Kyeongseon Min¹, Jongho Lee¹, and Jang-Yeon Park^2,3
1Department of Electrical and Computer Engineering, Seoul National University, Seoul, Korea, Republic of, ²Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Korea, Republic of, ³Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon, Korea, Republic of

In this study, the effect of the electric potential of lipid vesicle surfaces on MR relaxation times and magnetization transfer was investigated. Negatively charged multilamellar vesicles were formed, and their surface potential was adjusted by changing the sodium ion concentration. While the zeta potential changed from -57.0 mV to –21.6 mV, T₂ increased from 48.2 ms to 67.4 ms, PSR decreased from 5.5% to 5.0%, k_mf decreased from 82.7 Hz to 40.6 Hz, and T_2b increased from 177.8 μs to 189.1 μs. These observations are expected to be utilized to image action potential generated in white matter.

Seong-min Kim¹, Kyeongseon Min², and Jang-Yeon Park^1,3
1Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Republic of Korea, Suwon, Korea, Republic of, ²Laboratory for Imaging Science and Technology, Department of Electrical and Computer Engineering, Seoul National University, Seoul, Republic of Korea, Seoul, Korea, Republic of, ³Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon, South Korea, Suwon, Korea, Republic of

To find novel contrast mechanisms of neuronal activity, our group previously demonstrated using in vitro cells that changes in membrane potential induces changes in MR parameters. There are two plausible factors that may contribute when the membrane potential changes: the dynamics of hydration water, and cell swelling. In this study, we investigated if cell swelling can contribute to changes in T₂ under a constant membrane potential using non-excitable cells. As a result, we found that cell swelling induces measurable changes. As the cell size increased, the short T₂ component caused by the intracellular water increased and vice versa.

Zheng Zhong¹, Xiaozhi Cao¹, Congyu Liao¹, Zhitao Li¹, Ali Syed¹, Kawin Setsompop¹, and Shreyas S. Vasanawala^1
1Radiology, Stanford University, Stanford, CA, United States

T2-weighted imaging is conventionally obtained using multi-slice 2D or 3D fast spin-echo (FSE) sequences. However, FSE suffers from severe specific absorption rate (SAR) issue and motion artifact particularly in the abdomen. A potential approach to address these challenges is using T2-prepared 3D SPGR sequence with a non-Cartesian trajectory such as cones. In this study, we proposed a T2-prepared 3D-cones sequence to achieve T2-weighted abdominal imaging with free breathing. The feasibility of the technique was tested on both healthy subjects and patients.

Ana-Maria Oros-Peusquens¹, Luis Hau¹, and N. Jon Shah^1,2,3,4
1Institute of Neuroscience and Medicine INM-4, Research Centre Juelich, Juelich, Germany, ²Department of Neurology, RWTH Aachen University, Aachen, Germany, ³Faculty of Medicine, JARA, RWTH Aachen University, Aachen, Germany, ⁴Institute of Neuroscience and Medicine 11, INM-11, JARA, Research Centre Juelich, Juelich, Germany

Understanding MR contrast/relaxation in vivo based on myelin and iron content is an on-going endeavour. We study the age dependence and correlation of QSM, R2, R2’ and R2* in vivo with whole brain coverage, investigating whether the interplay between demyelination and iron increases explains changes in these four qMRI parameters. The observations suggest that age-related influences proceed mostly by the intra-cellular iron effect on QSM and demyelination effect on R2.

Yikun Wang¹, Ruokun Li¹, Jiahao Zhou¹, Chengyan Wang², and Fuhua Yan^1
1Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China, ²Human Phenome Institute, Fudan University, Shanghai, China

Hepatic venous pressure gradient (HVPG) measurement is the standard technique of assessing portal pressure. Portal hypertension is mainly caused by increased intrahepatic resistance to portal blood flow related to structural changes, including fibrosis and vascular distortion. Here, we used dynamic contrast-enhancement (DCE) MRI to quantify segmented liver contours and vascular morphology in evaluating portal pressure. Our study showed the MRI measurements correlated well with HVPG measurement. A non-invasive prediction model combining liver vascular morphology and liver surface nodularity (LSN) can potentially be used to assess clinically significant portal hypertension (CSPH).

Elizabeth G. Keeling^1,2, Maurizio Bergamino¹, Sudarshan Ragunathan¹, C. Chad Quarles¹, and Ashley M. Stokes^1
1Barrow Neurological Institute, Phoenix, AZ, United States, ²Arizona State University, Tempe, AZ, United States

BOLD-fMRI is widely used to study brain activity but suffers from signal dropout near air-tissue interfaces and lack of sensitivity to microvasculature. A combined spin- and gradient-echo (SAGE) acquisition, previously implemented for perfusion MRI, may be able to reduce signal dropout and provide sensitivity to microvasculature for fMRI applications. SAGE-fMRI presents its own challenges, namely lack of full brain coverage and poor temporal and spatial resolution. These challenges can be overcome by combining in-plane and through-plane acceleration factors. This study aims to optimize the SAGE-fMRI protocol, balancing acceleration of acquisition with image quality.

