Research On The Post Processing Technology For Chemical Exchange Saturation Transfer MeLOVARS Imaging Method

Magnetic resonance imaging (MRI) technology has no radiation damage, strong penetrability, high soft tissue contrast and can provide a variety of diagnostic information, which make it plays an important role in medical imaging diagnosis. However, inherent low sensitivity and low specificity of MRI limit the early diagnosis and discovery of the diseases, such as tumors. The researchers proposed chemical exchange saturation transfer (CEST) MRI technique, which can improve its sensitivity and specificity of imaging.As a new MRI contrast mechanism, CEST received extensive attention of researchers. But the current methods for detecting and quantitative analysis of the contrast mechanism mostly have low image quality and efficiency, which lead to the measurement of the contrast to noise ratio (CNR) decreased and the CEST contrast detection effected.To solve the above problems, this paper takes saturation pulse parameters for the modulation strategy, using Multi-echo Length and Offset Varied Saturation (MeLOVARS) imaging method to enhance contrast detection. This method reads water signal several times during the saturation preparation period within one TR and obtains multiple saturation weighted images, which not only shortens the scan time, but also combines different methods to improve the image quality and enhance the CEST contrast effect.This paper makes experiments on mice brain glioblastoma and obtains that CEST contrast effect of MeLOVARS imaging method is better than conventional CEST imaging method, afterwards, in order to improve the image quality of MeLOVARS imaging method and enhance the CEST contrast effect, it uses the principal component analysis (PCA) method to reduce the dimensionality of water signal mapping obtained from different saturation time and improve the CNR. Then for the presence of asymmetric conventional quantization of MeLOVARS imaging method influenced by other asymmetric composition, this article uses the improved asymmetric quantization in the process of MeLOVARS imaging method and compares to the conventional asymmetric quantization, which proved that the improved quantization method is more suitable for vivo application research. Finally, according to data processing is tedious and time consuming by MeLOVARS method, this paper designs the CEST Z spectrum analysis display system, which provides two methods for selecting ROI and is convenient for researchers to use the MeLOVARS imaging method in clinical studies.