DuplexDopplerultraäänet

DuplexDopplerultraäänet refers to duplex Doppler ultrasonography, a noninvasive imaging modality used to evaluate blood vessels and blood flow. The technique combines B-mode gray-scale ultrasound, which visualizes anatomy, with Doppler ultrasound, which assesses the movement and speed of blood within vessels. The term duplex indicates that both structural imaging and Doppler data are acquired simultaneously.

Principle and technique: A transducer emits ultrasound waves to generate real-time two-dimensional images of vessels. Pulsed-wave Doppler measures blood velocity at a specific location and provides spectral waveforms and quantitative values. Color Doppler overlays flow information on the gray-scale image, showing direction relative to the probe and the relative velocity. In many systems, power Doppler offers greater sensitivity to low-velocity flow but does not provide velocity spectra. Proper technique requires adjusting the insonation angle to minimize measurement error, typically keeping it as close to 60 degrees as practical for velocity assessment. The study is usually performed with the patient in a position that allows easy access to the regions of interest.

Clinical applications: DuplexDopplerultraäänet is widely used in vascular medicine. It evaluates arteries for stenosis or occlusion (such as carotid or peripheral arteries), detects aneurysms, and assists in preoperative planning. It also assesses venous disease, including deep vein thrombosis, chronic venous insufficiency, and surveillance of vascular access in hemodialysis.

Advantages and limitations: It is noninvasive, radiation-free, and provides both anatomy and hemodynamics in real time. Limitations include operator dependency, patient body habitus, edema, and calcifications that can hinder visualization or Doppler signals. The accuracy depends on proper technique, angle selection, and correlation with clinical context.