Low Flip Angle Gradient Echo MRI of the Cervical Spine at 0.3 Tesla

Abstract

Using the gradient echo technique in MR imaging of the cervical spine, the effect on contrast of changing flip angle and repetition time was evaluated in five volunteers. A 0.3 T Fonar s-3000 M scanner and solenoid surface coils were used in the study. Short TR/TE (300/12 msec) sequences with a flip angle of 10° provided the best contrast. CSF and discs had a high signal while cord, epidural space and vertebrae had a low signal. The image thus had the same myelographic appearance as on long TR/TE spin echo (SE) sequences, but could be obtained using a shorter acquisition time. Furthermore, it was possible to separate gray and white matter and no artifacts were caused by CSF pulsation. The limitation of the technique is the rather low signal/noise, which is, however, well compensated by the superior contrast. Ten patients with degenerative disease were studied with this technique and short TR/TE (300/16 msec) SE sequences. The low flip angle sequences were superior in visualizing narrowing of canal and compression of cord and it was in general easier to discriminate between bone and disc herniation. In five patients with lesions in the cord visualized on long TR/TE (2000/60 msec) SE sequences, the lesions were also visualized using the low flip angle gradient echo technique. In conclusion: 10° flip angle gradient echo (TR/TE 300/12 msec) sequences provides images with: 1. myelographic effect with separation of cord, CSF, epidural space, disc and bone, 2. separation of gray and white matter in the cord, 3. demonstration of lesions in the cord.