Coronary magnetic resonance angiography using motion matched acquisition
First Claim
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1. A method for imaging arteries using an MRA pulse sequence in which a series of views are acquired to sample k-space, the steps comprising:
- a) performing a scout scan using an NMR pulse sequence to measure movement of the arteries during a cardiac cycle;
b) identifying a quiescent period during the cardiac cycle in which the measured artery movement is minimal; and
c) acquiring the views from which an image is reconstructed using the MRA pulse sequence over a succession of cardiac cycles, and arranging the view order in this acquisition such that the views which sample a central region of k-space are acquired during the quiescent periods of the cardiac cycles and views which sample peripheral regions of k-space are acquired during portions of the cardiac cycles outside the quiescent periods of the cardiac cycles.
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Abstract
Coronary arteries are imaged using a cardiac gated, 3DFT fast gradient recalled echo MRA pulse sequence. A scout scan is performed to measure motion during a cardiac or respiratory cycle and a quiescent period of minimal artery motion is identified. Image data is acquired during a succession of cardiac cycles, and the view order is selected to sample the center of k-space during the quiescent period of each cardiac and or respiratory cycle to reduce motion artifacts.
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Citations
11 Claims
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1. A method for imaging arteries using an MRA pulse sequence in which a series of views are acquired to sample k-space, the steps comprising:
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a) performing a scout scan using an NMR pulse sequence to measure movement of the arteries during a cardiac cycle;
b) identifying a quiescent period during the cardiac cycle in which the measured artery movement is minimal; and
c) acquiring the views from which an image is reconstructed using the MRA pulse sequence over a succession of cardiac cycles, and arranging the view order in this acquisition such that the views which sample a central region of k-space are acquired during the quiescent periods of the cardiac cycles and views which sample peripheral regions of k-space are acquired during portions of the cardiac cycles outside the quiescent periods of the cardiac cycles. - View Dependent Claims (2, 3, 4, 5, 6)
i) performing the NMR pulse sequence repeatedly during the cardiac cycle to acquire a plurality of NMR echo signals;
ii) transforming the NMR echo signals to produce a scout image;
iii) detecting a cardiac cavity wall in the scout image; and
iv) measuring the movement of the cardiac cavity wall.
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3. The method as recited in claim 1 in which the view order is arranged such that views which sample a peripheral region of k-space are acquired for a time period prior to the quiescent period in each of the succession of cardiac cycles.
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4. The method as recited in claim 3 in which the view order is arranged such that views which sample the peripheral region of k-space are also acquired for a time period after the quiescent period in each of the succession of cardiac cycles.
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5. The method as recited in claim 3 in which the peripheral views acquired prior to each quiescent period are acquired in descending view order.
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6. The method as recited in claim 4 in which the peripheral views acquired after each quiescent period are acquired in ascending view order.
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7. A method for imaging patient arteries with an MRI system using an MRA pulse sequence in which a series of views are acquired to sample k-space, the steps comprising:
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a) performing a scout scan using an NMR pulse sequence to measure movement of the arteries during an acquisition window;
b) dividing the acquisition window into a plurality of time segments including a quiescent time segment during which there is minimal arterial motion;
c) producing a view order table by mapping each time segment to a corresponding region of k-space to be sampled and wherein the quiescent time segment is mapped to a central region of k-space and another time segment is mapped to a peripheral region of k-space;
d) acquiring image data using the MRA pulse sequence during a series of acquisition windows, wherein each region of k-space is sampled during its corresponding time segment in each acquisition window. - View Dependent Claims (8, 9, 10, 11)
performing a second scout scan to measure movement of the arteries during a cardiac acquisition window;
dividing the cardiac acquisition window into a plurality of cardiac time segments including a cardiac quiescent time segment during which there is minimal arterial motion; and
wherein the view order table produced in step c) includes mapping the cardiac time segments to corresponding regions of k-space.
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Specification