title: Non-Gaussian diffusion imaging for enhanced contrast of brain tissue affected by ischemic stroke.
abstract: Recent diffusion MRI studies of stroke in humans and animals have shown that the quantitative parameters characterising the degree of non-Gaussianity of the diffusion process are much more sensitive to ischemic changes than the apparent diffusion coefficient (ADC) considered so far as the "gold standard". The observed changes exceeded that of the ADC by a remarkable factor of 2 to 3. These studies were based on the novel non-Gaussian methods, such as diffusion kurtosis imaging (DKI) and log-normal distribution function imaging (LNDFI). As shown in our previous work investigating the animal stroke model, a combined analysis using two methods, DKI and LNDFI provides valuable complimentary information. In the present work, we report the application of three non-Gaussian diffusion models to quantify the deviations from the Gaussian behaviour in stroke induced by transient middle cerebral artery occlusion in rat brains: the gamma-distribution function (GDF), the stretched exponential model (SEM), and the biexponential model. The main goal was to compare the sensitivity of various non-Gaussian metrics to ischemic changes and to investigate if a combined application of several models will provide added value in the assessment of stroke. We have shown that two models, GDF and SEM, exhibit a better performance than the conventional method and allow for a significantly enhanced visualization of lesions. Furthermore, we showed that valuable information regarding spatial properties of stroke lesions can be obtained. In particular, we observed a stratified cortex structure in the lesions that were well visible in the maps of the GDF and SEM metrics, but poorly distinguishable in the ADC-maps. Our results provided evidence that cortical layers tend to be differently affected by ischemic processes.
authors.affiliation: Institute of Neuroscience and Medicine - 4, Forschungszentrum Juelich GmbH, Juelich, Germany ; Department of Neurology, Faculty of Medicine, JARA, RWTH Aachen University, Aachen, Germany.
authors.forename: Farida
authors.initials: F
authors.lastname: Grinberg
authors.affiliation: Institute of Neuroscience and Medicine - 4, Forschungszentrum Juelich GmbH, Juelich, Germany.
authors.forename: Ezequiel
authors.initials: E
authors.lastname: Farrher
authors.affiliation: NeuroSpin, Commissariat à l'énergie atomique et aux énergies alternatives (CEA Saclay), Gif-sur-Yvette, France.
authors.forename: Luisa
authors.initials: L
authors.lastname: Ciobanu
authors.affiliation: NeuroSpin, Commissariat à l'énergie atomique et aux énergies alternatives (CEA Saclay), Gif-sur-Yvette, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Geffroy
authors.affiliation: NeuroSpin, Commissariat à l'énergie atomique et aux énergies alternatives (CEA Saclay), Gif-sur-Yvette, France.
authors.forename: Denis
authors.initials: D
authors.lastname: Le Bihan
authors.affiliation: Institute of Neuroscience and Medicine - 4, Forschungszentrum Juelich GmbH, Juelich, Germany ; Department of Neurology, Faculty of Medicine, JARA, RWTH Aachen University, Aachen, Germany.
authors.forename: N Jon
authors.initials: NJ
authors.lastname: Shah
mesh_terms: D000465:Algorithms; D000818:Animals; D001921:Brain / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging; D004195:Disease Models, Animal; D007091:Image Processing, Computer-Assisted; D008297:Male; D015233:Models, Statistical; D051381:Rats; D020521:Stroke / Q000175:diagnosis*