GRAPPA - kanamri.umin.ne.jp

1 30thKanagawa MRI Technical MeetingYokohama City University Medical (fri) GRAPPA MRI Part4 130thKanagawa MRI Technical MeetingYokohama City University Medical (fri)Agenda2 Parallel Imaigng GRAPPA GRAPPA 30thKanagawa MRI Technical MeetingYokohama City University Medical (fri) 726 679 47 1,926 / MAGNETOM VB19(SIEMENS) 0 MR 4 (IBD) 30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)What is the Parallel Imaging?430thKanagawa MRI Technical MeetingYokohama City University Medical (fri)Parallel 5 parallel skiparallel barparallel circuit30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)Parallel Imaging k-space Coil 1 Coil 2 SMASH FFTk-space based algorithm 30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)7PI 1998 Bird CageCoilTA5:502012 16chMulti CoilTA2.

2 40 With SENSE30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)8PI MultichannelPISinglechannel30thKanagawa MRI Technical MeetingYokohama City University Medical (fri) 2D-imaging)9 Spin Echo TR N phase Average Turbo Spin Echo TR N phase Average Turbo Factor Gradient Echo TR N phase Average : TR : N phase For shortening the TAk-space TR Nphase( )readoutphasek-space30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)10 What happens when If shorten the TR?30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)TR 11 TR For shortening the TA T1 SNR T2WI-TSE (TE=100msec)90 180 90 180 echoechoTR T2 TR 2000TR 4000TR 600030thKanagawa MRI Technical MeetingYokohama City University Medical (fri)TR For shortening the TA SAR / TR (B0 R )2 SAR : : RF B0: : R: : 90 180 90 180 echoechoTR TR 30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)13 What happens when If reduce the Nphase?

3 30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)N phase 14 Rectangular FOV ( FOV phase ) Rectangular Matrix ( Phase Resolution ) Half Fourier ( Phase Partial Fourier ) For shortening the TA readoutphasek-spacereadoutphasek-space Matrix : 256*256 Pixel size : 1mm2 SNR : 100%TA : 100sec30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)15N phase For shortening the TA readoutphasek-space Rectangular FOV ( FOV phase ) TA SNR Rectangular FOV 50% TA : 50sec Matrix size : 256 256 Pixel size : 1 1mm2 SNR : 71% 50%100%30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)16N phase k-space TA SNR For shortening the TA readoutphasek-space Rectangular Matrix ( Phase Resolution ) Rectangular Matrix 50%(128) TA : 50sec Matrix size : 128 256 Pixel size : 2 1mm2 SNR : 141% 50%100%30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)17N phase SNR TA SNR ringing For shortening the TA readoutphasek-space Half Fourier (Phase Partial Fourier) Half Fourier 50% TA : 50sec Matrix size : 256 256 Pixel size : 1 1mm2 SNR.

4 71% 50%100%30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)TR Nphase 1830thKanagawa MRI Technical MeetingYokohama City University Medical (fri)SENSE GRAPPA19 ImagebasedCoil 1 Coil 2k-spacebasedSENSEGRAPPAK-space FFTFFTFFTFFT30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)The principle of GRAPPA2030thKanagawa MRI Technical MeetingYokohama City University Medical (fri) SMASH Auto SMASH VDAuto SMASH GRAPPA ARC CAIPIRINHA PI 21 SENSE PLIS mSENSE ASEET SPEEDER RAPIDI mage-basedalgorithmsk-space-basedalgorit hms30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)The history of evolution22k-space-based algorithms30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)23 SMASH, SENSE, PILS, GRAPPA How to Choose the Optimal Method Martin Blaimer, Felix Breuer, Matthias Mueller, Robin M.

5 Heidemann, Mark A. Griswold, and Peter M. JakobTop MagnResonImaging Volume 15, Number 4, August 2004 30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)SMASH step fitting raw data ( spatial harmonics ) fitting Coil 1 k-spaceCoil 2 k-space 30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)AUTO-SMASH25 auto calibration signal( ACS ) k-space fitting K-space SNR k-space SNR Coil 1 k-spaceCoil 2 k-space ACS 30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)VariableDensity-AUTO-SMASHACS k-space fitting SNR SNR Coil 1 k-spaceCoil 2 k-space ACS 30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)

6 GRAPPA27 ACS Sliding block approach ACS line fitting SNR magnitude Coil 1 k-spaceCoil 2 k-space FFTFFT ACS 30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)28 SMASH, SENSE, PILS, GRAPPA How to Choose the Optimal Method Martin Blaimer, Felix Breuer, Matthias Mueller, Robin M. Heidemann, Mark A. Griswold, and Peter M. JakobTop MagnResonImaging Volume 15, Number 4, August 2004 30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)GRAPPA29 Coil 1 Coil 2K-space slideingblockapproach CombinedCoil 1 Coil 2 Coil 1 Coil 2 ACS30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)30 30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)Characteristic of GRAPPA3130thKanagawa MRI Technical MeetingYokohama City University Medical (fri) GRAPPA 32 k-space Redaction -Factor Reference line ( ACS ) geometry -factor k phase over sampling30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)

7 PI SNR33 MR Parallel imaging SNR 2006 map SNR PIMAPg-factor MAPSNR convMAP R-factor voxel 30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)34 What happens if you change theReductionFactor?30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)k-space 35 SNR PI SNR conventionalg-factor R-factor Reduction Factor ASSET factor Acceleration factor Pat factor SENSE factorreadoutphaseRf= 2readoutphaseRf= 3 1 k-space encode 30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)k-space 36 SNR PI SNR conventionalg-factor R-factorGeometry Factor / 30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)Reduction Factor 37 SNRSNRTA(sec)TA0510012345 Reduction Factorg-factorg-factorMAXg-factoraverage 020406004080120012345 Reduction Factor1/ RNon(Rf:1)Rf: 2Rf: 3Rf: 4 Matrix : 256 , Reference Line.

8 3230thKanagawa MRI Technical MeetingYokohama City University Medical (fri)38 What happens if you change theReferenceLine?( ACS )30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)Reference Line39k-space center Self calibration ReferenceLine k-space TA 30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)Reference Line : 256 , Reduction factor : (sec)TAg-factorg-factorMAXg-factoraverag eNonGrappaNonGrappa30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)41 What happens if you change the ky30thKanagawa MRI Technical MeetingYokohama City University Medical (fri) ky42 Ts TRTs kxk kyKxmax x yFOV x 30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)Phase Over Smapling43 ky ky POS ky 12 POS 10 30thKanagawa MRI Technical MeetingYokohama City University Medical (fri) g-factorave 256256 ky 192256256512 ky 30thKanagawa MRI Technical MeetingYokohama City University Medical (fri)45 g-factorave ConventionalScanmatrix 256 256 POS SNR :112 Red-fac: :32matrix 256 256 POS SNRPI.

9 : : : :32matrix 256 256 POS 100 SNRPI: 48G-facave: : MRI Technical MeetingYokohama City University Medical (fri) GRAPPA 46 Parallel Imaigng Multi coil , GRAPPA SMASH GRAPPA GRAPPA Reduction Factor , Reference Line , ky30thKanagawa MRI Technical MeetingYokohama City University Medical (fri) 47 Parallel MRI SNR 64(8) 6 4 MRI Vol. 70(2014) 2003(1) Parallel Imaging(mSENSE, GRAPPA ) PACE Hyperecho 2003(1)vol34, k k-space (2003) MRI MRI MEDICAL VIEW