A curved or curvilinear array transducer is similar to a linear array except that the image created has a sector-type format. A curvilinear array gives a large footprint and near field with a wide sector. Usually, curved transducers are described by the radius of curvature in mm. The transducer elements control the characteristics and direction of the sound beam.
Curvilinear transducers have a wider field of view from the transducer face. Sector scanners are most useful for cardiac ultrasound examinations where the beam is directed between the ribs to image the heart.
Also called convex transducer.

B-scan comined with D-scan (D=Depth) is used to avoid image inhomogeneity. Different transmitter signals for each depth are applied and prefiltered pseudoinversely according to the transfer properties of the covering tissue. Pulse compression techniques with nonlinearly frequency modulated signals are used to gain the required energy for inverse filtering.
D-scan is a modified C-scan used in nondestructive testing with the display of amplitudes. In the 2D graphical presentation, time of flight values are displayed in the top view on a test surface.

See also A-Scan, B-Scan and C-Scan.

Doppler techniques are dependent on the transducers used. The transducer operating in continuous wave mode utilizes one half of the elements and is continuously sending sound energy while the other half is continuously receiving the reflected signals. If the transducer is being used in a pulsed wave mode, the whole transducer is used to send and then receive the returning signals.
Pulsed wave techniques allow the accurate measurement of blood flow at a specific area in the heart and the detection of both velocity and direction. Measurement is performed by timing the reception of the returning signals giving a view of flows at specific depths. The region where flow velocities are measured is called the sample volume. Errors in the accuracy of the information arise if the velocities exceed a certain speed. The highest velocity accurately measured is called the Nyquist limit.

See also Doppler Velocity Signal and Doppler Effect.

EchoGen® is a fluorocarbon-based (dodecafluoropentane) third generation USCA. EchoGen® consists of microbubbles stabilized with surfactants in a phase shift colloid emulsion (perflenapent). EchoGen® requires no preparation, reconstitution, or refrigeration.
Perflenapent emulsion would represent a significant advance in contrast echocardiography caused by effective and long lasting opacification of the left ventricle and enhanced endocardial border delineation.
The persistence of the contrast effect permits interrogation in multiple echocardiographic views, as well as the visualization and localization of myocardial perfusion deficits at rest by producing a negative contrast effect.
October 12, 2000
Sonus Pharmaceuticals, Inc. announced a strategic decision to refocus the Company on the development of its drug delivery and blood substitute products. At the same time, Sonus has withdrawn the NDA (New Drug Application) and discontinued clinical activity for its ultrasound contrast product, EchoGen®.
August 06, 2001
Sonus Pharmaceuticals, Inc. announced that it has entered into an agreement to sell its ultrasound contrast assets for $6.5 million to Amersham plc. As part of the agreement, Sonus has also assigned to Nycomed its interest in the ultrasound contrast patent license agreement entered into with Chugai Pharmaceutical Co. Ltd. and Molecular Biosystems Inc in January 2001.

EchoSeed™ consists of radioactive 125I (iodine-125) seeds/implants indicated for the treatment of prostate cancer with brachytherapy.
The design of this second generation product, used in combination with ultrasound imaging, facilitates optimal placement. EchoSeed™ allows the physician to view both the prostate gland and the seeds during the course of the implant procedure.
Nycomed Amersham. Source: PR Newswire - 06/04/01.