TRADITIONAL POSTER - ismrm

Poster Sessions
2983. Magnetic Resonance Imaging of the Neurotransmitter GABA in-Vivo
Kejia Cai 1 , Mohammad Haris 1 , Anup Singh 1 , Feliks Kogan 1 , Prianka Waghray 2 , Walter Witschey 1 , Hari Hariharan 1 ,
John A. Detre 3 , Ravinder Reddy 1
1 CMROI, Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States; 2 Department of Biology, Wake
Forest University, Winston-Salem, NC, United States; 3 Department of Neurology, and Center for Functional Neuroimaging,
University of Pennsylvania, Philadelphia, PA, United States
Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter of the brain and plays a critical role in multiple central nervous system diseases.
The objective of this study was to characterize the chemical exchange saturation transfer (CEST) effect of the -NH2 protons of GABA and to demonstrate
GABA imaging in the human brain at 7T. The Z-spectrum of GABA showed a pH sensitive asymmetry around ~2.75 ppm downfield to the water resonance.
CEST imaging of healthy human volunteers clearly showed the distribution of GABA CEST contrast in different regions of the brain with negligible contrast
from cerebrospinal fluid
2984. CEST and Sodium Imaging of Glycosaminoglycans In-Vivo on the 3T: Preliminary Results
Elena Vinogradov 1 , Alexander Ivanishev 1 , Aaron K. Grant 1 , Ron N. Alkalay 2 , David B. Hackney 1 , Robert E.
Lenkinski 1
1 Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States; 2 Department
of Orthopedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States
Quantitative assessment of Glycosaminoglycans (GAGs) in the clinical environment can assist with characterization of disorders associated with cartilage
degradation and loss. Sodium imaging and Chemical Exchange Saturation Transfer for GAG detection (gagCEST) are two of the several methods for GAG
assessment. Both methods rely on the endogenous effects. However, sodium imaging suffers from low sensitivity and requires specialized hardware.
GagCEST is a new method still in the validation phase. Both methods were implemented on the clinical 3T scanner for the purpose of the validation of the
techniques and the correlation between GAG state in-vivo as assessed using the two methods.
2985. Detection of Glycosaminoglycans Using Positive CEST Approach
Elena Vinogradov 1 , Robert E. Lenkinski 1
1 Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States
Chemical Exchange Saturation Contrast utilizes selective presaturation of a small pool of exchanging protons and is manifested in the decrease of the free
water signal. Recently, CEST method has been applied successfully to detect glycosaminoglycans (GAG) in cartilage. CEST contrast is negative, resulting in
decreased signal from areas with high agent (GAG) concentration. An alternative scheme, positive CEST (pCEST), results in the background suppression
and positive contrast when signal is increased due to the presence of the exchanging agent. Here we evaluate application of the pCEST to detect GAG in
solutions and ex-vivo samples.
2986. Improving Amide Proton Transfer Imaging with Dual Echo B 0 Mapping for Field Inhomogeneity
Correction at 3T
Wenbo Wei 1 , Guang Jia 1 , Steffen Sammet 1 , Peter Wassenaar 1 , Jinyuan Zhou 2 , Michael Knopp 1
1 Department of Radiology, The Ohio State University, Columbus, OH, United States; 2 Department of Radiology, Johns Hopkins
University, Baltimor, MD, United States
In this study, dual echo B 0 mapping was used in Amide Proton Transfer (APT) imaging for correcting B 0 inhomogeneity with fewer data points which will
lead to approximately one third of the current scan time and thus higher resolution. CEST spectrum, MTR asym curve and MTR asym (3.5ppm) encoded color
maps of the proposed APT method were compared to a conventional method. The proposed method offers a more accurate MTR asym curve shape and a
better determination of the water resonance frequency which allows a better MTR asym calculation.
2987. Optimization of RF Saturation to Minimize B 0 Inhomogeneity Effects in Pulsed Amide Proton
Transfer Imaging
Rachel Scheidegger 1,2 , Elena Vinogradov 1,3 , David C. Alsop 1,3
1 Radiology, Beth Israel Deaconess Medical Center, Boston, MA, United States; 2 Health Sciences and Technology, Harvard-MIT,
Cambridge, MA, United States; 3 Radiology, Harvard Medical School, Boston, MA, United States
Off-resonance errors due to magnetic field inhomogeneity are a major challenge for amide proton transfer imaging. Two-pool Bloch equation simulations
were used to optimize the timing for pulsed APT imaging with two different subtraction methods. Simulations indicate that the pulse width and interpulse
delay as well as the subtraction method used are key factors in optimizing APT for insensitivity to magnetic field inhomogeneity.
2988. Rapid CEST Detection Using EPI
Nevin McVicar 1 , Alex X. Li 2 , Robert Hudson 3 , Martyn Klassen 2 , Robert Bartha 1,2
1 Medical Biophysics, University of Western Ontario, London, ON, Canada; 2 Centre of Functional and Metabolic Imaging, Robarts
Research Institute, London, ON, Canada; 3 Chemistry, University of Western Ontario, London, ON, Canada
An Echo-planar imaging (EPI) pulse sequence was developed to detect CEST paramagnetic contrast. The EPI PARACEST sequence included a 2.5s CEST
saturation pulse, followed by a ~ 26ms echo-train. Signal to noise ratio (SNR), CEST effect, and CEST efficiency for EPI CEST sequence were compared to
fast spin-echo (FSE) CEST and fast low angle shot (FLASH) CEST in a phantom containing 10 mM Eu3+-DOTAM-Gly-Phe. EPI CEST, provided high
temporal resolution and SNR while fully maintaining CEST effect due to the short readout times. Decreasing readout bandwidth had no significant impact
on acquisition time or CEST contrast but increased image SNR.
2989. Optimized PARACEST Signal Detection by Echo-Planar Imaging
Adrienne Elizabeth Campbell 1,2 , Alex Li 1 , Craig Jones 3,4 , Robert Bartha 1
1 Centre for Functional and Metabolic Mapping, Robarts Research Institute, University of Western Ontario, London, Ontario, Canada;
2 Centre for Advanced Biomedical Imaging, University College London, London , Greater London, United Kingdom; 3 F.M. Kirby