UltraschallDoppler

UltraschallDoppler, commonly referred to as Doppler ultrasound, is a non-invasive medical imaging technique that uses the Doppler effect to assess motion, most often blood flow in vessels and the heart. The method combines conventional ultrasound imaging with Doppler measurements to determine the speed and direction of moving structures, typically red blood cells.

Principle: An ultrasound transducer emits high-frequency sound waves that travel through tissue and reflect off moving blood cells. The frequency of the reflected waves shifts in proportion to the velocity of motion relative to the transducer. By analyzing these frequency shifts, the system can quantify flow velocity and indicate flow direction (toward or away from the transducer).

Modes and variants: Doppler ultrasound includes continuous-wave Doppler for high-velocity measurements and pulsed-wave Doppler for location-specific sampling, as well as color Doppler, which encodes flow direction and speed as colors over a B-mode image. Doppler data can be displayed as spectral traces or velocity maps.

Applications: In cardiology, Doppler ultrasound is a core component of echocardiography, assessing valve function, chamber pressures, and cardiac output. In vascular medicine, it evaluates arterial and venous beds for stenosis, occlusions, clots, and graft patency. It is also used in obstetrics for fetal well-being and in various abdominal and pelvic examinations.

Safety and limitations: Doppler ultrasound is non-ionizing and generally regarded as safe. Limitations include operator dependence, angle of insonation, and potential aliasing with high-velocity flow. Body habitus, calcifications, and overlying gas can reduce image quality or Doppler accuracy. No special preparation is usually required for a standard study.