Development and feasibility of quantitative dynamic cardiac imaging for mice using μSPECT

Area of Science:

• Cardiovascular Imaging
• Molecular Imaging
• Mouse Models

Background:

• Coronary microvascular disease (CMVD) lacks mechanistic understanding.
• Mouse models are crucial for studying CMVD molecular processes.
• Quantitative imaging is needed to assess coronary microvascular function in mice.

Purpose of the Study:

• To develop quantitative mouse imaging techniques for assessing coronary microvascular function.
• To enable mechanistic studies of coronary microvascular disease (CMVD) using mouse models.

Main Methods:

• Utilized 99mTc-sestamibi with MILabs U-SPECT+ system for myocardial blood flow measurement in mice.
• Determined influx rate constant (K1) and intramyocardial blood volume (IMBV) using SPECT imaging.
• Employed 99mTc and stannous pyrophosphate for red blood cell imaging to assess IMBV.

Main Results:

• Established a quantitative framework for measuring K1 (0.57 ± 0.08 min⁻¹) and IMBV changes.
• Demonstrated a 22.9 ± 3.3% increase in IMBV in wild-type mice under hyperemic conditions.
• Derived Renkin-Crone parameters (α=0.99, β=0.39) for 99mTc-sestamibi extraction fraction.

Conclusions:

• Successfully developed a non-invasive µSPECT-based quantitative imaging framework for mouse microvascular function.
• This method allows for the measurement of K1 and changes in IMBV, advancing CMVD research in mouse models.