DEPENDENCE ON T(1) OF THE ECHO AMPLITUDES FROM MULTIPLE SPIN-ECHO SEQUENCES WITH EQUIDISTANT ECHOES - SIMULATION STUDIES

被引：14

作者：

FRANSSON, A

ERICSSON, A

SPERBER, GO

机构：

[1] Department of Radiation Physics, Karolinska Institutet, University of Stockholm, Stockholm

[2] Department of Hospital Physics, University Hospital, Uppsala

[3] Department of Diagnostic Radiology, Uppsala University, Uppsala

[4] Department of Physiology and Medical Biophysics, Uppsala University, Uppsala

来源：

MAGNETIC RESONANCE IMAGING | 1993年 / 11卷 / 02期

关键词：

MAGNETIC RESONANCE IMAGING; RELAXATION TIMES; MULTIPLE ECHO SEQUENCES;

D O I：

10.1016/0730-725X(93)90024-8

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：

Transverse relaxation times were estimated from numerical simulations on spin systems using multi-echo spin-echo MRI protocols. The influence of T1 on the echo amplitudes via stimulated echo components was studied. The resulting effects on T2 estimates from the Carr-Purcell (CP), Carr-Purcell-Meiboom-Gill (CPMG), and Phase-Alternating-Phase-Shift (PHAPS; combination of CP and CPMG), multiple echo schemes were examined. Protocols with either spatially selective or nonselective refocusing pulses were studied. An intravoxel static field inhomogeneity of 0.1, 1, and 10 ppm was stimulated. The dependence on T1 of the T2 estimates was notable for T1 values below approximately 800 msec for all protocols. The PHAPS scheme provided rather accurate, but underestimated, T2 values when selective refocusing was used. With nonselective refocusing, PHAPS T2 values were overestimated and demonstrated a pronounced dependence on magnetic field inhomogeneity. In general, long T2 values were erroneous with the PHAPS protocol. The results indicate that a CPMG protocol structure provides a more robust method for T2 estimations than the PHAPS protocol.

引用

页码：197 / 205

页数：9

共 14 条

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