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Sample records for blood flow measurement

  1. Endovascular blood flow measurement system

    Science.gov (United States)

    Khe, A. K.; Cherevko, A. A.; Chupakhin, A. P.; Krivoshapkin, A. L.; Orlov, K. Yu

    2016-06-01

    In this paper an endovascular measurement system used for intraoperative cerebral blood flow monitoring is described. The system is based on a Volcano ComboMap Pressure and Flow System extended with analogue-to-digital converter and PC laptop. A series of measurements performed in patients with cerebrovascular pathologies allows us to introduce “velocity-pressure” and “flow rate-energy flow rate” diagrams as important characteristics of the blood flow. The measurement system presented here can be used as an additional instrument in neurosurgery for assessment and monitoring of the operation procedure. Clinical data obtained with the system are used for construction of mathematical models and patient-specific simulations. The monitoring of the blood flow parameters during endovascular interventions was approved by the Ethics Committee at the Meshalkin Novosibirsk Research Institute of Circulation Pathology and included in certain surgical protocols for pre-, intra- and postoperative examinations.

  2. Laser Doppler measurement of cutaneous blood flow

    International Nuclear Information System (INIS)

    Laser Doppler velocimetry is an instrument system which has only recently been applied to the evaluation and quantitation of perfusion in the micro-vascular bed. The instrument is based on the Doppler principle, but uses low power laser light rather than the more commonly used ultrasound, and has a sample volume of approximately 1 mm/sup 3/. As it is non-invasive, it can be used on any skin surface or exposed microvascular bed and provides a continuous semi-quantitative measure of microcirculatory perfusion, it has a number of advantages as compared to other cutaneous blood flow measurement techniques. Initial studies have shown that it is easily used, and it has demonstrated good correlation with both xenon radio-isotope clearance and microsphere deposition techniques. Areas of current evaluation and utilization are in most major areas of medicine and surgery and include plastic, vascular and orthopaedic surgery, dermatology, gastro-enterology, rheumatology, burns and anaesthesiology

  3. Our experience of blood flow measurements using radioactive tracers

    International Nuclear Information System (INIS)

    A critical study of blood flow measuring methods is proposed. After a review of the various diffusible and non-diffusible radioactive tracers and the corresponding detector systems, the principles which allow to measure blood flow from the data so obtained, are studied. There is a different principle of flow measurement for each type of tracer. The theory of flow measurement using non-diffusible tracers (human serum albumin labelled with 131I or sup(99m)Tc, 113In-labelled siderophiline) and its application to cardiac flow measurement are described first. Then the theory of flow measurement using diffusible tracers (133Xe, 85Kr) and its application to measurement of blood flow through tissues (muscles and kidney particularly) are described. A personal experience of this various flow measurements is reported. The results obtained, the difficulties encountered and the improvments proposed are developed

  4. Aortic blood flow subtraction: an alternative method for measuring total renal blood flow in conscious dogs

    DEFF Research Database (Denmark)

    Sandgaard, N C F; Andersen, J L; Holstein-Rathlou, N-H;

    2002-01-01

    We have measured total renal blood flow (TRBF) as the difference between signals from ultrasound flow probes implanted around the aorta above and below the renal arteries. The repeatability of the method was investigated by repeated, continuous infusions of angiotensin II and endothelin-1 seven...

  5. Hall effect in electrolyte flow measurements: introduction to blood flow measurements.

    Science.gov (United States)

    Szwast, Maciej; Piatkiewicz, Wojciech

    2012-06-01

    The Hall effect has been applied to electrolyte flow measurement. It has been proven that Hall voltage does not depend on electrolyte concentration; however, there is a linear relationship between Hall voltage and flow velocity. Obtained results for electrolyte allow us to suppose that Hall effect can be used to determine blood flow. Research on blood will be conducted as the next step. PMID:22145845

  6. Measurement of tumor blood flow following neutron irradiation

    International Nuclear Information System (INIS)

