Gradient magnetic field measuring method using MR technique with spin echo series

článek ve sborníku ve WoS nebo Scopus

angličtina

An accurate method, suitable for measuring the time characteristics, is the method based on the MR, called the Instantaneous Frequency (IF) method [4]. The measurement can be performed on a commercial MR instrument with or without adjusted pre-emphasis compensation. This method can be used to find out the quality of the gradient magnetic fields with sufficient precision. A disadvantage of the IF method consist in the very limited time interval – up to about 2.5 ms, when we are able to acquire the MR signal for the next processing. This was the reason for the basic IF method to be extended with spin echo and thus converted to the Instantaneous Frequency of Spin Echo (IFSE) method. The spin echo was created by using the p exciting pulse. The IFSE method enables scanning the MR signal for an 18 ms time period. The third modification of the methods based on instantaneous frequency measurement is the Instantaneous Frequency of Spin Echoes Series (IFSES) method, which partially eliminates the main disadvantage of the two methods mentioned above. Its basic principle is the same; the difference is that IFSES is based on a sum of MR signals with echoes, measured at different echo times in order to extend the MR signal scanning time up to 80 ms.

RM tomography, measuring sequence, spin echo, gradient

GESCHEIDTOVÁ, E., BARTUŠEK, K.

2004

28. 3. 2004

University of Pisa

Pisa

88-8492-268-2

Progress in Electromagnetics Research

1

4

4