50 research outputs found
Quantitative 3·D Echocardiography of The Heart and The Coronary Vessels
The recognition of the existence of ultrasound
is credited to L. Spallanzani (1729-
1799). In recent years, ultrasound has been
used as an imaging modality in medicine. I.
Edler and C.H. Hertz produced the first
ultrasound images of the heart in 1953. In
the 1960's great progress was made in the
clinical application of ultrasound when
real-time two-dimensional ultrasound scanners
were developed. In 1968, J. Somer
constructed the first electronic phased-array
scanner and this technology is still the most
widely used in ultrasound equipment. In
1974 F.E. Barber and colleagues produced a
duplex scanner which integrated imaging
with pulsed-wave Doppler measurements.
C. Kasai and colleagues constmcted in
1982 the color-coded Doppler flow imaging
system based on autocorrelation detection,
providing a noninvasive "angiogram" simulation
of normal and abnormal blood flow
on a "beat-to-beat" basis. Transesophageal
echocardiography became available to clinicians
in 1985 due to the developments of
1. Soquet who invented the mono- and biplane
electronic phased-array probel
Echocardiography has become one of the
most commonly used diagnostic imaging
techniques in cardiology.
The development of commercial 3-D
echocardiographic equipment began in the
early 1990's. In 1993 a technique allowing
acquisition of tomographic parallel sliced
data set of echocardiographic images of the
heart with a lobster tail TEE probe, was
2
developed by the German based company
"TomTec GmbH". The TEE probe had an
imaging element which could be controlled
by computer applying a stepping motor.
They also developed an interface to the
patient to record the respiration and R-R
intervals. This allowed the acquisition of
ultrasound images ECG-triggered and
gated, which reduced motion artifacts caused
by beat-to-beat and respiratory variations
in cardiac dimensions and position.
After the acquisition of a tomographic data
set, the images were post-processed and
with application of software interpolation
algorithms, gaps in the data set could be filled.
This post-processed data set could then
be used to reconstruct 3-D volume rendered
images of the heart. 3-D ultrasound provides
cardiac images which more closely
mimic actual anatomy'than 2-D cross-sectional
linages, and may thus be easier to
interpret
Dynamic Three-Dimensional Echocardiography Offers Advantages for Specific Site Pacing
We have developed a novel technique for specific site pacing
Adjustment method for mechanical Boston scientific corporation 30 MHz intravascular ultrasound catheters connected to a Clearview console. Mechanical 30 MHz IVUS catheter adjustment.
Intracoronary ultrasound (ICUS) is often used in studies evaluating new interventional techniques. It is important that quantitative measurements performed with various ICUS imaging equipment and materials are comparable. During evaluation of quantitative coronary ultrasound (QCU) software, it appeared that Boston Scientific Corporation (BSC) 30 MHz catheters connected to a Clearview ultrasound console showed smaller dimensions of an in vitro phantom model than expected. In cooperation with the manufacturer the cause of this underestimation was determined, which is described in this paper, and the QCU software was extended with an adjustment. Evaluation was performed by performing in vitro measurements on a phantom model consisting of four highly accurate steel rings (perfect reflectors) with diameters of 2, 3, 4 and 5 mm. Relative differences (unadjusted) of the phantom were respectively: 15.92, 13.01, 10.10 and 12.23%. After applying the adjustment: -0.96, -1.84, -1.35 and -1.43%. In vivo measurements were performed on 24 randomly selected ICUS studies. These showed differences for not adjusted vs. adjusted measurements of lumen-, vessel- and plaque volumes of -10.1 +/- 1.5, -6.7 +/- 0.9 and -4.4 +/- 0.6%. An off-line adjustment formula was derived and applied on previous numerical QCU output data showing relative differences for lumen- and vessel volumes of 0.36 +/- 0.51 and 0.13 +/- 0.31%. 30 MHz BSC catheters connected to a Clearview ultrasound console underestimate vessel dimensions. This can retrospectively be adjusted within QCU software as well as retrospectively on numerical QCU data using a mathematical model
In vivo variability in quantitative coronary ultrasound and tissue characterization measurements with mechanical and phased-array catheters
