Automated Border Detection Research Articles

Invasive Haemodynamic Monitoring: Concepts and Practical Approaches

The goal of haemodynamic care is to ensure adequate organ blood flow and oxygen supply. Clinical signs of organ perfusion have limited value in estimation of tissue perfusion, but invasive haemodynamic monitoring is needed to gain information of the underlying pathological condition and to guide oxygen delivery and haemodynamic therapy. Many of the available haemodynamic measurements involve pulmonary artery (PA) catheterization. Pressure measurements from PA catheters require meticulous attention to the dynamic properties of the transducer-pressure line system and appreciation of pressure variation owing to respiration. New techniques of continuous measurement of mixed venous oxygen saturation and cardiac output provide valuable trend data, allowing immediate diagnosis and treatment of pathological changes. Fast-response thermistor PA catheters are useful tools for estimating right ventricular function. Although clinicians generally regard PA-catheter data as a valuable therapy guide, few studies showing the beneficial influence on overall outcome have been carried out, and some studies have reported suboptimal understanding and utilization of these data. Transoesophageal echocardiography (TEE) is also a valuable monitor of left ventricular systolic and diastolic function and myocardial ischaemia in anaesthetized patients and in intensive care settings, but it requires a trained operator and is time-consuming. Continuously displayed TEE data, obtainable with automatic border detection, will make TEE even more useful in the near future. More effective monitors of perfusion and oxygenation of individual organs are needed. Less invasive techniques are also constantly sought. Combining data from several noninvasive monitors, including measurements of pulse oximetric 02 saturation, transthoracic impedance cardiac output and transcutaneous oxygen tension, has been reported to reflect closely changes obtained with more invasive monitoring.

Left ventricular performance assessed by echocardiographic automated border detection and arterial pressure.

Automated echocardiographic measures of left ventricular (LV) cavity area are closely correlated with changes in volume and can be coupled with LV pressure (PLV) to construct pressure-area loops in real time. The objective was to rapidly estimate LV contractility from end-systolic relationships of cavity area (as a surrogate for LV volume) and central arterial pressure (Pa) (as a surrogate for PLV) in a canine model using automated algorithms. In eight anesthetized mongrel dogs, we simultaneously measured PLV, LV area, and Pa (fluid-filled catheter). End-systolic pressure-area relationships in terms of pressure-area elastance (E'es)] from pressure-area loops during inferior vena caval occlusions were determined during basal conditions (control), dobutamine infusion (5-10 micrograms.mg-1.min-1), and after bolus propranolol (2 mg/kg) with both PLV and Pa by semiautomated and automated iterative regression methods. E'es increased during dobutamine infusion and decreased after propranolol infusion in all animals and with all iterative methods. Estimates of Ees from Pa were closely correlated with E'es from PLV by both the semiautomated and automated methods (r = 0.93; P < 0.01). The relationship between E'es obtained from Pn for the two methods was also closely correlated. Although the automated methods displayed larger differences from the semiautomated iterative technique by Bland-Altman analysis, the change in E'es with all techniques during dobutamine infusion and after propranolol infusion was of similar magnitude and direction among the three techniques. Greater variability with the dobutamine runs was partially due to abnormally conducted ventricular beats that minimized the number of consecutive beats that could be used for these analyses. We conclude that on-line Pa recordings from fluid-filled catheters can be used with echocardiographic automated border detection to rapidly calculate E'es as a means to estimate LV contractility.

An algorithm for real-time, continuous evaluation of left ventricular mechanics by single-beat estimation of arterial and ventricular elastance.

We describe a computer algorithm that allows continuous, real-time evaluation of ventricular elastance (Ees), arterial elastance (Ea), and their coupling ratio in a clinical setting. In the conventional pressure-volume analysis of left ventricular (LV) contractility, invasive methods of volume determination and a significant, rapid preload reduction are required to generate Ees. With the help of automated border detection by transesophageal echocardiography, and a technique of estimating peak LV isovolumic pressure, Ea and Ees were determined from a single cardiac beat without the need for preload reduction. A comparison of results obtained by a conventional approach and the new algorithm technique, showed good correlation for Ea (r = 0.86, p < 0.001) and Ees (r = 0.74, p = 0.001). Bias analysis showed a bias (d) of 1.47 mmHg/cm2 for Ea with a standard deviation (SD) of 7.03 mmHg/cm2, and upper (d+2SD) and lower(d-2SD) limits of agreement of 15.24 mmHg/cm2 and -12.31 mmHg/cm2, respectively. Bias analysis showed a bias of -1.42 mmHg/cm2 for Ees with a SD of 4.88 mmHg/cm2, and limits of agreement of 8.15 mmHg/cm2 and -10.98 mmHg/cm2. The algorithm's stability to artifacts was also analyzed by comparing magnitudes of residuals of Ea and Ees from source signals with and without noise. With Ea differing by an average of 1.036 mmHg/cm2 and Ees differing by an average of 0.836 mmHg/cm2, the algorithm was found to be stable to artifacts in the source signals.

