PET iterative reconstruction incorporating an efficient positron range correction method

Bertolli, Ottavia; Eleftheriou, Afroditi; Cecchetti, Matteo; Camarlinghi, N.; Belcari, Nicola; Tsoumpas, Charalampos

doi:10.1016/j.ejmp.2015.11.005

Cited by 36 publications

(40 citation statements)

References 22 publications

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“…Although the abovementioned studies show promising results with 2-deoxy-2-[ 18 F]-fluoro-D-glucose ( 18 F-FDG) on PET, the situation could be different for the 68 Gallium-labeled tracer targeting the prostate-specific membrane antigen ( 68 Ga-PSMA) as it has a clearly different uptake pattern compared to the 18 F-FDG tracer used in most studies. The low background activity, higher tumor to background ratios, higher positron energy, and larger positron range could, e.g., have an effect on the performance [ 20 , 26 ]. Moreover, previous studies were performed on PET/computed tomography (CT) whereas in this study, a PET/magnetic resonance (MR) is applied.…”

Section: Introductionmentioning

confidence: 99%

Quantitative performance and optimal regularization parameter in block sequential regularized expectation maximization reconstructions in clinical 68Ga-PSMA PET/MR

Voert

Muehlematter

Delso³

et al. 2018

EJNMMI Res

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BackgroundIn contrast to ordered subset expectation maximization (OSEM), block sequential regularized expectation maximization (BSREM) positron emission tomography (PET) reconstruction algorithms can run until full convergence while controlling image quality and noise. Recent studies with BSREM and 18F-FDG PET reported higher signal-to-noise ratios and higher standardized uptake values (SUV). In this study, we investigate the optimal regularization parameter (β) for clinical 68Ga-PSMA PET/MR reconstructions in the pelvic region applying time-of-flight (TOF) BSREM in comparison to TOF OSEM.Two-minute emission data from the pelvic region of 25 patients who underwent 68Ga-PSMA PET/MR were retrospectively reconstructed. Reference OSEM reconstructions had 28 subsets and 2 iterations. BSREM reconstructions were performed with 15 β values between 150 and 1200. Regions of interest (ROIs) were drawn around lesions and in uniform background. Background SUVmean (average) and SUVstd (standard deviation), and lesion SUVmax (average of 5 hottest voxels) were calculated. Differences were analyzed using the Wilcoxon matched pairs signed-rank test.ResultsA total of 40 lesions were identified in the pelvic region. Background noise (SUVstd) and lesions SUVmax decreased with increasing β. Image reconstructions with β values lower than 400 have higher (p < 0.01) background noise, compared to the reference OSEM reconstructions, and are therefore less useful. Lesions with low activity on images reconstructed with β values higher than 600 have a lower (p < 0.05) SUVmax compared to the reference. These reconstructions are likely visually appealing due to the lower background noise, but the lower SUVmax could possibly render small low-uptake lesions invisible.ConclusionsIn our study, we showed that PET images reconstructed with TOF BSREM in combination with the 68Ga-PSMA tracer result in lower background noise and higher SUVmax values in lesions compared to TOF OSEM. Our study indicates that a β value between 400 and 550 might be the optimal compromise between high SUVmax and low background noise.Electronic supplementary materialThe online version of this article (10.1186/s13550-018-0414-4) contains supplementary material, which is available to authorized users.

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Section: Introductionmentioning

confidence: 99%

Quantitative performance and optimal regularization parameter in block sequential regularized expectation maximization reconstructions in clinical 68Ga-PSMA PET/MR

Voert

Muehlematter

Delso³

et al. 2018

EJNMMI Res

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“…On average, 11 C had a fitting error of 2% , 10 C had a fitting error of 8%, 15 O had a fitting error of 1.5% of the initial weight value.…”

Section: Resultsmentioning

confidence: 99%

“…With the 16 O beam (Table 6), BIC produces the overall best match for positron production (performing best in 5 of the 6 combinations of energy and phantom). The production of 15 O is best modelled by BIC in most cases; again, 10 C production is overestimated by all models compared to the fitted experimental data.…”