Background: Both mechanical and phased-array catheters are used in clinical trials to assess quantitative parameters. Only limited evaluation of the in vivo agreement of volumetrical measurements between such systems has been performed, despite the fact that such information is essential for the conduction of atherosclerosis regression trials. Methods and results: We prospectively evaluated the agreement in morphometric measurements and intravascular ultrasound (IVUS)-based plaque characterization between a 40 MHz rotating transducer (3.2 F Atlantis, Boston Scientific Corp.) and a 20 MHz phased-array catheter (2.9 F Eagle Eye, Volcano Therapeutics, Rancho Cordova, California) in 16 patients. Lumen (7.3 ± 2.0 mm2 vs. 6.7 ± 1.8 mm2, p = 0.001) and vessel (11.8 ± 3.3 mm2 vs. 11.0 ± 2.9 mm2, p = 0.02) cross-sectional areas (CSA) were significantly greater with the 20 MHz system. Plaque CSA measurements showed no significant difference between systems (4.4 ± 2.3 mm2 vs. 4.4 ± 2.1). The relative differences were less than 10% for the three variables. On IVUS-based tissue characterization (13 patients), calculated percentage hypoechogenic volume was significantly higher for the 20 MHz system (96.7 ± 2.38 vs. 88.4 ± 5.53, p < 0.0001). Conclusions: Quantitative IVUS analyses display significant catheter type-dependent variability. It is unclear whether the variability reflects overestimation of measurements with the phased-array or underestimation with the mechanical system. Although plaque burden measurements did not differ significantly between systems, it appears prudent to recommend the use of a single system for progression/ regression studies
Influence of intracoronary attenuation on coronary plaque measurements using multislice computed tomography: Observations in an ex vivo model of coronary computed tomography angiography
Assessment of attenuation (measured in Hounsfield units, HU) of human coronary plaques was performed using multislice computed tomography (MSCT) in an ex vivo model. In three ex vivo specimens of left coronary arteries in oil, MSCT was performed after intracoronary injection of four solutions of contrast material (400 mgI/ml iomeprol). The four solutions were diluted as follows: 1/∞, 1/200, 1/80, and 1/20. All scans were performe
Timing of pulmonary valve replacement in patients with corrected Fallot to prevent QRS prolongation
OBJECTIVES: Timing of pulmonary valve replacement (PVR) remains one of the most heavily debated topics in congenital cardiac surgery. We aimed to analyse the temporal evolution of QRS duration before and after PVR. METHODS: We included 158 consecutive patients who underwent PVR after previous correction with transannular patch. All 3549 available serial standard 12-lead surface QRS measurements of 158 (100%) patients were analysed with linear mixed-effect modelling. RESULTS: PVR was perfo
Optical Coherence Tomography: Potential Clinical Applications
Optical coherence tomography (OCT) is a novel intravascular imaging modality using near-infrared light. By OCT it is possible to obtain high-resolution cross-sectional images of the vascular wall structure and assess the acute and long-term effects of percutaneous coronary intervention. For the time being OCT has been mainly used in research providing new insights into the pathophysiology of the atheromatic plaque and of the vascular res
ECG-Gated Three-dimensional Intravascular Ultrasound
Background Automated systems for the quantitative analysis of three-dimensional (3D) sets of intravascular ultrasound (IVUS) images have been developed to reduce the time required to perform volumetric analyses; however, 3D image reconstruction by these nongated systems is frequently hampered by cyclic artifacts.
Methods and Results We used an ECG-gated 3D IVUS image acquisition workstation and a dedicated pullback device in atherosclerotic coronary segments of 30 patients to evaluate (1) the feasibility of this approach of image acquisition, (2) the reproducibility of an automated contour detection algorithm in measuring lumen, external elastic membrane, and plaque+media cross-sectional areas (CSAs) and volumes and the cross-sectional and volumetric plaque+media burden, and (3) the agreement between the automated area measurements and the results of manual tracing. The gated image acquisition took 3.9±1.5 minutes. The length of the segments analyzed was 9.6 to 40.0 mm, with 2.3±1.5 side branches per segment. The minimum lumen CSA measured 6.4±1.7 mm2, and the maximum and average CSA plaque+media burden measured 60.5±10.2% and 46.5±9.9%, respectively. The automated contour-detection required 34.3±7.3 minutes per segment. The differences between these measurements and manual tracing did not exceed 1.6% (SD<6.8%). Intraobserver and interobserver differences in area measurements (n=3421; r=.97 to.99) were <1.6% (SD<7.2%); intraobserver and interobserver differences in volumetric measurements (n=30; r=.99) were <0.4% (SD<3.2%).
Conclusions ECG-gated acquisition of 3D IVUS image sets is feasible and permits the application of automated contour detection to provide reproducible measurements of the lumen and atherosclerotic plaque CSA and volume in a relatively short analysis time