Left atrial FT is feasible on MRI cine images and its addition to conventional analysis tools might enhance the diagnosis value of MRI in many heart diseases.

Importance of left atrial (LA) phasic function evaluation is increasingly recognized for its incremental value in terms of prognosis and risk stratification. LA phasic deformation in the pathway of normal aging has been characterized using echocardiographic speckle tracking. However, no data are available regarding age-related variations using feature-racking (FT) techniques from standard cine magnetic resonance imaging (MRI). We studied 94 healthy adults (41 ± 14 yr, 47 women), who underwent MRI and Doppler echocardiography on the same day for left ventricular (LV) diastolic function evaluation. From cine MRI, longitudinal strain and strain rate, radial motion fraction, and radial relative velocity, respectively, corresponding to the reservoir, conduit, and LA contraction phases, were measured using dedicated FT software. Longitudinal strain and radial motion fraction decreased gradually and significantly with aging for both reservoir ( r > 0.31, P < 0.003) and conduit ( r > 0.54, P < 0.001) phases, whereas they remained unchanged during the LA contraction phase. Subsequently, the LA contraction-to-reservoir ratio increased significantly with age ( r > 0.44, P < 0.001). Longitudinal strain rate and radial relative velocity significantly decreased with age (reservoir: r = 0.39, P < 0.001, conduit: r > 0.54, P < 0.001), and these associations tended to be stronger in women than in men. Finally, associations of LA functional indexes with age were stronger in individuals with lower transmitral early-to-atrial maximal velocity ratio and mitral annulus maximal longitudinal velocity, as well as higher transmitral early maximal-to-mitral annulus maximal longitudinal velocity ratio, highlighting the LV-LA interplay. Age-related changes in LA phasic function indexes were quantified by cine MRI images using a FT technique and were significantly related to age and LV diastolic function.

Background: Diastolic dysfunction is a major cause of morbidity in obese individuals. We aimed to assess the ability of magnetic resonance imaging (MRI) derived left atrial (LA) strain to detect early diastolic dysfunction in individuals with obesity and type 2 diabetes, and to explore the association between cardiac adipose tissue and LA function.Methods: Twenty patients with obesity and T2D (55 ± 8 years) and nineteen healthy controls (48 ± 13 years) were imaged using cine steady state free precession and 2-point Dixon cardiovascular magnetic resonance. LA function was quantified using a feature tracking technique with definition of phasic longitudinal strain and strain rates, as well as radial motion fraction and radial velocities.Results: Systolic left ventricular size and function were similar between the obesity and type 2 diabetes and control groups by MRI. All patients except four had normal diastolic assessment by echocardiography. In contrast, measures of LA function using magnetic resonance feature tracking were uniformly altered in the obesity and type 2 diabetes group only. Although there was no significant difference in intra-myocardial fat fraction, Dixon 3D epicardial fat volume(EFV) was significantly elevated in the obesity and type 2 diabetes versus control group (135 ± 31 vs. 90 ± 30 mL/m 2 , p < 0.001). There were significant correlations between LA functional indices and both BMI and EFV (p ≤ 0.007).Conclusions: LA MRI-strain may be a sensitive tool for the detection of early diastolic dysfunction in individuals with obesity and type 2 diabetes and correlated with BMI and epicardial fat supporting a possible association between adiposity and LA strain.

Objective: To study spinal cord compressions occurring in Degenerative Cervical Myelopathy (DCM) using a comprehensive biomechanical model defined by actual features observed in patients, in a view to better understand the pathogenesis and further predict patients evolution. Methods: Anatomical MRIs from 20 DCM patients were collected. Compression indices derived from spinal canal and spinal cord were measured at the compression site. Mean values were compared to values reported in literature and to the Spine Model for Safety and Surgery (comprehensive 3D finite element model of the spine), further used for simulations. Based on those results, a 30% reduction in cord cross-sectional area at C5-C6 intervertebral disk was defined as the compression threshold inducing myelopathy. Four main compression patterns were simulated. Median diffuse, median focal and lateral compression types were modelled as a migration of the disk into the spinal canal evenly, at the central line only and laterally, respectively. Circumferential type involved a posterior compression by the ligamentum flavum. All constraints in spinal cord were quantified along inferior-superior axis, along compression development and within atlasdefined spinal cord regions.Results: Regardless of compression types, predominant stress was found along anteroposterior axis but also along inferior-superior axis, attributable to a slight sliding of the disk in that direction because of natural spine anatomical restrictions. Anterior GM and WM regions globally received the highest stress while lateral pathways were the least affected. Compression applied along the complete anterior side of the cord (median diffuse) globally induced the highest constraints. Additional posterior compression by ligamentum flavum (circumferential) might focus constraints in the anterior gray matter region. Along inferior-superior axis, median diffuse and circumferential types showed a peak of constraints at compression site while median focal and lateral types showed lower constraints values but extending further. Conclusion:Median diffuse type would be the most detrimental based on stress amplitude. Anterior regions would be the most at risk, except for circumferential type where posterior regions would be equally affected. Ischemia would be a significant component in addition to applying constraints to explain the pathogenesis of DCM, in particular for lateral pathways. Future work will look at patient-specific simulations and 3/31 relation with clinical symptoms. Biomechanical models could become strong predictors of degenerative changes.

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Purpose To determine whether left atrial (LA) strain quantification with cardiac magnetic resonance (MR) imaging feature tracking is associated with the severity of LA fibrofatty myocardial remodeling at histologic analysis. Materials and Methods This prospective case-control study was approved by the institutional review board. LA strain was evaluated with cardiac MR feature tracking between January 2014 and March 2015 in 13 consecutive patients (mean age, 61 years ± 19; nine male) with mitral regurgitation in the 24 hours before mitral valve surgery and 13 age- and sex-matched healthy control subjects. LA strain parameters were compared first between control subjects and patients and then according to atrial fibrillation and mitral regurgitation status. Associations between LA strain and histology of preoperative biopsies were reported by using receiver operating characteristic curve analysis and Spearman correlation. Results Peak longitudinal atrial strain (PLAS) was significantly lower in patients with mitral regurgitation than in healthy control subjects (P < .001). Increased LA remodeling was significantly related to altered LA strain, and the strongest association was found between PLAS and the degree of fibrofatty myocardial replacement at histologic analysis (r = -0.75, P = .017). LA end-diastolic volume was increased in patients with mitral regurgitation when compared with that in healthy volunteers (P < .001) because of volume overload; however, volume did not correlate with the histologic degree of LA fibrofatty replacement (r = -0.35, P = .330). Conclusion LA strain, especially PLAS, correlates strongly with the degree of fibrofatty replacement at histologic analysis. Such functional imaging biomarker in combination with LA volumetry could help to guide clinical decisions, since myocardial structural remodeling is a known morphologic substrate of LA dysfunction leading to atrial fibrillation with adverse outcome. RSNA, 2017 Online supplemental material is available for this article.

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