Qing Dai^1,2, Le Zhang^1,3, Xinzhou Li^1,2, Pengkang Yu⁴, Tsu-Chin Tsao⁴, and Holden H. Wu^1,2
1Department of Radiological Sciences, University of California, Los Angeles, Los Angeles, CA, United States, ²Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, United States, ³Department of Radiology, Mayo Clinics, Rochester, MN, United States, ⁴Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, Los Angeles, CA, United States

Multi-baseline proton resonant frequency (PRF) shift MR thermometry has been proposed to address the potential mismatch between baseline images and images during thermal therapy in moving organs. Previous methods had to compromise the spatial coverage to increase temporal resolution for resolving motion. This work developed a dynamic 3D stack-of-radial multi-baseline PRF MR thermometry method to monitor high-intensity focused ultrasound heating in moving tissue. The proposed method achieved stable and accurate thermometry with volumetric coverage and high spatiotemporal resolution, validated in a tissue motion phantom with temperature probe measurements.

Ashmita De¹, Justin Grenier¹, and Alan Wilman^1
1Biomedical Engineering, University of Alberta, Edmonton, AB, Canada

Multiple-echo gradient echo sequences developed to simultaneously compute TOF-MRA, SWI and QSM in previous studies have either compromised TOF-MRA features or have not computed QSM. In this abstract, images were acquired in healthy volunteers at 3T with different parameter variations of the proposed 3D triple-echo gradient echo sequence with all TOF-MRA features. The effect of TOF-MRA features on phase and QSM were explored and corrected to obtain artifact-free QSM. The parameters of the sequence have been optimized to obtain TOF-MRA, SWI, QSM and R2* maps simultaneously.

Enlin Qian¹, Pavan Poojar¹, David H. Gultekin¹, J. Thomas Vaughan¹, Devashish Shrivastava¹, Zhezhen Jin², Brett E. Youngerman³, and Sairam Geethanath^1
1Columbia Magnetic Resonance Research Center, Columbia University, New York, NY, United States, ²Department of Biostatistics, Columbia University, New York, NY, United States, ³Columbia University Irving Medical Center, Columbia University, New York, NY, United States

We explore the feasibility of noninvasive temperature measurement around deep brain stimulation (DBS) leads using magnetic resonance fingerprinting (MRF) by leveraging 1) the dependency of T₁ on temperature; 2) MRF’s efficient T₁ and B₀ mapping. We conducted a T₁ and temperature calibration experiment and a lead calorimetry experiment on bovine muscle. The effects of B₀ inhomogeneity and temperature profiles of different regions of interest (ROI) were investigated. The calibration showed a strong correlation between temperature and T₁ (R²>0.98). We observed a maximum change of 10.2 ^oC near leads (~1mm away) during calorimetry experiments, validated by fluoroptic probes.

Eduard Y Chekmenev¹, Anna Samoilenko², Jonathan R. Birchall², Kirill V. Kovtunov³, Larisa M Kovtunova³, Valeriy I. Bukhtiyarov⁴, Igor V. Koptyug³, Chunqi Qian⁵, Boyd M Goodson⁶, and Nuwandi M. Ariyasingha^2
1Chemistry and Oncology, Wayne State University, Detroit, MI, United States, ²Chemistry, Wayne State University, Detroit, MI, United States, ³International Tomography Center RAS, Novosibirsk, Russian Federation, ⁴Boreskov Institute of Catalysis RAS, Novosibirsk, Russian Federation, ⁵Radiology, Michigan State University, Lansing, MI, United States, ⁶Southern Illinois University Carbondale, Carbondale, IL, United States

We demonstrate a disposable and handheld hyperpolarizer for clinical-scale production of hyperpolarized propane gas for application as an inhalable contrast agent for pulmonary MRI. The device consists of an aluminum commercial spray can, which contains a mixture of pressurized propylene and parahydrogen gases. This filled container can be easily transported and stored for weeks. The hyperpolarized propane production is initialized by valve actuation, which releases the propylene-parahydrogen mixture into a mini-catalytic reactor producing a stream of pure (without catalyst) hyperpolarized propane gas on demand. The feasibility of 3 T EPI, FIESTA, and GRE MRI in hyperpolarized phantoms is demonstrated.

Yongxian Qian¹, Liz Calderon¹, Xingye Chen¹, Anli Liu², Yvonne W. Lui¹, and Fernando E. Boada^1
1Radiology, New York University, New York, NY, United States, ²Neurology, New York University, New York, NY, United States

Neuronal firing generates fast action potentials along axon and slow postsynaptic currents at dendrites, which are difficult to detect and locate by scalp EEG and MEG placed above the skull. Here we propose local quantum sensing via endogenous proton (¹H) nuclear spins inside firing neurons and detect magnetic fields indued by both action potentials and postsynaptic currents. Computer simulations and human studies showed that the proposed technique has the potential to non-invasively detect and locate neuronal firings in the brain through the acquisitions of FID signal on a 3T MRI scanner with multi-channel array coil.

