Patient-Specific Mitral Valve Closure Prediction Using 3D Echocardiography

This article presents an approach to modeling the closure of the mitral valve using patient-specific anatomical information derived from 3D transesophageal echocardiography (TEE). Our approach uses physics-based modeling to solve for the stationary configuration of the closed valve structure from the patient-specific open valve structure, which is recovered using a user-in-the-loop, thin-tissue detector segmentation. The method uses a tensile shape-finding approach based on energy minimization. This method is employed to predict the aptitude of the mitral valve leaflets to coapt. We tested the method using 10 intraoperative 3D TEE sequences by comparing the closed valve configuration predicted from the segmented open valve with the segmented closed valve, taken as ground truth. Experiments show promising results, with prediction errors on par with 3D TEE resolution and with good potential for applications in pre-operative planning.     

Towards patient-specific modeling of mitral valve repair: 3D transesophageal echocardiography-derived parameter estimation

Transesophageal echocardiography (TEE) is routinely used to provide important qualitative and quantitative information regarding mitral regurgitation. Contemporary planning of surgical mitral valve repair, however, still relies heavily upon subjective predictions based on experience and intuition. While patient-specific mitral valve modeling holds promise, its effectiveness is limited by assumptions that must be made about constitutive material properties. In this paper, we propose and develop a semi-automated framework that combines machine learning image analysis with geometrical and biomechanical models to build a patient-specific mitral valve representation that incorporates image-derived material properties. We use our computational framework, along with 3D TEE images of the open and closed mitral valve, to estimate values for chordae rest lengths and leaflet material properties. These parameters are initialized using generic values and optimized to match the visualized deformation of mitral valve geometry between the open and closed states. Optimization is achieved by minimizing the summed Euclidean distances between the estimated and image-derived closed mitral valve geometry. The spatially varying material parameters of the mitral leaflets are estimated using an extended Kalman filter to take advantage of the temporal information available from TEE. This semi-automated and patient-specific modeling framework was tested on 15 TEE image acquisitions from 14 patients. Simulated mitral valve closures yielded average errors (measured by point-to-point Euclidean distances) of 1.86 ± 1.24 mm. The estimated material parameters suggest that the anterior leaflet is stiffer than the posterior leaflet and that these properties vary between individuals, consistent with experimental observations described in the literature.     

Obstructed bi‐leaflet prosthetic mitral valve imaging with real‐time three‐dimensional transesophageal echocardiography

Real‐time three‐dimensional transesophageal echocardiography (RT3D‐TEE) can provide unique visualization and better understanding of the relationship among cardiac structures. Here, we report the case of an 85‐year‐old woman with an obstructed mitral prosthetic valve diagnosed promptly by RT3D‐TEE, which clearly showed a leaflet stuck in the closed position. The opening and closing angles of the valve leaflets measured by RT3D‐TEE were compatible with those measured by fluoroscopy. Moreover, RT3D‐TEE revealed, in the ring of the prosthetic valve, thrombi that were not visible on fluoroscopy. RT3D‐TEE might be a valuable diagnostic technique for prosthetic mitral valve thrombosis. © 2014 Wiley Periodicals, Inc. J Clin Ultrasound 43 :64–67, 2015     

Semi-automated Segmentation and Quantification of Mitral Annulus and Leaflets from Transesophageal 3-D Echocardiographic Images

Quantification of three-dimensional (3-D) morphology of the mitral valve (MV) using real-time 3-D transesophageal echocardiography (RT3-D TEE) has proved to be a valuable tool for the assessment of MV pathologies, but of limited use in clinical practice because it relies on user-intensive approaches. This study presents a new algorithm for the segmentation and morphologic quantification of the mitral annulus (MA) and mitral leaflets (ML) in closed valve configuration from RT3-D TEE volumes. Following initialization, the MA and the ML and the coaptation line (CL) are automatically obtained in 3-D. Validation with manual tracings was performed on 33 patients, resulting in segmentation errors in the order of 0.7 mm and 0.6 mm for the MA and ML segmentation, in addition to good intra- and inter-observer reproducibility (coefficients of variation below 12% and 15%, respectively). The ability of the algorithm to assess different MV pathologies as well as repaired valves with implanted annular rings was also explored. The reported performance of the proposed fast, semi-automated MA and ML quantification makes it promising for future applications in clinical settings such as the operating room, where obtaining results in short time is important.     

