Abstract 11609: Developing a Novel Method for Measuring Relative Lung Perfusion at the Catheterization Laboratory

Abstract

Background: Maldistribution of pulmonary blood flow (Qp) is common in patients with congenital heart disease and is associated with worse clinical outcomes. Currently, measurement of Qp-split can only be performed outside the catheterization laboratory, using either lung perfusion scans or cardiac magnetic resonance imaging. Aim: We sought to develop and evaluate a tool for measuring Qp-split using readily available fluoroscopy sequences. Methods: A retrospective cohort study of patients with conotruncal anomalies who underwent perfusion scan and subsequent cardiac catheterization. Inclusion criteria were non-selective angiogram of pulmonary vasculature, oblique angulation ≤20°, and an adequate view of both lung fields. A method was developed and implemented in 3D Slicer to calculate the amount of contrast that entered each lung field from the start of contrast-injection and until the onset of levophase. The predicted perfusion distribution was compared to the distribution measured by lung scan. Results: In total 32% (79/249) of screened studies met inclusion criteria. There was strong correlation between the predicted Qp-split and the measured Qp-split (R 2 =0.83, p<0.001) with median absolute error (MAE) of 6%. Bias was not systematically worse at either extreme of flow distribution. Factors associated with better prediction were smaller BSA, younger age, right ventricle (vs. pulmonary artery) angiograms, and cranial angulations ≤20°. In cases with one or more of these conditions (n=40), the prediction achieved R 2 =0.87, MAE of 5.5%, and 78% of predictions were within 10% of true flow. Conclusions: Data from conventional angiograms can be used to provide accurate real-time measurement of relative perfusion of the left and right lungs. This has the potential to reduce unnecessary testing, associated costs, and radiation exposure.