IMPROVEMENT OF FUNCTIONAL MAGNETIC-RESONANCE IMAGES BY PRETREATMENT OF DATA

Functional magnetic resonance images of the brains of subjects perform ing the finger-tapping paradigm were made using a conventional techniq ue. Two threshold values for the pixels were obtained by analysing pix el by pixel the distributions of the means and variances of each subje ct's images for 20 consecutive scans, both while performing the task a nd while at rest. Considerable signal improvement in the final images was achieved by removing from our data all pixels beyond these thresho ld values (mean less than or equal to 16 and variance greater than or equal to 7).