Advances in cranial nerve imaging: emerging MRI techniques

This paper presents an update on cranial nerve imaging with new imaging techniques applied on a nerve by nerve based literature research. Imaging small structures in the human body such as the cranial nerves often poses a challenge in MRI imaging. It requires investment in spatial resolution with acceptable MRI scantimes. The radiologist should also be aware of the anatomical course of all 12 cranial nerves, and know which type of sequence is best used to visualize each part of the cranial nerve from the brainstem to the end-organ. This paper does not cover the complex radiological anatomy of the cranial nerves, this is already available in many other manuscripts. Nor will this paper cover all the possible pathologies that can affect the cranial nerves, this is also described in many other manuscripts. Newer imaging techniques, such as contrast-enhanced black-blood T1-weighted imaging, are increasingly used to improve detection of cranial nerve inflammation. While diffusion tensor imaging is currently used primarily to evaluate the integrity of the cisternal nerve segments, contrast-enhanced black-blood T1-weighted imaging can provide additional information about the cisternal, foraminal, cavernous, and extracranial portions of the cranial nerves. MR neurography techniques have recently been developed with better demonstration of the extracranial course of the cranial nerves. Detection of inflammatory or demyelinating nerve disease will mostly benefit from using these new imaging techniques. Some practical tips to optimize cranial nerve MRI scanning are provided.