Scott Settlemier

Characterization of degenerative mitral valve disease using morphologic analysis of real-time three-dimensional echocardiographic images: objective insight into complexity and planning of mitral valve repair.

Background—Presurgical planning of mitral valve (MV) repair in patients with Barlow disease (BD) and fibroelastic deficiency (FED) is challenging because of the inability to assess accurately the complexity of MV prolapse. We hypothesized that the etiology of degenerative MV disease (DMVD) could be objectively and accurately ascertained using parameters of MV geometry obtained by morphological analysis of real-time 3D echocardiographic (RT3DE) images. Methods and Results—Seventy-seven patients underwent transesophageal RT3DE study: 57 patients with DMVD studied intraoperatively (28 BD, 29 FED classified during surgery) and 20 patients with normal MV who were used as control subjects (NL). MVQ software (Philips) was used to measure parameters of annular dimensions and geometry and leaflet surface area, including billowing volume and height. The Student t test and multinomial logistic regression was performed to identify parameters best differentiating DMVD patients from normal as well as FED from BD. Morphological analysis in the DMVD group revealed a progressive increase in multiple parameters from NL to FED to BD, allowing for accurate diagnosis of these entities. The strongest predictors of the presence of DMVD included billowing height and volume. Three-dimensional billowing height with a cutoff value of 1.0 mm differentiated DMVD from NL without overlap, and billowing volume with a cutoff value 1.15 mL differentiated between FED and BD without overlap. Conclusions—Morphological analysis as a form of decision support in assessing MV billowing revealed significant quantifiable differences between NL, FED, and BD patients, allowing accurate classification of the etiology of MV prolapse and determination of the anticipated complexity of repair.Pre-surgical planning of mitral valve (MV) repair in patients with Barlows disease (BD) and fibroelastic deficiency (FED) is challenging due to inability to accurately assess the complexity of MV prolapse. We hypothesized that the etiology of degenerative MV disease (DMVD) could be objectively and accurately determined using morphologic analysis of MV geometry from real-time 3D echocardiographic (RT3DE) images. Seventy-seven patients underwent transesophageal RT3DE study: 57 patients with DMVD studied intra-operatively (28 BD, 29 FED classified during surgery) and 20 patients with normal MV who were used as controls (NL). Parameters of annular dimensions and geometry, and leaflet surface area were measured. Morphologic analysis in the DMVD group revealed a progressive increase in multiple parameters from NL to FED to BD, allowing for accurate diagnosis of these entities. Strongest predictors of the presence of DMVD included billowing height and volume. 3D billowing height with a cutoff value of 1.0 mm differentiated DMVD from NL without overlap, and billowing volume with a cutoff value 1.15 ml differentiated between FED and BD without overlap. Morphologic analysis as a form of decision support of assessing MV billowing revealed significant quantifiable differences between NL, FED and Barlow, allowing accurate classification of the etiology of MV prolapse and determination of the anticipated complexity of repair‥

Characterization of Degenerative Mitral Valve Disease Using Morphologic Analysis of Real-Time 3D Echocardiographic Images: Objective Insight into Complexity and Planning of Mitral Valve Repair

