Object ID: 00000018WIA30F3B770GYZ
Topic ID: id_40023126 Version: 1.2
Date: Mar 17, 2022 4:08:45 PM

Navigator troubleshooting tips

Figure 1. Trouble shooting tips for examples of Navigator patterns

Navigator waveform pattern	Cause	Action
Drift down	Patient specific	Wait 3-4 cycles and move the threshold up slightly, if needed.
Drift up	Patient specific	Move threshold up slightly at once (avoids accepting mid respiratory points).
Apnea	Patient specific	No action.
Abnormally small excursion	Patient specific	Reduce Navigator acceptance window.
Acceptable poor signal	The low navigator signal is due to inhomogeneity effects at the dome of the liver.	There is no need to change any Navigator parameters since the green waveform correctly reflects the respiratory status.
Low SNR	Saturation effect by imaging excitation.	There are three options to correct the saturation effect: From the Graphic Rx toolbar, increase the tracker thickness. For LAVA, LAVA-FLEX, 3D Dual Echo, there are two additional options: From the Navigator tab, click Navigator Signal Enhancement option. Reduce the flip angle.
Diaphragm is far from center of grayscale	Tracker is located too far away from diaphragm.	From the Graphic Rx viewport, center the tracker line between the diaphragm and the lung. For details, see: Navigator: acquire a body scan procedure Navigator: acquire a coronary scan procedure
Undesirable signal	Interference from any of the following signals: Heart Lung inflammation Subcutaneous fat Visceral fat Vessels	For LAVA, LAVA-FLEX, 3D Dual Echo, from the Navigator tab, click Navigator Signal Enhancement option. Reposition the tracker position to avoid undesired signal. For details about tracker position, see: Navigator: acquire a body scan Navigator: acquire a coronary artery scan

Navigator signal enhancement may reduce T1 contrast if a low flip angle (approximately 10 degrees) is used.