Hyungseok Jang^1,2, Chandramouli Gadisetti³, Devasahayam Nallathamby⁴, Murali C Krishna⁴, and Alan B McMillan^1
1Radiology, University of Wisconsin, Madison, WI, United States, ²Electrical and Computer Engineering, University of Wisconsin, Madison, WI, United States, ³GenEpria Consulting Inc., Columbia, MD, United States, ⁴Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, United States

In EPR oxygen imaging, spatial and temporal resolution is challenged due to low spin densities and short relaxation times. Therefore, it is crucial to achieve accelerated imaging to allow greater flexibility in resolving spatial and temporal oxygen variations. In this study, we successfully employed a hybrid encoding scheme that greatly reduces encoding time compared with conventional SPI encoding techniques utilized in EPRI. Moreover, this new technique allows the reconstruction of images across multiple echo times from a single acquisition to enable quantification of oxygen via T₂* mapping.

Charlie Yi Wang¹, Mark Alan Griswold², and Xin Yu^2
1Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, United States, ²Radiology, Case Western Reserve University, Cleveland, Ohio, United States

In this work, we present a novel ³¹P spectroscopic magnetic resonance fingerprinting method for simultaneous measurement of T₁ and concentration of several phosphate metabolites. T₁ measurement using the current method showed good agreement with the conventional inversion-recovery method, and demonstrated increased measurement efficiency.

Vincent Boer¹, Dennis Klomp², and Peter Barker^3
1Radiology, University Medical Center Utrecht, Utrecht, Utrecht, Netherlands, ²University Medical Center Utrecht, Utrecht, Netherlands, ³Radiology, Johns Hopkins University, baltimore, Maryland, United States

A MR spectroscopy approach is presented for the simultaneous acquisition of multiple voxels. This method may speed up MRS protocols, where typically multiple locations are acquired sequentially, for example from a lesion and a contralateral brain region. High bandwidth multiband pulses and SENSE unfolding were employed to simultaneously excite and unfold MR spectra from two regions in the left and right hemisphere at 3T and 7T.

Ivan I Kirov^1,2, Shu Liu^1,2, William E Wu^1,2, Assaf Tal³, Matthew Davitz^1,2, Henry Rusinek^1,2, Joseph Herbert⁴, and Oded Gonen^1,2
1Radiology, New York University School of Medicine, New York, NY, United States, ²Center for Advanced Imaging Innovation and Research (CAI2R), New York University, New York, NY, United States, ³Chemical Physics, Weizmann Institute of Science, Israel, ⁴Neurology, New York University School of Medicine, New York, NY, United States

We studied the metabolism associated with pre-lesional tissue and non-enhancing lesions in early relapsing-remitting multiple sclerosis, using high spatial resolution proton magnetic resonance spectroscopic imaging at 3T. Absolute quantification with stringent partial volume correction was applied to measure metabolite levels in lesions under 1 cm³. Pre-lesional tissue exhibited lesion-like metabolism for the glial markers Cho, Cr and mI, but in contrast, showed higher NAA. A statistically significant correlation between the degree of T1-hypointensity and metabolism was observed for NAA, but the relationship did not hold when pre-lesional tissue was excluded from the analysis.

Tangi Roussel¹, Jens T Rosenberg^2,3, Samuel C Grant^2,3, and Lucio Frydman^1
1Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel, ²National High Magnetic Field Laboratory, Tallahassee, Florida, United States, ³Chemical & Biomedical Engineering, The Florida State University, Tallahassee, Florida, United States

The effective T1 of macromolecular resonances may be shortened using spectrally selective excitations. Relaxation Enhanced (RE) MRS exploits this in vivo, revealing apparent T1 reductions -particularly for exchanging sites. This paper presents localized spin-echo sequences based on RE MRS and dedicated to quantify in vivo metabolites resonating downfield from the water peak. RE enhanced the global spectral quality allowing us to characterize poorly assigned resonances such as ATP, Gln, GSH, NAA, PCr and estimate the changes upon stroke. This technique provides an alternative to conventional in vivo 1HMRS and allows the exploration of the downfield spectral region, potentially revealing important biomarkers.

