AbstractsBiology & Animal Science

Currently, positron emission tomography (PET) produces reconstructed images, e.g. of a brain, that require considerable post-processing efforts, in order to deliver meaningful results to researchers. This work proposes to alleviate these post-processing efforts by incorporating each step within the reconstruction framework of the raw PET data to provide the researchers directly with better images of interest, in a stereotaxic space for easy interpretation.In neuroscience and psychiatry, the goal of many studies using PET is to assess whether or not specific biological parameters significantly differ between groups, e.g. healthy controls vs. a patient group, or conditions, e.g. placebo vs. treatment. However, to get the biological parameters of interest, tracer kinetic modeling techniques are required. These techniques are conventionally applied after reconstruction of the PET data. In addition, to test for significance at the voxel level statistical parametric mapping is often used which requires all the images to be registered in a common spatial atlas, or stereotaxic space. Typically, this step is performed after PET image reconstruction as well.It is becoming increasingly clear that it is often better, in terms of achieving better quantification, to estimate the parameters of interest directly from the raw Poisson distributed PET data, rather than to first reconstruct and then separately post process the data.Therefore, the first aim of this project was to incorporate the registration to anatomical MR (or stereotaxic) space into the image reconstruction algorithm and assess its performance by comparing the results with those of conventional post-reconstruction registration. The second aim was to combine the simplified reference tissue model with the basis function method (SRTM-BFM) tracer kinetic model, with the recently developed direct 4D PET one-step late maximum likelihood expectation maximization (OSL-MLEM) reconstruction algorithm and compare its performance with that of the conventional post-reconstruction method. Finally, the methods developed and assessed for aims 1 and 2 were combined and applied on a [11C]raclopride-like simulated study comparing two conditions, to test whether or not statistical significance is increased in comparison to the conventional post-reconstruction method.This has the potential to improve current PET method(s) and constitutes an important step towards the goal of providing researchers not only with better results but directly interpretable results. Présentement, les données acquises avec la tomographie par émission de positron (TEP) doivent premièrement être reconstruites et par la suite, une analyse considérable est nécessaire afin de produire des images d'intérêt biologique pour les chercheurs. Le but principal de ce projet est de diminuer les étapes nécessaires, après reconstruction, en incluant chacune de ces étapes dans l'algorithme de reconstruction, permettant ainsi de respecter la nature des données brutes de la TEP, afin de procurer directement aux chercheurs des…