Quantification Of Stroke Volume Research Articles

Evaluation of the image quality and validity of handheld echocardiography for stroke volume and left ventricular ejection fraction quantification: a method comparison study.

Bedside quantification of stroke volume (SV) and left ventricular ejection fraction (LVEF) is valuable in hemodynamically compromised patients. Miniaturized handheld ultrasound (HAND) devices are now available for clinical use. However, the performance level of HAND devices for quantified cardiac assessment is yet unknown. The aim of this study was to compare the validity of HAND measurements with standard echocardiography (SE) and three-dimensional echocardiography (3DE). Thirty-six patients were scanned with HAND, SE and 3DE. LVEF and SV quantification was done with automated software for the HAND, SE and 3DE dataset. The image quality of HAND and SE was evaluated by scoring segmental endocardial border delineation (2 = good, 1 = poor, 0 = invisible). LVEF and SV of HAND was evaluated against SE and 3DE using correlation and Bland-Altman analysis. The correlation, bias, and limits of agreement (LOA) between HAND and SE were 0.68 [0.46:0.83], 1.60% [-2.18:5.38], and 8.84% [-9.79:12.99] for LVEF, and 0.91 [0.84:0.96], 1.32ml [-0.36:4.01], 15.54ml [-18.70:21.35] for SV, respectively. Correlation, bias, and LOA between HAND and 3DE were 0.55 [0.6:0.74], -0.56% [-2.27:1.1], and 9.88% [-13.29:12.17] for LVEF, and 0.79 [0.62:0.89], 6.78ml [2.34:11.21], 12.14ml [-26.32:39.87] for SV, respectively. The image quality scores were 9.42 ± 2.0 for the apical four chamber views of the HAND dataset and 10.49 ± 1.7 for the SE dataset and (P < 0.001). Clinically acceptable accuracy, precision, and image quality was demonstrated for HAND measurements compared to SE. In comparison to 3DE, HAND showed a clinically acceptable accuracy and precision for LVEF quantification.

Influence of the area of the aqueduct and region of interest on quantification of stroke volume in healthy volunteers using phase-contrast cine magnetic resonance imaging.

Phase-contrast cine magnetic resonance imaging (PC-MRI) has been used to measure cerebrospinal fluid (CSF) flow dynamics, but the influence of the area of the aqueduct and region of interest (ROI) on quantification of stroke volume (SV) has not been assessed. To assess the influence of the area of the ROI in quantifying the aqueductal SV measured with PC-MRI within the cerebral aqueduct. Nine healthy volunteers (mean age = 29.6 years) were enrolled in the study, and brain MRI examinations were performed on a 3.0-T system. Quantitative analysis of the aqueductal CSF flow was performed using manual ROI placement. ROIs were separately drawn for each of the 12 phases of the cardiac cycle, and changes in aqueduct size during the cardiac cycle were determined. The SV was calculated using 12 different aqueductal ROIs and compared with the SV calculated using a fixed ROI size. There was variation in the size of the aqueduct during the cardiac cycle. In addition, the measured SV increased with a greater area of the ROI. A significant difference in the calculated SVs with the 12 variable ROIs was observed compared with that using a fixed ROI throughout the cardiac cycle. To establish reliable reference values for the SV in future studies, a variable ROI should be considered.

Impact of stroke volume on motor outcome in neonatal arterial ischemic stroke.

Neonatal arterial ischemic stroke (NAIS) can lead to long-term neurological consequences such as cerebral palsy (CP). The aim of this study was to evaluate the predictive value of acute diffusion-weighted imaging (DWI) for CP by analyzing stroke volume next to brain structure involvement. We included 37 term-born infants with NAIS prospectively registered in a nationwide pediatric stroke registry. DWI was performed between 0 and 8 days (mean 3 days) after stroke manifestation. Participants were neurologically assessed at the age of 2 years. We calculated the stroke volume (in mm3) and the ratio of the stroke volume to the volume of the entire brain (relative stroke volume). The predictive value of the relative stroke volume was analyzed and an optimal threshold for classification of children with high- and low-rates of CP was calculated. Predictive value of brain structure involvements and the prevalence of CP in combinations of different brain structures was also assessed. Sixteen children (43.2%) developed CP. Relative stroke volume significantly predicted CP (p<.001). Its optimal threshold for division into high- and low-rate of CP was 3.3%. The basal ganglia (OR 8.3, 95% CI 1.2-60.0) and basis pontis (OR 18.5, 95% CI 1.8-194.8) were independently associated with CP. In addition to determining the involvement of affected brain areas, the volumetric quantification of stroke volume allows accurate prediction of cerebral palsy in newborns with NAIS.