Background—Presurgical planning of mitral valve (MV) repair in patients with Barlow disease (BD) and fibroelastic deficiency (FED) is challenging because of the inability to assess accurately the complexity of MV prolapse. We hypothesized that the etiology of degenerative MV disease (DMVD) could be objectively and accurately ascertained using parameters of MV geometry obtained by morphological analysis of real-time 3D echocardiographic (RT3DE) images. Methods and Results—Seventy-seven patients underwent transesophageal RT3DE study: 57 patients with DMVD studied intraoperatively (28 BD, 29 FED classified during surgery) and 20 patients with normal MV who were used as control subjects (NL). MVQ software (Philips) was used to measure parameters of annular dimensions and geometry and leaflet surface area, including billowing volume and height. The Student t test and multinomial logistic regression was performed to identify parameters best differentiating DMVD patients from normal as well as FED from BD. Morphological analysis in the DMVD group revealed a progressive increase in multiple parameters from NL to FED to BD, allowing for accurate diagnosis of these entities. The strongest predictors of the presence of DMVD included billowing height and volume. Three-dimensional billowing height with a cutoff value of 1.0 mm differentiated DMVD from NL without overlap, and billowing volume with a cutoff value 1.15 mL differentiated between FED and BD without overlap. Conclusions—Morphological analysis as a form of decision support in assessing MV billowing revealed significant quantifiable differences between NL, FED, and BD patients, allowing accurate classification of the etiology of MV prolapse and determination of the anticipated complexity of repair.Pre-surgical planning of mitral valve (MV) repair in patients with Barlows disease (BD) and fibroelastic deficiency (FED) is challenging due to inability to accurately assess the complexity of MV prolapse. We hypothesized that the etiology of degenerative MV disease (DMVD) could be objectively and accurately determined using morphologic analysis of MV geometry from real-time 3D echocardiographic (RT3DE) images. Seventy-seven patients underwent transesophageal RT3DE study: 57 patients with DMVD studied intra-operatively (28 BD, 29 FED classified during surgery) and 20 patients with normal MV who were used as controls (NL). Parameters of annular dimensions and geometry, and leaflet surface area were measured. Morphologic analysis in the DMVD group revealed a progressive increase in multiple parameters from NL to FED to BD, allowing for accurate diagnosis of these entities. Strongest predictors of the presence of DMVD included billowing height and volume. 3D billowing height with a cutoff value of 1.0 mm differentiated DMVD from NL without overlap, and billowing volume with a cutoff value 1.15 ml differentiated between FED and BD without overlap. Morphologic analysis as a form of decision support of assessing MV billowing revealed significant quantifiable differences between NL, FED and Barlow, allowing accurate classification of the etiology of MV prolapse and determination of the anticipated complexity of repair‥

A three-dimensional insight into the complexity of flow convergence in mitral regurgitation: adjunctive benefit of anatomic regurgitant orifice area

Mitral effective regurgitant orifice area (EROA) using the flow convergence (FC) method is used to quantify the severity of mitral regurgitation (MR). However, it is challenging and prone to interobserver variability in complex valvular pathology. We hypothesized that real-time three-dimensional (3D) transesophageal echocardiography (RT3D TEE) derived anatomic regurgitant orifice area (AROA) can be a reasonable adjunct, irrespective of valvular geometry. Our goals were to 1) to determine the regurgitant orifice morphology and distance suitable for FC measurement using 3D computational flow dynamics and finite element analysis (FEA), and (2) to measure AROA from RT3D TEE and compare it with 2D FC derived EROA measurements. We studied 61 patients. EROA was calculated from 2D TEE images using the 2D-FC technique, and AROA was obtained from zoomed RT3DE TEE acquisitions using prototype software. 3D computational fluid dynamics by FEA were applied to 3D TEE images to determine the effects of mitral valve (MV) orifice geometry on FC pattern. 3D FEA analysis revealed that a central regurgitant orifice is suitable for FC measurements at an optimal distance from the orifice but complex MV orifice resulting in eccentric jets yielded nonaxisymmetric isovelocity contours close to the orifice where the assumptions underlying FC are problematic. EROA and AROA measurements correlated well (r = 0.81) with a nonsignificant bias. However, in patients with eccentric MR, the bias was larger than in central MR. Intermeasurement variability was higher for the 2D FC technique than for RT3DE-based measurements. With its superior reproducibility, 3D analysis of the AROA is a useful alternative to quantify MR when 2D FC measurements are challenging.

