Browsing by Author "Reilhac, A"
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- Item4D PET iterative deconvolution with spatiotemporal regularization for quantitative dynamic PET imaging(Elsevier, 2015-09-01) Reilhac, A; Charil, A; Wimberley, CA; Angelis, GI; Hamze, H; Callaghan, PD; Garcia, MP; Boisson, F; Ryder, W; Meikle, SR; Grégoire, MCQuantitative measurements in dynamic PET imaging are usually limited by the poor counting statistics particularly in short dynamic frames and by the low spatial resolution of the detection system, resulting in partial volume effects (PVEs). In this work, we present a fast and easy to implement method for the restoration of dynamic PET images that have suffered from both PVE and noise degradation. It is based on a weighted least squares iterative deconvolution approach of the dynamic PET image with spatial and temporal regularization. Using simulated dynamic [11C] Raclopride PET data with controlled biological variations in the striata between scans, we showed that the restoration method provides images which exhibit less noise and better contrast between emitting structures than the original images. In addition, the method is able to recover the true time activity curve in the striata region with an error below 3% while it was underestimated by more than 20% without correction. As a result, the method improves the accuracy and reduces the variability of the kinetic parameter estimates calculated from the corrected images. More importantly it increases the accuracy (from less than 66% to more than 95%) of measured biological variations as well as their statistical detectivity. © 2015 Elsevier Inc.
- ItemAnalysis of variance in neuroreceptor ligand imaging studies(Public Library of Science, 2011-08-17) Ko, JH; Reilhac, A; Ray, N; Rusjan, P; Bloomfield, P; Pellecchia, G; Houle, S; Strafella, A PRadioligand positron emission tomography (PET) with dual scan paradigms can provide valuable insight into changes in synaptic neurotransmitter concentration due to experimental manipulation. The residual t-test has been utilized to improve the sensitivity of the t-test in PET studies. However, no further development of statistical tests using residuals has been proposed so far to be applied in cases when there are more than two conditions. Here, we propose the residual f-test, a one-way analysis of variance (ANOVA), and examine its feasibility using simulated [(11)C] raclopride PET data. We also re-visit data from our previously published [(11)C] raclopride PET study, in which 10 individuals underwent three PET scans under different conditions. We found that the residual f-test is superior in terms of sensitivity than the conventional f-test while still controlling for type 1 error. The test will therefore allow us to reliably test hypotheses in the smaller sample sizes often used in explorative PET studies. © 2011, Public Library of Science.
- ItemAnalytical positron range modelling in heterogeneous media for PET Monte Carlo simulation(IOP Publishing Ltd, 2011-06-07) Lehnert, W; Grégoire, MC; Reilhac, A; Meikle, SRMonte Carlo simulation codes that model positron interactions along their tortuous path are expected to be accurate but are usually slow. A simpler and potentially faster approach is to model positron range from analytical annihilation density distributions. The aims of this paper were to efficiently implement and validate such a method, with the addition of medium heterogeneity representing a further challenge. The analytical positron range model was evaluated by comparing annihilation density distributions with those produced by the Monte Carlo simulator GATE and by quantitatively analysing the final reconstructed images of Monte Carlo simulated data. In addition, the influence of positronium formation on positron range and hence on the performance of Monte Carlo simulation was investigated. The results demonstrate that 1D annihilation density distributions for different isotope–media combinations can be fitted with Gaussian functions and hence be described by simple look-up-tables of fitting coefficients. Together with the method developed for simulating positron range in heterogeneous media, this allows for efficient modelling of positron range in Monte Carlo simulation. The level of agreement of the analytical model with GATE depends somewhat on the simulated scanner and the particular research task, but appears to be suitable for lower energy positron emitters, such as 18F or 11C. No reliable conclusion about the influence of positronium formation on positron range and simulation accuracy could be drawn. © 2011 IOP Publishing LTD