Automated 3-Dimensional Single-Beat Real-Time Volume Colour Flow Doppler Echocardiography in Children: A Validation Study of Right and Left Heart Flows

BackgroundNovel quantification of stroke volume according to mitral inflow and aortic outflow using automated real-time 3-dimensional volume colour flow Doppler echocardiography (3D-RT-VCFDE) is more accurate than 2-dimensional echocardiography and has excellent correlation with cardiac magnetic resonance imaging-based flows in adults. This technology is applied for the first time to the right heart and in children. Methods3D-RT-VCFDE was performed in 61 image sets of flow through the aortic (AV), mitral (MV), pulmonary (PV), and tricuspid (TV) valves of 34 children. These were compared with stroke volumes of the right (RV) and left (LV) ventricles and ratio of pulmonary to systemic blood flow determined using the Fick method in 31 children with atrial shunts. ResultsThe mean age was 8.0 ± 3.3 years, and the mean weight was 27.8 ± 10.0 kg. The mean temporal resolution for flow analyses was ≥ 22 volumes per second. In conditions with no shunt, the correlations were: AV with MV flows (r = 0.98), PV with TV flows (r = 0.96), RV stroke volume with PV flow (r = 0.95), and with TV flow (r = 0.93), LV stroke volume with AV flow (r = 0.87), and with MV flow (r = 0.89). Fick ratio of pulmonary to systemic blood flow correlations were: PV/AV ratio (r = 0.84), TV/MV ratio (r = 0.87), and RV/LV ratio (r = 0.70). ConclusionsStroke volume determined using automated 3D-RT-VCFDE is feasible in children and in the right side of the heart. This technique potentially provides a noninvasive alternative to historically invasively acquired hemodynamic data and to cardiac magnetic resonance imaging.

Continuous Rapid Quantification of Stroke Volume Using Magnetohydrodynamic Voltages in 3T Magnetic Resonance Imaging

To develop a technique to noninvasively estimate stroke volume in real time during magnetic resonance imaging (MRI)-guided procedures, based on induced magnetohydrodynamic voltages (VMHD) that occur in ECG recordings during MRI exams, leaving the MRI scanner free to perform other imaging tasks. Because of the relationship between blood flow (BF) and VMHD, we hypothesized that a method to obtain stroke volume could be derived from extracted VMHD vectors in the vectorcardiogram (VCG) frame of reference (VMHDVCG). To estimate a subject-specific BF-VMHD model, VMHDVCG was acquired during a 20-s breath-hold and calibrated versus aortic BF measured using phase-contrast magnetic resonance in 10 subjects (n=10) and 1 subject diagnosed with premature ventricular contractions. Beat-to-beat validation of VMHDVCG-derived BF was performed using real-time phase-contrast imaging in 7 healthy subjects (n=7) during 15-minute cardiac exercise stress tests and 30 minutes after stress relaxation in 3T MRIs. Subject-specific equations were derived to correlate VMHDVCG with BF at rest and validated using real-time phase-contrast. An average error of 7.22% and 3.69% in stroke volume estimation, respectively, was found during peak stress and after complete relaxation. Measured beat-to-beat BF time history derived from real-time phase-contrast and VMHD was highly correlated using a Spearman rank correlation coefficient during stress tests (0.89) and after stress relaxation (0.86). Accurate beat-to-beat stroke volume and BF were estimated using VMHDVCG extracted from intra-MRI 12-lead ECGs, providing a means to enhance patient monitoring during MR imaging and MR-guided interventions.

Motion-aware stroke volume quantification in 4D PC-MRI data of the human aorta.

