fMRI of the Motor Speech Center Using EPI

ABSTRACT

PURPOSE: To evaluate the feasibility of functional MR imaging(fMRI) using the echo-planar imaging (EPI)technique to map the motor speech center and to provide the basic data for motor speech fMRI during internal wordgeneration. MATERIALS AND METHODS: This study involved ten young, healthy, right-handed volunteers (MF=82 ;Age 21-27) ; a 1.5 T whole body scanner with multislice EPI was used. Brain activation was mapped using gradientecho single shot EPI(TR/TE of 3000/40, slice numbers 6, slice thickeness 10 mm, no interslice gap, matrix numbers128x128, and FOV 30x30). The paradigm consisted of a series of alternating rest and activation tasks, repeatedeight times. During the rest task, each of ten Korean nouns composed of two to four syllables was showncontinuously every 3 seconds. The subjects were required to see the words but not to generate speech, whereasduring the activation task, they were asked to internally generate as many words as possible from each of tennon-concrete one-syllabled Korean letters shown on the screen every 3 seconds. During an eight-minute period, atotal of 960 axial images were acquired in each subject. Data were analyzed using the Z-score(p<0.05), andfollowing color processing, the activated signals were overlapped on T1-weighted images. The location of theactivated area, mean activated signal intensity change (%), mean activated pixel numbers, and the presence ofcyclic change in signal intensity were evaluated. RESULTS: In seven subjects, activation was observed in the leftBroca's area and its adjacent areas(Brodmann areas 44, 45, 46, 6 and 10) ; in three of the seven, activation inBroca's areas was bilateral. In two of the remaining three subjects, the medial portion of the frontal lobe wasactivated, while in the other, there was no significant signal change in any area. Mean activated signal changewas 2.6+/-1.3% in the left Broca's area and 1.2+/-1.7% in the right, while the mean number of activated pixels was67+/-46 in the left area and 23+/-33 in the right. Periodic cyclic signal change according to rest and activationwas seen in the left Broca's area in four subjects, in the bilateral Broca's area in two, and in the medialportion of the frontal lobe in two. CONCLUSION: The results of this study indicate that in most subjects, fMRIusing EPI can effectively map the motor speech center. The data obtained may be useful for the clinicalapplication of fMRI.