Defning the optimal temporal and spatial resolution for cardiovascular magnetic resonance imaging feature tracking.

Background: Myocardial deformation analyses using cardiovascular magnetic resonance (CMR) feature tracking (CMR-FT) have incremental value in the assessment of cardiac function beyond volumetric analyses. Since guidelines do not recommend specifc imaging parameters, we aimed to defne optimal spatial and temporal resolutions for CMR cine images to enable reliable post-processing. Methods: Intra- and inter-observer reproducibility was assessed in 12 healthy subjects and 9 heart failure (HF) patients. Cine images were acquired with diferent temporal (20, 30, 40 and 50 frames/cardiac cycle) and spatial reso‑ lutions (high in-plane 1.5×1.5 mm through-plane 5 mm, standard 1.8×1.8 x 8mm and low 3.0×3.0 x 10mm). CMR-FT comprised left ventricular (LV) global and segmental longitudinal/circumferential strain (GLS/GCS) and associated systolic strain rates (SR), and right ventricular (RV) GLS. Results: Temporal but not spatial resolution did impact absolute strain and SR. Maximum absolute changes between lowest and highest temporal resolution were as follows: 1.8% and 0.3%/s for LV GLS and SR, 2.5% and 0.6%/s for GCS and SR as well as 1.4% for RV GLS. Changes of strain values occurred comparing 20 and 30 frames/cardiac cycle including LV and RV GLS and GCS (p<0.001–0.046). In contrast, SR values (LV GLS/GCS SR) changed signifcantly com‑ paring all successive temporal resolutions (p<0.001–0.013). LV strain and SR reproducibility was not afected by either temporal or spatial resolution, whilst RV strain variability decreased with augmentation of temporal resolution. Conclusion: Temporal but not spatial resolution signifcantly afects strain and SR in CMR-FT deformation analyses. Strain analyses require lower temporal resolution and 30 frames/cardiac cycle ofer consistent strain assessments, whilst SR measurements gain from further increases in temporal resolution. [ABSTRACT FROM AUTHOR]