Fast Hadamard-Encoded 7T Spectroscopic Imaging of Human Brain
<b>Background/Objectives</b>: The increased SNR available at 7T combined with fast readout trajectories enables accelerated spectroscopic imaging acquisitions for clinical applications. In this report, we evaluate the performance of a Hadamard slice encoding strategy with a 2D rosette tr...
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MDPI AG
2025-01-01
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| author | Chan Hong Moon Frank S. Lieberman Hoby P. Hetherington Jullie W. Pan |
| author_facet | Chan Hong Moon Frank S. Lieberman Hoby P. Hetherington Jullie W. Pan |
| author_sort | Chan Hong Moon |
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| description | <b>Background/Objectives</b>: The increased SNR available at 7T combined with fast readout trajectories enables accelerated spectroscopic imaging acquisitions for clinical applications. In this report, we evaluate the performance of a Hadamard slice encoding strategy with a 2D rosette trajectory for multi-slice fast spectroscopic imaging at 7T. <b>Methods</b>: Moderate-TE (~40 ms) spin echo and J-refocused polarization transfer sequences were acquired with simultaneous Hadamard multi-slice excitations and rosette in-plane encoding. The moderate spin echo sequence, which targets singlet compounds (i.e., N-acetyl aspartate, creatine, and choline), uses cascaded multi-slice RF excitation pulses to minimize the chemical shift dispersion error. The J-refocused sequence targets coupled spin systems (i.e., glutamate and myo-inositol) using simultaneous multi-slice excitation to maintain the same TE across all slices. A modified Hadamard slice encoding strategy was used to decrease the peak RF pulse amplitude of the simultaneous multi-slice excitation pulse for the J-refocused acquisition. <b>Results</b>: The accuracy of multi-slice and single-slice rosette spectroscopic imaging (RSI) is comparable to conventional Cartesian-encoded spectroscopic imaging (CSI). Spectral analyses for the J-refocused studies of glutamate and myo-inositol show that the Cramer Rao lower bounds are not significantly different between the fast RSI and conventional CSI studies. Linear regressions of creatine/N-acetyl aspartate and glutamate/N-acetyl aspartate with tissue gray matter content are consistent with literature values. <b>Conclusions</b>: With minimal gradient demands and fast acquisition times, the 2.2 min to 9 min for single- to four-slice RSI acquisitions are well tolerated by healthy subjects and tumor patients, and show results that are consistent with clinical outcomes. |
| format | Article |
| id | doaj-art-f0310b38237f4645957c75f532ec2b6e |
| institution | Kabale University |
| issn | 2379-1381 2379-139X |
| language | English |
| publishDate | 2025-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Tomography |
| spelling | doaj-art-f0310b38237f4645957c75f532ec2b6e2025-01-24T13:50:52ZengMDPI AGTomography2379-13812379-139X2025-01-01111710.3390/tomography11010007Fast Hadamard-Encoded 7T Spectroscopic Imaging of Human BrainChan Hong Moon0Frank S. Lieberman1Hoby P. Hetherington2Jullie W. Pan3MR Research Center, Department of Radiology, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, PA 15213, USAHillman Cancer Center, Department of Neurology, University of Pittsburgh, 5115 Centre Ave., Pittsburgh, PA 15232, USAResonance Research Inc., 31 Dunham Rd., Billerica, MA 01821, USANextGen Precision Health, Department of Radiology, University of Missouri Columbia, 1030 Hitt Street, Columbia, MO 65201, USA<b>Background/Objectives</b>: The increased SNR available at 7T combined with fast readout trajectories enables accelerated spectroscopic imaging acquisitions for clinical applications. In this report, we evaluate the performance of a Hadamard slice encoding strategy with a 2D rosette trajectory for multi-slice fast spectroscopic imaging at 7T. <b>Methods</b>: Moderate-TE (~40 ms) spin echo and J-refocused polarization transfer sequences were acquired with simultaneous Hadamard multi-slice excitations and rosette in-plane encoding. The moderate spin echo sequence, which targets singlet compounds (i.e., N-acetyl aspartate, creatine, and choline), uses cascaded multi-slice RF excitation pulses to minimize the chemical shift dispersion error. The J-refocused sequence targets coupled spin systems (i.e., glutamate and myo-inositol) using simultaneous multi-slice excitation to maintain the same TE across all slices. A modified Hadamard slice encoding strategy was used to decrease the peak RF pulse amplitude of the simultaneous multi-slice excitation pulse for the J-refocused acquisition. <b>Results</b>: The accuracy of multi-slice and single-slice rosette spectroscopic imaging (RSI) is comparable to conventional Cartesian-encoded spectroscopic imaging (CSI). Spectral analyses for the J-refocused studies of glutamate and myo-inositol show that the Cramer Rao lower bounds are not significantly different between the fast RSI and conventional CSI studies. Linear regressions of creatine/N-acetyl aspartate and glutamate/N-acetyl aspartate with tissue gray matter content are consistent with literature values. <b>Conclusions</b>: With minimal gradient demands and fast acquisition times, the 2.2 min to 9 min for single- to four-slice RSI acquisitions are well tolerated by healthy subjects and tumor patients, and show results that are consistent with clinical outcomes.https://www.mdpi.com/2379-139X/11/1/7rosette trajectoryfast spectroscopic imagingHadamard slice encoding7Ttumor |
| spellingShingle | Chan Hong Moon Frank S. Lieberman Hoby P. Hetherington Jullie W. Pan Fast Hadamard-Encoded 7T Spectroscopic Imaging of Human Brain Tomography rosette trajectory fast spectroscopic imaging Hadamard slice encoding 7T tumor |
| title | Fast Hadamard-Encoded 7T Spectroscopic Imaging of Human Brain |
| title_full | Fast Hadamard-Encoded 7T Spectroscopic Imaging of Human Brain |
| title_fullStr | Fast Hadamard-Encoded 7T Spectroscopic Imaging of Human Brain |
| title_full_unstemmed | Fast Hadamard-Encoded 7T Spectroscopic Imaging of Human Brain |
| title_short | Fast Hadamard-Encoded 7T Spectroscopic Imaging of Human Brain |
| title_sort | fast hadamard encoded 7t spectroscopic imaging of human brain |
| topic | rosette trajectory fast spectroscopic imaging Hadamard slice encoding 7T tumor |
| url | https://www.mdpi.com/2379-139X/11/1/7 |
| work_keys_str_mv | AT chanhongmoon fasthadamardencoded7tspectroscopicimagingofhumanbrain AT frankslieberman fasthadamardencoded7tspectroscopicimagingofhumanbrain AT hobyphetherington fasthadamardencoded7tspectroscopicimagingofhumanbrain AT julliewpan fasthadamardencoded7tspectroscopicimagingofhumanbrain |