Casey Anderson¹, Andrew Nencka², Tugan Muftuler³, Kathleen Schmainda², and Kevin Koch^2
1Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States, ²Radiology, Medical College of Wisconsin, Milwaukee, WI, United States, ³Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, United States

Quantitative susceptibility maps are routinely compromised by streaking artifacts. Here, we present a technique called volume-parcellated quantitative susceptibility mapping (VP-QSM), which performs independent susceptibility inversion on multiple reduced field-of-view parcels over the entire tissue field map.  These parcels are combined to form  a composite susceptibility map. In this algorithm, streaking artifacts are confined to individual parcels, improving the quality of the susceptibility map without a dependence on the underlying QSM inversion  algorithm.  In this study, VP-QSM is demonstrated on a 7T human volunteer, as well as on 30 subjects participating in sports concussion and brain cancer neuroimaging research protocols.  

Aditya Kumar Kasinadhuni¹, Munish Chauhan², Christopher Anderson¹, Michael Schär³, Aprinda Indahlastari², Paul Carney¹, Rosalind Sadleir², and Thomas Mareci^1
1University of Florida, Gainesville, FL, United States, ²Arizona State University, Tempe, AZ, United States, ³Johns Hopkins University, Baltimore, MD, United States

Magnetic resonance electrical impedance tomography (MREIT) relies on phase changes resulting from electric-current-induced magnetic fields in the direction of static magnetic field of an MRI scanner. Therefore MREIT can be employed to estimate conductivity/current density within the object being imaged. Characterizing current density in the brain is vital to improving our understanding of neuromodulation techniques like transcranial direct current stimulation (tDCS). In this study, to our knowledge, we performed the first MREIT brain scans of healthy human volunteers to localize the current-induced magnetic field generated by tDCS-like currents. These measurements allow estimation of current density in the human brain.

Jaewook Shin¹, Min-Oh Kim¹, Jun-Hyeong Kim¹, and Dong-Hyun Kim^1
1Electrical and Electronic engineering, Yonsei University, Seoul, Korea, Republic of

To reduce the noise amplification of the conductivity imaging, the direct calculation of the Laplacian operator was substituted by appropriate k-space weighted sampling scheme by the combination of four TSE data with alternating PE directions.

Jae-Woong Kim¹, Seong-Gi Kim^2,3, and Sung-Hong Park^1
1Korea Advanced Institute of Science and Technology, Daejeon, Korea, Republic of, ²Center for Neuroscience Imaging Research, Institute for Basic Science, Suwon, Korea, Republic of, ³Departments of Biomedical Engineering and Biological Sciences, Sungkyunkwan University, Suwon, Korea, Republic of

Phase images of pass-band bSSFP were investigated at multiple phase cycling (PC) angles at high field. Contrast between white matter and gray matter in phase images of pass-band bSSFP changed significantly with PC angle and was twice as high as that of phase images of gradient recalled echo at a specific PC angle. Phase images of pass-band bSSFP clearly demonstrated white matter and small structures presumed to be fiber bundles, which may not be easily visualized in the conventional methods. Phase imaging with pass-band bSSFP at multiple phase cycling angles may be a good anatomical imaging method at ultrahigh field.

Woojin Jung¹, Yoonho Nam², Hui Zhang³, and Jongho Lee^1
1Laboratory for Imaging Science and Technology, Department of Electrical and Computer Engineering, Seoul National University, Seoul, Korea, Republic of, ²Department of Radiology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea, Republic of, ³Department of Computer Science & Centre for Medical Image Computing, University College London, London, United Kingdom

A new in-vivo g-ratio mapping method that combined neurite orientation dispersion and density imaging (NODDI) and GRE myelin water imaging (GRE-MWI) is proposed. The method is substantially fast, taking 17 min for a 2 mm isotropic resolution whole brain g-ratio mapping. The resulting map reveals a reasonable range of g-ratio that has been reported in histology studies.

