Segmented Insert Gradient Coil for Bilateral Knee Imaging

Sung M. Moon¹, K. Craig Goodrich¹, J Rock Hadley¹, Dennis L. Parker¹

MRI of the knee can benefit from high spatial resolution and short echo times for both proton and sodium-23 imaging of cartilage. With higher gradient strength and slew rate, the insert gradient coils can attain shorter echo times and higher spatial and temporal resolution than the body gradients. Prior flat gradient system designs have relatively smaller HGVs, which are not quite wide enough for bilateral knee imaging. To image both knees simultaneously, we have developed a segmented two-region insert gradient system which has two wide HGVs, one for each knee, along the x-axis. This was achieved by adding an extra vertical winding in the middle of the x-gradient to create high gradient strength, and by using superelliptical geometry, which enlarges the HGV dramatically by spreading wire patterns around both knees.