Rapid and accurate left ventricular surface generation from three-dimensional echocardiography by a catalog based method. Rapid LV surface generation by three-dimensional echo

The Lifelong Impact of Artificial Intelligence and Clinical Prediction Models on Patients With Tetralogy of Fallot

Medical advancements in the diagnosis, surgical techniques, perioperative care, and continued care throughout childhood have transformed the outlook for individuals with tetralogy of Fallot (TOF), improving survival and shifting the perspective towards lifelong care. However, with a growing population of survivors, longstanding challenges have been accentuated, and new challenges have surfaced, necessitating a re-evaluation of TOF care. Availability of prenatal diagnostics, insufficient information from traditional imaging techniques, previously unforeseen medical complications, and debates surrounding optimal timing and indications for reintervention are among the emerging issues. To address these challenges, the integration of artificial intelligence and machine learning holds great promise as they have the potential to revolutionize patient management and positively impact lifelong outcomes for individuals with TOF. Innovative applications of artificial intelligence and machine learning have spanned across multiple domains of TOF care, including screening and diagnosis, automated image processing and interpretation, clinical risk stratification, and planning and performing cardiac interventions. By embracing these advancements and incorporating them into routine clinical practice, personalized medicine could be delivered, leading to the best possible outcomes for patients. In this review, we provide an overview of these evolving applications and emphasize the challenges, limitations, and future potential for integrating them into clinical care.

The right ventricle under pressure: evaluating the adaptive and maladaptive changes in the right ventricle in pulmonary arterial hypertension using echocardiography (2013 Grover Conference series)

The importance of the right ventricle (RV) in pulmonary arterial hypertension (PAH) has been gaining increased recognition. This has included a reconceptualization of the RV as part of an RV-pulmonary circulation interrelated unit and the observation that RV function is a major determinant of prognosis in PAH. Noninvasive imaging of RV size and function is critical to the longitudinal management of patients with PAH, and continued understanding of the pathophysiology of pulmonary vascular disease relies on the response of the RV to pulmonary vascular remodeling. Echocardiography, in particular the newer echocardiographic measurements and techniques, allows easy, readily accessible means to assess and follow RV size and function.

Accuracy and Test-Retest Reproducibility of Two-Dimensional Knowledge-Based Volumetric Reconstruction of the Right Ventricle in Pulmonary Hypertension

Background

Right heart function is the key determinant of symptoms and prognosis in pulmonary hypertension (PH), but the right ventricle has a complex geometry that is challenging to quantify by two-dimensional (2D) echocardiography. A novel 2D echocardiographic technique for right ventricular (RV) quantitation involves knowledge-based reconstruction (KBR), a hybrid of 2D echocardiography–acquired coordinates localized in three-dimensional space and connected by reference to a disease-specific RV shape library. The aim of this study was to determine the accuracy of 2D KBR against cardiac magnetic resonance imaging in PH and the test-retest reproducibility of both conventional 2D echocardiographic RV fractional area change (FAC) and 2D KBR.

Methods

Twenty-eight patients with PH underwent same-day echocardiography and cardiac magnetic resonance imaging. Two operators performed serial RV FAC and 2D KBR acquisition and postprocessing to assess inter- and intraobserver test-retest reproducibility.

Results

Bland-Altman analysis (mean bias ± 95% limits of agreement) showed good agreement for end-diastolic volume (3.5 ± 25.0 mL), end-systolic volume (0.9 ± 19.9 mL), stroke volume (2.6 ± 23.1 mL), and ejection fraction (0.4 ± 10.2%) measured by 2D KBR and cardiac magnetic resonance imaging. There were no significant interobserver or intraobserver test-retest differences for 2D KBR RV metrics, with acceptable limits of agreement (interobserver end-diastolic volume, −0.9 ± 21.8 mL; end-systolic volume, −1.3 ± 25.8 mL; stroke volume, −0.2 ± 24.2 mL; ejection fraction, 0.7 ± 14.4%). Significant test-retest variability was observed for 2D echocardiographic RV areas and FAC.

Conclusions

Two-dimensional KBR is an accurate, novel technique for RV volumetric quantification in PH, with superior test-retest reproducibility compared with conventional 2D echocardiographic RV FAC.

