Medical Ultrasound Imaging
Wednesday, 15 May 2024
 Info Sheets  Out- side     | 'Perfusion Imaging' p4 Searchterm 'Perfusion Imaging' found in 20 articles 5 definitions [ • ] - 15 booleans [• ]Result Pages : •
A bolus is a rapid infusion of high dose contrast agent. Dynamic and accumulation phase imaging can be performed after bolus injection. Since the transit time of the bolus is only a short time, images with high frame rate show the wash in and wash out of the contrast material.
The injection rate and the total injected volume modifies the bolus peak profile. Substantial changes in the concentrations during signal acquisition induce artifacts. Furthermore, the hemodynamic parameters (cardiac output, blood pressure) influence the bolus profile. However, the characteristics of ultrasound contrast agents are favorable with a continuous perfusion. See also Negative Bolus. •
Contrast agents improve the sensitivity of vascular Doppler ultrasound, for example in cerebrovascular sonography or examinations of deep abdominal vessels. They also enlarge the role of transcranial Doppler. Microbubbles can be used with various modes e.g., color and power Doppler imaging, as well as pulsed-wave Doppler to increase the signal intensity. However, the ultrasound system must be suitable for contrast enhanced technology. Microbubbles usually stay within the vascular space; nevertheless, the contrast enhancement is limited to 2−6 minutes caused by physiologic clearance and bubble destruction. Depended on the application, contrast agents can be administered with a different injection rate e.g., bolus injection, slow injection, or continuous infusion. Stable, homogeneous, and prolonged enhancement can be obtained with perfusion, lasting until the infusion is stopped. See also Cerebrovascular Ultrasonography, Multiple Frame Trigger. •
Imagent® is an injectable suspension for intravenous administration during a sonogram. This diagnostic contrast agent for enhancement of ultrasound images contains perflexane lipid microspheres. Imagent® US is indicated in the assessment of heart function and perfusion, as well as the detection of tumors and blood flow abnormalities by using gray scale, color Doppler, and harmonic ultrasound imaging techniques. During the course of its development, the brand name for this product has changed from Imagent to Imavist (between August 2000 and March 2002) back to Imagent. The manufacturer's 06/03/02 press release announcing FDA approval refers to the product as 'Imagent (formerly Imavist),' and the approval notice and monograph posted at the FDA site refers to the product as Imagent. Jointly developed by Alliance Pharmaceutical Corp and Bayer Schering Pharma AG (Germany). Source: PR Newswire - 10/10/96, 03/31/98, 10/13/99, 03/13/01, 10/08/01; FDA approvals - 05/31/02; Alliance Pharmaceutical press release - 06/03/02. Currently the production of Imagent® is discontinued.
Drug Information and Specification
RESEARCH NAME
AF0150
DEVELOPER
IMCOR Pharmaceuticals, Inc.
INDICATION
APPLICATION
Intravenous
TYPE
Lipid: DMPC
CHARGE
Neutral
Perfluorohexane/Nitrogen
MICROBUBBLE SIZE
99.8% < 10μm
PRESENTATION
-
STORAGE
Room Temp 15−30 °C
PREPARATION
Reconstitute with 10 ml water
DO NOT RELY ON THE INFORMATION PROVIDED HERE, THEY ARE
NOT A SUBSTITUTE FOR THE ACCOMPANYING PACKAGE INSERT! •
Sonazoid™ is an ultrasound contrast agent (UCA) consisting of stabilized gas microbubbles in an aqueous suspension. Sonazoid™ has overcome the stability problems of first generation USCA and can produce myocardial perfusion images. Myocardial imaging using ultrasound contrast agents provides diagnosis of chronic heart disease and assessment of the coronary arteries and of the coronary blood flow reserve.
Sonazoid™ is taken up by healthy Kupffer cells in the liver and spleen, but break down in high amplitude ultrasound imaging modes such as color Doppler imaging. The bubble rupture produces a transient pressure wave, which results in a characteristic mosaic color pattern from tissues containing the microbubbles (induced acoustic emission). Liver tumors without Kupffer cells will not display the mosaic pattern and can therefore be identified easily.
Drug Information and Specification
RESEARCH NAME
NC100100
DEVELOPER
INDICATION -
DEVELOPMENT STAGE Development in USA and EU suspended
APPLICATION
-
TYPE
Microbubble
Lipid Stabilized (not disclosed)
CHARGE
Negative
Perfluorobutane
MICROBUBBLE SIZE
-
PRESENTATION
-
STORAGE
-
PREPARATION
Reconstitute with 2mL water
DO NOT RELY ON THE INFORMATION PROVIDED HERE, THEY ARE
NOT A SUBSTITUTE FOR THE ACCOMPANYING PACKAGE INSERT! •
The earliest introduction of vascular ultrasound contrast agents (USCA) was by Gramiak and Shah in 1968, when they injected agitated saline into the ascending aorta and cardiac chambers during echocardiographic to opacify the left heart chamber. Strong echoes were produced within the heart, due to the acoustic mismatch between free air microbubbles in the saline and the surrounding blood. The disadvantage of this microbubbles produced by agitation, was that the air quickly leak from the thin bubble shell into the blood, where it dissolved. In addition, the small bubbles that were capable of traversing the capillary bed did not survive long enough for imaging because the air quickly dissipated into the blood. Aside from agitated saline, also hydrogen peroxide, indocyanine green dye, and iodinated contrast has been tested. The commercial development of contrast agents began in the 1980s with greatest effort to the stabilization of small microbubbles. The development generations by now:
•
first generation USCA = non-transpulmonary vascular;;
•
second generation USCA = transpulmonary vascular, with short half-life (less than 5 min);
•
third generation USCA = transpulmonary vascular, with longer half-life (greater than 5 min).
To pass through the lung capillaries and enter into the systemic circulation, microspheres should be less than 10 μm in diameter. Air bubbles in that size range persist in solution for only a short time; too short for systemic vascular use. The first developed agent was Echovist (1982), which enabled the enhancement of the right heart. The second generation of echogenic agents, sonicated 5% human albumin-containing air bubbles (Albunex), were capable of transpulmonary passage but often failed to produce adequate imaging of the left heart. Both Albunex and Levovist utilize air as the gas component of the microbubble. In the 1990s newer developed agents with fluorocarbon gases and albumin, surfactant, lipid, or polymer shells have an increased persistence of the microspheres. This smaller, more stable microbubble agents, and improvements in ultrasound technology, have resulted in a wider range of application including myocardial perfusion. See also First Generation USCA, Second Generation USCA, and Third Generation USCA.  Further Reading: Basics:
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