Dataset Information

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

ABSTRACT: Nerve regeneration after injury must occur in a timely fashion to restore function. Unfortunately, current methods (e.g., electrophysiology) provide limited information following trauma, resulting in delayed management and suboptimal outcomes. Herein, we evaluated the ability of diffusion MRI to monitor nerve regeneration after injury/repair. Sprague-Dawley rats were divided into three treatment groups (sham?=?21, crush?=?23, cut/repair?=?19) and ex vivo diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) was performed 1-12 weeks post-surgery. Behavioral data showed a distinction between crush and cut/repair nerves at 4 weeks. This was consistent with DTI, which found that thresholds based on the ratio of radial and axial diffusivities (RD/AD?=?0.40?±?0.02) and fractional anisotropy (FA?=?0.53?±?0.01) differentiated crush from cut/repair injuries. By the 12^th week, cut/repair nerves whose behavioral data indicated a partial recovery were below the RD/AD threshold (and above the FA threshold), while nerves that did not recover were on the opposite side of each threshold. Additional morphometric analysis indicated that DTI-derived normalized scalar indices report on axon density (RD/AD: r?=?-0.54, p?

SUBMITTER: Manzanera Esteve IV

PROVIDER: S-EPMC6928159 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

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

Manzanera Esteve Isaac V IV Farinas Angel F AF Pollins Alonda C AC Nussenbaum Marlieke E ME Cardwell Nancy L NL Kang Hakmook H Does Mark D MD Thayer Wesley P WP Dortch Richard D RD

Scientific reports 20191223 1

Nerve regeneration after injury must occur in a timely fashion to restore function. Unfortunately, current methods (e.g., electrophysiology) provide limited information following trauma, resulting in delayed management and suboptimal outcomes. Herein, we evaluated the ability of diffusion MRI to monitor nerve regeneration after injury/repair. Sprague-Dawley rats were divided into three treatment groups (sham = 21, crush = 23, cut/repair = 19) and ex vivo diffusion tensor imaging (DTI) and diffus ...[more]

PMID: 31873165

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Project description:Objectives: Magnetic resonance-guided focused ultrasound (MRgFUS) is a non-invasive targeted tissue ablation technique that can be applied to the nervous system. Diffusion weighted imaging (DWI) can visualize and evaluate nervous system microstructure. Tractography algorithms can reconstruct fiber bundles which can be used for treatment navigation and diffusion tensor imaging (DTI) metrics permit the quantitative assessment of nerve microstructure in vivo. There is a need for imaging tools to aid in the visualization and quantitative assessment of treatment-related nerve changes in MRgFUS. We present a method of peripheral nerve tract reconstruction and use DTI metrics to evaluate the MRgFUS treatment effect. Materials and Methods: MRgFUS was applied bilaterally to the sciatic nerves in 6 piglets (12 nerves total). T1-weighted and diffusion images were acquired before and after treatment. Tensor-based and constrained spherical deconvolution (CSD) tractography algorithms were used to reconstruct the nerves. DTI metrics of fractional anisotropy (FA), and mean (MD), axial (AD), and radial diffusivities (RD) were measured to assess acute (<1-2 h) treatment effects. Temperature was measured in vivo via MR thermometry. Histological data was collected for lesion assessment. Results: The sciatic nerves were successfully reconstructed in all subjects. Tract disruption was observed after treatment using both CSD and tensor models. DTI metrics in the targeted nerve segments showed significantly decreased FA and increased MD, AD, and RD. Transducer output power was positively correlated with lesion volume and temperature and negatively correlated with MD, AD, and RD. No correlations were observed between FA and other measured parameters. Conclusions: DWI and tractography are effective tools for visualizing peripheral nerve segments for targeting in non-invasive surgical methods and for assessing the microstructural changes that occur following MRgFUS treatment.

Dataset Information

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

Publications

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

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