Automation of the Fetal Right Myocardial Performance Index to Optimise Repeatability

Abstract

Objectives: To compare the repeatability and degree of absolute agreement of an automated fetal right myocardial performance index (MPI) algorithm with manual measurements along with the impact of MPI observer experience on these two aspects. Methods: Prospective cross-sectional study of 65 uncomplicated singleton pregnancies from 22 to 39 weeks' gestation. Image analysis of double-waveform right MPI measurements was conducted first with a MATLAB automated MPI software and then independently by an experienced and an inexperienced observer. Intraclass correlation coefficients (ICCs) and 95% confidence intervals (95% CI) were used to evaluate manual and automated intra- and interobserver repeatability. In addition, Bland-Altman plots were used to determine the degree of absolute agreement. Results: Successful automation was performed on 63 cases (97%) showing repeatability ICCs of: 0.83 manual intraobserver; 0.77 manual interobserver; 1.00 automated. The degree of absolute agreement between manual and automated values was: inexperienced observer ICC 0.43 (95% CI 0.21-0.62); experienced observer ICC 0.76 (95% CI 0.63-0.85). Conclusion: Automation of right MPI demonstrates a superior reproducibility over manual measurements and reduces the experience required for successful analysis. This may lend a greater clinical applicability to MPI, and future studies to develop an automated universal reference range would be useful.