Automated, Objective and Expert-Independent Assessment of the Analyzability of Strain and Strain Rate in Tissue Doppler Images in Term Neonates by Analysis of Beat-to-Beat Variation

The variation in longitudinal strain and strain rate (SR) between two consecutive heartbeats (beat-to-beat-variation, BBV) was used to evaluate the analyzability of longitudinal strain and SR in tissue Doppler images in term neonates. Strain and SR BBV analysis and visual evaluation of analyzability were performed in 2394 segments; 1739 segments (73%) were deemed to be analyzable by visual evaluation, with an intra-rater κ score of 0.87 and inter-rater κ score of 0.61 (p < 0.001). Compared against visual evaluation, the κ scores for identification of analyzable segments were 0.57 based on SR BBV and 0.58 based on strain BBV (p < 0.001). The areas under the receiver operating characteristic curves for identification of analyzable segments were 0.87 (0.85-0.88) for strain BBV and 0.87 (0.85-0.89) for SR BBV (p < 0.001). For both BBVs, the sensitivity for identification of analyzable segments was 77% at a specificity of 80%. Analysis of BBV can be used for automated, objective and expert-independent assessment of analyzability.