A concave prior penalizing relative differences for maximum-a-posteriori reconstruction in emission tomography

Nuyts, Johan; Bequé, D.; Dupont, Patrick; Mortelmans, Luc

doi:10.1109/tns.2002.998681

Cited by 167 publications

(76 citation statements)

References 8 publications

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“…We reconstructed the measurement data with a listmode-based three-dimensional maximum likelihood expectation maximization algorithm including self-normalization and resolution recovery (MLEM-RM) (Salomon et al 2012). The reconstruction algorithm grouped the data into 16 ordered subsets with 5 sub-iterations each, regularized with a relative difference prior with dynamic edge preservation parameters (Andreyev et al 2017, Nuyts et al 2002), and used a voxel pitch of 0.25 mm. Additionally, the reconstruction employs a likelihood-based rejection of inter-crystal detector scatter (Gross-Weege et al 2016) and applied corrections for attenuation, scatter and randoms.…”

Section: Methodsmentioning

confidence: 99%

PET performance evaluation of the small-animal Hyperion II ^D PET/MRI insert based on the NEMA NU-4 standard

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Schug

Weissler

et al. 2018

Biomed. Phys. Eng. Express

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The Hyperion IID PET insert is the first scanner using fully digital silicon photomultipliers for simultaneous PET/MR imaging of small animals up to rabbit size. In this work, we evaluate the PET performance based on the National Eletrical Manufacturers Association (NEMA) NU 4-2008 standard, whose standardized measurement protocols allow comparison of different small-animal PET scanners. The Hyperion IID small-animal PET/MR insert comprises three rings of 20 detector stacks with pixelated scintillator arrays with a crystal pitch of 1 mm, read out with digital silicon photomultipliers. The scanner has a large ring diameter of 209.6 mm and an axial field of view of 96.7 mm. We evaluated the spatial resolution, energy resolution, time resolution and sensitivity by scanning a 22Na point source. The count rates and scatter fractions were measured for a wide range of 18F activity inside a mouse-sized scatter phantom. We evaluated the image quality using the mouse-sized image quality phantom specified in the NEMA NU4 standard, filled with 18F. Additionally, we verified the in-vivo imaging capabilities by performing a simultaneous PET/MRI scan of a mouse injected with 18F-FDG. We processed all measurement data with an energy window of 250 keV to 625 keV and a coincidence time window of 2 ns. The filtered-backprojection reconstruction of the point source has a full width at half maximum (FWHM) of 1.7 mm near the isocenter and degrades to 2.5 mm at a radial distance of 50 mm. The scanner’s average energy resolution is 12.7% (ΔE/E FWHM) and the coincidence resolution time is 609 ps. The peak absolute sensitivity is 4.0% and the true and noise-equivalent count rates reach their peak at an activity of 46 MBq with 483 kcps and 407 kcps, respectively, with a scatter fraction of 13%. The iterative reconstruction of the image quality phantom has a uniformity of 3.7%, and recovery coefficients from 0.29, 0.91 and 0.94 for rod diameters of 1 mm, 3 mm and 5 mm, respectively. After application of scatter and attenuation corrections, the air- and water-filled cold regions have spill-over ratios of 6.3% and 5.4%, respectively. The Hyperion IID PET/MR insert provides state-of-the-art PET performance while enabling simultaneous PET/MRI acquisition of small animals up to rabbit size.

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Section: Methodsmentioning

confidence: 99%

PET performance evaluation of the small-animal Hyperion II ^D PET/MRI insert based on the NEMA NU-4 standard

Hallen

Schug

Weissler

et al. 2018

Biomed. Phys. Eng. Express

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“…To prevent excessive noise propagation, the iterations can be stopped before full convergence, but at the expense of lesser quantitative accuracy. Alternatively, the objective function can be extended with a prior favouring smooth solutions [19] and such algorithms can achieve global convergence while retaining fast initial convergence speed [20]. Q.Clear, a Bayesian penalized likelihood technique, uses a relative difference penalty which is a function of the difference between neighbouring voxels as well as a function of their sum.…”

Section: Introductionmentioning

confidence: 99%

Performance characteristics of silicon photomultiplier based 15-cm AFOV TOF PET/CT

