Medical Policy



Subject: Magnetic Resonance Neurography
Document #: RAD.00044 Current Effective Date:    06/28/2017
Status: Reviewed Last Review Date:    05/04/2017

Description/Scope

This document addresses the use of magnetic resonance neurography, also known as magnetic resonance neurogram.

Position Statement

Investigational and Not Medically Necessary:

Magnetic resonance neurography is considered investigational and not medically necessary.

Rationale

Magnetic resonance neurography has been proposed for the diagnosis of peripheral nerve disorders. Peripheral nerve disease can often be diagnosed using a combination of clinical history and neurological exam. In some cases, electromyography (EMG), nerve conduction studies (NCS) and nerve biopsy may be used. Magnetic resonance neurography of the spinal and peripheral nerves has been proposed as an additional diagnostic tool.

Filler and colleagues (2005) published a non-randomized controlled trial which consisted of 239 consecutive participants with sciatica of unknown etiology for which standard diagnosis and treatment failed. These individuals, who had similar symptoms, underwent conventional magnetic resonance imaging (MRI) and magnetic resonance neurography followed by MR-guided marcaine injection into the piriformis muscle. The diagnostic efficacy revealed that piriformis muscle asymmetry and sciatic nerve hyperintensity at the sciatic notch exhibited a 93% specificity and 64% sensitivity in distinguishing individuals with from those without piriformis syndrome. It must be noted that this is a single study regarding a single anatomic area and diagnostic issue, and thus is not generalizable to other uses for magnetic resonance neurography.

Du and colleagues (2010) reported on the use of magnetic resonance neurography in the management of spinal and peripheral nerve disorders. They retrospectively reviewed the charts of 191 individuals who had undergone magnetic resonance neurography. Ninety-one of those individuals also underwent comparative EMG/NCS. When the magnetic resonance neurography was compared to EMG/NCS, 29 individuals received the same diagnostic information, 41 individuals received additional diagnostic information, 15 individuals received less diagnostic information and 6 individuals received a different diagnosis altogether. The median timeframe of imaging was 12 months following the onset of symptoms. The authors suggest several potential uses for magnetic resonance neurography. They also noted that magnetic resonance neurography is less useful if done greater than 1 year after the onset of symptoms and that magnetic resonance neurography is limited due to its ability to only image a selected region of the nerve pathway.

In a retrospective review by Fisher and colleagues (2016), the authors reviewed 121 magnetic resonance neurography exams that were done on individuals with suspected but unknown brachial plexopathy. After the interpretation of the magnetic resonance neurography exams, the impact of the magnetic resonance neurography on the pre-imaging clinical diagnosis and treatment plan was classified as concordant, mild change or substantial change. Mild change was defined as the difference in severity of disease unlikely to affect treatment planning. Substantial change was defined as a large deviation from expected severity of disease, a separate disease etiology, or actionable and previously unknown incidental findings. A total of 47 electrodiagnostic exams were performed prior to the magnetic resonance neurography and 31 of these electrodiagnostic exams were concordant with the magnetic resonance neurography findings, and 16 electrodiagnostic exams showed a discordance in the diagnosis between electromyography and magnetic resonance neurography. After magnetic resonance neurography, there was a change in pre-imaging clinical impression for 91 of the participants (mild change in diagnosis in 57 participants and substantial change in 34 participants). A total of 19 participants proceeded to therapies that would not have been ordered if not for the magnetic resonance neurography results. Limitations to this study include the retrospective nature and the subjectivity in categorizing a mild or substantial change in diagnosis. There were no future outcomes data for the participants and for those who had electrodiagnostic exams prior to magnetic resonance neurography exams, the results were available prior to imaging almost 55% of the time which may have led to an influence of interpretation of the magnetic resonance neurography.

At this time there is inadequate data regarding the diagnostic performance of magnetic resonance neurography, in terms of defining the normal range of morphologies, the sensitivity and specificity of identification of abnormalities in comparison to other diagnostic tests, and the impact on the management of the individual. Much of the current literature is limited to retrospective reviews (Chhabra, 2012; Keen, 2012; Lee, 2012) and studies with small participant numbers (Wolf, 2014).

Background/Overview

Conventional evaluation of peripheral nerves typically relies on an individual's clinical history, neurological examination and electrodiagnostic tests.

Magnetic resonance neurography is an imaging procedure involving the use of a standard MRI machine augmented with special software and hardware upgrades. The development of magnetic resonance neurography enables direct high-resolution longitudinal and cross-sectional images of peripheral nerves such that the morphology of the nerve can be visualized. These upgrades allow the device to emit special magnetic sequences, which are detected by specialized custom-built phased-array imaging surface coils.