- ItemAssessment of a fast generated analytical matrix for rotating slat collimation iterative reconstruction: a possible method to optimize the collimation profile(IOP Science, 2015-02-26) Boisson, F; Bekaert, V; Reilhac, A; Wurtz, J; Brasse, DA polystyrene film spun onto polished silicon substrates was implanted with argon ions using plasma immersion ion implantation (PIII) to activate its surface for single-step immobilization of biological molecules. The film was subsequently investigated by X-ray and neutron reflectometry, ultraviolet (UV)–visible (vis) and Fourier transform infrared (FTIR) ellipsometry, FTIR and Raman spectroscopy, as well as nuclear reaction analysis to determine the structural and compositional transformations associated with the surface activation. The ion irradiation resulted in a significant densification of the carbon structure, which was accompanied by hydrogen loss. The density and hydrogen profiles in the modified surface layers were found to agree with the expected depths of ion implantation as calculated by the Stopping and Range of Ions in Matter (SRIM) software. The data demonstrate that the reduction in film thickness is due to ion-induced densification rather than the removal of material by etching. Characterization by FTIR, atomic force microscopy (AFM), ellipsometry, and X-ray reflectometry shows that polystyrene films modified in this way immobilize dense layers of protein (tropoelastin) directly from solution. A substantial fraction of the immobilized protein layer remains after rigorous washing with sodium dodecyl sulfate solution, indicating that its immobilization is by covalent bonding. © Copyright 2020 IOP Publishing
- ItemCharacterisation of partial volume effect and region-based correction in small animal positron emission tomography (PET) of the rat brain(Elsevier Inc, 2012-05-01) Lehnert, W; Grégoire, MC; Reilhac, A; Meikle, SRAccurate quantification of PET imaging data is required for a useful interpretation of the measured radioactive tracer concentrations. The partial volume effect (PVE) describes signal dilution and mixing due to spatial resolution and sampling limitations, which introduces bias in quantitative results. In the present study we investigated the magnitude of PVE for volumes of interest (VOIs) in the rat brain and the effect of positron range. In simulated 11C-raclopride studies we examined the influence of PVE on time activity curves in striatal and cerebellar VOIs and binding potential estimation. The performance of partial volume correction (PVC) was studied using the region-based geometric transfer matrix (GTM) method including the question of whether a spatially variant point spread function (PSF) is necessary for PVC of a rat brain close to the centre of the field of view. Furthermore, we determined the effect of spillover from activity outside the brain. The results confirmed that PVE is significant in rat brain PET and showed that positron range is an important factor that needs to be included in the PSF. There was considerable bias in time activity curves for the simulated 11C-raclopride studies and significant underestimation of binding potential even for very small centred VOIs. Good activity recovery was achieved with the GTM PVC using a spatially invariant simulated PSF when no activity was present outside the brain. PVC using a simple Gaussian fit point spread function was not sufficiently accurate. Spillover from regions outside the brain had a significant impact on measured activity concentrations and reduced the accuracy of PVC with the GTM method using rat brain regions alone, except for the smallest VOI size but at the cost of increased noise. Voxel-based partial volume correction methods which inherently compensate for spillover from outside the brain might be a more suitable choice. © 2012 Elsevier Inc.
- ItemA data driven method for estimation of Bavail and appKD using a single injection protocol with [11C]raclopride in the mouse(Elsevier Inc., 2014-10-01) Wimberley, CA; Fischer, K; Reilhac, A; Pichler, BJ; Grégoire, MCPurpose The partial saturation approach (PSA) is a simple, single injection experimental protocol that will estimate both Bavail and appKD without the use of blood sampling. This makes it ideal for use in longitudinal studies of neurodegenerative diseases in the rodent. The aim of this study was to increase the range and applicability of the PSA by developing a data driven strategy for determining reliable regional estimates of receptor density (Bavail) and in vivo affinity (1/appKD), and validate the strategy using a simulation model. Methods The data driven method uses a time window guided by the dynamic equilibrium state of the system as opposed to using a static time window. To test the method, simulations of partial saturation experiments were generated and validated against experimental data. The experimental conditions simulated included a range of receptor occupancy levels and three different Bavail and appKD values to mimic diseases states. Also the effect of using a reference region and typical PET noise on the stability and accuracy of the estimates was investigated. Results The investigations showed that the parameter estimates in a simulated healthy mouse, using the data driven method were within 10±30% of the simulated input for the range of occupancy levels simulated. Throughout all experimental conditions simulated, the accuracy and robustness of the estimates using the data driven method were much improved upon the typical method of using a static time window, especially at low receptor occupancy levels. Introducing a reference region caused a bias of approximately 10% over the range of occupancy levels. Conclusions Based on extensive simulated experimental conditions, it was shown the data driven method provides accurate and precise estimates of Bavail and appKD for a broader range of conditions compared to the original method. © 2014 Elsevier Inc.
