echo-planar imaging
Rapid MRI acquisition technique that captures an entire image in a single excitation, commonly used for functional and diffusion imaging.
Full Definition
Echo-planar imaging (EPI) is a rapid magnetic resonance imaging technique that acquires an entire image following a single radiofrequency excitation pulse. This method dramatically reduces scan time compared to conventional imaging sequences, making it particularly valuable for time-sensitive applications such as functional MRI (fMRI) and diffusion-weighted imaging. EPI achieves rapid acquisition by rapidly switching readout gradients to sample multiple lines of k-space after each excitation. However, this speed comes at the cost of increased susceptibility to artifacts, including distortion, signal dropout, and motion sensitivity, which require careful consideration in image interpretation and protocol optimization.
Usage
Usage note: Hyphenate as compound modifier; commonly abbreviated as EPI in technical contexts.
In Context
- "The functional study utilized echo-planar imaging with a 2-second temporal resolution." — Methods description
- "Echo-planar imaging sequences require shimming to minimize susceptibility artifacts." — Technical protocol