The dead or ring down zone is the distance from the front face of the transducer to the first echo that is identifiable. The signals from this region are unsuitable. The dead zone is the result of transducer ringing and reverberations from the interface between the transducer and the scanned object. Impedance matching between the transducer and the receiver is important to avoid electrical ringing.
With an increase of the frequency, the pulse length and the depth of the dead zone decrease, if all other parameters remain constant. The acoustic power also affects the depth of the dead zone.

From Lantheus Medical Imaging.
Activated DEFINITY® Injectable Suspension is indicated for use in patients with suboptimal echocardiograms to opacify the left ventricular chamber and to improve the delineation of the left ventricular endocardial border. The perflutren lipid microspheres exhibit lower acoustic impedance than blood and enhance the intrinsic backscatter of blood.
Echocardiography with Definity produced more detailed images of the heart in difficult-to-image patients versus echocardiography alone, and images obtained with the contrast agent provided a more accurate assessment of segmental wall motion compared with unenhanced images.

See also Coherent Contrast Imaging.

In August 2001 DuPont Pharmaceuticals Company received FDA approval.

Duplication artifacts can be created through diffraction and refraction on interfaces, also if the acoustical impedances of tissue is too much different and the ultrasound is reflected multiple on tissue layers, where the detected echo does not come from the shortest sound path.

See also Mirror Artifact.

From Hitachi Medical Corporation (HMC), sales, marketing and service in the US by Hitachi Medical Systems America Inc.;
Powerful, flexible, and fast, the HI VISION™ 8500 - EUB-8500 diagnostic ultrasound scanner combines leading edge technologies with user-oriented operation for exceptional imaging and functionality.
Available exclusively on the 8500, SonoElastography provides a new perspective on the physical properties of tumors and masses by determining and displaying the relative stiffness of tissue.

From Hitachi Medical Corporation (HMC);
The HI VISION™ 6500 - EUB-6500 high resolution digital ultrasound system offers advanced clinical imaging, enhanced operating efficiency, and remarkable clinical flexibility, all in robust and versatile configuration that simply represents a better clinical solution in a variety of real-world, real-work arenas.