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.

The company is a member of the Bracco Group, a highly innovative health care group and world leader in global integrated solutions for the diagnostic imaging field. The Bracco Group is headquartered in Milan, Italy. Its North American operations consist of Bracco Diagnostics and Bracco Research USA, both located in Princeton, New Jersey. Bracco Diagnostics is one of the fastest growing developers and marketers of diagnostic pharmaceuticals in North America, with products for various imaging applications, including Isovue® (iopamidol) X-ray contrast agent, ProHance®, (gadoteridol), MRI contrast agent, and nuclear medicine products.
Gadoteridol has been available in Europe and the USA for several years. Holder of the Marketing Authorization: Bracco International B.V. - Strawinskylaan 3051 - 1077 ZX Amsterdam The Netherlands. (Contact: Kirk Deeter, Phone: +NL-303-838-8708)

The Bracco Group is the world's leading provider of global diagnostic imaging solutions, with net sales of more than 1 billion euro, of which more than 64% from international sales; it has operations in 115 countries and about 3,500 employees, of whom more than 600 work in R&D. Bracco invests around 15% of its turnover in R&D and has a portfolio of 1,500 patents worldwide. The Bracco Group deploys an integrated approach to diagnostic imaging, with an offer that encompasses contrast media, its core business where it is one of the world's top players, biomedical equipment from Esaote, one of the world's primary producers of magnetic resonance and ultrasonographic medical equipment, contrast media delivery systems from Acist Medical Systems, a top US company in advanced contrast media injection systems, and medical application software from EBIT-AET and Singapore's Volume Interactions, the leading developer of advanced medical software. Bracco has formed a high-level international research network, whose three centers in Milan, Geneva and Princeton study and develop products for the latest-generation diagnostic techniques, from X-rays and computerized axial tomography to magnetic resonance and echo contrast.

Ultrasound Contrast Agents:

Cerebrovascular ultrasonography is the best screening tool for the detection of carotid artery stenosis. Transcranial sonography is used in the evaluation of patients with suspected cerebrovascular disease, but a common problem is the attenuation of the ultrasound signal by the skull.
Contrast enhanced ultrasound play a particularly important role in the visualization of the intracranial vessels, and thus improves the accuracy of transcranial Doppler and increases the potential of this technique. The use of microbubbles is helpful for classification of stenosis and for plaque evaluation in patients with poor initial examination. Ultrasound contrast agents avoid misdiagnosing a subtotal stenosis, which is a very important clinical issue.

See also Adventitia, Intima, Periorbital Doppler, and Acoustic Window.

(CCI) A major limitation of the use of ultrasound contrast agents is the problem that signals from the microbubbles are mixed with those from tissue, so that the distribution of the microbubbles is not optimally displayed either in Doppler or gray scale.
Coherent contrast imaging is a high frame rate implementation of inverting the phase of alternate sound pulses and summing the resulting echoes. The symmetrical signals from linear reflectors are cancelled leaving those from non-linear scatterers, with the advantage that the cancellation is performed without the need to transmit two pulses per image line so that bubble destruction is minimized. Coherent contrast imaging yields best results in the vascular phase of phospholipid microbubbles (such as Definity and SonoVue).

See also Coherence.

(CEUS) Contrast agents increase the reflection of ultrasonic energy, improve the signal to noise ratio and caused by that the detection of abnormal microvascular and macrovascular disorders. Contrast enhanced ultrasound is used in abdominal ultrasound (liver sonography) as well as in cerebrovascular examinations e.g., for an accurate grading of carotid stenosis. The used contrast agents are safe and well tolerated.

The quality of the enhancement depends on:
The additional use of ultrasound contrast agents (USCAs) may overcome typical limitations like poor contrast of B-mode imaging or limited sensitivity of Doppler techniques. The development of new ultrasound applications (e.g., blood flow imaging, perfusion quantification) depends also from the development of pulse sequences for bubble specific imaging. In addition, contrast enhanced ultrasound improves the monitoring of ultrasound guided interventions like RF thermal ablation.

See also Contrast Enhanced Doppler Imaging, Contrast Harmonic Imaging, Contrast Imaging Techniques and Contrast Pulse Sequencing.