Physical principles of doppler and color doppler ultrasound

Abstract

Doppler ultrasound is based on application of the Doppler effect, also called the Doppler shift. In medicine the ultrasound wave is reflected off the moving objects which are erythrocytes in blood vessels. The following types of applications of the Doppler shift in diagnostic imaging are distinguished: Spectral Doppler, including Continuous wave Doppler and Pulsed wave Doppler, Color Doppler, also called Color flow Doppler and Power Doppler. Applications of Doppler ultrasound within the head and neck region include the following: examination of blood flow in big blood vessels, assessment of vascularization of different lesions, assessment of vascular pattern in lymph nodes in differentiating normal, inflamed, neoplastic, and metastatic ones. Contrast media are composed of microbubbles or nanobubbles of gas stabilized with a phospholipid membrane. Applications of ultrasound contrast media in the head and neck include: dynamic examinations of vascularity, salivary gland tumors, improved visualization of obstructive diseases of salivary glands, secretory dysfunctions of salivary glands, and differentiation between benign and malignant thyroid nodules.