Yang Ji¹, Dongshuang Lu¹, and Phillip Zhe Sun^1,2
1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States, ²Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA, United States

Given the association between MT and longitudinal relaxation rate (1/T₁), we hypothesized that T_1app, under RF saturation, can be estimated from T₁ to improve CBF quantification. Using Wistar rats, we showed that the T_1app over T₁ ratiometric map (i.e., T_1app/T₁) is homogeneous despite large regional variation in T₁ and T_1app maps. Therefore, we postulated that T_1app map could be estimated from the routine T₁ map instead of T_1app, which is cumbersome and not straightforward. A fast T_1app estimation provides satisfactory Cerebral blood flow (CBF) measurement across the brain, not affected by the concomitant MT effect.  

Ken-Pin Hwang¹, Kim O. Learned², Naoyuki Takei³, R. Marc Lebel⁴, Peter Johansson⁵, David Shin⁶, Xinzeng Wang⁷, Catharina Petersen⁵, Marcel Warntjes⁵, Suchandrima Banerjee⁶, and Linda Chi^2
1Department of Imaging Physics, The University of Texas M.D. Anderson Cancer Center, Houston, TX, United States, ²Department of Neuroradiology, The University of Texas M.D. Anderson Cancer Center, Houston, TX, United States, ³GE Healthcare, Hino, Japan, ⁴Global MR Applications and Workflow, GE Healthcare, Calgary, AB, Canada, ⁵SyntheticMR, AB, Linkoping, Sweden, ⁶GE Healthcare, Menlo Park, CA, United States, ⁷GE Healthcare, Houston, TX, United States

Brain data with high grade glioma were acquired with a 3D multiparameter mapping sequence and reconstructed with a novel deep learning based method (DL Recon). Synthetic images created from maps fitted to the reconstructed images were rated by experienced radiologists for image quality and diagnostic utility. Images from the DL Recon workflow consistently rated equal to or better than those created from conventional reconstruction. We find that the SNR and resolution benefits of 3D DL Recon extend to improve the resulting relaxation maps and subsequent synthetic images.

Ross Shaw¹, Penny Gowland², and Richard Bowtell^3
1Physics, University of Nottingham, Nottingham, United Kingdom, ²University of Nottingham, Nottingham, United Kingdom, ³SPMIC, University of Nottingham, Nottingham, United Kingdom

Simultaneous measurements of R₂ and R₂’ using the Gradient Echo Sampling of a Spin Echo (GESSE) sequence were made at multiple spin echo times in four volunteers. Secondary measurements of R₂ and R₂* were made using classical Spin Echo and Gradient Echo approaches. The variation in measured relaxation rates are explored and show a general overestimation of transverse relaxation in white and grey matter when measured with GESSE suggesting a lack of complexity in the model used to describe the GESSE signal.

Fábio Seiji Otsuka¹, Khallil Chaim², Maria Otaduy², and Carlos Salmon^1
1InBrain, Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil, ²Departamento de Radiologia e Oncologia, Faculdade de Medicina, Universidade de Sao Paulo, São Paulo, Brazil

On this study, the impact of temperature and postmortem interval (PMI) on QSM were evaluated for a total of 21 subjects. Temperature and PMI were correlated with values from CSF, white matter (WM) and gray matter (GM). Only the GM presented a significant correlation with both temperature and PMI.

Alexander Robert Bricco¹, Illiya Miralavy¹, Shaowei Bo², Or Perlman³, Christian Farrar³, Mike McMahon², Wolfgang Banzhaf¹, and Assaf Gilad^1
1Michigan State University, East Lansing, MI, United States, ²Johns Hopkins University, Baltimore, MD, United States, ³Harvard Medical School, Boston, MA, United States

Reporter genes for MRI allow for the non-invasive observation and evaluation of gene and cell therapies which are being rapidly developed. Traditional methods of gene optimization failed to improve reporter gene quality. We developed and employed a novel machine learning program called the Protein Optimizing Evolving Tool (POET). Using POET we have discovered peptides which provide more contrast than prior efforts and also display properties that challenge prior knowledge on the functions of these genes.

Humberto Monsivais¹, Xin Shen², Antonia Susnjar², Ali Caglar Özen³, Serhat Ilbey ³, Mark Chiew ⁴, Aparna Karnik⁵, Uzay Emir^1,2, and Ulrike Dydak^1,6
1School of Health Sciences, Purdue University, West Lafayette, IN, United States, ²Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States, ³Department of Radiology, Medical Physics, University of Freiburg, Freiburg, Germany, ⁴Wellcome Centre for Integrative Neuroimaging, University of Oxford, England, United Kingdom, ⁵Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, United States, ⁶Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, IN, United States

This phantom study aimed to compare a conventional multi-gradient recalled echo (mGRE) sequence and an ultra-short echo (UTE) with a novel 3D rosette k-space trajectory for iron (Fe) detection and quantification. Conventional mGRE imaging may underestimate massive Fe load due to the long echo times (TEs). Advanced UTE techniques with TEs 10-200 times shorter than conventional mGRE sequences can capture fast signal decay caused by high Fe content. Our preliminary results show that both sequences yield a strong linear relationship between R2* values and Fe concentrations, with the 3D-UTE results aligning more with expected R2* values for high Fe concentrations.