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ASE Young Investigator’s Award Finalists 2006
Journal of the American Society of Echocardiography Volume 20 Number 5
Abstracts 555
2007 Arthur E. Weyman Young Investigator’s Award Finalists Tuesday, June 19, 2007: Presented 8 AM – 9:30 AM Ra
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Estimation of Lagrangian Strain and Rotation Using a New Algorithm Based on Speckle Tracking
Load Dependency of Mitral Annulus Velocities, Strain and Strain Rates Evaluated by Parabolic Flight
Francois B Tournoux1, Raymond C Chan2, Mark D Handscumacher1, Ivan Salgo3, Robert Manzke2, Ricardo Cury1, Arthur E Weyman1, Michael H Picard1 1 Massachusetts General Hospital, Boston, MA; 2Philips Research North America, Boston, MA; 3Philips Medical Systems, Andover, MA
Enrico G Caiani1, Lynn Weinert2, Masaki Takeuchi3, Federico Veronesi1, Lissa Sugeng2, Cristiana Corsi4, André Capderou5, Pierre Vaida6, Roberto M Lang2 1 Politecnico di Milano, Milano, Italy; 2University of Chicago, Chicago, IL; 3Tane General Hospital, Osaka, Japan; 4University of Bologna, Bologna, Italy; 5Université Paris Sud, Le Plessis Robinson, France; 6University of Bordeaux 2, Bordeaux, France
Background. Speckle tracking (SpT) allows for frame-by-frame estimation of specific tissue motion patterns within a grey-scale image. Current algorithms based on this method estimate myocardial deformation within a region of interest (ROI) and are sensitive to myocardium’s borders definition. A new approach based on change in distance between two distinct ROIs manually operator selected should allow computation of Lagrangian strain (LS) in any desired zone of the myocardium. Similarly, tracking of a ROI excursion relative to a fixed point should allow estimation of rotation (ROT). Methods. A dynamic polyvinyl alcohol phantom model (60 beats/min) was scanned using a 2.5 MHz probe (IE 33, Philips) at frame rates of 30, 60 and 90 Hz. To estimate LS, two ROIs were drawn in a short-axis view on the border on either side of the superior wall and tracked using SpT over 3 consecutive pulsatile cycles. The initial distance D(0) and changes in the distance between the two ROIs (D(t)-D(0)) were measured to calculate transmural LS: [D(t)-D(0)]/D(0). Measurements were compared with reference LS from sonomicrometers (SN) (Sonometrics Corp.). To estimate ROT, 3 epicardial sapphire beads were tracked using SpT. Reference points were initial position of the bead and center of the phantom. Measurements were compared with reference ROT from multi-slice cardiac CT imaging. Results. There was a significant correlation between SpT-LS and SN-LS for frame rates of 30 Hz (R2=0.94, P<0.0001), 60 Hz (R²=0.99, P<0.0001) and 90 Hz (R²=0.98, P<0.0001). Similarly, there was a significant correlation between SpT-ROT and CT-ROT: R²=0.83 with P<0.0001 at 30 Hz, R²=0.96 with P<0.0001 at 60 Hz and R²=0.96 with P<0.0001 at 90 Hz. Regression lines are shown for 60 Hz. Mean of error from Bland and Altman representation for LS and ROT were -1.6±1.5% and 1.2±0.7° respectively. Conclusion. Assessment of change in distance between two distinct tissue regions allows for simple and accurate LS assessment that agrees well with a reference measurement. Similarly, tracking the position of a single ROI relative to a reference point allows accurate estimation of its ROT. This LS index and ROT can be derived from short axis views independent of angle and without the need for border detection of the entire chamber.