    Clinical oncologists and cancer researchers benefit from information on the vascularization or non-vascularization of solid tumors because of blood flow's influence on three popular treatment types: hyperthermia therapy, radiotherapy, and chemotherapy. The objective of this research is the development of a clinically useful tumor blood flow measurements technique. The designed technique is sensitive, has good spatial resolution, in non-invasive and presents no risk to the patient beyond his usual treatment. Tumor blood flow was determined by measuring the washout of positron emitting isotopes created through neutron therapy treatment. In order to do this, several technical and scientific questions were addressed first. These questions have been answered through both theoretical calculation and measurement. The first question was answered through the measurement of macroscopic cross sections for the predominant nuclear reactions in the body. These results correlate well with an independent mathematical prediction of tissue activation and measurements of mouse spleen neutron activation. The second question was addressed by performing cell suspension and protein precipitation techniques on neutron activated mouse spleens. The third and final question was answered by using first physical principles to develop a model mimicking the blood flow system and measurement technique. In a final set of experiments, the above were applied to flow models and animals. The ultimate aim of this project is to apply its methodology to neutron therapy patients

  7. [The landmarks of the measurement of cerebral blood flow].

    Science.gov (United States)

    István, Nyáry

    2008-01-30

    History of the measurement of local cerebral blood flow may cover a period of one and a half centuries. Parallel forthcoming of both theoretical and technical development were the key elements of ensuing progress resulting in the present state, when by the aid of in vivo blood flow and metabolic maps, we can visualize locales of brain functioning and their interconnections. Two theoretical landmarks should be mentioned in this historic process. First, the work of Adolf Fick, as the starter of quantitative measurements in this field, and Seymour Kety's model of a single, homogenously perfused tissue element. The solution of this model, in the form of Kety's equation is still fundamental to present day blood flow mapping techniques. Among the numerous investigators over the past years, two Hungarian scientist can be named as major contributors. Kálmán Sántha made substantial studies with continuous registration of local cerebral blood flow by the aid of thermocouples, while Emil P6sztor invented the hydrogen clearance method for the measurement of local cerebral blood flow both in human and in animal studies.

  8. Accurate blood flow measurements: are artificial tracers necessary?

    Directory of Open Access Journals (Sweden)

    Christian Poelma

    Full Text Available Imaging-based blood flow measurement techniques, such as particle image velocimetry, have become an important tool in cardiovascular research. They provide quantitative information about blood flow, which benefits applications ranging from developmental biology to tumor perfusion studies. Studies using these methods can be classified based on whether they use artificial tracers or red blood cells to visualize the fluid motion. We here present the first direct comparison in vivo of both methods. For high magnification cases, the experiments using red blood cells strongly underestimate the flow (up to 50% in the present case, as compared to the tracer results. For medium magnification cases, the results from both methods are indistinguishable as they give the same underestimation of the real velocities (approximately 33%, based on in vitro reference measurements. These results suggest that flow characteristics reported in literature cannot be compared without a careful evaluation of the imaging characteristics. A method to predict the expected flow averaging behavior for a particular facility is presented.

  9. Simple technique for measuring relative renal blood flow

    International Nuclear Information System (INIS)

    To determine whether externally monitored early renal uptake of 131I-hippurate is proportional to renal blood flow, the renal uptake of 131-hippurate at 1 to 2 min after injection was compared with the renal accumulation of radioactive carbonized microspheres in dogs. A renal artery catheter equipped with a balloon was used to decrease renal blood flow unilaterally. One minute after the intravenous injection of 100 μCi of 131I-hippurate, about 1 μCi of either 85Sr- or 95Nb-labeled carbon microspheres was injected into the left ventricle. Radioactivity was measured over both kidneys. The total radioactivity within each kidney region of interest was corrected for background and integrated over the 1 to 2 min interval after injection. Thirteen measurements of relative renal blood flow were made for seven dogs. The dogs were then killed and both kidneys were excised and counted for the radioactivity of the microspheres. The 1 to 2-min relative renal uptake of 131I-hippurate correlated well with relative microsphere uptake, suggesting that relative renal blood flow can be simply determined from the external measurements of renal uptake of 131I-hippurate

  10. Methods for blood flow measurements using ultrasound contrast agents

    Science.gov (United States)

