Left ventricular flow propagation velocity measurement: Is it cast in stone?

Area of Science:

• Cardiovascular Imaging
• Medical Physics
• Cardiac Physiology

Background:

• Left ventricular (LV) flow propagation velocity (Vp) is a key diastolic function parameter.
• Accurate Vp measurement is crucial but challenged by inflow jet direction and LV size variations.

Purpose of the Study:

• To investigate phase contrast magnetic resonance imaging (PC-MRI) for Vp measurement.
• To compare three Vp measurement techniques: non-adaptive (NA), adaptive positions (AP), and adaptive vectors (AV).
• To assess the impact of measurement position and LV size on Vp accuracy.

Main Methods:

• Comparison of NA, AP, and AV methods for Vp measurement using PC-MRI.
• Data acquired from nine healthy volunteers and nine post-infarct patients.
• Measurements taken at four positions: 1/3, 1/2, 2/3, and 4 cm from the mitral valve.

Main Results:

• Vp measurements were significantly influenced by inflow jet direction and measurement position.
• NA and AP methods overestimated Vp, especially in dilated LV.
• The AV method demonstrated the strongest correlation with isovolumic relaxation myocardial strain rate (r=0.53, p<0.05).
• Significant differences in mean Vp were observed between healthy and post-infarct groups using the AV method at 1/2, 2/3, and 4 cm distances.

Conclusions:

• The AV method is superior for Vp assessment, showing better correlation with myocardial strain.
• The AV method at the one-half distance is recommended for assessing diastolic dysfunction.
• This approach accounts for variations in LV size and inflow jet direction.