ANALYSIS OF ON-RESONANCE AND OFF-RESONANCE MAGNETIZATION-TRANSFER TECHNIQUES

被引:41
作者
HUA, JM
HURST, GC
机构
[1] CASE WESTERN RESERVE UNIV,METROHLTH MED CTR,DEPT RADIOL,CLEVELAND,OH 44109
[2] CASE WESTERN RESERVE UNIV,DEPT CHEM,CLEVELAND,OH 44109
来源
JMRI-JOURNAL OF MAGNETIC RESONANCE IMAGING | 1995年 / 5卷 / 01期
关键词
IMAGE PROCESSING; MAGNETIZATION TRANSFER CONTRAST; PULSE SEQUENCES;
D O I
10.1002/jmri.1880050120
中图分类号
R8 [特种医学]; R445 [影像诊断学];
学科分类号
1002 ; 100207 ; 1009 ;
摘要
Three methods of performing magnetization transfer (MT) MR imaging are analyzed: (a) off-resonance continuous wave, (b) off-resonance shaped pulses, and (c) on-resonance binomial pulses. With two-pool Bloch-model simulations, signal levels from ''MT active'' spin systems were calculated, with reference to direct saturation of ''MT inactive'' systems, allowing calculation of contrast due to MT, Simulations demonstrate several trends with variation of excitation amplitude and offset frequency for the off-resonance methods and with variation of excitation amplitude and pulse shape ''order'' for binomial pulses. The simulations show that nominally optimized versions of each of these approaches provide essentially equivalent contrast at a given level of applied MT power, contrary to previous claims. Experiments with an MT-inactive phantom, with a whole-body system, show results with off-resonance pulses to be in good agreement with simulations, whereas binomial-pulse experiments show anomalously large direct saturation,
引用
收藏
页码:113 / 120
页数:8
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