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Updated: Aug 18, 2026
3D Cine Magnetic Resonance Imaging of Respiratory Motion in Mechanically Ventilated Mice and Rats
Published on: September 19, 2025
Effects of breathing and cardiac motion on spatial resolution in the microscopic imaging of rodents
Wilfried Maï1, Cristian T Badea, Charles T Wheeler
1Center for In Vivo Microscopy, Box 3302, Duke University Medical Center, Durham, NC 27710, USA.
Abstract:
One can acquire high-resolution pulmonary and cardiac images in live rodents with MR microscopy by synchronizing the image acquisition to the breathing cycle across multiple breaths, and gating to the cardiac cycle. The precision with which one can synchronize image acquisition to the motion defines the ultimate resolution limit that can be attained in such studies. The present work was performed to evaluate how reliably the pulmonary and cardiac structures return to the same position from breath to breath and beat to beat across the prolonged period required for MR microscopy. Radiopaque beads were surgically glued to the abdominal surface of the diaphragm and on the cardiac ventricles of anesthetized, mechanically ventilated rats. We evaluated the range of motion for the beads (relative to a reference vertebral bead) using digital microradiography with two specific biological gating methods: 1) ventilation synchronous acquisition, and 2) both ventilation synchronous and cardiac-gated acquisitions. The standard deviation (SD) of the displacement was < or =100 microm, which is comparable to the resolution limit for in vivo MRI imposed by signal-to-noise ratio (SNR) constraints. With careful control of motion, its impact on resolution can be limited. This work provides the first quantitative measure of the motion-imposed resolution limits for in vivo imaging.
Insights
High-resolution in vivo MRI requires synchronizing image acquisition to breathing and cardiac cycles. This study quantifies motion, showing structures return to position within 100 micrometers, enabling precise live rodent imaging.
Area of Science:
- Biomedical Imaging
- Cardiovascular Research
- Pulmonary Research
Background:
- High-resolution imaging of live rodent pulmonary and cardiac systems is crucial for research.
- Image acquisition synchronization to physiological cycles (breathing and cardiac) is key for MR microscopy resolution.
- Understanding motion reliability across prolonged imaging is essential for accurate in vivo MRI.
Purpose of the Study:
- To evaluate the reliability of pulmonary and cardiac structure repositioning during prolonged MR microscopy.
- To quantify motion-induced resolution limits in live rodent imaging.
- To assess the impact of ventilation and cardiac gating on motion control.
Main Methods:
- Surgically implanted radiopaque beads on diaphragm and cardiac ventricles in anesthetized, ventilated rats.
- Digital microradiography used to track bead displacement relative to a vertebral reference.
- Evaluation of two gating methods: ventilation synchronous acquisition and combined ventilation/cardiac gating.
Main Results:
- The standard deviation of bead displacement was less than or equal to 100 micrometers.
- This displacement is comparable to the resolution limits imposed by signal-to-noise ratio in in vivo MRI.
- Demonstrated that motion's impact on resolution can be minimized with precise motion control.
Conclusions:
- This study provides the first quantitative assessment of motion-imposed resolution limits for in vivo imaging.
- Reliable repositioning of pulmonary and cardiac structures within 100 micrometers is achievable.
- Effective motion control is critical for achieving high-resolution MR microscopy in live rodents.
