National Alliance for Medical Image Computing http://na-mic.org
Ising Prior in fMRI detection
• Junmo Kim
• John Fisher
• Eric Cosman
• Wanmei Ou
• Polina Golland
National Alliance for Medical Image Computing http://na-mic.org
GLM / Ising
Exact MAP Activity Detection in fMRI Using a GLM with an Ising
Spatial Prior
Eric Cosman, Jr., Wanmei Ou, John Fisher, William Wells
National Alliance for Medical Image Computing http://na-mic.org
GLM / Ising…
• Alternative model for noise reduction
• Ising MRF prior model
• In GLM / Hypothesis Test
• Fast exact solution: Portius, Grieg
• Result is F-statistic (threshold at)
National Alliance for Medical Image Computing http://na-mic.org
National Alliance for Medical Image Computing http://na-mic.org
GLM / Ising Results
Eric Cosman, Jr., Wanmei Ou
National Alliance for Medical Image Computing http://na-mic.org
GLM / Ising…
• Wanmei Ou– MIT MS Project with Polina Golland– Empirical Characterization of fMRI
detectors• Larry Panych data• GLM / MI• MARKOV spatial models
– Exact– Approximate
National Alliance for Medical Image Computing http://na-mic.org
GLM / Ising: Empirical Results
Eric Cosman, Jr., Wanmei Ou
•ROC analysis on realistic synthetic data
•Low SNR regime: Gaussian Blur is Better
•High SNR regime: Ising Prior is Better
National Alliance for Medical Image Computing http://na-mic.org
GLM Combined with Ising Model
• Eric Cosman et al. MICCAI 04
• Extends GLM hypothesis testing approach to include Ising Prior model on activations
National Alliance for Medical Image Computing http://na-mic.org
Synthetic Comparison with Gaussian Smoothing
National Alliance for Medical Image Computing http://na-mic.org
MI-Based fMRI Activation Detection
• Standard Modeling Assumptions (GLM):– Activating Voxel intensities are proportional
to protocol with added Gaussian Noise
• MI approach:– A Voxel is declared active if it is not
statistically independent of protocol• As Measured by MI
– Andy Tsai
National Alliance for Medical Image Computing http://na-mic.org
Kim MS: MI with Ising Prior on Activations
• Demonstrate that MI is optimal test statistic for Likelihood Ratio Test of independence
• Use Likelihood to facilitate combination with Ising prior model on activation
• Show that estimator can be solved in polynomial time
National Alliance for Medical Image Computing http://na-mic.org
Verb-Association Test Results
Provided by Eric Cosman,Jr.
National Alliance for Medical Image Computing http://na-mic.org
Representative Voxels
Provided by Eric Cosman,Jr.
NA-MICNational Alliance for Medical Image Computing http://na-mic.org
Bayesian Population Inference for the Multivariate Autoregressive Process
Eric Cosman
1/19/05
IPMI 05?, PhD 05
National Alliance for Medical Image Computing http://na-mic.org
•The end