PURPOSE

To assess the most effective magnetic resonance imaging (MRI) sequence for the visualization of the 9th, 10th, and 11th cranial nerves (glossopharyngeal, vagus, and accessory nerves, respectively) in their intraforaminal/canalicular courses.

MATERIALS AND METHODS

Balanced fast-field echo (b-FFE), 3D-T2W DRIVE, T2W 2D TSE and post-contrast T1W MRI sequences were all applied and we tried to get the best sequence for the exact assessment of the 9th, 10th, and 11th cranial nerves. Six hundred nerves of 100 patients without symptoms of neurovascular compression were examined using the above sequences. Imaging analysis was graded as: a) nerves analyzed by certainty (score of 2), b) nerves analyzed partially (score of 1), and c) nerves not identified (score of 0).

RESULTS

In all three nerves, the best sequence for the visualization of the cisternal and intraforaminal course was b-FFE, with 58%, 73%, 62%, and all together 64.3% success in showing the fascicles of the 9th–11th nerves. This sequence with a very short time of repetition, symmetrical and balanced gradient around the echo time allowed very fast imaging and a high signal to noise ratio. T2W TSE sequence was superior to the DRIVE T2W sequence in assessing the cisternal and intraforaminal part of all three nerves. Post-contrast T1W sequence was probably the worst sequence in showing all three nerves.

CONCLUSION

b-FFE gradient echo MRI sequence with high spatial resolution is the optimal sequence for determining the courses of 9th–11th cranial nerves.

Keywords: magnetic resonance imaging , cranial nerves , skull base