Quantitative assessment of left ventricular volume and ejection fraction using two-dimensional speckle tracking echocardiography

AIMS Two-dimensional speckle tracking echocardiography (2DSTE) allows measurements of left ventricular (LV) volumes and LV ejection fraction (LVEF) without manual tracings. Our goal was to determine the accuracy of 2DSTE against real-time 3D echocardiography (RT3DE) and against cardiac magnetic resonance (CMR) imaging. METHODS AND RESULTS In Protocol 1, 2DSTE data in the apical four-chamber view (iE33, Philips) and CMR images (Philips 1.5T scanner) were obtained in 20 patients. The 2DSTE data were analysed using custom software, which automatically performed speckle tracking analysis throughout the cardiac cycle. LV volume curves were generated using the single-plane Simpsons formula, from which end-diastolic volume (LVEDV), end-systolic volume (LVESV), and LVEF were calculated. In Protocol 2, the 2DSTE and RT3DE data were acquired in 181 subjects. RT3DE data sets were acquired, and LV volumes and LVEF were measured using QLab software (Philips). In Protocol 1, excellent correlations were noted between the methods for LVEDV (r=0.95), ESV (r=0.95), and LVEF (r=0.88). In Protocol 2, LV volume waveforms suitable for analysis were obtained from 2DSTE images in all subjects. The time required for analysis was <2 min per patient. Excellent correlations were noted between the methods for LVEDV (r=0.95), ESV (r=0.97), and LVEF (r=0.92). However, 2DSTE significantly underestimated LVEDV, resulting in a mean of 8% underestimation in LVEF. Intra- and inter-observer variabilities of 2DSTE were 7 and 9% in LV volume and 6 and 8% in LVEF, respectively. CONCLUSIONS Two-dimensional speckle tracking echocardiography measurements resulted in a small but significant underestimation of LVEDV and EF compared with RT3DE. However, the accuracy, low intra- and inter-observer variabilities and speed of analysis make 2DSTE a potentially useful modality for LV functional assessment in the routine clinical setting.

Estimation of Radial Strain and Rotation Using a New Algorithm Based on Speckle Tracking

BACKGROUND The aim of this study was to test the ability of a new algorithm to accurately measure point-to-point Lagrangian strain (LS) and local rotation (ROT). Change in distance between 2 separate regions of interest (ROIs) can theoretically be computed with speckle tracking (SpT) and used to calculate LS in any tissue location with angle independence and high spatial resolution. Similarly, tracking an ROI relative to a fixed point should provide an estimate of ROT. METHODS Two dynamic phantoms (60 beats/min) were scanned in short axis at frame rates of 30, 60, and 90 Hz. To estimate LS, 2 ROIs were positioned immediately beneath the inner and outer borders of the superior wall of the first phantom and tracked using SpT. LS derived from SpT (SpT-LS) was compared with LS measured by sonomicrometers placed on the inner and outer walls of the phantom (SN-LS). To estimate ROT, the rotational vectors around the centroid of a second phantom were calculated for 3 epicardial bead targets imaged with gated computed tomography (CT) and compared with measurements derived from SpT. RESULTS There was a significant correlation between SpT-LS and SN-LS at 30 Hz (R(2) = 0.99; P < .0001), 60 Hz (R(2) = 0.98; P < .0001), and 90 Hz (R(2) = 0.99; P < .0001). There was also a significant correlation between ROT derived from SpT and ROT derived from CT: R(2) = 0.97 (P < .0001) at 30 Hz, R(2) = 0.95 (P < .0001) at 60 Hz, and R(2) = 0.98 (P < .0001) at 90 Hz. CONCLUSIONS Point-to-point SpT permits the determination of LS between 2 distinct tissue regions as well as ROT measurement of specific tissue regions without the need for border detection.

