Site Differences inSite Differences in Kspace Filtering Kspace Filtering

and How They Explain and How They Explain Site Differences in Image Site Differences in Image

SmoothnessSmoothnessLee Friedman, Ph.D.Lee Friedman, Ph.D.The MIND InstituteThe MIND Institute

FIRST BIRN All Hands MeetingFIRST BIRN All Hands MeetingMarch 21, 2005March 21, 2005

Site Differences in SensitivitySite Differences in Sensitivity

Site Differences in SmoothnessSite Differences in Smoothness

Smoothness Predicts SensitivitySmoothness Predicts Sensitivity

http://www.revisemri.com/tutorials/intro_kspace1.htmDave Higgins

Google: kspace mri tutorial

The Voxel Point Spread FunctionThe Voxel Point Spread Function

Narrow PSFLess Smooth ImageMore Noisy Image

Less Sensitive to BOLD

Broader PSFMore Smooth Image

Less Noisy ImageMore Sensitive to BOLD

STAN 3T, DUKE 1.5T, DUKE 4.0T all GE IOWA GE 1.5T

IRVINE PICKER 1.5T ALL SIEMENS, BRIGHAM GE 3T

EPI SPIRAL

STAN 3T, DUKE 1.5T, DUKE 4.0TIOWA GE 1.5T IRVINE PICKER 1.5T

Recommendations for Multi-Center Recommendations for Multi-Center StudiesStudies

No Kspace Filters

Easy to implementHigher Spatial ResolutionLess SmoothMore NoisyLess SensitiveUgly Voxel PSF

All sites use same kspace filtering regimes

Rotationally SymmetricFermi FilterRadius = 32Width = 2.5

Hard to implementLower Spatial ResolutionMore SmoothLess NoisyMore SensitivePretty Voxel PSF