Alireza Abaei¹, Dinesh K Deelchand ², Francesco Roselli ³, and Volker Rasche ^1
1Core Facility Small Animal Imaging (CF-SANI), University of Ulm, Ulm, Germany, ²Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States, ³German Center for Neurodegenerative Diseases (DZNE), Ulm, Germany

The goal of this study was to demonstrate the feasibility to detect neurochemical differences in sub-cortical domains of the murine brain, namely upper (I-IIII) and deep (V-VI) layers. To achieve sub-microliter voxel prescription in these layers, an ultra-high field of 11.7T was used along with the single-voxel LASER sequence. Results show significantly higher taurine (13%) and phosphatidylethanolamine (36%) concentrations in the superficial cortex region compared to the deep layer, in good agreement with cellular composition of these two regions.

Nils Marc Joel Plaehn¹, Simon Mayer^1,2, Petra Albertová¹, Peter Michael Jakob¹, and Fabian Tobias Gutjahr^1
1Experimental Physics 5, University of Würzburg, Würzburg, Germany, ²Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany

Water Exchange Spectroscopy (WEX) is one of the most widely used approaches to assess the exchange rate of labile protons from a solute to water. In this work, we propose as an versatile alternative “Phase Sensitive WEX” (PS-WEX), which uses an additional RF-pulse and a fixed mixing-time delay. By exploiting the phase sensitivity of the PS-WEX pathway the dynamic range can be increased and the T1-dependence of the signal is completely reduced. This is demonstrated in simulations and phantom measurements. The fixed mixing-time reduces the influence of the T1-decay on the signal curve leading to improved fit quality.

Guodong Weng^1,2, Johannes Slotboom^1,2, and Piotr Radojewski^1,2
1Institute for Diagnostic and Interventional Neuroradiology, Support Center for Advanced Neuroimaging (SCAN), University of Bern, Bern, Switzerland, ²Translational Imaging Center, sitem-insel AG, Bern, Switzerland

Purpose: comparison of SLOW-editing and MEGA-editing for detection of 2HG in glioma-suspected patients at 7T.

Methods: EPSI-based B₀/B₀⁺ robust SLOW-editing and semiLASER-SVS/CSI-based MEGA-editing were applied in 10 patients. The edited 2HG signal at 4.01 ppm aimed to be detected with TE = 68 – 75 ms.

Results: 8 of 9 patients were identified successfully using SLOW-editing which has a higher spectral quality and success rate compared to MEGA-semiLASER. semiLASER-SVS/CSI-based MEGA-editing showed strong ghosting artifacts around 4.01ppm making 2HG-identification impossible.

Conclusions: in vivo 2HG-editing can be performed using SLOW-EPSI within 10 minutes measurement time and is the preferrable method at UHF. 

Dunja Simicic^1,2,3, Brayan Alves^1,2, Jessie Julie Mosso^1,2,3, Thanh Phong Lê^3,4, Ruud B. van Heeswijk⁵, Jana Starcukova⁶, Antoine Klauser^1,7, Bernhard Strasser⁸, Wolfgang Bogner⁸, and Cristina Cudalbu^1,2
1CIBM Center for Biomedical Imaging, Lausanne, Switzerland, ²Animal Imaging and Technology, EPFL, Lausanne, Switzerland, ³Laboratory of Functional and Metabolic Imaging, EPFL, Lausanne, Switzerland, ⁴HES-SO University of Applied Sciences and Arts Western Switzerland, Geneva School of Health Sciences, Geneva, Switzerland, ⁵Department of Diagnostic and Interventional Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland, ⁶Institute of Scientific Instruments, Czech Academy of Sciences, Brno, Czech Republic, ⁷Department of radiology and medical informatics, University of Geneva, Geneva, Switzerland, ⁸Department of Radiology, Medical University Vienna, MR Center of Excellence, Vienna, Austria

¹H-MRSI enables a simultaneous acquisition of MR-spectra from multiple spatial locations inside the brain. While ¹H-MRSI is increasingly used in the human brain, its implementation in preclinical setting is limited because of the smaller size of rodent brain. At UHF for humans, ¹H-FID-MRSI acquisitions are increasingly used (T₂ and J-evolution minimization, increased SNR). We present the first implementation of fast ¹H-FID-MRSI in the rat brain at 14.1T and exploit its potential for an increased brain coverage, reliable and accurate quantification results and metabolic maps. Our results set the grounds for a wider application of ¹H-FID-MRSI in the preclinical setting.

Michael Vaeggemose^1,2, Rolf F. Schulte³, and Christoffer Laustsen^2
1GE Healtcare, Broendby, Denmark, ²MR Research Centre, Department of Clinical Medicine, Aarhus University, Aarhus N, Denmark, ³GE Healtcare, Munich, Germany

Sodium (²³Na) MRI allows non-invasive examinations of intra-organ sodium concentrations in vivo. B1 field corrections are important determinants of the sodium signal level. However, low signal-to-noise ratio (SNR) in sodium MRI makes accurate B1 mapping in reasonable scan times challenging. The aim of this study is to evaluate Bloch-Siegert off-resonance B1 field correction of sodium images in thigh muscle, heart, kidney, and brain with the use of MRI in healthy human subjects using a 3D FLORET readout trajectory.

Zahra Shams¹, Wybe J.M. van der Kemp¹, Evita C. Wiegers¹, Jacobus J.M. Zwanenburg¹, Jannie P. Wijnen¹, and Dennis W.J. Klomp^1
1Department of Radiology, University Medical Center Utrecht, Utrecht, Netherlands

We developed a multi-echo sequence to detect phosphomonoesters (PME) and phosphodiesters (PDE), aiming for high signal-to-noise and T2-contrast to noise ratio per unit of time, with the constraint of a maximum available B1 of ~15μT. In line with MRI, the candidates were multi-echo MRSI with 180° pulses (full refocusing) and fast spin echo (FSE) with modulated variable flip angles. Multi-echo MRSI resulted in higher SNR at the same SAR level compared to a FSE with modulated refocusing flip angles. Using 9 dual-band echo pulses improved the SNR for PDE and PME more than two-fold compared to the FID signal alone.

Mark Stephan Widmaier^1,2, Song-I Lim^1,2, and Lijing Xin^1,3
1CIBM Center for Biomedical Imaging, Lausanne, Switzerland, ²Laboratory for Functional and Metabolic Imaging, EPFL, Lausanne, Switzerland, ³Animal Imaging and Technology, EPFL, Lausanne, Switzerland

In this abstract, we introduce ³¹P-MT-MRF, using a SAR efficient magnetization transfer (MT) approach. We extended the magnet resonance fingerprinting (MRF) framework to overcome obstacles of in vivo human brain ³¹P measurements. This abstract reports the reproducibility and robustness of ³¹P-MT-MRF estimations of the relaxation parameters of y-ATP and PCr as well as the chemical exchange rate k_CK on healthy volunteers in vivo in human brain at 7T. We were able to demonstrate that our method is 3 times faster as state-of-the-art MT methods [6] and estimates are bias free enabling ultra-fast k_CK measurement in 2:15 min scan time.