FULLY AUTOMATED QUANTIFICATION OF LEFT VENTRICULAR AND LEFT ATRIAL VOLUMES FROM TRANSTHORACIC 3D ECHOCARDIOGRAPHY: A VALIDATION STUDY

Cardiac chamber quantification from 3D transthoracic echocardiography (3D TTE) has been shown to be superior to measurements obtained from 2D studies. However, integration of 3D TTE into routine clinical practice has been limited by the time-consuming workflow and need for 3D expertise. We assessed

Real-time motion tracking using 3D ultrasound

Three-dimensional (3D) ultrasound is ideally suited to monitor internal organ motion since it offers real-time volumetric imaging without exposing the patient to radiation. We extend a two dimensional (2D) region-tracking algorithm, which was originally used in computer vision, to monitor internal organ motion in 3D. A volume of interest is first selected in an ultrasound volume as a reference. The sum of squared differences is used as the similarity measure to register the reference to each successive volume frame. A transformation model is used to describe the motion and geometric deformation of the reference. The Gauss-Newton method is used to solve the optimization problem. In order to improve the algorithms efficiency, the Jacobian matrix is decomposed as a product of a time-varying matrix and a constant matrix. The constant matrix is pre-computed to reduce the load of online computation. The algorithm was tested on targets under respiratory motion and cardiac motion. The experimental results show that the transformation model of the algorithm can approximate the geometric distortion of the reference template. With a properly selected reference with rich texture information, the algorithm is sufficiently accurate and robust to follow target motion, and fast enough to be used in real time.

Temporal enhancement of two-dimensional color doppler echocardiography

Two-dimensional color Doppler echocardiography is widely used for assessing blood flow inside the heart and blood vessels. Currently, frame acquisition time for this method varies from tens to hundreds of milliseconds, depending on Doppler sector parameters. This leads to low frame rates of resulting video sequences equal to tens of Hz, which is insufficient for some diagnostic purposes, especially in pediatrics. In this paper, we present a new approach for reconstruction of 2D color Doppler cardiac images, which results in the frame rate being increased to hundreds of Hz. This approach relies on a modified method of frame reordering originally applied to real-time 3D echocardiography. There are no previous publications describing application of this method to 2D Color Doppler data. The approach has been tested on several in-vivo cardiac 2D color Doppler datasets with approximate duration of 30 sec and native frame rate of 15 Hz. The resulting image sequences had equivalent frame rates to 500Hz.

Image-based speckle tracking for tissue motion characterization in a deformable cardiovascular phantom

We present and validate image-based speckle-tracking calipers for quantification of tissue deformation and rotation in dynamic cardiovascular phantom models. Lagrangian strain was computed from the change in distance between caliper regions-of-interest (ROIs) positioned within the wall of a pulsatile phantom and compared with reference measurements derived from cardiac CT imaging. In a torsion phantom, rotational tissue excursion in a 2D plane was estimated and compared with reference values from CT-scan data. Tissue deformation and rotation measurements correlated well with their respective reference measurements. Our algorithm is capable of estimating strain and rotation from distinct tissue regions without requiring explicit cardiac border detection, a step which can be especially challenging in patients with poor acoustic windows.

3D ultrasound guidance system for needle placement procedures

This paper presents an ultrasound guidance system for needle placement procedures. The system integrates a real-time 3D ultrasound transducer with a 3D localizer and a tracked needle to enable real-time visualization of the needle in ultrasound. The system uses data streaming to transfer real-time ultrasound volumetric images to a separate workstation for visualization. Multi-planar reconstructions of the ultrasound volume are computed at the workstation using the tracking information, allowing for real-time visualization of the needle in ultrasound without aligning the needle with the transducer. The system may simplify the needle placement procedure and potentially reduce the levels of skill and training needed to perform accurate needle placements. The physician can therefore focus on the needle placement procedure without paying extra attention to perfect mid-plane alignment of the needle with the ultrasound image plane. In addition, the physician has real-time visual feedback of the needle and the target, even before the needle enters the patients skin, allowing the procedure to be easily, safely and accurately planned. The superimposed needle can also greatly improve the sometimes poor visualization of the needle in an ultrasound image (e.g. in between ribs). Since the free-hand needle is not inserted through any fixed needle channel, the physician can enjoy full freedom to select the needles orientation or position. No cumbersome accessories are attached to the ultrasound transducer, allowing the physician to use his or her previous experience with regular ultrasound transducers. 3D Display of the target in relation to the treatment volume can help verify adequacy of tumor ablation as well.