Clinical Investigation
3D Echocardiography: Value-Added Applications
Three-Dimensional Modeling of the Right Ventricle from Two-Dimensional Transthoracic Echocardiographic Images: Utility of Knowledge-Based Reconstruction in Pulmonary Arterial Hypertension

https://doi.org/10.1016/j.echo.2013.05.007Get rights and content

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.

Section snippets

Study Design and Population

Patients with World Health Organization group I PAH were recruited prospectively from the pulmonary hypertension clinic at the University of Chicago for same-day TTE and CMR, the latter of which was used as a reference standard. Recruitment specifically focused on patients who had expressed interest in ongoing research or had participated in prior clinical trials. Patients with contraindications to noncontrast CMR, such as inability to comply with breath-hold instructions, severe

Results

From November 2011 to October 2012, 29 patients were recruited and agreed to participate in the study. Two patients were excluded: one because of changes in position during TTE that resulted in severe image misalignment and one because of refusal to undergo CMR. Approximately 10 additional patients were approached but declined to participate. Twenty-seven patients (96% women) were included in the final analysis. Patient characteristics are displayed in Table 2. The mean number of acquisitions

Discussion

To our knowledge, this is the first study to demonstrate that the assessment of RV volumes and systolic function by KBR is feasible, accurate, and reproducible in patients with PAH. Moreover, KBR-derived volumes and EF show modest correlations with widely used clinical markers. We anticipate that KBR could fill an important gap in the care of patients with PAH, because echocardiographic assessment of the right ventricle is a notoriously difficult endeavor. The complex geometry of the right

Conclusions

Three-dimensional reconstruction of the RV endocardium from 2D transthoracic echocardiographic images obtained in patients with PAH, as accomplished by KBR, is feasible, accurate, and reproducible, as demonstrated in a small cohort. Larger studies are needed to confirm these results and to determine the practicality of this approach in daily patient care and as an end point in clinical trials.

Acknowledgments

Sam Alkek of VentriPoint Diagnostics Ltd. performed the CMR tracings for this project. We would also like to thank the University of Chicago Pulmonary Hypertension Research Team, including Lira Palen, MS, RN, Cherylanne Glassner, BS, RN, Sandra Coslet, RN, and Donneea Edwards-Moore, RN, for their assistance with this project.

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Cited by (32)

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    Three-dimensional imaging is a promising approach to overcome this limitation. There are two distinct approaches to 3-dimensional imaging of the RV: use of a special matrix-array transducer to fully cover the entire RV and knowledge-based reconstruction of the RV based on 2-dimensional images with spatial position and orientation of the probe defined by a magnetic field tracking system [44,45]. Three-dimensional echo RV measurements are reproducible [46], and both approaches agree reasonably well with cardiac magnetic resonance volumes [44].

  • Three-dimensional Echocardiography in Congenital Heart Disease: An Expert Consensus Document from the European Association of Cardiovascular Imaging and the American Society of Echocardiography

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    Bias, intra- and inter-observer reliability were good, and knowledge-based 3D reconstruction was slightly better than semi-automated border detection method in this regard. In adults with a systemic RV111,119 and pulmonary arterial hypertension, values have shown good agreement with MRI.120,121 Limitations of the knowledge-based technique include the necessity for a tracked ultrasound transducer and for the patient to remain still throughout the study.

  • Echocardiographic Applications in the Diagnosis and Management of Patients with ARVC

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

    2015, Journal of the American Society of Echocardiography
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    The piecewise smooth subdivision surface technique itself also has greater accuracy over the conventional Beutel method for RV volume reconstruction in vivo by 3DE.22 Our limits of agreement are clinically acceptable compared with the gold standard of CMRI, slightly more favorable than those obtained previously in idiopathic PH,10 and similar to previous work in children following surgical repair of tetralogy of Fallot.22 A potential explanation for these differences might be our quantification of RV volumes by CMRI using a transaxial stack of RV slices rather than the short-axis stack approach.

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    In a larger group of patients, we also demonstrated the unique and diverse nature of RV shapes that occur in the adult CHD population with previous conduit surgery. The use of TTE-3DKBR for RV volume and function assessment has been validated in TOF, transposition of the great arteries, and pulmonary arterial hypertension.6,11-15 The absence of a true RVOT with lack of movement or change in shape from diastole to systole separates the RV-PA conduit shapes from other diagnoses.

  • Multimodality imaging in pulmonary hypertension

    2015, Canadian Journal of Cardiology
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    RT3DE has demonstrated superiority over other conventional TDE methods in the assessment of RV volume and function (RT3DE-derived RV ejection fraction).31,32 Additionally, it can be useful to better characterize RV morphofunctional adaptations to specific causes of PH, such as complex congenital heart disease and left-sided valvular or ventricular diseases.33 In this regard, Grapsa et al.,34 using RT3DE to assess RV volumes and tricuspid valve mobility, demonstrated that RV remodelling differs with the various causes of PH, with the most adverse remodelling being in patients with PAH.

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This project was supported by a grant from VentriPoint Diagnostics Ltd. (Seattle, WA).

The guest editor for this report was Thomas Ryan, MD, FASE.

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