Readout Lobe Polarity

Readout Lobe Polarity is available for two Gradient Echo, 2D pulse sequences: multi-echo Fast GRE and multi-echo Fast SPGR.

• Enter 0 to turn on the alternating or bipolar gradient lobe. The TR is shorter than if it is set to 1, thus the scan time is shorter. The shorter scan time is a tradeoff for some discrepancy between the positive and negatives echoes due to system inhomogeneities, eddy currents, etc.
• Enter 1 to turn on the positive gradient lobe. The images are less sensitive to inhomogeneities, eddy currents, etc. This results in a longer TR and thus a longer scan time in comparison to when the gradient lobe polarity is set to 0.