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In vivo brain rosette spectroscopic imaging (RSI) with LASER excitation, constant gradient strength readout, and automated LCModel quantification for all voxels
Author(s) -
Schirda Claudiu V.,
Zhao Tiejun,
Andronesi Ovidiu C.,
Lee Yoojin,
Pan Jullie W.,
Mountz James M.,
Hetherington Hoby P.,
Boada Fernando E.
Publication year - 2016
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.25896
Subject(s) - voxel , nuclear magnetic resonance , materials science , laser , nuclear medicine , biomedical engineering , optics , computer science , physics , medicine , artificial intelligence
Purpose To optimize the Rosette trajectories for high‐sensitivity in vivo brain spectroscopic imaging and reduced gradient demands. Methods Using LASER localization, a rosette based sampling scheme for in vivo brain spectroscopic imaging data on a 3 Tesla (T) system is described. The two‐dimensional (2D) and 3D rosette spectroscopic imaging (RSI) data were acquired using 20 × 20 in‐plane resolution (8 × 8 mm 2 ), and 1 (2D) ‐18 mm (1.1 cc) or 12 (3D) ‐8 mm partitions (0.5 cc voxels). The performance of the RSI acquisition was compared with a conventional spectroscopic imaging (SI) sequence using LASER localization and 2D or 3D elliptical phase encoding (ePE). Quantification of the entire RSI data set was performed using an LCModel based pipeline. Results The RSI acquisitions took 32 s for the 2D scan, and as short as 5 min for the 3D 20 × 20 × 12 scan, using a maximum gradient strengthG max = 5.8 mT / m and slew‐rateS max = 45 mT / m / ms . The Bland‐Altman agreement between RSI and ePE CSI, characterized by the 95% confidence interval for their difference (RSI‐ePE), is within 13% of the mean (RSI+ePE)/2. Compared with the 3D ePE at the same nominal resolution, the effective RSI voxel size was three times smaller while the measured signal‐to‐noise ratio sensitivity, after normalization for differences in effective size, was 43% greater. Conclusion 3D LASER‐RSI is a fast, high‐sensitivity spectroscopic imaging sequence, which can acquire medium‐to‐high resolution SI data in clinically acceptable scan times (5–10 min), with reduced stress on the gradient system. Magn Reson Med 76:380–390, 2016. © 2015 Wiley Periodicals, Inc.