← Back to Browse
Ask AleraHome
MRI
MusculoskeletalDemonstration data

MR Neurography - Brachial Plexus

MR neurography uses nerve-selective, high-resolution and fluid-sensitive sequences with fat and vascular suppression to display the brachial plexus from the cervical roots to the terminal branches. It characterises traumatic, neoplastic, inflammatory and compressive plexopathies and, together with muscle denervation signal, localises and grades nerve injury.

Indications

  • Traumatic brachial plexopathy and suspected nerve root avulsion
  • Peripheral nerve sheath tumours (schwannoma, neurofibroma) and plexiform neurofibromatosis
  • Metastatic or direct tumour infiltration (e.g. Pancoast tumour, breast cancer)
  • Thoracic outlet syndrome with neurogenic symptoms
  • Radiation-induced versus recurrent tumour plexopathy
  • Inflammatory neuropathies (e.g. Parsonage-Turner syndrome) and post-surgical assessment

Contraindications & Cautions

  • Non-conditional pacemakers, ICDs, neurostimulators and ferromagnetic implants
  • Cochlear implants and unstable metallic intra-ocular foreign bodies
  • Severe claustrophobia without sedation
  • Gadolinium caution with eGFR <30 mL/min/1.73 m2 when contrast is needed for a mass
  • Pregnancy: unenhanced neurography can be performed; avoid gadolinium unless essential

Patient Preparation

  • MRI safety screening and removal of ferromagnetic objects
  • Position supine with arms by the side; consider arm abduction for suspected thoracic outlet syndrome
  • Explain the long acquisition times of 3D sequences and the need to remain still
  • Intravenous cannula when a tumour or inflammatory cause is suspected
  • Correlate with electrodiagnostic (EMG/NCS) findings to focus the examination

Technique & Parameters

  • Coronal and sagittal-oblique T1 for anatomy and fat planes around the plexus
  • Fat-suppressed T2 or STIR to highlight increased nerve signal and denervation oedema
  • 3D isotropic nerve-selective sequences (e.g. 3D STIR SPACE, DW reversed-FISP/PSIF) with vascular suppression for maximum-intensity nerve reconstructions
  • High-resolution axial imaging through the interscalene, costoclavicular and retropectoral regions
  • Post-gadolinium fat-saturated T1 when a mass or inflammatory/neoplastic infiltration is suspected
  • 1.5T or 3T with surface/phased-array coils covering the neck, plexus and axilla

Systematic Review

  • Trace each level: roots (C5-T1), trunks, divisions, cords (lateral, posterior, medial) and terminal branches
  • Assess nerve calibre, signal intensity, fascicular pattern and continuity
  • Look for pseudomeningoceles and absent/displaced roots indicating avulsion
  • Evaluate for a mass, its relationship to the nerve and enhancement pattern
  • Assess the interscalene triangle, costoclavicular space and retropectoral tunnel for compression
  • Review shoulder-girdle muscles for denervation oedema (subacute) or fatty atrophy (chronic)

Key Findings & Significance

  • Root avulsion: pseudomeningocele, empty nerve root sleeve and displaced/absent nerve root
  • Nerve sheath tumour: fusiform T2-hyperintense mass along the nerve with a target sign and split-fat sign, enhancing after contrast
  • Tumour infiltration: nodular or diffuse T2 signal and enhancement encasing the plexus (Pancoast, breast metastasis)
  • Radiation plexopathy: diffuse T2 signal without a focal mass, often with tissue fibrosis
  • Parsonage-Turner: hyperintense enlarged nerve segments with corresponding muscle denervation oedema
  • Thoracic outlet syndrome: nerve displacement/compression at the costoclavicular space, accentuated on abduction

Differential Considerations

  • Focal plexus mass: schwannoma, neurofibroma, malignant peripheral nerve sheath tumour, metastasis, lymphoma
  • Diffuse plexus signal/enhancement: radiation plexopathy, inflammatory neuritis, metastatic infiltration
  • Post-traumatic: root avulsion (pre-ganglionic) versus post-ganglionic rupture/stretch injury
  • Denervation muscle oedema: nerve injury, neuritis, or non-specific (recent activity)
  • Thoracic outlet compression: neurogenic, arterial or venous subtypes

Pearls & Pitfalls

  • Distinguishing pre-ganglionic (avulsion, with pseudomeningocele) from post-ganglionic injury is critical for surgical planning
  • The target sign and split-fat sign help identify a benign peripheral nerve sheath tumour
  • Rapid growth, ill-defined margins, heterogeneity and perilesional oedema raise concern for malignant transformation
  • Muscle denervation signal helps localise the level and chronicity of nerve injury
  • Provocative arm-abduction imaging increases sensitivity for neurogenic thoracic outlet syndrome

Structured Report

  • State field strength, nerve-selective sequences and whether contrast was given
  • Report the level and nature of the abnormality (roots to terminal branches)
  • Distinguish pre- from post-ganglionic injury in trauma and describe pseudomeningoceles
  • Characterise any mass and its relationship to the nerve and adjacent vessels
  • Describe muscle denervation and provide an impression correlated with EMG/NCS

References

  • Chhabra A, et al. MR neurography: technique and clinical applications. Radiographics
  • Wade RG, et al. Magnetic resonance imaging for detecting root avulsions in traumatic brachial plexus injury
  • ISMRM MSK/Peripheral Nerve Study Group recommendations on MR neurography
  • Van Es HW, et al. MRI of the brachial plexus. European Radiology

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.