Three-dimensional modeling of the right ventricle from two-dimensional transthoracic echocardiographic images: utility of knowledge-based reconstruction in pulmonary arterial hypertension

BACKGROUND

Right ventricular (RV) volume and functional assessments are essential in the management of pulmonary arterial hypertension but are often difficult to perform. Three-dimensional (3D) echocardiography is limited by acoustic dropout of the RV free wall in dilated ventricles. The aim of this study was to test the hypothesis that knowledge-based reconstruction, a novel method for 3D modeling of RV endocardium from two-dimensional echocardiographic images, could provide accurate measurements of RV volumes and systolic function.

METHODS

Twenty-seven patients with pulmonary arterial hypertension were prospectively recruited for same-day echocardiography and cardiovascular magnetic resonance (CMR), which was used as a reference standard. Two-dimensional transthoracic echocardiographic images were acquired with 3D spatial localization equipment to allow 3D reconstruction. Image analysis was performed with dedicated software to obtain end-diastolic volume (EDV) and end-systolic volume (ESV) and RV ejection fraction (EF). The method of disks was used to determine RV volumes on CMR.

RESULTS

Echocardiographic RV volumes correlated well with CMR (EDV, R = 0.87; ESV, R = 0.88; EF, R = 0.75). For interobserver analyses, coefficients of variability were 7.8 ± 7.0% for EDV, 10.2 ± 8.0% for ESV, and 15.4 ± 13.8% for EF. For intraobserver analyses, coefficients of variability were 7.1 ± 5.1% for EDV, 8.3 ± 7.0% for ESV, and 10.9 ± 9.2% for EF. On Bland-Altman analyses, volumes obtained on transthoracic echocardiography (TTE) were slightly larger than those obtained by CMR (ΔEDVTTE-CMR, 5.8 ± 33.7 mL; ΔESVTTE-CMR, 3.5 ± 27.8 mL), whereas EFs tended to be slightly higher by CMR (ΔEFCMR-TTE, 0.5 ± 6.5%).

CONCLUSIONS

Knowledge-based reconstruction provides accurate and reproducible measurements of RV volumes in patients with pulmonary arterial hypertension. Larger studies are needed to confirm these results and to determine the practicality of this approach in daily practice and as an end point in clinical trials.

Accuracy of knowledge-based reconstruction for measurement of right ventricular volume and function in patients with tetralogy of Fallot

We tested the accuracy and reproducibility of knowledge-based reconstruction (KBR) for measuring right ventricular (RV) volume and function. KBR enables rapid assessment of the right ventricle from sparse user input by referencing a database. KBR generates a 3-dimensional surface to fit points that the user enters at anatomic landmarks. We measured the RV volume using KBR from magnetic resonance images in 20 patients with repaired tetralogy of Fallot at end-diastole and end-systole. We entered points in the long- and short-axis and/or oblique views. The true volume was computed by manually tracing the RV borders for 3-dimensional reconstruction using the piecewise smooth subdivision surface method. The reference database included 54 patients with tetralogy of Fallot patients. The KBR values agreed closely with the true values for the end-diastolic volume (r = 0.993), end-systolic volume (r = 0.992), and ejection fraction (EF; r = 0.930). KBR slightly overestimated the end-diastolic volume (4 +/- 10 ml, p = NS), end-systolic volume (1 +/- 9 ml, p = NS), and EF (4 +/- 3%, p = NS). No bias in the error was found by Bland-Altman analysis (p = NS for end-diastolic and end-systolic volume and EF). The KBR volumes had approached the true volumes (235 +/- 93 vs 243 +/- 93, p = 0.012, r = 0.978 for end-diastolic and end-systolic volumes combined) already after the first run and the entry of 19 +/- 3 points. In conclusion, KBR provided accurate measurement of the RV volume and EF with minimal user input. KBR is a clinically feasible alternative to full manual tracing of the heart borders from imaging data.

