MRI of the Acute Injured Knee

Magnetic Resonance Imaging (MRI) has become a mainstay in the assessment of internal derangement of the knee. MRI prior to surgery increases diagnostic confidence. It also influences clinical practice by identifying alternative diagnoses, e.g., for an osteochondral injury that clinically may mimic meniscal tears, different surgical approaches exist for many cases. This unit presents the standard protocol for imaging injured knees in a clinical setting. The parameters given in this unit are derived from a 1.5 T machine and may need to be altered slightly depending on the main magnetic field strength and the equipment manufacturer.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145407/1/cpmia2301.pd

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 1.5T 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 promisin