Section: Build-up and Bragg Peak Regionmentioning

confidence: 88%

Comparative study of alternative Geant4 hadronic ion inelastic physics models for prediction of positron-emitting radionuclide production in carbon and oxygen ion therapy

et al. 2019

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“…Indeed, detectordependent factors, such as crystal size and crystal penetration during detection, and inherent limitations such as the noncollinearity of the annihilation photons are also present and can explain why a reduced positron range with an increasing FIGURE 6 | Spatial distribution of the simulated annihilation endpoints in the z/y plane parallel to the magnetic field for a 68 Ga point source positioned at the interface between lung and soft tissue (dashed black line) for a field strength of 0 T (left) and 3 T (right). magnetic field does not translate directly into improved image quality (Herzog et al, 2010;Bertolli et al, 2016;Caribé et al, 2019;Wadhwa et al, 2020). However, in a preclinical setting with small diameter detector rings and crystal sizes, the impact of a reduced positron range on the PET image quality is expected to be much higher while the use of monolithic crystals or recordings of the depth of interaction in clinical PET systems can further enhance the PET resolution such that it becomes more sensitive to positron range effects (Hammer et al, 1994;Stockhoff et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

Monte Carlo Simulations of the GE Signa PET/MR for Different Radioisotopes

et al. 2020

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NEMA characterization of PET systems is generally based on 18 F because it is the most relevant radioisotope for the clinical use of PET. 18 F has a half-life of 109.7 min and decays into stable 18 O via β+ emission with a probability of over 96% and a maximum positron energy of 0.633 MeV. Other commercially available PET radioisotopes, such as 82 Rb and 68 Ga have more complex decay schemes with a variety of prompt gammas, which can directly fall into the energy window and induce false coincidence detections by the PET scanner. Methods: Aim of this work was threefold: (A) Develop a GATE model of the GE Signa PET/MR to perform realistic and relevant Monte Carlo simulations (B) Validate this model with published sensitivity and Noise Equivalent Count Rate (NECR) data for 18 F and 68 Ga (C) Use the validated GATE-model to predict the system performance for other PET isotopes including 11 C, 15 O, 13 N, 82 Rb, and 68 Ga and to evaluate the effect of a 3T magnetic field on the positron range. Results: Simulated sensitivity and NECR tests performed with the GATE-model for different radioisotopes were in line with literature values. Simulated sensitivities for 18 F and 68 Ga were 21.2 and 19.0 /kBq, respectively, for the center position and 21.1 and 19.0 cps/kBq, respectively, for the 10 cm off-center position compared to the corresponding measured values of 21.8 and 20.0 cps/kBq for the center position and 21.1 and 19.6 cps/kBq for the 10 cm off-center position. In terms of NECR, the simulated peak NECR was 216.8 kcps at 17.40 kBq/ml for 18 F and 207.1 kcps at 20.10 kBq/ml for 68 Ga compared to the measured peak NECR of 216.8 kcps at 18.60 kBq/ml and 205.6 kcps at 20.40 kBq/ml for 18 F and 68 Ga, respectively. For 11 C, 13 N, and 15 O, results confirmed a peak NECR similar to 18 F with the effective activity concentration scaled by the inverse of the positron fraction. For 82 Rb, and 68 Ga, the peak NECR was lower than for 18 F while the corresponding activity concentrations were higher. For the higher energy positron emitters, the positron range was confirmed to be

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PET iterative reconstruction incorporating an efficient positron range correction method

Cited by 36 publications

References 22 publications

Quantitative performance and optimal regularization parameter in block sequential regularized expectation maximization reconstructions in clinical 68Ga-PSMA PET/MR

Quantitative performance and optimal regularization parameter in block sequential regularized expectation maximization reconstructions in clinical 68Ga-PSMA PET/MR

Comparative study of alternative Geant4 hadronic ion inelastic physics models for prediction of positron-emitting radionuclide production in carbon and oxygen ion therapy

Monte Carlo Simulations of the GE Signa PET/MR for Different Radioisotopes

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