Pietro Irrera¹, Bruna Victorasso Jardim-Perassi¹, Epifanio Ruiz², Mikalai Budzevich², Justin YC Lau², and Robert J Gillies^1
1Cancer Physiology, Moffitt Cancer Center, Tampa, FL, United States, ²Small Animal Imaging Laboratory, Moffitt Cancer Center, Tampa, FL, United States

This work is based on a well-known MRI property, the transverse relaxation changes of bulk water due to the presence of a solute with water-exchangeable protons. Many molecules can exhibit this ability to change water T₂, such as glucose, urea, ammonium chloride, metals and paramagnetic complexes. Here we used the FDA-approved iodinated agent iopamidol (Isovue), widely used for CEST applications, as a T_2ex agent to quantify pH in vitro and in vivo, since its –NH groups exhibit pH-dependent exchange rates with water protons. Computed tomography provided iopamidol concentrations to complement the MR relaxometry measurements, allowing determination of pH in vivo.

Hung Phi Do¹, Dawn Berkeley¹, Brian Tymkiw¹, and Mo Kadbi^1
1Canon Medical Systems USA, Inc., Tustin, CA, United States

Two-dimensional Fast Spin Echo is a workhorse of clinical MRI. However, its minimum TE is in the order of milliseconds or tens of milliseconds, which limits its ability to image tissues with short T2*. This work aims to optimize the multi-echo ultra-short echo time (UTE) sequence to (i) visualize, (ii) generate an associated quantitative map of tissues with short T2*, and (ii) to produce CT-like images of bony structures, which often are not visible in clinical images routinely acquired using FSE sequence.

Erika P Raven¹, Jeffrey Bennett², Jelle Veraart¹, Claude Lepage³, Joey Charbonneau², Eliza Bliss-Moreau², and Jiangyang Zhang^1
1Radiology, NYU School of Medicine, New York, NY, United States, ²Psychology, UC Davis, Davis, CA, United States, ³Montreal Neurological Institute, McGill University, Montreal, QC, Canada

Mapping cortical myelination has been a long-standing goal for accurate parcellation and classification of cytoarchitectonic boundaries. We investigated a multivariate myelin mapping approach for the accurate parcellation of small cortical subregions of the insula by exploiting the co-localization of iron with dense bands of myelin in cortical gray matter. We assessed the performance of multivariate myelin mapping in the rhesus macaque, both in vivo and ex vivo, and compared its performance with T1w/T2w ratio imaging. We demonstrated that multivariate myelin mapping is a translatable myelin sensitive technique for the differentiation of insula subregions.

Jingwen Yao¹, Nikhil Deveshwar^1,2, and Peder E. Z. Larson^1
1Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States, ²Graduate Program in Bioengineering, UCSF/UC Berkeley, San Francisco, CA, United States

To improve the fitting performance of a UTE relaxometry model, we proposed an iterative decomposition method of multi-compartment relaxometry with least square estimations (IDMCR), based on Gauss-Newton estimations and incorporating spatial constraints. Monte Carlo simulation showed that IDMCR provided robust and unbiased estimation of ultra-short T₂* myelin fraction, which was further improved by adding spatial constraints. We examined the fitting algorithm in one healthy volunteer UTE relaxometry data and showed clear contrast of gray and white matter on the fitted myelin fraction map. The framework of IDMCR could also be easily adapted for other nonlinear parameter fitting problems.

Abubakr Eldirdiri¹, Jiachen Zhuo¹, Zixuan Lin², Hanzhang Lu^2,3,4, Rao Gullapalli¹, and Dengrong Jiang^2
1Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, Baltimore, MD, United States, ²The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States, ³Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, United States, ⁴F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, MD, United States

This work presents a multi vendor multi-site MRI study in which a TRUST sequence was harmonized across three MRI platforms from GE, Siemens, and Philips to measure the cerebral venous oxygenation Y_v. We carried out intra-scanner and inter-scanner analysis on the variability of the venous oxygenation measurements and demonstrated high measurements reproducibility across the three platforms.  Moreover, we examined the relationship between the fluctuations in end-tidal CO₂ and the Y_v measurements and showed that end-tidal CO2 can reduce the variability in Yv measurements in multi-site setting.

Linh N N Le¹, Gregory J Wheeler¹, Thomas Christen², Greg Zaharchuk³, and Audrey P Fan ^1,4
1Biomedical Engineering, University of California, Davis, Davis, CA, United States, ²Grenoble Institute of Neuroscience, Grenoble, France, ³Radiology, Stanford University, Palo Alto, CA, United States, ⁴Neurology, University of California, Davis, Davis, CA, United States

We compared two approaches of quantitative Blood-Oxygenation Level-Dependent (qBOLD) and vascular MR Fingerprinting (vMRF) to map brain oxygenation from Gradient-Echo Sampling of Free Induction Decay and Echo (GESFIDE) scans acquired during normoxic, hyperoxic, and hypoxic gas breathing conditions. In 12 healthy subjects, OEF calculated from qBOLD (qOEF) and OEF generated from vMRF (vOEF) were inversely correlated to pulse oxygenation (SaO₂) (p=0.032 and p=0.014, respectively), indicating that qBOLD and vMRF are reliable methods for brain oxygenation mapping.

