TRADITIONAL POSTER - ismrm

Poster Sessions
793. Characterization of Trabecular Orientation in Chicken Femur by Multi-Directional SPENT (Sub-Pixel
Enhancement of Non-Uniform Tissue)
Bailiang Chen 1 , Bernard Siow 2 , David Carmichael 1,3 , Freddy Odille 2 , Roger Ordidge 1 , Andrew Todd-
Pokropek 1
1 Medical Physics and Bioengineering, University College London, London, United Kingdom; 2 Centre for Medical Image Computing,
University College London, London, United Kingdom; 3 Institute of Neurology , University College London, London, United
Kingdom
The recently proposed SPENT sequence can provide direction specific information based on the sub-voxel structural uniformity of a sample. Analogous to
diffusion tensor imaging, given a voxel with a local anisotropic structure (e.g. trabecular bone), it is possible to characterize the orientation of sub-pixel
micro-structure by applying SPENT with multiple directions. A 6-direction SPENT series was applied to a chicken femur head in order to characterize its
trabecular bone orientation by reconstructing a 2D tensor in each voxel. Both tensor statistics and eigensystems were computed and showed good qualitative
agreement with data from a subsequent micro-CT acquisitions.
794. The Effect of Freezing on Measurements of Trabecular Bone Structure Based on NMR Spectroscopy
Viktoria Prantner 1 , Hanna Isaksson 1 , Johanna Närväinen 2 , Eveliina Lammentausta 3 , Olli HJ Gröhn 2,4 ,
Jukka S. Jurvelin 1
1 Department of Physics, University of Kuopio, Kuopio, Finland; 2 A.I. Virtanen Institute for Molecular Sciences, University of
Kuopio, Kuopio, Finland; 3 Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland; 4 Biomedical Imaging Unit,
University of Kuopio, Kuopio, Finland
NMR is a potential tool for the assessment of trabecular bone structure. Since trabecular bone provides a negligible NMR signal, the indirect evaluation of
the trabecular bone structure is based on the analysis of water and fat components in the bone marrow. Earlier studies have revealed that freezing affects the
bone marrow structure, suggesting there may be changes in the molecular structure. The aim of the current study is to investigate the effect of freezing on
trabecular bone and bone marrow, as assessed by NMR spectroscopy.
795. Performance of Two Spin-Echo Sequences for Quantitative Structure Analysis of Trabecular Bone
Michael Jeffrey Wald 1 , Jeremy Francis Magland 1 , X. Edward Guo 2 , Felix Werner Wehrli 1
1 Laboratory for Structural NMR Imaging, University of Pennsylvania Medical Center, Philadelphia, PA, United States; 2 Bone
Bioengineering Laboratory, Columbia University, New York, United States
The performance of two spin-echo based pulse sequences for imaging trabecular bone microstructure are evaluated at 1.5T in seven fixed, cadaveric distal
tibia specimens. SNR efficiency and sensitivity of image-derived trabecular bone structural parameters to variations in bone quality as assessed by µCT were
investigated. Inter- pulse sequence correlations suggest similar structural sensitivity, while comparisons to µCT reveal good sensitivity but large deviations
in absolute values between modalities.
796. Ultra-Short TE (UTE) Imaging of Skull and a Quantitative Comparison of Skull Images Obtained
from MRI and CT
Liya Wang 1 , Xiaodong Zhong 2 , Longjiang Zhang 3 , Diana Tiwari 1 , Hui Mao 1
1 Department of Radiology and Emory Center for Systems Imaging, Emory University School of Medicine, Atlanta, GA, United
States; 2 MR R&D Collaborations, Siemens healthcare, Atlanta, GA, United States; 3 Department of Radiology, Jinlin Hospital and
Nanjing University College of Clinical Medicine, Nanjing, Jiangsu, China
This study provided a quantitative evaluation of skull images obtained using UTE MRI and a direct comparison to those from CT. The skull thickness
measured from UTE images showed good agreement with those obtained from CT images in different slices. There is also a good correlation between the
thickness measurements obtained from CT and UTE images. Signal intensity based evaluation showed that there is no statistical difference between UTE
and CT images in outer, inner layer and diploe of the skull. The comparison of bone UTE MRI and CT of skull suggests that UTE images match closely with
CT images.
797. MR Imaging Detects Impaired Angiogenesis and Trabecular Bone Formation During Endochondral
Bone Growth Mediated Through PKBalpha/Akt1 in Gene Dosage Dependent Manner
Katrien Vandoorne 1 , Jeremy Magland 2 , Vicki Plaks 1 , Inbal E. Biton 3 , Amnon Sharir 4,5 , Elazar Zelzer 4 ,
Felix Wehrli 6 , Brian A. Hemmings 7 , Alon Harmelin 3 , Michal Neeman 1
1 Biological Regulation, Weizmann Institute, Rehovot, Israel; 2 Department of Radiology, University of Pennsylvania Health System,
Philadelphia, PA, United States; 3 Veterinary Resources, Weizmann Institute, Rehovot, Israel; 4 Molecular Genetics, Weizmann
Institute, Rehovot, Israel; 5 The Laboratory of Musculoskeletal Biomechanics and Applied Anatomy, Koret School of Veterinary Medi,
Hebrew University of Jerusalem, Rehovot, Israel; 6 Department of Radiology, University of Pennsylvania Health System, Philadelphia,
PA, Israel; 7 Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
Since infiltration of the newly formed blood vessels is required for endochondral bone formation, and PKBalpha/Akt1 mediates intracellular signaling of
angiogenesis, we postulated that a vascular deficiency at the site of the long bones could contribute indirectly to impaired bone development in
PKBalpha/Akt1 deficient mice. Our study demonstrated using macromolecular DCE-MRI in vivo and ex vivo µCT and µMRI, vascular and bone
developmental defects in PKBalpha/Akt1 null mice, and remarkably also in heterozygous mice, lacking a single copy of the gene.