Reproducibility of Hemispheric Language Dominance by Noun, Verb, Adjective and Adverb Generation Paradigms in Functional Magnetic Resonance Imaging of Normal Volunteers

Song, In Chan; Chang, Kee Hyun; Chung, Chun Kee; Lee, Sang Hyun; Han, Moon Hee

Abstract

PURPOSE: We investigated the reproducibility of language lateralization by 4 different word generation paradigms or the rest contents in each paradigm using functional magnetic resonance imaging in normal volunteers.
MATERIALS AND METHODS
Nine normal volunteers with left-handedness (mean age: 25 yrs) were examined on a 1.5T MR unit using a single-shot gradient echo epibold sequence. Four different word generation paradigms of noun, verb, adjective and adverb were used in each normal volunteer for investigating language system. In each paradigm, two different rest contents consisted of only seeing the "+" symbol or reading the meaningless letters. Each task consisted of 96 phases including 3 activations and 6 rests of 2 different contents. Two activation maps in one task were obtained under two different rest contents using the correlation method. We evaluated the detection rates of Broca and Wernicke areas and the differences of language lateralization among four different word generation paradigms, or between the rest contents.
RESULTS
The detection rates of Broca and Wernicke areas were over 67% in 4 different language paradigms and there was no significant difference of them among language paradigms, or between two different rest contents. Language dominances, in all 4 different language paradigms, were shown to be consistent in 66%, but were contrary with language paradigms in some subjects. The rest contents made no significant effect on dominant language dominance determination, but the success rates of the dominant language dominances determined from 4 language paradigms were higher in reading the meaningless letter (100%, n=9) than in only seeing "+" on screen at the rest task (78%, n=7).
CONCLUSION
High detection rates of Broca and Wernicke areas and high reproducibility of hemispheric language dominance in 4 different language paradigms showed functional MR imaging of our word generation paradigms was reliable and may be clinically useful. However, some inconsistency of hemispheric language dominance with language paradigms or the rest contents suggests that robust and reliable determination of language lateralization may need the performance of different paradigm types or the consideration of rest contents.