    Fowlkes, J. Brian

    2003-10-01

    Blood flow measurements using ultrasound contrast agents are being investigated for myocardial perfusion and more recently in other organ systems. The methods are based largely on the relative increase in echogenicity due to the concentration of bubbles present in the ultrasound beam. In the simplest form, regional differences in blood volume can be inferred but the possibility exists to extract perfusion from the transit of contrast agent through tissue. Perfusion measurements rely on determining the flux of blood through a tissue volume and as such require knowledge of the fractional blood volume (FBV), i.e., ml blood/g tissue and the rate of exchange, commonly measured as the mean transit time (MTT). This presentation will discuss methods of determining each of these values and their combination to estimate tissue perfusion. Underlying principles of indicator-dilution theory will be provided in the context of ultrasound contrast agents. Current methods for determining MTT will include imaging of the intravenous bolus, in-plane contrast disruption with interval and real-time contrast recovery imaging, and control of contrast agent flow using arterial disruption (contrast interruption). The advantages and limitations of the methods will be examined along with current applications. [Work supported in part by NIH.

  11. Methods for measurement of cerebral blood flow in man

    DEFF Research Database (Denmark)

    Lassen, N A

    1976-01-01

    A survey of the currently available methods for the measurement of cerebral blood flow in man is given. Many of the clinically important brain diseases such as tumors, stroke, brain trauma or epilepsy entail focal or regional flow alterations. Therefore a special emphasis is placed on methods...... information both on spatial localization and, especially, on ischemic areas. The most promising is computer-assisted axial tomography with freely diffusible radioactive isotopes or with x-rays using an intra-arterial injection of contrast. But, the available techniques are still too slow: in order to measure...

  12. Pulmonary blood flow distribution measured by radionuclide computed tomography

    International Nuclear Information System (INIS)

    Distributions of pulmonary blood flow per unit lung volume were measured in sitting patients with a radionuclide computed tomography (RCT) by intravenously administered Tc-99m macroaggregates of human serum albumin (MAA). Four different types of distribution were distinguished, among which a group referred as type 2 had a three zonal blood flow distribution as previously reported (West and co-workers, 1964). The pulmonary arterial pressure (Pa) and the venous pressure (Pv) were determined in this group of distribution. These values showed satifactory agreements with the pulmonary artery pressure (Par) and the capillary wedged pressure (Pcw) measured by Swan-Ganz catheter in eighteen supine patients. Those good correlations enable to establish a noninvasive methodology for measurement of pulmonary vascular pressures

  13. Measuring bovine mammary gland blood flow using a transit time ultrasonic flow probe.

    Science.gov (United States)

    Gorewit, R C; Aromando, M C; Bristol, D G

    1989-07-01

    Lactating cattle were used to validate a transit time ultrasonic blood flow metering system for measuring mammary gland arterial blood flow. Blood flow probes were surgically placed around the right external pudic artery. An electromagnetic flow probe was implanted in tandem with the ultrasonic probe in two cows for comparative measurements. The absolute accuracy of the implanted flow probes was assessed in vivo by mechanical means on anesthetized cows after 2 to 3 wk of implantation. The zero offset of the ultrasonic probes ranged from -12 to 8 ml/min. When the ultrasonic probe was properly implanted, the slopes of the calibration curves were linear and ranged from .92 to .95, tracking absolute flow to within 8%. The transit time instrument's performance was examined under a variety of physiological conditions. These included milking and hormone injections. The transit time ultrasonic flow meter accurately measured physiological changes in mammary arterial blood flow in chronically prepared conscious cattle. Blood flow increased 29% during milking. Epinephrine decreased mammary blood flow by 90 to 95%. Oxytocin doses increased mammary blood flow by 15 to 24%. PMID:2674232

  14. Pressure Gradient Estimation Based on Ultrasonic Blood Flow Measurement

    Science.gov (United States)

