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The objective of this review is to provide an overview of the role of cardiac magnetic resonance (CMR) in aortic stenosis (AS). Although CMR is undeniably the gold standard for assessing left ventricular volume, mass, and function, the assessment of the left ventricular repercussions of AS by CMR is not routinely performed in clinical practice, and its role in evaluating and quantifying AS is not yet well established. CMR is an imaging modality integrating myocardial function and disease, which could be particularly useful in a pathology like AS that should be considered as a global myocardial disease rather than an isolated valve disease. In this review, we discuss the emerging potential of CMR for the diagnosis and prognosis of AS. We detail its utility for studying all aspects of AS, including valve anatomy, flow quantification, left ventricular volumes, mass, remodeling, and function, tissue mapping, and 4-dimensional flow magnetic resonance imaging. We also discuss different clinical situations where CMR could be useful in AS, for example, in low-flow low-gradient AS to confirm the low-flow state and to understand the reason for the left ventricular dysfunction or when there is a suspicion of associated cardiac amyloidosis.

Background: In prior work, the authors demonstrated that two-dimensional speckle-tracking (2DST) correlated well but systematically overestimated global longitudinal strain (LS) and circumferential strain (CS) compared with two-dimensional cardiac magnetic resonance tagging (2DTagg) and had poor agreement on a segmental basis. Because three-dimensional speckle-tracking (3DST) has recently emerged as a new, more comprehensive evaluation of myocardial deformation, this study was undertaken to evaluate whether it would compare more favorably with 2DTagg than 2DST., Methods: In a prospective two-center trial, 119 subjects (29 healthy volunteers, 63 patients with left ventricular dysfunction, and 27 patients with left ventricular hypertrophy) underwent 2DST, 3DST, and 2DTagg. Global, regional (basal, mid, and apical), and segmental (18 and 16 segments per patient) LS and CS by 2DST and 3DST were compared with 2DTagg using intraclass correlation coefficients (ICCs) and Bland-Altman analysis. Test-retest reproducibility of 3DST and 2DST was compared in 48 other patients., Results: Both global LS and CS by 3DST agreed better with 2DTagg (ICC = 0.89 and ICC = 0.83, P < .001 for both; bias = 0.5 ± 2.3% and 0.2 ± 3%) than 2DST (ICC = 0.65 and ICC = 0.55, P < .001 for both; bias = -5.5 ± 2.5% and -7 ± 5.3%). Unlike 2DST, 3DST did not overestimate deformation at the regional and particularly the apical levels and at the segmental level had lower bias (LS, 0.8 ± 2.8% vs -5.3 ± 2.4%; CS, -0.01 ± 2.8% vs -7 ± 2.8%, respectively) but similar agreement with 2DST (LS: ICC = 0.58 ± 0.16 vs 0.56 ± 0.12; CS: ICC = 0.58 ± 0.12 vs 0.51 ± 0.1) with 2DTagg. Finally, 3DST had similar global LS, but better global CS test-retest variability than 2DST., Conclusions: Using 2DTagg as reference, 3DST had better agreement and less bias for global and regional LS and CS. At the segmental level, 3DST demonstrated comparable agreement but lower bias versus 2DTagg compared with 2DST. Also, test-retest variability for global CS by 3DST was better than by 2DST. This suggests that 3DST is superior to 2DST for analysis of global and regional myocardial deformation, but further refinement is needed for both 3DST and 2DST at the segmental level., (Copyright © 2018 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.)

