The quantification of pulmonary valve haemodynamics using MRI

Area of Science:

• Cardiovascular Imaging
• Medical Physics

Background:

• Pulmonary valve hemodynamics are crucial for assessing cardiovascular health.
• Accurate quantification of pulmonary valve function is essential in patients with congenital heart disease.

Purpose of the Study:

• To determine the optimal slice location within the pulmonary root for quantifying pulmonary valve hemodynamics using magnetic resonance (MR) phase velocity mapping.
• To evaluate the impact of slice position on measurements of systolic and diastolic blood flow volume and cardiac index.

Main Methods:

• Magnetic resonance (MR) phase velocity mapping was performed on 15 patients with congenital aortic valve disease.
• Systolic (Q(SYS)) and diastolic (Q(DIAS)) blood flow volumes and cardiac index (CI) were measured at four pulmonary artery locations.
• Diastolic flow volume changes were calculated relative to the slice closest to the pulmonary valve.

Main Results:

• A significant increase in mean diastolic flow volume (3.4 to 7.7 ml) was observed between slice positions 0.5 cm and 2 cm from the annulus (p = 0.01).
• No significant change in cardiac index (CI) was found over the same distance (3.4-3.7 l/min/m2, p = 0.14).
• Diastolic flow volume changed by 4.4 ml for a 1.5 cm axial position change.

Conclusions:

• Slice proximity to the pulmonary valve minimizes errors due to compliance.
• Valve motion can lead to underestimation of diastolic pulmonary valve flow or regurgitant volume.
• This underestimation may be significant in mild to moderate regurgitation or for temporal measurements.