Magnetic resonance imaging of cranial nerves at 7 Tesla.

PURPOSE: The aim of this study was to demonstrate the feasibility of cranial nerve (CN II-XII) imaging with 7 Tesla magnetic resonance imaging (MRI).

METHODS

In this study four sequences were evaluated in three healthy volunteers using magnetization preparation rapid gradient echo (MPRAGE), constructive interference in steady state (CISS), true fast imaging with steady state precession (TrueFISP) and proton density (PD) T2-weighted turbo spin echo (TSE) sequences.

RESULTS

It was found that MPRAGE did not always provide sufficient contrast to delineate in particular small CNs but displayed an overall good identification rate. The T2 sequence was not able to adequately differentiate the small CNs but showed a very good contrast between nerves and cerebrospinal fluid (CSF). As at lower magnetic fields steady state sequences displayed a high identification rate of all CNs in the axial plane but CISS suffered from susceptibility and pulsation artifacts, furthermore it was limited as no parallel imaging could be performed. The TrueFISP technique was reliable in identifying most CNs although suffering from banding artifacts.

CONCLUSIONS

The TrueFISP sequence showed superior spatial resolution and contrast in comparison to the other sequences for imaging of CNs at 7 T.