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Diffusion-weighted imaging (DWI) provides a noninvasive tool to probe tissue microstructure. We propose a simplified model of neural cytoarchitecture intended to capture the essential features important for water diffusion as measured by NMR. Two components contribute to the NMR signal in this model: (i) the dendrites and axons, which are modeled as long(More)
Relative cerebral blood flow (CBF) and tissue mean transit time (MTT) estimates from bolus-tracking MR perfusion-weighted imaging (PWI) have been shown to be sensitive to delay and dispersion when using singular value decomposition (SVD) with a single measured arterial input function. This study proposes a technique that is made time-shift insensitive by(More)
The principles of cerebral perfusion imaging by the method of dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) (bolus tracking) are described. The MRI signals underlying DSC-MRI are discussed. Tracer kinetics procedures are defined to calculate images of cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT).(More)
Due to its unique sensitivity to tissue microstructure, diffusion-weighted magnetic resonance imaging (MRI) has found many applications in clinical and fundamental science. With few exceptions, a more precise correspondence between physiological or biophysical properties and the obtained diffusion parameters remain uncertain due to lack of specificity. In(More)
Perfusion weighted MRI has proven very useful for deriving hemodynamic parameters such as CBF, CBV and MTT. These quantities are important diagnostically, e.g. in acute stroke, where they are used to delineate ischemic regions. Yet the standard method for estimating CBF based on singular value decomposition (SVD) has been demonstrated to underestimate(More)
PURPOSE To establish reference data and to study age-dependency for cerebral perfusion in various regions of the brain in a healthy population. MATERIAL AND METHODS Eighty healthy subjects of both genders from 22 to 85 years of age were studied with spin echo echo-planar dynamic susceptibility contrast MR imaging (DSC MRI) at 1.5 T. Cerebral blood volume(More)
Cerebral perfusion may be visualized by the dynamic imaging of an intravenously injected bolus (a few milliliters) of clinically approved gadolinium-containing contrast media. During its passage through the vasculature of the brain, the contrast agent induces magnetic field disturbances, which can be seen as signal loss on appropriately weighted dynamic(More)
Musicians exchange non-verbal cues as messages when they play together. This is particularly true in music with a sketchy outline. Jazz musicians receive and interpret the cues when performance parts from a regular pattern of rhythm, suggesting that they enjoy a highly developed sensitivity to subtle deviations of rhythm. We demonstrate that pre-attentive(More)
Absolute blood flow and blood volume measurements using perfusion weighted MRI require an accurately measured arterial input function (AIF). Because of limited spatial resolution of MR images, AIF voxels cannot be placed completely within a feeding artery. We present a two-compartment model of an AIF voxel including the relaxation properties of blood and(More)
The concentration of MRI tracers cannot be measured directly by MRI and is commonly evaluated indirectly using their relaxation effect. This study develops a comprehensive theoretical model to describe the transverse relaxation in perfused tissue caused by intravascular tracers. The model takes into account a number of individual compartments. The signal(More)