    Nitta, Naotaka; Homma, Kazuhiro; Shiina, Tsuyoshi

    2006-05-01

    Mechanical load to the blood vessel wall, such as shear stress and pressure, which occurs in blood flow dynamics, contribute greatly to plaque rupture in arteriosclerosis and to biochemical activation of endothelial cells. Therefore, noninvasive estimations of these mechanical loads are able to provide useful information for the prevention of vascular diseases. Although the pressure is the dominant component of mechanical load, for practical purposes, the pressure gradient is also often important. So far, we have investigated the estimation of the kinematic viscosity coefficient using a combination of the Navier-Stokes equations and ultrasonic velocity measurement. In this paper, a method for pressure gradient estimation using the estimated kinematic viscosity coefficient is proposed. The validity of the proposed method was investigated on the basis of the analysis with the data obtained by computer simulation and a flow phantom experiment. These results revealed that the proposed method can provide a valid estimation of the pressure gradient.

  15. Measurement of regional cerebral blood flow by positron emission tomography

    International Nuclear Information System (INIS)

    The principal advantage of positron emission tomography over other methods for measuring cerebral blood flow stems from the accurate, quantitative three-dimensional measurements of regional brain radioactivity that are possible with this technique. As a result, accurate quantitative measurements of regional cerebral blood flow can be obtained for both superficial and deep cerebral structures. The value of PET for investigating central nervous system physiology and pathology extends far beyond this, however. Through the use of different radiotracers and appropriate mathematical models, PET can be applied to the measurement of a wide variety of physiologic variables. Measurements of rCBF tell only part of the story. Experience with PET and with a variety of other techniques has taught us that rCBF is at times a poor indicator of the metabolic, functional, and biochemical status of cerebral tissue. It is only by understanding the interaction of all of these factors that our understanding of neurologic disease can advance. It is in the investigation of these complex relationships that the real value of PET resides

  16. Nephron blood flow dynamics measured by laser speckle contrast imaging

    DEFF Research Database (Denmark)

    von Holstein-Rathlou, Niels-Henrik; Sosnovtseva, Olga V; Pavlov, Alexey N;

    2011-01-01

    Tubuloglomerular feedback (TGF) has an important role in autoregulation of renal blood flow and glomerular filtration rate (GFR). Because of the characteristics of signal transmission in the feedback loop, the TGF undergoes self-sustained oscillations in single-nephron blood flow, GFR, and tubula...

  17. In vitro validation of volumetric blood flow measurement using Doppler flow wire.

    Science.gov (United States)

    Jenni, R; Kaufmann, P A; Jiang, Z; Attenhofer, C; Linka, A; Mandinov, L

    2000-10-01

    Determination of any volumetric blood flow requires assessment of mean blood flow velocity and vessel cross-sectional area. For evaluation of coronary blood flow and flow reserve, however, assessment of average peak velocity alone is widely used, but changes in velocity profile and vessel area are not taken into account. We studied the feasibility of a new method for calculation of volumetric blood flow by Doppler power using a Doppler flow wire. An in vitro model with serially connected silicone tubes of known lumen diameters (1.5, 2.0, 2.5, 3.0, 3.5 and 4.0 mm) and pulsatile blood flow ranging from 10 to 200 mL/min was used. A Doppler flow wire was connected to a commercially available Doppler system (FloMap(R), Cardiometrics) for online calculation of the zeroth (M(0)) and the first (M(1)) Doppler moment, as well as mean flow velocity (V(m)). Two different groups of sample volumes (at different gate depths) were used: 1. two proximal sample volumes lying completely within the vessel were required to evaluate the effect of scattering and attenuation on Doppler power, and 2. distal sample volumes intersecting completely the vessel lumen to assess the vessel cross-sectional area. Area (using M(0)) and V(m) (using M(1)/M(0)) obtained from the distal gates were corrected for scattering and attenuation by the data obtained from the proximal gates, allowing calculation of absolute volumetric flow. These results were compared to the respective time collected flow. Correlation between time collected and Doppler-derived flow measurements was 0.98 (p measurements in each individual tube. The mean paired flow difference between the two techniques was 1.5 +/- 9.0 mL/min (ns). Direct volumetric blood flow measurement from received Doppler power using a Doppler flow wire system is feasible. This technique may potentially be of great clinical value because it allows an accurate assessment of coronary flow and flow reserve with a commercially available flow wire system. PMID