Cardiac magnetic resonance (CMR) has emerged as a powerful tool for in vivo assessments of cardiac parameters in experimental animal models of cardiovascular diseases, but its reproducibility in this setting remains poorly explored. To address this issue, we investigated the test-retest reproducibility of preclinical cardiac magnetic resonance imaging (CMR) at 7 Tesla in healthy C57BL/6 mice, including an analysis of the impact of different anesthetic procedures (isoflurane or pentobarbital). We also analyzed the intra-study reproducibility and the intra- and inter-observer post-processing reproducibility of CMR images. Test-retest reproducibility was high for left ventricular parameters, especially with the isoflurane anesthetic procedure, whereas right ventricular parameters and deformation measurements were less reproducible, mainly due to physiological variability. Post-processing reproducibility of CMR images was high both within and between observers. These results highlight that anesthetic procedures might influence CMR test-retest reproducibility, an important ethical consideration for longitudinal studies in rodent models of cardiomyopathy to limit the number of animals used.

Aims: The aim of the study was to assess the early features of diabetic cardiomyopathy using cardiac magnetic resonance within the first week after streptozotocin injection in mice. We focused on the relationship between left ventricular function and hypovolemia markers in diabetic animals compared to a hypovolemic rodent model., Methods and Results: Swiss mice were randomized into control (group C), streptozotocin-induced diabetes (group D) and furosemide-induced hypovolemia (group F) groups. Cardiac magnetic resonance, non-invasive blood pressure, urine volume, plasma markers of dehydration and cardiac histology were assessed in all groups. Mean blood glucose was higher in diabetic animals than in groups C and F (30.5±5.8 compared to 10.4±2.1 and 11.1±2.8 mmol/L, respectively; p<0.01). Diuresis was increased in animals from group D and F compared to C (14650±11499 and 1533±540 compared to 192±111 μL/24 h; p<0.05). End diastolic and end systolic volumes were lower in group D than in group C at week 1 (1.52±0.36 vs. 1.93±0.35 and 0.54±0.22 vs. 0.75±0.18 mL/kg, p<0.05). These left ventricular volume values in group D were comparable to those observed in the acute hypovolemia model (group F). Increased dehydration plasma markers and an absence of obvious intrinsic myocardial damage (evaluated by cardiac magnetic resonance and histology) suggest that a hemodynamic mechanism underlies the very early drop in left ventricular volumes in group D and provides a potential link to hyperglycemic osmotic diuresis., Conclusions: Researchers using cardiac magnetic resonance in hyperglycemic rodent models should be aware of this hemodynamic mechanism, which may partially explain modifications in cardiac parameters in addition to diabetic myocardial damage.

Background: We evaluated gated-SPECT using a Cadmium-Zinc-Telluride (CZT) camera for assessing global and regional left ventricular (LV) function., Methods: A phantom study evaluated the accuracy of wall thickening assessment using systolic count increase on both Anger and CZT (Discovery 530NMc) cameras. The refillable phantom simulated variable myocardial wall thicknesses. The apparent count increase (%CI) was compared to the thickness increase (%Th). CZT gated-SPECT was compared to cardiac magnetic resonance (CMR) in 27 patients. Global and regional LV function (wall thickening and motion) were quantified and compared between SPECT and CMR data., Results: In the phantom study using a 5-mm object, the regression between %CI and %Th was significantly closer to the line of identity (y = x) with the CZT (R (2) = 0.9955) than the Anger (R (2) = 0.9995, P = .03). There was a weaker correlation for larger objects (P = .003). In patients, there was a high concordance between CZT and CMR for ESV, EDV, and LVEF (all CCC >0.80, P < .001). CZT underestimated %CI and wall motion (WM) compared to CMR (P < .001). The agreement to CMR was better for WM than wall thickening., Conclusion: The Discovery 530NMc provided accurate measurements of global LV function but underestimated regional wall thickening, especially in patients with increased wall thickness.