Doppler tissue echocardiography (DTE) is routinely used to assess regional left ventricular (LV) function by measuring tissue velocities, strain (ε) and strain rates (SR). However, the preload dependency of these parameters remains controversial. Our aim was to test the hypothesis that tissue velocities, ε and SR measured by DTE are preload dependent in normal subjects (N). To change preload, parabolic flights were used because: a) they generate abrupt changes in hydrostatic pressure gradients; b) both reductions and increases in preload can be induced using the same experimental settings; c) imaging can be performed immediately following the preload changes; d) load changes can be performed reliably in a repeated fashion. We studied the effects on DTE parameters of acute preload reduction during hypergravity (1.8Gz), and of acute preload increase during microgravity (0Gz). Moreover, lower body negative pressure (LBNP) applied during 0 Gz allowed us to investigate the effects of preload reduction without any intraventricular hydrostatic pressure gradient. Methods. DTE and real-time 3D echocardiographic images (Philips) were obtained in 10 N in standing position at 1Gz, 1.8Gz and 0Gz, with and without -50mmHg LBNP. Myocardial velocity curves in the basal inter-ventricular septum were calculated offline, from which peak systolic (S’), early (E’) and late (A’) diastolic velocities, SR and peak systolic strain (PSε) were measured and averaged over four beats. Results. Compared to 1Gz, during 1.8Gz LV EDV and SV decreased by 21% and 27%, respectively, while ESV and EF were unchanged; S’, E’ and A’ decreased by 21%, 21% and 26%, respectively. At 0Gz, EDV, ESV and SV increased by 23%, 10% and 34%, respectively, compared to 1Gz; E’, A’ and PSe increased by 57%, 53% and 49%, respectively. With LBNP at 0Gz, EDV and SV were restored to 1Gz values, while E’ and PSε were reduced compared to 0Gz. Conclusion. Regional longitudinal myocardial tissue contraction and relaxation velocities and PSε in N were found preload dependent. Our findings support the hypothesis that S’ SR is a preload-independent index of contractile function, while SR E’ and SR A’ reflect more complex interactions between myocardial properties and loading conditions. These findings should be considered when using DTE in clinical practice.
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Impact of Intraventricular Blood Flow Vorticity on Left Ventricular Function in Normals and Patients with Heart Failure: Quantitative Assessment by Contrast Echocardiography Using Vector Particle Image Velocitimetry
Molecular Imaging of Inflammation in Atherosclerotic Lesions: A Potential Method for Early Detection and Risk Assessment
Geu-Ru Hong1, Peng Li1, Gianni Pedrizzetti2, Federico Domenichini3, Wei Zhao1, Shannon Jin1, Helene Houle4, Jagat Narula1, Mani Vannan1 1 University of California, Irvine, Orange, CA; 2University of Trieste, Trieste, Italy; 3 University of Firenze, Firenze, Italy; 4Siemens Medical Solutions, Mountain View, CA Background: Intraventricular blood flow is optimized to facilitate efficient systolic ejection of blood. Vortices that form during LV filling have specific geometry and anatomical location which are critical determinants of directed blood flow during ejection. The aims of this study were 1) to quantify LV vortex flow by contrast echocardiography (CE) in normals and patients with LV systolic dysfunction, and 2) to evaluate the impact of quantitative LV vortex flow parameters on the hemodynamic performance of the LV. Methods: 25 patients (10 normals and 8 with dilated cardiomyopathy (CM) and 7 with ischemic CM) underwent 2-D CE with 0.10.2 ml of iv Definity and imaged at an MI index of 0.3-0.5 in the A4C and APLX views. The x and y components of the velocity vector and vorticity on the scan-plane were estimated by particle image velocitimetry (PIV), combined with a Feature Tracking Algorithm (FTA). Average vortex depth, length, width (VD, VL, VW, unitless) relative to total LV length and