Reference Guide for Pulsed-Doppler Signals from the Right Side of the Heart

1988 ◽  
Vol 5 (4) ◽  
pp. 259-267
Author(s):  
INA DAM ◽  
THEO BOO ◽  
ELLY LAKWIJK ◽  
JEROEN HOPMAN ◽  
ANTON OORT ◽  
...  
Keyword(s):  
Pulsed Doppler ◽  
Reference Guide ◽  
Doppler Signals ◽  
The Right

Reference values for pulsed Doppler signals from the blood flow velocity on both sides of the pulmonary valve

1988 ◽  
Vol 9 (4) ◽  
pp. 388-394 ◽  
Author(s):  
A. VAN OORT ◽  
S. DE KNECHT ◽  
I. VAN DAM ◽  
A. HERINGA ◽  
T. DE BOO ◽  
...  
Keyword(s):  
Blood Flow ◽  
Flow Velocity ◽  
Reference Values ◽  
Blood Flow Velocity ◽  
Pulmonary Valve ◽  
Pulsed Doppler ◽  
Doppler Signals

Bias and Variance in the Estimate of the Doppler Frequency Induced by a Wall Motion Filter

1989 ◽  
Vol 11 (3) ◽  
pp. 215-225 ◽  
Author(s):  
J.C. Willemetz ◽  
A. Nowicki ◽  
J.J. Meister ◽  
F. De Palma ◽  
G. Pante
Keyword(s):  
Wall Motion ◽  
Low Frequency ◽  
Doppler Frequency ◽  
Correlated Noise ◽  
Pulsed Doppler ◽  
Flow Mapping ◽  
Frequency Shifts ◽  
Doppler Signals ◽  
Frequency Aliasing ◽  
Correlation Techniques

In pulsed Doppler flowmeters, processing of the Doppler signals is often done digitally. The first step in the analysis of the echoes is the filtering which is needed to remove stationary components and low frequency shifts induced by wall motion. This preliminary step is of utmost importance. The influence of uncorrelated noise on the measurement of Doppler signals at the input of this filter is analysed. The frequencies of the Doppler signals are extracted by an algorithm based on correlation techniques. We observed that the filter induces a correlated noise term, which results in an overestimation of the frequency. An effect similar to frequency aliasing may appear. The level of the bias is dependent on filter characteristics and noise level. Our study was carried out on simulated Doppler signals using first and second order filters. An especially desirable solution in flow mapping is proposed in order to decrease this error.

Analysis of the projected image of tourism destinations on photographs: A literature review to prepare for the future

2017 ◽  
Vol 25 (1) ◽  
pp. 3-24 ◽  
Author(s):  
Patricia Picazo ◽  
Sergio Moreno-Gil
Keyword(s):  
Literature Review ◽  
Destination Image ◽  
Integral Approach ◽  
Future Research ◽  
Limited Attention ◽  
Projected Image ◽  
Reference Guide ◽  
Comprehensive Literature Review ◽  
Tourism Destinations ◽  
The Right

Making the right impression is paramount to succeed in today’s very competitive market, where photographs have acquired a prominent role in doing so. The evaluation and analysis of destination image have been tackled mainly from the perspective of the tourists’ perceptions. However, the projected image of destinations has received limited attention in the literature and the topic has not yet been successfully operationalized. Moreover, existing literature on the projected image on photographs (PIP) is scattered and lacking of an integral approach. Thus, the aim of this article is to fill this gap by carrying a comprehensive literature review on the destination’s PIP, covering information sources analyzed, destinations included, number of pictures, time framework, methodology, and specially categorization (people, activities represented, and tourism context) and specific attributes used. As a result, this article provides researchers with a reference guide to understand the current situation of the research on this topic, context, methods, and focus of previous studies. Finally, it identifies trends and reflections on future research.

Use of contrast in ultrasound

2011 ◽  
Author(s):  
Tomas Jansson ◽  
Anders Nilsson
Keyword(s):  
New York ◽  
Left Atrium ◽  
In Vitro Study ◽  
Rapid Injection ◽  
Doppler Signals ◽  
The World ◽  
Vitro Model ◽  
The Right ◽  
The University

In 1968, Drs Pravin M. Shah and Raymond Gramiak at the University of Rochester, New York, were conducting a study with the ultimate goal to investigate whether heart stroke volume could be estimated from the extent and duration of cusp separation of the aortic valve, as measured with M-mode ultrasound. Simultaneously, as the reference, they also measured cardiac output with the indicator dilution technique. Here, a bolus of a dye (indocyanine green) is injected and blood is sampled downstream to determine the rate at which the indicator has been transported from the injection site. In Dr Shah’s own account of the experiments, he explains that the routine at his university then was to place a catheter in the left atrium with the trans-septal technique, i.e. inserting the catheter in a vein and penetrating into the left atrium via the right atrium. During the injections of the dye, somewhat to their surprise, they observed a striking echo enhancement across the aorta. The enhancement also appeared when saline and dextrose in water was flushed through the catheter. Dr Gramiak reminded himself of a comment from Dr Claude Joyner, that a temporary echo-enhancement could be observed during saline injections, and they speculated that miniature bubbles produced by gaseous cavitation upon rapid injection of the fluid gave rise to the enhancement, and raised the idea that this could be used as a contrast agent. An in vitro study by Frederick Kremkau provided strong evidence that gas bubbles were actually responsible for the echo enhancement. It is interesting to note how discoveries are made independently around the world, when the time is ripe. At the same time in Lund, Drs Inge Edler and Kjell Lindström performed studies to measure blood flow in the heart. At this point no ultrasound Doppler signals had been recorded from the inside of the heart, and they used a calf heart in an in vitro model to verify that signals could be obtained when water and blood was led through the model.

