Data Processing Methods in MRS - Advance Image Processing in Magnetic Resonance Imaging - page 402

12

Data Processing
Methods in MRS

Luca T. Mainardi and Sergio Cerutti

CONTENTS

12.1 Introduction............................................................................................411
12.2 Extracting Information from the FID Signal ........................................413
12.3 Time-Domain Preprocessing .................................................................416
12.3.1 Zero Filling .............................................................................416
12.3.2 Windowing ..............................................................................416
12.3.3 Removal of Undesired Resonance..........................................417
12.4 Frequency-Domain Methods .................................................................418
12.5 Time-Domain Methods ..........................................................................419
12.6 Conclusions............................................................................................423
References .........................................................................................................423

12.1 INTRODUCTION

In the last 20 years, there has been an increasing interest in magnetic resonance
spectroscopy (MRS) in different fields ranging from analytical chemistry through
material sciences to biomedical applications. In particular, the well-known suc-
cess and the widespread application of MRS techniques in biomedical research
and medical practice have been supported by a number of inherent advantages
of this technique: MRS performs repetitive, nondestructive measurements of
metabolic processes

in situ as they proceed in their own environment and it allows

the extraction of valuable information on the physiological and patholog-

ical state of human tissues in different organs [1].
It is known that the metabolic information contained in the magnetic
resonance (MR) signal (the free induction decay [FID] signal) is apparent in
its spectrum. In fact, in MRS spectra, the different compounds appear as
different resonance peaks: the position of resonance identifies the specific
compound, peak line width indicates the transverse relaxation time of the
nucleus (an index linked to the mobility of the molecule) and, finally, the total

in vivo

411