Spin Echo MRI

**Semantic type:** Diagnostic Procedure

**Definition:** A magnetic resonance imaging (MRI) sequence that consists of an excitation pulse (90 degrees), a rephasing pulse (180 degrees), and a signal reading of the echo before the sequence repeats. In contrast to gradient echo sequences in which the signal decays quickly due to magnetic field inhomogeneities, spin echo sequences preserve the MRI signal for longer with the addition of the rephasing pulse.

**Synonyms:** - Spin Echo Magnetic Resonance Imaging