sphericity index (SI) were measured. Relative Strength (RS, unitless) which represents pulsatility of vortex was also estimated. Results:. LV EF (31.7% ± 17.5 Vs. 64.4% ± 6.6 p<0.001) and cardiac output (3.6 L/min ± 1.5 Vs. 5.3 L/ min ± 1.4 p<0.001) were lower in abnormal LV group. LV end diastolic dimension was greater (56.7 ± 8.5 Vs. 46.5 ± 7.6 p=0.009) in abnormal LV group. Average VD and VL were decreased ( 0.443 ± 0.02 Vs. 0.482 ± 0.04 p = 0.006; 0.366 ± 0.02 Vs. 0.467 ± 0.02 p < 0.001 respectively) in LV dysfunction group. Average VW was greater (0.209 ± 0.05 Vs. 0.128 ± 0.01 p< 0.001) and SI was lower (1.86 ± 0.5 Vs. 3.66 ± 0.9 p < 0.001) in LV dysfunction group. RS was lower (0.85 ± 0.3 Vs. 1.63 ± 0.5 p < 0.001) in the abnormal LV function group compare to normals. Figure shows parametric representations of 1) steady streaming field with superimposed velocity vectors (arrows) in-plane streamlines (A), and 2) the pulsatile strength field with superimposed the pulsatile in-plane streamlines (B). Conclusion: The data from this preliminary study show that 1) It is feasible to quantify LV vorticity by CE using PIV and 2) These measures may determine the LV cardiac output even in the setting of dilated chamber in patients with heart failure and contribute to resting symptomatic status of these patients. Further confirmatory studies are necessary.
Beat A Kaufmann1, John M Sanders2, Christopher Davis2, Aris Xie1, Ian J Sarembock2, Jonathan R Lindner1 1 Oregon Health & Science University, Portland, OR; 2University of Virginia, Charlottesville, VA OBJECTIVES: The ability to image vascular inflammatory responses may allow very early diagnosis and treatment of atherosclerosis. We hypothesized that molecular imaging of VCAM1 expression with contrast-enhanced ultrasound (CEU) could be used for this purpose. METHODS: Attachment of VCAM-1-targeted (MBV) and control microbubbles (MBC) to cultured endothelial cells was assessed in a flow chamber at variable shear rates (0.5-12.0 dyne/ cm2). Microbubble attachment to plaque in vivo was determined by fluorescent microscopy of the thoracic aorta 10 min after intravenous injection of fluorescently labeled microbubbles in wild-type or ApoE-deficient mice, on either chow or hypercholesterolemic diet (HCD) (n=3-4 per group). CEU molecular imaging of the thoracic aorta 10 min after intravenous microbubble injection was performed for the same 4 animal groups (n=9-11 per group). RESULTS: VCAM-1-targeted but not control microbubbles attached to cultured endothelial cells, although firm attachment at the highest shear rates (8-12 dyne/cm2) occurred only under pulsatile flow conditions produced by brief reductions of shear. Aortic attachment of MBC was low in all 4 groups, whereas attachment for MBV was significantly higher than MBC in all groups except wild type mice on chow and increased in a stepwise fashion from wild type mice on HCD and ApoE-/- mice on chow to ApoE-/- on HCD. Similarly, targeted CEU signal was low for MBC in all four animal groups (wild type on chow 2.3±3.1; wild type on HCD 1.8±2.2; ApoE-/- on chow 1.6±2.0; ApoE-/- on HCD 1.0±1.5; ANOVA p=ns). Targeted CEU signal from MBV was significantly larger than signal from MBC in all groups except wild type mice on chow and increased in a stepwise fashion (wild type on chow 2.0±1.0; wild type on HCD 5.1±3.3; ApoE-/- on chow 5.7±2.6; ApoE-/- on HCD 12.2±4.4; ANOVA p<0.005). Signal for MBV in ApoE-/- mice on HCD was significantly higher than in all other groups (p<0.001), and for Apo E-/- on chow was significantly higher than for wild type mice on chow (p<0.05). The 4 animal groups also had a stepwise increase in plaque severity and VCAM-1 staining on histology. CONCLUSIONS: CEU molecular imaging of VCAM-1 can quantify vascular inflammatory changes that occur in different stages of atherosclerosis. Targeted CEU is a rapid and highsensitivity method for evaluation of endothelial phenotype making it ideal for early detection and risk stratification of atherosclerosis in patients.
