Experience of Functional MRI Protocol in King Chulalongkorn
Memorial Hospital [KCMH] for Thai Language Lateralization
Phattharachuda Chosakun MD1, Theerachai Chaitusaney MD1, Yothin Rakvongthai PhD2, Sukalaya Lerdlum MD2
Affiliation :
1 Department of Radiology, King Chulalongkorn Memorial Hospital, Thai Red Cross Society and Division of Diagnostic Radiology,
Department of Radiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
2 Department of Radiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
Objective : To investigate the effects of statistical thresholding and to determine an optimal functional magnetic resonance imaging
[fMRI] statistical threshold for Thai language lateralization.
Materials and Methods : The present study was prospective descriptive study of twenty Thai native speaker right-handed healthy
volunteers performed Thai verb and word generation paradigms during 3T fMRI. Bihemispheric activation difference of language
region of interests was calculated for laterality index [LI] through ranks of statistical threshold, from the threshold that generated
an empty map to the minimal threshold with p-value less than 0.05.
Results : LI of both verb generation and word generation paradigms tended to rise in higher statistical thresholds. In two subjects,
shifted of LI from co-dominant to left dominant were found as an effect of statistical thresholding on both paradigms. A threshold
(t-value) of 7 in verb generation paradigm and a threshold (t-value) of 6 in word generation paradigm signi(cid:976)icantly increased mean
LI (with p-value 0.004 and 0.003, respectively) and categorized 95% of the subjects as left hemispheric dominance.
Conclusion : LI varies across different statistical thresholds. Optimal thresholds (t-value) for language lateralization are 7 in Thai
verb generation and 6 in Thai word generation paradigms.
Keywords : Functional MRI, fMRI, Statistics, Threshold, Language lateralization, LI, Dominant hemisphere, Right-handedness, Thai
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