Yohann Mathieu-Daudé¹, Mélissa Vincent¹, Julien Valette¹, and Julien Flament^1
1Université Paris-Saclay, Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), Centre National de la Recherche Scientifique (CNRS), Molecular Imaging Research Center (MIRCen), Laboratoire des Maladies Neurodégénératives, Fontenay-aux-Roses, France

The compartmental origin of glucoCEST signal is still an ongoing debate. To address this crucial question, we proposed in this study to intravenously inject natural D-glucose and several metabolizable and non-metabolizable glucose analogues to compare their relative glucoCEST signal kinetics. The accurate measurements of glucoCEST signal kinetics provided deeper insights into the origin of glucoCEST signal and constitute a major step toward quantitative measurement of glucose metabolism using CEST imaging method. This could provide a new non-invasive tool to study brain energy metabolism defects observed in numerous neurodegenerative disorders.

Johannes Breitling¹, Andreas Korzowski¹, Neele Kempa¹, Philip S. Boyd¹, Mark E. Ladd¹, Peter Bachert¹, and Steffen Goerke^1
1Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany

In CEST-MRI, motion correction is compromised by the drastically changing image contrast at different frequency offsets and particularly at the direct water saturation. In this study, a simple extension for conventional image registration algorithms is proposed, enabling a robust and accurate motion correction of CEST-MRI data. Performance of different approaches was investigated using a ground truth dataset, generated from repeated 3D in vivo measurements at 3 T, corrupted with realistic random rigid motion patterns and noise. In comparison to the conventional image registration and a cutting-edge algorithm specifically developed for CEST-MRI, the proposed method achieved more accurate and robust results.

Yujin Jung¹, Jaeseok Park², Seong-Gi Kim², and Sung-Hong Park^1
1Department of Bio and Brain engineering, Korea Advanced Institute of Science and Technology, Daejeon, Korea, Republic of, ²Department of Global Biomedical Engineering, Sungkyunkwan University, Suwon, Korea, Republic of

CEST is a useful method to diagnose tumor or stroke, but lacks physical information such as compartments with different diffusivities. In this study, we developed a new diffusion-weighted steady-state CEST sequence using 3D EPI at 7T. The technique was tested in phantom and human brain, and the preliminary CEST-weighted apparent diffusion coefficient maps provided both CEST and diffusion information. Further study is required to clearly understand the signal source and the potential as a new biomarker.

Yiran Li¹, Danfeng Xie¹, Dushyant Kumar², Abigail Cember², Ravi Prakash Reddy Nanga², Hari Hariharan², John A. Detre³, Ravinder Reddy², and Ze Wang^1
1Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, Baltimore, MD, United States, ²Department of Radiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, United States, ³Department of Neurology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, United States

This study presents a DL based framework for correcting B0 inhomogeneity for GluCEST imaging using fewer acquisitions. Based on 3 or 5 positive offset CEST images, the proposed method can save >80% of CEST imaging acquisition time as compared to current 26 pairs of double site z-spectrum irradiations based protocol. This approach can be applied to other CEST imaging as well.

Xiao-Yong Zhang¹, Botao Zhao¹, Zhe Phillip Sun², and Yin Wu^3
1Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, China, ²Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States, ³Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China

To reduce CEST measurement’s dependence on long RF saturation duration (Ts) and relaxation delay (Td), we developed a post-processing strategy to derive the quasi-steady-state (QUASS) CEST from apparent measurements. The simulation and in-vivo experiment results show that the apparent MT and APT effects and their contrast substantially depend on Ts and Td. In comparison, the QUASS MT and APT effects and their difference between contralateral normal tissue and tumor exhibit little dependence on Ts and Td. To conclude, the QUASS CEST algorithm enables robust CEST quantification and offers a straightforward approach to standardize CEST measurements.

