A Proposed Interleaved Echo Planer Imaging Technique for High Resolution fMRI

Abstract

An interleaved Echo Planar Imaging (EPI) fMRI technique has been proposed here for obtaining spatially high resolution activation map
overlaid on EPI image to reduce image acquisition time. First of all, the 2D and 3D anatomical high resolution and 3D + Time series (4D)
low resolution functional images have been reconstructed and normalized. Slice timing correction for avoiding disorder and motion
correction for small head motion during the scan has been provided using the post-processing image registration algorithms. The extent of
translational and rotational head movements in fMRI data that can be corrected has also been determined and observed that 1-2 mm of
translational and 2-40 (deg) of rotational head movement correction can be achieved. The effect of hemodynamic response (HDR) on the
neural activation has been observed and the relevant activation map has been found for correlation coefficient, r > 0.20. In order to obtain
highly reliable and noise-free activation map, spatial smoothing has been done using a Gaussian filter with different kernel width and 4 mm
filter was found to be best with acceptable SNR. Frequency selective temporal filtering of fMRI data has been done to avoid cardiac,
respiration and Cerebral Spinal Fluid (CSF) pulsation, which shows 0.10Hz upper cut-off frequency filtering is the most effective one.
Finally high resolution functional and anatomical reference image have been obtained at 3.0T using the interleaved EPI technique. This
fMRI analysis offers possibilities for improved neurological research and clinical neurosurgical applications.