Abstracts 555
2007 Arthur E. Weyman Young Investigator’s Award Finalists Tuesday, June 19, 2007: Presented 8 AM – 9:30 AM Ra
Rb
Estimation of Lagrangian Strain and Rotation Using a New Algorithm Based on Speckle Tracking
Load Dependency of Mitral Annulus Velocities, Strain and Strain Rates Evaluated by Parabolic Flight
Francois B Tournoux1, Raymond C Chan2, Mark D Handscumacher1, Ivan Salgo3, Robert Manzke2, Ricardo Cury1, Arthur E Weyman1, Michael H Picard1 1 Massachusetts General Hospital, Boston, MA; 2Philips Research North America, Boston, MA; 3Philips Medical Systems, Andover, MA
Enrico G Caiani1, Lynn Weinert2, Masaki Takeuchi3, Federico Veronesi1, Lissa Sugeng2, Cristiana Corsi4, André Capderou5, Pierre Vaida6, Roberto M Lang2 1 Politecnico di Milano, Milano, Italy; 2University of Chicago, Chicago, IL; 3Tane General Hospital, Osaka, Japan; 4University of Bologna, Bologna, Italy; 5Université Paris Sud, Le Plessis Robinson, France; 6University of Bordeaux 2, Bordeaux, France
Background. Speckle tracking (SpT) allows for frame-by-frame estimation of specific tissue motion patterns within a grey-scale image. Current algorithms based on this method estimate myocardial deformation within a region of interest (ROI) and are sensitive to myocardium’s borders definition. A new approach based on change in distance between two distinct ROIs manually operator selected should allow computation of Lagrangian strain (LS) in any desired zone of the myocardium. Similarly, tracking of a ROI excursion relative to a fixed point should allow estimation of rotation (ROT). Methods. A dynamic polyvinyl alcohol phantom model (60 beats/min) was scanned using a 2.5 MHz probe (IE 33, Philips) at frame rates of 30, 60 and 90 Hz. To estimate LS, two ROIs were drawn in a short-axis view on the border on either side of the superior wall and tracked using SpT over 3 consecutive pulsatile cycles. The initial distance D(0) and changes in the distance between the two ROIs (D(t)-D(0)) were measured to calculate transmural LS: [D(t)-D(0)]/D(0). Measurements were compared with reference LS from sonomicrometers (SN) (Sonometrics Corp.). To estimate ROT, 3 epicardial sapphire beads were tracked using SpT. Reference points were initial position of the bead and center of the phantom. Measurements were compared with reference ROT from multi-slice cardiac CT imaging. Results. There was a significant correlation between SpT-LS and SN-LS for frame rates of 30 Hz (R2=0.94, P<0.0001), 60 Hz (R²=0.99, P<0.0001) and 90 Hz (R²=0.98, P<0.0001). Similarly, there was a significant correlation between SpT-ROT and CT-ROT: R²=0.83 with P<0.0001 at 30 Hz, R²=0.96 with P<0.0001 at 60 Hz and R²=0.96 with P<0.0001 at 90 Hz. Regression lines are shown for 60 Hz. Mean of error from Bland and Altman representation for LS and ROT were -1.6±1.5% and 1.2±0.7° respectively. Conclusion. Assessment of change in distance between two distinct tissue regions allows for simple and accurate LS assessment that agrees well with a reference measurement. Similarly, tracking the position of a single ROI relative to a reference point allows accurate estimation of its ROT. This LS index and ROT can be derived from short axis views independent of angle and without the need for border detection of the entire chamber.
