Basic principles of magnetic resonance imaging. An Azure service principal is a security identity used by user-created apps, services, and automation tools to access specific Azure resources. All you really need to know about MRI physics. Questions and answers in magnetic resonance imaging.
The higher the spatial frequency, the smaller are the details of the image (edges and spatial resolution). Periphery of k-space does not correspond to periphery of the image : it contains high-spatial-frequency information.Most image information is contained in low-spatial-frequency information, corresponding to general shape and contrast.Center of k-space contains low-spatial-frequency information.In other words, a point in k-space encodes for image signal variations in the same direction as the line passing through this point and the center of k-space. The data along a line passing through the center of k-space represent the Fourier transform of the projection of the image onto a line with the same orientation.Each point of the MR image is the result of the combination of all the data of k-space.Each point of k-space encodes for spatial information of the entire MR image.Gradients are bipolar (negative or positive), so it is possible to move in opposite directions from the center (to the left or the right, and to the top or the bottom). The higher is the net strength of the gradient, or the longer the gradient is applied, the farther from the origin of k-space the data will be located. If no gradient is applied (or if the net effect of the gradient is null), the location is at the center of k-space. The location of the data in k-space depends on the strength and the duration of the gradients.These data are mapped into k-space so that an inverse 2D Fourier transform reconstructs the MR image. These gradients allow the encoding of spatial data as spatial frequency information. Spatial encoding in MR imaging uses magnetic field gradients.To link contrast, spatial resolution and field of view to k-space.To describe the k-space trajectory with a spin echo sequence.To state the relations between RF pulses, gradients and navigation in k-space.
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