Validation of Automated Border Detection in Intravascular Ultrasound Images.

Intravascular ultrasound (IVUS) imaging provides cross-sectional views of the vessel lumen; however, lumen measurements still rely on operator-dependent border delineation and time-consuming lumen tracings. We tested a new system for automated lumen border detection in IVUS images based on acoustic quantification of blood and vessel wall. In 10 rabbits, 29 segments of the aorta were imaged in vivo using a 2.9-Fr IVUS catheter. IVUS images were obtained during motorized pullbacks of aortic segments of 18 mm length. Automated measurements of lumen dimensions were compared to automated measurements of a second pullback through the same segment, lumen measurements derived from visual border tracings in IVUS images, and to quantitative angiography. The automated system showed good reproducibility: Correlations for repeated measurements of lumen area, maximal and minimal lumen diameters were r = 0.97, r = 0.91, and r = 0.93, respectively. Automated measurements also correlated well to visual image analysis (lumen area, r = 0.97; maximal lumen diameter, r = 0.89; minimal lumen diameter, r = 0.89) and to angiographic measurements (lumen area, r = 0.93; lumen diameter, r = 0.95). In 12% of the images, the automated system overestimated lumen dimensions because of weak wall signals in the presence of echolucent structures next to the wall. Signal artifacts from the IVUS catheter itself or strong blood backscatter resulted in lumen underestimation in 6% of the images. Over- and underestimation of lumen by the border detection system were often associated with eccentric catheter position. Thus, lumen measurements in vivo IVUS images can be performed using an automated border detection system based on acoustic quantification of blood and vessel wall. The system allows reproducible and accurate measurements of lumen area and diameters. (ECHOCARDIOGRAPHY, Volume 13, November 1996)

Automated echocardiographic analysis of systemic ventricular performance in hypoplastic left heart syndrome

In patients with hypoplastic left heart syndrome, the right ventricle is positioned as the systemic ventricle. Monitoring its function is important but difficult because of its unusual position and geometry. The purposes of this study were to determine the feasibility of applying automatic echocardiographic measurements to the evaluation of right ventricular function in patients with hypoplastic left heart syndrome and to compare their function with that of normal subjects. Eleven patients with hypoplastic left heart syndrome (mean age 1.6 years) were evaluated with automatic border detection. Images were adequate if greater than 85% of the endocardium was being tracked. Systolic indexes were fractional area change and peak emptying rate; diastolic indexes were peak filling rate and the proportion of filling that occurred during rapid filling, diastasis, and atrial contraction. These data were compared with those in 18 normal control subjects. Three patients had completed stage 1 (aortic reconstruction, surgical shunt, and atrial septectomy), three patients had completed stage 2 (hemi-Fontan), and five patients had completed stage 3 (Fontan). Images were adequate in all cases. Fractional area change and peak emptying rate were significantly lower in the patients with hypoplastic left heart syndrome compared with control subjects (38% ± 6% versus 61% ± 10% and 3.5 ± 0.9 versus 5.3 ± 1.3 sec −1, respectively). Peak filling rate was significantly lower (4.1 ± 1.3 versus 6.6 ± 2.3 sec −1) and atrial contribution was significantly higher (18% ± 7% versus 12% ± 4%) in the patients. Automated echocardiographic analysis is feasible in assessing systemic ventricular function in children with hypoplastic left heart syndrome. These patients have abnormal systolic and diastolic function. Automatic border detection may be useful in detecting and monitoring systemic ventricular dysfunction as these patients progress through the surgical stages of repair.

