Cardiac magnetic resonance feature-tracking analysis of left atrial volumes and function in standard vs left-atrial focused images. (3rd October 2022) - Tondi, L
Abstract: Background: Left atrial (LA) volume and function have shown prognostic value in several cardiac conditions. Routine cardiac magnetic resonance (CMR) evaluation of the LA is obtained from standard 2- and 4-chamber long-axis cine images focused on the left ventricle. Previous echocardiographic data showed that LA-focused apical views provide a more accurate estimation of LA maximum volume, as compared to standard apical images. CMR LA-focused imaging could improve the accuracy of LA morpho-functional analysis. CMR feature-tracking (CMR-FT) analysis is emerging as a feasible semi-automatic tool for the evaluation of LA volumes and function. Purpose: To investigate the potential of LA-focused CMR cine images using LA CMR-FT analysis. Methods: 100 consecutive patients clinically referred to CMR were included in this prospective, observational, multicenter study. LA volumes (LAVmax, LAVmin), emptying fraction (EF), atrial strain reservoir (ɛs), conduit (ɛe), booster (ɛa) and strain rate reservoir (SRɛs) were calculated by CMR-FT analysis on both standard and LA-focused 2- and 4-chamber long-axis cine images. Manual segmentation of a short-axis cine stack covering the LA was used as the reference method (RefMeth) for LA volumes and EF. Results: In comparison to the RefMeth, the standard acquisitions underestimated LA volumes (LAVmax: bias = −8ml, LOA = +20, −35ml; LAVmin: bias = −6 ml, LOA = +15, −27ml) and slightly overestimated EF (bias = +3%, LOA = +17, −11%). Conversely, LA-focused images provided a more accurate estimation (LAV max bias = −1ml, LOA = +11, −9ml; LAV min bias = −2ml, LOA = +12, −7ml) and EF (bias = −2%, LOA = +9, −12%). All three LA strain (εs: bias 7%, LOA = 25, −11%; εe: bias 4%, LOA = 15, −8%; εa: bias 3%, LOA = 14, −8%) and SRεs (bias 0.2 s –1, LOA = 1.13, −0.7 s –1 ) were significantly higher in standard vs LA-focused images (all p<0.001). Conclusions: Assessment of LA volumes using CMR-FT applied to dedicated LA-focused long-axis cine images is more accurate than the use of standard acquisitions. LA strain and SRɛs obtained from LA-focused images are significantly lower than those obtained from standard LA acquisitions, possibly due to the inclusion in LA-focused images of LA posterior wall, where pulmonary veins convey and atrial deformation is blunted. Funding Acknowledgement: Type of funding sources: None.