Expert visual guidance of ultrasound for telemedicine

Expert visual guidance (EVG) is computer assistance that displays to the examiner how the image plane moves towards (or away from) a desired anatomical location as the ultrasound probe is manipulated over the patient's body. We tested whether EVG by a remote expert could assist inexperienced examiners in acquiring abdominal ultrasound images. The inexperienced examiners were 20 medical students, who were randomly assigned to verbal instruction alone (Group 1) or to EVG (Group 2). The examiners were tested on their ability to visualize the abdominal aorta and the right kidney. Group 2 was more successful in identifying specified anatomy in longitudinal and cross-sectional views of the aorta (95 vs. 75%, P = 0.032) and kidney (98 vs. 88%, P = 0.09). The groups succeeded equally well in obtaining a true cross-sectional view of the aorta. Kidney length was also similar when measured by the two groups. The results demonstrate that an inexperienced ultrasonographer can be significantly assisted by EVG compared to verbal instruction alone. This could be useful for tele-mentoring in rural hospitals as well as for teaching, both in person and at a remote site.

Three-dimensional shape analysis of right ventricular remodeling in repaired tetralogy of Fallot

Understanding of right ventricular (RV) remodeling is needed to elucidate the mechanism of RV dysfunction in the overloaded right ventricle, but is hampered by the chamber's complex shape. We imaged 15 patients with repaired tetralogy of Fallot (TOF) and 8 normal subjects by magnetic resonance imaging in long- and short-axis views. We reconstructed the right ventricles in 3 dimensions using the piecewise smooth subdivision surface method. Shape was analyzed from cross-sectional contours generated by intersecting the right ventricle with 20 planes evenly spaced from apex to tricuspid annulus. Patients with TOF had dilated right ventricles compared with normal (end-diastolic volume index 216 +/- 99 vs 81 +/- 16 ml/m(2), p <0.001) but near-normal function (ejection fraction 40 +/- 9% vs 48 +/- 12%, respectively, p = NS). RV shape in patients with TOF differed from normal subjects in several ways. First, the right ventricle had a larger normalized cross-sectional area in patients with TOF (p <0.01 in apical planes). Second, the cross-sectional shape was rounder in patients with TOF (p <0.05 in apical planes). Also, the interventricular septum underwent relatively less enlargement so that it comprised only 27 +/- 4% of total RV surface area in patients with TOF, compared with 33 +/- 2% in normal subjects (p = 0.0001). In addition, the right ventricle in patients with TOF exhibited bulging basal to the tricuspid valve (4 +/- 4% of total RV length), unlike normals (1 +/- 2%, p <0.001). This basal bulging was amplified by tilting of the tricuspid annulus (29 +/- 11 degrees vs 15 +/- 7 degrees , respectively, p <0.005). In conclusion, the right ventricle remodels in several directions rather than following a shape continuum. Characterization of RV remodeling from 3-dimensional reconstructions provides novel insights.

Evaluation of Midwall Systolic Function in Left Ventricular Hypertrophy: A Comparison of 3-Dimensional Versus 2-Dimensional Echocardiographic Indices

OBJECTIVE

This study investigated the sensitivity of 3-dimensional (3D) midwall ejection fraction (EF) (3DEF(mw)) to the presence of left ventricular (LV) hypertrophy (LVH) in comparison with conventional echocardiographic indices for systolic function.

BACKGROUND

EF and fractional shortening (FS) do not reflect the prognosis of patients with LVH. Midwall mechanics better represent the true function in LVH. However, midwall FS (FS(mw)) interrogates a limited region of LV. We developed a method for determining 3DEF(mw).

METHODS

This study compared 3DEF(mw) with 2-dimensional (endocardial EF [EF(endo)], endocardial FS, FS(mw), and systolic tissue velocity) and 3D (3D EF(endo) and mitral annular motion [MAM]) echocardiographic indices in 28 patients with essential hypertension and LV mass index by M-mode greater than 125 g/m(2) versus 21 healthy individuals.

RESULTS

Systolic function assessed by EF(endo), endocardial FS, 3D EF(endo), and systolic tissue velocity did not differ between the two groups, but MAM (11.6 vs 14.0 mm), FS(mw) (14.7 vs 18.2%), and 3DEF(mw) (36.6 vs 44.1%) were significantly decreased in LVH compared with normal. Only 3 parameters correlated significantly with both the M-mode and 3D measurements of LV mass index: FS(mw) (r = -0.74 [M-mode]; r = -0.48 [3D]), 3DEF(mw) (r = -0.63 [M-mode]; r = -0.68 [3D]), and MAM (r = -0.43 [M-mode]; r = -0.36 [3D]). Midwall indices FS(mw) (F = 40.4) and 3DEF(mw) (F = 26.5) better discriminated LVH and normal groups than MAM or endocardial indices.