4D PC-MRI enables the noninvasive measurement of time-resolved, three-dimensional blood flow data that allow quantification of the hemodynamics. Stroke volumes are essential to assess the cardiac function and evolution of different cardiovascular diseases. The calculation depends on the wall position and vessel orientation, which both change during the cardiac cycle due to the heart muscle contraction and the pumped blood. However, current systems for the quantitative 4D PC-MRI data analysis neglect the dynamic character and instead employ a static 3D vessel approximation. We quantify differences between stroke volumes in the aorta obtained with and without consideration of its dynamics. We describe a method that uses the approximating 3D segmentation to automatically initialize segmentation algorithms that require regions inside and outside the vessel for each temporal position. This enables the use of graph cuts to obtain 4D segmentations, extract vessel surfaces including centerlines for each temporal position and derive motion information. The stroke volume quantification is compared using measuring planes in static (3D) vessels, planes with fixed angulation inside dynamic vessels (this corresponds to the common 2D PC-MRI) and moving planes inside dynamic vessels. Seven datasets with different pathologies such as aneurysms and coarctations were evaluated in close collaboration with radiologists. Compared to the experts' manual stroke volume estimations, motion-aware quantification performs, on average, 1.57% better than calculations without motion consideration. The mean difference between stroke volumes obtained with the different methods is 7.82%. Automatically obtained 4D segmentations overlap by 85.75% with manually generated ones. Incorporating motion information in the stroke volume quantification yields slight but not statistically significant improvements. The presented method is feasible for the clinical routine, since computation times are low and essential parts run fully automatically. The 4D segmentations can be used for other algorithms as well. The simultaneous visualization and quantification may support the understanding and interpretation of cardiac blood flow.

Rapid quantification of stroke volume using magnetohydrodynamic voltages in 3T MRI: a feasibility study

Background The Electrocardiogram (ECG) is a standard clinical tool for cardiac physiological monitoring, required for cardiac synchronization during cardiac MRI, despite signal artifacts resulting from Magnetohydrodynamic voltages (VMHD). VMHD becomes significant during systole when rapidly ejected blood from the left ventricle into the aortic arch interacts with the strong magnetic field (B0 )o f the MRI [1]. Due to this relationship, we hypothesized that blood flow as a function of time in the cardiac cycle and left ventricular Stroke Volume (SV) could be derived using VMHD extracted from intra-MRI ECG. This method would allow for real-time beat-to-beat SV estimation during clinical MR scanning and cardiac MRI stress testing. This non-invasive real-time physiological measure of patient condition can be provided with the described software processing during conventional cardiac MRI routines, and potentially replace Invasive Blood Pressure during complex interventional procedures.

Free‐breathing phase contrast MRI with near 100% respiratory navigator efficiency using k‐space‐dependent respiratory gating

To investigate the efficacy of a novel respiratory motion scheme, where only the center of k-space is gated using respiratory navigators, versus a fully respiratory-gated acquisition for three-dimensional flow imaging. Three-dimensional flow images were acquired axially using a gradient echo sequence in a volume, covering the ascending and descending aorta, and the pulmonary artery bifurcation in 12 healthy subjects (33.2 ± 15.8 years; five men). For respiratory motion compensation, two gating and tracking strategies were used with a 7-mm gating window: (1) All of k-space acquired within the gating window (fully gated) and (2) central k-space acquired within the gating window, and the remainder of k-space acquired without any gating (center gated). Each scan was repeated twice. Stroke volume, mean flow, peak velocity, and signal-to-noise-ratio measurements were performed both on the ascending and on the descending aorta for all acquisitions, which were compared using a linear mixed-effects model and Bland-Altman analysis. There were no statistical differences between the fully gated and the center-gated strategies for the quantification of stroke volume, peak velocity, and mean flow, as well as the signal-to-noise-ratio measurements. Furthermore, the proposed center-gated strategy had significantly shorter acquisition time compared to the fully gated strategy (13:19 ± 3:02 vs. 19:35 ± 5:02, P < 0.001). The proposed novel center-gated strategy for three-dimensional flow MRI allows for markedly shorter acquisition time without any systematic variation in quantitative flow measurements in this small group of healthy volunteers.

Left Ventricular Stroke Volume Quantification by Contrast Echocardiography – Comparison of Linear and Flow‐Based Methods to Cardiac Magnetic Resonance

Echocardiography (echo)-quantified LV stroke volume (SV) is widely used to assess systolic performance after acute myocardial infarction (AMI). This study compared 2 common echo approaches - predicated on flow (Doppler) and linear chamber dimensions (Teichholz) - to volumetric SV and global infarct parameters quantified by cardiac magnetic resonance (CMR). Multimodality imaging was performed as part of a post-AMI registry. For echo, SV was measured by Doppler and Teichholz methods. Cine-CMR was used for volumetric SV and LVEF quantification, and delayed-enhancement (DE) CMR for infarct size. Overall, 142 patients underwent same day echo and CMR. On echo, mean SV by Teichholz (78±17mL) was slightly higher than Doppler (75±16mL; Δ=3±13mL; P=0.02). Compared to SV on CMR (78±18mL), mean difference by Teichholz (Δ=-0.2±14; P=0.89) was slightly smaller than Doppler (Δ=-3±14; P=0.02), but limits of agreement were similar between CMR and echo methods (Teichholz: -28, 27mL, Doppler: -31, 24mL). For Teichholz, differences with CMR SV were greatest among patients with anteroseptal or lateral wall hypokinesis (P<0.05). For Doppler, differences were associated with aortic valve abnormalities or root dilation (P=0.01). SV by both echo methods decreased stepwise in relation to global LV injury as assessed by CMR-quantified LVEF and infarct size (P<0.01). Teichholz and Doppler calculated SV yield similar magnitude of agreement with CMR. Teichholz differences with CMR increase with septal or lateral wall contractile dysfunction, whereas Doppler yields increased offsets in patients with aortic remodeling.

