TRADITIONAL POSTER - ismrm

Poster Sessions
1604. Effects of Turboprop Diffusion Tensor Imaging Acquisition Parameters on the Noise of Fractional
Anisotropy
Ashish A. Tamhane 1 , Konstantinos Arfanakis 1
1 Department of Biomedical Engineering, Illinois Institute of Technology, Chicago, IL, United States
The goal of this study was to investigate the effect of the number of blades, echo-train length (ETL), turbo-factor, and number of diffusion directions on the
noise of fractional anisotropy (FA) in Turboprop diffusion tensor imaging (DTI). It was shown that the range of FA standard deviation (std FA ) values for
different tensor orientations was lower when more diffusion directions were used. Additionally, std FA decreased for an increasing number of blades, lower
ETL, and lower turbo-factor. Hence, in Turboprop-DTI, optimal FA noise characteristics can be achieved by increasing the number of diffusion directions
and blades, and decreasing the ETL and turbo-factor.
1605. The Influence of Trapezoidal Gradient Shape on the B-Factor of Hyperecho Diffusion Weighted
Sequences
Stefanie Schwenk 1 , Matthias Weigel 1 , Valerij G. Kiselev 1 , Juergen Hennig 1
1 Department of Diagnostic Radiology, University Hospital Freiburg, Medical Physics, Freiburg, Germany
Diffusion weighted Hyperecho Imaging has maintained some interest during the last years since it has the potential to offer a probe for tissue microstructure.
The present work studies the influence of idealized rectangular gradient shapes on the quantitation of effective b-factors in diffusion weighted Hyperecho
preparation schemes for a variety of MR parameters.
1606. Improving High-Resolution Q-Ball Imaging with a Head Insert Gradient: Bootstrap and SNR Analysis
Julien Cohen-Adad 1,2 , Jennifer A. McNab 1,2 , Thomas Benner 1,2 , Maxime Descoteaux 3 , Azma Mareyam 1 ,
Van J. Wedeen 1,2 , Lawrence L. Wald 1,2
1 A. A. Martinos Center for Biomedical Imaging, Dept. of Radiology, MGH, Charlestown, MA, United States; 2 Harvard Medical
School, Boston, MA, United States; 3 MOIVRE Centre, Department of Computer Science, Université de Sherbrooke, Sherbrooke, QC,
Canada
Head-insert gradients are particularly suitable for diffusion-weighted (DW) imaging due to a higher maximum strength, higher switching rate and higher
duty cycle. In this paper we evaluate the performance of a head-insert combined with 32ch coil at 3T compared to conventional body gradients, for high
spatial and angular resolution diffusion-weighted imaging. Bootstrap-based metrics demonstrate higher reproducibility of the Q-Ball estimate and lower
uncertainty on the extracted maxima of the diffusion orientation distribution function.
1607. A Connectome-Based Comparison of Diffusion MR Acquisition Schemes
Xavier Gigandet 1 , Tobias Kober 2,3 , Patric Hagmann 1,4 , Leila Cammoun 1 , Reto Meuli 4 , Jean-Philippe
Thiran 1 , Gunnar Krueger 2
1 Signal Processing Laboratory (LTS5), Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; 2 Advanced Clinical
Imaging Technology, Siemens Schweiz AG-CIBM, Lausanne, Switzerland; 3 Laboratory for Functional and Metabolic Imaging, Ecole
Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; 4 Department of Radiology, Centre Hospitalier Universitaire Vaudois and
University of Lausanne, Lausanne, Switzerland
Diffusion MRI has evolved towards an important clinical and research tool. Though clinical routine is mainly using diffusion tensor imaging (DTI)
approaches, q-ball imaging (QBI) and diffusion spectrum imaging (DSI) have become often used techniques in research oriented investigations. In this work,
we aim at assessing the performance of various diffusion acquisition schemes by comparing the respective whole brain connection matrices. The results from
the analysis indicate that (a) all diffusion scans produce a biologically meaningful mapping of the human connectome, and (b) more non-dominant fiber
populations, e.g. neighboring association fibers in the 60-90 mm range, are better revealed with more complex diffusion schemes.
1608. Effects of Diffusion Time on Diffusion Tensor Derived Parameters Measured on the Rat Brain at
Ultrahigh Magnetic Field
Yohan van de Looij 1,2 , Nicolas Kunz 1,2 , Petra S. Hüppi 1 , Rolf Gruetter 2,3 , Stéphane V. Sizonenko 1
1 Division of Child Growth & Development, Department of Pediatrics, University of Geneva, Geneva, Switzerland; 2 Laboratory for
Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; 3 Department of Radiology,
University of Geneva and Lausanne, Geneva and Lausanne, Switzerland
A large number of small bore systems propose implemented sequences making easy the use of DTI but the choice of sequence parameters can have a huge
impact on the derived tensor quantifications. The aim of this work was to study the influence of diffusion time (td) and brain microstructures on diffusion
derived parameters in the rat brain at 9.4T. 3 repeated DTEPI images (4 shots) were performed with td = 10, 25 and 39 ms respectively. This study shows in
white and gray matter a dependence of diffusion derived parameters on td from 10 ms to 25 ms.
1609. Using Statistical Resampling and Geometric Least Squares to Improve DTI Measures Efficiently
Paul Andrew Taylor 1 , Bharat B. Biswal 1
1 Radiology, UMDNJ, Newark, NJ, United States
An efficient method for improving DTI analysis is presented; geometric fitting and statistical resampling are used to calculate diffusion ellipsoids and
associated quantities of interest with confidence intervals, and to greatly reduce the necessary number of gradient measures and therefore the scan time.