Fast retrospectively triggered local pulse-wave velocity measurements in mice with CMR-microscopy using a radial...

Area of Science:

• Cardiovascular Imaging
• Medical Physics
• Biomedical Engineering

Background:

• Aortic pulse-wave velocity (PWV) is a key indicator of cardiovascular risk.
• Non-invasive MRI methods for measuring PWV in mice exist but typically require cardiac and respiratory gating hardware.
• There is a need for simpler, more robust methods for PWV assessment in preclinical cardiovascular research.

Purpose of the Study:

• To develop and validate a self-gated magnetic resonance imaging (MRI) technique for measuring local PWV in the mouse aorta.
• To eliminate the requirement for external triggering probes, simplifying the measurement procedure.
• To assess the feasibility and accuracy of this novel method compared to conventional triggered techniques.

Main Methods:

• A retrospectively triggered radial Phase Contrast (PC) MRI sequence was employed in 6-month-old wild-type C57BL/6J mice (n=6).
• A self-gating navigator signal was extracted from asymmetric radial projections and processed for retrospective cardiac and respiratory gating.
• The flow-area (QA) method was used to determine PWV from reconstructed Cine images of aortic motion, volume flow (Q), and cross-sectional area (A).

Main Results:

• A self-gating signal was successfully extracted in all animals, enabling retrospective gating and Cine reconstruction.
• The self-gated method yielded PWV values of 2.3±0.2 m/s, consistent with triggered Cartesian (2.4±0.2 m/s) and triggered radial (2.3±0.2 m/s) measurements.
• The radial trajectory's robustness allowed for an acceleration factor of over two compared to prospectively triggered Cartesian sampling.

Conclusions:

• Extraction of a self-gating signal using a radial flow-encoding sequence is feasible in mice.
• This retrospective self-gated method allows for robust, fast, and non-invasive local PWV measurements without additional trigger hardware.
• The technique simplifies PWV assessment in mice, potentially improving cardiovascular risk evaluation in preclinical studies.