The brachial plexus is a complex network of nerves formed by the anterior rami of the lower four cervical nerves (C5,
C6,
C7,
C8) and first thoracic nerve (T1),
which supplies motor and sensory innervation to the upper limb and pectoral girdle.
Diagnosing brachial plexus pathology was mainly based on medical history,
clinical findings and electromyography (EMG) testing,
while Computed Tomography (CT) and traditional Magnetic Resonance Imaging (MRI) was used to assess tumours.
However,
diagnosing brachial plexus pathology can be really challenging,
often necessitating further evaluation with Magnetic Resonance Neurography (MRN).
MRN is a non-invasive imaging technique for the dedicated assessment of peripheral nerves.
Because of its excellent soft-tissue contrast,
MRN offers anatomical information that is not obtainable with other modalities (fig.
1).
Fig. 1: Coronal thin-section MIP, oblique reconstructions and curved planar reconstructions of a 3D STIR. MRN can optimally demonstrate the nerve roots and the brachial plexus, offering anatomical information that is not obtainable with other imaging modalities. Image dataset acquired at 3 Tesla.
References: Bac Nguyen
Nowadays,
MRN plays a prominent role in the evaluation of the brachial plexus and related pathologies (fig.
2),
thanks to the recent advances in hardware,
software and development of new imaging techniques.
Fig. 2: Coronal thin-section MIP 3D STIR on a patient with neurofibromatosis type 2. MR Neurography can clearly demonstrate the nodular thickening of brachial plexus segments.
References: Bac Nguyen
Nevertheless,
MRN of the brachial plexus remains challenging due to technical limitations,
such as magnetic field inhomogeneities,
motion-sensitive sequences and strong blood and cerebrospinal fluid (CSF) signal (fig.
3).
Fig. 3: Coronal thin-section MIP 2D STIR (A) and coronal thin-section MIP 3D STIR (B). Motion and flow artifacts degrade the image quality (A), while the high signal from the vessels, CSF and lymph nodes can mimic or hide pathology (B). Image dataset acquired at 1.5 Tesla.
References: Bac Nguyen