Vinod Jangid Kumar¹, Klaus Scheffler^1,2, Gisela E Hagberg^1,2, and Wolfgang Grodd^1
1Max Planck Institute for Biological Cybernetics, Tuebingen, Germany, ²Biomedical Magnetic Resonance, University Hospital and Eberhard-Karl’s University, Tuebingen, Germany

The thalamus is a central connectivity hub of the human brain that remains poorly understood concerning its anatomy. Since it houses both calcium-rich neurons and myelin-rich architecture, quantitative susceptibility mapping at the ultra-high-field may facilitate thalamic substructures' characterization. Consequently, we have acquired high-resolution QSM data at 9.4 Tesla in 21 subjects and analyzed human thalamic nuclei with respect to core and matrix neurons. We found a more substantial contribution of both diamagnetic and paramagnetic sources, like iron, myelin, and calcium, in the matrix nuclei in contrast to the relay specific core nuclei matrix nuclei.

Tom Hilbert^1,2,3, Lucas Soustelle⁴, Gian Franco Piredda^1,2,3, Thomas Troalen⁵, Stefan Sommer^6,7, Arun Joseph^8,9,10, Reto Meuli², Jean-Philippe Thiran^2,3, Guillaume Duhamel⁴, Olivier M. Girard⁴, and Tobias Kober^1,2,3
1Advanced Clinical Imaging Technology (ACIT), Siemens Healthcare, Lausanne, Switzerland, ²Department of Radiology, Lausanne University Hospital (CHUV), Lausanne, Switzerland, ³LTS5, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland, ⁴Aix Marseille Univ, CNRS, CRMBM, Marseille, France, ⁵Siemens Healthcare SAS, Saint-Denis, France, ⁶Siemens Healthcare, Zurich, Switzerland, ⁷Swiss Center for Musculoskeletal Imaging (SCMI), Balgrist Campus, Zurich, Switzerland, ⁸Advanced Clinical Imaging Technology (ACIT), Siemens Healthcare, Bern, Switzerland, ⁹Translational Imaging Center, Sitem-Insel, Bern, Switzerland, ¹⁰Departments of Radiology and Biomedical Research, University of Bern, Bern, Switzerland

A reliable and non-invasive measurement of myelin content in the brain is of high importance for neurodegenerative diseases such as multiple sclerosis. To this end, various methods have been developed over the past years with different advantages and shortcomings. In this work, six widely used methods are compared and tested for reproducibility: (i) longitudinal relaxation rate, (ii) magnetization transfer ratio, (iii) macromolecular proton fraction, (iv) inhomogeneous magnetization transfer saturation, (v) myelin water fraction, and (vi) inversion recovery at ultra-short echo time. This comparison may facilitate an informed decision on which myelin imaging techniques should be used in future studies.

Roy AM Haast¹, Sriranga Kashyap², Mohamed D Yousif¹, Dimo Ivanov², Benedikt A Poser², and Ali R Khan^1
1Centre for Functional and Metabolic Mapping, Western University, London, ON, Canada, ²Maastricht University, Maastricht, Netherlands

Intra-hippocampal perfusion patterns have remained unexplored so far but might carry important information to study disease pathogenesis. In this study we used arterial spin labeling (ASL) combined with time-of-flight angiography acquired at 7T to delineate perfusion and the effects of vascularisation patterns across the hippocampal subfields. We found that (i) imaging hippocampal perfusion in vivo is feasible using ASL at 7T, (ii) perfusion could serve as biomarker to differentiate hippocampal subfields, but that (iii) the impact of the dense macrovascular network varies based on characteristics such as distance and diameter.

Omer Faruk Gulban^1,2, Saskia Bollman³, Renzo Huber¹, Kendrick Kay⁴, Benedikt Poser¹, Federico De Martino¹, and Dimo Ivanov^1
1Department of Cognitive Neuroscience , Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands, ²Brain Innovation, Maastricht, Netherlands, ³Centre for Advanced Imaging, The University of Queensland, Brisbane, Australia, ⁴Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States

We measured in vivo human brain T₂^* values using 7T MRI at 0.35 × 0.35 × 0.35 mm³. We simultaneously targeted calcarine sulcus and Heschl’s gyrus. Our results show that gray matter T₂^* varies up to 15 ms (global range being mostly in between 25-45 ms) from deep to superficial layers. The stria of Gennari shows up as a major reduction of T₂^* within calcarine sulcus. However, a similar layering is not visible within Heschl’s gyrus. B₀ alignment effects seem to be not as strong as the biological tissue composition effects that are observed across the visual and auditory regions.

