・Balanced-TFE (retrospective)・心筋形態、心機能を評価
ED volume ES volume Ejection Fraction Stroke volume Cardiac output Cardiac index
ED wall massWall motionWall thicknessWall thickening
(VED) (VES) (EF) (SV) (CO) (CI) etc
CINE
NSA 33 slice
59.4 (sec)
NSA 33 slice
59.4 (sec)
NSA 221 slice
252.4 (sec)
Clinical image (Free Breath)
gate (FFE)・R波検知後の設定範囲のデータを使用し再構成・Gatedelay,width範囲外のデータを認識できない→R波前後のデータ欠損・全てのデータを収集するまでスキャンはabortしない
・撮像時の許容するHRの範囲を決定
R-R window
Ex.
60-(60×20/100)~60+(60×10/100)
R-R window1 : 設定HRに対し早くなったHRの範囲R-R window2 : 設定HRに対し遅くなったHRの範囲
HR48~66の心拍データで画像を構成
設定HR 60
retrospective VS gate
retrospective gate
18sec / 3slice 21sec / 1slice
R-R window 30/30 R-R window 10/20
NSAを増加させFree Breathで撮像腹帯を使用 (肝臓を持ち上げるイメージで)
CINE
息止め困難
不整脈
retrospectiveでの撮像が困難→心拍をよく観察しHR,R-R windowの設定gateは撮像時間の延長&息止め回数増加→スループットの低下
T2W-BB
・Double(Triple)IR-T2W TSE・心筋の炎症、浮腫、リスク領域を評価
T2WI BB LGE
Stunnedmyocadium
High Low
Subendocardialinfraction
HighSubendocardial
High
Transmuralinfraction
HighTransmural
High
Microvascularobstraction
Iso~Low Low
TR (beat)・MR信号を得るために使用する励起RFパルスの間隔・心電同期では心拍に依存する (TR=beat×RR間隔)
HR (bpm) 2 beat (ms) 3 beat (ms)
60 2000 3000
80 1500 2250
100 1200 1800
120 1000 1500
T2WI=LongTR
Breath hold
HR 60TR 2beatdelay shortest
HR 90TR 3beatdelay shortest
916.9 (ms)
750 (ms)
RR=1000 (ms)
RR=667 (ms)
delay
delay manual longest
Trigger delay
HR (bpm)R-R (ms)
601000
70857
80750
90667
beat 2 2 2 3 2 3
Tiggerdelay(ms)
shortest 916.9 853.7798
(=48)963
(=213)750
(=83)917
(=250)
longest1900
(=900)1479
(=621)1275
(=525)1988
(=488)1117
(=450)1750
(=417)
Trigger delay
TR (beat) 3
TE (ms) 70
Half scan 0.8
profile order linear
echo space (ms) 5.1
shot duration (ms) 152
tigger delay (ms)530
(longest)
scan time (sec) 16.8
HR 75R-R 800 (ms)
Shot duration
Shot duration 100 (ms) Shot duration 120 (ms) Shot duration 150 (ms)
Shot duration 180 (ms) Shot duration 210 (ms) Shot duration 240 (ms)
*HR 80 (bpm)
Half scan併用不可=撮像時間増加
撮像時間増加
T2コントラスト低下実効TE ↓
asymmetric
Shot duration短縮
Half scan yes → no
T2コントラスト低下
Half scan
without Half scan
k-0
k-min
k-maxEx.act.TE (ms)
100TSE factor
9profile order
linearHalf scan 0.666 Half scan 0.666
+rev.linear
+ rev.linear987654321
987654321
123456789
987654321
without Half scan + linear Half scan 0.8 + linear Half scan 0.6 + linear
Half scan 0.6 + rev.linearHalf scan 0.8 + rev.linearasymmetric (es:shortest)
shot 124 (ms)BH 22.0 (sec)
shot 153 (ms)BH 18.0 (sec)
shot 252 (ms)BH 14.0 (sec)
shot 104 (ms)BH 22.0 (sec)
shot 104 (ms)BH 18.0 (sec)
shot 104 (ms)BH 14.0 (sec)
