Sagar Buch¹, Ying Wang², Pavan K. Jella¹, Min-Gyu Park³, Yongsheng Chen^1,4, Jiani Hu¹, Yulin Ge⁵, Kamran Shah¹, and E. Mark Haacke^1,2
1Department of Radiology, Wayne State University, Detroit, MI, United States, ²Magnetic Resonance Innovations, Inc., Detroit, MI, United States, ³Department of Neurology, Pusan National University School of Medicine, Yangsan, Korea, Republic of, ⁴Department of Neurology, Wayne State University, Detroit, MI, United States, ⁵Department of Radiology, New York University School of Medicine, New York, NY, United States

We demonstrate the utility of low dose Ferumoxytol in microvasculature imaging of the midbrain using susceptibility weighted imaging (SWI). Mapping the brain’s vasculature has implications for understanding the etiology of many neurovascular and neurodegenerative diseases such as Parkinson’s disease. By administering this strongly paramagnetic agent, SWI was able to visualize both arteries and veins; and its sensitivity to detect sub-voxel vessels increased tremendously. However, the use of Ferumoxytol exacerbates the signal loss of large vessels, confounding the ability to visualize nearby smaller vessels. Hence, we propose the use of multiple time point SWI to effectively see through the blooming artifacts. 

Falk Luesebrink^1,2, Mattern Hendrik², Renat Yakupov³, Steffen Oeltze-Jafra^1,4, and Oliver Speck^2,3,4,5
1Medicine & Digitalization, Otto-von-Guericke University, Magdeburg, Germany, ²Biomedical Magnetic Resonance, Otto-von-Guericke University, Magdeburg, Germany, ³German Center for Neurodegenerative Diseases, Magdeburg, Germany, ⁴Center for Behavioral Brain Sciences, Magdeburg, Germany, ⁵Leibniz Institute for Neurobiolgoy, Magdeburg, Germany

Here, we present an extension to our previously published T₁-weighted dataset with an ultrahigh isotropic resolution of 250 µm, consisting of multiple additional contrasts. Included are up to 150 µm ToF, an updated 250 µm MPRAGE, 330 µm QSM, up to 450 µm T₂-weighted SPACE, 750 µm MPM, 800 µm DTI, one hour continuous rs-fMRI as well as more than 130 MPRAGE volumes collected over 10 years (with varying spatial resolution between 450 µm and 1 mm). All data were acquired on the same 7 T scanner and of the same subject. Basic pre-processing of all data were conducted.

Yoshitaka Bito¹, Kuniaki Harada¹, Hisaaki Ochi², and Kohsuke Kudo^3
1Healthcare Business Unit, Hitachi, Ltd., Tokyo, Japan, ²Research and Development Group, Hitachi, Ltd., Tokyo, Japan, ³Department of Diagnostic Imaging, Hokkaido University Graduate School of Medicine, Sapporo, Japan

Cerebrospinal fluid (CSF) plays an important role in the clearance system of the brain. Low b-value DTI is reported to be useful for observing the CSF flow; however, the precise flow property observed by low b-value DTI has not been fully investigated. We proposed a mathematical framework of low b-value DTI for analyzing a pseudo-random flow and applied this framework to investigation into CSF. Measured DTI shows high and anisotropic diffusivity, representing large variance of flow velocity, in some segments of CSF. It demonstrates that low b-value DTI can be used for analyzing pseudo-random flow of CSF.

Wei Liu¹ and Kun Zhou^1
1Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen, China

As commonly used for intracranial vasculature, 3D TOF usually requires long acquisition time. In this study, we implemented a 3D-iEPI sequence with partial flow compensation, combined with partial Fourier acquisition to further reduce the flow artifacts. In specific, each interleave is sequentially acquired twice with alternating readout polarities to reduce the systematic inconsistencies between odd and even echoes. We explored the feasibility of such a sequence for fast intracranial TOF-MRA and demonstrated that the proposed sequence can reduce the acquisition time by approximately a factor of 2 with comparable vasculature depiction to 3D-GRE, which is promising for future applications.

Jacob-Jan Sloots¹, Alberto De Luca¹, Geert Jan Biessels², and Jaco Zwanenburg^1
1Radiology, University Medical Center Utrecht, Utrecht, Netherlands, ²Neurology, University Medical Center Utrecht, Utrecht, Netherlands

The heartbeat induces microvascular blood volume pulsations and subsequent tissue deformations in the brain. Although subtle (typically <1%), these deformations are highly relevant as they accelerate clearance of brain waste products. Moreover, they enable non-invasive assessment of mechanical tissue properties. We developed a sensitive MRI technique with full brain coverage for voxelwise quantification of the cardiac-induced brain tissue strain tensor with 3mm isotropic resolution, based on displacement encoding with stimulated echoes (DENSE). We visualize the strain tensor similar to diffusion tensor imaging. Strain tensor imaging opens a window on brain tissue mechanics and physiological blood volume dynamics in the brain.

