How to Get Brachial Plexus MRI Approved
To get a brachial plexus MRI approved, you must order it using the correct CPT code based on the clinical indication: use MRI chest for suspected Pancoast tumor, MRI orbit/face/neck for head and neck cancers extending to the brachial plexus, or MRI upper extremity for shoulder girdle/axillary tumors or nonspecific brachial plexopathy symptoms. 1
Understanding the CPT Coding Challenge
The fundamental issue is that no specific CPT code exists for brachial plexus MRI, despite having ICD-10 codes for brachial plexus disorders. 1 The American College of Radiology's Economics Committee on Coding & Nomenclature established that the appropriate CPT code depends entirely on your clinical indication. 1
Selecting the Correct CPT Code
For Suspected Malignancy:
- MRI chest (focusing on brachial plexus): Use for apical lung cancers (Pancoast tumors) 1
- MRI orbit, face and neck: Use for head and neck cancers extending to thyroid level, including brachial plexus involvement 1
For Nontraumatic Plexopathy Without Malignancy:
- MRI upper extremity: Use for shoulder girdle/axillary tumors or nonspecific brachial plexopathy symptoms requiring nerve imaging 1
Critical Documentation Requirements
Your authorization request must emphasize that dedicated brachial plexus imaging differs fundamentally from routine neck, chest, spine, or upper extremity MRI protocols. 1, 2 Standard protocols are inadequate and should not be considered alternatives to dedicated plexus imaging. 1
Specify These Technical Requirements:
- Orthogonal views through the oblique planes of the plexus 1
- T1-weighted sequences 1
- T2-weighted sequences 1
- Fat-saturated T2-weighted or STIR sequences 1, 2
- Fat-saturated T1-weighted postcontrast sequences (when contrast indicated) 1, 2
Clinical Justification Strategy
Document Plexopathy Symptoms (Not Radiculopathy):
- Neuropathic pain in multiple peripheral nerve distributions (not dermatomal) 1
- Weakness, sensory loss, and flaccid loss of reflexes in C5-T1 distribution 1
- Dysesthesia, burning, or electric sensations in multiple nerve territories 1
Critical distinction: If symptoms follow a single dermatomal distribution, this suggests radiculopathy rather than plexopathy, and different imaging is appropriate. 1
State That MRI Is the Gold Standard:
- MRI is the mainstay of plexus imaging with superior soft-tissue contrast and spatial resolution 1, 2
- MRI provides superior definition of intraneural anatomy and localizes pathologic lesions when electrodiagnostic findings are nonspecific 1
- MRI is the most accurate method to determine whether masses are intrinsic or extrinsic to plexus nerves 1
Differential Diagnosis to Include
List potential etiologies that MRI can identify:
- Intrinsic nerve sheath tumors (schwannomas, neurofibromas) 1
- Malignant peripheral nerve sheath tumors (14% of neurogenic tumors) 1
- Inflammatory conditions (Parsonage-Turner syndrome/brachial neuritis) 2
- Infectious, autoimmune, or idiopathic neuropathies 1
- Extrinsic compression from adjacent structures 1
- Chronic inflammatory demyelinating polyneuropathy 1
Common Pitfalls to Avoid
Do Not Accept These Substitutions:
- Routine neck MRI - inadequate for plexus evaluation 1, 2
- Routine chest MRI - inadequate for plexus evaluation 1, 2
- Cervical spine MRI - inadequate for plexus evaluation 1, 2
- Standard upper extremity MRI - inadequate without dedicated plexus protocol 1, 2
Emphasize Protocol Specificity:
State explicitly that the study requires MR neurography techniques with high-resolution T2-weighted sequences of peripheral nerves, which are routinely performed in dedicated brachial plexus protocols but not in standard regional imaging. 1
When Contrast Is Needed
Order MRI without and with IV contrast when evaluating for:
- Suspected intrinsic versus extrinsic nerve masses 1, 2
- Known or suspected malignancy 2
- Inflammatory or infectious etiologies 2
Alternative Imaging If MRI Denied
If MRI is contraindicated or denied:
- CT neck with IV contrast offers the next highest level of anatomic visualization 1, 2
- FDG-PET/CT is appropriate only for known malignancy or post-treatment syndrome 1, 2