Influence of equipment and settings on myocardial performance index repeatability and definition of settings to achieve optimal reproducibility

SM Lobmaier; M Cruz-Lemini; B Valenzuela-Alcaraz; JU Ortiz; JM Martinez; E Gratacós; F Crispi

doi:10.1055/s-0034-1388045

Geburtshilfe und Frauenheilkunde, Table of Contents

Influence of equipment and settings on myocardial performance index repeatability and definition of settings to achieve optimal reproducibility

SM Lobmaier ¹^,², M Cruz-Lemini ², B Valenzuela-Alcaraz ², JU Ortiz ¹^,², JM Martinez ², E Gratacós ², F Crispi ²

¹Frauenklinik am Klinikum rechts der Isar der Technischen Universität, München, Germany
²Maternal-Fetal Medicine Department, Institut Clinic de Ginecologia, Obstetricia i Neonatologia, Hospital Clinic; Fetal and Perinatal Medicine Research Group, Institut d'Investigacions Biomèdiques August Pi i Sunyer, University of Barcelona, Barcelona, Spain

Abstract

Objectives: Myocardial performance index (MPI) is increasingly used in fetal medicine research, but wide variations in normal values are still reported. The aim of this study was to compare left MPI values and reproducibility using different settings and ultrasound equipment in order to standardize optimal machine settings.

Methods: Left MPI was prospectively evaluated performing conventional Doppler in 62 fetuses (28 to 36 weeks) using different settings (changing sweep speed, gain and wall motion filter (WMF)) and two different ultrasound devices (Siemens Antares, Siemens; Voluson E8, General Electric). Intraclass coefficients of agreement (ICC) were calculated.

Results: Using baseline settings, mean MPI was 0.44 (SD 0.05) with an ICC of 0.81. Decreasing the sweep speed resulted in decreasing average MPI values (0.43) and decreasing ICC (0.61). Lowering gain also influenced average MPI values (0.46) and ICC (0.76). Raising gain resulted in similar MPI values (0.45) with better ICC (0.90) as compared to baseline settings. Raising WMF provided the best ICC (0.94) compared to the other settings. Changing the ultrasound equipment resulted in ICC of 0.64. The optimal settings to achieve the highest reproducibility in MPI were sweep speed 8 cm/s, gain 60 dB and WMF 281 Hz for Siemens; and sweep speed 5 cm/s, gain -10 dB and WMF 210 Hz for Voluson.

Conclusions: Changing ultrasound settings or equipment may affect MPI values calculation and repeatability. A strict standardization of methods improves the variability of this parameter for fetal cardiac function assessment.