Manoj Kumar Sarma¹, Paul Michael Macey², Rajakumar Nagarajan¹, Ravi Aysola³, and M.Albert Thomas^1
1Radiological Sciences, UCLA School of Medicine, Los angeles, CA, United States, ²School of Nursing, UCLA School of Medicine, Los angeles, CA, United States, ³Division of Pulmonary and Critical Care Medicine, UCLA School of Medicine, Los angeles, CA, United States

Patients with obstructive sleep apnea syndrome (OSAS) shows significant autonomic and neuropsychologic deficits, which may derive from damage to insular cortices and putamen, two key limbic structures that serve such functions. Here we examined neurochemical changes in the insular cortices and putamen of OSAS patients to provide indications of the nature of tissue changes using compressed sensing based 4D echo-planar J-resolved spectroscopic imaging. tCho/Cr ratio was reduced significantly in right insular cortex, and Glx/Cr, Glu/Cr ratios increased in the left insular cortex and right putamen respectively. Significantly increased GABA/Cr was found in right insular cortex with both insular cortex and putamen showing decreased tNAA, NAA and increased mI bilaterally. These findings will provide insight into structural brain changes in OSAS, and suggest possible treatment options to address common central nervous system symptoms in the sleep disorder.

Zohaib Iqbal¹, Neil E. Wilson¹, Brian L. Burns¹, Margaret A. Keller¹, and Michael Albert Thomas^1
1University of California - Los Angeles, Los Angeles, California, United States

The purpose of this study was to evaluate regional metabolite differences in perinatally HIV-infected youths using accelerated TE-averaged echo-planar Spectroscopic Imaging (accelerated TEA-EPSI), which acquires TE-averaged spectroscopic images from multiple slices in a clinically feasible scan time. The results show significantly increased Ch/Cr in the basal ganglia and increased Glu/Cr in the occipital gray regions, as well as a trend for decreased NAA/Cr in the frontal white region in the brain of HIV-infected youths when compared to that of healthy youths. This is consistent with previous findings. Overall, this study demonstrates the potential of accelerated TEA-EPSI for investigating neurological diseases.

Jullie W Pan¹, Tiejun Zhao², Victor Yushmanov¹, and Hoby Hetherington^1
1University of Pittsburgh, Pittsburgh, PA, United States, ²Siemens Medical Systems, PA, United States

A multiband spectroscopic imaging acquisition is described and applied at 3T. This method acquires simultaneous multi-slice spectroscopic images with minimal chemical shift dispersion error by virtue of a cascaded excitation spin echo sequence. The phase toggling of the excitation pulses creates an RF based k-space separation of the individual slices that can be spatially reconstructed by virtue of the sensitivity of the receive array. In conjunction with a non-selective inversion recovery, this method enables detection of abnormalities in metabolites at the cortical edge. This method is demonstrated in control and neurological patients at 3T.

Joshua Kaggie¹, Bijaya Thapa¹, Nabraj Sapkota¹, Glen Morrell¹, Neal Bangerter², Kyle Jeong¹, Xianfeng Shi³, and Eun-Kee Jeong^1
1Utah Center for Advanced Imaging Research, Radiology, University of Utah, Salt Lake City, UT, United States, ²Electrical and Computer Engineering, Brigham Young University, Provo, UT, United States, ³The Brain Institute, Psychiatry, University of Utah, Salt Lake City, UT, United States

This work demonstrates synchronous 23Na/1H dual-nuclear MR imaging using radial k-space sampling, which enabled higher SNR images than have been previously obtained with Cartesian synchronous imaging. In a scan time of only 7 minutes, both 1H and 23Na images were obtained that had only minor losses (~6%) when compared to acquiring either 1H or 23Na within separate sequences.

Christian Mirkes^1,2, G. Shajan¹, and Klaus Scheffler^1,2
1High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tuebingen, BW, Germany, ²Department for Biomedical Magnetic Resonance, University of Tübingen, Tuebingen, BW, Germany