Design, construction, and evaluation of a dynamic MR compatible cardiac left ventricle model

Development of magnetic resonance (MR) sequences is important to answer clinical questions and to overcome current limitations. To meet the challenges of cardiac MR, dynamic and reproducible testing conditions are required. We aimed at developing a dynamic MR-compatible cardiac left ventricle model that imitates myocardial tissue properties and simulates dynamic motion. A dynamic left ventricle silicone model was designed to match myocardial T(1) and T(2) relaxation times. Silicone mixtures were explored to replicate T(2) values of myocardial edema. A controllable piston pump was constructed to produce pulsatile flow paradigms. They were validated against flow sensors and MR data, including SSFP-based and phase-contrast-based sequences. A dedicated software interface was developed for the control. Model dimensions represented cardiac left ventricle dimensions of healthy men. The range of end diastolic volumes was 85-175 ml, depending on the driven stroke volume. Stroke volume quantification for flow paradigms of 30∕60∕90∕120 ml resulted in 29.2∕57.6∕88.8∕118.4 ml by MR volumetry, 29.6∕59.9∕89.4∕119.0 ml by phase contrast measurements, and 29.9∕60.4∕91.1∕120.9 ml by flow meter revealing consistency. The system accurately replicated physiological and pathophysiological flow paradigms. The silicon model exhibited T(1) of 1002 ± 8 ms, T(2) of 58 ± 1 ms. Signal intensities (a.u.) of the ventricle model were 128 ± 23 for FGRE (vs 138 ± 17 in vivo) and 1156 ± 37 for b-SSFP (vs 991 ± 96 in vivo). T(2) of 75 ± 2 ms was achieved for the myocardial pathology. We developed a controllable left ventricle model resembling MR signal characteristics of human myocardium, including pathological conditions, and allowing for the replication of contraction and flow paradigms.

Effect of Dynamic Flow Rate and Orifice Area on Mitral Regurgitant Stroke Volume Quantification Using the Proximal Isovelocity Surface Area Method

This study sought to determine the effect of dynamic variations of mitral regurgitant flow rate (MRFR) and effective regurgitant orifice area (EROA) on mitral regurgitant stroke volume (MRSV) quantification using 4 different single-point and time-integral proximal isovelocity surface area (PISA) methods using magnetic resonance imaging (MRI) for reference. Using PISA provides measures of MRFR, but calculating MRSV is challenging because of dynamic variations in the flow profile dependent on the underlying mechanism of mitral regurgitation (MR). Although various single-point and time-integral approaches have been described to overcome this limitation, uncertainty exists about the accuracy and feasibility of these methods in routine clinical practice. In 73 patients with MR of different etiologies, MRSV was calculated from an apical 4-chamber view using the following 4 hemispheric PISA methods: 1) PISA-velocity-time integral (VTI) = midsystolic MRFR by PISA x regurgitant flow VTI/peak velocity; 2) simplified PISA = midsystolic MRFR/3.25; 3) serial PISA = sum of instantaneous MRFRs over serial 2-dimensional frames; and 4) M-mode PISA = time-integral of MRFRs from color M-mode. The MRSV by MRI was calculated from mitral inflow minus aortic outflow. Single-point PISA methods yielded greater underestimation of MRSV (mean error: -13.3 +/- 10.2 ml [PISA-VTI]; -13.5 +/- 10.3 ml [simplified PISA]), particularly in functional MR, compared with time-integral PISA methods accounting for variations of MRFR and EROA over time (mean error: -8.0 +/- 6.4 ml [M-mode PISA]; -8.7 +/- 7.4 ml [serial PISA]). Depending on the underlying mechanism of MR, dynamic variations of MRFR and EROA revealed important limitations of MRSV calculation using single-point and time-integral PISA methods.