- ItemDetermining glucose metabolism kineticsuUsing 18F-FDG micro-PET/CT(MyJoVE Corporation., 2017-05-02) Cochran, BJ; Ryder, WJ; Parmar, A; Klaeser, K; Reilhac, A; Angelis, GI; Meikle, SR; Barter, PJ; Rye, KAThis paper describes the use of 18F-FDG and micro-PET/CT imaging to determine in vivo glucose metabolism kinetics in mice (and is transferable to rats). Impaired uptake and metabolism of glucose in multiple organ systems due to insulin resistance is a hallmark of type 2 diabetes. The ability of this technique to extract an image-derived input function from the vena cava using an iterative deconvolution method eliminates the requirement of the collection of arterial blood samples. Fitting of tissue and vena cava time activity curves to a two-tissue, three compartment model permits the estimation of kinetic micro-parameters related to the 18F-FDG uptake from the plasma to the intracellular space, the rate of transport from intracellular space to plasma and the rate of 18F-FDG phosphorylation. This methodology allows for multiple measures of glucose uptake and metabolism kinetics in the context of longitudinal studies and also provides insights into the efficacy of therapeutic interventions. © 2022 MyJoVE Corporation
- ItemEvaluation of three MRI-based anatomical priors for quantitative PET brain imaging(Institute of Electrical and Electronics Engineers, 2012-03-01) Vunckx, K; Atre, A; Baete, K; Reilhac, A; Deroose, CM; Van Laere, K; Nuyts, JIn emission tomography, image reconstruction and therefore also tracer development and diagnosis may benefit from the use of anatomical side information obtained with other imaging modalities in the same subject, as it helps to correct for the partial volume effect. One way to implement this, is to use the anatomical image for defining the a priori distribution in a maximum-a-posteriori (MAP) reconstruction algorithm. In this contribution, we use the PET-SORTEO Monte Carlo simulator to evaluate the quantitative accuracy reached by three different anatomical priors when reconstructing positron emission tomography (PET) brain images, using volumetric magnetic resonance imaging (MRI) to provide the anatomical information. The priors are: 1) a prior especially developed for FDG PET brain imaging, which relies on a segmentation of the MR-image (Baete , 2004); 2) the joint entropy-prior (Nuyts, 2007); 3) a prior that encourages smoothness within a position dependent neighborhood, computed from the MR-image. The latter prior was recently proposed by our group in (Vunckx and Nuyts, 2010), and was based on the prior presented by Bowsher (2004). The two latter priors do not rely on an explicit segmentation, which makes them more generally applicable than a segmentation-based prior. All three priors produced a compromise between noise and bias that was clearly better than that obtained with postsmoothed maximum likelihood expectation maximization (MLEM) or MAP with a relative difference prior. The performance of the joint entropy prior was slightly worse than that of the other two priors. The performance of the segmentation-based prior is quite sensitive to the accuracy of the segmentation. In contrast to the joint entropy-prior, the Bowsher-prior is easily tuned and does not suffer from convergence problems. © 2012, IEEE
- ItemImaging capabilities of the Inveon SPECT system using single-and multipinhole collimators(Society of Nuclear Medicine and Molecular Imaging, 2013-09-05) Boisson, F; Zahra, D; Parmar, A; Grégoire, MC; Meikle, SR; Hamze, H; Reilhac, AThe Inveon small-animal SPECT system comes with several types of multipinhole collimator plates. We evaluate here the performance measurements of the Inveon SPECT system using 6 different collimators: 3 dedicated for mouse imaging and 3 for rat imaging. Methods: The measured performance parameters include the sensitivity, the spatial resolution using line sources, the ultra-micro Derenzo phantom, the recovery coefficient and the noise measurements using the National Electrical Manufacturers Association NU-4 image quality phantom, obtained with the 2 reconstruction algorithms available with the Inveon Acquisition Workplace, version 1.5—the 3-dimensional ordered-subset expectation