  18. Occlusion cuff for routine measurement of digital blood pressure and blood flow

    DEFF Research Database (Denmark)

    Lassen, N A; Krähenbühl, B; Hirai, M

    1977-01-01

    A miniaturized blood pressure cuff made of plastic material and applicable to fingers and toes is described. The cuff was compared to rubber cuffs and to bladder-free cuffs. It was found to be more reliable than the former type and much easier to use than the latter type. It is recommended for us...... in conjunction with a mercury-in-Silastic strain gauge for routine measurement of digital blood pressure and blood flow in patients with arterial disease.......A miniaturized blood pressure cuff made of plastic material and applicable to fingers and toes is described. The cuff was compared to rubber cuffs and to bladder-free cuffs. It was found to be more reliable than the former type and much easier to use than the latter type. It is recommended for use...

  19. Determining tumor blood flow parameters from dynamic image measurements

    Science.gov (United States)

    Libertini, Jessica M.

    2008-11-01

    Many recent cancer treatments focus on preventing angiogenesis, the process by which a tumor promotes the growth of large and efficient capillary beds for the increased nourishment required to support the tumor's rapid growth[l]. To measure the efficacy of these treatments in a timely fashion, there is an interest in using data from dynamic sequences of contrast-enhanced medical imaging, such as MRI and CT, to measure blood flow parameters such as perfusion, permeability-surface-area product, and the relative volumes of the plasma and extracellular-extravascular space. Starting with a two compartment model presented by the radiology community[2], this work challenges the application of a simplification to this problem, which was originally developed to model capillary reuptake[3]. While the primary result of this work is the demonstration of the inaccuracy of this simplification, the remainder of the paper is dedicated to presenting alternative methods for calculating the perfusion and plasma volume coefficients. These methods are applied to model data sets based on real patient data, and preliminary results are presented.

  20. Determining tumor blood flow parameters from dynamic image measurements

    Energy Technology Data Exchange (ETDEWEB)

    Libertini, Jessica M [Division of Applied Mathematics, Brown University, Providence, Rhode Island 02906 (United States)], E-mail: Jessica_Libertini@brown.edu

    2008-11-01

    Many recent cancer treatments focus on preventing angiogenesis, the process by which a tumor promotes the growth of large and efficient capillary beds for the increased nourishment required to support the tumor's rapid growth. To measure the efficacy of these treatments in a timely fashion, there is an interest in using data from dynamic sequences of contrast-enhanced medical imaging, such as MRI and CT, to measure blood flow parameters such as perfusion, permeability-surface-area product, and the relative volumes of the plasma and extracellular-extravascular space. Starting with a two compartment model presented by the radiology community, this work challenges the application of a simplification to this problem, which was originally developed to model capillary reuptake. While the primary result of this work is the demonstration of the inaccuracy of this simplification, the remainder of the paper is dedicated to presenting alternative methods for calculating the perfusion and plasma volume coefficients. These methods are applied to model data sets based on real patient data, and preliminary results are presented.

  1. Placental blood flow measurements with radioisotopes in the pregnant guinea pig

    International Nuclear Information System (INIS)

    In 15 pregnant guinea pigs near term the blood flow (BF) of the myometrium and the placenta as well as the cardiac output were measured with 99Tcsup(m)-labelled microspheres. In front of one placenta the clearance of 133Xe was estimated in the same animal. For the 133Xe measurement a theoretical concept is presented. The mean placental BF is 105ml/(minx100g)(SD:84) for 99Tcsup(m) and 244(SD:80)ml/(minx100g) for 133Xe. The difference in both flow values is assumed to be related to foetal placental BF. The placental blood flow is also related to the location of the placenta in the uterine horn. The ratio of myometrial blood flow to placental blood flow decreased with an increase in the mean arterial blood pressure. The measurements are a preliminary report of an attempt to compare two different methods in measuring placental blood flow. (author)

  2. Validation of an optical flow algorithm to measure blood flow waveforms in arteries using dynamic digital x-ray images

    Science.gov (United States)

    Rhode, Kawal; Lambrou, Tryphon; Hawkes, David J.; Hamilton, George; Seifalian, Alexander M.