Linh N N Le¹, Gregory J Wheeler², Alique M Momjian², Corinne A Donnay³, Nicholas P Blockley⁴, and Audrey P Fan^2,3
1Biomedical Engineering, University of California, Davis, San Diego, CA, United States, ²Biomedical Engineering, University of California, Davis, Davis, CA, United States, ³Neurology, University of California, Davis, Davis, CA, United States, ⁴School of Life Sciences, University Of Nottingham, Nottingham, United Kingdom

We quantified brain oxygen extraction fraction (OEF) using quantitative Blood-Oxygenation Level-Dependent (qBOLD) modeling of asymmetric spin echo (ASE) scans acquired at baseline and after pharmacological vasodilation with acetazolamide. In 9 healthy subjects, 60.51±42.00% CBF elevation and -8.45±9.71% OEF decrease in response to vasodilation was observed in multiple gray matter regions in the cortex. The correlation between cerebral blood flow (CBF) and OEF was inversely proportional (p=0.02), indicating complementary vascular responses to the acetazolamide stimulus.

Viola Rieke¹, Candace Floyd¹, Allison Payne¹, Henrik Odeen¹, Matt Zabriskie¹, Michelle Kline¹, Rock Hadley¹, Robb Merrill¹, and Lubdha Shah^1
1University of Utah, Salt Lake City, UT, United States

Many of the currently available low back pain (LBP) treatments are invasive with associated risks and complications. MR-guided Focused Ultrasound (MRgFUS) is a lower risk, completely non-invasive alternative modality. We developed a large animal chronic LBP model, induced by peripheral nerve injury, and evaluated the response with quantitative sensory testing (QST). Here we investigate the ability to decrease neuropathic LBP with FUS neuromodulation of the spinal dorsal root ganglion with MRgFUS. Our data suggest that the QST techniques are sensitive indicators of pain and that effects on pain reduction can be detected using this clinically relevant evaluation method.   
 

Babak Moghadas¹, C. Chad Quarles², and Vikram D. Kodibagkar^3
1Arizona State University, Tempe, AZ, United States, ²Barrow Neurological Institute, Phoenix, AZ, United States, ³School of Biological and Systems Engineering, Arizona State University, Tempe, AZ, United States

We developed and tested a novel iron based contrast agent for imaging hypoxia using magnetic resonance imaging (MRI). After synthesis, the cytotoxicity data and the magnetic properties were studied to measure the relaxivity of the contrast agent. The ability of the contrast agent in targeting hypoxic was demonstrated in vitro by comparing cell cultures under hypoxia by T1 and T2 mapping. The cytotoxicity assay showed no significant changes to the cells’ viability over the period of 8h exposure to the contrast agent. The retention in the hypoxic condition is an indication of its performance under the proposed mechanism.

Babak Moghadas¹, Jonathan Scirone¹, Matthew Scarpelli², Alberto Fuentes², C. Chad Quarles², and Vikram D. Kodibagkar^3
1Arizona State University, Tempe, AZ, United States, ²Barrow Neurological Institute, Phoenix, AZ, United States, ³School of Biological and Systems Engineering, Arizona State University, Tempe, AZ, United States

In this study we have used the hypoxia-targeting MRI contrast agent GdDO3NI, (a nitroimidazole-based T1 contrast agent) to image the development of hypoxia in two types of rodent brain tumor models. Our results indicate a range of signal enhancements from 0-17% over baseline in the C6 and 9L tumors using GdDO3NI with clearance from contralateral brain and muscle tissue. This study further demonstrates the utility of GdDO3NI in non-invasive imaging of tissue hypoxia with high resolution.

Zhitao Li¹, Yang Yang², and Li Feng^2
1Department of Radiology, Stanford University, Palo Alto, CA, United States, ²Biomedical Engineering and Imaging Institute and Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, United States

 

The repeatability of fast 3D T1 mapping using MP-GRASP (Magnetization-Prepared Golden-angle RAdial Sparse Parallel) MRI and its robustness to variation of imaging parameters including flip angle in phantom and brain were demonstrated. The experiments showed that MP-GRASP has a good robustness to B1 inhomogeneity, with intra-slice repeatability below 1% in the single tube phantom experiment. The longitudinal experiments also yielded good repeatability both in phantom (<2.5%) and in the brain (<2%) under various imaging conditions. The T1 values estimated are accurate relative to inversion recovery spin echo (IR-SE) gold standard (R2=0.997, Lin’s CCC=0.996).

Aman Khurana¹, Francesc Marti², Roberto Gedaly², and Fanny Chapelin^3
1Radiology, University of Kentucky, Lexington, KY, United States, ²Surgery, University of Kentucky, Lexington, KY, United States, ³Biomedical Engineering, University of Kentucky, Lexington, KY, United States

Due to their low cytoplasmic capacity and phagocytic activity, T cells have consistently been challenging to label for MR tracking applications. We developed a one-stop shop approach where the T cell sorting agent also labels the cells which can subsequently be imaged using non-invasive MRI. We demonstrate positive intracellular localization of the beads in Treg cells by means of histopathology analyses and MRI signal effects in phantoms containing different amounts of labeled cells.