Search results for "Doppler effect"
showing 10 items of 148 documents
Color doppler ultrasonography of soft-tissue masses
1998
Purpose: To evaluate the capability of color Doppler ultrasonography to differentiate between benign and malignant soft-tissue tumors. Material and Methods: We reviewed the ultrasonographic (US) and color Doppler (CD) findings in 46 consecutive patients with a palpable periskeletal mass. The presence of 3 or more vascular hila and of tortuous and irregular internal vessels within the lesions was considered an indication of malignancy. The CD diagnosis was compared with that obtained at US alone. Results: The sensitivity and specificity of CD were respectively 85% and 92%; these values were higher than those obtained at US alone, respectively 75% and 50%. Arteriovenous malformations present…
Evaluation of diastolic function by the Tissue doppler in children affected by non- compaction
2007
The Tissue doppler analysis is a new echocardiographic approach to evaluate the diastolic function. In this report we performed a Tissue doppler analysis in a series of 15 children affected by non-compaction. The bidimensional echo-cardiogram showed a systolic function which was reduced only in 8 patients. Alterations of the diastolic function were founded in 7 patients: in 2 cases, a reduction of the E tissue wave was present in all segments. In 3 patients the diastolic dysfunction was limited to apical and lateral segments. In the last 2 children a reduction of the E wave interested only the apical segments. There was a strong correlation between systolic and diastolic dysfunction: in fac…
Left ventricular function analyzed by Doppler and echocardiographic methods in short-term hypothyroidism
1995
Abstract In conclusion, a significant reversible decrease in contractility and an impaired diastolic relaxation was demonstrated in patients with short-term hypothyroidism. This must be considered in patients with preexisting heart disease.
Vascular mapping of the face: B-mode and doppler ultrasonography study.
2015
Background To analyze the face vascularization pattern using B-mode and Doppler ultrasonography, and also propose an arterial vessel mapping. Material and Methods The investigation was performed on 20 ultrasonography exams of facial vessels through linear and endocavitary transducers. We analyzed and determined the average values for diameters, peak systolic velocity and resistive index of the following arteries: external carotid, lingual, deep lingual, sublingual, facial, submental, inferior labial, superior labial, angular, maxillary inferior alveolar, mental, buccal, greater palatine, infraorbital, superficial temporal, transverse facial and frontal. Results Data was obtained allowing th…
CT-guided stereotactic biopsy aided by Doppler ultrasonic vascular monitoring
1992
The use of a 20 MHz pulsed Doppler technique during stereotactic brain tumour biopsies is described. By means of a miniaturized ultrasonic probe the tissue planned for biopsy was investigated for vessel signals. Out of 41 patients, with this technique a flow-pulse curve in front of the biopsy cannula was registered in 14 cases. In 9 cases one pulse curve was determined and in 5 cases two or more flow curves were found, indicating the presence of arterial vessels. The depth of the vessels signal could be localized and this area avoided for biopsy sampling. In a series of 41 stereotactic biopsies carried out in this way there was no intra-operative haemorrhage or postoperative haematoma.
Comparison of the sympathetic skin response and continuous wave Doppler sonography of the radial artery.
1999
The value of neurophysiological tests of the autonomic nerve system is limited. One of the clinically most commonly applied test is the skin sudomotor response, frequently referred to as 'sympathetic skin response' (SSR). However, the SSR is a more qualitative than quantitative evaluation technique. Continuous wave (cw) Doppler sonography of the radial artery may be an alternative quantitative approach. We studied 41 age matched volunteers (23 female, 18 male; 16-82 years (mean age 53 years)). The stimulus was a loud and unexpected acoustic signal, alternatively a cough. SSR evaluation included the latency of onset, the duration and the amplitude of the response. Doppler evaluation also inc…
Localization of segmental arteries in renal surgery by Doppler sonography.
1982
Abstract To avoid damage to major arteries of the renal parenchyma during nephrotomy, intraoperative Doppler sonography was used experimentally and clinically as an artery finder. In experiments with 7 beagles segmental arteries were detected easily and reliably by sonography, and the arterial course thus indicated correlated perfectly with arteriograms and casts. In a clinical trial the Doppler artery finder was used in 7 patients with staghorn calculi that were removed via the renal pelvis and additional multiple selective nephrotomies. With as many as 7 selective nephrotomies in a single kidney there was no damage to the major arteries in any of these patients. Selective, avascular nephr…
Blood flow velocity waveforms of the fetal middle cerebral artery in a normal population: reference values from 18 weeks to 42 weeks of gestation
2002
The aim of this prospective cross-sectional study was to establish new Doppler reference curves for peak blood flow velocities (Vmax, Vmean, Vmin) and impedance indices (PI, RI) of the middle cerebral artery at 18-42 weeks of gestation by an automatic wave form analysis integrated into the ultrasound device. In 962 low-risk pregnancies, blood flow velocities were derived from the middle cerebral artery with pulsed color Doppler ultrasonography. Reference curves were constructed for the individual parameters based on a growth function from a four-parameter class of monotonic continuous functions according to the smallest square principle for maximum blood flow velocities, as well as on a pol…
Doppler and B-mode ultrasound for avascular nephrotomy.
1983
AbstractDoppler sonography for intraoperative localization of the intrarenal arteries combined with B-scan sonography for intraoperative visualization of stones allows complete stone removal via small radial nephrotomies for which clamping of the renal artery is no longer necessary. Since September 1980 we used this technique on 35 patients with staghorn or recurrent calculi. The main advantages of this technique are exact and quick stone localization, minimal loss of renal function owing to preservation of the intrarenal vascular system, and no need for renal ischemia and cooling.
LTE-based passive radars and applications: a review
2021
This paper provides an overview of the most recent passive radars based on long-term evolution (LTE). To begin, this paper investigates the various characteristics and requirements of 4 G LTE signals for radar, taking performance aspects such as range, velocity, range resolution, and velocity resolution into account. An ambiguity function analysis is performed on a measured LTE signal using the synchronization and reference signal components to evaluate key performance parameters such as Doppler and range characteristics. We also discuss how LTE passive radar can be used in a variety of applications. The detailed analysis of the LTE downlink signal, its structural overview, and the effect o…