With the higher SNR of 3 Tesla and software developments, 3D spin echo–type sequences with good contrast to noise ratio become possible in a reasonable scan time of 5 to 6 minutes. These MR sequences include sampling perfection with application-optimized contrasts using different flip angle evolutions, CUBE, and volume isotropic turbo spin-echo acquisition. They are somewhat insensitive to magnetization transfer–related cross talk among slices, allow thin-slice multiplanar reconstructions from isotropic voxels, and can produce a variety of contrasts (eg, proton density and T2). They may be used with fat-suppression techniques, such as SPAIR and STIR .
Rodegerdts and associates8 described their experience with 3D sequences of whole-spine MRI at 3 Tesla MRI compared with 1.5 Tesla MRI. They concluded that 3D imaging has a higher SNR on 3 Tesla than on 1.5 Tesla and that better signal can be used to increase the spatial resolution. Of note, the interpatient variability at 3 Tesla was greater than at 1.5 Tesla because of the B1 inhomogeneity related to dielectric effects.
