ELECTRONIC POSTER - ismrm

14:30 3409. Spatiotemporal Exploratory Analysis of FMRI Data
Radu Mutihac 1
1 Electricity & Biophysics, University of Bucharest, Bucharest, Romania
Spatiotemporal characteristics of brain activity are frequently unknown and variable, which preclude their evaluation by confirmatory
methods only. Revealing unanticipated or missed patterns of activation, exploratory data analysis (EDA) allows to improve or even to
change the original hypotheses. Artifactual behavior that EDA may easily discover could raise questions on data appropriateness, if
additional preprocessing steps are required, or if the preprocessing employed has introduced spurious effects. Spatial independent
component analysis (sICA) and temporal fuzzy cluster analysis (tFCA) were comparatively investigated as typifying EDA of
neuroimaging data.
15:00 3410. Spatial Variation of BOLD Contrast in the Activated ROI Is Correlated with Voxel-
Wise Gray Matter Volume Fraction
Wanyong Shin 1 , Hong Gu 1 , Qihong Zou 1 , Pradeep Kurup 1 , Yihong Yang 1
1 Neuroimaging Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore,
MD, United States
In this study, we investigate spatial variations of BOLD contrast (β) within individual subjects and correlate it with voxel-wise T1 and
fractional volume (fv) of each tissue component using a new brain segmentation technique, FRASIER. Our data show that spatial ¥â
variation within individual subjects in a ROI activated by a visual task is highly correlated with T1 and fractional volume of GM, as
well as resting-state fluctuation amplitude (RSFA). The dependency (slop of the linear regression), however, varies over subjects.
These findings may be used to calibrate BOLD signals for improving sensitivity and specificity in detecting brain activity.
15:30 3411. Comparison of the Location and Extent of BOLD Activation in High Spatial
Resolution SE and GE FMRI of the Motor Cortex at 7T
Jack Harmer 1 , Rosa Maria Sanchez-Panchuelo 1 , Richard W. Bowtell 1 , Susan T. Francis 1
1 Sir Peter Mansfield Magnetic Resonance Centre, The University of Nottingham, Nottingham, Nottinghamshire,
United Kingdom
Gradient-echo (GE) and spin-echo (SE) EPI based fMRI is used to compare SE and GE BOLD responses at high field strength (7T)
and resolution (1.5mm isotropic) using a motor paradigm. We investigate CNR, fractional signal change as a function of echo time,
spatial specificity of SE BOLD and the localisation of GE and SE activation in relation to underlying venous blood vessels. Robust
activation was detected using both SE and GE EPI. A higher proportion of GE activation was found to occur in voxels classified as
having a high venous contribution than in SE data.
Tuesday 13:30-15:30 Computer 19
13:30 3412. A Theoretical Direct Neuronal Detection Study to Estimate Percentage Local Field
Perturbations
Syed Muhammad Anwar 1 , Greg Cook 1 , Martyn Paley 2
1 Electronic and Electrical Engineering, University of Sheffield, Sheffield, United Kingdom; 2 Academic
Radiology, University of Sheffield, Sheffield, United Kingdom
Direct neuronal detection (DND) of nerve impulses using MR techniques to image brain activity is currently under study as an
alternative to BOLD based functional MRI. This work theoretically estimates the percentage local signal perturbations caused by the
weak transient neuronal fields, and the effect of various axonal firing delays on these perturbations is also studied. The modelling
suggests that detection of neuronal fields should be within the capability of current MR technology, and that better post processing
may be required for more reliable and reproducible results.
14:00 3413. Investigating the Earthworm (Lubricus Terrestris) as a Model for NcMRI at 9.4T
Martyn Paley 1 , Steven Reynolds 1 , LiSze Chow 1 , Syed Anwar 2 , Greg Cook 2
1 Academic Radiology, University of Sheffield, Sheffield, Yorkshire, United Kingdom; 2 Electronics and
Electrical Engineering, University of Sheffield, Sheffield, Yorkshire, United Kingdom
The feasibility of performing ncMRI in the intact resting earthworm has been investigated using a high resolution probe at 9.4T.
14:30 3414. Optimization of Echo Time in Direct Detection of Neuronal Currents with MRI
Qingfei Luo 1 , Jia-Hong Gao 1
1 The University of Chicago, Chicago, IL, United States
To detect the weak neuronal current MRI (ncMRI) signal, the imaging parameters (e.g., echo time) need to be optimized to achieve
the maximum detection sensitivity. In this study, by theoretical modeling, we estimated the optimal echo time (TE) in a typical invivo
ncMRI experiment using gradient-echo EPI pulse sequence. The results show that the optimal TE for detecting ncMRI
magnitude/phase signal is 92/56ms in human brain at 3T. Also, the difference of optimal TE between magnitude and phase signals
suggests that a dual-echo pulse sequence should be used to achieve the highest sensitivity to both signals in a MRI scan.