Background: Cardiac magnetic resonance can detect myocardial oedema using myocardial transverse relaxation time (T2)-weighted sequences but quantitative data are lacking in patients evaluated early after acute myocardial infarction., Aim: To assess the spatial distribution of T2 in patients with recent acute myocardial infarction., Methods: Twenty-four consecutive patients (mean age 60+/-11 years) with acute myocardial infarction (anterior, n=12; inferior, n=12) were evaluated prospectively. T2 was determined using a series of breath-hold T2-weighted segmented half-Fourier turbo-spin echo sequences. No-reflow was defined as the association of early hypoenhancement and delayed enhancement in an akinetic region after a bolus injection of DOTA-Gd (0.2 mmol/kg)., Results: No-reflow was present in 13 (54%) patients and absent in 11 (46%) patients. Mean T2 was increased in the infarct region (84.9+/-23.7 ms) compared with in the remote myocardium (62.8+/-10.3 ms, p=0.0001) and in control subjects (55.7+/-4.6 ms, p<0.0001), but also in the remote myocardium compared with control subjects (p<0.02). In patients with no-reflow, T2 was further increased within the infarcted subendocardium compared with in patients without no-reflow (97.9+/-24.8 ms vs 76.3+/-24.7 ms, p<0.03). Peak troponin correlated with T2 (r=0.47, p<0.02) and was higher in patients with no-reflow (297.9+/-249.7 microg/L) than in patients without no-reflow (42.4+/-43.1 microg/L, p=0.003)., Conclusion: T2 was lengthened in both infarcted and remote myocardium and was influenced by the occurrence of no-reflow.

Magnetic resonance imaging (MRI) has become a useful, even essential, examination in recent years, for the exploration of patients with coronary disease. MRI has several different roles, even though it remains insufficiently requested because insufficiently available. Today it is the reference examination for assessing indicators of ventricular function (volume, ejection fraction, ventricular mass); their prognostic value and importance in determining treatment are well recognized. In the postinfarction period, MRI using late enhancement techniques allows a precise analysis of the extent of necrosis, in terms of segments and transmural involvement. MRI is indicated, especially preoperatively, in cases of ventricular remodeling and its consequences (functional impairment, aneurysms, parietal thrombus). MRI with pharmacological stress may also be used as a tool for detecting myocardial ischemia; in this case, perfusion or first-pass sequences should be used. On the other hand, cardiac MRI for morphologic exploration of the coronary network and measurement of stenosis is not yet routine.

Thoracic radiation therapy may result in accelerated atherosclerosis and in late aortic valve stenosis (AS). In this study, we assessed the feasibility of inducing radiation-induced AS using a targeted aortic valve irradiation (10 or 20 Grays) in two groups of C57Bl6/J (WT) and ApoE−/− mice compared to a control (no irradiation). Peak aortic jet velocity was evaluated by echocardiography to characterize AS. T2*-weighted magnetic resonance imaging after injection of MPIO-αVCAM-1 was used to examine aortic inflammation resulting from irradiation. A T2* signal void on valve leaflets and aortic sinus was considered positive. Valve remodeling and mineralization were assessed using von Kossa staining. Finally, the impact of radiation on cell viability and cycle from aortic human valvular interstitial cells (hVICs) was also assessed. The targeted aortic valve irradiation in ApoE−/− mice resulted in an AS characterized by an increase in peak aortic jet velocity associated with valve leaflet and aortic sinus remodeling, including mineralization process, at the 3-month follow-up. There was a linear correlation between histological findings and peak aortic jet velocity (r = 0.57, p < 0.01). In addition, irradiation was associated with aortic root inflammation, evidenced by molecular MR imaging (p < 0.01). No significant effect of radiation exposure was detected on WT animals. Radiation exposure did not affect hVICs viability and cell cycle. We conclude that targeted radiation exposure of the aortic valve in mice results in ApoE−/−, but not in WT, mice in an aortic valve remodeling mimicking the human lesions. This preclinical model could be a useful tool for future assessment of therapeutic interventions. [ABSTRACT FROM AUTHOR]