Toshiaki Taoka^1,2, Rintaro Ito^1,2, Rei Nakamichi², Toshiki Nakane², Hisashi Kawai², and Shinji Naganawa^2
1Department of Innovative Biomedical Visualization, Nagoya University, Nagoya, Japan, ²Department of Radiology, Nagoya University, Nagoya, Japan

To visualize the dynamics of cerebrospinal fluid (CSF) motion within the cranium, we evaluated the distribution of the motion-related signal dephasing by CSF on a Multi b-value Diffusion-weighted image Diphase Map (MbDDM). The MbDDM indicated that CSF motion was prominent in areas that included the ventral portion of the posterior fossa, the suprasellar cistern and the Sylvian fissure. Whereas, CSF motion was less in the lateral ventricles and the parietal subarachnoid space, casting doubt on the classical model of CSF dynamics. 

Kun Qian¹, Tomoki Arichi¹, Jonathan Eden², Sofia Dall'Orso², Rui Pedro A G Teixeira³, Kawal Rhode³, Mark Neil⁴, Etienne Burdet², A David Edwards¹, and Jo V Hajnal^1
1Centre for the Developing Brain, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom, ²Department of Bioengineering, Imperial College London, London, United Kingdom, ³School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom, ⁴Department of Physics, Imperial College London, London, United Kingdom

Patients undergoing MRI often experience anxiety and sometimes distress prior to and during scanning. We have developed a non-intrusive MR compatible Virtual Reality (VR) system, providing a tailored immersive experience that the user can interact with and control using gaze tracking. Dedicated VR content has been created and tested on adults and children. A key feature is congruency between the VR world and physical sensations during MRI, including VR features corresponding to table motion and scanner noise/vibration. Results suggest the approach has huge clinical potential, and it could represent a platform for conducting a new generation of “natural” fMRI experiments.

 

Huiyu Qiao¹, Shuo Chen¹, Dandan Yang¹, Hualu Han¹, Zihan Ning¹, and Xihai Zhao^1
1Tsinghua University School of Medicine, Beijing, China

The feasibility of T1, T2 and T2* in brain imaging and lesion quantification has been proved. However, studies about quantitative imaging seldom quantify T1, T2 and T2* together. This study proposed a three-dimensional (3D) simultaneous quantitative T1-T2-T2* mapping (SQUMA) for the whole brain. SQUMA sequence was composed of five dynamic scans using variable flip angles, variable T2 preparation duration and multi-echo acquisitions. SQUMA sequence showed excellent agreement with reference imaging in measuring T1, T2 and T2* values (R²=0.98, 0.84 and 0.90, respectively) and good to excellent repeatability in in-vivo studies. It is feasible to use SQUMA in clinical applications.

Petrice Mostardi Cogswell¹, Sandeep K Ganji², Daniel D Borup¹, Jeffrey L Gunter¹, John Huston III¹, and Clifford R Jack Jr^1
1Radiology, Mayo Clinic, Rochester, MN, United States, ²Philips Healthcare, Gainesville, FL, United States

CSF flow has been most commonly evaluated using a gated 2D phase contrast (PC) acquisition at the cerebral aqueduct or foramen magnum. However, real-time acquisitions that allow for evaluation of changes in flow with the cardiac and respiratory may provide additional insight into CSF dynamics disorders. In this study we apply a real-time EPI based PC acquisition for imaging of intracranial CSF flow at multiple intracranial locations. Quantitative analyses are validated by comparison with a standard phase contrast acquisition. Frequency spectra analysis demonstrates dominant variations in CSF flow with the cardiac and respiratory cycles.

Iris Asllani^1,2, Francesco Di Lorenzo³, Katerina Gialopsou³, Joseph G Woods^4,5, Marco Bozzali³, and Mara Cercignani^3
1Neuroscience, University of Sussex, Brighton, United Kingdom, ²Biomedical Engineering, Rochester Institute of Technologygy, Rochester, NY, United States, ³University of Sussex, Brighton, United Kingdom, ⁴Radiology, University of California San Diego, San Diego, CA, United States, ⁵University of Oxford, Oxford, United Kingdom

Short-term effects of transcranial direct current stimulation (tDCS) on CBF were measured using arterial spin labeling (ASL) MRI. Results showed that anodal surface stimulation of the motor region was followed by an increase in gray matter CBF in that region. Conversely, CBF in the stimulated region following a cathodal stimulation decreased. There was no effect of sham stimulation on the CBF of the stimulated area. These findings may help forge a new path toward a better understanding of the neuro-physiological effects of tDCS in humans.

