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Published on: July 10, 2019
MicroPET reconstruction with random coincidence correction via a joint Poisson model
Tai-Been Chen1, Jyh-Cheng Chen, Henry Horng-Shing Lu
1Department of Medical Imaging and Radiological Sciences, I-Shou University, Taiwan, ROC.
Abstract:
Positron emission tomography (PET) can provide in vivo, quantitative and functional information for diagnosis; however, PET image quality depends highly on a reconstruction algorithm. Iterative algorithms, such as the maximum likelihood expectation maximization (MLEM) algorithm, are rapidly becoming the standards for image reconstruction in emission-computed tomography. The conventional MLEM algorithm utilized the Poisson model in its system matrix, which is no longer valid for delay-subtraction of randomly corrected data. The aim of this study is to overcome this problem. The maximum likelihood estimation using the expectation maximum algorithm (MLE-EM) is adopted and modified to reconstruct microPET images using random correction from joint prompt and delay sinograms; this reconstruction method is called PDEM. The proposed joint Poisson model preserves Poisson properties without increasing the variance (noise) associated with random correction. The work here is an initial application/demonstration without applied normalization, scattering, attenuation, and arc correction. The coefficients of variation (CV) and full width at half-maximum (FWHM) values were utilized to compare the quality of reconstructed microPET images of physical phantoms acquired by filtered backprojection (FBP), ordered subsets-expected maximum (OSEM) and PDEM approaches. Experimental and simulated results demonstrate that the proposed PDEM produces better image quality than the FBP and OSEM approaches.
Insights
A new Positron Emission Tomography (PET) image reconstruction method, PDEM, improves image quality by using a joint Poisson model for random correction. This method enhances diagnostic accuracy in microPET imaging compared to traditional algorithms.
Area of Science:
- Medical Imaging
- Nuclear Medicine
- Image Reconstruction
Background:
- Positron Emission Tomography (PET) provides crucial in vivo quantitative and functional data for diagnosis.
- PET image quality is highly dependent on the reconstruction algorithm used.
- Conventional Maximum Likelihood Expectation Maximization (MLEM) algorithms are standard but fail with randomly corrected data due to invalid Poisson models.
Purpose of the Study:
- To address the limitations of conventional MLEM for randomly corrected PET data.
- To develop and validate a modified iterative algorithm for microPET image reconstruction.
- To improve the accuracy and quality of PET images, particularly when handling random coincidences.
Main Methods:
- Modified the Maximum Likelihood Expectation Maximization (MLEM) algorithm, termed PDEM (Positron Emission Tomography using joint Poisson model with Expectation-Maximization).
- Utilized a joint Poisson model to preserve Poisson properties in the system matrix for randomly corrected data.
- Reconstructed microPET images using joint prompt and delay sinograms, comparing PDEM against Filtered Backprojection (FBP) and Ordered Subsets-Expectation Maximization (OSEM).
Main Results:
- The PDEM algorithm successfully reconstructed microPET images using random correction from joint sinograms.
- The proposed joint Poisson model maintained Poisson properties without increasing noise variance.
- Quantitative analysis using Coefficients of Variation (CV) and Full Width at Half Maximum (FWHM) showed superior image quality with PDEM.
Conclusions:
- The PDEM reconstruction method offers improved microPET image quality compared to FBP and OSEM.
- PDEM provides a viable solution for accurate PET image reconstruction with randomly corrected data.
- This initial demonstration highlights PDEM's potential for enhanced diagnostic capabilities in PET imaging.
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