Yurii Shepelytskyi^1,2, Francis T Hane^2,3, Vira Grynko^1,2, Tao Li³, Ayman Hassan⁴, and Mitchell S Albert^2,3,5
1Chemistry and Materials Science Program, Lakehead University, Thunder Bay, ON, Canada, ²Thunder Bay Regional Health Research Institute, Thunder Bay, ON, Canada, ³Chemistry, Lakehead University, Thunder Bay, ON, Canada, ⁴Thunder Bay Regional Health Science Centre, Thunder Bay, ON, Canada, ⁵Northern Ontario School of Medicine, Thunder Bay, ON, Canada

Functional magnetic resonance imaging (fMRI) localizes active regions of the brain during brain stimuli. In this work, we demonstrate hyperpolarized (HP) ¹²⁹Xe fMRI in two classical fMRI experiments: a flashing visual stimulus and a fist-clenching motor stimulus. Using a chemical shift saturation recovery (CSSR) pulse sequence, our processed images localize brain activity to regions of the brain correlated to those identified using conventional Blood Oxygenation Level Dependent fMRI. The sensitivity of Xe fMRI was nearly two orders of magnitude greater than that of BOLD fMRI. In addition, ¹²⁹Xe fMRI allows presenting stimuli with significantly smaller repetition frequencies.

Ana-Maria Oros-Peusquens¹, Ricardo Loução¹, Monica Ferreira¹, and N. Jon Shah^1,2,3
1Research Centre Juelich, Juelich, Germany, ²Section JARA‑Brain, Jülich ‑Aachen Research Alliance (JARA), Aachen, Germany, ³Department of Neurology, RWTH Aachen University, Aachen, Germany

We present a method for high resolution, high precision measurements of water content in vivo, validated by comparison of the values obtained in the same brains at 3T and 7T. Applications relevant to brain structure and function are illustrated. The cortical distribution of water content simultaneously reflects its complement, the macromolecular content of tissue. Furthermore, a 3D “long TR” single-scan mapping method with 3deg excitation angle is proposed at 7T and delivers results consistent with the 2D method. Structural scans reflecting quantitative properties of tissue can thus be obtained in a short (7min or less) measurement time.

Stefano Mandija^1,2, Federico D'Agata^1,3, Hongyan Liu^1,2, Oscar van der Heide^1,2, Beyza Koktas², Cornelis A.T. van den Berg^1,2, Jeroen Hendrikse², Anja van der Kolk², and Alessandro Sbrizzi^1,2
1Computational Imaging Group for MR diagnostic and therapy, Center for Image Sciences, University Medical Center Utrecht, Utrecht, Netherlands, ²Department of Radiology, University Medical Center Utrecht, Utrecht, Netherlands, ³Department of Neurosciences, University of Turin, Turin, Italy

MR-STAT is a recently developed technique which aims at reconstructing multi-parametric quantitative maps (T1, T2, PD, etc.) from a short cartesian acquisition. Previous research efforts have focused on the feasibility of the MR-STAT framework from a technical point of view. In this work, we present the implementation of a five-minute long high-resolution whole-brain MR-STAT protocol in a clinical trial and show the first results obtained from nine subjects. Synthetically generated contrast images as well as quantitative parametric maps show the robustness and the practical feasibility of the 5 minute long comprehensive MR-STAT protocol.

Carolin M Pirkl^1,2, Laura Nuñez-Gonzalez³, Pedro A Gómez¹, Sebastian Endt^1,2, Rolf F Schulte², Guido Buonincontri^4,5, Marion Smits³, Bjoern H Menze¹, Marion I Menzel^2,6, and Juan A Hernandez-Tamames^3
1Informatics, Technical University of Munich, Munich, Germany, ²GE Healthcare, Munich, Germany, ³Radiology & Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands, ⁴Fondazione Imago7, Pisa, Italy, ⁵IRCCS Fondazione Stella Maris, Pisa, Italy, ⁶Physics, Technical University of Munich, Munich, Germany

In brain tumor diagnosis, fully quantitative, multiparametric MRI offers great opportunities as it allows for comprehensive tissue and hence tumor characterization which is essential for treatment planning and monitoring the treatment response. With its highly accelerated acquisition, advanced rapid MR mapping techniques facilitate multiparametric imaging in clinically acceptable scan times, providing quantitative, reproducible and accurate diagnostic information that is less affected by system and interpretation biases. In this work, we present initial clinical results and demonstrate the feasibility of a novel 3D multiparametric quantitative transient-state imaging (QTI) acquisition scheme in glioma patients.

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

In this study, we implemented a novel centric reordering scheme in a partial flow compensated 3D-iEPI to further reduce the flow effect and assessed its feasibility for a fast high-resolution SWI application. By properly dividing one interleave into two EPI shots sequentially acquired with opposite phase encoding gradient polarities and overlapping one line in the interleave center, we demonstrated that the partial flow compensated 3D-iEPI with such centric reordering scheme can significantly reduce the arterial contamination and obtain comparable contrast and image quality to 3D-GRE, whilst enjoying an approximate 2-fold reduction in acquisition time.

