier, Toulouse, and Laboratoire de Biophysique EA3033, Universite Paul Sabatier, Toulouse,},
abstractNote = {Single photon emission computed tomography imaging suffers from poor spatial resolution and high statistical noise. Consequently, the contrast of small structures is reduced, the visual detection of defects is limited and precise quantification is difficult. To improve the contrast, it is possible to include the spatially variant point spread function of the detection system into the iterative reconstruction algorithm. This kind of method is well known to be effective, but time consuming. We have developed a faster method to account for the spatial resolution loss in three dimensions, based on a postreconstruction restoration method. The method uses two steps. First, a noncorrected iterative ordered subsets expectation maximization (OSEM) reconstruction is performed and, in the second step, a three-dimensional (3D) iterative maximum likelihood expectation maximization (ML-EM) a posteriori spatial restoration of the reconstructed volume is done. In this paper, we compare to the standard OSEM-3D method, in three studies (two in simulation and one from experimental data). In the two first studies, contrast, noise, and visual detection of defects are studied. In the third study, a quantitative analysis is performed from data obtained with an anthropomorphic striatal phantom filled with 123-I. From the simulations, we demonstrate that contrast as a function of noise and lesion detectability are very similar for both OSEM-3D and OSEM-R methods. In the experimental study, we obtained very similar values of activity-quantification ratios for different regions in the brain. The advantage of OSEM-R compared to OSEM-3D is a substantial gain of processing time. This gain depends on several factors. In a typical situation, for a 128x128 acquisition of 120 projections, OSEM-R is 13 or 25 times faster than OSEM-3D, depending on the calculation method used in the iterative restoration. In this paper, the OSEM-R method is tested with the approximation of depth independent resolution. For the striatum this approximation is appropriate, but for other clinical situations we will need to include a spatially varying response. Such a response is already included in OSEM-3D.},
doi = {10.1118/1.2135908},
journal = {Medical Physics},
number = 1,
volume = 33,
place = {United States},
year = {Sun Jan 15 00:00:00 EST 2006},
month = {Sun Jan 15 00:00:00 EST 2006}
}
  • Restoration of single photon emission computed tomography (SPECT) images is usually performed either on two-dimensional (2-D) projection images (pre-reconstruction restoration) or on SPECT slices (post-reconstruction restoration). This study presents the application of a three-dimensional (3-D) filter in restoring SPECT images. The 3-D filter is shown to perform better than the 2-D methods because it takes into consideration the interslice information in the filtering process and has a relatively space-invariant blur function. To reduce the space-variance of the 3-D point spread function (PSF), conjugate projections were combined by geometric averaging before reconstruction. The authors investigated the potential of 3-D Wiener andmore » power spectrum equalization (PSE) filters. These filters were applied to SPECT images of a resolution phantom and a large, truncated cone phantom containing two types of cold spots: a sphere, and a triangular prism. The filters were also applied to clinical images of the liver and spleen. The images were acquired on an ADAC GENESYS camera. A comparison was performed between results obtained in this study and those obtained by 2-D pre-reconstruction restoration and 2-D post-reconstruction restoration filters. Quantitative analysis of the 3-D restored images performed through measurement of root mean squared (RMS) errors and contrast ratios showed a considerable reduction in error and increase in contrast over images restored using the two other methods.« less
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