Comparison of 3D-OP-OSEM and 3D-FBP reconstruction algorithms for High-Resolution Research Tomograph studies: effects of randoms estimation methods

Velden, Floris H. P. van; Kloet, Reina W.; Berckel, Bart N.M. van; Wolfensberger, Saskia P.A.; Lammertsma, Adriaan A.; Boellaard, Ronald

doi:10.1088/0031-9155/53/12/010

Cited by 37 publications

(42 citation statements)

References 26 publications

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“…For the Hoffman phantom decay study, ANW-OSEM performed poorly, with a change in the GM-to-WM contrast ratio of 20%. In a previous study (9), we reported a high-contrast change in the GM-to-WM contrast ratio (54%) using the manufacturer's implementation of OP-OSEM. Using the in-house-implemented OP-OSEM with the same convergence criteria, the same ROI definitions, and the same scan of the Hoffman phantom, we obtained a good (and stable) GM-to-WM contrast ratio (10%), as we did with most other reconstruction methods (between 8% and 10%).…”

Section: Phantom Studiesmentioning

confidence: 92%

“…Further improvements were expected by using the VRR algorithm (5), which estimates expected randoms (v i ) from measured delayed coincidences (9). The mathematic formulae are the same, except that v i is used instead of d i, and the trues (t i ) are calculated by p i 2 v i .…”

Section: Reconstruction Algorithmsmentioning

confidence: 99%

“…The sinogram data were filtered using a Colsher filter (24) (cutoff at the Nyquist frequency), without additional smoothing. 3D-FBP should be used in combination with the VRR algorithm to improve precision (9). A detailed description of 3D-FBP for the HRRT has been described previously (8).…”

Section: Reconstruction Algorithmsmentioning

confidence: 99%

“…Missing data were estimated by gap-filling strategies, which will be described in more detail later in this article. 3D-FBP showed a higher precision when used in combination with the VRR algorithm (9). Yavuz and Fessler (10) showed that shifted Poisson OSEM (SP-OSEM) reconstruction, compared with OP-OSEM reconstruction, reduced bias and provided better precision.…”

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confidence: 99%

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Accuracy of 3-Dimensional Reconstruction Algorithms for the High-Resolution Research Tomograph

et al. 2008

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The high-resolution research tomograph (HRRT) is a dedicated human brain PET scanner. At present, iterative reconstruction methods are preferred for reconstructing HRRT studies. However, these iterative reconstruction algorithms show bias in short-duration frames. New algorithms such as the shifted Poisson ordered-subsets expectation maximization (SP-OSEM) and ordered-subsets weighted least squares (OSWLS) showed promising results in bias reduction, compared with the recommended ordinary Poisson OSEM (OP-OSEM). The goal of this study was to evaluate quantitative accuracy of these iterative reconstruction algorithms, compared with 3-dimensional filtered backprojection (3D-FBP). Methods: The 3 above-mentioned 3D iterative reconstruction methods were implemented for the HRRT. To evaluate the various 3D iterative reconstruction techniques quantitatively, several phantom studies and a human brain study (n 5 5) were performed. Results: OSWLS showed a low and almost linearly increasing coefficient of variation (SD over average activity concentration), with decreasing noise-equivalent count rates. In decay studies, OSWLS showed good agreement with the 3D-FBP gray matter (GM)-to-white matter (WM) contrast ratio (,4%), and OP-OSEM and SP-OSEM showed agreement within 6% and 7%, respectively. For various frame durations, both SP-OSEM and OP-OSEM showed the fewest errors in GM-to-WM contrast ratios, varying 75% between different noise-equivalent count rates; this variability was much higher for other iterative methods (.92%). 3D-FBP showed the least variability (34%). Visually, OSWLS hardly showed any artifacts in parametric images and showed good agreement with 3D-FBP data for parametric images, especially in the case of reference-tissue kinetic methods (slope, 1.02; Pearson correlation coefficient, 0.99). Conclusion: OP-OSEM, SP-OSEM, and OSWLS showed good performance for phantom studies. In addition, OSWLS showed better results for parametric analysis of clinical studies and is therefore recommended for quantitative HRRT brain PET studies.

