• Journal of radiological science and technology
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• v.39 no.1
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• pp.51-57
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• 2016

Acoustic noise during magnetic resonance imaging (MRI) is the main source for patient discomfort. we report our preliminary experience with this technique in neuroimaging with regard to subjective and objective noise levels and image quality. 60 patients(29 males, 31 females, average age of 60.1) underwent routine brain MRI with 3.0 Tesla (MAGNETOM Tim Trio; Siemens, Germany) system and 12-channel head coil. Q-$T_2$ and $T_2$ sequence were performed. Measurement of sound pressure levels (SPL) and heart rate on Q-$T_2$ and $T_2$ was performed respectively. Quantitative analysis was carried out by measuring the SNR, CNR, and SIR values of Q-$T_2$, $T_2$ and a statistical analysis was performed using independent sample T-test. Qualitative analysis was evaluated by the eyes for the overall quality image of Q-$T_2$ and $T_2$. A 5-point evaluation scale was used, including excellent(5), good(4), fair(3), poor(2), and unacceptable(1). The average noise and peak noise decreased by $15dB_A$ and $10dB_A$ on $T_2$ and Q-$T_2$ test. Also, the average value of heartbeat rate was lower in Q-$T_2$ for 120 seconds in each test, but there was no statistical significance. The quantitative analysis showed that there was no significant difference between CNR and SIR, and there was a significant difference (p<0.05) as SNR had a lower average value on Q-$T_2$. According to the qualitative analysis, the overall quality image of 59 case $T_2$ and Q-$T_2$ was evaluated as excellent at 5 points, and 1 case was evaluated as good at 4 points due to a motion artifact. Q-$T_2$ is a promising technique for acoustic noise reduction and improved patient comfort.

• The Journal of Korean Physical Therapy
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• v.21 no.3
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• pp.87-93
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• 2009

Purpose: TThis study examined the effect of repetitive magnetic stimulation (RMS) on the viability and proliferative response of human adipose tissue-derived stromal cells (hATSCs) in vitro. Methods: The hATSCs were cultured primarily from human adipose tissue harvested by liposuction and incubated in a $37^{\circ}C$ plastic chamber. The cells were exposed to a repetitive magnetic field using a customized magnetic stimulator (Biocon-5000, Mcube Technology). The RMS parameters were set as follows: repetition rate=10Hz, 25Hz (stimulus intensity 100%= 0.1 Tesla, at 4cm from the coil), stimulated time= 1, 5, and 20 minutes. Twenty four hours after one application of RMS, the hATSCs were compared with the sham stimulation, which were kept under the same conditions without the application of RMS. The cells were observed by optical microscopy to determine the morphology and assessed by trypan blue staining for cell proliferation. The apoptosis and viability of the hATSCs were also analyzed by fluorescence-activated cell sorting (FACS) analysis of Annexin V and MTT assay. Results: After RMS, the morphology of the hATSCs was not changed and the apoptosis of hATSCs were not increased compared to the sham stimulation. The viability of the cells was similar to the cells given the sham stimulation. Interestingly, the level of hATSC proliferation was significantly higher in all RMS groups. Conclusion: The application of RMS may not cause a change in morphology and viability of hATSCs but can increase the level of cell proliferation in vitro. RMS might be useful as an adjuvant tool in combination with stem cell therapy without adverse effects.

• Journal of radiological science and technology
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• v.32 no.2
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• pp.177-182
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• 2009

Purpose : This study presents the optimization of flip angle (FA) to obtain higher contrast to noise ratio (CNR) and lower specific absorption rate (SAR). Materials and Method : T1-weighted images of the cerebrum of brain were obtained from 50$^\circ$ to 130$^\circ$ FA with 10$^\circ$ interval. Signal to noise ratios (SNRs) were calculated for white matter (WM), gray matter (GM), and background noise. The proper FA was analyzed by T-test statistics and Kruskal-wallis analysis using R1 = 1- exp ($\frac{-TR}{T1}$) and Ernst angle cos $\theta$ = exp ($\frac{-TR}{T1}$). Results : The SNR of WM at 130$^\circ$ FA is approximately 1.6 times higher than the SNR of WM at 50$^\circ$. The SNR of GM at 130$^\circ$ FA is approximately 1.9 times higher than the SNR of GM at 50$^\circ$. Although the SNRs of WM and GM showed similar trends with the change of FA values, the slowdown point of decrease after linear fitting were different. While the SNR of WM started decreasing at 120$^\circ$ FA, the SNR of GM started decreasing at less than 110$^\circ$. The highest SNRs of WM and GM were obtained at 130$^\circ$ FA. The highest CNRs, however, were obtained at 80$^\circ$ FA. Conclusion : Although SNR increased with the change of FA values from 50$^\circ$ to 130$^\circ$ at 3T SE T1WI, CNR was higher at 80$^\circ$ FA than at the usually used 90$^\circ$ FA. In addition, the SAR was decreased by using smaller FA. The CNR can be increased by using this optimized FA at 3T MR SE T1WI.