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Rapid microscopic 3D-diffusion tensor imaging fiber-tracking of mouse brain in vivo by super resolution
Ulysse Gimenez1,2, Jean Christophe Deloulme3, Hana Lahrech4
1University. Grenoble Alpes, Inserm, U1205, BrainTech Lab, 1, place Commandant Nal, 38700, La Tronche, Grenoble, France.
Object:
Exploring mouse brains by rapid 3D-Diffusion Tensor Imaging (3D-DTI) of high spatial resolution (HSR) is challenging in vivo. Here we use the super resolution reconstruction (SRR) postprocessing method to demonstrate its performance on Microtubule-Associated-Protein6 Knock-Out (MAP6-KO) mice.
Materials And Methods:
Two spin-echo DTI were acquired (9.4T, CryoProbe RF-coil): (i)-multislice 2D-DTI, (echo-planar integrating reversed-gradient) acquired in vivo in the three orthogonal orientations (360 μm slice-thickness, 120 × 120 μm in-plane resolution, 56 min scan duration); used in SRR software to reconstruct SRR 3D-DTI with HSR in slice-plane (120 × 120 × 120 µm) and (ii)-microscopic 3D-DTI (µ-3D-DTI), (100 × 100 × 100 µm; 8 h 6 min) on fixed-brains ex vivo, that were removed after paramagnetic contrast-agent injection to accelerate scan acquisition using short repetition-times without NMR-signal sensitivity loss.
Results:
White-matter defects, quantified from both 3D-DTI fiber-tracking were found very similar. Indeed, as expected the fornix and cerebral-peduncle volume losses were - 39% and - 35% in vivo (SRR 3D-DTI) versus - 34% and - 32% ex vivo (µ-3D-DTI), respectively (p<0.001). This finding is robust since the µ-3D-DTI feasibility on MAP6-KO ex vivo was already validated by fluorescent-microscopy of cleared brains.
Discussion:
First performance of the SRR to generate rapid HSR 3D-DTI of mouse brains in vivo is demonstrated. The method is suitable in neurosciences for longitudinal studies to identify molecular and genetic abnormalities in mouse models that are of growing developments.
Insights
Super-resolution reconstruction (SRR) enables rapid, high-spatial-resolution 3D Diffusion Tensor Imaging (3D-DTI) in vivo for mouse brains. This technique effectively identifies white-matter defects in Microtubule-Associated-Protein6 Knock-Out (MAP6-KO) mice.
Area of Science:
- Neuroimaging
- Biophysics
Background:
- High-spatial-resolution 3D Diffusion Tensor Imaging (3D-DTI) in vivo for mouse brains presents significant challenges.
- Microtubule-Associated-Protein6 Knock-Out (MAP6-KO) mice exhibit white-matter defects, making them a relevant model for studying neurological abnormalities.
Purpose of the Study:
- To demonstrate the performance of the super-resolution reconstruction (SRR) postprocessing method for generating rapid, high-spatial-resolution 3D-DTI of mouse brains in vivo.
- To assess the capability of SRR-enhanced 3D-DTI in quantifying white-matter defects in MAP6-KO mice.
Main Methods:
- Acquisition of multislice 2D-DTI data in vivo using a 9.4T scanner with a CryoProbe RF-coil.
- Application of SRR software to reconstruct high-spatial-resolution 3D-DTI from the 2D-DTI data.
- Comparison with ex vivo microscopic 3D-DTI (µ-3D-DTI) on fixed MAP6-KO mouse brains.
Main Results:
- SRR-generated in vivo 3D-DTI successfully identified white-matter defects in MAP6-KO mice, with fornix and cerebral peduncle volume losses of -39% and -35%, respectively.
- These in vivo findings were comparable to ex vivo µ-3D-DTI results (-34% and -32% for fornix and cerebral peduncle, respectively).
- The robustness of the findings was supported by the prior validation of ex vivo µ-3D-DTI using fluorescent microscopy.
Conclusions:
- The SRR method provides the first demonstration of rapid, high-spatial-resolution 3D-DTI acquisition in vivo for mouse brains.
- This technique is well-suited for neuroscientific research, particularly for longitudinal studies involving genetic or molecular abnormalities in mouse models.