Feasibility of measurements of valve dimensions in en-face-3D transesophageal echocardiography

Newest 3D software allows measurements directly in the en-face-3D TEE mode. Aim of the study was to ascertain whether measurements performed in the en-face-3D TEE mode are comparable with conventional measurement methods based on 2D TEE and 3D using the multiple plane reconstruction mode with the Qlab^® software. En-face-3D TEE is used more frequently in daily clinical routine during cardiac operations. So far measurements could only be done based on 2D images or with the use of multi planar reconstruction mode with additional software. Measurement directly in the 3D image (en-face-3D TEE) would make measurements faster and easier to use in clinical practice. After approval by the local ethic committee and written informed consent from the patients additionally to a comprehensive perioperative 2D TEE examination a real time (RT) 3D zoom- dataset was recorded. Routine measurements of the length of anterior and posterior mitral valve leaflets as well as mitral valve and aortic valve areas were performed in en-face-3D TEE, multiplanar reconstruction mode using Qlab^®-software (Philips, Netherlands) and 2D TEE standard views. Twenty nine patients with a mean age of 67 years undergoing elective cardiac surgery/interventions were enrolled in this study. Direct measurements in en-face-3D TEE mode lead to non significant underestimation of all parameters as compared to Qlab^® and 2D TEE measurements. Measurements in en-face-3D TEE are feasible but lead to non significant underestimation compared to measurements performed with Qlab^® or in 2D TEE views.     

Real-time three-dimensional echocardiographic evaluation of the mitral valve

The three-dimensional (3D) echocardiographic system allows us to visually understand the configuration of the complex mitral valve morphology, which consists of the saddle-shaped annulus, leaflets, chordae, and papillary muscles. The recent development of transesophageal real-time 3D echocardiography has led to important advances in the diagnosis of mitral valve disease. Furthermore, the reconstructed 3D images can be quantitatively measured and analyzed in 3D spaces. These observations provide us important additional information in the clinical diagnosis of mitral valve diseases.     

Quantification of mitral valve stenosis by three-dimensional transesophageal echocardiography

The aim of this study was the evaluation of the diagnostic potentials of transesophageal 3D-echocardiography in the determination of mitral valve stenosis. 54 patients were investigated by transthoracic and multiplane transesophageal echocardiography. In 41 patients cardiac catheterization was performed. 3D-echocardiographic data acquisition was performed by automatic transducer rotation at 2° increments over a span of 180°. The transesophageal probe was linked to an ultrasound unit and to a 3D-workstation capable of ECG- and respiration gated data acquisition, postprocessing and 2D/ 3D image reconstruction. The mitral valve was visualized in sequential cross-sectional planes out of the 3D data set. The spatial position of the planes was indicated in a reference image. In the cross-sectional plane with the narrowest part of the leaflets the orifice area was measured by planimetry. For topographic information a 3D view down from the top of the left atrium was reconstructed. Measurements were compared to conventional transthoracic planimetry, to Doppler-echocardiographic pressure half time and to invasive data. The mean difference to transthoracic planimetry, pressure half time and to invasive measurements were 0.3 ± 0.1 cm², 0.2 ± 0.1 cm² and 0.1 ± 0.1 cm², respectively. Remarkable differences between the 3D- echocardiographic and the 2D- or Doppler- echocardiographic methods were observed in patients with severe calcification or aortic regurgitation. In 22% of the patients the 3D data set was not of diagnostic quality. New diagnostic information from a 3D view of the mitral valve could be obtained in 69% of the patients. Thus, although image quality is limited, 3D- echocardiography provides new topographic information in mitral valve stenosis. It allows the use of a new quantitative method, by which image plane positioning errors and flow-dependent calculation is avoided.     

