# US 2013/0278263 A1 · Parallel mri method using calibration scan, coil sensitivity maps and navigators for rigid motion compensation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0278263 A1 - Document ID: US20130278263A1 - Status: Published application - Kind: A1 - Application number: 13/995,378 - Filed: 2011-12-16 - Published: 2013-10-24 - Earliest claimed: 2010-12-22 - Assignees: Koninklijke Philips Electronics N.V. - Inventors: Feng Huang; Wei Lin - Web page: https://patentgrep.com/patent/US20130278263A1 ## CPC - G01R 33/56509: {due to motion, displacement or flow, e.g. gradient moment nulling (G01R33/567 takes precedence)} - G01R 33/5611: {Parallel magnetic resonance imaging, e.g. sensitivity encoding [SENSE], simultaneous acquisition of spatial harmonics [SMASH], unaliasing by Fourier encoding of the overlaps using the temporal dimension [UNFOLD], k-t-broad-use linear acquisition speed-up technique [k-t-BLAST], k-t-SENSE (structural details of arrays of sub-coils G01R33/3415)} - G01R 33/5676: {Gating or triggering based on an MR signal, e.g. involving one or more navigator echoes for motion monitoring and correction} - G01R 33/58: Calibration of imaging systems, e.g. using test probes {, Phantoms; Calibration objects or fiducial markers such as active or passive RF coils surrounding an MR active material} - G01R 33/56325: {Cine imaging} - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract Magnetic resonance (MR) calibration data are acquired using a plurality of radio frequency receive coils, and both coil sensitivity maps and reference projection vectors are generated based on the MR calibration data. During imaging, extra navigator projection vectors are acquired, or part of the imaging data can be used as navigator projection vectors. Partially parallel imaging (PPI) can performed to enhance the navigation information. The navigator projection vectors and the reference projection vectors are sensitivity weighted using the coil sensitivity maps to generate navigator sensitivity weighted projection vectors (navigator SWPV) and reference sensitivity weighted projection vectors (reference SWPV) respectively, and these are compared to generate subject position information. The subject motions are compensated prospectively or retrospectively using the generated subject position information. The motion compensation may be prospective, performed by adjusting an imaging volume of the PPI based on the subject position information. ## Claims ### Claim 1 A method comprising: acquiring magnetic resonance calibration data using a plurality of radio frequency receive coils; generating coil sensitivity maps for the radio frequency receive coils based on the MR calibration data; generating reference projection vectors based on the MR calibration data; performing magnetic resonance imaging including acquiring magnetic resonance imaging data; generating magnetic resonance navigator projection vectors based on a portion of the acquired magnetic resonance imaging data or extra data acquired with the magnetic resonance imaging data; comparing the magnetic resonance navigator projection vectors with the reference projection vectors to generate subject position information; and in the magnetic resonance imaging, compensating for subject motion prospectively or retrospectively using the generated subject position information. ### Claim 2 (depends on 1) The method as set forth in claim 1, further comprising: sensitivity weighting the magnetic resonance navigator projection vectors and the reference projection vectors using the coil sensitivity maps to generate magnetic resonance navigator sensitivity weighted projection vectors (navigator SWPV) and reference sensitivity weighted projection vectors (reference SWPV) respectively; wherein the comparing comprises comparing the magnetic resonance navigator SWPV with the reference SWPV to generate the subject position information. ### Claim 3 (depends on 2) The method as set forth in claim 2, wherein the comparing comprises: computing cross correlations between the magnetic resonance navigator SWPV and the reference SWPV; and generating the subject position information based on the computed cross correlations. ### Claim 4 (depends on 1) The method as set forth in claim 1, wherein the comparing comprises: computing cross correlations between the magnetic resonance navigator projection vectors and the reference projection vectors; and generating the subject position information based on the computed cross correlations. ### Claim 5 (depends on 1) The method as set forth in claim 1, wherein the magnetic resonance imaging comprises partially parallel