Eddy Solomon¹, Houchun H. Hu², Kai Tobias Block¹, Daniel K. Sodickson¹, and Hersh Chandarana^1
1Radiology, New York University School of Medicine, New York, NY, United States, ²Radiology, Nationwide Children's Hospital, Columbus, OH, United States

Inversion-recovery 3D T1 gradient echo sequences are commonly used in brain examinations for their excellent gray-/white-matter contrast. However, prominent motion artifacts can arise during lengthy Cartesian k-space sampling (typically 5-7 minutes) if the patient is not able to hold still, as is often the case for pediatric or elderly patients. Here, we present an alternative based on radial stack-of-stars imaging and show that comparable image contrast can be achieved, with lower sensitivity to head motion. Moreover, we demonstrate how the radial acquisition scheme can be utilized for additional retrospective motion correction to further improve robustness without increasing acquisition time.

Itamar Terem*¹, Leo Dang*², Allen Champagne³, Javid Abderezaei ⁴, Zainab Almadan ², Anna-Maria Lydon ⁵, Mehmet Kurt^4,6, Miriam Scadeng^2,7,8, and Samantha J Holdsworth^2,8
1Department of Electrical Engineering & Department of Structural Biology, Stanford University, Stanford, CA, United States, ²Department of Anatomy and Medical Imaging & Centre for Brain Research, University of Auckland, Auckland, New Zealand, ³Centre for Neuroscience Studies, Queen’s University, Kingston, ON, Canada, ⁴Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ, United States, ⁵Centre for Advanced MRI, University of Auckland, Auckland, New Zealand, ⁶Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States, ⁷Department of Radiology, University of California, San Diego, CA, United States, ⁸Mātai Medical Research Institute, Gisborne-Tairāwhiti, New Zealand

Amplified Magnetic Resonance Imaging (aMRI) has been introduced as a new brain motion detection and visualization method.  Originally employed to amplify pulsatile brain motion in 2D, aMRI has shown to be promising for differentiating abnormal from normal pulsatile brain motion in obstructive brain disorders. Here, we further improve aMRI with the introduction of a combined 3D aMRI acquisition and post-processing tool, with subsequent image processing with optical flow and strain mapping. The 3D aMRI tool is then tested on both multi-slice and volumetric data and its ability to capture 3D brain motion is analyzed. 

Sooyeon Ji¹, Se-Hong Oh², and Jongho Lee^1
1Electrical and Computer Engineering, Seoul National University, Seoul, Korea, Republic of, ²Biomedical Engineering, Hankuk University of Foreign Studies, Yongin, Korea, Republic of

A 2D quad-contrast sequence is developed to generate four different contrast images commonly used in the clinical patient scan (PDw, T₂w, T₁w, and FLAIR) and two quantitative maps (T₁- and T₂- maps) in 4:14 of scan time. The proposed sequence provides comparable tissue contrasts to that of conventional sequences. In particular, native FLAIR contrast is acquired, which does not display hyperintense brain surface that arises from partial volume error during parameter mapping. Psuedo-contrast images with different TE and TI are also synthesized utilizing the quantitative maps, analogous to MAGiC.

Ross W. Mair^1,2, Lindsay C. Hanford^1,3, Emilie Mussard^4,5,6, Tom Hilbert^4,5,6, Tobias Kober^4,5,6, and Randy L. Buckner^1,2,3
1Center for Brain Science, Harvard University, Cambridge, MA, United States, ²Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, ³Department of Psychology, Harvard University, Cambridge, MA, United States, ⁴Advanced Clinical Imaging Technology, Siemens Healthcare, Lausanne, Switzerland, ⁵Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland, ⁶LTS5, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland

Incoherent under-sampling and compressed-sensing reconstructions can reduce the scan time for a 1.0 mm MPRAGE down to as little as 60-90 seconds. Such time-savings permit the acquisition of multiple scans per session, allowing the variation of image metrics and brain morphometrics around their mean values to be quantified. We compared MPRAGE scans accelerated up to eight-fold with a fully-sampled MPRAGE; and using SNR, cortical thickness and gray matter volume, assessed the optimal regularization in the compressed-sensing reconstruction for each acceleration level to best match the values from the fully-sampled scan.

Difei Wang¹, Tony Stöcker^1,2, and Rüdiger Stirnberg^1
1German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany, ²Department of Physics and Astronomy, University of Bonn, Bonn, Germany

By comparison to a gold standard multiparametric mapping (MPM) protocol at 3T, this study shows that multi-echo 3D-EPI with highly segmented CAIPIRINHA sampling can yield whole-head T₁, PD*, MT_sat and R₂* maps of high quality at 1mm isotropic resolution in less than 3 minutes scan time. Even less than 1 minute of single-echo 3D-EPI is sufficient to yield accurate quantitative T₁, PD* and MT_sat maps. If necessary, SNR can be improved by including repeated EPI measurements. Optional motion- and distortion-correction across measurements may further improve results. Motion-robust MPM thus renders assessing quantitative parameter maps in clinical or population studies feasible.