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Stroke and Transient Ischemic Attacks of the Brain and Eye
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
Figures 12.162—12.164 display an example of a stenosis in the proximal ICA, with resulting increased velocity. Advantages of carotid Doppler ultrasonography include safety, relatively low cost, portability, and reasonable ability to detect a hemodynamically significant stenosis.
How Does Ultrasound Work?
Published in John McCafferty, James M Forsyth, 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).
Venous Thrombosis
Published in Hau C. Kwaan, Meyer M. Samama, Clinical Thrombosis, 2019
Gary E. Raskob, Russell D. Hull
Doppler ultrasound has both advantages and disadvantages over IPG. It can be performed more conveniently and rapidly than IPG and is less expensive. It may be difficult to maintain a high degree of precision with Doppler ultrasonography, however, because the interpretation of the audio signal requires an experienced observer. Unfortunately, it has not been possible to record the information provided by the audio signal as a permanent tracing without considerable loss. Thus, at present, the interpretation of Doppler ultrasonography is subjective, and requires considerable skill and experience to perform reliably, in contrast to IPG, which is both objective and precise. In skilled hands, Doppler ultrasonography is almost as sensitive for symptomatic proximal vein thrombosis as IPG and it is more sensitive to symptomatic calf vein thrombosis, since it detects approximately 50% of such thrombi.
Ultrasound centre frequency shifts as a novel approach for diagnosing giant cell arteritis
Published in Scandinavian Journal of Rheumatology, 2023
M Naumovska, R Sheikh, J Albinsson, B Hammar, U Dahlstrand, M Malmjsö, T Erlöv
Colour Doppler ultrasonography is associated with other limitations. False-positive results are sometimes seen in cases of atherosclerosis (32), and false-negative results are seen in individuals who have periadventitial small-vessel vasculitis or vasa vasorum vasculitis, in contrast to a more classic transmural pattern (33). Indeed, patients with atherosclerosis often appear in the investigation for GCA. In the present study, the patients with negative biopsies for GCA had a higher incidence of risk factors for atherosclerosis (e.g. hypertension and diabetes mellitus), which is probably an effect of these patients being more often subject to investigation as the symptoms may mimic those of GCA (e.g. loss of vision and low pulsatility of the temporal artery on clinical examination). Unfortunately, subgroup analysis of the CFS data was not possible in the present study owing to the limited sample size. The effect of atherosclerosis on CFS may be an important consideration in future studies directed towards clinical implementation.
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.