Diego A Caban-Rivera¹, Daniel R Smith¹, Matthew DJ McGarry², L. Tyler Williams¹, Grace McIlvain¹, Elijah EW Van Houten³, Keith D Paulsen², Phil V Bayly⁴, and Curtis L Johnson^1
1University of Delaware, Newark, DE, United States, ²Dartmouth College, Hanover, NH, United States, ³Université de Sherbrooke, Sherbrooke, QC, Canada, ⁴Washington University in St. Louis, St. Louis, MO, United States

This study combined multi-excitation MR Elastography (ME-MRE) with a transversely isotropic inversion nonlinear inversion algorithm and diffusion tensor imaging (DTI) fiber directions to investigate anisotropic white matter tract integrity in aging. Participants were 5 older adults and 17 young adults. MRE outcomes include substrate shear modulus, μ, shear anisotropy, φ, tensile anisotropy, ζ, and DTI measures were also examined. Shear and tensile anisotropies were significantly different in the Corona Radiata and Superior Longitudinal Fasciculus. Diffusion measures were significantly different between groups in most tracts. These results suggest sensitivity of anisotropic properties to biological changes along white matter tracts in aging.

Kyra E. Twohy¹, Peyton L. Delgorio², Alexa M. Diano², Mary K. Kramer², Alexis M. Merritt², Grace McIlvain², Lucy V. Hiscox³, and Curtis L. Johnson^2
1Mechanical Engineering, University of Delaware, Newark, DE, United States, ²Biomedical Engineering, University of Delaware, Newark, DE, United States, ³Psychology, University of Bath, Bath, United Kingdom

This study tested the utility of high-resolution magnetic resonance elastography (MRE) to analyze frontal cortex degradation due to advancing age. Brain tissue stiffness significantly varied in frontal cortex regions and frontal cortex stiffness also significantly decreased with age. A significant interaction between age and region was found, indicating regions changed differently with age. The stiffness of all frontal cortex regions degraded more per year than reported whole frontal lobe stiffness loss, indicating greater loss in the cortex with age. This approach brings potentially increased sensitivity and specificity to the structure-function relationship found in the frontal cortex with age. 

Jiahui Li¹, Xin Lu¹, Zheng Zhu¹, Kyle J. Kalutkiewicz¹, Taofic Mounajjed², Yi Sui¹, Kevin J. Glaser¹, Safa Hoodeshenas¹, Sudhakar K. Venkatesh¹, Armando Manduca¹, Vijay H. Shah³, Richard L. Ehman¹, Alina M Allen³, and Meng Yin^1
1Radiology, Mayo Clinic, Rochester, MN, United States, ²Anatomic Pathology, Mayo Clinic, Rochester, MN, United States, ³Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, United States

Multiparametric MRI/MRE and liver biopsy were performed in 104 patients at risk for NASH. We correlated measurements of proton density fat fraction (PDFF), 3D vector MRE-assessed liver stiffness (LS), and T1 relaxation time across histological features of NASH. We found that PDFF showed superior diagnostic performance in identifying patients with NASH (AUC: 0.84 [0.76, 0.92]), while LS showed superior diagnostic performance in stratifying NASH patients at high risk (0.85 [0.75, 0.94]). The results showed that T1 measurement, either alone or in combination with other biomarkers, did not perform as well as PDFF and LS in diagnosing NASH or stratifying high-risk NASH.

Daniel R. Smith¹, Diego A. Caban-Rivera¹, L. Tyler Williams¹, Matthew McGarry², Elijah Van Houten³, Phil V. Bayly⁴, Keith Paulsen², and Curtis L. Johnson^1
1Biomedical Engineering, University of Delaware, Newark, DE, United States, ²Thayer School of Engineering, Dartmouth College, Hanover, NH, United States, ³Universite de Sherbrooke, Sherbrooke, QC, Canada, ⁴Mechanical Engineering and Materials Science, Washington University in St. Lous, St. Louis, MO, United States

In this study, we utilized MR elastography (MRE) and transversely isotropic inversion to estimate anisotropic material parameters of muscle during contraction states, including passive muscle lengthening and isometric contraction. We collected MRE and DTI data on six subjects and took averages of the parameters within the medial and lateral heads of the gastrocnemius muscle and compared the results during the contraction states. We found significant differences between the estimates during the various states of contraction. Here we demonstrate that MRE and TI-NLI can generate anisotropic parameter estimates for muscle tissue while capturing changes to functional aspects of the tissue.