动态三维超声心动图对正常和病变二尖瓣器的临床研究

目的探讨动态三维超声心动图对二尖瓣器评分的价值。方法通过多平面经食管三维超声心动图容积提取显示法（３ＤＶ）对２０例正常二尖瓣、８例二尖瓣狭窄、１２例二尖瓣关闭不全和１０例二尖瓣位人工机械瓣患者的二尖瓣器进行了评分,并与取自三维数据集的任意切面超声心动图（ＡＰＥ）和多平面经食管二维超声心动图（ＴＥＥ）对照。结果３ＤＶ对正常和病变二尖瓣的活动度、连合部、瓣口面积和与毗邻结构的空间关系的评分显著高于ＴＥＥ和ＡＰＥ（Ｐ＜０．０１和Ｐ＜０．０５）。３ＤＶ对病变二尖瓣的诊断价值更优于正常二尖瓣。它对瓣叶厚度、瓣环和瓣下结构的评分低于ＴＥＥ和ＡＰＥ（Ｐ＜０．０１）。三种检查方法对二尖瓣位人工机械瓣的评分无显著性差异（Ｐ＞０．０５）。结论３ＤＶ对评价正常和病变二尖瓣器提供了一种有特殊价值的新方法。     

Extraction of open-state mitral valve geometry from CT volumes

Purpose

The importance of mitral valve therapies is rising due to an aging population. Visualization and quantification of the valve anatomy from image acquisitions is an essential component of surgical and interventional planning. The segmentation of the mitral valve from computed tomography (CT) acquisitions is challenging due to high variation in appearance and visibility across subjects. We present a novel semi-automatic approach to segment the open-state valve in 3D CT volumes that combines user-defined landmarks to an initial valve model which is automatically adapted to the image information, even if the image data provide only partial visibility of the valve.

Methods

Context information and automatic view initialization are derived from segmentation of the left heart lumina, which incorporates topological, shape and regional information. The valve model is initialized with user-defined landmarks in views generated from the context segmentation and then adapted to the image data in an active surface approach guided by landmarks derived from sheetness analysis. The resulting model is refined by user landmarks.

Results

For evaluation, three clinicians segmented the open valve in 10 CT volumes of patients with mitral valve insufficiency. Despite notable differences in landmark definition, the resulting valve meshes were overall similar in appearance, with a mean surface distance of \(1.62 \pm 2.10\) mm. Each volume could be segmented in 5–22 min.

Conclusions

Our approach enables an expert user to easily segment the open mitral valve in CT data, even when image noise or low contrast limits the visibility of the valve.

     

实时三维超声心动图二尖瓣定量分析的临床应用

随着实时三维超声心动图在图像采集、存储及分析等方面技术的逐步提高,尤其是经食管实时三维超声心动图的开发,大幅度改进了心脏动态三维图像的质量,其基础研究及临床应用日渐广泛,最新研究拓展到复杂的二尖瓣装置。本文综述了二尖瓣装置的动态三维成像及其定量分析的研究进展,包括二尖瓣环径线及构型、二尖瓣叶角度及面积、乳头肌牵张长度、二尖瓣对合面积及对合指数等在不同二尖瓣疾病中的病理生理改变,有助于进一步深化临床对二尖瓣装置功能的理角年,增进临床对二尖瓣疾病的认识与处理。     

The technique of transesophageal echocardiography. How to procure detailed views of an array of cardiac structures

Use of transesophageal echocardiography (TEE) is growing in ambulatory, intensive care, and intraoperative settings. Forward flexion or retroflexion of the TEE probe tip at different levels in the esophagus reveals a variety of intracardiac structures; in the basal short-axis view, for example, the aortic valve can be seen, as can the left atrial appendage lateral to the aorta and pulmonary artery. In the four-chamber view, the mitral and tricuspid valves and interatrial septum can be viewed, and the morphology of the mitral valve leaflets and mitral annulus can be assessed. Cross-sectional views of both ventricles can be obtained in the transgastric short-axis view. In addition, the entire thoracic aorta, as well as the proximal ascending and transverse arch, can be visualized with TEE.     

实时三维经食管超声心动图在二尖瓣成形术中的应用研究

目的 探讨术中实时三维经食管超声心动图(RT-3D TEE)判断二尖瓣病变区域的准确性,以及评价二尖瓣成形术效果的价值.方法 19例因二尖瓣反流(MR)拟接受二尖瓣成形术患者,采集术前、术后RT-3D TEE图像,将术前所见与术中发现进行比较,并在术后即刻评价手术疗效.结果 RT-3DTEE诊断二尖瓣叶病变与术中发现完全相符16例,3例不符合,其中1例术前诊断前叶中间段、后叶中间段脱垂,术中仅发现瓣环扩大,瓣膜黏液退行性变;1例术前诊断后叶后内段脱垂,术中发现后叶中间段及后内段腱索断裂;1例术前提示瓣环扩大,术中发现后叶中间段脱垂.2D TEE诊断二尖瓣病变与术中发现完全相符仅10例,且对二尖瓣脱垂患者难以明确脱垂的确切瓣区和范围.术后即刻观察成形术效果,其中18例RT-3DTEE显示微量至少量二尖瓣反流,1例术后仍为中重度反流,改行二尖瓣置换术,二尖瓣成形术的成功率为94.7%.结论 RT-3D TEE明显提高了二尖瓣反流病因及病变部位定位的诊断准确性,在二尖瓣成形术手术方案制定及疗效的即刻评估方面发挥了非常重要的作用.     