TE 89 (ms)TE 70 (ms)TE 70 (ms)
TE 70 (ms)TE 70 (ms) TE 70 (ms)
*HR 80 (bpm)
after
3
72
0.8
rev.linear
3.5
106
580(longest)
16.8
before
TR (beat) 3
TE (ms) 70
Half scan 0.8
profile order linear
echo space (ms) 5.1
shot duration (ms) 152
trigger delay (ms)530
(longest)
scan time (sec) 16.8HR 75
R-R 800 (ms)
患者の心拍に応じて異なるbeat数を調節しTR>1800 (ms)になるように
T2W-BB
心筋の動きの少ない拡張中期を狙うHR>70ではdelay=longestがbetter
TR (beat)
Shot duration
Trigger delay
delayが適切で心筋が欠けた際はHalf scan + rev.linearでShotを短く*条件により実効TEの延長有り
LGE
・3D IR-T1W TFE・心筋疾患の鑑別、予後予測
(Late Gadolinium Enhancement)
・Look LockerによるTI決定→適切なTI設定が必須*コントラスト反転の可能性・造影剤のWash outを考慮→経時的なコントラストの変化*速やかに撮像
MI DCM
心Amiloydosis心Sarcoidosis
各心拍における信号変化 (LGE)
各心拍におけるCNR
HR (bpm) TI (ms)
60 280
80 240
100 200
120 180
各TIはLook Locker上でのmyo/Null+40 (ms)を設定
各心拍における信号変化
shortest=1 beat↓
2 beatに変更SCMRによる心臓MRI(CMR)標準化プロトコールより引用http://www.scmr.jp/mri/index.html
各心拍における信号変化 (LGE)
shot interval(beat)
HR (bpm)
TI (ms)
1
60 280
80 240
100 200
120 180
2
60 320
80 300
100 260
120 240
各TIはLook Locker上でのmyo/Null+40 (ms)を設定
各shot intervalにおけるmyo-scarのCNR
RMI SR HR 90~95 (bpm)
1 (beat)SENSE 2.0
TFE factor 24
Look Locker LGE
scan time12.6 (sec)
2 (beat)SENSE 2.0
TFE factor 24
scan time22.8 (sec)
beat数による撮像時間 (LGE)
HR (bpm)scan time (sec)
1 (beat) 2 (beat)
60 20.0 38.0
80 15.0 28.5
100 12.6 22.8
120 10.5 20.0
SENSE factor&TFE factorを変更
1beatから2beatに変更→撮像時間は2倍
息止め困難
*Scan%の変動に注意*shot durationの延長
mid wall fibrosis?
no sign
PSIR
no sign
1 (beat)SENSE 2.0
TFE factor 24shot 118.2 (ms)
scan time12.6 (sec)
2 (beat)SENSE 2.3
TFE factor 31shot 147.6 (ms)
scan time15.6 (sec)
DCM SR HR 85~90 (bpm)
280 (ms)240 (ms)200 (ms) 320 (ms) 360 (ms)
Shot duration 100 (ms)+30~40 (ms)
Shot duration&TI設定
null
TI=280 (ms) TI=320 (ms)
Shot duration 150 (ms)
280 (ms)240 (ms)200 (ms) 320 (ms) 360 (ms)
+50~60 (ms)
Shot duration&TI設定
TI=280 (ms) TI=340 (ms)
null
LGE 心拍による信号の変化
高HR→Nullは短縮(T1値が長い組織ほど影響大)信号低下による影響で正常心筋の同定困難
Look Locker
LGE
高HR→縦磁化の回復が不十分→CNRの低下高HRでは2beat撮像をこの際、Look Lockerも2beatで撮像(Nullが変化)2beat撮像では撮像時間の延長→SENSE factor & TFE factorで微調整→shot延長時のTIはNullから長めに設定
LGEにおける大敵多くの心筋疾患に伴う症状
心房期外収縮 (APC)心室期外収縮 (VPC)発作性上室性頻拍 (PSVT)心房頻拍 (AT)心房粗動 (AFL)心房細動 (AF) etc
TI設定困難撮像時間の延長アーチファクト
不整脈対策
Look Locker (BH)
DCMArrythmia HR 80~100 (bpm)
BH→RT
LGE (BH)
TI=250 (ms) TI=280 (ms) TI=400 (ms)
LGE (RT)
*TIは決め打ち
RT同期不良例
①RT trigger→②R波 trigger→③データ収集呼吸が早いとデータ収集時の呼吸位相がずれやすい*軽い吸気→深い呼気になるよう呼吸指示を
①
②
③
①
②
③
TI delay
○ ×○
TI delay
Navigator
Navigatorを使用して撮像する際はRT同様に呼吸→R波の順でトリガーのかかるtrigger&trackで
RT Navi trigger&track Navi gate&track