MR imaging using mutual interaction between different kinds of pools of nuclear spins
First Claim
1. A method of acquiring a magnetic resonance signal from an object having at least two kinds of pools of nuclei coupled with each other by at least one of the phenomena of chemical exchange and cross relaxation, comprising the steps of:
- exciting on a frequency-selective basis a specified pool of nuclei of said at least two kinds of pools of nuclei by means of an RF (radio-frequency) pulse whose frequency band substantially overlaps with a frequency band of said specified pool of nuclei, said specified pool of nuclei having a longer transverse relaxation time T2 than the remaining pool of nuclei; and
receiving the magnetic resonance signal induced by said specified pool of nuclei under said at least one of the phenomena.
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Accused Products
Abstract
In addition to the known MT (magnetization transfer) effect, an RMT (reverse MT) is newly found, which increases a detected MR signal strength. Both the MT and RMT effects can be explained with mutual interaction, such as phenomena of chemical exchange and/or cross relaxation, acted between a pool of water proton spins and another pool of macromolecule proton spins, for example, within an object. In order to enhance the MT or RMT effect, the frequency bandwidths of RF pulses, such as a 90° RF exciting pulse in a SE or FSE method, an inversion pulse in a FLAIR or fast FLAIR method, and others, are controlled. To enhance the MT effect, the bandwidth is controlled into a wider value (approx. more than 1250 Hz) than the normally (conventionally) used bandwidth, while to obtain the RMT effect, the bandwidth is controlled into a narrower value (approx. less than 1000 Hz) than the normally used bandwidth. Actively controlling the MT or RMT effect permits changed image contrast in MR imaging.
35 Citations
41 Claims
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1. A method of acquiring a magnetic resonance signal from an object having at least two kinds of pools of nuclei coupled with each other by at least one of the phenomena of chemical exchange and cross relaxation, comprising the steps of:
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exciting on a frequency-selective basis a specified pool of nuclei of said at least two kinds of pools of nuclei by means of an RF (radio-frequency) pulse whose frequency band substantially overlaps with a frequency band of said specified pool of nuclei, said specified pool of nuclei having a longer transverse relaxation time T2 than the remaining pool of nuclei; and receiving the magnetic resonance signal induced by said specified pool of nuclei under said at least one of the phenomena. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of magnetic resonance imaging of a subject having at least two kinds of pools nuclei coupled with each other by at least one of the phenomena of chemical exchange and cross relaxation, comprising the steps of:
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exciting a specified pool of nuclei of said at least two kinds of pools of nuclei by means of a first RF (radio-frequency) pulse whose frequency band substantially overlaps a frequency band of said specified pool of nuclei, said specified pool of nuclei having a longer transverse relaxation time T2 than the remaining pool of nuclei; receiving a first magnetic resonance signal induced by said specified pool of nuclei under said at least one of the phenomenal; exciting on a frequency-selective basis said at least two kinds of pools of nuclei by means of a second RF pulse whose frequency bandwidth is larger than the bandwidth of the specified pool of nuclei; receiving a second magnetic resonance signal induced by said specified pool of nuclei under said at least one of the phenomena; and producing a contrast image on the basis of said first and second magnetic resonance signals. - View Dependent Claims (14)
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15. A magnetic resonance imaging system for imaging a subject having at least two kinds of pools of nuclei coupled with each other by at least one of the phenomena of chemical exchange and cross relaxation, comprising:
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means for exciting a specified pool of nuclei by an RF pulse whose frequency band substantially overlaps a frequency band of said specified pool of nuclei, said specified pool of nuclei having a longer transverse relaxation time T2 than the remaining pool of nuclei; means for receiving a magnetic resonance signal induced by said specified, excited pool of nuclei under said at least one of the phenomena; and means for producing an MR image from the received magnetic resonance signal. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
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23. A method of acquiring a magnetic resonance signal from an object having at least two kinds of pools of nuclei coupled with each other by at least one of the phenomena of chemical exchange and cross relaxation, comprising the steps of:
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exciting on a frequency-selective basis a specified pool of nuclei of said at least two kinds of pools of nuclei by means of a reverse MT (magnetization transfer) RF (radio-frequency) pulse whose frequency bandwidth substantially overlaps with a frequency bandwidth of said specified pool of nuclei; and receiving the magnetic resonance signal induced by said specified pool of nuclei under said at least one of the phenomena. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. A method of magnetic resonance imaging of a subject having at least two kinds of pools nuclei coupled with each other by at least one of the phenomena of chemical exchange and cross relaxation, comprising the steps of:
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exciting a specified pool of nuclei of said at least two kinds of pools of nuclei by a first reverse MT (magnetization transfer) RF (radio-frequency) pulse whose frequency band substantially overlaps a frequency band of said specified pool of nuclei; receiving a first magnetic resonance signal induced by said specified pool of nuclei under said at least one of the phenomena; exciting on a frequency-selective basis said at least two kinds of pools of nuclei by a second reverse MT RF pulse whose frequency bandwidth is larger than the bandwidth of the specified pool of nuclei; receiving a second magnetic resonance signal induced by said specified pool of nuclei under said at least one of the phenomena; and producing a contrast image on the basis of said first and second magnetic resonance signals.
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35. A magnetic resonance imaging system for imaging a subject having at least two kinds of pools of nuclei coupled with each other by at least one of the phenomena of chemical exchange and cross relaxation, comprising:
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means for exciting a specified pool of nuclei by a reverse MT (magnetization transfer) RF (radio-frequency) pulse whose frequency band substantially overlaps a frequency band of said specified pool of nuclei; means for receiving a magnetic resonance signal induced by said specified, excited pool of nuclei under said at least one of the phenomena; and means for producing an MR image from the received magnetic resonance signal. - View Dependent Claims (36, 37, 38, 39, 40, 41)
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Specification