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Integrated data acquisition and processing to determine metabolite contents, relaxation times, and macromolecule baseline in single examinations of individual subjects
Author(s) -
Kreis Roland,
Slotboom Johannes,
Hofmann Lucie,
Boesch Chris
Publication year - 2005
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.20673
Subject(s) - baseline (sea) , t2 relaxation , metabolite , macromolecule , relaxation (psychology) , nuclear magnetic resonance , chemistry , data acquisition , computer science , medicine , magnetic resonance imaging , biology , biochemistry , physics , radiology , fishery , operating system
Absolute quantitation of clinical 1 H‐MR spectra is virtually always incomplete for single subjects because the separate determination of spectrum, baseline, and transverse and longitudinal relaxation times in single subjects is prohibitively long. Integrated Processing and Acquisition of Data (IPAD) based on a combined 2‐dimensional experimental and fitting strategy is suggested to substantially improve the information content from a given measurement time. A series of localized saturation‐recovery spectra was recorded and combined with 2‐dimensional prior‐knowledge fitting to simultaneously determine metabolite T 1 (from analysis of the saturation‐recovery time course), metabolite T 2 (from lineshape analysis based on metabolite and water peak shapes), macromolecular baseline (based on T 1 differences and analysis of the saturation‐recovery time course), and metabolite concentrations (using prior knowledge fitting and conventional procedures of absolute standardization). The procedure was tested on metabolite solutions and applied in 25 subjects (15–78 years old). Metabolite content was comparable to previously found values. Interindividual variation was larger than intraindividual variation in repeated spectra for metabolite content as well as for some relaxation times. Relaxation times were different for various metabolite groups. Parts of the interindividual variation could be explained by significant age dependence of relaxation times. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.