How Does Ultrasound Work?
John McCafferty, James M Forsyth in Point of Care Ultrasound Made Easy, 2020
Doppler ultrasonography combines imaging of structure and function. By imaging the heart, vessel or vascular tissue, a sample volume can be positioned within a vascular structure. Powerful signal processing then calculates the phase shift over the sample volume, and both speed and direction of blood movement can be found. In the case of speed or velocity, this can be displayed as a spectral Doppler (Figure 1.8). Direction of flow is usually represented by a colour scale (see Figure 1.8) with blue indicating movement away from the transducer and red indicating movement towards the transducer. This powerful physical principle can be used to quantify blood flow through heart valves and vessels which can be useful in detecting valve blockage (stenosis) or valve leakage (incompetence).
Portal hypertension
Brice Antao, S Irish Michael, Anthony Lander, S Rothenberg MD Steven in Succeeding in Paediatric Surgery Examinations, 2017
Which of the options presented above is the next most appropriate investigation in relation to the following clinical scenarios? Each option may be used once, more than once, or not at all. A 7-month-old infant with cholestasis and splenomegaly. Patient had an initial abdominal Doppler ultrasonography.A 5-year-old girl with haematemesis and thrombocytopenia. Patient had an initial abdominal Doppler ultrasonography.A 12-year-old girl with hepatomegaly, splenomegaly and ascites. Patient had an initial abdominal Doppler ultrasonography.
Nephrology
Shibley Rahman, Avinash Sharma in MRCP Part 2 Best of Five Practice Questions, 2018
A 19-year-old female patient presents with gross oedema and frothy urine. She is investigated and is found to have a serum albumin of 10 g/L and heavy proteinuria of 11.5 g/day with a cholesterol of 9 mmol/L. She undergoes a renal biopsy and a diagnosis of minimal change nephropathy is made. She initially goes into remission with oral prednisolone but, on withdrawal of steroids, she is readmitted with a painful left leg and further significant oedema of the arms, legs and face. A deep vein thrombosis extending to her left external iliac vein is diagnosed on Doppler ultrasonography. She is commenced on intravenous heparin (5000 U intravenous bolus followed by infusion of 15 U/kg/h increased after six hours to 18 U/kg/h) but her left leg swelling fails to respond and 36 hours later the following results are obtained:
Short-term effects of first trimester low-dose aspirin therapy on uterine artery flow in women at high risk for preeclampsia
Published in Journal of Obstetrics and Gynaecology, 2022
Emine Eda Akalin, Munip Akalin, Habibe Ayvaci Tasan, Kazibe Koyuncu
Preeclampsia is one of the most important causes of maternal and perinatal morbidity and mortality and complicates 4.6% of pregnancies worldwide (Abalos et al. 2013). Preeclampsia may cause serious maternal life-threatening complications as well as intrauterine growth restriction and iatrogenic preterm birth (Abalos et al. 2014). The aetiology of preeclampsia is still not clearly explained. Endothelial dysfunction and defective trophoblast differentiation have been shown to cause most of the findings (Susan et al. 2009). Defective trophoblast differentiation causes inadequate invasion of extravillous trophoblasts and endothelial dysfunction may lead to high resistance in uterine arteries (Ridder et al. 2019). Pulsed wave Doppler ultrasonography is a common technique to detect abnormal blood flow in uterine arteries (Clark et al. 2018). It is believed that in early gestational weeks, uterine artery Doppler measurements may partially meet the requirements of a screening test for preeclampsia, because it is simple, harmless and fast. In pregnancies complicated by preeclampsia, there is a high mean pulsatility index with an early diastolic notch in uterine artery Doppler flow as a result of increased resistance in the uterine artery (Harrington et al. 1991; Bower et al. 1993). Although early gestational week uterine artery Doppler screening has been used in some studies to determine the risk of preeclampsia, it is a method with a high negative predictive value (Rolnik et al. 2017).
The Relationship between Ocular Vascular Changes and the Levels of Malondialdehyde and Vascular Endothelial Growth Factor in Patients with Inflammatory Bowel Disease
Published in Ocular Immunology and Inflammation, 2021
Nilay Sengul Samanci, Sule Poturoglu, Cesur Samanci, Fethi Emre Ustabasioglu, Macit Koldas, Ali Erkan Duman, Aslı Ciftcibası Ormeci
We studied 56 eyes of 28 patients (17 females) with CD, 62 eyes of 31 patients (12 females) with UC, and 68 eyes of 34 healthy age-matched control subjects (23 females). Males were more common in the UC group (p = .038). The mean age of CD patients was 37.0 ± 10.8 years (18–62), that of UC patients was 41.0 ± 13.6 years (24–80), and that of the control group was 37.0 ± 8.7 years (19–53). The average age did not significantly differ among the groups (p = .612). The mean time that elapsed after CD diagnosis was 8.2 ± 6.8 years (1–30) and that after UC diagnosis was 3.1 ± 2.4 years (1–12). The extent of disease activity in both patient groups was mild to moderate. Table 1 summarizes the Doppler ultrasonography measurements. Significant among-group differences were evident except in terms of eye diameter.
Intrarenal resistive index conundrum: systemic atherosclerosis versus renal arteriolosclerosis
Published in Renal Failure, 2019
Gabriel Ștefan, Cosmin Florescu, Alexandru-Anton Sabo, Simona Stancu, Gabriel Mircescu
For Doppler ultrasonography examination a real-time ultrasound device with color Doppler capacity (Samsung HM70A) and a 3.5 MHz convex-type transducer (CA1-7AD) were used. The examination was performed early in the morning, after 8-h overnight fast, with the patient in supine position and after at least 15 min rest. The signals were obtained from interlobar and arcuate arteries in the upper, middle, and lower parts of the kidney. The RRI was calculated as [(peak- systolic velocity – end-diastolic velocity)/peak systolic velocity]. The RRI value for each kidney was the mean of all 6 measurements. A mean RRI value was obtained for each patient by averaging the two kidneys’ mean RRIs (Spearman correlation coefficient between the two kidneys RRI measurements was 0,95, p < 0.001). The use of antihypertensive medication was not suspended before RRI measurement. Ultrasonographic examination that included RRI assessment was performed the day before the renal biopsy. In order to avoid inter-observer variability, all Doppler examinations were performed by the same examiner who was unaware of the study or the clinical details of the patients.
Related Knowledge Centers
- Body Fluid
- Internal Jugular Vein
- Jugular Venous Pressure
- Portal Hypertension
- Tissue
- Atrium
- Medical Ultrasound
- Medical Imaging
- Ultrasonic Transducer
- Transcranial Doppler