maximization (3DOSEM) and the 3-dimensional maximum a posteriori (3DMAP). Further, the overall performance of the system is illustrated by an animal experiment. Results: The results show that the Inveon SPECT scanner offers a spatial resolution, measured at the center of the field of view, ranging from 0.6 to 1 mm with the collimator plates dedicated to mouse imaging and from 1.2 to less than 2 mm with rat collimator plates. The system sensitivity varies from 29 to 404 cps/MBq for mouse collimators and from 53 to 175 cps/MBq for rat collimators. The image quality study showed that 3DMAP allows better noise reduction while preserving the recovery coefficient, compared with other regularization strategies such as the premature termination of the 3DOSEM reconstruction or 3DOSEM followed by gaussian filtering. Conclusion: The acquisition parameters, such as the collimator set and the radius of rotation, offer a wide range of possibilities to apply to a large number of biologic studies. However, special care must be taken because this increase in sensitivity can be offset by image degradation, such as image artifacts caused by projection overlap and statistical noise due to a higher number of iterations required for convergence. 3DMAP allowed better noise reduction while maintaining relatively constant recovery coefficients, as compared with other reconstruction strategies. © 2013 by the Society of Nuclear Medicine and Molecular Imaging, Inc.
- ItemIn vivo PET imaging with [18F]FDG to explain improved glucose uptake in an apolipoprotein A-I treated mouse model of diabetes(Springer Nature, 2016-05-18) Cochran, BJ; Ryder, WJ; Parmar, A; Tang, S; Reilhac, A; Arthur, A; Charil, A; Hamze, H; Barter, PJ; Kritharides, L; Meikle, SR; Grégoire, MC; Rye, KAType 2 diabetes is characterised by decreased HDL levels, as well as the level of apolipoprotein A-I (apoA-I), the main apolipoprotein of HDLs. Pharmacological elevation of HDL and apoA-I levels is associated with improved glycaemic control in patients with type 2 diabetes. This is partly due to improved glucose uptake in skeletal muscle.© 2016 Springer Nature
- ItemNEMA NU 4-2008 validation and applications of the PET-SORTEO Monte Carlo simulations platform for the geometry of the Inveon PET preclinical scanner(IOP Publishing, 2013-09-10) Boisson, F; Wimberley, CA; Lehnert, W; Zahra, D; Pham, TQ; Perkins, G; Hamze, H; Grégoire, MC; Reilhac, AMonte Carlo-based simulation of positron emission tomography (PET) data plays a key role in the design and optimization of data correction and processing methods. Our first aim was to adapt and configure the PET-SORTEO Monte Carlo simulation program for the geometry of the widely distributed Inveon PET preclinical scanner manufactured by Siemens Preclinical Solutions. The validation was carried out against actual measurements performed on the Inveon PET scanner at the Australian Nuclear Science and Technology Organisation in Australia and at the Brain and Mind Research Institute and by strictly following the NEMA NU 4-2008 standard. The comparison of simulated and experimental performance measurements included spatial resolution, sensitivity, scatter fraction and count rates, image quality and Derenzo phantom studies. Results showed that PET-SORTEO reliably reproduces the performances of this Inveon preclinical system. In addition, imaging studies showed that the PET-SORTEO simulation program provides raw data for the Inveon scanner that can be fully corrected and reconstructed using the same programs as for the actual data. All correction techniques (attenuation, scatter, randoms, dead-time, and normalization) can be applied on the simulated data leading to fully quantitative reconstructed images. In the second part of the study, we demonstrated its ability to generate fast and realistic biological studies. PET-SORTEO is a workable and reliable tool that can be used, in a classical way, to validate and/or optimize a single PET data processing step such as a reconstruction method. However, we demonstrated that by combining a realistic simulated biological study ([11C]Raclopride here) involving different condition groups, simulation allows one also to assess and optimize the data correction, reconstruction and data processing line flow as a whole, specifically for each biological study, which is our ultimate intent. © 2017 IOP Publishing
