Method for the determination of the nuclear magnetization distribution in a layer of a region under investigation, and nuclear spintomograph for carrying out the method
AssigneeU.S. Philips Corporation
InventorGraeme-Colin McKinnon
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Abstract
The invention relates to a sequence with a very short echo time. However, during the measurement, there is a constant gradient, the direction of which is varied from sequence to sequence, while its magnitude remains constant. The shortening of the echo time is achieved in that in the first instance on both sides of the layer to be excited, two comparatively thick regions are excited. The nuclear magnetization excited in these regions is dephased, and subsequently a likewise comparatively thick region is excited by a further high-frequency pulse, which encompasses the layer to be excited as well as a part of the regions on both sides of the layer.
Claims10
A method for determining nuclear magnetization distribution in a layer of a region under investigation, which region is exposed, in the presence of a homogeneous steady magnetic field, to a number of sequences, each sequence comprising at least two high-frequency pulses, a magnetic gradient field effective during at least one high-frequency pulse and having a gradient extending perpendicularly to the layer, each sequence further including a measurement interval which occurs after the pulses and during which a further magnetic gradient field with a gradient which extends in the layer and which is variable in its direction is applied and, for the reconstruction of the absorption distribution, the nuclear spin resonance signals generated in the region under investigation are recorded, characterized in that in each sequence the nuclear spin resonance in two regions each disposed on a respective one of two sides of the layer is excited by at least one high-frequency pulse, and in that, after dephasing of the excited nuclear magnetization, the nuclear magnetization is excited by a further high-frequency pulse in a region encompassing a part of said two regions as well as the layer.
Dependencies are inferred from the claim text.