Abstract-Heart failure-induced cardiovascular morbidity and mortality constitute a major health problem worldwide and result from diverse pathogeneses, including coronary artery disease, nonischemic cardiomyopathies, and arrhythmias. Assessment of cardiovascular performance is important for early diagnosis and accurate management of patients at risk of heart failure. During the past decade, cardiovascular magnetic resonance myocardial feature tracking has emerged as a useful tool for the quantitative evaluation of cardiovascular function. The method allows quantification of biatrial and biventricular mechanics from measures of deformation: strain, torsion, and dyssynchrony. The purpose of this article is to review the basic principles, clinical applications, accuracy, and reproducibility of cardiovascular magnetic resonance myocardial feature tracking, highlighting the prognostic implications. It will also provide an outlook on how this field might evolve in the future. (Circ Cardiovasc Imaging. 2016;9:e004077.

Background-Cardiac MRI is important in the treatment of children with congenital heart disease, but sufficient normative data are lacking. For ventricular volumes and mass, we sought to deliver reference centiles and to investigate sex effects. Methods and Results-We included 114 healthy children and adolescents, uniformly distributed spanning an age range of 4 to 20 years, as required by the Lambda-Mu-Sigma method to achieve a percentile distribution, thus avoiding arbitrary age categories. Subjects underwent axial volumetry (1.5-T scanner) using standardized 2D steady-state free-precession and flow protocols. Percentiles were computed for age 8 to 20 years (99 subjects) because breath-holds were more consistent in this group. When indexed for body surface area or height, the centile curves of ventricular volumetric parameters showed allometric increase until adolescence, when a plateau was reached, with values comparable to published adult reference data. In contrast, ventricular mass centiles increased without plateau. There was a significant sex difference, with centiles reflecting larger values in boys than in girls (PϽ0.05) when ventricular volumes were indexed to body surface area or height but not when indexed to weight (exception: mass). There was excellent agreement of axial and short-axis volumetry and of volumetric and flow-derived stroke volumes. Conclusions-Percentiles for ventricular volumes and mass in healthy children have been established to serve as reference values in pediatric heart disease. Significant sex differences were noted when indexing volumes to body surface area or height. Unisex centiles related to weight may be considered for chamber volumes albeit not for mass. (Circ Cardiovasc Imaging. 2010;3:65-76.)

Background-Operator-independent isotropic 3D MRI may greatly simplify the assessment of complex morphology in congenital heart disease. We sought to evaluate the reliability of this new approach. Methods and Results-In 31 adolescent and adult patients (age, 6 to 42 years; median, 16 years) with congenital heart disease, cardiac morphology was determined with free-breathing (navigator-gated), isotropic, 3D steady-state freeprecession (3D SSFP) MRI and independently evaluated by 2 observers. Cardiac diagnoses and multiple distance measurements were compared with conventional MR reference sequences (ie, spin-echo, cine gradient-echo, contrastenhanced MR angiography) and with echocardiography/cine cardioangiography or surgery. Of the 31 patients, 24 had native congenital heart defects or residual defects after repair that warranted immediate treatment. None of these defects was missed by 3D SSFP. Novel diagnostic issues were discovered in 4 of 31 patients (coronary anomalies, nϭ3; left juxtaposition of the right atrial appendage in double-outlet right ventricle and transposition of the great arteries, 1). For sizes of valves and vessels, we found minor mean differences of Ϫ1.1 to 1.6 mm, with SD ranging from 1.2 to 2.9 mm, demonstrating overall good agreement with standard MRI (Bland-Altman analysis). Interobserver variability of 3D SSFP distance measures was low; mean differences ranged from Ϫ1.5 to 1.0 mm, and SD ranged from 0.8 to 2.5 mm. Scatter was lower for extracardiac than intracardiac measures. Conclusions-In adolescents and adults, isotropic 3D SSFP MRI allows reliable assessment of complex cardiac morphology. Distance measurements are accurate and reproducible. Thus, a single operator-independent acquisition may substitute for conventional 2D MRI sequences to accelerate and simplify MR scanning in congenital heart disease.

Four-dimensional (4D) flow imaging has been used to study flow patterns and pathophysiology, usually focused on specific thoracic vessels and cardiac chambers. Whole-heart 4D flow at high measurement accuracy covering the entire thoracic cardiovascular system would be desirable to simplify and improve hemodynamic assessment. This has been a challenge because compensation of respiratory motion is difficult to achieve, but it is paramount to limit artifacts and improve accuracy. In this work we propose a self-gating technique for respiratory motion-compensation integrated into a whole-heart 4D flow acquisition that overcomes these challenges. Key words: 4D flow imaging; whole heart; self-gating; Hemodynamic assessment; congenital heart disease Over the past two decades, flow imaging by phase-contrast magnetic resonance imaging (PC-MRI) has become a highly valuable diagnostic method in cardiology, as it allows reliably quantification of blood flow rates and qualitative delineation of flow patterns in the cardiovascular system (1). This is usually performed by the acquisition of a number of two-dimensional (2D) slices with either inplane or through-plane velocity-encoding (VENC). This method is time-consuming and needs careful planning of the various image planes and prior knowledge of both the flow-encoding direction and expected flow velocities (2).Therefore, it usually requires a highly skilled operator, particularly in patients with complicated anatomy such as with congenital heart disease (CHD). It would be much easier to acquire a four-dimensional (4D) MR flow data set covering the entire thoracic cardiovascular system (3). In 4D flow, anatomical and three-directional velocity information are acquired for each pixel within a three dimensional (3D) volume over time (4,5). Flow information can then be analyzed during postprocessing from any reformatted image plane, and prior knowledge of flow directions is not necessary.In the clinical setting, 4D MR flow imaging has mainly been applied to assess flow patterns qualitatively in order to study the pathophysiology of various pathological conditions of the great arteries and cardiac chambers (6 -9), including Fontan-type palliation of complex CHD (10). These studies were usually focused on a particular thoracic vessel or chamber of the heart (11).However, there is much less evidence that 4D flow can reproducibly provide quantitative measures such as stroke volumes (SVs) in various thoracic vessels at a level of accuracy as reached by conventional 2D PC-MR flow. A major concern is potential measurement bias introduced by respiratory motion due to the long acquisition time, constituting the need for effective respiratory motion-compensation strategies. One approach is to obtain multiple signal averages during free-breathing, which has been validated for 2D through-plane flow measurements (2). However, this approach may result in reduced image quality, for which 4D flow is more susceptible than 2D flow as it involves a larger volume and flow directions in three orthogo...