MRI apparatus and method using sample filtering based on time shifts caused by temporal variations in magnetic field strength
First Claim
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1. An MRI apparatus comprising:
- an application unit that applies a readout gradient magnetic field in which magnetic field strength thereof varies with time and RF pulses to a subject placed in a static magnetic field in accordance with a predetermined pulse sequence;
a receiving unit that receives an MR signal obtained from the subject to which the readout gradient magnetic field and the RF pulses are applied;
an AD converter that converts the received MR signal from analog to digital, and samples discrete MR-signal values;
a filtering processing unit that performs filtering processing on the sampled discrete MR-signal values, includinga filter-coefficient setting unit that sets a plurality of filter coefficients to be used for the filtering processing with respect to each point of sampling time at which the filtering processing is to be performed, based on time-shift amounts corresponding to variations in an MR-signal frequency arising from temporal variations in the magnetic field strength, anda product-sum operating unit that performs the filtering processing on the MR-signal values by performing a product-sum operation between the filter coefficients and the MR-signal values; and
an image-data creating unit that creates image data based on the MR-signal values on which the filtering processing is performed.
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Abstract
An MRI apparatus includes a filtering control unit that filters discrete MR-signal values. A filter-coefficient setting unit sets a plurality of filter coefficients with respect to each point of sampling time, based on time-shift amounts corresponding to variations in an MR-signal frequency arising from temporal variations in the magnetic field strength. A product-sum operating unit filters the MR-signal values by performing a product-sum operation between the filter coefficients and the MR-signal values. An image-data creating unit creates image data based on the MR-signal values on which the filtering processing is performed.
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Citations
9 Claims
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1. An MRI apparatus comprising:
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an application unit that applies a readout gradient magnetic field in which magnetic field strength thereof varies with time and RF pulses to a subject placed in a static magnetic field in accordance with a predetermined pulse sequence; a receiving unit that receives an MR signal obtained from the subject to which the readout gradient magnetic field and the RF pulses are applied; an AD converter that converts the received MR signal from analog to digital, and samples discrete MR-signal values; a filtering processing unit that performs filtering processing on the sampled discrete MR-signal values, including a filter-coefficient setting unit that sets a plurality of filter coefficients to be used for the filtering processing with respect to each point of sampling time at which the filtering processing is to be performed, based on time-shift amounts corresponding to variations in an MR-signal frequency arising from temporal variations in the magnetic field strength, and a product-sum operating unit that performs the filtering processing on the MR-signal values by performing a product-sum operation between the filter coefficients and the MR-signal values; and an image-data creating unit that creates image data based on the MR-signal values on which the filtering processing is performed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An MRI method comprising:
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applying a readout gradient magnetic field in which magnetic field strength thereof varies with time and RF pulses to a subject placed in a static magnetic field in accordance with a predetermined pulse sequence; receiving an MR signal obtained from the subject to which the readout gradient magnetic field and the RF pulse are applied; converting the received MR signal from analog to digital, and sampling discrete MR-signal values; performing filtering processing on the sampled discrete MR-signal values, by setting a plurality of filter coefficients to be used for the filtering processing with respect to each point of sampling time at which the filtering processing is to be performed, based on time-shift amounts corresponding to variations in an MR-signal frequency arising from temporal variations in the magnetic field strength, and performing the filtering processing on the MR-signal values by performing a product-sum operation between the filter coefficients and the MR-signal values; and creating image data based on the MR-signal values on which the filtering processing is performed.
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Specification