TRADITIONAL POSTER - ismrm

Poster Sessions
2944. Sensitivity of MRI Resonance Frequency to the Orientation of Brain Tissue Microstructure
Jongho Lee 1 , Karin Shmueli 1 , Masaki Fukunaga 1 , Peter van Gelderen 1 , Hellmut Merkle 1 , Afonso C. Silva 2 ,
Jeff H. Duyn 1
1 Advanced MRI/LFMI/NINDS, National Institutes of Health, Bethesda, MD, United States; 2 CMU/LFMI/NINDS, National Institutes
of Health, Bethesda, MD, United States
Here we demonstrate microstructural orientation affects the MRI resonance frequency. The experiment was designed to avoid macroscopic susceptibility
effect to identify true microstructural effect. We suggest an origin related to anisotropic susceptibility.
Relaxometry
Hall B Monday 14:00-16:00
2945. Wide-Range T1 Mapping Using Two Variable Flip Angle Acquisitions
Rahul Sarkar 1 , Alan R. Moody 1,2 , James Q. Zhan 2 , General Leung 1,2
1 Medical Biophysics, University of Toronto, Toronto, Ontario, Canada; 2 Medical Imaging, Sunnybrook Health Sciences Centre,
Toronto, Ontario, Canada
Variable flip angle (VFA) methods using two optimized flip angles have become popular for in-vivo T1 mapping within a limited range of a specific T1 of
interest. The range limitation in this approach is generally due to bias against long T1s in the signal-dynamic range product used for flip angle optimization.
This study presents a new strategy for flip angle pair selection that mitigates this bias to provide highly uniform accuracy and precision across the biological
T1 range. In using only two flip angle acquisitions, this method represents a rapid approach to wide-range VFA T1 mapping.
2946. Fast T 1 Mapping of Mouse Brain at 7 T with Time-Optimized Partial Inversion Recovery Utilizing a
Surface Coil
Naoharu Kobayashi 1 , Hironaka Igarashi 1 , Tsutomu Nakada 1
1 Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan
We present a new method for measuring a longitudinal relaxation time, T 1 , for a surface coil application utilizing adiabatic saturation pulses, referred to here
as time-optimized partial inversion recovery (TOPIR). The recovery delays before and after the inversion pulse were optimized to sample data points such
that the total sequence time was minimized under a specified dynamic range of the recovery curve. Accuracy of the method was validated by comparing the
values obtained utilizing conventional inversion recovery sequence. The method enabled a two dimensional T 1 mapping of a mouse brain using a 6 point
recovery curve in 20–36 s.
2947. The Effect of Heart Rate in Look-Locker Cardiac T 1 Mapping
Glenn S. Slavin 1 , Ting Song 1 , Jeffrey A. Stainsby 2
1 Applied Science Laboratory, GE Healthcare, Bethesda, MD, United States; 2 Applied Science Laboratory, GE Healthcare, Toronto,
ON, Canada
Because inversion times in cardiac Look-Locker acquisitions are a function of heart rate, T1 measurements can be incorrect. Pulse sequence modifications to
account for heart rate variability and its effect on the magnetization recovery curve can significantly improve T1 accuracy.
2948. Demonstrating the Influence of Magnetisation Transfer on Putative T 1 Relaxation Times: A Simulation
Study
Miriam Rabea Kubach 1 , Kaveh Vahedipour 2 , Ana Maria Oros-Peusquens 2 , Tony Stoecker 2 , N. Jon Shah 2,3
1 Institute of Neuroscience and Medicine , Forschungszentrum Juelich, Juelich, Germany; 2 Institute of Neuroscience and Medicine,
Forschungszentrum Juelich, Juelich, Germany; 3 Faculty of Medicine, Department of Neurology, , RWTH Aachen University, JARA,,
Aachen, Germany
T1 is an MRI parameter very sensitive to pathological changes. Proper T1-mapping is therefore vital for many MRI applications, but the variability of T1
values within different methods is larger than within a group of volunteers measured with the same method. The accuracy of the T1 determination is affected
by a number of rectifiable parameters but also influenced by MT in ways, which are strongly method-dependent and usually not quantified. We present
numerical simulations, based on an existing software package JEMRIS, which allow one to simulate MR sequences considering MT effects. We investigate
changes in the T1 relaxation of the observable water component due to the presence of and exchange with a bound proton pool. A simple pulse-acquire
sequence is used for simulations, which can be the elementary building block of more realistic MR imaging sequences.
2949. Fast T1/B1 Mapping Using Multiple Dual TR RF-Spoiled Steady-State Gradient-Echo Sequences
Tobias Voigt 1 , Stefanie Remmele 2 , Ulrich Katscher 2 , Olaf Doessel 1
1 Institute of Biomedical Engineering, University of Karlsruhe, Karlsruhe, Germany; 2 Philips Research Europe, Hamburg, Germany
Efficient and accurate baseline T1 and B1 quantification is a pre-requisite for standardized and clinical Dynamic Contrast-Enhanced MRI (DCE-MRI). This
study investigates a new approach called “Multiple TR B1/T1 Mapping” (MTM), capable of fast, simultaneous B1 and T1 mapping. In this work, MTM is
analysed with respect to its T1 mapping performance in comparison with an inversion recovery reference sequence and in due consideration of the limited
time allowed in a clinical set-up. In calibrated phantom measurements, MTM T1 mapping was found to be more accurate than IR-TSE, inter alia due to its
intrinsic B1 correction mechanism.