imaging (PPI) selected from a group consisting of sensitivity encoding (SENSE), simultaneous acquisition off spatial harmonics (SMASH), generalized autocalibrating partially parallel acquisition (GRAPPA). ### Claim 6 (depends on 1) The method as set forth in claim 1, further comprising: displaying the one or more reconstructed magnetic resonance images on a display device. ### Claim 7 (depends on 1) The method as set forth in claim 1, wherein the one or more reconstructed magnetic resonance images comprise a time sequence of reconstructed magnetic resonance images and the method further comprises: displaying a CINE sequence of the time sequence of reconstructed magnetic resonance images on a display device. ### Claim 8 (depends on 1) The method as set forth in claim 1, wherein the compensating comprises: performing prospective motion compensation by adjusting an imaging volume based on the generated subject position information. ### Claim 9 (depends on 1) The method as set forth in claim 1, wherein the compensating comprises: performing retrospective motion compensation based on the subject position information. ### Claim 10 (depends on 1) The method as set forth in claim 1, wherein at least the generating of coil sensitivity maps, the generating of reference projection vectors, and the comparing of the magnetic resonance navigator projection vectors with the reference projection vectors are performed by a digital processor. ### Claim 11 A method comprising: acquiring magnetic resonance (MR) calibration data using a plurality of radio frequency receive coils; generating coil sensitivity maps for the radio frequency receive coils based on the MR calibration data; acquiring magnetic resonance navigator projection vectors and sensitivity weighting the acquired magnetic resonance navigator projection vectors using the coil sensitivity maps to generate navigator sensitivity weighted projection vectors (navigator SWPV); performing magnetic resonance imaging; generating subject position informational) based on the navigator SWPV; and in the magnetic resonance imaging, compensating for subject motion prospectively or retrospectively using the generated subject position information. ### Claim 12 (depends on 11) The method as set forth in claim 11, wherein the generating of subject position information comprises: computing cross correlations between the navigator SWPV and reference projection vectors; and generating the subject position information based on the computed cross correlations. ### Claim 13 (depends on 12) The method as set forth in claim 12, further comprising: sensitivity weighting the reference projection vectors using the coil sensitivity maps to generate reference sensitivity weighted projection vectors (reference SWPV); wherein the computing cross correlations comprises computing cross correlations between the navigator SWPV and the reference SWPV. ### Claim 14 (depends on 12) The method as set forth in claim 12, further comprising: generating the reference projection vectors based on magnetic resonance data acquired prior to acquiring imaging data. ### Claim 15 (depends on 12) The method as set forth in claim 12, further comprising: generating the reference projection vectors based on the MR calibration data. ### Claim 16 (depends on 11) The method as set forth in claim 11, wherein the magnetic resonance imaging comprises partially parallel imaging (PPI) selected from a group consisting of sensitivity encoding (SENSE), simultaneous acquisition off spatial harmonics (SMASH), generalized autocalibrating partially parallel acquisition (GRAPPA). ### Claim 17 (depends on 11) The method as set forth in claim 11, further comprising: displaying a motion-compensated reconstructed magnetic resonance image generated by the magnetic resonance imaging and compensating on a display device. ### Claim 18 (depends on 11) The method as set forth in claim 11, wherein the compensating comprises: performing prospective motion compensation by adjusting an imaging volume based on the generated subject position information. ### Claim 19 (depends on 11) The method as set forth in claim 11, wherein at least the generating of coil sensitivity maps, the sensitivity weighting of the acquired magnetic resonance navigator projection vectors, and the generating of subject position information are performed by a digital processor. ### Claim 20 (depends on 1) An apparatus comprising: a magnetic resonance (MR) scanner; a plurality of radio frequency receive coils; and a data processing device configured to cooperate with the MR scanner and the radio frequency receive coils to perform a method as set forth in claim 1.