P486Automated, objective and expert-independent assessment of the analyzability of strain and strain rate in tissue Doppler images in neonates; assessing the strain and strain rate beat-to-beat variation


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Abstract

Purpose: Visual assessment of the analyzability of tissue Doppler images is expert dependent. Analysis of images of poor quality can lead to erogenous measurements. The aim of this study was to assess the feasibility of using the variation in the curves between two consecutive heart-beats for longitudinal strain and strain rate, the beat-to-beat variation (BBV), as automated, objective, expert-independent tools for evaluating the analyzability of longitudinal strain and strain rate in tissue Doppler images in neonates.Methods: Images from four left heart walls, two septum walls and three right heart walls were obtained in 138 examinations from 48 healthy term neonates on day 1, 2 and 3 of life. Two-segment strain and strain rate analyses were performed in 2394 segments. In all segments, the image quality was evaluated visually and the strain BBV and strain rate BBV were estimated.Results: 1739 segments (73%) were deemed to be of sufficient quality for analysis by visual evaluation done by an expert. The intra-rater Kappa score was 0.87 and the inter-rater Kappa score 0.61 for the visual evaluation (p<0.001). Both the strain BBV and the strain rate BBV were higher in images of quality inferior for analysis than in images eligible for analysis (strain BBV 0.602 (0.516-0.689) (mean and 95% CI) vs. 0.130 (0.126-0.136) and strain rate BBV 0.541 (0.519-0.562) vs. 0.248 (0.243-0.254), p<0.001). In the receiver-operator-characteristic (ROC) curves, both strain BBV and strain rate BBV had a sensitivity and specificity of 0.8 for assessing the analyzability based on the visual evaluation. The ROC areas under the curve was 0.87 (0.85-0.88) for the strain BBB and 0.87 (0.85-0.89) for the strain rate BBV (p<0.001). Compared against the visual evaluation by experts, the Kappa scores for identification of images eligible for analysis were 0.57 for the strain rate BBV and 0.58 for the strain BBV (p<0.001).Conclusions: The variation in the curves for strain and for strain rate between two consecutive heart-beats can be used for automated, objective and expert-independent assessment of the analyzability of tissue Doppler images in neonates, aiding the non-experts in the evaluation of the analyzability of the images. The agreements between the automated evaluation and the visual evaluation done by experts were similar to the inter-rater agreement in the visual evaluations between experts, and the specificity and sensitivity for assessing images of sufficient quality for analysis by the automated assessment was acceptable.

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