Doppler tissue echocardiography (DTE) is routinely used to assess regional left ventricular (LV) function by measuring tissue velocities, strain (ε) and strain rates (SR). However, the preload dependency of these parameters remains controversial. Our aim was to test the hypothesis that tissue velocities, ε and SR measured by DTE are preload dependent in normal subjects (N). To change preload, parabolic flights were used because: a) they generate abrupt changes in hydrostatic pressure gradients; b) both reductions and increases in preload can be induced using the same experimental settings; c) imaging can be performed immediately following the preload changes; d) load changes can be performed reliably in a repeated fashion. We studied the effects on DTE parameters of acute preload reduction during hypergravity (1.8Gz), and of acute preload increase during microgravity (0Gz). Moreover, lower body negative pressure (LBNP) applied during 0 Gz allowed us to investigate the effects of preload reduction without any intraventricular hydrostatic pressure gradient. Methods. DTE and real-time 3D echocardiographic images (Philips) were obtained in 10 N in standing position at 1Gz, 1.8Gz and 0Gz, with and without -50mmHg LBNP. Myocardial velocity curves in the basal inter-ventricular septum were calculated offline, from which peak systolic (S’), early (E’) and late (A’) diastolic velocities, SR and peak systolic strain (PSε) were measured and averaged over four beats. Results. Compared to 1Gz, during 1.8Gz LV EDV and SV decreased by 21% and 27%, respectively, while ESV and EF were unchanged; S’, E’ and A’ decreased by 21%, 21% and 26%, respectively. At 0Gz, EDV, ESV and SV increased by 23%, 10% and 34%, respectively, compared to 1Gz; E’, A’ and PSe increased by 57%, 53% and 49%, respectively. With LBNP at 0Gz, EDV and SV were restored to 1Gz values, while E’ and PSε were reduced compared to 0Gz. Conclusion. Regional longitudinal myocardial tissue contraction and relaxation velocities and PSε in N were found preload dependent. Our findings support the hypothesis that S’ SR is a preload-independent index of contractile function, while SR E’ and SR A’ reflect more complex interactions between myocardial properties and loading conditions. These findings should be considered when using DTE in clinical practice.
Rc
Rd
Impact of Intraventricular Blood Flow Vorticity on Left Ventricular Function in Normals and Patients with Heart Failure: Quantitative Assessment by Contrast Echocardiography Using Vector Particle Image Velocitimetry
Molecular Imaging of Inflammation in Atherosclerotic Lesions: A Potential Method for Early Detection and Risk Assessment
Geu-Ru Hong1, Peng Li1, Gianni Pedrizzetti2, Federico Domenichini3, Wei Zhao1, Shannon Jin1, Helene Houle4, Jagat Narula1, Mani Vannan1 1 University of California, Irvine, Orange, CA; 2University of Trieste, Trieste, Italy; 3 University of Firenze, Firenze, Italy; 4Siemens Medical Solutions, Mountain View, CA Background: Intraventricular blood flow is optimized to facilitate efficient systolic ejection of blood. Vortices that form during LV filling have specific geometry and anatomical location which are critical determinants of directed blood flow during ejection. The aims of this study were 1) to quantify LV vortex flow by contrast echocardiography (CE) in normals and patients with LV systolic dysfunction, and 2) to evaluate the impact of quantitative LV vortex flow parameters on the hemodynamic performance of the LV. Methods: 25 patients (10 normals and 8 with dilated cardiomyopathy (CM) and 7 with ischemic CM) underwent 2-D CE with 0.10.2 ml of iv Definity and imaged at an MI index of 0.3-0.5 in the A4C and APLX views. The x and y components of the velocity vector and vorticity on the scan-plane were estimated by particle image velocitimetry (PIV), combined with a Feature Tracking Algorithm (FTA). Average vortex depth, length, width (VD, VL, VW, unitless) relative to total LV length and sphericity index (SI) were measured. Relative Strength (RS, unitless) which represents pulsatility of vortex was also estimated. Results:. LV EF (31.7% ± 17.5 Vs. 64.4% ± 6.6 p<0.001) and cardiac output (3.6 L/min ± 1.5 Vs. 5.3 L/ min ± 1.4 p<0.001) were lower in abnormal LV group. LV end diastolic dimension was greater (56.7 ± 8.5 Vs. 46.5 ± 7.6 p=0.009) in abnormal LV group. Average VD and VL were decreased ( 0.443 ± 0.02 Vs. 0.482 ± 0.04 p = 0.006; 0.366 ± 0.02 Vs. 0.467 ± 0.02 p < 0.001 respectively) in LV dysfunction group. Average VW was greater (0.209 ± 0.05 Vs. 0.128 ± 0.01 p< 0.001) and SI was lower (1.86 ± 0.5 Vs. 3.66 ± 0.9 p < 0.001) in LV dysfunction group. RS was lower (0.85 ± 0.3 Vs. 1.63 ± 0.5 p < 0.001) in the abnormal LV function group compare to normals. Figure shows parametric representations of 1) steady streaming field with superimposed velocity vectors (arrows) in-plane streamlines (A), and 2) the pulsatile strength field with superimposed the pulsatile in-plane streamlines (B). Conclusion: The data from this preliminary study show that 1) It is feasible to quantify LV vorticity by CE using PIV and 2) These measures may determine the LV cardiac output even in the setting of dilated chamber in patients with heart failure and contribute to resting symptomatic status of these patients. Further confirmatory studies are necessary.
