There several imaging techniques that may be used to shorten the image acquisition time without shortening TR. Two techniques, fractional Nex imaging and fractional echo imaging, are presented in this section, while others will be presented in subsequent sections in this chapter. Before fractional Nex or fractional echo imaging can be understood, it is first necessary to examine a relationship between the data in different halves of k -space. K -space data is made up of complex data representing the M x and M y components of magnetization. The complex data in the right half of k -space is the complex conjugate of the data in the left half of k -space. Similarly, the data in the top half of k -space is the complex conjugate of the data in the bottom half of k -space. Fractional Nex Imaging Fractional Nex imaging takes advantage of this complex conjugate relationship between the top and bottom halves of k -space to reduce the number...