    2000-06-01

    We have developed a weighted optical flow algorithm for the extraction of instantaneous blood velocity from dynamic digital x-ray images of blood vessels. We have carried out in- vitro validation of this technique. A pulsatile physiological blood flow circuit was constructed using sections of silicone tubing to simulate blood vessels with whole blood as the fluid. Instantaneous recording of flow from an electromagnetic flow meter (EMF) provided the gold standard measurement. Biplanar dynamic digital x-ray images of the blood vessel with injection of contrast medium were acquired at 25 fps using a PC frame capture card. Imaging of a Perspex calibration cube allowed 3D reconstruction of the vessel and determination of true dimensions. Blood flow waveforms were calculated off-line on a Sun workstation using the new algorithm. The correlation coefficient between instantaneous blood flow values obtained from the EMF and the x-ray method was r equals 0.871, n equals 1184, p less than 0.0001. The correlation coefficient for average blood flow was r equals 0.898, n equals 16, p less than 0.001. We have successfully demonstrated that our new algorithm can measure pulsatile blood flow in a vessel phantom. We aim to use this algorithm to measure blood flow clinically in patients undergoing vascular interventional procedures.

  3. Simple Radiowave-Based Method For Measuring Peripheral Blood Flow Project

    Science.gov (United States)

    Oliva-Buisson, Yvette J.

    2014-01-01

    Project objective is to design small radio frequency based flow probes for the measurement of blood flow velocity in peripheral arteries such as the femoral artery and middle cerebral artery. The result will be the technological capability to measure peripheral blood flow rates and flow changes during various environmental stressors such as microgravity without contact to the individual being monitored. This technology may also lead to an easier method of detecting venous gas emboli during extravehicular activities.

  4. Uteroplacental blood flow measured by placental scintigraphy during epidural anaesthesia for caesarean section

    Energy Technology Data Exchange (ETDEWEB)

    Skjoeldebrand, A.; Eklund, J.; Johansson, H.; Lunell, N.-O.; Nylund, L.; Sarby, B.; Thornstroem, S. (Departments of Anaesthesiology, Obstetrics and Gynaecology and Medical Physics, Karolinska Institute at Huddinge University Hospital, Stockholm (Sweden))

    1990-01-01

    The uteroplacental blood flow was measured before and during epidural anaesthesia for caesarean section in 11 woman. The blood flow was measured with dynamic placental scintigraphy. After an i.v. injection of indium-113m chloride, the gamma radiation over the placenta was recorded with a computer-linked scintillation camera. The uteroplacental blood flow could be calculated from the isotope accumulation curve. The anaesthesia was performed with bupivacaine plain 0.5%, 18-22 ml and a preload of a balanced electrolyte solution 10 ml/kg b.w. was given. The placental blood flow decreased in eight patients and increased in three with a median change of -21%, not being statistically significant. No correlation between maternal blood pressure and placental blood flow was found. (author).

  5. Use of phase-contrast magnetic resonance angiography to measure blood flow in the ophthalmic artery

    International Nuclear Information System (INIS)

    The aim of this study was to examine the usefulness of phase-contrast magnetic resonance (MR) angiography (PC-MRA) to measure blood flow in the ophthalmic artery. PC-MRA was performed in 16 volunteers with no ophthalmic abnormalities and measurement of blood flow based on the results was attempted. It was possible to measure blood flow in the ophthalmic artery using PC-MRA in all 16 volunteers. The mean (±1 standard deviation) velocity was 9.17±2.28 cm/second, peak systolic velocity was 16.69±3.33 cm/second, and end diastolic velocity was 3.69±2.44 cm/second. The resistivity index was 0.79±0.12, the pulsatility index was 1.49±0.41, and flow was 6.25±2.33 ml/minute. It was possible to identify the ophthalmic artery and a portion of the artery in which blood flow could be measured using MR imaging, a preliminary step to blood flow measurement using MR angiography. In addition to the velocity of blood flow in the ophthalmic artery, measurement of the amount of flow was possible with PC-MRA, which is one advantage of this method. (author)

  6. Anxiety and cerebral blood flow during behavioral challenge. Dissociation of central from peripheral and subjective measures

    Energy Technology Data Exchange (ETDEWEB)

    Zohar, J.; Insel, T.R.; Berman, K.F.; Foa, E.B.; Hill, J.L.; Weinberger, D.R.