Vandendriessche

Uribe²,

Bertin³

et al. 2019

EJNMMI Phys

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Background This paper describes the National Electrical Manufacturers Association (NEMA) system performance of the Discovery MI 3-ring PET/CT (GE Healthcare) installed in Bruges, Belgium. This time-of-flight (TOF) PET camera is based on silicon photomultipliers instead of photomultiplier tubes. Methods The NEMA NU2-2012 standard was used to evaluate spatial resolution, sensitivity, image quality (IQ) and count rate curves of the system. Timing and energy resolution were determined. Results Full width at half maximum (FWHM) of spatial resolution in radial, tangential and axial direction was 4.69, 4.08 and 4.68 mm at 1 cm; 5.58, 4.64 and 5.83 mm at 10 cm; and 7.53, 5.08 and 5.47 mm at 20 cm from the centre of the field of view (FOV) for the filtered backprojection reconstruction. For non-TOF ordered subset expectation maximization (OSEM) reconstruction without point spread function (PSF) correction, FWHM was 3.87, 3.69 and 4.15 mm at 1 cm; 4.80, 3.81 and 4.87 mm at 10 cm; and 7.38, 4.16 and 3.98 mm at 20 cm. Sensitivity was 7.258 cps/kBq at the centre of the FOV and 7.117 cps/kBq at 10-cm radial offset. Contrast recovery (CR) using the IQ phantom for the TOF OSEM reconstruction without PSF correction was 47.4, 59.3, 67.0 and 77.0% for the 10-, 13-, 17- and 22-mm radioactive spheres and 82.5 and 85.1% for the 28- and 37-mm non-radioactive spheres. Background variability (BV) was 16.4, 12.1, 9.1, 6.6, 5.1 and 3.8% for the 10-, 13-, 17-, 22-, 28- and 37-mm spheres. Lung error was 8.5%. Peak noise equivalent count rate (NECR) was 102.3 kcps at 23.0 kBq/ml with a scatter fraction of 41.2%. Maximum accuracy error was 3.88%. Coincidence timing resolution was 375.6 ps FWHM. Energy resolution was 9.3% FWHM. Q.Clear reconstruction significantly improved CR and reduced BV compared with OSEM. Conclusion System sensitivity and NECR are lower and IQ phantom’s BV is higher compared with larger axial FOV (AFOV) scanners like the 4-ring discovery MI, as expected from the smaller solid angle of the 3-ring system. The other NEMA performance parameters are all comparable with those of the larger AFOV scanners.

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“…The Q.Clear protocol is a Bayesian penalized likelihood reconstruction algorithm which incorporates a penalty factor to control noise [13]. It includes time of flight (TOF) and point spread function (PSF), taking into account resolution-degrading effects such as positron range, photon non-collinearity, and detector-related effects including crystal widths, inter-crystal scattering, and inter-crystal penetration (depth of interaction effects).…”

Section: Methodsmentioning

confidence: 99%

Impact of PET reconstruction protocols on quantification of lesions that fulfil the PERCIST lesion inclusion criteria

et al. 2018

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BackgroundThe aim of this study was to compare liver and oncologic lesion standardized uptake values (SUV) obtained through two different reconstruction protocols, GE’s newest clinical lesion detection protocol (Q.Clear) and the EANM Research Ltd (EARL) harmonization protocol, and to assess the clinical relevance of potential differences and possible implications for daily clinical practice using the PERCIST lesional inclusion criteria.NEMA phantom recovery coefficients (RC) and SUV normalized for lean body mass (LBM), referred to as SUV normalized for LBM (SUL), of liver and lesion volumes of interest were compared between the two reconstruction protocols. Head-to-toe PET/CT examinations and raw data from 64 patients were retrospectively retrieved. PET image reconstruction was carried out twice: once optimized for quantification, complying with EARL accreditation requirements, and once optimized for lesion detection, according to GE’s Q.Clear reconstruction settings.ResultsThe two reconstruction protocols showed different NEMA phantom RC values for different sphere sizes. Q.Clear values were always highest and exceeded the EARL accreditation maximum for smaller spheres. Comparison of liver SULmean showed a statistically significant but clinically irrelevant difference between both protocols. Comparison of lesion SULpeak and SULmax showed a statistically significant, and clinically relevant, difference of 1.64 and 4.57, respectively.ConclusionsFor treatment response assessment using PERCIST criteria, the harmonization reconstruction protocol should be used as the lesion detection reconstruction protocol using resolution recovery systematically overestimates true SUL values.

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A concave prior penalizing relative differences for maximum-a-posteriori reconstruction in emission tomography

Cited by 167 publications

References 8 publications

PET performance evaluation of the small-animal Hyperion II ^D PET/MRI insert based on the NEMA NU-4 standard

PET performance evaluation of the small-animal Hyperion II ^D PET/MRI insert based on the NEMA NU-4 standard

Performance characteristics of silicon photomultiplier based 15-cm AFOV TOF PET/CT

Impact of PET reconstruction protocols on quantification of lesions that fulfil the PERCIST lesion inclusion criteria

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A concave prior penalizing relative differences for maximum-a-posteriori reconstruction in emission tomography

Cited by 167 publications

References 8 publications

PET performance evaluation of the small-animal Hyperion II D PET/MRI insert based on the NEMA NU-4 standard

PET performance evaluation of the small-animal Hyperion II D PET/MRI insert based on the NEMA NU-4 standard

Performance characteristics of silicon photomultiplier based 15-cm AFOV TOF PET/CT

Impact of PET reconstruction protocols on quantification of lesions that fulfil the PERCIST lesion inclusion criteria

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PET performance evaluation of the small-animal Hyperion II ^D PET/MRI insert based on the NEMA NU-4 standard

PET performance evaluation of the small-animal Hyperion II ^D PET/MRI insert based on the NEMA NU-4 standard