Reproducibility of PET Activation Studies: Lessons from a Multi-Center European Experiment (original) (raw)
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Influence of ANOVA Design and Anatomical Standardization on Statistical Mapping for PET Activation
NeuroImage, 1998
We have created images of z value, error, and variation components for a PET activation study using various ANOVA designs and anatomical standardization methods. Data were acquired in four PET centers. In each center, CBF was measured on six normal male subjects under resting and covert verb generation, three times for each. The images were anatomically standardized with LINEAR transformation, SPM (Ver. 95), HBA (Karolinska/Tohoku), or MICHIGAN (Minoshima). ANOVA was performed pixel by pixel to compute t (and z) for the task main effect (Verb vs Rest) in four different designs: (i) two way (subject and task) (2W), (ii) two-way with interaction (2WI), (iii) subject considered a random factor (2WI-MX), and (iv) threeway (subject, task, and replication) (3W). A large area extending from the Broca to the left premotor cortex was activated. The localization of the highest peak depended both on the anatomical standardization and on the ANOVA design, the variation ranging 3-4 cm.
Effects of Timing and Duration of Cognitive Activation in [15O]water PET Studies
Journal of Cerebral Blood Flow & Metabolism, 1994
The multiple injection [150]water method of fers unique opportunities for studying cognitive process ing by the human brain. The influence of the duration and temporal placement of an activation task, in relation to the arrival of the radiotracer in the brain, is a fundamental methodologic question for cognitive activation studies. A quantitative positron emission tomography (PET) study of five normal volunteers was performed in which the stimulation consisted of a visual activation task (alternat ing checkerboard pattern) superimposed on an auditory baseline task (syllable monitoring). Ten injection condi tions, with varying duration and timing of the visual ac tivation, were used. Regional CBF (rCBF) in visual cor tex was measured quantitatively using the autoradio graphic method. A 20-s stimulation, centered on the bolus Numerous studies over the past decade have demonstrated the power of the multiple injection [ISO]water positron emission tomography (PET) technique to map cognitive operations in the human brain (Raichle et aI.
Statistical parametric mapping (SPM) is now considered the gold standard both in clinical and research neuroimaging investigations. We investigate the feasibility of Monte Carlo simulations-based assessment of the sensitivity and specificity of SPM analysis in Positron Emission Tomography (PET) neuroactivation studies with respect to design parameters such as study size, activation/lesion localisation, intensity and size. Fifteen data sets were generated for different foci activation levels, and localizations using five spheres located within the digital Hoffman 3D brain phantom with diameters corresponding to 6 and 8 mm, close to the resolution limit of the ECAT ART PET scanner (CTI/Siemens). The five foci were defined in the thalamus (T), putamen (P), cingulate gyrus (CG), right frontal cortex (RFC) and the right supramarginal gyrus (RSG) covering different structures of particular interest in cognitive neuroscience. In addition, we carried out a coordinate search of the resulting...
Optimization of brain PET imaging for a multicentre trial: the French CATI experience
EJNMMI physics, 2016
CATI is a French initiative launched in 2010 to handle the neuroimaging of a large cohort of subjects recruited for an Alzheimer's research program called MEMENTO. This paper presents our test protocol and results obtained for the 22 PET centres (overall 13 different scanners) involved in the MEMENTO cohort. We determined acquisition parameters using phantom experiments prior to patient studies, with the aim of optimizing PET quantitative values to the highest possible per site, while reducing, if possible, variability across centres. Jaszczak's and 3D-Hoffman's phantom measurements were used to assess image spatial resolution (ISR), recovery coefficients (RC) in hot and cold spheres, and signal-to-noise ratio (SNR). For each centre, the optimal reconstruction parameters were chosen as those maximizing ISR and RC without a noticeable decrease in SNR. Point-spread-function (PSF) modelling reconstructions were discarded. The three figures of merit extracted from the images...
Journal of Cerebral Blood Flow & Metabolism, 2020
It is a growing concern that outcomes of neuroimaging studies often cannot be replicated. To counteract this, the magnetic resonance (MR) neuroimaging community has promoted acquisition standards and created data sharing platforms, based on a consensus on how to organize and share MR neuroimaging data. Here, we take a similar approach to positron emission tomography (PET) data. To facilitate comparison of findings across studies, we first recommend publication standards for tracer characteristics, image acquisition, image preprocessing, and outcome estimation for PET neuroimaging data. The co-authors of this paper, representing more than 25 PET centers worldwide, voted to classify information as mandatory, recommended, or optional. Second, we describe a framework to facilitate data archiving and data sharing within and across centers. Because of the high cost of PET neuroimaging studies, sample sizes tend to be small and relatively few sites worldwide have the required multidiscipli...
Introduction. Functional neuroimaging of the brain is a widely used method to study cognitive functions. Aim. The aim of this study was to compare the activity of the brain during performance of the tasks of phonemic and semantic fluency with the paced-overt technique in terms of prolonged activation of the brain. Methods. The study included 17 patients aged 20–40 years who were treated in the past for Hodgkin's lymphoma, now in remission. Due to the type of task, the subjects were divided into two groups. Nine people performed the phonemic fluency task, and eight semantic. Due to the disease, all subjects were subject to neuropsychological diagnosis. The diagnosis of any cognitive impairment was an exclusion criterion. Neuroimaging was performed using PET technique with 18F-fluorodeoxyglucose (FDG) tracer. Results. Performance of a verbal fluency test, regardless of the version of the task, was associated with greater activity of the left hemisphere of the brain. The most involved areas compared with other areas of key importance for the performance of verbal fluency tasks were frontal lobes. An increased activity of parietal structures was also shown. Conclusions. The study did not reveal differences in brain activity depending on the type of task. Performing the test in both phonemic and semantic form for a long time, in terms
NeuroImage, 1996
In a functional imaging study of cued paired associate retrieval, in which the strength of association between pair members was systematically varied, we predicted increased right frontal activity as a function of weakening semantic linkage. An initial univariate analysis found the opposite effect, with greater right frontal activity during recall of strongly linked paired associates. This unexpected result led us to perform a multivariate analysis of covariance (MANCOVA), an approach which proved more informative. This analysis showed that the most significant source of taskrelated variance was accounted for by a nonlinear relationship not predicted by the prior hypothesis and not revealed by the standard univariate approach. This application of the MANCOVA supports the assertion that multivariate analysis can provide an important adjunct to univariate approaches like statistical parametric mapping (SPM). New perspectives engendered by the MANCOVA still allow for statistical inference but are not constrained by explicit hypotheses about specific task-dependent effects.