Calculating Relative Lung Perfusion Using Fluoroscopic Sequences and Image Analysis: The Fluoroscopic Flow Calculator

Area of Science:

• Cardiology
• Medical Imaging
• Pediatric Congenital Heart Disease

Background:

• Pulmonary blood flow maldistribution in congenital heart disease (CHD) affects patient outcomes.
• Current methods for measuring lung perfusion require specialized equipment outside the catheterization lab.
• A need exists for a more accessible tool to assess relative pulmonary perfusion.

Purpose of the Study:

• To develop and validate a novel method for measuring relative lung perfusion using conventional fluoroscopy sequences.
• To enable real-time assessment of pulmonary blood flow distribution within the catheterization laboratory.

Main Methods:

• A retrospective cohort study analyzed patients with conotruncal anomalies undergoing lung perfusion scans and cardiac catheterization.
• A 3D Slicer extension (SlicerHeart) was used to calculate contrast distribution in lung fields from angiograms.
• The developed method's predictions were compared against measured pulmonary blood flow for correlation, accuracy, and bias.

Main Results:

• A strong correlation (R²=0.83) was found between predicted and measured pulmonary blood flow splits.
• The method achieved a median absolute error of 6%, with 72% of predictions within 10% of the true value.
• Predictions were more accurate in younger patients (0-2 years), with right ventricle injections, or using angulations ≤20° (R²=0.87, error 5.5%).

Conclusions:

• A feasible method for measuring relative lung perfusion using conventional angiograms was demonstrated.
• Real-time lung perfusion assessment in the catheterization lab can potentially minimize unnecessary tests, costs, and radiation.
• Further optimization and validation of this novel technique are recommended.