- ItemOptimisation of PET data processing for a single injection experiment with [11C]Raclopride using a simulations based approach(Society of Nuclear Medicine, 2014-11-05) Wimberley, CA; Angelis, GI; Boisson, F; Callaghan, PD; Fischer, K; Pichler, BJ; Meikle, SR; Grégoire, MC; Reilhac, AObjectives Positron emission tomography (PET) with [11C]Raclopride is an important tool for studying dopamine D2 receptor expression in vivo. [11C]Raclopride PET binding experiments conducted using the Partial Saturation Approach (PSA) (a simple, single injection experiment, Delforge 1995) allow the estimation of receptor density (Bavail) and the in vivo affinity 1/(KD). To achieve accurate and stable parameter estimates, and the ability to detect small changes in these parameters, the impact of the data processing chain should be investigated and optimised. Methods Two groups of PET scans were generated for a Partial Saturation Approach (PSA) experiment using Monte Carlo simulation software with a biological phenomenon inferred between the groups. The kinetic parameters Bavail and KD were estimated and the impact of spatial smoothing, temporal denoising and image resolution recovery on the statistical detectability of change in the estimates was investigated. Results Before optimisation, the inferred Bavail difference between the two groups was underestimated by 42% and detected in 66% of cases (at p<0.05), while a false decrease of KD by 13% was detected in more than 11% of cases. After optimisation, the calculated Bavail difference was underestimated by only 3.7% and detected in 89% of cases, while a false slight increase of KD by 3.7 % was detected in only 2% of cases. Conclusions The use of Monte Carlo generated PET scans allowed the optimisation of the data processing chain in order to reliably estimate and detect changes in the parameters Bavail and KD.
- ItemOSSI-PET: open-access database of simulated [11C]raclopride scans for the inveon preclinical PET scanner: application to the optimization of reconstruction methods for dynamic studies(IEEE, 2016-07) Garcia, MP; Charil, A; Callaghan, PD; Wimberley, CA; Busso, F; Grégoire, MC; Bardiès, M; Reilhac, AA wide range of medical imaging applications benefits from the availability of realistic ground truth data. In the case of positron emission tomography (PET), ground truth data is crucial to validate processing algorithms and assessing their performances. The design of such ground truth data often relies on Monte-Carlo simulation techniques. Since the creation of a large dataset is not trivial both in terms of computing time and realism, we propose the OSSI-PET database containing 350 simulated [ 11 C]Raclopride dynamic scans for rats, created specifically for the Inveon pre-clinical PET scanner. The originality of this database lies on the availability of several groups of scans with controlled biological variations in the striata. Besides, each group consists of a large number of realizations (i.e., noise replicates). We present the construction methodology of this database using rat pharmacokinetic and anatomical models. A first application using the OSSI-PET database is presented. Several commonly used reconstruction techniques were compared in terms of image quality, accuracy and variability of the activity estimates and of the computed kinetic parameters. The results showed that OP-OSEM3D iterative reconstruction method outperformed the other tested methods. Analytical methods such as FBP2D and 3DRP also produced satisfactory results. However, FORE followed by OSEM2D reconstructions should be avoided. Beyond the illustration of the potential of the database, this application will help scientists to understand the different sources of noise and bias that can occur at the different steps in the processing and will be very useful for choosing appropriate reconstruction methods and parameters. © 2016 IEEE
