In quantitative ultrasonic flow measurements, the beam-to-flow angle (i.e., Doppler angle) is an important parameter. An autoregressive (AR) spectral analysis technique in combination with the Doppler spectrum broadening effect was previously proposed to estimate the Doppler angle. Since only a limited number of flow samples are used, real-time two-dimensional Doppler angle estimation is possib...

Doppler ultrasound is the initial non-invasive study for evaluation of carotid vasculature, it will help us to establish presence tortuous paths, presentation variable, flow velocities, and if there a hemodynamic repercussion. In this pictorial review article, different presentations tortuosities be discussed, as well correct color spectral Doppler.

BACKGROUND AND PURPOSE Knock-type Doppler signals (KTDS) are detectable by transcranial Doppler, and it has been hypothesized that they are related to an occlusion of a small perforating artery and microvascular ischemia. However, the nature of KTDS has not been prospectively defined. We aimed at describing the spectral and power motion Doppler characteristics of KTDS and ultrasound exposure co...

Purpose: The aim of the study is to characterize the ultrasound and Doppler ultrasound artifact patterns of foreign bodies and to define the role of elastography in their detection. Material and method: Two in-vitro environments including a lamb leg and a lamb stomach coated with ultrasound gel, were prepared. Twenty-seven foreign bodies grouped as metallic, organic and inorganic were evaluated...

Femoral arteriovenous fistula is a rare complication of percutaneous transfemoral catheterization. We report the duplex Doppler findings of three such cases. Continuous positive diastolic arterial flow, as well as an abnormal venous flow pattern, was observed in all cases. When present, these Doppler spectral changes support the diagnosis of arteriovenous fistula.

An interferometric method for parallel optical spectroscopy in the kilohertz range is reported, as well as its experimental validation in the context of high-speed laser Doppler imaging in vivo. The interferometric approach enables imaging in the low light conditions of a 2 kHz frame rate recording with a complementary metal-oxide semiconductor camera. Observation of mice craniums with near-inf...

Absract In this work, transcranial Doppler signals recorded from the temporal region of brain on 35 patients were transferred to a personal computer (PC) via 16 bit sound card. FFT, AR and WT methods were applied to transcranial Doppler for obtaining sonograms. Spectral analysis were obtained in order to compare with three methods in the case of medical diagnosis. The comparison shows that WT m...

A new empirical model for windblown radar ground clutter Doppler spectra is developed based on many clutter spectral measurements obtained with Lincoln Laboratory's L-Band Clutter Experiment (LCE) and Phase One five-frequency (i.e., VHF, UHF, L-, S-, and X-band) instrumentation radars over spectral dynamic ranges reaching 60 to 80 dB below zero-Doppler peaks. The model includes both ac and dc s...

[1] The technique for extracting wave period and wave direction from radar backscattering intensity is well developed, but the determination of spectral density or wave height is hindered by the complex nature of the modulation transfer function. In contrast to backscattering intensity, the Doppler signal of a coherent radar is originated from the radial velocity of the scattering objects. Its ...

We demonstrate the use of tone-burst excitation and time-gated spectral analysis for photoacoustic Doppler mapping of flow in an unperturbed vessel phantom and in a vessel with a spatially varying lumen. The method, which mimics pulsed Doppler ultrasound, enables simultaneous measurement of axial position and flow as well as complete characterization of the Doppler spectrum over a wide range of...