In power mode the amplitude (power) of color Doppler signals is displayed, regardless of the velocity. Power does not have negative values and is independent of sampling frequency. An aliasing artifact does not occur in power mode images. Caused by plotting the quantity enhanced by echo contrast agents in a power map, power mode is often used in contrast Doppler ultrasound examinations.
Also known as energy mode.

Power modulation is a non-linear method, based on a multi-pulse technique where the acoustic amplitude (and hence power) of the transmitted pulses is changed. Full and half amplitudes pulses are used to induce changes in the response of the contrast agent. The received echoes from the emitted half amplitude pulse are adjusted with the full amplitude pulse and this pairs of pulses are subtracted. Power modulation is used to separate contrast agent echoes at low mechanical index, allowing real-time perfusion imaging.
Power modulation can be used with a low frequency wide band transducer to increase the depth and transmit the sound beam homogenous allowing ultraharmonic imaging.

Selective detection of the microbubble contrast medium can be enhanced by Doppler processing that removes signals with zero Doppler frequency shifts. This will remove tissue harmonics. By detecting overlong bursts of inverted pulses and using Doppler detection methods, very high sensitivity to microbubbles can be achieved. The bubbles can be detected at sufficiently low incident power levels to avoid destroying them. Pulse inversion Doppler has demonstrated the first real-time images of myocardial perfusion using perfluorocarbon gas agents.

See also Pulse Inversion Imaging, Myocardial Contrast Echocardiography, and Perfluorochemicals.

Quantison, consisting of air-filled microbubbles with stiff and rigid human serum albumin shells, is an investigational ultrasound contrast agent for the assessment of coronary artery disease.
The stiff shell inhibits the bubbles from oscillating and decrease non-linear scattering. Quantison is capable of long lasting cavity contrast and myocardial opacification using intermittent imaging.

Reflux sonography, as an alternative to micturating cystography (MCU), evaluates vesico-ureteral reflux (VUR), a common problem in children. Contrast enhanced pulse-inversion imaging shows best results. During the instillation of an ultrasound contrast agent into the bladder, (as for a conventional MCU) the lower ureters and renal pelves are scanned transabdominally as the bladder is filled to stimulate micturition.
Advantages for reflux sonography are a high sensitivity and the avoidance of X-rays. A disadvantage is the poorer depiction of the posterior urethra. However, for girls and for all follow-up studies, the ultrasound MCU has become standard in many pediatric ultrasound departments.

See also Urologic Ultrasound, Kidney Ultrasound, Ultrasound Safety, Ultrasound Imaging Modes.