Accelerated magnetic resonance imaging tissue phase mapping of the rat myocardium using compressed sensing with iterative soft-thresholding
Hjertets sammentreknings- og avslapningshastighet er diagnostisk relevante mål for flere hjertesykdommer, og kan måles med vevsfasekontrast Magnetisk Resonans (MR). Hastighetene kan også brukes for å beregne andre mål på regional funksjon, som strain og strain rate. Langsom opptakstid kan, imidlertid, lede til målefeil forårsaket av endringer i f.eks. hjerterate underveis i opptaket. Målet med denne studien var å utvikle en ny målemetode og databearbeidingsmetode basert på «compressed sensing», for å akselerere opptakstiden for vevsfasekontarst MR.
Publisert i Forskningspublikasjoner Torsdag 14. oktober, 2021 - 11:36 | sist oppdatert Torsdag 14. oktober, 2021 - 11:47
Tissue Phase Mapping (TPM) MRI can accurately measure regional myocardial velocities and strain. The lengthy data acquisition, however, renders TPM prone to errors due to variations in physiological parameters, and reduces data yield and experimental throughput. The purpose of the present study is to examine the quality of functional measures (velocity and strain) obtained by highly undersampled TPM data using compressed sensing reconstruction in infarcted and non-infarcted rat hearts.
Three fully sampled left-ventricular short-axis TPM slices were acquired from 5 non-infarcted rat hearts and 12 infarcted rat hearts in vivo. The datasets were used to generate retrospectively (simulated) undersampled TPM datasets, with undersampling factors of 2, 4, 8 and 16. Myocardial velocities and circumferential strain were calculated from all datasets. The error introduced from undersampling was then measured and compared to the fully sampled data in order to validate the method. Finally, prospectively undersampled data were acquired and compared to the fully sampled datasets.
Bland Altman analysis of the retrospectively undersampled and fully sampled data revealed narrow limits of agreement and little bias (global radial velocity: median bias = -0.01 cm/s, 95% limits of agreement = [-0.16, 0.20] cm/s, global circumferential strain: median bias = -0.01%strain, 95% limits of agreement = [-0.43, 0.51] %strain, all for 4x undersampled data at the mid-ventricular level). The prospectively undersampled TPM datasets successfully demonstrated the feasibility of method implementation.
Through compressed sensing reconstruction, highly undersampled TPM data can be used to accurately measure the velocity and strain of the infarcted and non-infarcted rat myocardium in vivo, thereby increasing experimental throughput and simultaneously reducing error introduced by physiological variations over time.
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Forskningstilskudd: This work was supported by South-Eastern Norway Regional Health Authority (Oslo, Norway), KG Jebsen Center for Cardiac Research and Center for Heart Failure Research (Oslo,Norway). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.