An experimental study on MR imaging of acute intracerebral hematoma: comparative analysis between high-field(2.0 T) and medium-field (0.5 T) images

This paper studies problematic of a mechanical system composed of different coupled parts submitted to a high speed shock and proposes analysis of anti vibratory passive and active methods based on an experimental and theoretical coupled approach. After a shock, different parts of the system oscillate. If one of them is excited at a particular frequency, such as its proper frequency, important oscillations appear and can lead to the deterioration of the system by introducing important stresses. In this paper, we propose an analysis in order to understand this kind of problem and what we can do to avoid it. Firstly, we discuss problematic and we expose the studied system. In a second time, we develop two approaches of modeling that allow us to understand the phenomenon by carrying out numerical simulations. Then cross checking of model is completed via experimental study on drop test bench. Passive minimization method of vibrations based on experimental and theoretical coupled approach is exposed. Finally, a comparative analysis of different methods of control and experimental results of controlled system are presented.

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Spinal cord grey matter lesions in multiple sclerosis detected by post-mortem high field MR imaging

Multiple Sclerosis Journal ◽

10.1177/1352458508096876 ◽

2008 ◽

Vol 15 (2) ◽

pp. 180-188 ◽

Cited By ~ 49

Author(s):

CP Gilmore ◽

JJG Geurts ◽

N Evangelou ◽

JCJ Bot ◽

RA van Schijndel ◽

...

Keyword(s):

Spinal Cord ◽

White Matter ◽

Mr Imaging ◽

High Field ◽

Grey Matter ◽

Great Majority ◽

Proton Density ◽

Post Mortem ◽

Mr Images ◽

The Brain

Background Post-mortem studies demonstrate extensive grey matter demyelination in MS, both in the brain and in the spinal cord. However the clinical significance of these plaques is unclear, largely because they are grossly underestimated by MR imaging at conventional field strengths. Indeed post-mortem MR studies suggest the great majority of lesions in the cerebral cortex go undetected, even when performed at high field. Similar studies have not been performed using post-mortem spinal cord material. Aim To assess the sensitivity of high field post-mortem MRI for detecting grey matter lesions in the spinal cord in MS. Methods Autopsy material was obtained from 11 MS cases and 2 controls. Proton Density-weighted images of this formalin-fixed material were acquired at 4.7Tesla before the tissue was sectioned and stained for Myelin Basic Protein. Both the tissue sections and the MR images were scored for grey matter and white matter plaques, with the readers of the MR images being blinded to the histopathology results. Results Our results indicate that post-mortem imaging at 4.7Tesla is highly sensitive for cord lesions, detecting 87% of white matter lesions and 73% of grey matter lesions. The MR changes were highly specific for demyelination, with all lesions scored on MRI corresponding to areas of demyelination. Conclusion Our work suggests that spinal cord grey matter lesions may be detected on MRI more readily than GM lesions in the brain, making the cord a promising site to study the functional consequences of grey matter demyelination in MS.

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