Echocardiographic assessment of diastolic function

Echocardiographic assessment of diastolic function

Aortic elastic properties with transesophageal echocardiography with automated border detection: Validation according to regional differences between proximal and distal descending thoracic aorta

We have previously described the use of transesophageal echocardiography with automated border detection to quantify regional aortic elastic properties. The purpose of this study was to validate this technique further by measuring regional variations of aortic elastic properties and comparing them with previously published data acquired by invasive methods. In nine anesthetized, closed-chest dogs, aortic pressure and lumenal area (transesophageal echocardiography with automated border detection) signals were recorded simultaneously at two aortic sites: just distal to the branching site of the left subclavian artery (proximal) and at the level of the diaphragm (distal). Instantaneous wall thickness was estimated by combining M-mode measurement of aortic end-diastolic thickness with instantaneous lumenal area. Data were acquired over a wide range of loading conditions, generated by inferior vena caval balloon occlusion. Aortic compliance per unit length, midwall radius, midwall stress, and incremental elastic modulus were computed. Aortic midwall radius and incremental elastic modulus values for proximal and distal aortic sites were compared at a common level of midwall stress. Compliance per unit length was higher in the proximal compared with the distal descending thoracic aorta (0.013 ± 0.003 versus 0.008 ± 0.003 cm 2/mm Hg; mean ± SD; p = 0.0011). Midwall radius was larger at the proximal location (0.76 ± 0.07 cm versus 0.64 ± 0.07 cm; p = 0.0001), whereas incremental elastic modulus was greater distally (0.799 ± 0.052 dynes × 10 6/cm 2 versus 0.912 ± 0.130 dynes × 10 6/cm 2; p = 0.02). Lower compliance values at the distal site of the descending thoracic aorta resulted from greater wall stiffness and a smaller radius. Transesophageal echocardiography with automated border detection provides reliable measurements of instantaneous aortic areas necessary for quantifying regional elastic properties.

Echocardiographic automatic myocardial border detection: A novel technique applicable for normal and abnormal ventricles: Farooq A. Chandhry, Rajesh Sehgal, Edwin L. Dove, Reena Sinha, Michael J. Vonesh, Bonnie J. Kane, Rodney Greene, Krishnan B. Chandran, David D. McPherson. Northwestern University, Chicago, Illinois; University of Iowa, Iowa City, Iowa

Echocardiographic automatic myocardial border detection: A novel technique applicable for normal and abnormal ventricles: Farooq A. Chandhry, Rajesh Sehgal, Edwin L. Dove, Reena Sinha, Michael J. Vonesh, Bonnie J. Kane, Rodney Greene, Krishnan B. Chandran, David D. McPherson. Northwestern University, Chicago, Illinois; University of Iowa, Iowa City, Iowa

Comparison of observer drawn borders to those of an automated border detection algorithm for epicardium and endocardium: Edward A. Geiser MD, David C. Wilson PhD, Dongxing Wang MS, Donald A. Conetta MD, James D. Murphy MD. University of Florida, Gainesville, FL

Comparison of observer drawn borders to those of an automated border detection algorithm for epicardium and endocardium: Edward A. Geiser MD, David C. Wilson PhD, Dongxing Wang MS, Donald A. Conetta MD, James D. Murphy MD. University of Florida, Gainesville, FL

Assessment of preload-adjusted maximal power using echocardiographic automated border detection to assess alterations in left ventricular contractility: William A. Mandarino MS, Christine M. Mahler MS, Michael R. Pinsky MD, John Gorcsan III MD. University of Pittsburgh, Pittsburgh, PA

Assessment of preload-adjusted maximal power using echocardiographic automated border detection to assess alterations in left ventricular contractility: William A. Mandarino MS, Christine M. Mahler MS, Michael R. Pinsky MD, John Gorcsan III MD. University of Pittsburgh, Pittsburgh, PA

AUTOMATIC BORDER DETECTION AND THREE-DIMENSIONAL RECONSTRUCTION WITH ECHOCARDIOGRAPHY

This article reviews two important innovations in echocardiography resulting from the recent advances in the capabilities of microprocessors. The first, automatic endocardial border detection, has been implemented on computers contained entirely within echocardiograph machines and is gaining wide clinical use. The second, three-dimensional imaging, is currently under intense investigation and shows great promise for clinical application. It requires, however, further development of the specialized transducer apparatus necessary for image acquisition and the sophisticated computer-processing capability necessary for image reconstruction and display.