三维经食管超声心动图对正常二尖瓣结构参数及其随心动周期变化规律的初步研究

目的：应用经食管三维超声的二尖瓣定量技术分析心内结构、功能正常的二尖瓣结构参数的范围并总结其随心动周期的变化规律，以期为评估二尖瓣病变提供理论基础。 方法：收集37例心内结构、功能正常的二尖瓣食管中段2D及实时三维全容积成像，完整包括二尖瓣及主动脉瓣结构。存取动态图像后记录舒张早、中、晚期及收缩早、中、晚期共6个时相内瓣环前后径、左右径、内纤维三角、瓣叶交界距离等18个二尖瓣结构的数据，总结其参考值范围并分析其运动规律。 结果：总结出该37例研究对象二尖瓣瓣环结构的参考值范围，并发现其随心动周期呈规律性变化：瓣环前后径及左右径，瓣环面积，瓣环周长，前、后瓣环长度，内纤维三角距离，瓣叶交界距离，这些参数的最大值出现在舒张期，最小值出现在收缩期。瓣环高度，瓣环高度/左右径，非平面角度，AO-MV瓣环夹角，AO-MV中点距离，它们的最大值出现在收缩期，最小值出现在舒张期。与前面的结构不同，瓣叶3个分区的Tenting高度及Tenting面积的最大值和最小值分别出现在收缩期早期及晚期。 结论：经食管三维超声的自动定量分析系统能较为快速、直观的重建二尖瓣模型，自动测量多项结构参数。本研究通过分析各参数的最大值、最小值出现的时相，有助于加深理解二尖瓣结构的运动规律，所总结出的参考值范围对于判断二尖瓣病变提供了理论参考，为进一步研究二尖瓣病变结构的变化奠定基础。     

二尖瓣狭窄的四维超声显示

为了显示狭窄二尖瓣的动态立体结构，我们对１０例正常人，２６例二尖瓣狭窄病人进行了四维超声心动图重建研究，建立了二尖瓣的长细，短轴立体剖面图，可分别从侧面，左房面，左室面观察二尖瓣的形态结构及活动状况，结果表明，二尖瓣的四维重建能更直观地显示瓣膜的解剖结构，综合评估狭窄二尖瓣的病变程度。     

经食管实时三维超声心动图对二尖瓣立体结构的定量研究

目的 探讨经食管实时三维超声心动图二尖瓣立体结构定量分析(MVQ)软件的临床价值,筛选出对诊断二尖瓣脱垂和分析二尖瓣反流机制有意义的参数.方法 对18例无二尖瓣反流、瓣膜结构功能正常患者(对照组)和13例二尖瓣脱垂引起大量二尖瓣反流患者(脱垂组),分别行经食管实时三维超声检查,应用MVQ进行后处理,测量收缩期关于二尖瓣立体结构的18个参数.统计两组中有统计学意义的参数.结果 脱垂组的二尖瓣瓣环参数均较对照组增大,差异有统计学意义(P＜0.05).瓣叶的参数关闭时前叶瓣体与瓣环最高平面的夹角(θant)、关闭时后叶瓣体与瓣环最高平面的夹角(θpost)、关闭时前叶与后叶瓣体对合时形成的夹角(θNPA)、瓣叶关闭时穹隆高度(Htent)、瓣叶穹隆的容积(Vtent)、前后叶关闭时对合线的长度(L2DALPm)、主动脉瓣环与二尖瓣环平面夹角(OAv-Mv)两组间比较差异无统计学意义(P＞0.05).前叶自瓣根至对合线的长度(L3Dant)、后叶从瓣根至对合线的长度(L3Dpost)、脱垂瓣叶向左房侧隆起的高度(Hprol)、脱垂部分的容积(Vprol)、后叶瓣体的面积(A3Dpost)、前叶瓣体的面积(A3Dant)脱垂组均大于对照组,差异有统计学意义(P＜0.05).结论 MVQ分析软件可以定量测量二尖瓣的立体结构,使超声心动图对瓣膜病变的诊断更加详细量化,对外科制定精确的手术方案具有重要的指导意义.     

