Visualization of the 12th Cranial Nerve with MRI: Value of Balanced Fast-Field Echo and 3D-Drive Sequences Among the T2 TSE Post- Contrast T1 Sequences

Background/Objective: Our aim was to optimize the most effective MR imaging sequence for visualization of the 12th cranial nerve (hypoglossal nerve) through its cisternal course. Patients and Methods: We applied balanced fast-field echo (B-FFE), 3D-T2 weighted Driven Equilibrium RF Reset Pulse (DRIVE), T2 weighted 2D TSE and post-contrast T1 weighted sequences and tried to find out the best sequence for the perfect visualization of the 12th cranial nerve. One-hundred patients without any hypoglossal nerve paralysis were examined via these sequences. Imaging analysis was graded as follows: certain visualization of nerves (score 2), partially visualized nerves (score 1), non-visualized nerves (score 0). Results: The hypoglossal nerve was visualized exactly in only eight cases and partially depicted in only six cases with the post-contrast T1 series. In B-FFE sequence; 56% of the nerves were properly seen and 8% of the nerves were partially identified, using T2 weighted DRIVE sequences; 30% of the nerves were clearly visualized, the nerves were partially depicted in 15 patients. Regarding the T2 weighted TSE sequence, 15% of the nerves were certainly depicted and in seven patients the nerves were partially depicted. Conclusion: The most diagnostic sequence for the exact visualization of the cisternal course of hypoglossal nerve is B-FFE revealing a 64% visualization rate for the cisternal parts (112 exactly, 16 partially). T2W DRIVE sequence is shown to be more diagnostic than the T2W TSE for visualization of the cisternal part of the hypoglossal nerve.