Giacomo Annio^1,2, Robin Bugge³, Siri Fløgstad Svensson³, Omar Darwish⁴, Giorgio Seano⁵, Donata Biernat⁶, Karoline Skogen⁶, Jon Ramm-Pettersen ⁷, David Nordsletten⁸, Einar Vik-Mo ⁷, Katharina Schregel⁹, Kyrre Eeg Emblem³, and Ralph Sinkus^1
1LVTS - U1148, University Paris, Paris, France, ²School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom, ³Department of Diagnostic Physics, Division of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway, ⁴Department of Biomedical Engineering, King's College London, London, United Kingdom, ⁵U1021 INSERM, Institut Curie, Paris, France, ⁶Department of Radiology Ullevål, Division of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway, ⁷Department of Neurosurgery, Division of Clinical Neuroscience, Oslo University Hospital, Oslo, Norway, ⁸Department of Biomedical Engineering and Cardiac Surgery, University of Michigan, Ann Arbor, MI, United States, ⁹Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Germany

Distinctive traits of malignant tumours are abnormal angiogenesis and  high pressure. Conventional magnetic resonance imaging (MRI) plays a critical role in radiological evaluation of patients and tumour grading, but challenges remain. Pressure and vasculature have a strong impact on the tissue rheology and therefore they can be quantified by Magnetic Resonance Elastography (MRE). We show that MRE allows to quantify non-invasively tumour grade using pressure and tumour vasculature through wave scattering. We believe that MRE could play a central role in tumour grading and diagnosis as well as in therapy planning and dosage, especially in multidrug treatments scenarios.

Maria Rosaria Ruggiero¹, Hamza Aït Itto², Simona Baroni¹, Jean Boutonnat³, François Berger², Lionel Marc Broche⁴, Silvio Aime¹, Simonetta Geninatti¹, and Hana Lahrech^2
1University of Torino, Torino, Italy, ²BrainTech Lab INSERM U1205, Grenoble, France, ³CHU Grenoble, Grenoble, France, ⁴University of Aberdeen, Aberdeen, United Kingdom

R₁-dispersion profiles of in vivo glioma mouse models acquired by Fast-Field-Cycling NMR (FFC-NMR) were found to discriminate invasion from proliferation at fields below 2mT. These differences were correlated to the transcytolemmal water-exchange, demonstrating the water cell influx/outflux role in relaxation mechanisms. Hypoxia and H₂O₂, two major pathophysiological processes of invasion, were demonstrated to modulate relaxation. Immunohistochemistry of aquaporins AQP1 and AQP4 showed that the water-channel proteins were overexpressed in invasion but not in proliferation, suggesting that relaxations at low-field are modulated by water-exchange under the AQP1 and AQP4 control.  The method can be extended to FFC imaging.

Omid Yaghmazadeh¹, Mihaly Voroslakos¹, Mark Mattingly², Zakia Ben Youss Gironda³, Youssef Zaim Wadghiri³, Seena Dehkharghani^3,4, and Leeor Alon^3,4
1Neuroscience, New York University School of Medicine, New York, NY, United States, ²Bruker cooperation, Billerica, MA, United States, ³Department of Radiology, New York University School of Medicine, New York, NY, United States, ⁴Center for Advanced Imaging Innovation and Research (CAI2R), New York University School of Medicine, New York, NY, United States

We introduce an in-vivo multinuclear MR thermometry technique which utilizes the unique frequency shift between water and sodium resonant frequencies. Reconstruction of the absolute temperature is validated using chemical shift imaging conducted on a rodent model implanted with a thin fiber optic probe for monitoring.