Background: Left ventricular remodeling (LVR) is common and associated with adverse outcome after ST‐elevation myocardial infarction (STEMI). We aimed to investigate the association between left atrial (LA) mechanical function using speckle tracking imaging and early LVR at follow‐up in STEMI patients. Methods: Baseline 3D thoracic echocardiograms were performed within 48 h following admission and at a median follow‐up of 7 months after STEMI. A > 20% increase in the left ventricular (LV) end‐diastolic volume compared to baseline at follow‐up was defined as LVR. LA global longitudinal strain was evaluated for the reservoir, conduit, and contraction (LASct) phases. Results: A total of 121 patients without clinical heart failure (HF) were prospectively included, between June 2015 and October 2018 (age 58.3 ± 12.5 years, male 98 (81%)). Baseline and follow‐up LV ejection fraction (LVEF) were 46.8% [41.0, 52.9] and 52.1% [45.8, 57.0] respectively (p <.001). Compared to other patients, those with LVR had significantly lower values of LASct at baseline (−7.4% [−10.1, −6.5] vs. −9.9% [−12.8, −8.1], p <.01), both on univariate and baseline LV volumes‐adjusted analyses. Baseline LA strain for reservoir and conduit phases were not associated with significant LVR at follow‐up. Intra‐ and interobserver analysis showed good reproducibility of LA strain. Conclusions: Baseline LASct may help identifying patients without HF after STEMI who are at higher risk of further early LVR and subsequent HF and who may benefit from more intensive management. [ABSTRACT FROM AUTHOR]

Background--Despite widespread use to characterize and refine prognosis, validation data of two-dimensional (2D) speckle tracking (2DST) echocardiography myocardial strain measurement remain scarce. Methods and Results--Global and regional subendocardial peak-systolic Lagrangian longitudinal (LS) and circumferential strain (CS) by 2DST and 2D-tagged (2DTagg) cardiac magnetic resonance imaging were compared against sonomicrometry in a dynamic heart phantom and among each other in 136 patients included prospectively at 2 centers. The ability of regional LS and CS 2DST and 2DTagg to identify late gadolinium enhancement was compared using receiver operating characteristics curves. In vitro, both LS-2DST and 2DTagg highly agreed with sonomicrometry (intraclass correlation coefficient [ICC], 0.89 and ICC, 0.90, both P<0.001 with -3±2.8% and 0.34±4.35% bias, respectively). In patients, both global LS and global CS 2DST agreed well with 2DTagg (ICC, 0.89 and ICC, 0.80; P<0.001); however, they provided systematically greater values (relative bias of -37±27% and -25±37% for global LS and global CS, respectively). On regional basis, however, ICC (from 0.17 to 0.81) and relative bias (from -9 to -98%) between 2DST and 2DTagg varied strongly among segments. Ability to discriminate infarcted versus noninfarcted segments by late gadolinium enhancement was similarly good for regional LS 2DTagg and 2DST (area under the curve, 0.66 versus 0.59; P=0.08), while it was lower for CS 2DST than 2DTagg (area under the curve, 0.61 versus 0.75; P<0.001). Conclusions--The high accuracy against sonomicrometry and good agreement of global LS and global CS by 2DST and 2DTagg confirm the overall validity of 2DST strain measurement. Yet, higher intertechnique segmental variability and lower ability for detecting infarct suggest that 2DST strain estimates may be less performant on regional than on global basis. [ABSTRACT FROM AUTHOR]

