readout direction
Spatial axis along which MRI signal frequency encoding occurs during image acquisition, determining distortion characteristics.
Full Definition
The readout direction (also called frequency encoding direction) is one of the three spatial encoding dimensions in MRI acquisition that determines how spatial information is encoded in the acquired signal. This direction is particularly important in echo-planar imaging sequences where the choice of readout direction affects the pattern and severity of susceptibility and distortion artifacts. Common readout directions include anterior-posterior, left-right, and superior-inferior orientations. Understanding readout direction is crucial for optimizing image quality, minimizing artifacts in regions of interest, and implementing distortion correction algorithms in functional and diffusion MRI studies.
Usage
Usage note: Often abbreviated as RO in technical documentation.
In Context
- "The readout direction was oriented anterior-posterior to minimize susceptibility artifacts in the orbitofrontal cortex." — MRI protocol specification
- "Distortion correction algorithms require knowledge of the readout direction to accurately model geometric distortions." — Technical implementation guide