Use of the modified three-point Dixon technique in obtaining T1-weighted contrast-enhanced fat-saturated images on an open magnet.

The purpose of this study was to investigate the modified three-point Dixon technique as a method for obtaining fat-saturated T1-weighted sequences before and after intravenous gadolinium administration using an open MR imaging scanner. A preliminary experiment using an oil/gadolinium phantom was performed on a 0.35-T open magnet and an advanced 1.5-T unit. Fat saturation was achieved at 1.5 T using a frequency selective presaturation technique and a modified three-point Dixon technique on the low-field scanner. The modified three-point Dixon sequence was then evaluated in ten patients undergoing MRI examinations of the spine with gadolinium enhancement to determine image characteristics and diagnostic potential. The phantom study demonstrated a homogenous suppression of signal from oil and a good distinction between fat and a gadolinium chelate on the 0.35-T unit comparable to that on the 1.5-T scanner. By applying the modified three-point Dixon technique on the open-magnet, the distinction between fat and gadolinium dimeglumine was rated as very good in 139 and good in 17 axial slices in a total of 156 images. No image was rated as difficult or not possible. Motion artifacts that hampered the reading were detected in the lower cervical spine due to respiratory movement in four (3% of all) images. The modified three-point Dixon technique provides the combination of gadolinium enhancement with fat saturation on an open magnet. Early clinical applications appear promising.