Yaotang Wu^1,2, Michael Marcotrigiano³, Hui Xue^1,2,4, Robert V Mulkern^1,2, and Jeffrey Neil^2,5
1Department of Radiology, Boston Children's Hospital, Boston, MA, United States, ²Harvard Medical School, Boston, MA, United States, ³Department of Research, Boston Children's Hospital, Boston, MA, United States, ⁴Sichuan University, Chengdu, China, People's Republic of, ⁵Department of Neurology, Boston Children's Hospital, Boston, MA, United States

A new method, ZUS, utilizes ZTE to detect all signals with T2* as short as a few hundred microseconds, including myelin proton signals, and UTE to selectively detect signals with longer T2* values, considered to be tissue water components. The difference of these two types of images is used to visualize signals from lipid 1H. In this study, the feasibility of ZUS was demonstrated on a cholesterol phantom (the major component of myelin) and on a live mouse. ZUS images highlighted lipid, particularly myelin in the corpus callosum, of mouse brain in vivo.

Junghun Cho¹, Dong Zhou², Pascal Spincemaille², and Yi Wang^1,2
1Biomedical Engineering, Cornell University, NEW YORK, NY, United States, ²Radiology, Weill Cornell Medical College, NEW YORK, NY, United States

In the study of quantitative susceptibility mapping, dipole approximation is widely used where the magnetic field of each voxel is approximated as dipole field. In general, higher order field such as quadrupole field also exists, especially for voxels with non-uniform subvoxel magnetization/susceptibility distributions. We modeled the magnetic field in MRI experiment up to quadrupole term and used multiple orientation measurement to acquire both the dipole (average susceptibility) and quadrupole (susceptibility distribution) contributions. The feasibility of the proposed method is demonstrated in an experimental gadolinium water phantom study.

Alkystis Phinikaridou¹, Prakash Saha², Marcelo Andia³, Alberto Smith², and René M Botnar^1
1Biomedical Engineering, King's College London, London, United Kingdom, ²Academic Surgery, King's College London, London, United Kingdom, ³Radiology, Pontificia Universidad Católica de Chile, Santiago, Chile

Deep vein thrombosis (DVT) affects 1 in 1000 people. Its sequelae include post-thrombotic syndrome (PTS), which affects up to 75% of patients within 5 years and is characterised by persistent pain, swelling and ulceration. Thrombolysis can reduce PTS by a third and is attempted in patients with an ilio-femoral DVT and symptom onset of <3weeks. Determining age and thrombus structure by history alone is, however, subjective and there are no established methods to quantify the abundance of matrix proteins, which determines the response to lysis. This treatment is therefore only effective in ~60% of patients, which may unnecessarily exposes to haemorrhagic side effects. We have developed a non-contrast enhanced magnetic resonance, multi-sequence thrombus imaging (MSTI) technique that can provide information about the structural composition of experimental thrombus [1-2]. Here, we aim in translating the MRI approach into man and determine whether it can help guide venous intervention.

caiyun shi¹, guoxi xie^1,2, xiaoyong zhang^1,3, min chen¹, shi su¹, hairong zheng¹, ying dong⁴, jim Ji⁴, and xin liu^1
1Shenzhen Institutes of Advanced Technology, shenzhen, China, People's Republic of, ²Beijing Center for Mathematics and Information Interdisciplinary Sciences, beijing, China, People's Republic of, ³Centers for Biomedical Engineering, College of Information Science and Technology, University of Science and Technology of China, hefei, China, People's Republic of, ⁴Department of Electrical and Computer Engineering, Texas A&M University, Texas, TX, United States

Susceptibility-based positive contrast MR imaging exhibits excellent efficacy for visualizing the MR compatible metallic devices, by taking advantage of their high magnetic susceptibility. In this work, a novel method is developed to accelerate the susceptibility-based positive contrast MR imaging. The method is based on a modified turbo spin echo (TSE) sequence and a kernel deconvolution algorithm with a regularized l1 minimization to achieve positive contrast imaging.

Ana-Maria Oros-Peusquens¹, Yupeng Liao¹, and N. Jon Shah^1
1INM-4, Research Centre Juelich, Juelich, Germany

About 80% of brain water is found inside the cells and a large fraction of it is interfacial water with properties substantially different from those of bulk water. Evidence for a large osmotically unresponsive compartment, available from literature, is substantiated by the finding that a very large fraction of brain water does not contribute to its electrical conductivity. This is determined by investigating the correlation between conductivity and water content in tumour patients in vivo. More than 80% of brain water is found to be unresponsive, with variations reflecting tissue and tumour type. This work describes a noninvasive method for the characterisation of a deeply microscopic parameter of the living tissue.