Assessment of diastolic left ventricular filling by echocardiographic automated border detection and comparison with radionuclide ventriculography

To determine whether indexes obtained from a newly developed echocardiographic automated border detection (ABD) technology provide a reliable estimate of left ventricular (LV) diastolic filling, ABD variables of LV filling were compared with volumetric measurements determined by radionuclide angiography. Forty-two patients with a variety of heart diseases (age range, 11 to 76 years) underwent ABD echocardiographic studies on the same day as the radionuclide examination. Technically adequate ABD data could be obtained in 31 patients (74%). Nineteen healthy subjects served as normal controls. Area-time and volume-time waveforms for echocardiographic measurements were obtained from LV short-axis views at the level of the papillary muscles and four-chamber apical views. Both the diastolic indexes derived from the waveform of area change (short-axis view) and volume change (four-chamber apical view) correlated with radionuclide variables. Values measured from the ABD area-time waveform showed the following correlations: peak filling rate ( r = 0.86; standard error of the estimate [SEE] = 0.62), time to peak filling rate ( r = 0.85; SEE = 23.11), rapid filling phase fractional change ( r = 0.79; SEE = 5.51), and atrial filling phase fractional change ( r = 0.71; SEE = 5.82). Correlations of indexes derived from the ABD volume-time waveform were as follows: peak filling rate ( r = 0.87; SEE = 0.50), time to peak filling rate ( r = 0.90; SEE = 22.03), rapid filling fractional change ( r = 0.83; SEE = 5.33), and atrial filling fractional change ( r = 0.77; SEE = 4.68). ABD LV filling parameters in patients with heart disease and normal control subjects were significantly different. Thus ABD data from short-axis and apical views have a strong linear relation with radionuclide ventriculographic measurements and may be used as a method to assess LV diastolic filling.

Automatic Border Detection to Assess Right Ventricular Function Following Surgical Treatment of Thromboembolic Pulmonary Hypertension.

Automatic border detection (ABD) has been developed as a potentially useful means for evaluating ventricular function on line in an automatic fashion. Its success with tracking left ventricular function is established, but little is known about its ability to assess right ventricular (RV) function. Accordingly, 20 patients with severe pulmonary hypertension due to chronic thromboembolic disease underwent standard two-dimensional echocardiography and imaging with ABD before and after pulmonary thromboendarterectomy to correct pulmonary hypertension. ABD-derived results were compared to manually planimetered RV areas calculated from the apical four-chamber view. Doppler tricuspid regurgitant velocity fell significantly with surgery from 4.4 +/- 0.6 to 2.9 +/- 0.7 m/sec (P < 0.001). The mean values for RV areas derived by manual planimetry and ABD were similar, as was fractional area shortening, which improved significantly with surgery (manual 0.24 +/- 0.01 preoperative vs 0.31 +/- 0.11 postoperative, P < 0.05; and ABD 0.19 +/- 0.05 preoperative vs 0.32 +/- 0.15 postoperative, P < 0.001). There was, however, very little correlation between the individual values for ABD versus manually derived RV areas and fractional area shortening, with the best correlation being the RV end-diastolic areas after surgery (y = 0.684x + 7.9, r = 0.564, P = 0.01). These results demonstrate that both manually planimetered RV areas and those determined by ABD can adequately follow changes in ventricular function over time. However, variability within each technique may prevent direct comparison of the absolute values of the two techniques. (ECHOCARDIOGRAPHY, Volume 13, March 1996)

Left ventricular pressure-volume relations with transesophageal echocardiographic automated border detection: Comparison with conductance-catheter technique

Pressure-volume relations are important means used to assess left ventricular (LV) contractility; however, on-line volume acquisition has been limited to the invasive conductance catheter. The objective was to compare simultaneous measures of LV volume by transesophageal echocardiographic automated border detection (ABD) and conductance catheter and their respective pressure-volume relations during steady state and alterations in preload and contractility. Seven dogs had placement of high-fidelity pressure and conductance catheters, a vena caval balloon occluder, and a transesophageal probe. An automated Simpson's rule volume algorithm was used from the transverse four-chamber view. Inotropic modulation was induced with dobutamine in four dogs and propranolol in three. Relative changes in ABD volume were linearly related to conductance volume at steady state with group mean r = 0.93 ± 0.03, standard error of estimate (SEE) = 10 ± 2%. Changes in end-diastolic volume, end-systolic volume, and stroke work with caval occlusion were also significantly correlated: r = 0.93 ± 0.04, SEE = 3.6 ml; r = 0.89 ± 0.04, SEE = 3.8 ± 1.9 ml; and r = 0.86 ± 0.05, SEE = 40 ± 21 mJ, respectively. The overall bias was for absolute ABD volume to be less. Endsystolic and maximal elastance values by ABD were significantly higher than by the conductance method; baseline group average 4.97 ± 0.92 mm Hg/ml versus 2.70 ± 1.15 mm Hg/ml and 6.63 ± 1.66 mm Hg/ml versus 3.20 ± 1.37 mm Hg/ml (p < 0.05), respectively. However, the direction and relative magnitude of changes in elastance with inotropic modulation were similar.