Laura Eisenmenger¹, Grant Steven Roberts², Michael Loecher³, Leonardo Rivera-Rivera¹, Patrick Turski¹, Kevin M Johnson^1,2, and Oliver Wieben^1,2
1Radiology, University of Wisconsin - Madison, Madison, WI, United States, ²Medical Physics, University of Wisconsin - Madison, Madison, WI, United States, ³Radiology, Stanford University, Palo Alto, CA, United States

Endovascular intervention via a venous approach, or trans-venous embolization (TVE), has been increasing employed in the management of intracranial vascular lesions such as arteriovenous malformations (AVMs) and dural arteriovenous fistulas (DAVFs). Current pre-procedural planning is limited by overlapping, complex vascular anatomy and a lack of quantitative hemodynamic feature characterization. Using novel 4D flow MRI methods, high-resolution retrograde venous flow mapping with anatomical detail and dynamic flow fields can provide valuable information prior to TVE.  We will present our institutional experience using this method in representative intracranial vascular lesions.

Nikhil Deveshwar¹, Emil Ljungberg², Misung Han¹, and Peder E. Z. Larson^1
1Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States, ²Department of Neuroimaging, King’s College London, London, United Kingdom

This study presents a VFA approach for quantification of T₁ and relative proton density of the brain ultrashort-T₂* component. Measured T₁ values corresponding to the ultrashort-T₂* component were lower compared to T₁ values corresponding to long-T₂* components, and did not exhibit gray/white matter differences. Qualitatively, ultrashort-T₂* component fraction maps showed better gray/white matter contrast and clearer white matter structure delineation which we expect to be a more accurate representation of relative proton density. These results show that added VFA T₁ encoding in characterization of the brain ultrashort-T₂* component can more accurately differentiate white matter anatomy.

Robert Moskwa¹, Dipul Chawla², Corinne Henak², Azam Ahmed³, and Walter Block^1
1Medical Physics, University of Wisconsin-Madison, Madison, WI, United States, ²Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, United States, ³Neurological Surgery, University of Wisconsin-Madison, Madison, WI, United States

It is hypothesized that the proper surgical approach for intracerebral hemorrhage (ICH) victims should depend on clot rigidity. Neurosurgical experience indicates that brain clot rigidity varies across patients and varies spatially and temporally within each patient. We hypothesize that the wide range of clot rigidity in ICH will allow MR elastography (MRE) techniques to depict the heterogeneity over a wide dynamic range of rigidity. Longitudinal MRE, ultrasound elastography, and mechanical compression testing were performed on large ex-vivo swine blood clots. MR elastography shows promise for characterizing the rigidity of intracerebral hemorrhage as indicated by these ex-vivo tests.

Sultan Zaman Mahmud^1,2, Thomas S. Denney^1,2, Ronald J. Beyers², and Adil Bashir^1,2
1Department of Electrical and Computer Engineering, Auburn University, Auburn, AL, United States, ²Auburn University MRI Research Center, Auburn, AL, United States

Blood-brain barrier (BBB) plays a very important role in regulating water and nutrients delivery between vascular circulation and central nervous system (CNS). Any disruption in the blood brain barrier may cause the alteration of normal functional activity of the nervous system. The techniques currently available to measure BBB permeability are prone to certain limitations and potential side effects. In this study we demonstrated a non-invasive technique of evaluating BBB permeability using the magnetization transfer (MT) effect on endogenous water labeled by arterial spin labeling (ASL) technique as a perfusion tracer.

Till Huelnhagen^1,2,3, Mário João Fartaria^1,2,3, Ricardo Corredor-Jerez^1,2,3, Mazen Fouad A. Wali Mahdi¹, Gian Franco Piredda^1,2,3, Bénédicte Maréchal^1,2,3, Jonas Richiardi^1,2, and Tobias Kober^1,2,3
1Advanced Clinical Imaging Technology, Siemens Healthcare AG, Lausanne, Switzerland, Lausanne, Switzerland, ²Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland, ³LTS5, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland

A growing amount of imaging data is made publicly available. While this is desirable for science and its reproducibility, privacy concerns increase. As the shape of a face can be recovered based on MR images, an increased number of studies remove the face from the data to prevent biometric identification. This defacing can, however, pose a challenge to existing post-processing pipelines e.g. brain volume assessment. This work investigates the impact of regenerating facial structures in defaced images on morphometry in a large cohort using a deep neural network. The results show that refacing can prevent volumetric errors induced by defacing.