MT Frequency Offset

Magnetization Transfer improves contrast between blood flow and surrounding tissue by saturating tissues containing significant amounts of protein. Magnetization Transfer takes advantage of an energy exchange process that occurs between bound fat and unbound water nuclei. This is achieved by applying a large saturation pulse off center frequency.

In a Spin Echo sequence, Magnetization Transfer increases the conspicuity between brain parenchyma and tumor. For 3D TOF, Magnetization Transfer increases contrast between blood and brain parenchyma. In both cases, the brain tissue produces less signal; therefore, it provides better contrast between either vessel/brain or tumor/brain.

Use Magnetization Transfer to increase cord-to-CSF contrast or to enhance fat-to-cord difference. Fat-to-nerve contrast increases, so lesions in the nerve roots are more easily seen.

• The default is 1200, but you can enter an offset value between 400 and 1600 with MT Frequency Offset.
• In 3D TOF with Magnetization Transfer, the RF pulse is applied 1200 Hz from center frequency and cannot be modified.
• A larger frequency offset is preferred for the 8 ms MT pulse type since its frequency spectrum is wider than the 16 ms pulse, leaving the free water signal unaffected.