Real-Time 3-Dimensional Transesophageal Echocardiography in the Evaluation of Post-Operative Mitral Annuloplasty Ring and Prosthetic Valve Dehiscence

ObjectivesThis study sought to assess the use of real-time (RT) 3-dimensional (3D) transthoracic and transesophageal echocardiography (TEE) in the evaluation of post-operative mitral valve dehiscence.BackgroundMitral valve replacement or repair may be complicated by post-operative dehiscence of the valve or annuloplasty ring resulting in clinically significant mitral regurgitation or hemolysis. Diagnosis is generally performed using 2-dimensional transthoracic echocardiography and TEE. Recently, an RT 3D TEE probe has been developed to produce high-quality real-time images.MethodsWe used RT 3D TEE to evaluate mitral regurgitation after mitral valve repair or replacement as a result of mitral ring dehiscence. We studied the additional information and diagnostic utility provided by RT 3D TEE.ResultsEighteen patients were studied (8 patients after repair and 10 after replacement). Real-time 3D TEE allowed accurate evaluation of the pathology, including definition of the type of ring or prosthesis used; description of the site, size, shape, and area of the dehisced segment; and clear definition of the origin of the mitral regurgitation.ConclusionsIn mitral valve dehiscence, RT 3D TEE provides additional information about the exact anatomic characteristics of the dehiscence that can be used to help in planning the most appropriate corrective intervention

Right ventricular endocardial segmentation in CMR images using a novel inter-modality statistical shape modelling approach

Statistical shape modelling (SSM) approaches have been proposed as a powerful tool to segment the left ventricle in cardiac magnetic resonance (CMR) images. Our aim was to extend this method to segment the RV cavity in CMR images and validate it compared to the conventional gold-standard (GS) manual tracing. A SSM of the RV was built using a database of 4347 intrinsically 3D surfaces, extracted from transthoracic 3D echo cardiographic (3DE) images of 219 retrospective patients. The SSM was then scaled and deformed on the base of some features extracted, with different strategies, from each short-axis plane until a stable condition was reached. The proposed approach, tested on 14 patients, resulted in a high correlation (r2=0.97) and narrow limits of agreement (± 17% error) when comparing the semiautomatic volumes to the GS, confirming the accuracy of this approach in segmenting the RV endocardium

Magnetic and electronic structures of superconducting RuSr2_2GdCu2_2O8_8

The coexistence of ferromagnetism and superconductivity in RuSr$_2$GdCu$_2$O$_8$ was reported both from experiments (by Tallon et. al.) and first-principles calculations (by Pickett et. al.). Here we report that our first-principles full-potential linearized augmented plane wave (FLAPW) calculations, employing the precise crystal structure with structural distortions (i.e., RuO$_6$ rotations) determined by neutron diffraction, demonstrate that antiferromagnetic ordering of the Ru moments is energetically favored over the previously proposed ferromagnetic ordering. Our results are consistent with recently performed magnetic neutron diffraction experiments (Lynn et. al). Ru $t_{2g}$ states, which are responsible for the magnetism, have only a very small interaction with Cu $e_g$ states, which results in a small exchange splitting of these states. The Fermi surface, characterized by strongly hybridized $dp\sigma$ orbitals, has nesting features similar to those in the two-dimensional high $T_c$ cuprate superconductors.Comment: 6 pages,6 figures, accepted for publication in Phys. Rev.

Evaluation of different statistical shape models for segmentation of the left ventricular endocardium from magnetic resonance images

International audienceStatistical shape models (SSMs) represent a powerful tool used in patient-specific modeling to segment medical images because they incorporate a-priori knowledge that guide the model during deformation. Our aim was to evaluate segmentation accuracy in terms of left ventricular (LV) volumes obtained using four different SSMs versus manual gold standard tracing on cardiac magnetic resonance (CMR) images. A database of 3D echocardiographic (3DE) LV surfaces obtained in 435 patients was used to generate four different SSMs, based on cardiac phase selection. Each model was scaled and deformed to detect LV endocardial contours in the enddiastolic (ED) and end-systolic (ES) frames of a CMR short-axis (SAX) stack for 15 patients with normal LV function. Linear correlation and Bland–Altman analyses versus gold-standard showed in all cases high correlation (r²>0.95), non-significant biases and narrow limits of agreement

Imaging and Quantification of Myocardial Perfusion Using Real-Time Three-Dimensional Echocardiography

ObjectivesWe tested the feasibility of real-time three-dimensional echocardiographic (RT3DE) perfusion imaging and developed and validated an algorithm for volumetric analysis of myocardial contrast inflow. The study included three protocols wherein perfusion was measured: 1) in an ex-vivo model of controlled global coronary flow, 2) in an in-vivo model during regional perfusion variations, and 3) in humans during pharmacologically induced hyperemia.BackgroundThe RT3DE technology offers an opportunity for myocardial perfusion imaging without multi-slice reconstruction and repeated contrast maneuvers.MethodsElectrocardiographically triggered harmonic RT3DE datasets were acquired (Philips 7500) while infusion of Definity was initiated and reached a steady state. Protocol 1 was performed in nine isolated rabbit hearts and included three coronary flow levels. In protocol 2, changes in regional perfusion caused by partial left anterior descending artery occlusion were measured in five pigs. In protocol 3, adenosine-induced changes in perfusion were measured in eight normal volunteers. Myocardial video-intensity (MVI) was measured over time in three-dimensional (3D) slices to calculate peak contrast inflow rate (PCIR). In pigs, PCIR was measured on a regional basis and validated against microspheres.ResultsThe RT3DE imaging allowed selection of slices for perfusion analysis in rabbit hearts, pigs, and humans. Administration of contrast resulted in clearly visible and quantifiable changes in MVI. In rabbits, The PCIR progressively decreased with coronary flow (p < 0.0001). In pigs, coronary occlusion caused a 59 ± 26% decrease in PCIR exclusively in the left anterior descending artery territory (p < 0.05) in agreement with microspheres. In humans, adenosine increased PCIR to 198 ± 57% of baseline (p < 0.05).ConclusionsContrast-enhanced RT3DE imaging provides the basis for volumetric imaging and quantification of myocardial perfusion

Live 3-Dimensional Transesophageal Echocardiography Initial Experience Using the Fully-Sampled Matrix Array Probe

ObjectivesOur study goals were to evaluate the 3-dimensional matrix array transesophageal echocardiographic (3D-MTEE) probe by assessing the image quality of native valves and other intracardiac structures.BackgroundBecause 3-dimensional transesophageal echocardiography with gated rotational acquisition is not used routinely as the result of artifacts, lengthy acquisition, and processing, a 3D-MTEE probe was developed (Philips Medical Systems, Andover, Massachusetts).MethodsIn 211 patients, 3D-MTEE zoom images of the mitral valve (MV), aortic valve, tricuspid valve, interatrial septum, and left atrial appendage were obtained, followed by a left ventricular wide-angled acquisition. Images were reviewed and graded off-line (Xcelera with QLAB software, Philips Medical Systems).ResultsExcellent visualization of the MV (85% to 91% for all scallops of both MV leaflets), interatrial septum (84%), left atrial appendage (86%), and left ventricle (77%) was observed. Native aortic and tricuspid valves were optimally visualized only in 18% and 11% of patients, respectively.ConclusionsThe use of 3D-MTEE imaging, which is feasible in most patients, provides superb imaging of native MVs, which makes this modality an excellent choice for MV surgical planning and guidance of percutaneous interventions. Optimal aortic and tricuspid valve imaging will depend on further technological developments. Fast acquisition and immediate online display will facilitate wider acceptance and routine use in clinical practice