LV Contours Research Articles

Contour-constrained branch U-Net for accurate left ventricular segmentation in echocardiography.

Using echocardiography to assess the left ventricular function is one of the most crucial cardiac examinations in clinical diagnosis, and LV segmentation plays a particularly vital role in medical image processing as many important clinical diagnostic parameters are derived from the segmentation results, such as ejection function. However, echocardiography typically has a lower resolution and contains a significant amount of noise and motion artifacts, making it a challenge to accurate segmentation, especially in the region of the cardiac chamber boundary, which significantly restricts the accurate calculation of subsequent clinical parameters. In this paper, our goal is to achieve accurate LV segmentation through a simplified approach by introducing a branch sub-network into the decoder of the traditional U-Net. Specifically, we employed the LV contour features to supervise the branch decoding process and used a cross attention module to facilitate the interaction relationship between the branch and the original decoding process, thereby improving the segmentation performance in the region LV boundaries. In the experiments, the proposed branch U-Net (BU-Net) demonstrated superior performance on CAMUS and EchoNet-dynamic public echocardiography segmentation datasets in comparison to state-of-the-art segmentation models, without the need for complex residual connections or transformer-based architectures. Our codes are publicly available at Anonymous Github https://anonymous.4open.science/r/Anoymous_two-BFF2/ .

Abstract 17867: Inward Displacement: A Novel CMR Technique for Quantification of Myocardial Wall Motion in Patients With Myocardial Infarction

Introduction: Inward displacement (InD) is a novel parameter which quantifies myocardial wall motion (WM) by measuring the distance travelled by endocardial tracked points towards their corresponding center of the left ventricle in systole, calculated from 3 LAX views obtained during CMR. Hypothesis: InD using CMR is capable of obtaining global quantifiable measurement of WM abnormalities in patients with myocardial infarction (MI) as defined by Late Gadolinium Enhancement (LGE). Methods: We compared patients with history of MI documented by LGE CMR.Studies were acquired in a 1.5 T Siemens Aera (Siemens, Erlangen Germany) scanner with an 18-channel body array coil; Multi-planar ECG-gated cine CMR was obtained using a balanced steady-state free precession readout and LGE images were acquired using an IR prepped sequence 10 min after Gadolinium contrast injection. Offline analysis using automated endocardial LV contour detection was conducted for each of the LAX series and manual corrections were performed as required. InD was measured in mm and expressed as a percentage. Values were compared between MI patients and normal subjects, and analyzed using a Medis Suite workstation (Medis Medical Imaging BV, Leiden, The Netherlands). Results: We analyzed 646 segments in 38 patients of which 9 had past history of myocardial infarction. Global InD for healthy subjects was 28% vs 19% SEM 0.97, as compared to patients with MI (p:< 0.00001). Conclusions: InD is capable of quantification of abnormal motility in subjects with myocardial infarction, therefore producing an objective measure of LV segmental WM abnormalities, further studies are warranted.

Analysis on SPECT myocardial perfusion imaging with a tool derived from dynamic programming to deep learning

Our study tries to propose a method that can rapidly process and calibrate data sets through our previous dynamic programming (DP) tool, manually adjust error-heavy labels, and then train neural network models to accurately segment gated SPECT MPI images. Lastly, LV contours can be accurately determined on the gated SPECT MPI images and corresponding LV volumes can also be evaluated. First, we used our previous DP-based tool to coarsely determine the myocardial profiles on SPECT MPI images. In order to obtain a more accurate LV volumes and LVEF, it was also necessary to manually adjust the profiles that do not meet the clinical requirements. Then the results of manual adjustment were used as the ground truths to train the end-to-end full convolution neural networks by deep learning (DL). The method proposed in this paper was evaluated with the Dice similarity coefficient and Hausdorff distance, and the results showed that the proposed method had a high similarity with the ground truth. The LV volumes and LVEFs estimated by different methods were calculated separately and compared each other, and the experimental results showed that the performance of the proposed DL-based method was superior to that of the DP-based method and close to that of QGS program. As a quantitative analysis tool, the proposed DL-based method is fully automatic and more accurate in the evaluation of LV volumes and LVEFs, so it is expected that the DL-based method may have a wide application prospect in clinical practices.

A New Framework for Performing Cardiac Strain Analysis from Cine MRI Imaging in Mice

Cardiac magnetic resonance (MR) imaging is one of the most rigorous form of imaging to assess cardiac function in vivo. Strain analysis allows comprehensive assessment of diastolic myocardial function, which is not indicated by measuring systolic functional parameters using with a normal cine imaging module. Due to the small heart size in mice, it is not possible to perform proper tagged imaging to assess strain. Here, we developed a novel deep learning approach for automated quantification of strain from cardiac cine MR images. Our framework starts by an accurate localization of the LV blood pool center-point using a fully convolutional neural network (FCN) architecture. Then, a region of interest (ROI) that contains the LV is extracted from all heart sections. The extracted ROIs are used for the segmentation of the LV cavity and myocardium via a novel FCN architecture. For strain analysis, we developed a Laplace-based approach to track the LV wall points by solving the Laplace equation between the LV contours of each two successive image frames over the cardiac cycle. Following tracking, the strain estimation is performed using the Lagrangian-based approach. This new automated system for strain analysis was validated by comparing the outcome of these analysis with the tagged MR images from the same mice. There were no significant differences between the strain data obtained from our algorithm using cine compared to tagged MR imaging. Furthermore, we demonstrated that our new algorithm can determine the strain differences between normal and diseased hearts.

