Andreea Hertanu^1,2, Lucas Soustelle^1,2, Arnaud Le Troter^1,2, Julie Buron^1,2,3, Julie Le Priellec³, Myriam Cayre³, Pascale Durbec³, Gopal Varma⁴, David C. Alsop⁴, Olivier M. Girard^1,2, and Guillaume Duhamel^1,2
1Aix Marseille Univ, CNRS, CRMBM, Marseille, France, ²APHM, Hôpital Universitaire Timone, CEMEREM, Marseille, France, ³Aix Marseille Univ, CNRS, IBDM, Marseille, France, ⁴Division of MR Research, Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States

We conducted a comparative study of ihMT metrics variably weighted in T_1D, with R₁ (1/T₁) and MPF (macromolecular proton fraction) for myelin specific imaging. These MRI methods were compared with histology by fluorescence microscopy using transgenic plp-GFP (proteolipid protein-Green Fluorescent Protein) mice.

Shir Filo¹, Rona Shaharabani¹, and Aviv Mezer^1
1The Edmond and Lily Safra Center for Brain Science, The Hebrew University of Jerusalem, Jerusalem, Israel

The main iron compounds, ferritin and transferrin, are distributed heterogeneously across the brain and are often implicated in neurodegenerative diseases. While quantitative MRI has been linked to brain tissue’s microstructure, non-invasive discrimination between iron forms still remains a challenge. We propose an in vivo approach for assessing brain iron forms, based on the dependency of R1 on R2*. We establish this approach in phantoms and validate it against histology. In the in vivo human brain, the dependency of R1 on R2*, rather than each parameter by itself, predicts the inhomogeneous distribution of iron-binding proteins with age and across brain regions.

Maximilian Gram^1,2, Markus Dippold², Daniel Gensler^1,3, Martin Blaimer⁴, Peter Nordbeck^1,3, and Peter Michael Jakob^2
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, ⁴Fraunhofer Institute for Integrated Circuits IIS, Würzburg, Germany

BOLD-based fMRI is currently the method of choice for the spatially resolved investigation of neuronal activity, although this technique only allows indirect measurements of activity by evaluating hemodynamic effects. Recently, a spin-lock-based technique for the direct measurement of neuro-electro-magnetic oscillations was presented, which impressively demonstrated imaging of the alpha activity. In the corresponding publication, however, elementary parameters of the spin-lock preparation were specified ad hoc. In the present work it is shown that the choice of these preparation parameters is of essential importance. For example, a clever choice of the spin-lock time can improve and stabilize the signal detection.

Kyeongseon Min¹, Sungkwon Chung², Phan Tan Toi^3,4, Jongho Lee¹, Seung‐Kyun Lee^3,4,5, and Jang-Yeon Park^3,4
1Laboratory for Imaging Science and Technology, Department of Electrical and Computer Engineering, Seoul National Univeristy, Seoul, Korea, Republic of, ²Department of Physiology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Korea, Republic of, ³Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Korea, Republic of, ⁴Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon, Korea, Republic of, ⁵Center for Neuroscience Imaging Research, Institute for Basic Science, Suwon, Korea, Republic of

In this study, the relationships between changes in cell membrane potential and MR measurements of T₁, T₂, and qMT parameters were examined using a neuroblastoma cell line (SH-SY5Y) as an in vitro model. When the membrane potential was depolarized from -37.7 mV to −7.5 mV, the changes in MR parameters were: T₁, +4.29%; T₂, +21.2%; pool size ratio (PSR), −12.4%. Contrarily, when the membrane potential was hyperpolarized to −43.0 mV, the changes in MR parameters were: T₁, −3.40%; T₂, −10.0%; PSR, +6.97%. These observations are expected to be utilized to noninvasively detect changes in the membrane potential of cells.

Phan Tan Toi^1,2,3, Hyun Jae Jang⁴, Jeehyun Kwag⁴, and Jang-Yeon Park^1,2,3
1Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Korea, Republic of, ²Center for Neuroscience Imaging Research, Institute for Basic Science, Suwon, Korea, Republic of, ³Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon, Korea, Republic of, ⁴Department of Brain and Cognitive Engineering, Korea University, Seoul, Korea, Republic of

Advanced non-invasive functional imaging methods have been widely used, but with certain limitations in either temporal or spatial information. There has long been a demand for a noninvasive imaging method capable of capturing neuronal activity with high temporal and spatial resolution. Here, we demonstrate a novel imaging method (called DIANA-fMRI) for directly detecting neuronal activity with high temporal (=5ms) and spatial (=0.22mm) resolution. DIANA-fMRI was capable of capturing sensory responses in mice at 9.4T with statistically significant signal changes (~0.1-0.2%). Temporally sequential DIANA responses were also confirmed along the thalamocortical pathway, together with further validation by electrophysiological experiments.

