Echo‐volume imaging

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Abstract
Two single-shot volume imaging techniques are described. The first, single-echo echo-volume imaging, is essentially the echo-volume imaging (EVI) sequence suggested by Mansfield (J. Phys. C. 10, L55 (1977)). The second is a multi-spin-echo approach in which one plane of k-space is collected during each spin echo. In both techniques, phase encoding gradients are applied in the z direction, and three-dimensional k-space is filled by a raster pattern in Cartesian coordinates. Spatial saturation is used to avoid aliasing in the y direction, and a selective pulse is applied to excite the desired slab of tissue and eliminate aliasing in z. The average echo-times, measured from the center of the 90° pulse to the center of the acquisition k-space(kx= ky kz = 0), were 45 and 104 ms for single echo and multi-echo methods, respectively. Images of the human brain using both sequences are shown.