Beat A Kaufmann1, John M Sanders2, Christopher Davis2, Aris Xie1, Ian J Sarembock2, Jonathan R Lindner1 1 Oregon Health & Science University, Portland, OR; 2University of Virginia, Charlottesville, VA OBJECTIVES: The ability to image vascular inflammatory responses may allow very early diagnosis and treatment of atherosclerosis. We hypothesized that molecular imaging of VCAM1 expression with contrast-enhanced ultrasound (CEU) could be used for this purpose. METHODS: Attachment of VCAM-1-targeted (MBV) and control microbubbles (MBC) to cultured endothelial cells was assessed in a flow chamber at variable shear rates (0.5-12.0 dyne/ cm2). Microbubble attachment to plaque in vivo was determined by fluorescent microscopy of the thoracic aorta 10 min after intravenous injection of fluorescently labeled microbubbles in wild-type or ApoE-deficient mice, on either chow or hypercholesterolemic diet (HCD) (n=3-4 per group). CEU molecular imaging of the thoracic aorta 10 min after intravenous microbubble injection was performed for the same 4 animal groups (n=9-11 per group). RESULTS: VCAM-1-targeted but not control microbubbles attached to cultured endothelial cells, although firm attachment at the highest shear rates (8-12 dyne/cm2) occurred only under pulsatile flow conditions produced by brief reductions of shear. Aortic attachment of MBC was low in all 4 groups, whereas attachment for MBV was significantly higher than MBC in all groups except wild type mice on chow and increased in a stepwise fashion from wild type mice on HCD and ApoE-/- mice on chow to ApoE-/- on HCD. Similarly, targeted CEU signal was low for MBC in all four animal groups (wild type on chow 2.3±3.1; wild type on HCD 1.8±2.2; ApoE-/- on chow 1.6±2.0; ApoE-/- on HCD 1.0±1.5; ANOVA p=ns). Targeted CEU signal from MBV was significantly larger than signal from MBC in all groups except wild type mice on chow and increased in a stepwise fashion (wild type on chow 2.0±1.0; wild type on HCD 5.1±3.3; ApoE-/- on chow 5.7±2.6; ApoE-/- on HCD 12.2±4.4; ANOVA p<0.005). Signal for MBV in ApoE-/- mice on HCD was significantly higher than in all other groups (p<0.001), and for Apo E-/- on chow was significantly higher than for wild type mice on chow (p<0.05). The 4 animal groups also had a stepwise increase in plaque severity and VCAM-1 staining on histology. CONCLUSIONS: CEU molecular imaging of VCAM-1 can quantify vascular inflammatory changes that occur in different stages of atherosclerosis. Targeted CEU is a rapid and highsensitivity method for evaluation of endothelial phenotype making it ideal for early detection and risk stratification of atherosclerosis in patients.