Comparison of Diffusion MRI Acquisition Protocols for the In Vivo Characterization of the Mouse Spinal Cord: Variability Analysis and Application to an Amyotrophic Lateral Sclerosis Model

PLoS ONE, 2016 · DOI: 10.1371/journal.pone.0161646 · Published: August 25, 2016

Spinal Cord Injury Neuroimaging Neurology

Simple Explanation

This study compares three different dMRI protocols to find the best way to image the spinal cord in mice, especially for studying diseases like ALS. The protocols were tested on healthy mice and mice with a model of ALS to see which one best shows the differences in the spinal cord. The study found that a protocol with a moderate number of diffusion directions and relatively high diffusion weighting worked best for spinal cord imaging.

Study Duration

Not specified

Participants

7 G93A-SOD1 mice and 7 WT-SOD1 mice

Evidence Level

Not specified

Key Findings

1
Intermediate features (12 directions, b = 1200 s/mm2) provided the overall minimum inter- and intra-subject variability in most cases.
2
The protocols with an intermediate or high number of diffusion directions provided the best differentiation between the two groups at week 17, whereas only few local significant differences were highlighted at week 10.
3
A dMRI protocol with a relatively high b-value and a relatively low number of diffusion-encoding gradient directions is optimal for spinal cord imaging.

Research Summary

This study compares three different dMRI protocols applied to investigate the microstructure of both gray (GM) and white matter (WM) in the lumbar region of the mouse spinal cord. The protocols were chosen to probe three different sampling strategies for dMRI with the constraint of an acquisition time of about 35 minutes. The study found that a diffusion tensor scheme with a relatively high b-value and a relatively low number of diffusion-encoding gradient directions is optimal.

Practical Implications

Optimizing Spinal Cord dMRI

The findings could be important for the optimization of acquisition protocols for preclinical and clinical dMRI studies on the spinal cord.

Diagnostic Approach to Motor Neuron Diseases

The optimal protocol allowed a good differentiation between ALS and healthy mice, suggesting a possible relevant role of dMRI in the diagnostic approach to motor neuron diseases.

Tuning Acquisition Parameters

A further tuning of acquisition parameters would be required given the specific conditions in each scenario.

Study Limitations

1
The three considered protocols are different both in terms of number of directions and b-value.
2
Another issue is the assumption that the spinal cord is parallel to the slice direction, which is only approximately true.
3
The lack of a ground truth to validate the results.

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