基于Hartley变换的磁共振成象(英文)

HARTLEY TRANSFORM BASED MAGNETIC RESONANCE IMAGING

许多磁共振成象的应用场合需要利用正交双通道来采集一个具有时间和空间分辨力的图象序列．传统的基于Fourier变换的成象方法，一方面，图象序列的重建时各帧图象是独立地进行重建的，因而图象序列的时间分辨力受到空间编码的限制；另一方面，来自两个通道之间的Fourier空间数据分别备采集和重建，然后求模取和得到磁共振图象，因而影响了磁共振成象的效率和简单性．为此本文提出了基于Hartley变换的磁共振成象技术．这一技术是利用了两个重要的事实，即磁共振图象是实函数和大多数磁共振图象的空域范围是不变的．这两个事实有利于通过减少稳定信息的重复编码来改善磁共振成象的分辨力和效率，以及减少数据采集系统的复杂性．这种方法可以被证明能够应用于动态脑功能成象．

Many magnetic resonance imaging (MRI) applications requires the acquisitionof a time series of images with both spatial and temporal high-resolution as well as with anorthogonal dualchannel. In conventional Fourier transform (FT) based imaging methods, onthe one hand, each of these images is independently reconstructed from a frame of spatialencodings, so that temporal resolution is limited by the number of the spatial encodings ofeach frame collected in the case of given spatial resolution, or one has to sacrifice spatial resolution to obtain temporal resolution. On the other hand, the dual-channel data in Fourierspace are independently acquired and reconstructed, then the MR image is obtained by thesquare modulus, so that the simplicity and efficientibility of computation are affected. Inthis paper, Hartley transform (HT) based MR imaging technique are proposed to addressthis problem. This technique makes use of the fact that MR images are real, and the supportextent of high-resolution image (morphology) does not change from one image to anotherin most time- sequential imaging problem, and which helps to improve imaging efficiencyand resolutions, and to reduce the complexity of MRI system over the conventional Fourierimaging method by eliminating the repeated encodings of this stationary information. Thismethod should prove useful for a variety of dynamic imaging applications such as dynamicstudies of functional brain imaging.