Simultaneous detection of valine and lactate using MEGA-PRESS editing in pyogenic brain abscess
Autor: | Michael Dacko, Shang-Yueh Tsai, Thomas Lange, Martin Buechert, Cheng-Wen Ko, Ping-Hong Lai |
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Rok vydání: | 2016 |
Předmět: |
Healthy subjects
Biology medicine.disease 030218 nuclear medicine & medical imaging Mega press 03 medical and health sciences 0302 clinical medicine Biochemistry In vivo Valine Metabolic markers medicine Molecular Medicine Radiology Nuclear Medicine and imaging Isoleucine Abscess Brain abscess 030217 neurology & neurosurgery Spectroscopy |
Zdroj: | NMR in Biomedicine. 29:1739-1747 |
ISSN: | 0952-3480 |
Popis: | Valine and lactate have been recognized as important metabolic markers to diagnose brain abscess by means of MRS. However, in vivo unambiguous detection and quantification is hampered by macromolecular contamination. In this work, MEGA-PRESS difference editing of valine and lactate is proposed. The method is validated in vitro and applied for quantitative in vivo experiments in one healthy subject and two brain abscess patients. It is demonstrated that with this technique the overlapping lipid signal can be reduced by more than an order of magnitude and thus the robustness of valine and lactate detection in vivo can be enhanced. Quantification of the two abscess MEGA-PRESS spectra yielded valine/lactate concentration ratios of 0.10 and 0.27. These ratios agreed with the concentration ratios determined from concomitantly acquired short-TE PRESS data and were in line with literature values. The quantification accuracy of lactate (as measured with Cramer-Rao lower bounds in LCModel processing) was better for MEGA-PRESS than for short-TE PRESS in all acquired in vivo datasets. The Cramer-Rao lower bounds of valine were only better for MEGA-PRESS in one of the two abscess cases, while in the other case coediting of isoleucine confounded the quantification in the MEGA-PRESS analysis. MEGA-PRESS and short-TE PRESS should be combined for unambiguous quantification of amino acids in abscess measurements. Simultaneous valine/lactate MEGA-PRESS editing might benefit the distinction of brain abscesses from tumors, and further categorization of bacteria with reasonable sensitivity and specificity. |
Databáze: | OpenAIRE |
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