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5349292 Magnetic resonance imaging apparatus
XVIII
New Patents
5348011 SHARED EXCITATION PHASE ENCODE GROUPING FOR IMPROVED THROUGHPUT CARDIACGA;iD&++‘lRI CINE NessAiver Moriel S UNITED STATES International Inc
Cleveland Heights, OH, Assigned to Picker
A patient’s cardiac cycle is monitored (34) for a characteristic point (54) of the cardiac cycle. Following or in response to the characteristic point, a series of field echo sequences (FIG. 3 1 are applied to generate magnetic resonance echoes (50a, 50b, 5Oc, etc.) at about 10 millisecond intervals (TR=lO ms) following the characteristic point. The echoes are phase encoded (44) such that echoes phase encoded in a lowest frequency or central most segment (I) of k-space are generated at regular intervals. Between temporal consecutive segment (I) echoes, echoes with higher frequency phase encoding from segments (II) and (III) (FIG. 4 1, segments (II-IV) (FIGS. 5A, 5B), etc. are generated. The views are sorted (60) into data sets (62a, 62b, 62c, etc.) such that the central most views are sent to only a single data set and at least some of the higher frequency views are conveyed to two data sets, i.e., the high frequency views are shared or commonly used by two data sets. Each data set is reconstructed (64) into a corresponding frame image representation (66). In this manner, the central most views which carry tbe most information are unique to each image, but higher frequency views are shared by two temporally adjacent images. The images are displayed sequentially or in another selected order on a video monitor (76).
5348012 MAGNETIC RESONANCE IMAGING APPARATUS AND METHOD FOR FORMING AN IMAGE OF AN ARTERY Kojima Fumitosbi Ootawara, JAPAN Assigned to Kabusbiki Kaisba Toshiba A gradient field is applied in a coronal scheme
such that a slice region along the flowing direction of a blood vessel, i.e., along the body axis is set as an imaging area. Of regions adjacent to the imaging region in the body axis direction, a region including a blood vessel as a target of imaging (in this case, an artery) through which the blood flows toward the imaging region is not excited, but only the imaging region is selectively excited. Then, since a spin in the artery is supplied to the imaging region in a fresh state, the image of this spin is formed with a signal level higher than that of a stationary spin remaining in the imaging region. Since the presatnrated blood in the artery in the imaging region is returned at its peripheral portion to flow tbrougb the vein, tbe spin in the vein is already saturated, its signal level is lower than that of the spin in the artery, and the image of this spin is not formed. As a result, the image of the state of the artery can be formed witbin a short period of time.
5349292 MAGNETIC IMAGING
RESONANCE APPARATUS
Sugiura Satosb Ootawara, JAPAN Assigned to Kubusbiki Kaisba Toshiba A magnetic resonance imaging apparatus based on a multi-echo imaging scheme and a multi-slice imaging scheme, is arranged to acquire all components of an echo signal which corresponds to low-frequency components in an image which is smalI in the absolute value of tbe phase encoding amount in a sufficient time to ensure a desired signal-to-noise ratio and to acquire echo signals which correspond to high-frequency components in the image which are large in the absolute value of the phase encoding amount in acquisition times shorter than that time to ensure a desired signal-to-noise ratio. The signal acquisition time can he reduced by shortening the time interval at which the 180 degrees pulses are generated. Due to reducing tbe signal acquisition time, parts of the echo signal in the read direction are not acquired. The components which have not been acquired are estimated by use of complex conjugate data of acquired data or mere 0 values for image reconstruction. Thereby, image data acquisition time for one slice can he reduced to reserve the number of multi-slice aquisitions without degrading the signal-to-noise ratio in the image.
New Patents
5348011 SHARED EXCITATION PHASE ENCODE GROUPING FOR IMPROVED THROUGHPUT CARDIACGA;iD&++‘lRI CINE NessAiver Moriel S UNITED STATES International Inc
Cleveland Heights, OH, Assigned to Picker
A patient’s cardiac cycle is monitored (34) for a characteristic point (54) of the cardiac cycle. Following or in response to the characteristic point, a series of field echo sequences (FIG. 3 1 are applied to generate magnetic resonance echoes (50a, 50b, 5Oc, etc.) at about 10 millisecond intervals (TR=lO ms) following the characteristic point. The echoes are phase encoded (44) such that echoes phase encoded in a lowest frequency or central most segment (I) of k-space are generated at regular intervals. Between temporal consecutive segment (I) echoes, echoes with higher frequency phase encoding from segments (II) and (III) (FIG. 4 1, segments (II-IV) (FIGS. 5A, 5B), etc. are generated. The views are sorted (60) into data sets (62a, 62b, 62c, etc.) such that the central most views are sent to only a single data set and at least some of the higher frequency views are conveyed to two data sets, i.e., the high frequency views are shared or commonly used by two data sets. Each data set is reconstructed (64) into a corresponding frame image representation (66). In this manner, the central most views which carry tbe most information are unique to each image, but higher frequency views are shared by two temporally adjacent images. The images are displayed sequentially or in another selected order on a video monitor (76).
5348012 MAGNETIC RESONANCE IMAGING APPARATUS AND METHOD FOR FORMING AN IMAGE OF AN ARTERY Kojima Fumitosbi Ootawara, JAPAN Assigned to Kabusbiki Kaisba Toshiba A gradient field is applied in a coronal scheme
such that a slice region along the flowing direction of a blood vessel, i.e., along the body axis is set as an imaging area. Of regions adjacent to the imaging region in the body axis direction, a region including a blood vessel as a target of imaging (in this case, an artery) through which the blood flows toward the imaging region is not excited, but only the imaging region is selectively excited. Then, since a spin in the artery is supplied to the imaging region in a fresh state, the image of this spin is formed with a signal level higher than that of a stationary spin remaining in the imaging region. Since the presatnrated blood in the artery in the imaging region is returned at its peripheral portion to flow tbrougb the vein, tbe spin in the vein is already saturated, its signal level is lower than that of the spin in the artery, and the image of this spin is not formed. As a result, the image of the state of the artery can be formed witbin a short period of time.
5349292 MAGNETIC IMAGING
RESONANCE APPARATUS
Sugiura Satosb Ootawara, JAPAN Assigned to Kubusbiki Kaisba Toshiba A magnetic resonance imaging apparatus based on a multi-echo imaging scheme and a multi-slice imaging scheme, is arranged to acquire all components of an echo signal which corresponds to low-frequency components in an image which is smalI in the absolute value of tbe phase encoding amount in a sufficient time to ensure a desired signal-to-noise ratio and to acquire echo signals which correspond to high-frequency components in the image which are large in the absolute value of the phase encoding amount in acquisition times shorter than that time to ensure a desired signal-to-noise ratio. The signal acquisition time can he reduced by shortening the time interval at which the 180 degrees pulses are generated. Due to reducing tbe signal acquisition time, parts of the echo signal in the read direction are not acquired. The components which have not been acquired are estimated by use of complex conjugate data of acquired data or mere 0 values for image reconstruction. Thereby, image data acquisition time for one slice can he reduced to reserve the number of multi-slice aquisitions without degrading the signal-to-noise ratio in the image.