ELECTRONIC POSTER - ismrm

14:00 3961. MRI Motion Compensation by Ultrasound Navigators
Benjamin Matthew Schwartz 1 , Nathan McDannold 2
1 Biophysics, Harvard University, Boston, MA, United States; 2 Radiology, Harvard Medical School, Boston,
MA, United States
A well-known technique to reduce motion artifacts uses MR navigator echoes to track the position of the object being imaged, and
compensates for the motion using this position information. We demonstrate an analogous technique, tracking motion using A-line
images from a single ultrasound transducer. The ultrasound data can be analyzed in real time for prospective motion correction, or
processed offline for retrospective correction. Ultrasound navigation allows the use of unmodified pulse sequences, with attendant
advantages in acquisition speed, steady-state polarization, and reduced engineering requirements. Future development includes
multidimensional tracking and supplying position data to non-MR equipment.
14:30 3962. Characterising Gradient Non-Linearities of a Split Gradient Coil in a Hybrid MRI-
Linear Accelerator
Sjoerd Crijns 1 , Johan Overweg 2 , Bas Raaymakers 1 , Jan Lagendijk 1
1 Department of Radiotherapy, UMC Utrecht, Utrecht, Netherlands; 2 Medical Imaging Systems, Philips
Research Europe, Hamburg, Germany
The performance of a split gradient coil for MRI guided radiotherapy is evaluated in terms of geometrical accuracy.
15:00 3963. Precise Co-Registration of SPECT and MRI for Small Animal Imaging Using a
Common Animal Bed with External References:Visualization of Macrophage Distribution
Within Inflammatory Lymph Nodes
Masayuki Yamaguchi 1 , Daisuke Suzuki 1,2 , Ryosuke Shimizu 1,2 , Ryutaro Nakagami 1,3 ,
Keisuke Tsuda 1 , Izumi Ogihara Umeda 1 , Yasuo Okuyama 2 , Kohki Yoshikawa 2 , Hirofumi
Fujii 1,4
1 Functional Imaging Division, National Cancer Center Hospital East, Kashiwa, Chiba, Japan; 2 Faculty of Health
Sciences, Komazawa University, Setagaya, Tokyo, Japan; 3 Graduate School of Human Health Sciences, Tokyo
Metropolitan University, Arakawa, Tokyo, Japan; 4 Institute for Bioinformatics Research and Development-
Japan Science and Technology Agency, Chiyoda, Tokyo, Japan
We tested the SPECT-MRI fusion technique to visualize regional lymph nodes involved in subacute inflammation arising from the
lymphatic basin using a mouse model. Two to three weeks after the administration of Freund complete adjuvant to the foot pad, 99m Tc
phytate high-resolution SPECT images of the hind limb were obtained using a small animal SPECT scanner equipped with 4 detectors
with multi-pinhole collimators. These SPECT images were merged with MR images to provid precise anatomical information.
SPECT-MRI fusion images showed swollen popliteal lymph nodes and the accumulation of 99m Tc at the periphery, suggesting the
inhomogeneous distribution of macrophages within the swollen lymph nodes.
Diffusion MRI
Hall B Monday 14:00-16:00 Computer 54
14:00 3964. Validating Validators: An Analysis of DW-MRI Hardware and Software Phantoms
Paulo Rodrigues 1 , Vesna Prckovska 1 , W. L.P.M. Pullens 2 , Gustav J. Strijkers 3 , Anna
Vilanova 1 , Bart M. ter Haar Romeny 1
1 Biomedical Image Analysis, Eindhoven University of Technology, Eindhoven, Noord Brabant, Netherlands;
2 Maatricht Brain Imaging Center, Maastricht University, Maastricht, Limburg, Netherlands; 3 Department of
Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Noord Brabant, Netherlands
Diffusion Weighted MRI techniques such as Diffusion Tensor Imaging (DTI) and High Angular Resolution Diffusion Imaging
(HARDI) are emerging MRI techniques able to depict in-vivo brain’s connectivity map. There is a wide range of uses of these
techniques; however, their application in a clinical setting requires thorough validation. This work aims to validate DTI and HARDI
software phantoms, in regions of single and complex fiber bundles, w.r.t to hardware phantom and in-vivo human brain data.
Knowledge of the accuracy of synthetic data can improve the evaluation of such algorithms, and advance the employment of DTI and
HARDI into clinical environment.
14:30 3965. Diffusion Imaging and Tractography on a Hardware Model of the Human Optic
Chiasm
Wilhelmus LPM Pullens 1 , Alard Roebroeck 1 , Rainer Goebel 1
1 Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Limburg, Netherlands
The human optic chiasm is an interesting, complex fiber structure, hard to image in vivo. Based on the anatomy, a DW-MRI phantom
was constructed, offering the possibility to quantify tractography results, with little limits on imaging time, and it does not suffer from
motion or cardiac pulsation artifacts. A detailed analysis of Constrained Spherical Deconvolution and tensor reconstructions was done,
as well as quantitative (probabilistic) fiber tracking. These phantoms form ideal test objects to improve and validate imaging and
quantitative DW-MRI tractography on complex fiber structures such as the optic chiasm.