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In ultrasonic volume imaging, the effect of rotating the transducer about the central axis of the imaging plane is equivalent to rotation of the insonified volume. The authors present schematics to depict the action and sonograms in two cases (a hand immersed in water and a 36-week fetus) to demonstrate this phenomenon. This maneuver can be used to "rotate" the imaged structures, which enhances their three-dimensional representation.

To correct distortion in ultrasonic images caused by refraction at fat-muscle interfaces in the subcutaneous tissues.A forward-propagation technique was developed that used a priori information of the acoustic properties of the layers. The thickness and shape of these tissues were measured, and a correction was applied for the different velocities in the tissues. A synthetic-aperture scanning technique was used to allow correction to be applied with data obtained in a single scan. The technique was tested in three tissue phantoms with overlying aberrating layers (six images) and in eight volunteer subjects (37 images). The superior mesenteric artery and the aorta were used as test sites within the body, because it is relatively easy to obtain double images of these vessels owing to refraction of the scanning beam by the rectus muscles.Distortions such as double-image artifacts and texture disruption were corrected with use of this technique. Six of the six phantom images and 22 of the 37 images in humans were corrected with use of this technique.The forward-propagation technique compensates for refraction at subcutaneous fat-muscle interfaces.

A form of range ambiguity in Doppler ultrasound has been identified. It occurs when a high pulse repetition frequency (prf) is used with a superficial range gate. "Phantom" range gates are then generated at depths beyond the desired range gate, and these may produce artifactual signals. Extremely high prf values should not normally be used, and duplex machines should be programmed to display phantom range gates wherever they fall within the displayed field of view.