UltraSound - Technology Information PortalThursday, 21 February 2019


 'History of Ultrasound Contrast Agents' 
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History of Ultrasound Contrast AgentsInfoSheet: - Contrast Agents - 
Historical Development, 
etc.MRI Resource Directory:<br> - History of UltraSound -
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:
point first generation USCA = non-transpulmonary vascular;;
point second generation USCA = transpulmonary vascular, with short half-life (less than 5 min);
point 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.
Radiology-tip.comSafety of Contrast Agents
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 Further Reading:
The First Long-Lasting Use of Echocardiography: A Result of a False AdvertisementOpen this link in a new window
2008   by imaging.onlinejacc.org    
  News & More:
The clinical applications of contrast echocardiography(.pdf)Open this link in a new window
2000   by cme.medscape.com     
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Medical ImagingMRI Resource Directory:<br> - History of UltraSound -
The definition of imaging is the visual representation of an object. Medical imaging began after the discovery of x-rays by Konrad Roentgen 1896. The first fifty years of radiological imaging, pictures have been created by focusing x-rays on the examined body part and direct depiction onto a single piece of film inside a special cassette. The next development involved the use of fluorescent screens and special glasses to see x-ray images in real time.
A major development was the application of contrast agents for a better image contrast and organ visualization. In the 1950s, first nuclear medicine studies showed the up-take of very low-level radioactive chemicals in organs, using special gamma cameras. This medical imaging technology allows information of biologic processes in vivo. Today, PET and SPECT play an important role in both clinical research and diagnosis of biochemical and physiologic processes. In 1955, the first x-ray image intensifier allowed the pick up and display of x-ray movies.
In the 1960s, the principals of sonar were applied to diagnostic imaging. Ultrasonic waves generated by a quartz crystal are reflected at the interfaces between different tissues, received by the ultrasound machine, and turned into pictures with the use of computers and reconstruction software. Ultrasound has been imported into practically every area of medicine as an important diagnostic tool, and there are great opportunities for its further development. Looking into the future, the grand challenges include targeted contrast imaging, real-time 3D or 4D ultrasound, and molecular imaging. The earliest use of ultrasound contrast agents (USCA) was in 1968.
Digital imaging techniques were implemented in the 1970s into conventional fluoroscopic image intensifier and by Godfrey Hounsfield with the first computed tomography. Digital images are electronic snapshots sampled and mapped as a grid of dots or pixels. The introduction of x-ray CT revolutionised medical imaging with cross sectional images of the human body and high contrast between different types of soft tissue. These developments were made possible by analog to digital converters and computers. The multislice spiral CT technology has expands the clinical applications dramatically.
The first MRI devices were tested on clinical patients in 1980. With technological improvements including higher field strength, more open MRI magnets, faster gradient systems, and novel data-acquisition techniques, MRI is a real-time interactive imaging modality that provides both detailed structural and functional information of the body.
Today, imaging in medicine has advanced to a stage that was inconceivable 100 years ago, with growing medical imaging modalities:
X-ray projection imaging
Computed tomography (CT / CAT)
Ultrasound (US)
Magnetic resonance imaging (MRI)
Single photon emission computed tomography (SPECT)
Positron emission tomography (PET)
Magnetic source imaging (MSI)
All this type of scans are an integral part of modern healthcare. Because of the rapid development of digital imaging modalities, the increasing need for an efficient management leads to the widening of radiology information systems (RIS) and archival of images in digital form in Picture Archiving and Communication System (PACS). In telemedicine, medical images of MRI scans, x-ray examinations, CT scans and ultrasound pictures are transmitted in real time.
See also History of Ultrasound Contrast Agents, and History of Ultrasound.

• View the news results for 'Medical Imaging' (30).

 Further Reading:
  News & More:
Transmission Line Matrix (TLM) modelling of medical ultrasound(.pdf)Open this link in a new window
   by www.era.lib.ed.ac.uk    
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Stress EchocardiogramMRI Resource Directory:<br> - Cardiac -
Stress echocardiograms are used for detection of coronary artery disease, or to determine the cardiac performance. Stress echocardiograms are less performed to evaluate pulmonary artery pressures, pulmonary hypertension or the significance of valvular heart disease.
Stress increases the degree to which the heart contracts. After a myocardial infarction there will be a region of the heart muscle that contracts abnormal at rest. This area may worsen with stress. A coronary artery blockage most often do not impairs the function of the heart at rest. With stress, a region of the heart does not receive enough blood to work effectively and wall motion abnormalities occur. The echocardiographer compares rest and exercise and can determine the presence and severity of a coronary artery blockage.

Stress echocardiograms involve:
list_point bicycle stress echocardiography;
list_point dobutamine stress echocardiography;
list_point transthoracic echocardiography.
A bicycle stress echocardiogram involves transthoracic echocardiography performed at the rest baseline and after or during different stages of physical exercise.
A dobutamine stress echocardiography uses the drug dobutamine instead physical exercise.
Transthoracic echocardiograms are routinely performed during stress and rest.
Cardiovascular stress represents a minimal risk to the patient.
See also Transesophageal Echocardiography, Echocardiography, M-Mode, Curved Transducer, Doppler Ultrasound, History of Ultrasound and History of Ultrasound Contrast Agents.

 Further Reading:
Contrast Stress EchocardiographyOpen this link in a new window
   by www.circ.ahajournals.org    
  News & More:
Non-invasive diagnosis of coronary artery disease by quantitative stress echocardiography: optimal diagnostic models using off-line tissue Doppler in the MYDISE study(.pdf)Open this link in a new window
   by eurheartj.oxfordjournals.org    
US Resources  
Breast - Modes - Universities - Non-English - Resources pool - Resources
Third Generation USCAInfoSheet: - Contrast Agents - 
Historical Development, 
etc.MRI Resource Directory:<br> - Contrast Agents -
The third generation ultrasound contrast agents (UCA/USCA) are more echogenic and stable, and are able to enhance the echogenicity of parenchyma on B-mode images. These microbubbles may thus show perfusion, even in such a difficult region as the myocardium.
See also History of Ultrasound Contrast Agents.

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