Evaluation of accordance of magnetic resonance volumetric and flow measurements in determining ventricular stroke volume in cardiac patients

Cardiovascular magnetic resonance imaging (CMR) has become an established noninvasive method for evaluating ventricular function utilizing three-dimensional volumetry. Postprocessing of volumetric measurements is still tedious and time consuming. Stroke volumes obtained by flow quantification across the aortic root or pulmonary trunk could be utilized to increase both speed of workflow and accuracy. To assess accuracy of stroke volume quantification using MR volumetric imaging compared to flow quantification in patients with various cardiac diseases. Strategies for the augmentation of accuracy in clinical routine were deduced. 78 patients with various cardiac diseases-excluding intra- or extracardiac shunts, regurgitant valvular defects, or heart rhythm disturbance-underwent cardiac function analysis with flow measurements across the aortic root and cine imaging of the left ventricle. Forty-six patients additionally underwent flow measurements in the pulmonary trunk and cine imaging of the right ventricle. Left ventricular stroke volume (LVSV) and stroke volume of the aortic root (SVAo) correlated with r=0.97, and Bland-Altman analysis showed a mean difference of 0.11 ml and a standard error of estimation (SEE) of 4.31 ml. Ninety-two percent of the data were within the 95% limits of agreement. Right ventricular stroke volume (RVSV) and stroke volume of the pulmonary trunk (SVP) correlated with a factor of r=0.86, and mean difference in the Bland-Altman analysis was fixed at -2.62 ml (SEE 8.47 ml). For RVSV and SVP, we calculated r=0.82, and Bland-Altman analysis revealed a mean difference of 1.27 ml (SEE 9.89 ml). LVSV and RVSV correlated closely, with r=0.91 and a mean difference of 2.79 ml (SEE 7.17 ml). SVAo and SVP correlated with r=0.95 and a mean difference of 0.50 ml (SEE 5.56 ml). Flow quantification can be used as a guidance tool, providing accurate and reproducible stroke volumes of both ventricles. Combining both offers a highly accurate tool to gauge ventricular function in a routine clinical setting, increasing workflow speed.

Quantification of gastric emptying and duodenogastric reflux stroke volumes using three-dimensional guided digital color Doppler imaging

Objective: To develop a non-invasive method for evaluating gastric emptying and duodenogastric reflux stroke volumes using three-dimensional (3D) guided digital color Doppler imaging. Methods: The technique involved color Doppler digital images of transpyloric flow in which the 3D position and orientation of the images were known by using a magnetic location system. Results: In vitro, the system was found to slightly underestimate the reference flow (by average 8.8%). In vivo (five volunteers), stroke volume of gastric emptying episodes lasted on average only 0.69 s with a volume on average of 4.3 ml (range 1.1–7.4 ml), and duodenogastric reflux episodes on average 1.4 s with a volume of 8.3 ml (range 1.3–14.1 ml). Conclusion: With the appropriate instrument settings, orientation determined color Doppler can be used for stroke volume quantification of gastric emptying and duodenogastric reflux episodes.

Three-dimensional echocardiography. In vivo validation for left ventricular volume and function.

Current two-dimensional quantitative echocardiographic methods of volume assessment require image acquisition from standardized scanning planes. Left ventricular volume and ejection fraction are then calculated by assuming ventricular symmetry and geometry. These assumptions may not be valid in distorted ventricles. Three-dimensional echocardiography can quantify left ventricular volume without the limitations imposed by the assumptions of two-dimensional methods. We have developed a three-dimensional system that automatically integrates two-dimensional echocardiographic images and their positions in real time and calculates left ventricular volume directly from traced endocardial contours without geometric assumptions. To study the accuracy of this method in quantifying left ventricular volume and performance in vivo, a canine model was developed in which instantaneous left ventricular volume can be measured directly with an intracavitary balloon connected to an external column. Ten dogs were studied at 84 different cavity volumes (4 to 85 cm3) and in conditions of altered left ventricular shape produced by either coronary occlusion or right ventricular volume overload. To demonstrate clinical feasibility, 19 adult human subjects were then studied by this method for quantification of stroke volume. Left ventricular volume, stroke volume, and ejection fraction calculated by three-dimensional echocardiography correlated well with directly measured values (r = .98, .96, .96 for volume, stroke volume, and ejection fraction, respectively) and agreed closely with them (mean difference, -0.78 cm3, -0.60 cm3, -0.32%). In humans, there was a good correlation (r = .94, SEE = 4.29 cm3) and agreement (mean difference, -0.98 +/- 4.2 cm3) between three-dimensional echocardiography and Doppler-derived stroke volumes. Three-dimensional echocardiography allows accurate assessment of left ventricular volume and systolic function.