It is well known that data accquisition times and image reconstruction procedures in conventional magnetic resonance imaging (MRI) are usually long. For time dependent phenomena, such as sample motion, respiration, blood flow pulsation and others, faster accquision times are desirable to avoid ghosting artifacts. Over the last two decades, a great number of fast and ultra-fast MRI methods have been proposed that greatly reduce the accquision times. One of them is the echo-planar imaging (EPI) method which uses a single excitation scheme to scan entirely the k-space in a very short time. In the initial sections of this work we will supply the reader with a brief description of the image reconstruction procedures for the conventional MRI sequence and four different schemes of the EPI method. However, our main objective is to propose a modified version of the spin-echo EPI method, suggesting a sequence with the use of a constant phase encoding gradient.