Novel Aspects of 3D Echocardiography in Percutaneous Mitral Valve Interventions: Update 2013

The rapidly increasing importance of percutaneous treatment options for mitral valve diseases promotes the demand for reliable periprocedural guidance by transesophageal echocardiographic imaging. For several interventional mitral leaflet repair techniques real-time 3-dimensional transesophageal echocardiographic (RT3D TEE) guidance has been described to be indispensible. RT3DE TEE provides excellent insight into the mitral valve pathology, which improves procedure planning, safe guidance of device navigation and direct assessment of procedural success. For balloon mitral valvuloplasty 3D echocardiography has shown to effectively accelerate the procedure. The complexity of transcatheter mitral valve repair as well as transcatheter closure of paravalvular leakages of mitral valve prosthesis demands accurate evaluation of the target lesion and guidance of the navigation of the device catheter. All these features have recently found to be uniquely provided by three-dimensional echocardiography. The benefits of RT3D TEE led to its recommendation for percutaneous mitral valve repair procedures in current guidelines. This review of recent literature reports current applications and requirements for refinements in using 3D imaging modalities.     

Advances in 3D echocardiography for mitral valve

The advent of real-time (RT) 3D transesophageal echocardiography (TEE) in 2007 has enhanced our understanding of the location and extent of the pathology of the native, as well as prosthetic, mitral valve (MV), particularly for MV prolapse and the anatomy of perivalvular dehiscence with prosthetic MV. MV quantification programs provide precise assessment of many quantitative MV parameters allowing 3D echocardiography to determine and quantify the geometry of mitral apparatus, including mitral annulus and periannular region, leaflet volume and anatomy, tethering distances, and tenting volumes. The detailed, accurate and optimal RT spatial visualization of the MV with 3D TEE gives greater confidence to the echocardiographer, interventionalist and the surgeon alike, facilitating medical and surgical treatment decisions. This article highlights recent advances in RT 3D TEE and transthoracic echocardiography echocardiographic imaging of the MV.     

Advances in 3D echocardiography for mitral valve

The advent of real-time (RT) 3D transesophageal echocardiography (TEE) in 2007 has enhanced our understanding of the location and extent of the pathology of the native, as well as prosthetic, mitral valve (MV), particularly for MV prolapse and the anatomy of perivalvular dehiscence with prosthetic MV. MV quantification programs provide precise assessment of many quantitative MV parameters allowing 3D echocardiography to determine and quantify the geometry of mitral apparatus, including mitral annulus and periannular region, leaflet volume and anatomy, tethering distances, and tenting volumes. The detailed, accurate and optimal RT spatial visualization of the MV with 3D TEE gives greater confidence to the echocardiographer, interventionalist and the surgeon alike, facilitating medical and surgical treatment decisions. This article highlights recent advances in RT 3D TEE and transthoracic echocardiography echocardiographic imaging of the MV.     

Analysis of circumflex artery anatomy by real time 3D transesophageal echocardiography compared to cardiac computed tomography

Iatrogenic injury to the circumflex artery (Cx) due to its close proximity to the mitral annulus is a rare but dreadful complication that can occur during mitral valve repair. The aim of our study was to compare multiple measurements of the Cx datasets, obtained by real time three-dimensional transesophageal echocardiography (RT3D TEE) and corresponding measurements assessed in multi-planar three-dimensional images acquired by multidetector computed tomography (MDCT). Preoperative RT3D TEE and MDCT datasets of 25 patients who had previously undergone minimally invasive mitral valve surgery were retrospectively analyzed. The vessel diameter and the horizontal as well as vertical distances from the center of the Cx to the mitral valve annulus were measured. Horizontal as well as vertical Cx distances showed a strong correlation between measurements of RT3D TEE and MDCT whereas the measurements of the Cx diameter showed no correlation. Measurements of horizontal and vertical distances of the Cx to the mitral annulus can be performed using RT3D TEE and show good correlation with MDCT-based measurements.