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Amersham Health, now GE Healthcare was the imaging diagnostics and therapy business of Amersham plc. The imaging business produced contrast agents that are injected into the body to improve pictures obtained through medical imaging scans.

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GE Medical Systems and Amersham announced in April 2004 the completion of a share exchange acquisition of Amersham Health by GE. The result of this acquisition is the new GE Healthcare, based in the UK, totally owned by General Electric (GE).

The British company was a producer of contrast-imaging agents used to enhance image quality in X-ray, magnetic resonance imaging, and ultrasound procedures. It was also a leading producer of radiopharmaceuticals used in nuclear medicine imaging. Amersham Health was the firm's imaging, diagnostics, and therapeutics segment. Amersham was involved in biotechnology research through its Amersham Biosciences unit, which makes scanners, sequencers, microarrays, industrial separations, and other research supplies.

From Bracco Research S. A., Geneva, Switzerland
BG1135 is a polymer-shelled new ultrasound contrast agent under development. The air-filled microsphere has a rigid, 100 nm thick polymeric shell and a mean diameter of 2.9 μm with 99% less than 8 μm.
The destruction mechanism of BG1135 is unique among microbubbles. The microbubbles of BG1135 appear to acquire a small shell defect, allowing the filling gas to stream out and creating a new gas bubble, but leaving the old shell intact. No significant differences between the diameters of the shells can be measured before and after insonation even though the agent is fragmented.

The wider the ultrasound beam, the more severe the problem with volume averaging and the beam-width artifact, to avoid this, the ultrasound beam can be shaped with lenses.
Different possibilities to focus the beam:

Conventional multi-element transducers are electronically focused in order to minimize beam width. This transducer type can be focused electronically only along the long axis of the probe where there are multiple elements, along the short axis (elevation axis) are conventional transducers only one element wide. Electronic focusing in any axis requires multiple transducer elements arrayed along that axis. Short axis focusing of conventional multi-element transducers requires an acoustic lens which has a fixed focal length.
For operation at frequencies at or even above 10 MHz, quantization noise reduces contrast resolution. Digital beamforming gives better control over time delay quantization errors. In digital beamformers the delay accuracy is improved, thus allowing higher frequency operation. In analog beamformers, delay accuracy is in the order of 20 ns.
Phased beamformers are suitable to handle linear phased arrays and are used for sector formats such as required in cardiography to improve image quality. Beamforming in ultrasound instruments for medical imaging uses analog delay lines. The signal from each individual element is delayed in order to steer the beam in the desired direction and focuses the beam.
The receive beamformer tracks the depth and focuses the receive beam as the depth increases for each transmitted pulse. The receive aperture increase with depth. The lateral resolution is constant with depth, and decreases the sensitivity to aberrations in the imaged tissue. A requirement for dynamic control of the used elements is given. Since often a weighting function (apodization) is used for side lobe reduction, the element weights also have to be dynamically updated with depth.

See also Huygens Principle.

Breast ultrasound (sonography or ultrasonography) it is an important tool in the characterization of breast lesions, detected with mammography or clinical breast examination. However, a breast sonogram is not approved by the U.S. Food and Drug Administration (FDA) as a screening tool for breast cancer and is used additional to a mammogram.
Ultrasound is useful in guiding needles for fine needle aspiration and core biopsies. Breast ultrasound has optimal contrast resolution, but it lacks the spatial resolution of conventional mammography and cannot provide as much detail as a mammogram image. In addition, ultrasound is unable to show tiny calcium deposits (microcalcifications) that are often early indications of breast cancer.

See also Biopsy, Interventional Ultrasound, Ultrasound Safety, Side Effect and Ultrasound Regulations.