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The reflected ultrasound is received by the probe, transformed into an electric impulse as voltage, and sent to the engine for signal processing and conversion to an image on the screen. The depth reached by the ultrasound beam is dependent on the frequency of the probe used. The higher the frequency, the lesser the depth reached. [9]
Schematic view of a flow sensor. An ultrasonic flow meter is a type of flow meter that measures the velocity of a fluid with ultrasound to calculate volume flow. Using ultrasonic transducers, the flow meter can measure the average velocity along the path of an emitted beam of ultrasound, by averaging the difference in measured transit time between the pulses of ultrasound propagating into and ...
Functional ultrasound imaging (fUS) is a medical ultrasound imaging technique for detecting or measuring changes in neural activities or metabolism, such as brain activity loci, typically through measuring hemodynamic (blood flow) changes. It is an extension of Doppler ultrasonography.
The Doppler fetal monitor is commonly referred to simply as a Doppler or fetal Doppler. It may be classified as a form of Doppler ultrasonography (although usually not technically -graphy but rather sound-generating). Doppler fetal monitors provide information about the fetus similar to that provided by a fetal stethoscope. One advantage of the ...
All modern ultrasound scanners use pulsed Doppler to measure velocity. Pulsed wave instruments transmit and receive series of pulses. The frequency shift of each pulse is ignored, however the relative phase changes of the pulses are used to obtain the frequency shift (since frequency is the rate of change of phase).
A Doppler ultrasound blood flow detector, commonly called Doppler wand or Doppler probe, and a sphygmomanometer (blood pressure cuff) are usually needed. The blood pressure cuff is inflated proximal to the artery in question. Measured by the Doppler wand, the inflation continues until the pulse in the artery ceases.
From these, it is easy to calculate the area (in cm 2) of the aortic valve by simply dividing the LV stroke volume (in cm 3) by the AV VTI (in cm) measured on the spectral Doppler display using continuous-wave Doppler. [citation needed] Stroke volume = 0.785(π/4) x Diameter 2 x VTI of LVOT Cross sectional area of LVOT = 0.785(π/4) x LVOT ...
The ultrasound probe emits a high-frequency sound wave (usually a multiple of 2 MHz) that bounces off various substances in the body. These echoes are detected by a sensor in the probe. In the case of blood in an artery, the echoes have different frequencies depending on the direction and speed of the blood because of the Doppler effect. [2]