Preliminary Application Of CEST MRI In Brain Glioma Based On LOVARS Phase Mapping Method

Chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) technology has made certain progress of studying in stroke, brain glioma and so on, but interference effects caused by the RF pulse has been a problem in CEST MRI technique, such as direct saturation (DS) and magnetization transfer (MT) effects. LOVARS phase mapping method not only distinguished the CEST, MT and DS effects, reduced scanning time and Bo sensitivity, but also improved the contrast to noise ratio (CNR). This paper applies LOVARS phase mapping method to human brain glioma images. The main studying contents arc:(1) It is proved that the repeatability and reliability of LOVARS sequence is good through the analysis of the egg white phantom data collected by LOVARS sequence, which lays a foundation for the subsequent acquisition of brain glioma collected by LOVARS sequence.(2) This paper applies LOVARS phase mapping method to CEST MR imaging of eleven patients with brain glioma. The specific, implementation process is:select twelve images from the sequence of images of each brain glioma patient at first, and next convert the time domain to frequency domain by using fast Fourier transformation (FFT), in order to get real, imaginary and phase map. The experiment results show that the CNR of phase map is bigger than original image after using LOVARS phase mapping method, and it is easier to recognize tumor and normal regions, which is helpful to identify and diagnose the disease of patients, and to extract the tumor region.(3) Point at the problem which needs to select regions of interest (ROI) when give a confirmation of LOVARS sequence, this paper designs a ROI selection system. The system includes reading medical images, ROI selection and saving pixels of selected ROI, and it is convenient to doctors and researchers to the medical image processing, and it has some use value.