How does 3D planimetry measure mitral valve area in mitral stenosis, and why is it advantageous over 2D planimetry?

• A. All of the above
• B. 3D en face view of the mitral orifice and trace the minimal opening boundary
• C. More accurate and less angle-dependent than 2D planimetry
• D. Especially advantageous with oblique views

Answer: (D)

3D planimetry measures mitral valve area by using a 3D echocardiographic dataset to create a true en face view of the mitral orifice and then tracing the boundary of the opening. By following the actual outline of the orifice in its plane, the area is calculated directly, giving a more faithful measure of the orifice size.

The standout advantage over 2D planimetry is its robustness when views are not perfectly aligned. In oblique or off-axis views, 2D planimetry can foreshorten the orifice and underestimate the area because the measurement plane doesn’t coincide with the true orifice plane. 3D planimetry allows you to orient the image so you see the orifice in its true plane regardless of how the transducer is positioned, making the measurement more accurate and reliable, especially in oblique views.