Ben R Dickie^1,2, Tao Jin³, Rainer Hinz⁴, Geoff JM Parker^5,6, Laura M Parkes^1,2, and Julian Matthews^1,2
1Division of Neuroscience and Experimental Psychology, Faculty of Biology Medicine and Health, The University of Manchester, Manchester, United Kingdom, ²Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Manchester, United Kingdom, ³Department of Radiology, University of Pittsburgh, Pittsburgh, PA, United States, ⁴Division of Informatics, Imaging, and Data Sciences, Faculty of Biology, Medicine, and Health, The University of Manchester, Manchester, United Kingdom, ⁵Centre for Medical Image Computing, Department of Computer Science and Department of Neuroinflammation, University College London, London, United Kingdom, ⁶Bioxydyn Ltd, Manchester, United Kingdom

Chemical-exchange spin-lock (CESL) MRI can detect uptake and clearance of intravenously administered glucose into the brain at high spatial resolution. We apply quantitative modelling to describe glucoCESL kinetics in tumour-bearing and healthy rats. Parameters relating to glucose transport (T_max, K_t, k_d), metabolism (MR_glu) and blood volume (v_b) were estimated and compared between tumour and cortical tissue.  Kinetic modelling of glucoCESL MRI data yields meaningful estimates of glucose transport and metabolism, and our modelling approach holds great promise to probe glucose transport and metabolism at high spatial resolution.

Andrew T Curtis¹ and Chad T Harris^1
1Research and Development, Synaptive Medical, Toronto, ON, Canada

A balanced steady state sequence with multiband saturation pulses was implemented on a 0.5T scanner to assess the potential for additional inhomogeneous magnetization transfer contrast generation from the higher SAR and B1+RMS limits. Volumes were acquired with B1+RMS saturation less than 15uT.  Initial results are promising with ihMT contrast scaling nearly linearly with applied B1+ as expected, achieving contrast levels of 12-16% in white matter for B1+RMS of 15uT. This linear contrast increase could directly offset losses in polarization efficiency from mid-field as compared to high field, providing an interesting application area with competitive CNR.

Daniel J. West¹, Lucilio Cordero-Grande^1,2,3, Rui P. A. G. Teixeira^1,2, Giulio Ferrazzi⁴, Joseph V. Hajnal^1,2, and Shaihan J. Malik^1,2
1Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom, ²Centre for the Developing Brain, King's College London, London, United Kingdom, ³Biomedical Image Technologies, ETSI Telecomunicación, Universidad Politécnica de Madrid & CIBER-BNN, Madrid, Spain, ⁴IRCCS San Camilo Hospital, Venice, Italy

ihMT is a promising approach for myelin imaging due to its specificity to substances with non-zero dipolar order. However, tissue model quantification requires high resolution acquisitions in excess of twenty minutes in length and so necessitates the use of motion correction methods to prevent artefacts. In this work we combine our recent MT-mediated MRF sequence with the DISORDER retrospective motion correction method. This new framework can acquire and reconstruct high resolution motion-compensated 3D time-resolved data from fingerprinting sequences. Semi‑quantitative MT and ihMT ratio maps as well as quantitative maps of tissue parameters can be obtained from the resulting images.

Maximilian Gram^1,2, Daniel Gensler^1,3, Patrick Winter^1,2, Fabian Gutjahr^2,3, Michael Seethaler^2,3, Peter Michael Jakob², and Peter Nordbeck^1,3
1Department of Internal Medicine I, University Hospital Würzburg, Würzburg, Germany, ²Experimental Physics 5, University of Würzburg, Würzburg, Germany, ³Comprehensive Heart Failure Center (CHFC), University Hospital Würzburg, Würzburg, Germany

The rapid quantification of T_1ρ using fast gradient echo sequences for data acquisition leads to a contamination of the T_1ρ relaxation pathway. Analogous to the T₁^* relaxation occurring in snapshot flash sequences, a relaxation pathway T_1ρ^* is effectively observed. As a consequence, quantification errors can arise depending on T₁ and the sequence parameters used for imaging. In this work we introduce a formalism for the description of T_1ρ^* and present a method that can be applied for the subsequent correction of study results in the field of cardiac MRI.

Casey P. Johnson^1,2, Sampada Bhave¹, Alexandra R. Armstrong¹, and Ferenc Toth^1
1Department of Veterinary Clinical Sciences, University of Minnesota, Saint Paul, MN, United States, ²Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States

Adiabatic T1ρ and T2ρ are potentially advantageous relaxation time mapping techniques for in vivo imaging of the musculoskeletal system. In this work, we compared adiabatic T1ρ and T2ρ mapping to T2 and continuous-wave T1ρ mapping in a piglet model of osteonecrosis of the femoral head. We found that adiabatic T2ρ had a robust increase in response to ischemic injury to the bone marrow, bone, and epiphyseal cartilage of the ischemic femoral head compared to the contralateral healthy femoral head. Adiabatic T2ρ may be a useful technique to detect early-stage injury in ischemic bone and joint disorders.