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Section: Phantom Studiesmentioning

confidence: 92%

Section: Reconstruction Algorithmsmentioning

confidence: 99%

Section: Reconstruction Algorithmsmentioning

confidence: 99%

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confidence: 99%

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Accuracy of 3-Dimensional Reconstruction Algorithms for the High-Resolution Research Tomograph

et al. 2008

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“…23,24 Nevertheless, noise reduction with a better TOF resolution (i.e., better effective sensitivity) and running lower number of OSEM updates was demonstrated to be able to minimize the bias in both µ-map and emission image as expected. Based on these results, the new generation of TOF PET scanners which employ digital PET detectors with 300-400 ps TOF resolution is expected to improve the accuracy of the proposed method at low count situations.…”

Section: Discussionmentioning

confidence: 63%

Investigation of practical initial attenuation image estimates in TOF‐MLAA reconstruction for PET/MR

et al. 2016

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Purpose: Time-of-flight joint attenuation and activity positron emission tomography reconstruction requires additional calibration (scale factors) or constraints during or post-reconstruction to produce a quantitative µ-map. In this work, the impact of various initializations of the joint reconstruction was investigated, and the initial average mu-value (IAM) method was introduced such that the forward-projection of the initial µ-map is already very close to that of the reference µ-map, thus reducing/minimizing the offset (scale factor) during the early iterations of the joint reconstruction. Consequently, the accuracy and efficiency of unconstrained joint reconstruction such as time-of-flight maximum likelihood estimation of attenuation and activity (TOF-MLAA) can be improved by the proposed IAM method. Methods: 2D simulations of brain and chest were used to evaluate TOF-MLAA with various initial estimates which include the object filled with water uniformly (conventional initial estimate), bone uniformly, the average µ-value uniformly (IAM magnitude initialization method), and the perfect spatial µ-distribution but with a wrong magnitude (initialization in terms of distribution). 3D  simulation was also performed for the chest phantom under a typical clinical scanning condition, and the simulated data were reconstructed with a fully corrected list-mode TOF-MLAA algorithm with various initial estimates. The accuracy of the average µ-values within the brain, chest, and abdomen regions obtained from the MR derived µ-maps was also evaluated using computed tomography µ-maps as the gold-standard. Results: The estimated µ-map with the initialization in terms of magnitude (i.e., average µ-value) was observed to reach the reference more quickly and naturally as compared to all other cases. Both 2D and 3D  simulations produced similar results, and it was observed that the proposed IAM approach can produce quantitative µ-map/emission when the corrections for physical effects such as scatter and randoms were included. The average µ-value obtained from MR derived µ-map was accurate within 5% with corrections for bone, fat, and uniform lungs. Conclusions: The proposed IAM-TOF-MLAA can produce quantitative µ-map without any calibration provided that there are sufficient counts in the measured data. For low count data, noise reduction and additional regularization/rescaling techniques need to be applied and investigated. The average µ-value within the object is prior information which can be extracted from MR and patient database, and it is feasible to obtain accurate average µ-value using MR derived µ-map with corrections as demonstrated in this work. C

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mGluR5 receptor availability is associated with lower levels of negative symptoms and better cognition in male patients with chronic schizophrenia

Brambilla

Veselinović

Rajkumar

et al. 2020

Human Brain Mapping

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Consistent findings postulate disturbed glutamatergic function (more specifically a hypofunction of the ionotropic NMDA receptors) as an important pathophysiologic mechanism in schizophrenia. However, the role of the metabotropic glutamatergic receptors type 5 (mGluR5) in this disease remains unclear. In this study, we investigated their significance (using [11C]ABP688) for psychopathology and cognition in male patients with chronic schizophrenia and healthy controls. In the patient group, lower mGluR5 binding potential (BPND) values in the left temporal cortex and caudate were associated with higher general symptom levels (negative and depressive symptoms), lower levels of global functioning and worse cognitive performance. At the same time, in both groups, mGluR5 BPND were significantly lower in smokers (F[27,1] = 15.500; p = .001), but without significant differences between the groups. Our findings provide support for the concept that the impaired function of mGluR5 underlies the symptoms of schizophrenia. They further supply a new perspective on the complex relationship between tobacco addiction and schizophrenia by identifying glutamatergic neurotransmission—in particularly mGluR5—as a possible connection to a shared vulnerability.

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Comparison of 3D-OP-OSEM and 3D-FBP reconstruction algorithms for High-Resolution Research Tomograph studies: effects of randoms estimation methods

Cited by 37 publications

References 26 publications

Accuracy of 3-Dimensional Reconstruction Algorithms for the High-Resolution Research Tomograph

Accuracy of 3-Dimensional Reconstruction Algorithms for the High-Resolution Research Tomograph

Investigation of practical initial attenuation image estimates in TOF‐MLAA reconstruction for PET/MR

mGluR5 receptor availability is associated with lower levels of negative symptoms and better cognition in male patients with chronic schizophrenia

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