Please use this identifier to cite or link to this item: http://ahro.austin.org.au/austinjspui/handle/1/9883
Title: Physiologic variability of single-voxel proton MR spectroscopic measurements at 3T.
Authors: Wellard, R Mark;Briellmann, Regula S;Jennings, Claire;Jackson, Graeme D
Affiliation: Brain Research Institute, Austin Health, Melbourne, Australia.
Issue Date: 1-Mar-2005
Citation: Ajnr. American Journal of Neuroradiology; 26(3): 585-90
Abstract: Physiologic and scanner variability of proton MR spectroscopy (MRS) measurements can limit the detection of subtle metabolite fluctuations. We assessed the variability of such measurements at 3T and compared two methods to obtain absolute concentrations.Variability over 14 days was assessed with short-echo, single-voxel proton MRS in 14 control subjects and in a phantom containing 50 mmol/L N-acetylaspartate (NAA). Spectra were analyzed by using LCModel, scaling factors determined with both the calibration phantom (CP), and water peak intensity (WP) methods. Relative (reflecting the systematic drift) and absolute variability (reflecting the magnitude of scanner variability) was determined.For the phantom, initial (49 +/- 1.7 mmol/L) and second measurements (50 +/- 1.6 mmol/L) showed similar results, with small variability (relative, -0.6 +/- 1.5 mmol/L; absolute, 1.1 +/- 1.1 mmol/L). Control subjects had no systematic difference between the two scans for any measurement. Absolute variabilities in the temporal lobe for total NAA (NAA+NAAG) were 13% (CP) and 11% (WP). The largest variability (29%) was found for glutamate-glutamine (29%) with the CP method, and for myo-inositol with the WP method (28%). Absolute variability was smaller for the frontal lobe measurements (total NAA 7% and overall 6-18% for CP; total NAA 6% and overall 5-19% for WP). No significant difference was observed between the two methods.Physiologic variability is the major source of measurement variability and accounts for 12% of the variability in temporal lobe total NAA. Therefore, total NAA variations must clearly exceed this before they can reliably be attributed to an effect of disease.
Internal ID Number: 15760870
URI: http://ahro.austin.org.au/austinjspui/handle/1/9883
URL: http://www.ncbi.nlm.nih.gov/pubmed/15760870
Type: Journal Article
Subjects: Adult
Aspartic Acid.analogs & derivatives.metabolism
Brain.metabolism
Calibration
Female
Frontal Lobe.metabolism
Glutamic Acid.metabolism
Glutamine.metabolism
Humans
Inositol.metabolism
Magnetic Resonance Spectroscopy
Male
Models, Biological
Osmolar Concentration
Phantoms, Imaging
Reference Values
Reproducibility of Results
Temporal Lobe.metabolism
Time Factors
Appears in Collections:Journal articles

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