Method and apparatus for MR perfusion image acquisition using a notched RF saturation pulse
First Claim
1. A method of acquiring MR data comprising the steps of:
- selecting a volume of slice locations in which MR data is to be acquired;
transmitting a notched RF saturation pulse within the selected volume of slice locations, the notched RF saturation pulse having a stop-band between a pair of pass-bands; and
acquiring MR data for the slice location in the stop-band of the notched RF saturation pulse.
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Abstract
A method and apparatus is disclosed for MR perfusion acquisition using a notched RF saturation pulse. In acquiring such MR data, a volume of slice locations is selected in which MR data is to be acquired. Each given slice is prepared with a notched RF saturation pulse which has a stop-band between a pair of pass-bands. The stop-band is designed to not affect the spins in the next slice in which MR data is to be acquired thereby effectively increasing the TI and increasing SNR and contrast simultaneously. Since the notched saturation pulse saturates all the spins outside of the notched stop-band, the blood in the ventricular chamber is effectively saturated so that the resulting perfusion images have blood pool suppression. Additionally, the use of a 90° presaturation RF pulse provides a high level of immunity to the effects of arrhythmias or other variations in the patient'"'"'s heart rate. In order to keep the stop-band, or the notch, as wide as possible to overlap the boundaries of each slice location, it is preferable to interleave the acquisition of slice locations.
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Citations
26 Claims
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1. A method of acquiring MR data comprising the steps of:
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selecting a volume of slice locations in which MR data is to be acquired;
transmitting a notched RF saturation pulse within the selected volume of slice locations, the notched RF saturation pulse having a stop-band between a pair of pass-bands; and
acquiring MR data for the slice location in the stop-band of the notched RF saturation pulse. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of acquiring MR data with longer relaxation time (TI) comprising the steps of:
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(a) defining a plurality of slices in a volume of interest for which MR data acquisition is desired;
(b) transmitting a notched RF saturation pulse designed to saturate a next slice and all surrounding tissue in the volume of interest except a current slice;
(c) acquiring MR data from the current slice; and
(d) repeating steps (b) and (c) for each successive slice in the volume of interest wherein the next slice becomes the current slice and another slice becomes the next slice. - View Dependent Claims (12, 13, 14, 15)
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16. An MRI apparatus to acquire MR images with increased SNR and contrast in perfusion studies comprising:
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a magnetic resonance imaging (MRI) system having a plurality of gradient coils positioned about a bore of a magnet to impress a polarizing magnetic field and an RF transceiver system and an RF switch controlled by a pulse module to transmit RF signals to an RF coil assembly to acquire MR images; and
a computer programmed to;
select a volume of slice locations in which MR data is to be acquired;
transmit a notched RF saturation pulse within the selected volume of slice locations, the notched RF saturation pulse having a stop-band between a pair of pass-bands;
acquire MR data in the stop-band of the notched RF saturation pulse; and
reconstruct an MR image using the acquired MR data, such that the reconstructed MR image has increased SNR and increased image contrast over those acquired without a notched RF saturation pulse. - View Dependent Claims (17, 18, 19, 20, 21)
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22. A computer system for use with an MRI apparatus comprising a computer programmed from a computable readable storage medium having thereon a computer program programmed to:
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select a volume of slice locations in which MR data is to be acquired;
transmit a notched RF saturation pulse within the selected volume of slice locations, the notched RF saturation pulse having a stop-band between a pair of pass-bands; and
acquire NM data in the stop-band of the notched RF saturation pulse. - View Dependent Claims (23, 24, 25, 26)
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Specification