Real-time cardiac magnetic resonance cine imaging with sparse sampling and iterative reconstruction for left-ventricular measures: Comparison with gold-standard segmented steady-state free precession

BackgroundSegmented cine imaging with a steady-state free-precession sequence (Cine-SSFP) is currently the gold standard technique for measuring ventricular volumes and mass, but due to multi breath-hold (BH) requirements, it is prone to misalignment of consecutive slices, time consuming and dependent on respiratory capacity. Real-time cine avoids those limitations, but poor spatial and temporal resolution of conventional sequences has prevented its routine application. We sought to examine the accuracy and feasibility of a newly developed real-time sequence with aggressive under-sampling of k-space using sparse sampling and iterative reconstruction (Cine-RT). MethodsStacks of short-axis cines were acquired covering both ventricles in a 1.5T system using gold standard Cine-SSFP and Cine-RT. Acquisition parameters for Cine-SSFP were: acquisition matrix of 224×196, temporal resolution of 39ms, retrospective gating, with an average of 8 heartbeats per slice and 1–2 slices/BH. For Cine-RT: acquisition matrix of 224×196, sparse sampling net acceleration factor of 11.3, temporal resolution of 41ms, prospective gating, real-time acquisition of 1 heart-beat/slice and all slices in one BH. LV contours were drawn at end diastole and systole to derive LV volumes and mass. ResultsForty-one consecutive patients (15 male; 41±17years) in sinus rhythm were successfully included. All images from Cine-SSFP and Cine-RT were considered to have excellent quality. Cine-RT-derived LV volumes and mass were slightly underestimated but strongly correlated with gold standard Cine-SSFP. Inter- and intra-observer analysis presented similar results between both sequences. ConclusionsCine-RT featuring sparse sampling and iterative reconstruction can achieve spatial and temporal resolution equivalent to Cine-SSFP, providing excellent image quality, with similar precision measurements and highly correlated and only slightly underestimated volume and mass values.

Recommendations for cardiac chamber quantification by echocardiography in adults: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging.

The rapid technological developments of the past decade and the changes in echocardiographic practice brought about by these developments have resulted in the need for updated recommendations to the previously published guidelines for cardiac chamber quantification, which was the goal of the joint writing group assembled by the American Society of Echocardiography and the European Association of Cardiovascular Imaging. This document provides updated normal values for all four cardiac chambers, including three-dimensional echocardiography and myocardial deformation, when possible, on the basis of considerably larger numbers of normal subjects, compiled from multiple databases. In addition, this document attempts to eliminate several minor discrepancies that existed between previously published guidelines.

A LOCALIZED GLOBAL DEFORMATION MODEL TO TRACK MYOCARDIAL MOTION USING ECHOCARDIOGRAPHY

In this paper, we propose a robust real-time myocardial border tracking algorithm for echocardiography. Commonly, after an initial contour of LV border is traced at one or two frame from the entire cardiac cycle, LV contour tracking is performed over the remaining frames. Among a variety of tracking techniques, optical flow method is the most widely used for motion estimation of moving objects. However, when echocardiography data is heavily corrupted in some local regions, the errors bring the tracking point out of the endocardial border, resulting in distorted LV contours. This shape distortion often occurs in practice since the data acquisition is affected by ultrasound artifacts, dropout or shadowing phenomena of cardiac walls. The proposed method deals with this shape distortion problem and reflects the motion realistic LV shape by applying global deformation modeled as affine transform partitively to the contour. We partition the tracking points on the contour into a few groups and determine each affine transform governing the motion of the partitioned contour points. To compute the coefficients of each affine transform, we use the least squares method with equality constraints that are given by the relationship between the coefficients and a few contour points showing good tracking results. Many real experiments show that the proposed method supports better performance than existing methods.

Robust Myocardial Motion Tracking for Echocardiography: Variational Framework Integrating Local-to-Global Deformation

This paper proposes a robust real-time myocardial border tracking algorithm for echocardiography. Commonly, after an initial contour of LV border is traced at one or two frames from the entire cardiac cycle, LV contour tracking is performed over the remaining frames. Among a variety of tracking techniques, optical flow method is the most widely used for motion estimation of moving objects. However, when echocardiography data is heavily corrupted in some local regions, the errors bring the tracking point out of the endocardial border, resulting in distorted LV contours. This shape distortion often occurs in practice since the data acquisition is affected by ultrasound artifacts, dropouts, or shadowing phenomena of cardiac walls. The proposed method is designed to deal with this shape distortion problem by integrating local optical flow motion and global deformation into a variational framework. The proposed descent method controls the individual tracking points to follow the local motions of a specific speckle pattern, while their overall motions are confined to the global motion constraint being approximately an affine transform of the initial tracking points. Many real experiments show that the proposed method achieves better overall performance than conventional methods.