Type 2 diabetes mellitus (T2DM) is a well-recognized independent risk factor for heart failure. T2DM is associated with altered cardiac energy metabolism, leading to ectopic lipid accumulation and glucose overload, the exact contribution of these two parameters remaining unclear. To provide new insight into the mechanism driving the development of diabetic cardiomyopathy, we studied a unique model of T2DM: lipodystrophic Bscl2-/- (seipin knockout [SKO]) mice. Echocardiography and cardiac magnetic resonance imaging revealed hypertrophic cardiomyopathy with left ventricular dysfunction in SKO mice, and these two abnormalities were strongly correlated with hyperglycemia. Surprisingly, neither intramyocardial lipid accumulation nor lipotoxic hallmarks were detected in SKO mice. [18F]Fludeoxyglucose positron emission tomography showed increased myocardial glucose uptake. Consistently, the O-GlcNAcylated protein levels were markedly increased in an SKO heart, suggesting a glucose overload. To test this hypothesis, we treated SKO mice with the hypoglycemic sodium-glucose cotransporter 2 (SGLT2) inhibitor dapagliflozin and the insulin sensitizer pioglitazone. Both treatments reduced the O-GlcNAcylated protein levels in SKO mice, and dapagliflozin successfully prevented the development of hypertrophic cardiomyopathy. Our data demonstrate that glucotoxicity by itself can trigger cardiac dysfunction and that a glucose-lowering agent can correct it. This result will contribute to better understanding of the potential cardiovascular benefits of SGLT2 inhibitors. [ABSTRACT FROM AUTHOR]

Purpose: Preclinical imaging of endothelial activation and mineralization using both positron emission tomography (PET) and magnetic resonance (MR) remains scarce. Procedures: A group of uremic ApoE−/− (Ur), non-uremic ApoE−/− (NUr), and control C57Bl/6 J mice (Ctl) were investigated. Mineralization process was assessed using sodium fluoride ([18F]NaF) PET, and MR imaging combined with intravenous injection of MPIO-αVCAM-1 was used to evaluate endothelial activation. Micro- and macrocalcifications were evaluated by flame atomic absorption spectroscopy and von Kossa staining, respectively. Results: Ur mice showed an active and sustained mineralization process compared to Ctl mice (p = 0.002) using [18F]NaF PET imaging. Calcium plasma level was increased in Ur (2.54 ± 0.09 mM, n = 17) compared to NUr and Ctl mice (2.24 ± 0.01, n = 22, and 2.14 ± 0.02, n = 27, respectively; p < 0.0001). Likewise, vascular calcium content was increased in Ur (0.51 ± 0.06 μg Ca2+ per milligram of dry weight aorta, n = 11) compared to NUr (0.27 ± 0.05, n = 9, p = 0.013) and Ctl (0.28 ± 0.05, n = 11, p = 0.014). Ur mice also had a higher inflammatory state using MPIO-αVCAM-1 MR (p global = 0.01, post hoc analysis Ur vs. Ctl p = 0.003) associated with increased VCAM-1 expression (p global = 0.02). Aortic remodeling at the level of the brachiocephalic trunk, brachiocephalic trunk itself, and aortic arch in Ur mice was also demonstrated using MR. Conclusions: Preclinical molecular imaging allowed in vivo characterization of the early phase of atherosclerosis. [18F]NaF PET showed early and sustained vascular mineralization in uremic ApoE−/− mice. MPIO-αVCAM-1 MR imaging demonstrated aortic endothelial activation, predominantly in segments with vascular remodeling. [ABSTRACT FROM AUTHOR]

This paper presents a novel algorithm that extends HARP to handle 3D tagged MRI images. HARP results were regularized by an original regularization framework defined in an anatomical space of coordinates. In the meantime, myocardium incompressibility was integrated in order to correct the radial strain which is reported to be more challenging to recover. Both the tracking and regularization of LV displacements were done on a volumetric mesh to be computationally efficient. Also, a window-weighted regression method was extended to cardiac motion tracking which helps maintain a low complexity even at finer scales. On healthy volunteers, the tracking accuracy was found to be as accurate as the best candidates of a recent benchmark. Strain accuracy was evaluated on synthetic data, showing low bias and strain errors under 5% (excluding outliers) for longitudinal and circumferential strains, while the second and third quartiles of the radial strain errors are in the ( − 5 % , 5 % ) range. In clinical data, strain dispersion was shown to correlate with the extent of transmural fibrosis. Also, reduced deformation values were found inside infarcted segments. [ABSTRACT FROM AUTHOR]