Short TR, variable flip angle, gradient echo scans of the cervical spine: comparison of 2DFT and 3DFT techniques

A prospective study of 16 patients was performed to compare quantitatively a contiguous single slice 2DFT version with a 3DFT version of a short TR, variable flip angle, gradient echo (GRASS) pulse sequence. The 3DFT GRASS scans had higher signal-to-noise ratios (SNR) of cord and CSF compared to the single slice 2DFT GRASS scans. The 3DFT GRASS scans, however, had lower CSF-cord and CSF-disc contrast than the single slice 2DFT version. The 3DFT GRASS sequence demonstrated comparable contrast only on the end slices of an imaging volume suggesting influence of an entry phenomenon. The lower CSF-cord and CSF-disc contrast of the 3DFT GRASS technique diminished its usefulness in the diagnosis of cervical disc disease compared to the single slice 2DFT GRASS technique. Two different slice thicknesses (3 mm and 5 mm) were investigated with the 2DFT GRASS technique and found to be comparable although the 3 mm scans had sharper disc and dural margins because of less partial volume artifact.