Characterizing valve dynamics in mice by high-resolution cine-MRI

Area of Science:

• Cardiovascular Imaging
• Medical Diagnostics
• Animal Models

Background:

• Calcific aortic valve disease (CAVD) involves progressive valvular sclerosis and calcification, leading to aortic orifice narrowing and impaired function.
• Accurate assessment of aortic valve dynamics is crucial for understanding CAVD progression and evaluating therapeutic interventions.

Purpose of the Study:

• To apply high-resolution cine-MRI for quantitative analysis of aortic valve dynamics in a mouse model of CAVD.
• To assess the efficacy of cine-MRI in detecting aortic valve dysfunction and stenosis in this model.

Main Methods:

• LDLr-/- ApoB100/100 mice were fed either a Western diet (WD) or a standard diet (control) for 22 weeks.
• High-resolution cine-MRI (7T scanner) was used to image the aortic valve cross-section and quantify orifice area throughout the cardiac cycle.
• MRI findings were correlated with echocardiographic and histopathologic results.

Main Results:

• Mice on the WD exhibited clear aortic valve dysfunction compared to controls (P < 0.001).
• MRI revealed significant narrowing of the aortic valve orifice area (14%, P < 0.05) and reduced ejection fraction (-11%, P < 0.01) in WD mice.
• Histology confirmed more severe aortic stenosis in WD mice (34%, P < 0.05), and MRI/echocardiography ejection fraction correlated with stenosis severity.

Conclusions:

• Cine-MRI enables quantitative analysis of aortic valve orifice dynamics over the cardiac cycle in mice.
• The technique clearly visualized aortic valve cusps and detected time-dependent aortic valve dysfunction.
• High-resolution cine-MRI is a valuable tool for assessing aortic valve disease in preclinical models.