Norm of Magnetic Resonance Neurography (MRN, Neurography)
Description of normal nerve structure.
Usage of Magnetic Resonance Neurography (MRN, Neurography)
Helps diagnose and evaluate peripheral nerve tumors, carpal tunnel syndrome, ulnar nerve compression, thoracic outlet syndrome, brachial plexus injuries (including birth injuries), sciatica with no convincing spinal cause, any suspected nerve impingement, accidental injury to peripheral nerves, postirradiation neuritis, chronic nerve compression, and pain syndromes when an anatomic lesion is suspected. In the evaluation of clients with spinal problems, it can also be used as a follow-up or adjunct test to MRI, CT, and myelogram when there are ambiguous test results or if the client has clinical symptoms that are not confined to a single dermatome. MRN may also be useful in surgical planning to localize and determine the resectability of tumors through accurate depiction of the relation of the tumor to the nerve fascicles or presence of nerve laceration.
Description of Magnetic Resonance Neurography (MRN, Neurography)
MRN provides longitudinal and cross-sectional fascicular images of nerves. It is a noninvasive imaging technique that uses a magnetic resonance imaging (MRI) scanner that has been modified with a spin-echo pulse sequence combined with fat suppression and diffusion weighting to generate neurographic images. MRN images show the nerves as the most prominent feature, providing detail of the internal fascicular structure. The cross-sectional images can be viewed individually or reconstructed to provide fully isolated nerves and nerve structure (longitudinal views).
Professional Considerations of Magnetic Resonance Neurography (MRN, Neurography)
Consent form IS required.
- See Preparation, Magnetic resonance imaging.
- See Procedure, Magnetic resonance imaging.
- Contrast medium is not used in this test.
- See Postprocedure Care, Magnetic resonance imaging.
Client and Family Teaching
- See Client and Family Teaching, Magnetic resonance imaging.
- There is no contrast agent used and there are no injections.
- The test takes about 30–40 minutes.
Factors That Affect Results
- See Factors That Affect Results, Magnetic resonance imaging.
- Variable sensitivity occurs in imaging very small nerves. Decreased sensitivity is associated with imaging small nerves that traverse multiple anatomic planes, such as those in the pelvis (that is, the ilioinguinal nerve).
- It is important that clinical evaluation correlate with abnormal findings of MRN. It has been reported that up to 60% of the population with no pain have been found to have a herniated disk, bone spurs, or narrowing of spinal canals. In a symptomatic client, these “commonly occurring” abnormalities may be inaccurately diagnosed as the cause of the symptoms when in actuality the pathologic condition is located at a more distal nerve site.
- At this time, MRN cannot be accomplished by means of the “open” MRI machines. The magnet-field gradient required for MRN imaging cannot be maintained with the open MRI equipment.