4.7-T diffusion tensor imaging of acute traumatic peripheral nerve injury

Abstract

<jats:p>Diagnosis and management of peripheral nerve injury is complicated by the inability to assess microstructural features of injured nerve fibers via clinical examination and electrophysiology. Diffusion tensor imaging (DTI) has been shown to accurately detect nerve injury and regeneration in crush models of peripheral nerve injury, but no prior studies have been conducted on nerve transection, a surgical emergency that can lead to permanent weakness or paralysis. Acute sciatic nerve injuries were performed microsurgically to produce multiple grades of nerve transection in rats that were harvested 1 hour after surgery. High-resolution diffusion tensor images from ex vivo sciatic nerves were obtained using diffusion-weighted spin-echo acquisitions at 4.7 T. Fractional anisotropy was significantly reduced at the injury sites of transected rats compared with sham rats. Additionally, minor eigenvalues and radial diffusivity were profoundly elevated at all injury sites and were negatively correlated to the degree of injury. Diffusion tensor tractography showed discontinuities at all injury sites and significantly reduced continuous tract counts. These findings demonstrate that high-resolution DTI is a promising tool for acute diagnosis and grading of traumatic peripheral nerve injuries.</jats:p>

Visualization of nerve fibers around the carotid bifurcation with use of a 9.4 Tesla microscopic magnetic resonance diffusion tensor imaging with tractography

“…In recent years, DTI, an MRI technique that allows us to delineate the axonal organizations, has been reported to be useful in understanding nerve anatomy 3,12-17 and nerve disorders. [4][5][6][7]18 In the head and neck region, reports are limited. Akter et al 8 patient with C4 nerve schwannoma.…”

“…Recently, techniques called diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT) have been reported to be useful in visualizing both central and peripheral nerve fibers. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] The DTI technique is an MR acquisition modality that measures the diffusion anisotropy of water molecules. Because water molecules tend to diffuse along axons, neurofilaments, and nerve sheaths, DTI makes it possible to delineate the orientation of nerve fibers.…”

Quantitative magnetic resonance (MR) neurography for evaluation of peripheral nerves and plexus injuries

“…Besides the assessment of nerve continuity by morphological and also functional neurographic techniques, the evaluation of the several derived parameters from DWN and DTN may help to decide further therapeutic options (74). Also, these techniques may have a potential role for in vivo surgery planning and selection of the segments of PN candidates for autologous nerve graft or to discard them in basis to their functional characteristics (75).…”

Probabilistic Assessment of Nerve Regeneration with Diffusion MRI: Validation in Rat Models of Peripheral Nerve Trauma

“…Although electromyography and nerve conduction studies (NCS) are the current standards to assess nerve regeneration in extremities 7 , these methods are incapable of monitoring and quantifying nerve recovery until muscles are reinnervated. Thus, with no insight into the recovery process, physicians are forced to delay second interventions until the time at which axons should be reaching the muscular end plate 8 , which increases the probability of irreversible muscular atrophy 9,10 .…”

“…While previous MRI studies have demonstrated the relationship between diffusion MRI indices in nerves and function or histology 8,25,27,28 , no studies have evaluated the ability of diffusion MRI to stratify successful from unsuccessful repairs after TPNI. In this study, we propose a probabilistic model of nerve recovery based on multiple diffusion MRI parameters.…”