Image Processing Reference
In-Depth Information
11
Principles of MR
Spectroscopy and
Chemical Shift Imaging
Uwe Klose and Filip Jiru
CONTENTS
11.1
Introduction ...........................................................................................369
11.2
SVS ........................................................................................................370
11.2.1
PRESS and STEAM ...............................................................371
11.2.2
Artifacts in SVS ......................................................................377
11.2.3
Water Suppression...................................................................380
11.2.4
Coupling Effects in SVS.........................................................384
11.3
Principles of CSI ...................................................................................386
Basic Principles.......................................................................386
11.3.2 Avoiding Undesired Excitations .............................................389
11.3.3 Reconstruction of CSI Data....................................................392
11.3.4 K-space Weighting Techniques...............................................397
11.3.5 CSI PreProcessing...................................................................400
11.3.6 Display of the CSI Data .........................................................401
11.3.7 Comparison of SVS and CSI Techniques ..............................404
11.4 Differences in Sequences for Measurements
with Nonproton Nuclei..........................................................................405
References .........................................................................................................406
11.3.1
11.1
INTRODUCTION
Most of the clinical magnetic resonance (MR) scanners being used mainly for
MR imaging allow additionally the acquisition of MR spectra. In MR spectros-
copy, information about the distribution of chemical compounds in a chosen
volume of interest can be obtained, and signals from various nuclei present in
the compounds can be observed. Feasible nuclei for
measurements on
patients are hydrogen-1, phosphorus-31, carbon-13, and fluorine-19. The most
frequently used nucleus for
in vivo
MR spectroscopy is hydrogen-1. This nucleus
consists only of one proton, and this measurement technique is therefore often
in vivo
369
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