Short Tau and Fluid Attenuated Inversion Recovery - Video Lesson

Hey, everybody. Welcome to today's lesson on spin echo pulse sequences. This lesson focuses on two fast inversion recovery sequences, short tau inversion recovery or STIR, and fluid attenuated inversion recovery or FLAIR. These sequences are useful in identifying specific pathologies, so it is important to understand how they work. First, let's define fast inversion recovery. Fast inversion recovery is a broader category of MRI sequences where the main goal is to suppress specific tissue signals to enhance contrast. Remember, inversion recovery pulse sequences are characterized by a one hundred eighty degree inversion RF pulse followed by a ninety degree excitation pulse. The time between the one hundred eighty degree inversion pulse and the ninety degree excitation pulse is called the inversion time, t I. Because different tissues recover at different rates, this process enables selective suppression of certain tissue signals, which allows for a stronger signal