摘要 :
Power Doppler (PD) is used widely in musculoskeletal ultrasound, especially in the assessment of structures for evidence of
inflammation and in evaluating soft tissue neoplasms. We reinforce and delineate the three cardinal princ...
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Power Doppler (PD) is used widely in musculoskeletal ultrasound, especially in the assessment of structures for evidence of
inflammation and in evaluating soft tissue neoplasms. We reinforce and delineate the three cardinal principles of optimising
PD assessment in order to avoid false positive or false negative results; namely (1) Optimal gain settings (2) Adequate
transducer pressure, and (3) Proper patient/anatomical structure-of-interest positioning with complete tissue relaxation.
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Objective:The goal of this work was to develop a clinically applicable method for non-invasive acoustic determination of hematocrit in vivo.Methods:The value of hematocrit (HCT) was determined initially in vitro from the pulse-ech...
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Objective:The goal of this work was to develop a clinically applicable method for non-invasive acoustic determination of hematocrit in vivo.Methods:The value of hematocrit (HCT) was determined initially in vitro from the pulse-echo measurements of acoustic attenuation.The testing was carried out using a laboratory setup with ultrasound transducer operating at 20 MHz and employing human blood samples at the temperature of 37 deg C.The attenuation coefficient measurements in blood in vitro and in vivo were implemented using multi-gated (128-gates),20 MHz pulse Doppler flow meter.The Doppler signal was recorded in the brachial artery.Both in vitro and in vivo HCT data were compared with those obtained using widely accepted,conventional centrifuge method.Results:The attenuation coefficient in vitro was determined from the measurements of 168 samples with hematocrit varying between 23.9 and 51.6%.Those experiments indicated that the coefficient increased linearly with hematocrit.The HCT value was obtained from the 20 MHz data using regression analysis.The attenuation (() was determined as a 42.14+1.02 centre dot HCT (Np/m).The corresponding standard deviation (SD),and the correlation coefficient were calculated as SD=2.4 Np/m,and R=0.9,(p < 0.001 ),respectively The absolute accuracy of in vivo measurements in the brachial artery was determined to be within +-5% HCT.Conclusions:The method proposed appears to be promising for in vivo determination of hematocrit as 5% error is adequate to monitor changes in patients in shock or during dialysis.It was found that the multigate system largely simplified the placement of an ultrasonic probing beam in the center of the blood vessel.Current work focuses on enhancing the method's applicability to arbitrary selected vessels and reducing the HCT measurement error to well below 5%.
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The concept of neovascularization in tendinopathy seems to have gained nearly mythological proportions and quasi-religious state: it is considered of diagnostic and prognostic value, related to clinical outcome, and the exclusive ...
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The concept of neovascularization in tendinopathy seems to have gained nearly mythological proportions and quasi-religious state: it is considered of diagnostic and prognostic value, related to clinical outcome, and the exclusive target of some therapeutic interventions. However, we question whether these assumptions are based on scientific evidence, and we come to the conclusion that, in the light of recent well-performed research, it seems that detecting neovessels has no additional value for the diagnosis, no firmly confirmed prognostic value, and no proven relation with symptoms. The role of neovascularization in this field should be re-thought. Level of evidence V.
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This article discusses the utilization of Doppler sonography in the breast. The article encompasses the use of Doppler sonography to differentiate benign from malignant lesions to assess neovascularity in tumors to assess the resp...
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This article discusses the utilization of Doppler sonography in the breast. The article encompasses the use of Doppler sonography to differentiate benign from malignant lesions to assess neovascularity in tumors to assess the response after chemotherapy and to differentiate benign from malignant lymph nodes based on various blood-flow patterns. The discussion also incorporates the recent advances in the current literature regarding the value of techniques such as sonoelastography, 3D Doppler imaging and the use of tissue harmonics. While mammography remains the prime modality to evaluate breast lesions, advances in the field of ultrasound demonstrate promising results and future hope for a more specific role of ultrasound in this cause.
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Doppler ultrasound is able to visualize blood flow by the change in frequency (Doppler shift) of sound waves that are reflected by moving blood cells inside the vessels (Doppler effect). Since hyperemia caused by vasodilation and ...