Dan Benjamini¹, Diego Iacono², Michal Komlosh¹, Daniel Perl², David Brody², and Peter Basser^1
1National Institute of Child Health and Human Development, Bethesda, MD, United States, ²Uniformed Services University of the Health Sciences, Bethesda, MD, United States

Can microscopic diffuse axonal injury lesions following trauma be seen non-invasively? We report that simultaneously integrating multiple MRI dimensions - T1, T2, and diffusion - can be targeted to image microscopic damage. Corpora Callosa derived from eight subjects that sustained TBI and three healthy control brain donors underwent post-mortem ex-vivo MRI at 7T. Multidimensional-, diffusion tensor-, and quantitative T1- and T2-MRI data were acquired and processed, along with corresponding pathohistological data. Although invisible using the conventional MRI modalities, multidimensional MRI provided images of the microscopic injuries, suggesting that it can be used for the detection of microscopic axonal injury.

Lingceng Ma¹, Xinran Chen¹, Jian Wu¹, Lijun Bao¹, Shuhui Cai¹, Congbo Cai¹, and Zhong Chen^1
1Department of Electronic Science, Xiamen University, Xiamen, China

A single-shot simultaneous diffusion and T₂ mapping method is developed based on overlapping-echo detachment planar imaging (DT₂M-OLED) incorporating with deep-learning reconstruction. The method makes it possible to realize simultaneous diffusion and T₂ mapping in around one hundred milliseconds for the first time, and owns an advantage in resisting motion artifacts. The accuracy of the proposed method was verified by numerical experiment and in vivo rat brain experiment. Dynamic diffusion and T₂ mapping on rat recovering from deep anesthesia was also conducted to test the capability of the proposed method in real-time imaging.

Sudhanya Chatterjee¹, Suresh Emmanuel Joel¹, Sajith Rajamani¹, Shaik Ahmed¹, Uday Patil¹, Ramesh Venkatesan¹, and Dattesh Dayanand Shanbhag^1
1GE Healthcare, Bangalore, India

We propose a method to accelerate multi-contrast MRI examination for a subject. We accelerate typically longer scans of MR exam such as FLAIR-T1, FLAIR-T2 by only acquiring its contrast information and sharing structure information from a reference scan from the same exam which is fully sampled (typically with the lowest acquisition time e.g. T2FSE). The resulting view-shared images have systematic artifacts which are then removed by a deep learning module trained on more than 200 cases. We observed high quality reconstruction (SSIM>0.9) for both healthy control and pathology cases with acceleration factors of 2x and 3x for FLAIR-T1 and FLAIR-T2.

Yongquan Ye¹, Jingyuan Lv¹, Yichen Hu¹, Zhongqi Zhang², Jian Xu¹, and Weiguo Zhang^1
1UIH America, Inc., Houston, TX, United States, ²United Imaging Healthcare, Shanghai, China

We have developed a GRE based multi-parametric MR imaging method with flexible modular design, namely MULTIPLEX. Featuring a design of dual-TR, dual-FA and multi-echo, one single MULTIPLEX scan can provide multiple imaging contrasts and quantitative mappings with 3D high resolution within clinically friendly duration, including T₁W, PDW, augmented T₁W (aT₁W), SWI and T1/T2*/PD/QSM maps, as well as optional MRA images.

Arun Joseph^1,2,3, Tobias Kober^4,5,6, and Tom Hilbert^4,5,6
1Advanced Clinical Imaging Technology, Siemens Healthcare AG, Bern, Switzerland, ²Translational Imaging Center, Sitem-Insel, Bern, Switzerland, ³Departments of Radiology and Biomedical Research, University of Bern, Bern, Switzerland, ⁴Advanced Clinical Imaging Technology, Siemens Healthcare AG, Lausanne, Switzerland, ⁵Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland, ⁶LTS5, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland

T2*-weighted imaging is an important diagnostic tool to evaluate normal and pathological tissues due to its sensitivity to iron deposition. This comes with high sensitivity to magnetic field inhomogeneities within a voxel, resulting in susceptibility artifacts. These artefacts are largely reduced at higher resolutions; high-resolution protocols however lead to clinically unfeasible scan times with multi-echo gradient echo sequences. Here, we propose a compressed sensing multi-echo GRE acquisition for 7T to obtain 0.8 mm isotropic R2* maps of the whole brain in <7 minutes and with substantially reduced artefacts. Preliminary qualitative and quantitative validations are performed on healthy subjects.