Browsing by Author "Reilhac-Laborde, A"

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    Framework for the construction of a Monte Carlo simulated brain PET–MR image database
    (Elsevier, 2014-01-11) Thomas, BA; Erlandsson, K; Drobnjak, I; Pedemonte, S; Vunckx, K; Bousse, A; Reilhac-Laborde, A; Ourselin, S; Hutton, BF
    Simultaneous PET–MR acquisition reduces the possibility of registration mismatch between the two modalities. This facilitates the application of techniques, either during reconstruction or post-reconstruction, that aim to improve the PET resolution by utilising structural information provided by MR. However, in order to validate such methods for brain PET–MR studies it is desirable to evaluate the performance using data where the ground truth is known. In this work, we present a framework for the production of datasets where simulations of both the PET and MR, based on real data, are generated such that reconstruction and post-reconstruction approaches can be fairly compared. © 2013 Elsevier B.V.
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    Quantification of dopamine d2 receptor density and apparent affinity can be used to longitudinally assess transient striatal variations during adolescence using [11c]raclopride pet imaging
    (John Wiley & Sons, Inc., 2017-04-11) Callaghan, PD; Sobbi, PF; Safavi-Naeini, M; Wimberley, CA; Davis, E; Zahra, D; Arthur, A; Rahardjo, GL; Perkins, G; Pascali, G; Reilhac-Laborde, A; Grégoire, MC
    Background Transient increases in striatal dopamine D2 receptors occur during adolescence in rats, correlating with a developmental epoch where synaptic pruning occurs. Alteration of these processes with external stresses during adolescence may lead to affective disorders later in life. Longitudinal PET imaging with [11C]raclopride using a partial saturation design allows assessment of density (Bavail) and affinity changes (appKd) to map neurodevelopmental changes in D2 expression, which necessitates a significant level of receptors occupancy during the PET study. Aims Validate that repeated transient partial saturation of D2 receptors does not bias measures of D2 Bavail and appKd assessed using PET/CT imaging with [11C]raclopride. Methods Three cohorts of male Sprague-Dawley rats (n=6-7/group) underwent a single session of PET/CT imaging (INVEON, Siemens, USA) with [11C]raclopride (5 nmol injected i.v.) as naïve or after repeated partial saturation of D2 receptors: Cohort A received 5nmol raclopride (i.v) weekly from PND35 (postnatal day) to PND96 with PET imaging session at PND96, cohort B was scanned at PND96; Cohort C was scanned at PND35 Datasets were reconstructed (2D-FBP), coregistered with CT and time-activity data extracted using age matched atlas-based volumes of interest (striatum, cerebellum). in vivo receptor density and appKd were derived using kinetic modelling (comparisons used 1-way ANOVA follow by post hoc test). Results Expected differences in Bavail and appKd were seen between the adolescent (PND35) and the adult (PND96) cohorts, corresponding with increases in D2 receptor consistently reported in the literature using post mortem methods. No significant difference was observed in both Bavail and appKd in cohort A, exposed to repeated D2 partial saturation, compared to the naïve cohort B. Conclusion Longitudinal quantification of dopamine D2 receptor density and apparent affinity in vivo using [11C]raclopride PET imaging with partial saturation can be used to map changes in adolescent and adult rats.
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    What approach to brain partial volume correction is best for PET/MRI?
    (Elsevier B.V., 2013-02-21) Hutton, BF; Thomas, BA; Erlandsson, K; Bousse, A; Reilhac-Laborde, A; Kazantsev, D; Pedemonte, S; Vunckx, K; Arridge, SR; Ourselin, S
    Many partial volume correction approaches make use of anatomical information, readily available in PET/MRI systems but it is not clear what approach is best. Seven novel approaches to partial volume correction were evaluated, including several post-reconstruction methods and several reconstruction methods that incorporate anatomical information. These were compared with an MRI-independent approach (reblurred van Cittert ) and uncorrected data. Monte Carlo PET data were generated for activity distributions representing both 18F FDG and amyloid tracer uptake. Post-reconstruction methods provided the best recovery with ideal segmentation but were particularly sensitive to mis-registration. Alternative approaches performed better in maintaining lesion contrast (unseen in MRI) with good noise control. These were also relatively insensitive to mis-registration errors. The choice of method will depend on the specific application and reliability of segmentation and registration algorithms. (c) 2012 Elsevier Science B.V.