Dengrong Jiang¹, Peiying Liu^1,2, Zixuan Lin¹, Abhay Moghekar³, Jay J. Pillai^1,4, and Hanzhang Lu^1,5,6
1Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States, ²Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, Baltimore, MD, United States, ³Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, United States, ⁴Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD, United States, ⁵Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, United States, ⁶F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, MD, United States

The medial temporal lobe (MTL), including the hippocampus, is a key area implicated in many brain diseases, such as Alzheimer’s disease. Since neural activity is tightly coupled to the brain’s oxygen consumption, oxygen-extraction-fraction (OEF) in the MTL (MTL-OEF) may serve as a functional biomarker for this critical region. In this work, we developed a novel non-invasive MRI technique, AS-aTRUPC, to specifically measure the MTL-OEF in the human brain. We found that in healthy volunteers, the MTL-OEF is lower than the cortical OEF. The sensitivity of our technique in detecting changes in MTL-OEF was demonstrated in caffeine challenge experiments.

Enrica Wilken¹, Ina Fredrich¹, Asli Havlas¹, Felix Freppon¹, Max Masthoff¹, and Cornelius Faber^1
1TRIC, Clinic of Radiology, University Hospital Muenster, Muenster, Germany

We validate that time-lapse MRI is able to resolve and follow single immune cells patrolling the brain vasculature. For that reason, we simulate motion-dependent contrast based on artificial k-space, imitate migrating cells with a rotating phantom system, and track iron-labeled monocytes in vivo with repeated T2* weighted imaging. Furthermore, we show that time-lapse MRI allows to differentiate between different motion patterns non-invasively and with whole-brain coverage, and to study altered motion behavior upon inflammatory stimulus and the onset of immune responses distant from the site of inflammation.

Emily Pedrick¹, Darryl B Sneag¹, Philip G Colucci¹, Mylinh Duong¹, Alyssa Vanderbeek¹, and Ek T Tan^1
1Hospital for Special Surgery, New York, NY, United States

This study investigated the effectiveness of a low-dose (25% of a single treatment dose for anemia) ferumoxytol-infusion for vascular suppression in T2-weighted MR neurography of the brachial plexus. 3D STIR-FSE and 2D Dixon-FSE sequences of the brachial plexus were acquired in 12 healthy volunteers pre- and post-ferumoxytol. Quantitative and subjective assessments by two readers demonstrated superior vascular suppression and nerve visualization post-ferumoxytol without negatively affecting soft tissue contrast or fat suppression.

Emma Bluemke¹, Eleanor Stride¹, and Daniel Bulte^1
1Institute of Biomedical Engineering, University of Oxford, Oxford, United Kingdom

The paramagnetic relaxivity effect of oxygen on longitudinal relaxation rate (R1) has been explored as a means of inferring partial pressure of oxygen in the tissue or bodily fluids, and examining tissue R1 response to hyperoxic gas breathing is used in research techniques such as oxygen-enhanced MRI. We present a 3-compartment model for estimating the hyperoxia-induced changes in R1 of tissues depending on B0, SO₂, blood volume, hematocrit, oxygen extraction fraction, and changes in blood and tissue PO₂. It is easy for researchers to tailor this model to their tissue of interest by substituting preferred tissue oxygen diffusion/consumption models.

Niklas Wallstein¹, Andreas Pöppl², Andrea Capucciati³, André Pampel ¹, Carsten Jäger¹, Fabio A. Zucca⁴, Enrico Monzani³, Luigi Casella³, Luigi Zecca⁴, and Harald E. Möller^1,2
1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany, ²Leipzig University, Faculty of Physics and Earth Sciences, Felix Bloch Institute for Solid State Physics, Leipzig, Germany, ³Department of Chemistry, University of Pavia, Pavia, Italy, ⁴Institute of Biomedical Technologies, National Research Council of Italy, Segrate, Italy

Neuromelanin-sensitive MRI receives interest as potential biomarker in neurodegenerative diseases, such as Parkinson’s and Alzheimer’s disease. It is known that human neuromelanin pigments bind large quantities of toxic metal ions, especially iron but also other transition metals including copper. These melanin-iron complexes are a potential source of paramagnetic relaxation enhancement of water proton. In relaxometry investigations, we found deviations from a simple linear concentration-dependent T1 shortening in synthetic neuromelanins containing different amounts of iron and copper. Knowledge of the occupation of distinct metal binding sites seems crucial for contrast optimization or attempts to quantify metal content by MRI.