Fast Imaging Techniques (MRI) Essay Example | Topics and Well Written Essays - 1500 words

Fast Imaging Techniques (MRI) - Essay ExampleConsequently, the shortened duration of flat top reduces both ESP and the geometrical distortion of the image (Jezzard and Balaban, 1995, p.71). Another consequence of increasing the receiver bandwidth is faster imaging. Although increasing the receiver bandwidth allows faster imaging, it may also significantly reduce the SNR, and this practically leads to more noise outside the spectrum (Parrish, 2000, p.927). For example, as the bandwidth range is gradually growthd, the system may begin to sample more inherent noise together with the generated retrieve signal, thereby resulting in the fall of SNR. There are a number of ways that can generally be used to help recover the signals disordered as a result of a wider bandwidth during the optimization of image. Some of the choices include acquisition of more signal averages and improving the receiver coil technology. The first preference is, however, counter-productive because it may incre ase the amount of time needed to perform the overall scan while the second option if a good deal preferred because it helps maintain the lord objective of choosing EPI. Lastly, with regard to the required T2 weighted image, increasing the receiver bandwidth may reduce the effects of chemical shift artefacts on the image. According to Ra and bank (1993, p.145), this is because higher receiver bandwidth results in a wide range of resonant frequencies on which the distortion is spread in order to cover a little pixel range and minimize the geometric distortion. 2. Discuss the advantages and disadvantages of using segmentation in EPI. Segmentation is a new concept that has significantly made it realizable to use EPI on most of the conventional imaging systems where constraints related to signal to noise would have otherwise prevented EPI. Segmenting EPI is increasingly becoming more important to a number of its properties that ensure improved image quality as compared to the conven tional single shot EPI. For example, one of the potential benefits of segmentation is that it allows EPI to be able to effectively run on the conventional systems where single short EPI can not be used. This is because segmentation ensures less stress is placed on the gradients as contend to single short EPI and is therefore critically important in situations where by the available SNR and hardware makes it difficult to acquire all the necessary k-space data in the first place the elimination of the MR signal by the traverse relaxation (McRobbie et al., 2003, p.75). Another important advantage of section EPI is that it helps reduce the magnetic susceptibility of various artefacts. This is because phase errors often have less time to build up when segmented EPI as compared to single shot EPI. The shortening of echo train length also allows segmented EPI to be less prone to the effects of artefact variations. Segmentation can also be used to help reduce imaging distortion and enab le higher image resolution as compared to single shot EPI. The other key benefit of segmentation of EPI is the fact that it can be used to increase resolution. This is particularly attributed to the fact that segmented EPI have relatively short echo train length, thereby leading to increased spatial resolution. On the other hand, approach pattern single shot EPI usually have lower spatial