Automated quantitative assessment of myocardial infarction in late enhancement MRI

Methods Twenty patients with known chronic myocardial infarction (all male, mean age 64 ± 8, range 45-82 years) referred for viability assessment were included. LE MR was performed in multiple short axis slices covering the entire LV (slice thickness 10 mm, 5 mm overlap). Endocardial and epicardial LV contours were derived semi-automatically taking into account corresponding cine MR data. Two independent observers manually outlined the MI regions from a total of 348 slices.

Future strategies of reverse remodeling: Summation

Before embarking on any strategy to reverse the hypertrophic and structural response called “remodeling,” we must address the fundamental question as to whether this is good or bad. Although progressive dilatation of a damaged or failing heart has deleterious long-term consequences, it is by no means clear that all features of the underlying process actually harm the patient. The increased ventricular mass, for example, helps to normalize wall stress, and so unloads the cells of an overloaded or damaged ventricle. In addition, several features of the reversion to the fetal phenotype that accompanies remodeling are energy-sparing. An alternative concept is that the “remodeling” response is an indicator of the ability of the myocardium to maintain a long-term altered state in response to stress, and is therefore an indicator only of myocardial damage; hypertrophy and remodeling are therefore harbingers of cell death. Although it might seem paradoxical for a single response to do both good and harm, this apparent contradiction is commonly seen in biology. One example of this dichotomy is the neurohumoral response to the underfilling of the arterial system. Peter Harris, in one of the most important papers on the neurohumoral response written in the 20th century, describes the roles of fluid retention, vasoconstriction, and cardiac stimulation. Harris suggests that all three evolved as short-term responses that are essential during vigorous exercise and aid in survival following hemorrhage. In the latter, fluid retention increases circulating blood volume and so supports cardiac output by maintaining preload. Vasoconstriction raises arterial pressure so as to perfuse the brain and heart, and -adrenergic stimulation helps maintain cardiac output by increasing heart rate and stroke volume. However, when called upon chronically in the patient with heart failure, all of these responses become deleterious and worsen long-term disability. Much of the clinical benefit of diuretics, vasodilators, and beta blockers occurs when these deleterious effects are blocked. This pattern of short-term benefit and long-term harm also characterizes the hypertrophic response of the overloaded heart. The beneficial effect, clearly documented more than 30 years ago, is the normalization of wall stress (see below), while the harm involves the deleterious effects of remodeling, the topic of this meeting. This dichotomy was understood by the great clinical pathologists of the 19th century who, before it was possible to measure the hemodynamic abnormalities in heart failure, examined the architecture of failing hearts in an effort to understand the causes of death and disability in their patients. Initially, these scientists favored the view that hypertrophy and, to a lesser extent, remodeling are advantageous. The term remodeling was first used in relation to myocardial ischemia in 1982 when Hochman and Buckley wrote in the discussion of a paper on ventricular dilatation in rats following coronary occlusion; “If early thinning and dilatation did not occur after myocardial infarction, the process of remodeling with resorbtion of necrotic tissue, laying down of granulation tissue and scar formation would probably result in a healed area that was somewhat thinned but generally preserved normal LV contour.” This term was first applied to changes in myocardium remote from the ischemic area in 1985 in both rats and humans.

Quantification of ventricular performance: a computer-based system for the analysis of angiographic data.

A computer-based quantitative angiography system for the acquisition and analysis of ventriculographic data has been developed. In addition to the apparatus normally required for angiography and left ventricular pressure recording, a digitizing tablet, PDP 11/20 mini computer, and TV monitor with a hard-copy device is employed. Four modes of operation are currently in use: data acquisition, analysis, mini cine, and data tape editor. Data acquisition facilitates forming a magnetic tape record of the digitized pressure, timing, and event identification, together with anywhere from 4 to 100 digitilized LV contours. A number of error checks and feedbacks are incorporated to provide some measure of quality control. In the event an error is written onto the magnetic tape record, the data tape editor can be used to review the record and correct most errors. Analysis of the generated data tape consists of several options which include: pump function, muscle function, pressure derived indices of contractility and systolic time intervals, and contour pattern recognition which is still under development. If the complete analysis option is chosen, a summary of the analysis, referred to as the quick-sight list, is also presented. The so called mini cine option employs a separate and independent acquisition-analysis program. This requires only the end-diastolic (with a segment of wall) and end-systolic contours (without pressure data) to extract the most essential parameters (EDV, EF, CI, HR, and wall mass). As a result of the relative straightforward processing and inherent simplicity, the mini cine option is most frequently used. This system has done much to reduce the time required for analysis of angiographic data, while at the same time maintaining and even improving the quality of the results. Other less tangible benefits include: the possibility to build a readily accessible library of patient data files facilitating a posteriori studies, precise and uniform definition of the rules to input and analyze data, and finally providing a useful step towards fully automatic ventriculographic processing.