1.
Patient placement.
Patient in supine decubitus using the brachial plexus combination coils.
It is very important to tilt the neck slighty in order to improve the plexus signal.
Fig. 9
2.
Sequences.
2.1 Propeller : a radial sampling method using rotation blades composed of multiple phase-encoded lines. This technique allows to reduce the movement artifacts that are produced mainly by the patient's breathing.
We will perform the sequence in the sagital plane oriented with the medulla and T2 weigthed image, acomplishing the dixon sequence oriented in the coronal plane by adjusting the number of slices to the study area.
FOV(cm) |
Slice thickness(mm) |
Pixel Size |
TR(ms) |
TE(ms) |
ETL |
FA |
Bandwith |
Adquisition time |
24 |
3.0 x 1 |
0.6 x 0.9 |
>2000 |
100-110 |
16 |
160 |
31.25 |
1'51'' |
Fig. 7
2.2 DIXON : Dixon method combine 3 echoes acquired at the different TE'S to create water-only and fat-only images,
being relatively insensitive to B0 and B1 inhomogeneities.
In our protocol we perform the dixon sequence in the coronal plane,
obtaining a good morphological image of the brachial plexus and being able to perform the sagital sequences with the correct angle.
FOV(cm) |
Slice thickness(mm) |
Pixel Size |
TR(ms) |
TE(ms) |
ETL |
FA |
Bandwith |
Adquisition time |
26 |
4.0 x 0 |
1.0 x 1.2 |
>4000 |
100-110 |
18 |
160 |
62.50 |
3'11'' |
Fig. 3
2.3 Difussion weigthed images : is a form of MR imaging based upon measuring the random Brownian miton of water molecules withing a voxel of tissue.
In general simplified terms,
highly cellular tissues or those with celullar swelling exhibit lower difussion coefficients.
Difussion is particularly useful in tumor characterization.
We perform the DWI in axial plane using the coronal DIXON to include all the plexus anatomy.
Then we reconstruct the image in coronal plane.
FOV |
Slice thickness(mm) |
Pixel size |
TR(ms) |
TE(ms) |
Inversion time(ms) |
b-Value |
DWI direction |
Asset |
Adquisition time |
40 |
4.0 x 0 |
4.2 x 4.2 |
>10000 |
62 |
180 |
700 (1) |
ALL |
YES |
5'54'' |
Fig. 4
2.4 Cube STIR : These are closely related fast (Turbo) spin echo techniques with special modifications optimizing them for isotropic 3D imaging. The STIR provides an IR pulse for Fat supression.
We acquire this sequence in coronal orientation.
It is important to inject contrast 5 minutes before the adquisition in order to supress the vessel's signal.
FOV(cm) |
Slice thickness(mm) |
Pixel size |
TR(ms) |
TE(ms) |
ETL |
Inversion time(ms) |
Bandwith |
Adquisition time |
36.0 |
1.4 |
1.4x1.4 |
5500 |
90 |
100 |
160 |
62.50 |
4'58'' |
Fig. 8
3.
Clinical cases.
-Preganglionic involvement of the right C7 root,
with extension of the inflamatory afffectation to the middle trunk,
divisions and lateral cords ( musculocutaneous and median nerves) and posterior (radial nerve).
Fig. 10
-23 mm nodule compatible with nerve tumor of the peripheral sheath of the posterior fascicle of the left brachial plexus.
Fig. 11
Fig. 12
-Slight thickening and hyper signaling of the right C5 root,
at the height of the scalenes where it forms the upper trunk with the C6 root and lesser measure in a more proximal situation suggesting radioculopaty without evidence of preganglionic lesion.
Fig. 13
-Thickening and hyper signaling of the lower trunk,
the medial cord and the beginning of terminal branches,
especially the ulnar nerve,
which could be in the context of the chronic demyelinating polyneuropathy,
being essential the correlation with clinical data.
Fig. 14