scholarly journals Biometric, B-mode and color Doppler ultrasound assessment of eyes in healthy dogs

2018 ◽  
Vol 38 (3) ◽  
pp. 565-571
Author(s):  
Elzivânia G. Silva ◽  
Gerson T. Pessoa ◽  
Laecio S. Moura ◽  
Porfírio C. Guerra ◽  
Renan P.S. Rodrigues ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Doppler Ultrasound ◽  
Statistical Difference ◽  
Ophthalmic Artery ◽  
Anterior Chamber Depth ◽  
Pulsed Doppler ◽  
Resistivity Index ◽  
Hemodynamic Assessment ◽  
The Mean ◽  
The Right

ABSTRACT: B-scan ultrasonography is an important diagnostic tool that allows characterization of internal organ anatomy and, when complemented by Doppler ultrasound, allows vascular hemodynamic assessment, increasing the diagnostic accuracy. Thus, the aim of the present study was the B-scan ultrasound characterization and measurement of the eyeball segments and assessment of the external ophthalmic artery by color and pulsed Doppler. Sixty eyeballs were assessed from 30 dogs of different breeds using an 8.5MHz microconvex transductor. First, biometry was performed by B-scan of the following segments: axial length (M1), anterior chamber depth (M2), lens thickness (M3), lens length (M4), vitreous chamber depth (M5), optical disc length (M6) and optic nerve diameter (M7). Colored Doppler identified the external ophthalmic article and pulsed Doppler assessed its flow, and the following were measured: systolic peak velocity (VPS), final diastolic velocity (VDF), resistivity index (IR) and pulse index (IP). No statistical difference was observed for the biometric values of the eye segments between the right and left eyes (p>0.05). The vitreous chamber depth (M5) was shown to be the biometric variable with greatest bilateral symmetry, varying from 0.79 to 0.87cm and 0.78 to 0.86cm for the right and left eye, respectively. The ophthalmic artery was visualized over the optic nerve towards the eyeball, with flow stained red. There was no significant statistical difference between the Doppler velocimetric values for the ophthalmic artery between the right and left eye of the animals assessed (p>0.05). The mean resistivity index (RI) showed average values equal to 0.63±0.03, bilaterally. The mean base velocity was 17.50cm/s and 18.18cm/s at the systolic peak and 6.21cm/s and 6.68cm/s at the end of the diastole, for the right and left eyes respectively. The anatomic, biometric and hemodynamic characterization using the ultrasound B-scan and the Doppler modalities permitted the ultrasonographic and Doppler velocimetric assessment of the eyeball components in dogs of different breeds, and it can be used in ophthalmic clinical routine to identify eye pathologies.

Ex-vivo renal surgery and auto-transplantation for benign and malignant renal pathologies: our early evolving experience of three cases

2017 ◽  
Vol 11 (1) ◽  
pp. 27-32
Author(s):  
Muhammad Z Aslam ◽  
Tim Brown ◽  
Ali A Thwaini
Keyword(s):  
Partial Nephrectomy ◽  
Ex Vivo ◽  
Intraoperative Complications ◽  
Disease Recurrence ◽  
Laparoscopic Nephrectomy ◽  
Renal Surgery ◽  
Renal Functions ◽  
Doppler Signals ◽  
The Right

Objectives: We describe our experience of ex-vivo renal surgery and autotransplantation for complex renal pathologies. These cases were carried out in the urology and transplant departments between July 2015 and January 2016. Materials and methods: Case 1 was a 63-year-old man presenting with spontaneous bleed from a renal mass in a solitary functional right kidney. Case 2 was a 50-year-old man with bilateral renal tumours involving renal veins. Case 3 was a 50-year-old man with two previous failed right-sided pyeloplasties. Results: No intraoperative complications were encountered. Case 1 underwent laparoscopic nephrectomy, ex-vivo partial nephrectomy followed by autotransplantation. There was no disease recurrence after 6 months’ follow-up, with stable renal functions. Case 2 had bilateral open radical nephrectomies performed. On the right autotransplantation was performed after ex-vivo partial nephrectomy. On the left, a further procedure was abandoned after radical nephrectomy due to extensive disease involvement. Postoperatively, the patient became anuric with poor Doppler signals. Exploration suggested complete renal vein obstruction with infarction of the autotransplanted right kidney requiring nephrectomy. Disease recurrence at the native renal bed was found at 6 months’ follow-up. Case 3 had laparoscopic nephrectomy, ex-vivo pyeloplasty and autotransplantation was performed. At 12 months’ follow-up, the patient was asymptomatic with stable renal functions. Conclusions: Ex-vivo renal surgery is a viable option for complex renal conditions. However, appropriate patient selection is essential to achieve good outcomes.

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