CONCLUSIONS

The 3DEF(mw) method discriminates the systolic function of LVH and normal groups, and correlates with the degree of hypertrophy. By avoiding the limitations of FS(mw) or MAM, 3DEF(mw) provides a more comprehensive metric of systolic function in patients with LVH.

Rapid full volume data acquisition by real-time 3-dimensional echocardiography for assessment of left ventricular indexes in children: A validation study compared with magnetic resonance imaging

OBJECTIVE

We sought to assess the feasibility, accuracy, and reproducibility of a rapid full volume acquisition strategy using real-time (RT) 3-dimensional (3D) echocardiography (3DE) for measurement of left ventricular (LV) volumes, mass, stroke volume (SV), and ejection fraction (EF) in children.

METHODS

A total of 19 healthy children (mean 10.6 +/- 2.8 years, 11 male and 9 female) were prospectively enrolled in this study. RT 3DE was performed using an ultrasound system to acquire full volume 3D dataset from the apical window with electrocardiographic triggering in 8 s/dataset. The images were processed offline using software. The LV endocardial and epicardial borders were traced manually to derive LV end-systolic volume, end-diastolic volume, mass, SV, and EF. Magnetic resonance imaging (MRI) studies were performed on a 1.5-T scanner using a breath hold 2-dimensional cine-FIESTA (fast imaging employing steady-state acquisition) sequence.

RESULTS

All RT 3DE and MRI data were acquired successfully for analysis. Measurements of LV end-systolic volume, end-diastolic volume, mass, SV, and EF by RT 3DE correlated well by Pearson regression ( r = 0.86-0.97, P < .001) and agreed well by Bland-Altman analysis with MRI. The interobserver and intraobserver variability of RT 3DE measurements were less than 5%.

CONCLUSIONS

This prospective study demonstrated that RT 3DE measurements of LV end-systolic volume, end-diastolic volume, mass, SV, and EF in children using rapid full volume acquisition strategy are feasible, accurate, and reproducible and are comparable with MRI measurements.

Three-dimensional assessment of two-dimensional technique for evaluation of right ventricular function by tricuspid annulus motion

BACKGROUND

Measurement of tricuspid annulus motion (TAM) is an easy way to estimate right ventricular ejection fraction (RVEF). However the accuracy of two-dimensional (2-D) methods for analyzing the three-dimensional (3-D) structure of the tricuspid annulus has not been evaluated.

OBJECTIVE

This study evaluated the accuracy with which 2-D measurements of TAM reflect RVEF using 3-D reconstructions of the heart at end diastole (ED) and end systole (ES).

METHODS

2-D echocardiographic studies were performed on 12 subjects and used to reconstruct the RV and tricuspid annulus in 3-D at ED and ES. Measurements of TAM from medial and lateral positions on the annulus were selected from the standard echocardiographic apical four-chamber view. The minimum and maximum possible TAM values, RV volumes, and movement of the apex of the heart along the trajectory of TAM were calculated from the 3-D reconstructions.

RESULTS

TAM correlated highly with RVEF (r > or = 0.90). Values found by 2-D and 3-D techniques were not significantly different. Correcting TAM for apex motion did not improve correlation. Summation of medial and lateral TAM data increased correlation values slightly relative to lateral TAM alone. Regional aberrant contractility degraded the predictive value of TAM.

CONCLUSION

Estimation of RVEF from 2-D echo measurement of TAM is accurate, especially when medial and lateral TAM are summed, except in patients with severe apical RV dysfunction.

Three-dimensional visual guidance improves the accuracy of calculating right ventricular volume with two-dimensional echocardiography

Three-dimensional guidance programs have been shown to increase the reproducibility of 2-dimensional (2D) left ventricular volume calculations, but these systems have not been tested in 2D measurements of the right ventricle. Using magnetic fields to identify the probe location, we developed a new 3-dimensional guidance system that displays the line of intersection, the plane of intersection, and the numeric angle of intersection between the current image plane and previously saved scout views. When used by both an experienced and an inexperienced sonographer, this guidance system increases the accuracy of the 2D right ventricular volume measurements using a monoplane pyramidal model. Furthermore, a reconstruction of the right ventricle, with a computed volume similar to the calculated 2D volume, can be displayed quickly by tracing a few anatomic structures on 2D scans.