MRI MRI 3 123 MRIMRI 20 1897 1911 1932 10 15 m spin 12 C 16 O 1 H 13 C 14 N 19 F µmagnetom 2-1-1
2-1-1 MB 0 µ B 0 z /B 0 precession 2-1-2 ωγ γ ω=γβ 0 ωγ µ τ γ γ
γ γ ω 2-1-2 2 2 2 2 2-1-3 2 0.5T 100 100 +3 1.5 T 100 100 +9 2-1-4 2-1-3M 0
M 0 2-1-3M 0 2-1-4 2-1-5 X-CTX MRM 0 M 0 MR M 0 M 0 2-1-5MRMR MRM 0 M 0
MR 0.3T 0.3T 1.0T 1.0T M 0 signal noise ratio, SNR EEG EEG EEG weighted-imaging M 0 M 0
M 0 M 0 M 0 B 0 B 1 B 1 M 0 B M 0 B 2-1-8 2 2-1-8 1 2-1-8B 1 B 1 BoB 1 M 0 M 0 XY MxyZRF M 0 BMzMxy 2-1-9 M 0 XY
M 1 MXY 2-1-9M Z M XY M 0 Mxy MzB 1 RFRFM Z M XY M 0 B 0 Z(flip angle, FA) RFRFM 0 1B 1 2RFT RFMoRF 90180 2-1-10 M 0 B 1 2-1-10RFM 0 RF,MoZXY B 1 RF MR B 1 2-1-11 RF
RF 2 RF 2-1-11ω 0 B 1 RF tw1/tw 1/twXtw1/tw RFB 1 2-1-12 RFRF B 1 RF tw 1/tw RFRF RF 2-1-12 RF
M 0 M 0 longitudinal relaxationm z RFRFM 0 90 M Z M Z M 0 T 1 T 1 90 M Z 0 0.63M 0 ( 2-1-13 )M Z 0 M 0 4 5 T 1 2-1-13T 1 -RF M 0 XY M Z 90 RFRF -(spin-lattice relaxation) T 1 1.5T T 1 260msT 1 4000 mst 1 WI T 1 920ms T 1 790ms
3 T 1 WIT 1 ( 2-1-13 2-1-14 ) 2-1-14T 1 WI T 1 T 1 T 1 WI 2-1-2 1.5T 1.5TT 1 ms 790 920 4000 1200 490 830 870 260 582 980 400 1150 1000 1400 582 M 0 XYM XY 90 2-1-15 90 XY 2-1-8 2-1-3 90 XY 2-1-16
XYM XY - transverse relaxation,spin-spin relaxationm XY Mxy 37%transverse relaxation timet 2 1.5T (T 2 80ms)(T 2 2000ms 2-1-17 2-1-15 RF
2-1-16 Hb ω=γ (B+Ba), A B 90XY MaMb Ma Mb Mxy 2-1-17T 2 2-1-31.5T 1.5TT 2 ms 90 100 250 250 40 80 50~60 80 140 95 140 94 86 170
72 T 2 T 2 8 T2 T2 T2 2-1-19 T 2 M S /M 0 1.0 1.0 0.3 0.2 0.61 0.58 1.0 0.2 0.9 0.25 M S M t M S M t MRI 1T 2 *
MR T 2 * T 2 * 2 * T 2 * 2 * 2 * T 2 *T 2 rant 2 fixt 2 T 2 MRMR echo time TE MR 2-1-20 T 2 T 2 T 2 1.5TT 2 2000msT 2 90ms T 2 MR MRT 2 TE T2 MR 2-1-4 T 2 TET 2 MR T 2 MR 2-1-20 2-1-20TEMRSETR3000 mste 4585125 165205265 mste 200msTE T 2 T 2 T 2
MR J MRI 2-1-21 2-1-21 1H-MRS 4.70ppm 1.33ppm 1.5T 63.9MHz 63.9MH220Hz (Chemical shift)ppm MRIT 1 T 2 MRSMR ω= Φ B ΦB 3.4ppm 1.0T
3.442.576 MHz=144.76Hz 1.5T 217Hz J coupling constantjhz JJ -JJ CH 2 CH 7HzCH 2 CH 3 25Hz 2-1-22 2-1-22 7Hz 20msJ JSET 2 80ms,1.5T, TSEESP 20ms 600W 70% (specific absorption ratesar) W/kg 1 3839 40 SAR SAR SAR SAR=P -(P +P +ABR) PPP ABR(absorption rate) ABRABR
10 8W/kgYY0319-2000 M 0 M 0 M 0 - MR - J- 3.0T RF B 0 ωb 0 42.576MHzRF M 0 T 1 T 2 M 0
1973 Lauterbur XYZ G X G Y G Z MR MR Gz Gx Gy 2-2-1 2-2-1 xyz 3 Z Y X MR 2-2-2 2-2-2
slew rate Gmax Trising mt/m ms T/m sgmax 25mT/m, Trising 300ms 83mT/m ms Trising 200ms 125mT/m ms G Z G Z 2-2-3 2 2-2-3RF G MR RF MR 2-2-4 a b 2 1. ab abω a >ω b 2. MM a> M bmt 1.5T 1/100M
2-2-4 G a a Ba b Bb Ba>Bb g a h b ωm 0 2-2-4 aa gz ω 1 -ω 2 ω 1 -ω 2 RFa am 0 M 0 a M a M g bcdb RFbM b M h RF M 0 2-2-3 RF RF 1 ωγ ωγ ω ωωγ ω
ωγ ω Gz RF th=1/γ Gz T 0 ) 223 thγ 42.6MHz/TT 0 RF Gz RF 2-2-5 RF RF 2-2-5 RF T 0 2-2-6 2-2-6T 0 T 0 T 0 T 0 T 0
2-2-7 2-2-7 RF G 3 2-2-8 RF RF M 0 GyGx Gx 2-2-9 Fourier transform, FT 2 - FT 2 FTMR
2-2-9 FT 2 G z RF 2-2-10, XMRX MR 2-2-1FTX MR 2-2-10 MRS1 G X X ABMR XYMR MR
ω x =γ X G x 224 X MR M 0 2-2-11 2-2-11 MR. MR MRMR MR 2-2-12 MR FT M X 256 128 MR Band width,bw 2-2-12 Bw=1/t 225
2-2-12 MR t t MRIM 0 field of view, FOV(G X ) 1/tN X FOV x =1/γ 226 M 0 Gy G Z G X X MRMR MR Larttberg MR 2003 2-2-13FIDRF
Yt 1,X t 2 XMR Larttberg Gz Gx Gy 2-2-13 Gy Y GyGy ( 2-2-14)Gy Gz Gx 2-2-14 SPIN WARP-Gy Gy Gx Gy Gy Φ y =360 o γ 227 Gy Gy Gy 2-2-14 MRI ( 2-2-15 ) Gy MR Gy Gy 2-2-15Gy MR Gy Ny MR
K MRI Y FT 2-2-16 1-4-16 FT MR X MR Y MR MRI FOVy field of view, FOVy Gy Gy 1/t Ny FOV y =1/γ 2.2.8 GzGx Gy FT MR 2-2-17
2-2-17 2 AB ω=γb, ωa ωb RF 2-2-18 2-2-18RFZ RFABXYGz B A >B B ABω A >ω B AB MR Gω A <ω B AB, GMN 3 FE PC M 0 RFGth=1/γ G T 0 ) FOVX FOV x =1/γ PC