| In MRI scanning,the noise produced by the vibration of gradient coil has been affecting the comfort of patients,and even poses a safety risk to sensitive groups such as fetus and infant.Although the recommended noise level is less than 65 dB(A)in the case of newborn MRI hearing protection devices(such as earplugs and earphones),the noise level may be as high as125 – 130 dB(A)in 3T MRI scanning.In addition,it may not be applicable to the hearing protection method of using earplugs and earphones for newborns.The amplitude and polarity of gradient waveform used in single echo plane imaging(EPI)change very fast,so it is very effective to collect data quickly and effectively,but it will produce very high level noise.As EPI is a widely used sequence,a noise reduction solution in sequence design that can be applied to all kinds of platforms is expected.In this paper,,the effects of gradient waveform adjustment,echo spacing and parallel imaging on noise reduction are studied.Through the adjustment of gradient waveform and echo spacing(ESP),combined with parallel imaging and reconstruction technology,the noise of 7 dB(A)is reduced while maintaining a high SNR.In addition,in terms of validity,we quantitatively verified the image consistency and ADC value accuracy of traditional EPI-DWI sequence and optimized EPI-DWI sequence in the research of phantom and human body. |
