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Published on: October 1, 2014
Boosting the velocity detection limit of 3D single-cell tracking time-lapse MRI by balanced SSFP imaging
Enrica Wilken1, Asli Havlas1, Lydia Wachsmuth1
1Clinic of Radiology, University of Münster, Münster, Germany.
Purpose:
Time-lapse MRI allows for the dynamic tracking of single iron-labeled cells. However, the time required for spatial encoding creates a temporal blur and, therefore, a limited ability to resolve moving cells. To study fast moving cells, such as rolling immune cells along the endothelium during inflammatory processes, advanced accelerated acquisition techniques are required.
Methods:
Balanced SSFP (bSSFP) imaging is applied to phantom and in vivo murine brain time-lapse MRI measurements at 9.4 T. Its detection capability of moving iron-labeled cells is compared with conventional gradient echo imaging (GRE) for 2D Cartesian sampling and evaluated for fully sampled and accelerated reconstructions with compressed sensing for 3D interleaved radial sampling in bSSFP.
Results:
Both phantom and in vivo time-lapse MRI measurements show that single cells can be followed dynamically using bSSFP. High temporal resolution of less than 2 min reduces geometric distortion. The velocity detection limit increases to 0.8 mm/min in vitro and previously hidden fast-moving cells are recovered. Interleaved 3D radial sampling enables 3D cell tracking and simultaneous imaging at varying acceleration factors. Fivefold acceleration with compressed sensing optimizes cell visibility, image quality, and temporal resolution.
Conclusion:
bSSFP time-lapse MRI improves single-cell tracking by enhancing temporal resolution. In vitro, the velocity detection limit is increased fourfold compared to conventional GRE. Interleaved 3D radial bSSFP offers whole-brain coverage at isotropic spatial resolution and retrospective reconstruction of both fully sampled and high temporal resolution images.
Insights
Balanced steady-state free precession (bSSFP) MRI enhances dynamic tracking of single iron-labeled cells. This advanced technique improves temporal resolution, enabling the recovery of fast-moving cells previously undetectable with conventional methods.
Area of Science:
- Magnetic Resonance Imaging (MRI)
- Cellular Dynamics
- Biomedical Engineering
Background:
- Time-lapse MRI is crucial for tracking single iron-labeled cells dynamically.
- Conventional MRI techniques suffer from temporal blur due to spatial encoding, limiting the resolution of moving cells.
- Studying fast-moving cells, like immune cells during inflammation, necessitates accelerated acquisition techniques.
Purpose of the Study:
- To evaluate balanced steady-state free precession (bSSFP) imaging for enhanced time-lapse MRI of single iron-labeled cells.
- To compare the cell detection capabilities of bSSFP with conventional gradient echo imaging (GRE).
- To assess accelerated 3D interleaved radial sampling with compressed sensing for improved cell tracking.
Main Methods:
- bSSFP imaging was applied to phantom and in vivo murine brain time-lapse MRI at 9.4 T.
- Cell detection was compared between bSSFP and conventional GRE with 2D Cartesian sampling.
- Accelerated 3D interleaved radial sampling with compressed sensing was evaluated for bSSFP.
Main Results:
- bSSFP successfully enabled dynamic tracking of single cells in both phantom and in vivo experiments.
- High temporal resolution (<2 min) reduced geometric distortion, increasing the velocity detection limit to 0.8 mm/min in vitro.
- Accelerated 3D radial bSSFP with compressed sensing optimized cell visibility, image quality, and temporal resolution, allowing for 3D cell tracking.
Conclusions:
- bSSFP time-lapse MRI significantly improves single-cell tracking by enhancing temporal resolution.
- The velocity detection limit in vitro was increased fourfold compared to conventional GRE.
- Interleaved 3D radial bSSFP provides whole-brain coverage with isotropic resolution and allows retrospective reconstruction for high temporal resolution imaging.
