• Investigative Magnetic Resonance Imaging
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• v.3 no.2
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• pp.154-158
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• 1999

Purpose : The purpose of this study was to find the optimum TE value for enhancing $T_2^{*}$ weighting effect and minimizing the SNR degradation and to compare the BOLD effects according to the changes of TE in 1.5T and 3.0T MRI systems. Materials and Methods : Healthy normal volunteers (eight males and two females with 24-38 years old) participated in this study. Each volunteer was asked to perform a simple finger-tapping task (sequential opposition of thumb to each of the other four fingers) with right hand with a mean frequency of about 2Hz. The stimulus was initially off for 3 images and was then alternatively switched on and off for 2 cycles of 6 images. Images were acquired on the 1.5T and 3.0T MRI with the FLASH (fast low angle shot) pulse sequence (TR : 100ms, FA : $20^{\circ}$, FOV : 230mm) that was used with 26, 36, 46, 56, 66, 76ms of TE times in 1.5T and 16, 26, 36, 46, 56, 66ms of TE in 3.0T MRI system. After the completion of scan, MR images were transferred into a PC and processed with a home-made analysis program based on the correlation coefficient method with the threshold value of 0.45. To search for the optimum TE value in fMRI, the difference between the activation and the rest by the susceptibility change for each TE was used in 1.5T and 3.0T respectively. In addition, the functional $T_2^{*}$ map was calculated to quantify susceptibility change. Results : The calculated optimum TE for fMRI was $61.89{\pm}2.68$ at 1.5T and $47.64{\pm}13.34$ at 3.0T. The maximum percentage of signal intensity change due to the susceptibility effect inactivation region was 3.36% at TE 66ms in 1.5T 10.05% at TE 46ms in 3.0T, respectively. The signal intensity change of 3.0T was about 3 times bigger than of 1.5T. The calculated optimum TE value was consistent with TE values which were obtained from the maximum signal change for each TE. Conclusion : In this study, the 3.0T MRI was clearly more sensitive, about three times bigger than the 1.5T in detecting the susceptibility due to the deoxyhemoglobin level change in the functional MR imaging. So the 3.0T fMRI I ore useful than 1.5T.

• Journal of Music and Human Behavior
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• v.16 no.1
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• pp.73-88
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• 2019

This research was conducted to compare the rhythm reproduction abilities between older adults with and without mild cognitive impairment (MCI) and analyze the abilities depending on the rhythm idiom. Participants between 60-85 years of age were recruited from senior community centers, dementia prevention centers, and senior welfare centers. A total of 57 participants were included in this study: 27 diagnosed with MCI and 30 healthy older adults (HOA). The experiment was conducted individually in a private room in which a participant was given random binary time rhythm idioms and instructed to reproduce the rhythmic idioms with finger tapping. Each participant's beat production was recorded with the Beat Processing Device (BPD) for iPad. BPD calculated rhythm reproduction as measured through rhythm ratio and error among beats. Results showed marginal differences between the two groups in terms of mean scores of rhythm reproduction abilities. In terms of the rhythm ratio among beats, both groups' highest rhythm reproduction rate was for <♩ ♩>, and their lowest reproduction rate was for <♩. ♪>. In conclusion, there was no significant difference in rhythm reproduction ability between the HOA and MCI groups. However, the study found an interesting result related to performance level of rhythmic idioms. This result provides therapeutic insight for formulating rhythm tasks for older adults.