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graphical abstract plosone

A 4D continuous representation of myocardial velocity fields from tissue phase mapping magnetic resonance imaging

Hjertets sammentreknings- og avslapningshastighet er diagnostisk relevante mål for flere hjertesykdommer, og kan måles med Magnetisk Resonans (MR). Myokardhastighetene representeres i form av MR-bilder, som består av piksler, og er derfor diskrete (i motsetning til kontinuerlige) representasjoner av hjertets lokale bevegelseshastigheter. Mange relevante analyser av bildene antar, imidlertid, støyløse og kontinuerlig representasjoner av myokardhastighetene. I denne artikkelen beskrives en ny bildebehandlingsmetode som konstruerer kontinuerlige, støyreduserte representasjoner av myokardhastigheter fra diskrete hastigheter målt med MR. 

Publisert i Forskningspublikasjoner Torsdag 14. oktober, 2021 - 12:28 | sist oppdatert Torsdag 14. oktober, 2021 - 12:43

Forskere: Bård A. Bendiksen, Gary McGinley, Ivar Sjaastad, Lili Zhang, Emil K. S. Espe.


Myocardial velocities carry important diagnostic information in a range of cardiac diseases, and play an important role in diagnosing and grading left ventricular diastolic dysfunction. Tissue Phase Mapping (TPM) Magnetic Resonance Imaging (MRI) enables discrete sampling of the myocardium’s underlying smooth and continuous velocity field. This paper presents a post-processing framework for constructing a spatially and temporally smooth and continuous representation of the myocardium’s velocity field from TPM data. In the proposed scheme, the velocity field is represented through either linear or cubic B-spline basis functions. The framework facilitates both interpolation and noise reducing approximation. As a proof-of-concept, the framework was evaluated using artificially noisy (i.e., synthetic) velocity fields created by adding different levels of noise to an original TPM data. The framework’s ability to restore the original velocity field was investigated using Bland-Altman statistics. Moreover, we calculated myocardial material point trajectories through temporal integration of the original and synthetic fields. The effect of noise reduction on the calculated trajectories was investigated by assessing the distance between the start and end position of material points after one complete cardiac cycle (end point error). We found that the Bland-Altman limits of agreement between the original and the synthetic velocity fields were reduced after application of the framework. Furthermore, the integrated trajectories exhibited consistently lower end point error. These results suggest that the proposed method generates a realistic continuous representation of myocardial velocity fields from noisy and discrete TPM data. Linear B-splines resulted in narrower limits of agreement between the original and synthetic fields, compared to Cubic B-splines. The end point errors were also consistently lower for Linear B-splines than for cubic. Linear B-splines therefore appear to be more suitable for TPM data. 

Les hele artikkelen her:

Bendiksen BA, McGinley G, Sjaastad I, Zhang L, Espe EKS (2021) A 4D continuous representation of myocardial velocity fields from tissue phase mapping magnetic resonance imaging. PLoS ONE 16(3): e0247826. https://doi.org/10.1371/journal.pone.0247826

Forskningstilskudd: This work was supported by KG Jebsen Center for Cardiac Research (Oslo,Norway), the South-Eastern Norway Regional Health Authority (Oslo, Norway), Familien Blix’ fond til fremme av medisinsk forskning (Oslo,Norway), Olav Raagholt og Gerd Meidel Raagholts stiftelse for forskning (Oslo,Norway). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.