- ItemPeformance evaluation of preclinical PET scanners with the NEMA NU-4 image quality phantom using a collection of radioisotopes(John Wiley & Sons, Inc., 2013-04-13) Nezich, R; Reilhac, A; Zahra, D; Price, RBackground: The radioisotopes 18F, 11C, 124I, 68Ga, 89Zr and 64Cu have found numerous applications in small animal PET imaging, and this entire subset of isotopes will soon be available to Australian preclinical researchers. The suitability of an isotope for a given imaging application is determined largely by its radioactive half-life. However, other characteristic physical properties of the isotope such as the branching fraction and positron energy can severely impact image quality and the ability to accurately quantify uptake of the radio-labelled molecule. Furthermore, the specific acquisition parameters and reconstruction algorithms employed to generate the image can significantly affect the image quality and quantification accuracy. The NEMA NU-4 2008 standards describe a method to evaluate the performance of small animal PET scanners. The information gathered through the NEMA Image Quality phantom scanning experiment is valuable for optimising the scanner usage, because it allows for the best selection of acquisition/reconstruction protocols and provides knowledge of the resolution limits of the system. Method: NEMA NU-4 image quality phantom performance testing was performed on the Siemens Inveon with 18F, 124I and 64Cu, using default acquisition parameters and each of the available reconstruction algorithms. Further testing will be performed using 11C, 68Ga and 89Zr. The Bioscan NanoPET scanner will be tested with all of the mentioned isotopes. Results: The figure shows NU-4 phantom images obtained for 18F, 64Cu and 124I; using the Inveon preclinical scanner and FBP2D reconstruction. The relatively poor image quality obtained with 124I is mainly caused by single gamma-photon contamination. Due to a higher positron range, recovery coefficients obtained with 124I are well below the values measured with 18F. Conclusion: NEMA NU-4 performance testing provides valuable information about the image quality achievable for a given PET scanner and radioisotope. © 2003 John Wiley & Sons, Inc.
- ItemSimulation-based optimisation of the PET data processing for partial saturation approach protocols(Elsevier B.V., 2014-08-15) Wimberley, CA; Angelis, GI; Boisson, F; Callaghan, PD; Fischer, K; Pichler, BJ; Meikle, SR; Grégoire, MC; Reilhac, APositron emission tomography (PET) with [11C]Raclopride is an important tool for studying dopamine D2 receptor expression in vivo. [11C]Raclopride PET binding experiments conducted using the Partial Saturation Approach (PSA) allow the estimation of receptor density (Bavail) and the in vivo affinity appKD. The PSA is a simple, single injection, single scan experimental protocol that does not require blood sampling, making it ideal for use in longitudinal studies. In this work, we generated a complete Monte Carlo simulated PET study involving two groups of scans, in between which a biological phenomenon was inferred (a 30% decrease of Bavail), and used it in order to design an optimal data processing chain for the parameter estimation from PSA data. The impact of spatial smoothing, noise removal and image resolution recovery technique on the statistical detection was investigated in depth. We found that image resolution recovery using iterative deconvolution of the image with the system point spread function associated with temporal data denoising greatly improves the accuracy and the statistical reliability of detecting the imposed phenomenon. Before optimisation, the inferred Bavail variation between the two groups was underestimated by 42% and detected in 66% of cases, while a false decrease of appKD by 13% was detected in more than 11% of cases. After optimisation, the calculated Bavail variation was underestimated by only 3.7% and detected in 89% of cases, while a false slight increase of appKD by 3.7% was detected in only 2% of cases. We found during this investigation that it was essential to adjust a factor that accounts for difference in magnitude between the non-displaceable ligand concentrations measured in the target and in the reference regions, for different data processing pathways as this ratio was affected by different image resolutions. © 2014 Elsevier B.V..
