Multivoxel 3D Proton Spectroscopy in the Brain at 1.5 Versus 3.0 T: Signal-to-Noise Ratio and Resolution Comparison
Oded Gonena,
Stephan Grubera,
Belinda S. Y. Lia,
Vladimir Mlynárika and
Ewald Mosera
a From the Fox Chase Cancer Center (O.G., B.S.Y.L.), Philadelphia, and the Institut für Medizinische Physik (S.G., V.M., E.M.), Universität Wien, Austria.
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FIG 1. Schematic of the hybrid HSI-CSI localization sequence. A 25.6- or 15-ms, 60- or 120-Hz water suppression at 1.5 or 3.0 T was followed by VOI excitation. The PRESS 5.12-ms 90° pulse also performed fourth-order HSI (HSI) along ZIS with 3 or 4.5 mT/m gradients at 1.5 or 3.0 T, respectively, followed 26.07 and 98.69 ms later by 10.24 ms SLR 180° pulses with 1 mT/m. Localization along XLR and YAP was 16 x 16 2D CSI. A 25.6- or 15-ms gaussian 180° BASING pulse was applied between the two SLR pulses for extra water suppression
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FIG 2. Corresponding (within 2–3 mm IS) axial T1-weighted MR images from the section richest in anatomic features from the same subject. Both are superimposed with the outline of the 9 x 9-cm VOIs and the real part of the corresponding 9 x 9 1H-spectra matrices. The horizontal (1.8–3.5-ppm) scale is common to both fields.
A, Examination at 1.5 T.
B, Examination at 3.0 T.
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FIG 3. Five spectra from the corresponding dashed boxes in figure 2 scaled to the same maximum NAA peak height. Note an improved Cr-Cho spectral resolution, better SNR, and flatter baseline between 2 and 3 ppm at 3.0 versus 1.5 T
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