Right ventricular ejection fraction with cardiac magnetic resonance using a wall motion score

Area of Science:

• Cardiology
• Medical Imaging
• Diagnostic Techniques

Background:

• Cardiac magnetic resonance (CMR) volumetric method for right ventricular ejection fraction (RVEF) assessment is complex due to right ventricular geometry.
• Expertise is required for accurate RVEF measurement using traditional volumetric techniques.

Purpose of the Study:

• To introduce and validate a novel method for evaluating RVEF in CMR based on the wall motion score index (WMSI).
• To establish a correlation and regression equation between WMSI and volumetric RVEF.

Main Methods:

• Visual assessment of right ventricular wall motion using an eight-segment model.
• Calculation of WMSI and its correlation with volumetric RVEF.
• Derivation of a regression equation to estimate RVEF from WMSI and validation using Bland-Altman analysis.

Main Results:

• A strong negative correlation (Spearman's Rho=-0.69) was found between WMSI and volumetric RVEF.
• A regression equation (RVEF=80-22×WMSI) demonstrated good agreement with the volumetric method (mean bias -3%, SD ±7.5%).
• A WMSI cut-off of ≥1.5 accurately predicted RVEF <45% (92% accuracy), identifying a high-risk group.

Conclusions:

• The WMSI method provides an accurate and well-correlated alternative to the volumetric method for RVEF assessment in CMR.
• WMSI ≥1.5 is an effective threshold for identifying patients with prognostically significant low RVEF (<45%).