- ItemSimultaneous scanning of two mice in a small-animal PET scanner: a simulation-based assessment of the signal degradation(IOP science publishing, 2016-01-21) Reilhac, A; Boisson, F; Wimberley, CA; Parmar, A; Zahra, D; Hamze, H; Davis, E; Arthur, A; Bouillot, C; Charil, A; Grégoire, MCIn PET imaging, research groups have recently proposed different experimental set ups allowing multiple animals to be simultaneously imaged in a scanner in order to reduce the costs and increase the throughput. In those studies, the technical feasibility was demonstrated and the signal degradation caused by additional mice in the FOV characterized, however, the impact of the signal degradation on the outcome of a PET study has not yet been studied. Here we thoroughly investigated, using Monte Carlo simulated [18F]FDG and [11C]Raclopride PET studies, different experimental designs for whole-body and brain acquisitions of two mice and assessed the actual impact on the detection of biological variations as compared to a single-mouse setting. First, we extended the validation of the PET-SORTEO Monte Carlo simulation platform for the simultaneous simulation of two animals. Then, we designed [18F]FDG and [11C]Raclopride input mouse models for the simulation of realistic whole-body and brain PET studies. Simulated studies allowed us to accurately estimate the differences in detection between single- and dual-mode acquisition settings that are purely the result of having two animals in the FOV. Validation results showed that PET-SORTEO accurately reproduced the spatial resolution and noise degradations that were observed with actual dual phantom experiments. The simulated [18F]FDG whole-body study showed that the resolution loss due to the off-center positioning of the mice was the biggest contributing factor in signal degradation at the pixel level and a minimal inter-animal distance as well as the use of reconstruction methods with resolution modeling should be preferred. Dual mode acquisition did not have a major impact on ROI-based analysis except in situations where uptake values in organs from the same subject were compared. The simulated [11C]Raclopride study however showed that dual-mice imaging strongly reduced the sensitivity to variations when mice were positioned side-by-side while no sensitivity reduction was observed when they were facing each other. This is the first study showing the impact of different experimental designs for whole-body and brain acquisitions of two mice on the quality of the results using Monte Carlo simulated [18F]FDG and [11C]Raclopride PET studies. © 2016 Institute of Physics and Engineering in Medicine
- ItemTest-retest reliability and inter scanner variability of 11C-raclopride striatal binding potentials between two INVEON PET/CT imaging systems for naïve Sprague Dawley rats(Wiley, 2014-04-16) Callaghan, PD; Zahra, D; Wimberley, CA; Arthur, A; Rahardjo, GL; Hamze, H; Davis, E; Nguyen, A; Boisson, F; Perkins, G; Pascali, G; Reilhac, A; Grégoire, MCBackground: 11C-raclopride is a routine tracer for quantification of dopamine D2 receptors in neurological and psychiatric disease. D2 imaging in key longitudinal models has significant utility of understanding mechanisms and therapeutic interventions. Aims: Optimisation of preclinical imaging and data analysis protocols for 11C-raclopride in rat brain. Methods: a) Test-retest reliability: Naïve male Sprague Dawley rats (n = 6) underwent test-retest assessment of binding potential variability, with two scans, 1 week apart. Rats were anaesthetised (1–5% isoflurane) and received 11C-raclopride (>0.1 nmol, 20–40 MBq) during 1 hour image acquisition (Siemens Inveon PET/CT), followed by a 10 minute CT scan. b) Assessment of the intersystem variability of the INVEON scanners (n = 12). Test-retest experiments were performed on a second INVEON system. c) Assessment of inter system variability with arterial blood sampling (n = 5). Acquisitions were performed (as above) with prior femoral artery cannulation: 23 blood samples (∼30 ul) were collected during PET acquisition, and plasma metabolite corrected input functions generated. PET list mode data were histogrammed (23 frames) and reconstructed with 2D filtered backprojection algorithm. The impact of some post-reconstruction image processing techniques, such iterative deconvolution of the image and data denoising techniques, onto the accuracy and reliability of the computed parameter of interest were also investigated. Binding potential parametric maps were calculated from the dynamic PET data (using either a standard reference tissue modelling using the cerebellum TAC (test-retest), and or a 2 compartment kinetic modelling with input function). Preliminary results: Significant improvements were seen for tissue activity data after denoising /iterative deconvolution (see figure). Analysis of binding potential data are currently in progress. Conclusion: Assessment of within and intersystem variability will aid the appropriate statistical design of future longitudinal 11C-raclopride imaging studies. Improvements from post-reconstruction image processing techniques show significant benefits. © 1999-2022 John Wiley & Sons, Inc.