Merits of Advanced MRI Techniques (STIR-MIP, Diffusion with Body Suppression, and MR Myelography) over Conventional MRI Techniques in Evaluation of Traumatic Brachial Plexopathy

Purpose: To determine the advantages of advanced sequences such as short tau inversion recovery with maximum intensity projection (STIR-MIP), diffusion with body suppression, and magnetic resonance (MR) myelography in the evaluation of traumatic brachial plexopathy and emphasizing the pattern of nerve injuries after trauma with review of the literature.

Methods and Materials: This was a prospective study of 243 clinically suspected cases of traumatic brachial plexopathy with subjects aged infant to 80 years from 2009 to the present. Using a 1.5-T magnet and16-channel Torso array coil and 4-channel shoulder coil, advanced sequences like diffusion-weighted imaging with diffusion-weighted imaging-whole-body imaging with background body signal suppression (DWI-DWIBS), STIR-MIP coronal postprocessing, and MR myelography (T2 DRIVE) and conventional sequences (T1-weighted imaging, T2-weighted imaging, and STIR) were performed ([Fig. 1]).

Results: The time taken for the advanced imaging techniques is 75% less than that for conventional sequences. Wide field of view STIR MIP with cine aids in comparing with the normal side.

Of 243 clinically suspected cases of traumatic brachial plexopathy, 216 were positive and 27 were negative. Of the 27 negative cases, 8 had disease in the cervical spine and 4 had disease in the shoulder, and the remainder were MR negative with positive electrophysiologic studies.

Of 216 positive cases, 54 cases (one third) were preganglionic; 162 cases (two thirds) were postganglionic injuries. All preganglionic injuries were identified by pseudomeningoceles at one or multiple levels using advanced MRI sequences, especially MR myelography with STIR-MIP ([Fig. 2]). Twelve cases that were < 5 mm were missed on the conventional data set of T1-weighted imaging, T2-weighted imaging, and STIR. These could be due to small size, the partial volume of slice thickness, or flow artifacts hindering image quality.

Postganglionic injuries can be stretch injuries without nerve discontinuity and nerve ruptures with discontinuity. Stretch injuries can be either focal or diffuse. Stretch injuries were seen in 138 cases, of which 84 were focal injuries and 54 were diffuse plexus injuries ([Fig. 3a, b]). Nerve ruptures were seen in 24 cases ([Fig. 3d, e]). Six patients showed extrinsic compressive injury due to muscle contusions and hematoma ([Fig. 4]). All cases were confidently and well demonstrated on coronal STIR-MIP and DWI images with respect to any type of injury (stretch injury or rupture), level of injury (supraclavicular or infraclavicular), whereas only 27 supraclavicular plexus single-root stretch injuries were diagnosed confidently on conventional sequences, and all cases of nerve ruptures were identified. Total obscuration due to rupture and hematoma were also better evaluated by newer techniques, due to single-plane direct visualization of plexus compared with conventional sequences in the sagittal or axial plane in these patients with grossly disturbed anatomy.

Despite the large volume of data with positive findings, this study has the limitation of not being completely blinded.

Conclusion: Advanced MRI techniques such as DWI, STIR-MIP, and MR myelography are both rapid and accurate in identifying and classifying traumatic brachial plexopathy compared with conventional MRI.

Fig. 1 (a) Magnetic resonance myelography depicting normal anatomy of nerve roots (solid white arrows). (b) Diffusion-weighted imaging showing normal anatomy of the brachial plexus. (c) Planning along the plane of the brachial plexus.

Fig. 2 (a) Magnetic resonance myelograph and (b) T1-weighted image showing large fluid signal intensity lesions (pseudomeningoceles) along the course of the brachial plexus extending from roots (pink solid arrows). (c) T1-weighted image and (d) T2-weighted image showing small pseudomeningoceles (red solid arrows).

Fig. 3 (a, b) Short tau inversion recovery (STIR) maximum intensity projection (MIP) images showing increase in signal intensity along nerve roots of stretch injury (solid and straight white arrows). (c, d) STIR-MIP and (e) diffusion-weighted images show complete nerve rupture with discontinuity in the nerve plexus (dotted white arrows).

Fig. 4

Publication History

Article published online:
17 December 2020