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Doppler ultrasound is able to visualize blood flow by the change in frequency (Doppler shift) of sound waves that are reflected by moving blood cells inside the vessels (Doppler effect). Since hyperemia caused by vasodilation and angiogenesis can be the earliest detectable pathologic changes in the beginning of synovitis, Doppler ultrasonography can be used to assess inflammatory activity. In addition, several studies demonstrate a strong correlation between MRI as well as histological findings (blood vessel density) and Doppler sonographic visualization of synovial perf usion. To achieve this goal, equipment settings must be adapted to slow blood flow in very small blood vessels to reach an appropriate imaging quality. Color and power Doppler ultrasound depict different grades of intra-articular and peritendineous blood flow, which allows an estimation of inflammatory activity and is a helpful tool for the monitoring of rheumatic diseases during follow-up.
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A 10 MHz pulsed Doppler ultrasound was applied to measure both Doppler power and Doppler velocity from stirred porcine blood of various hematocrits for assessing variations in blood properties during blood coagulation and clot for...
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A 10 MHz pulsed Doppler ultrasound was applied to measure both Doppler power and Doppler velocity from stirred porcine blood of various hematocrits for assessing variations in blood properties during blood coagulation and clot formation. For each measurement, blood was recalcified by adding calcium chloride solution. Results obtained from original blood at hematocrits of 25, 35, 45, and 55% showed that the mean Doppler power and Doppler velocity were respectively equal to 40.2, 38.5, 38.1, and 37.6dB, and 24.6, 21.4, 20.0, and 19.6cm/s. The variations in blood properties during blood coagulation caused Doppler power and velocity to fluctuate markedly. As the clot was formed, Doppler power was increased by approximately 5.5 dB and velocity was decreased to approximately 5.2 cm/s. These studies validated the suggestion that Doppler ultrasound is a feasible and sensitive means to quantify blood properties during blood coagulation and clot formation.
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Objective. To determine combined evaluation of musculoskeletal ultrasonography (MSUS) and power Doppler (PD) signals, anti-citrullinated peptide antibody (ACPA), and other clinical findings improve the prediction of joint destruct...
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Objective. To determine combined evaluation of musculoskeletal ultrasonography (MSUS) and power Doppler (PD) signals, anti-citrullinated peptide antibody (ACPA), and other clinical findings improve the prediction of joint destruction in rheumatoid arthritis (RA).
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Objectives. To investigate power Doppler (PD) signal, grade and location and their association with radiographic progression in RA patients in remission.
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Ways to measure blood perfusion using ultrasound techniques such as continuous-wave Doppler, pulsed Doppler, colour Doppler and power Doppler will be reviewed. From a certain standpoint, blood perfusion may be defined as the diffe...
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Ways to measure blood perfusion using ultrasound techniques such as continuous-wave Doppler, pulsed Doppler, colour Doppler and power Doppler will be reviewed. From a certain standpoint, blood perfusion may be defined as the difference betweenarterial inflow and arterial outflow from a considered volume, i.e. capillary flow. The low velocities and small blood volumes involved make the signal-to-noise ratio, dynamic range and frequency resolution critical factors in the detection system.Another limiting factor is tissue motion which obscures the blood signal. Perfusion may still under certain conditions be estimated with the first moment of the Doppler power spectrum, as obtained with any Doppler ultrasound method. Modern flow mappingtechniques also make it possible to estimate perfusion by counting the number of pixels that indicate flow, but low flow velocities cannot be included in the estimate. Future high-frequency systems may. however. provide very detailed images of minute flow distributions in superficial layers. Contrast agents are widely used today to enhance the blood signal, and a technique named harmonic imaging can suppress movement artefacts from surrounding tissue. Transient signals from disrupting contrast agentparticles in an ultrasound field can potentially be used for perfusion quantification. Future developments to extract the blood flow signal from its noisy environment, aside from contrast agents. may he multiple sample volumes, frequency compoundingand/or improved signal processing. The lack of an adequate perfusion phantom for verification of measurements of microcirculatory flow becomes, however, more apparent with improved detectability of slow flows.
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