navigator gating
MRI technique using real-time tracking of diaphragmatic motion to synchronize image acquisition with respiratory position.
Full Definition
Navigator gating is an advanced MRI technique that compensates for respiratory motion by monitoring the position of the diaphragm in real-time and acquiring data only when the diaphragm is within a predetermined acceptance window. A pencil-beam radiofrequency pulse tracks the diaphragm-lung interface, typically at the right hemidiaphragm, providing motion information without additional breath-holding requirements. This technique is particularly valuable for high-resolution cardiac imaging sequences that require long acquisition times, such as coronary MRA, late gadolinium enhancement, and T1 mapping. Navigator gating significantly improves image quality by reducing respiratory motion artifacts while maintaining patient comfort during extended scanning periods.
Usage
Usage note: Specify acceptance window size (typically 3-7mm) when documenting navigator settings.
In Context
- "Navigator gating with a 5mm acceptance window was employed for the high-resolution LGE sequence." — MRI protocol description
- "Poor navigator gating efficiency resulted in prolonged scan time for the coronary MRA acquisition." — Technical imaging note