# US 5,349,295 A · Magnetic resonance imaging method and apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,349,295 A - Document ID: US5349295A - Status: Granted - Kind: A - Application number: 07/949,700 - Filed: 1992-09-23 - Granted: 1994-09-20 - Earliest claimed: 1991-09-25 - Assignees: Kabushiki Kaisha Toshiba - Inventors: Yu Tokunaga - Web page: https://patentgrep.com/patent/US5349295A ## CPC - G01R 33/561: by reduction of the scanning time, i.e. fast acquiring systems, e.g. using echo-planar pulse sequences - G01R 33/56509: {due to motion, displacement or flow, e.g. gradient moment nulling (G01R33/567 takes precedence)} - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract For the purpose of three-dimensionally imaging a selected three-dimensional region of a subject under examination on the basis of magnetic resonance phenomena exhibited by hydrogen atomic nuclei, a magnetic resonance imaging apparatus comprises a unit for carrying out the contrast enhanced-fuirier acquiered steadystate technique (CE-FAST) extended to three dimensions, an image reconstruction unit for reconstructing a plurality of relatively thin slice images on the basis of echo signals from the three-dimensional region acquired by the unit, a weighting unit for weighting differently the plurality of relatively thin slice images obtained by the image reconstructing unit, an adding unit for adding slice images obtained by the weighting unit so as to produce a surface anatomy scan image of the three-dimensional region, and an image display unit for displaying the surface anatomy image obtained by the adding unit. ## Claims ### Claim 1 A magnetic resonance imaging apparatus for generating three-dimensional image of a selected three-dimensional region of a subject on the basis of magnetic resonance phenomena exhibited by hydrogen atomic nuclei, comprising: means for applying a plurality of RF pulses spaced apart in time to said three-dimensional region of said subject at a pulse repetition time to generate a plurality of steady-state free precession magnetic resonance signals; means for applying a dephasing gradient magnetic field and a rephasing gradient magnetic field between consecutive RF pulses to cause a plurality of echo signals to be generated from the plurality of steady-state free precession magnetic resonance signals of said three-dimensional region; means for acquiring said echo signals; image reconstruction means for reconstructing a plurality of relatively thin slice images on the basis of said plurality of echo signals from the plurality of steady-state free precession magnetic resonance signals of said three-dimensional region acquired by said signal acquiring means; image producing means for producing a surface anatomy scan image on the basis of said plurality of images of relative thin slices obtained by said image reconstruction means; and image display means for displaying said surface anatomy image obtained by said image producing means. ### Claim 2 (depends on 1) The magnetic resonance imaging apparatus according to claim 1, in which said signal acquiring means includes three-dimensional imaging means for three-dimensionally imaging said three-dimensional region in accordance with the contrast enhanced-fuirier acquired steadystate technique (CE-FAST). ### Claim 3 (depends on 2) The magnetic resonance imaging apparatus according to claim 2, in which said three-dimensional imaging means includes means for carrying out a CE-FAST technique using a gradient magnetic field for reducing motion artifacts in the direction of signal readout which is one of said gradient magnetic fields. ### Claim 4 (depends on 2) The magnetic resonance imaging apparatus according to claim 2, in which said three-dimensional imaging means includes means for carrying out a CE-FAST technique using a gradient magnetic field for reducing motion artifacts in the direction of thickness of slices, which is one of said gradient magnetic fields. ### Claim 5 (depends on 1) The magnetic resonance imaging apparatus according to claim 1, in which said image producing means includes weighting means for weighting differently said plurality of relatively thin slice images obtained by said image reconstructing means; and adding means for adding slice images obtained by said weighting means to produce said surface anatomy scan image of said three-dimensional region. ### Claim 6 (depends on 1) The magnetic resonance imaging apparatus according to claim 1, in which said image producing means includes means for producing said surface anatomy scan image of said three-dimensional region by applying maximum projection to said plurality of relatively thin slice images obtained by said image reconstructing means. ### Claim 7 (depends on 1) The magnetic resonance imaging apparatus according to claim 1, in which said image displaying means includes means for displaying said surface anatomy scan image obtained by said image producing means on a stereoscopic basis. ### Claim 8 A magnetic resonance imaging method for generating three-dimensional image of a selected three-dimensional region of a subject on the basis of magnetic resonance phenomena exhibited by hydrogen atomic nuclei, comprising: the step for repeating the application of an RF pulse to said three-dimensional region of said subject at a short pulse repetition time to generate steady-state free precession magnetic resonance signals; the step for applying a dephasing gradient magnetic field and a rephasing gradient magnetic field to signal components in said magnetic resonance signals which get in phase [immediately prior to the application of the next between consecutive RF pulses, so as to cause echo signals to be generated from steady-state free precession magnetic resonance signals of said three-dimensional region; the step for acquiring said echo signal; and the step of reconstructing a plurality of relatively thin slice images on the basis of said echo signals from steady-state free precession magnetic resonance signals of said three-dimensional region acquired by said step of signal acquisition; the step of producing a surface anatomy scan image on the basis of said plurality of images of relatively thin slices obtained by said image reconstructing step; and the step of displaying said surface anatomy image obtained by said image producing step. ### Claim 9 (depends on 8) The magnetic resonance imaging apparatus according to claim 8, in which said signal acquiring step includes the step of three-dimensionally imaging said three-dimensional region in accordance with the contrast enhanced-fuirier acquired steadystate technique (CE-FAST). ### Claim 10 (depends on 9) The magnetic resonance imaging apparatus according to claim 9, in which said three-dimensionally imaging step includes the step of carrying out a CE-FAST technique using a gradient magnetic field for reducing motion artifacts in the direction of signal readout which is one of said gradient magnetic fields. ### Claim 11 (depends on 9) The magnetic resonance imaging apparatus according to claim 9, in which said three-dimensionally imaging step includes the step of carrying out a CE-FAST technique using a gradient magnetic field for reducing motion artifacts in the direction of thickness of slices, which is one of said gradient magnetic fields. ### Claim 12 (depends on 8) The magnetic resonance imaging method according to claim 8, in which said image producing step includes the step of weighting differently said plurality of relatively thin slice images obtained by said image reconstructing step; and the step of adding slice images obtained by said weighting step to produce said surface anatomy scan image of said three-dimensional region. ### Claim 13 (depends on 8) The magnetic resonance imaging method according to claim 8, in which said image producing step includes the step of producing said surface anatomy scan image of said three-dimensional region by applying maximum projection to said plurality of relatively thin slice images obtained by said image reconstructing step. ### Claim 14 (depends on 8) The magnetic resonance imaging method according to claim 8, in which said image displaying step includes the step of displaying said surface anatomy scan image obtained by said image producing step on a stereoscopic basis. ### Claim 15 A magnetic resonance imaging apparatus to be adapted to achieve three-dimensional imaging of a selected three-dimensional region of a subject on the basis of magnetic resonance phenomena exhibited by hydrogen atomic nuclei, comprising: means for performing a sequence defined by the contrast enhanced-Fourier acquired steady-state technique (CE-FAST) extended to three dimensions; image reconstruction means for reconstructing a plurality of relatively thin slice images on the basis of said echo signals from said three-dimensional region acquired by said means; weighting means for weighting differently said plurality of relative thin slice images obtained by said image reconstructing means; adding means for adding slice images obtained by said weighting means to produce a surface anatomy scan image of said three-dimensional region; image producing means for producing said surface anatomy scan image on the basis of said plurality of relatively thin slice images obtained by said image reconstruction means; and image display means for displaying said surface anatomy image obtained by said image producing means.