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AJNR - American Journal of Neuroradiology

Published ahead of print on January 31, 2008
doi: 10.3174/ajnr.A0854

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Low-Grade Glioma: Correlation of Short Echo Time ¹H-MR Spectroscopy with ²³Na MR Imaging

R. Bartha^a,b, J.F. Megyesi^c and C.J. Watling^d

^a Laboratory for Functional Magnetic Resonance Research, Robarts Research Institute, London, Ontario, Canada
^b Department of Diagnostic Radiology and Nuclear Medicine, University of Western Ontario, London, Ontario, Canada
^c Division of Neurosurgery, Department of Clinical Neurological Sciences and Department of Pathology, London Health Sciences Centre, University of Western Ontario, London, Ontario, Canada
^d Departments of Clinical Neurological Sciences and Oncology, University of Western Ontario, London, Ontario, Canada

View larger version (70K): [in this window] [in a new window]   Fig 1. Transverse T1-weighted (A; TI/TR/TE = 500/9.5/5 ms), 23Na (B; TR/TE = 25/3.8 ms), and FSE (C; TR/TE = 4500/15 ms) 4T MR images of a typical low-grade glioma in the same patient. The T1-weighted image has a 10-mm section thickness corresponding with the 23Na image thickness. The white arrow identifies the low-grade glioma in each image. White boxes outline tissue regions in tumor (A) and on the contralateral side (B) studied by spectroscopy.

View larger version (18K): [in this window] [in a new window]   Fig 2. White matter MR spectrum (center gray line) with fit (center black line) superimposed. Individual metabolite components are shown beneath, along with the fit residual (top).

View larger version (23K): [in this window] [in a new window]   Fig 3. A, A representative LASER (TR/TE = 2200/46 ms) spectrum (including metabolite and macromolecule components) from 1 patient with low-grade glioma. The corresponding metabolite nulled macromolecule spectrum (B) is subtracted from a fully processed spectrum (A). C, The resultant spectrum after water removal demonstrates the efficacy of the macromolecule removal. D, A second dataset acquired in a different subject is also provided. Spectra have been line broadened by a 2-Hz Lorentzian filter for display.

View larger version (27K): [in this window] [in a new window]   Fig 4. Scatter plot of individual metabolite levels (millimoles per liter of VOI) for NAA (A), Cr (B), Cho (C), Glu (D), mIns (E), and percentage of sodium signal intensity (F) in grade II glioma and on the contralateral side are shown along with horizontal lines indicating the metabolite averages. Data from a reference region of homogeneous white matter are also included from a previous study.19 The sodium signal intensity in arbitrary units is reported for grade 2 glioma and from the contralateral side. Asterisks indicate significant differences between grade 2 glioma and control (NAA, Glu, mIns, and sodium).

View larger version (18K): [in this window] [in a new window]   Fig 5. Correlation of pooled NAA with Glu (A) and mIns (B) and of percentage of sodium signal intensity normalized to white matter (WM) with NAA (C) and Glu (D). Linear regression lines are superimposed. Details of the correlation results are described in the text.

View larger version (10K): [in this window] [in a new window]   Fig 6. Metabolite ratios for NAA/Cho (A), NAA/mIns (B), and NAA/23Na (C). Asterisks represent significantly lower value compared with control.