Zhengwang Wu¹, Yuchen Pei¹, Ya Wang¹, Tao Zhong¹, Fenqiang Zhao¹, Li Wang¹, He Zhang², and Gang Li^1
1Department of Radiology and BRIC, UNC-Chapel Hill, Chapel Hill, NC, United States, ²Department of Radiology, Obstetrics and Gynecology Hospital, Fu Dan University, Shanghai, China

We constructed a set of temporally-densely sampled cortical surface atlases for the fetal brain from 22 to 36 gestational weeks. This 4D fetal cortical surface atlas, which will be released to the public soon, together with the UNC 4D Infant Cortical Surface Atlas provide the longest temporally-consistent atlas chain from the prenatal 22 gestational weeks to the postnatal 7 years of age. 

Allen A Champagne^1,2 and Alex A Bhogal^3
1School of Medicine, Queen's University, Kingston, ON, Canada, ²Center for Neuroscience Studies, Queen's University, Kingston, ON, Canada, ³Radiology, University Medical Center Utrecht, Utrecht, Netherlands

Cerebrovascular reactivity (CVR) mapping is finding increasing clinical applications as a non-invasive probe for vascular health. Untangling physiological factors driving differences in temporal delays within the tissue-specific CVR response can help better understand the pathophysiological mechanisms associated with vascular impairments. Here, we combine hypercapnic and hyperoxic respiratory challenges with high resolution 7T MR-based imaging to gather insight about differences in the temporal response to CVR between grey- and white-matter tissues. Our findings support the hypothesis that differences in the physiological response to hypercapnia may be determined by compounding effects related to CO₂ sensitivity and blood flow (re)distribution.

Weimin Zhang¹, Chenyu He¹, Xiaojun Guan², Xiaojun Xu², Hongjiang Wei³, and Yuyao Zhang^1,4,5
1School of Information Science and Technology, ShanghaiTech University, Shanghai, China, ²Department of Radiology, The Second Affiliated Hospital, Zhejiang, China, ³Institute for Medical Imaging Technology, School of Biomedical Engineering, Shanghai, China, ⁴Shanghai Engineering Research Center of Intelligent Vision and Imaging, ShanghaiTech University, Shanghai, China, ⁵iHuman Institute, ShanghaiTech University, Shanghai, China

The thalamus is a relay station that routed and modulated brain signals from the deep gray-matter to the cortex. It can be divided into sub-nuclei that are highly related to various neurological disorders. However, those sub-nuclei are indistinguishable in standard T1 or T2 weighted MRI. We present a multi-atlas thalamic sub-nucleus parcellation framework guided by 7T QSM image, which provides histologically consistent contrast in thalamic sub-nuclei. Combining with a set of 3T QSM images, the thalamic parcellation in 7T image space is transferred into the 3T atlas space as a 64 sub-nucleus parcellation map.

Hyunyeol Lee¹ and Felix W Wehrli^1
1Radiology, University of Pennsylvania, Philadelphia, PA, United States

Quantitative BOLD (qBOLD) seeks to quantify voxel-wise deoxygenated blood volume (DBV) and venous blood oxygen saturation (Y_v) based on R₂′-sensitive signal acquisitions. A complication in qBOLD is the separation of signal contributions from R₂, and R₂′ from heme and non-heme iron sources, particularly in the deep brain structures. Here, we develop a new 3D qBOLD mapping method by tackling the confounding factors based on preliminary estimates of R₂, R₂’, and voxel susceptibility, along with cerebral venous blood volume. Results suggest feasibility of the proposed, prior-based qBOLD method for 3D mapping of DBV and Y_v across the entire brain.

Sen Ma¹, Tianle Cao^1,2, Nan Wang¹, Anthony G. Christodoulou¹, Zhaoyang Fan¹, Yibin Xie¹, and Debiao Li^1
1Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States, ²Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, United States

We propose an integrated and efficient solution to clinical whole-brain MRI in a single 10min sequence, producing co-registered, quantitative PD, T1, T2, T1ρ, T2*, QSM, and ΔB0 information plus clinically adopted, synthetic contrast-weighted images including PDw, T1w, T2w, T2*w, FLAIR, SWI, true-SWI, mIP, and true-SWI mIP simultaneously. Quantitative maps and contrast-weighted images are generated with good image quality and contrasts. Quantitative measurements agree with literature values. This method has the clinical potential for comprehensive risk assessment and disease evaluation, combining early detection, diagnosis, tissue characterization, and treatment monitoring of various brain diseases.

Yongxian Qian¹, Karthik Lakshmanan¹, Anli Liu², Yvonne W. Lui¹, and Fernando E. Boada^1
1Radiology, New York University, New York, NY, United States, ²Neurology, New York University, New York, NY, United States

Neurons are firing when emitting action potentials to communicate with each other. Action potentials generate fast electric currents (~2ms duration) across membrane and slow ones (~10–100ms) at postsynaptic side. These currents generate electric and magnetic fields detectable by scalp EEG and MEG, respectively. They detect the fields relatively far away (~20mm) from firing sources and are only sensitive to slow, easily-synchronized postsynaptic currents. Here we propose a new approach termed as magnetic resonance recording of local neuronal firings (mrLNF) that has a very high temporal resolution (0.25ms) and can non-invasively detect fast and slow neuronal currents at the firing sources.