rUniversity of Iowa Hospital, Iowa City, Iowa, Primary care physician. sUniversity of Colorado Denver, Denver, Colorado. tSpecialty Chair, Atlanta VA Health Care System and Emory University, Atlanta, Georgia. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. Reprint requests to: publications@acr.org Cranial Neuropathy Special Imaging Considerations MRI is the standard modality for imaging the CNs. Imaging with 3.0T is preferred over 1.5T imaging because of superior signal-to-noise ratios, gradient strength, and spatial resolution, although diagnostic information can be obtained with 1.5T imaging when 3.0T imaging is not available or precluded [5]. A phased-array head coil suffices for most examinations; specialized surface coils may supplement examinations of peripherally located nerves [5,19,20]. Fundamental techniques include thin-cut T1-weighted, T2-weighted, and contrast-enhanced T1-weighted sequences. The unenhanced T1-weighted sequence remains an excellent baseline technique for anatomic evaluation because of the natural contrast provided by fat in the neck and skull base. Diffusion-weighted imaging (DWI) is useful to assess for acute infarctions, cellular tumors, or specific lesions that may affect CN function, such as epidermoids or cholesteatomas. Thin section nonecho planar DWI with decreased susceptibility artifact compared with echo planar DWI allows for increased sensitivity in detection of small cholesteatomas. The use of intravenous (IV) contrast is imperative for the evaluation of cranial neuropathy with MRI. Neck CT also requires the use of IV contrast when evaluating for lesions in the neck causing cranial neuropathy.
Cranial Neuropathy. rUniversity of Iowa Hospital, Iowa City, Iowa, Primary care physician. sUniversity of Colorado Denver, Denver, Colorado. tSpecialty Chair, Atlanta VA Health Care System and Emory University, Atlanta, Georgia. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. Reprint requests to: publications@acr.org Cranial Neuropathy Special Imaging Considerations MRI is the standard modality for imaging the CNs. Imaging with 3.0T is preferred over 1.5T imaging because of superior signal-to-noise ratios, gradient strength, and spatial resolution, although diagnostic information can be obtained with 1.5T imaging when 3.0T imaging is not available or precluded [5]. A phased-array head coil suffices for most examinations; specialized surface coils may supplement examinations of peripherally located nerves [5,19,20]. Fundamental techniques include thin-cut T1-weighted, T2-weighted, and contrast-enhanced T1-weighted sequences. The unenhanced T1-weighted sequence remains an excellent baseline technique for anatomic evaluation because of the natural contrast provided by fat in the neck and skull base. Diffusion-weighted imaging (DWI) is useful to assess for acute infarctions, cellular tumors, or specific lesions that may affect CN function, such as epidermoids or cholesteatomas. Thin section nonecho planar DWI with decreased susceptibility artifact compared with echo planar DWI allows for increased sensitivity in detection of small cholesteatomas. The use of intravenous (IV) contrast is imperative for the evaluation of cranial neuropathy with MRI. Neck CT also requires the use of IV contrast when evaluating for lesions in the neck causing cranial neuropathy.