MR imaging of the neural foramina of the cervical spine. Comparison of 3D-DESS and 3D-FISP sequences

Purpose: To assess whether a single three-dimensional double-echo steady state (3D-DESS) sequence can produce equivalent results when compared to a 3D free induction with steady precession (3D-FISP) sequence for the evaluation of the neural foraminal diameter and structures.Material and Methods: Five phantoms were imaged on CT with 3-mm axial slices followed by reformatted axial 3D-DESS and 3D-FISP sequences. In addition, 3D-DESS and 3D-FISP sequences of 20 healthy subjects were compared with regard to image quality, differentiation between vertebrae and discs, differentiation between discs and neural foramina, and differentiation between vertebrae and neural foramina.Results: Compared with CT, 3D-DESS and 3D-FISP sequences consistently underestimated the diameters of the neural foramina. The mean difference values for the 3D-DESS was 12.8%, compared to 9.5% for the 3D-FISP sequence. Concerning the in vivo studies, the 3D-DESS sequence was superior but not statistical significant to the 3D-FISP sequence with regard to image quality, differentiation between vertebrae and discs, differentiation between discs and neural formina, and identification of the nerve roots.Conclusion: The 3D-DESS sequence is moderately accurate in the evaluation of the neural foraminal size. Compared to the 3D-FISP sequence, the 3D-DESS sequence is compatible concerning the image quality, differentiation between the cervical vertebrae and discs, and between the discs and neural foramina.