RIGHT VENTRICULAR PERFORMANCE AND LEFT VENTRICULAR ASSIST DEVICE FILLING

Mandarino, W A; Winowich, S; Gorcsan, J III; Gasior, T A; Pham, S; Griffith, B P; Kormos, R L Author Information

Quantitative three-dimensional reconstruction of left ventricular volume with complete borders detected by acoustic quantification underestimates volume

Recently a new acoustic-quantification (AQ) technique has been developed to provide on-line automated border detection with an integrated backscatter analysis. Prior studies have largely correlated AQ areas with volumes without direct comparison of volumes for agreement. By using complete AQ-detected borders as the input to a validated method for three-dimensional echocardiographic (3DE) reconstruction, we can compare an entire cavity volume measured with the aid of AQ against a directly measured volume. This would also explore the possibility of applying AQ to 3DE reconstruction to reduce tracing time and enhance routine applicability. To compare reconstructed volumes with actual values in a stable standard allowing direct volume measurement, the left ventricles of 13 excised animal hearts were studied with a 3DE system that automatically combines two-dimensional (2D) images and their locations. Intersecting 2D views were obtained with conventional scanning and AQ imaging, with gains optimized to permit 3D reconstruction by detecting the most continuous AQ borders for each view, with maximal cavity size. Reconstruction was performed with manually traced central endocardial reflections and AQ-detected borders. 3DE reconstructions of both manually and AQ-detected borders visually reproduced the left ventricular shapes; the AQ reconstructions, however, were consistently smaller. The reconstructed left ventricular (LV) volumes correlated well with actual values by both manual and AQ techniques ( r = 0.93 and 0.88, with standard errors of 2.3 cc and 2.0 cc, p = not significant [NS]). Agreement with actual values was relatively close for the manually traced borders (y = 0.93x + 0.68, mean difference = −0.8 ± 2.2 cc). AQ-derived reconstructions consistently underestimated LV volume by 39 ± 10% (y = 0.62x − 0.09, mean difference = −7.8 ± 3.0 cc, different from manually traced and actual volumes by analysis of variance [ANOVA], F = 69, p < 0.00001). The AQ-detected threshold signal was displaced into the cavity, and volume between walls and false tendons was excluded, leading to underestimation, which increased with increasing cavity volume ( r = 0.76). The AQ technique can therefore be applied to 3DE reconstruction, providing volumes that correlate well with directly measured values in a stable in vitro standard, minimizing observer decisions regarding manual border placement after image acquisition. However, when the complete borders needed for 3D reconstruction are used, absolute volumes are underestimated with current algorithms that integrate backscatter and displace the detected threshold into the ventricular cavity.

The role of automatic endocardial edge detection in the evaluation of left ventricular diastolic function in children

Forty-nine normal children underwent echocardiography to study the role of automatic border detection (ABD) in diastolic evaluation by (1) determining the relationship of diastolic ABD indexes to heart rate and traditional diastolic indexes and (2) establishing inter-observer variability. ABD diastolic indexes were less associated with heart rate than were M-mode and Doppler diastolic indexes. ABD left ventricular peak filling rate correlated with Doppler mitral E wave peak velocity. Interobserver variability for ABD indexes ranged from 4% to 24%. We then compared the ability of ABD left ventricular filling rate to M-mode and Doppler indexes to detect diastolic dysfunction in a test group of 20 children with diastolic disease. ABD left ventricular peak filling rate had the highest sensitivity of all indexes (90%). Thus ABD left ventricular peak filling rate is an accurate index of diastolic function that is readily usable by almost all clinical laboratories.

Evaluation of Left Ventricular Systolic Function by-M-Mode Echo/Phonocardiography and Automated Border Detection(ABD) Echocardiography

Evaluation of Left Ventricular Systolic Function by-M-Mode Echo/Phonocardiography and Automated Border Detection(ABD) Echocardiography

On-Line Assessment of Left Ventricular Function by Automated Border Detection Echocardiography : Comparison with Gated Cardiac Blood Pool Scintigraphy

On-Line Assessment of Left Ventricular Function by Automated Border Detection Echocardiography : Comparison with Gated Cardiac Blood Pool Scintigraphy

P-303 - Assessment of changes in left ventricular function induced by dobutamine and propranolol using echocardiographic automatic border detection in dogs.

P-303 - Assessment of changes in left ventricular function induced by dobutamine and propranolol using echocardiographic automatic border detection in dogs.