Magnetic resonance neurography has been proposed as a new method by which nerves in the body can be imaged in a manner not possible with other imaging methodologies.

Definitions

Magnetic resonance: The absorption of specific frequencies of radio and microwave radiation by atoms placed in a magnetic field, revealing molecular structure.

Magnetic resonance neurography: A means of optimizing an MRI scan for sensitivity to special biophysical properties of nerves.

Coding

The following codes for treatments and procedures applicable to this document are included below for informational purposes. Inclusion or exclusion of a procedure, diagnosis or device code(s) does not constitute or imply member coverage or provider reimbursement policy. Please refer to the member's contract benefits in effect at the time of service to determine coverage or non-coverage of these services as it applies to an individual member.

When services are Investigational and Not Medically Necessary:
When the code describes a procedure indicated in the Position Statement section as investigational and not medically necessary.

CPT  
76498 Unlisted magnetic resonance procedure (eg, diagnostic, interventional) [when specified as magnetic resonance neurography]
   
ICD-10 Diagnosis  
  All diagnoses
   
References

Peer Reviewed Publications:

  1. Chhabra A, Chalian M, Soldatos T, et al. 3-T high-resolution MR neurography of sciatic neuropathy. AJR Am J Roentgenol. 2012; 198(4):W357-364.
  2. Cudlip SA, Howe FA, Griffiths JR, Bell BA. Magnetic resonance neurography of peripheral nerve following experimental crush injury, and correlation with functional deficit. J Neurosurg. 2002; 96(4):755-759.
  3. Du R, Auguste KI, Chin CT, et al. Magnetic resonance neurography for the evaluation of peripheral nerve, brachial plexus, and nerve root disorders. J Neurosurg. 2010; 112(2):362-371.
  4. Filler AG, Haynes J, Jordan SE, et al. Sciatica of nondisc origin and piriformis syndrome: diagnosis by magnetic resonance neurography and interventional magnetic resonance imaging with outcome study of resulting treatment. J Neurosurg Spine. 2005; 2(2):99-115.
  5. Fisher S, Wadhwa V, Manthuruthil C, et al. Clinical impact of magnetic resonance neurography in patients with brachial plexus neuropathies. Br J Radiol. 2016; 89(1067):20160503.
  6. Keen NN, Chin CT, Engstrom JW, et al. Diagnosing ulnar neuropathy at the elbow using magnetic resonance neurography. Skeletal Radiol. 2012; 41(4):401-407.
  7. Lee PP, Chalian M, Bizzell C, et al. Magnetic resonance neurography of common peroneal (fibular) neuropathy. J Comput Assist Tomogr. 2012; 36(4):455-461.
  8. Wolf M, Bäumer P, Pedro M, et al. Sciatic nerve injury related to hip replacement surgery: imaging detection by MR neurography despite susceptibility artifacts. PLoS One. 2014; 9(2):e89154.
Index

Magnetic Resonance Neurogram
Magnetic Resonance Neurography
MRN

Document History
Status Date Action
Reviewed 05/04/2017 Medical Policy & Technology Assessment Committee (MPTAC) review. Updated Rationale and References sections.
Reviewed 05/05/2016 MPTAC review. Updated Description/Scope, Rationale, and Background sections. Removed ICD-9 codes from Coding section.
Reviewed 05/07/2015 MPTAC review. Updated Description/Scope.
Reviewed 05/15/2014 MPTAC review. Updated Rationale and References.
Reviewed 05/09/2013 MPTAC review. Updated Rationale and References.
Reviewed 05/10/2012 MPTAC review. No change to Position Statement.
Reviewed 05/19/2011 MPTAC review. Updated Rationale and References.
Reviewed 05/13/2010 MPTAC review. No change to Position Statement.
Reviewed 05/21/2009 MPTAC review. No change to Position Statement.
Reviewed 05/15/2008 MPTAC review. No change to Position Statement.
  02/21/2008 The phrase "investigational/not medically necessary" was clarified to read "investigational and not medically necessary." This change was approved at the November 29, 2007 MPTAC meeting.
Reviewed 05/17/2007 MPTAC review. No change to Position Statement. Updated Rationale, Background and Index sections.
Reviewed 09/14/2006 MPTAC review. References updated; no change to Position.
Revised 09/22/2005 MPTAC review. Revision based on Pre-Merger Anthem and Pre-Merger WellPoint Harmonization.
Pre-Merger Organizations

Last Review Date

Document Number

Title

 

Anthem, Inc.

 

None  
WellPoint Health Networks, Inc.

12/02/2004

4.01.22

Magnetic Resonance Neurography