    1989-06-01

    To investigate the relationship between anxiety and regional cerebral blood flow, we administered behavioral challenges to 10 patients with obsessive-compulsive disorder while measuring regional cerebral blood flow with the xenon 133 inhalation technique. Each patient was studied under three conditions: relaxation, imaginal flooding, and in vivo (actual) exposure to the phobic stimulus. Subjective anxiety, obsessive-compulsive ratings, and autonomic measures (heart rate, blood pressure) increased significantly, but respiratory rate and PCO/sub 2/ did not change across the three conditions. Regional cerebral blood flow increased slightly (in the temporal region) during imaginal flooding, but decreased markedly in several cortical regions during in vivo exposure, when anxiety was highest by subjective and peripheral autonomic measures. These results demonstrate that intense anxiety can be associated with decreased rather than increased cortical perfusion and that ostensibly related states of anxiety (eg, anticipatory and obsessional anxiety) may be associated with opposite effects on regional cerebral blood flow.

  7. Anxiety and cerebral blood flow during behavioral challenge. Dissociation of central from peripheral and subjective measures

    International Nuclear Information System (INIS)

    To investigate the relationship between anxiety and regional cerebral blood flow, we administered behavioral challenges to 10 patients with obsessive-compulsive disorder while measuring regional cerebral blood flow with the xenon 133 inhalation technique. Each patient was studied under three conditions: relaxation, imaginal flooding, and in vivo (actual) exposure to the phobic stimulus. Subjective anxiety, obsessive-compulsive ratings, and autonomic measures (heart rate, blood pressure) increased significantly, but respiratory rate and PCO2 did not change across the three conditions. Regional cerebral blood flow increased slightly (in the temporal region) during imaginal flooding, but decreased markedly in several cortical regions during in vivo exposure, when anxiety was highest by subjective and peripheral autonomic measures. These results demonstrate that intense anxiety can be associated with decreased rather than increased cortical perfusion and that ostensibly related states of anxiety (eg, anticipatory and obsessional anxiety) may be associated with opposite effects on regional cerebral blood flow

  8. Blood flow measurements during hemodialysis vascular access interventions - Catheter-based thermodilution or Doppler ultrasound?

    DEFF Research Database (Denmark)

    Heerwagen, Søren T; Hansen, Marc A; Schroeder, Torben V;

    2012-01-01

    Purpose: To test the clinical performance of catheter-based thermodilution and Doppler ultrasound of the feeding brachial artery for blood flow measurements during hemodialysis vascular access interventions.Methods: Thirty patients with arteriovenous fistulas who underwent 46 interventions had...

  9. MEASUREMENT OF REGIONAL BONE BLOOD FLOW IN THE CANINE MANDIBULAR RAMUS USING RADIOLABELLED TOAD RED BLOOD CELLS

    Institute of Scientific and Technical Information of China (English)

    毛驰; 王翰章

    1994-01-01

    Toad red blood cells were used to measure regional bone blood flow in the canine mandibular ramus.The blood cells were labelled with sodium pertechnetate and fixed in 10% formalin;they were 22×15 μm in size and had a specific gravity close to that of dog red blood cells.These cells had no discernible effect on systemic hemody-namics after injection,did not agglutinate,were well mixed and evenly distributed throughout the body,and were completely extracted in one circulation through the mandible.The mandibular ramus was divided into six regions,and the blood flow rates in each were found to be similar to those reported in previous studies with radiolabelled carbonized,microspheres.Furthermore,the blood flow distribution pattern of the mandibular ramus determined in this study was identical to that of our previous study using the bone-seeking radionuclide method.We suggest that radiolabelled toad red blood cells are an ideal marker for measuring regional blood flow in the canine mandible.

  10. Regional blood flow during exercise in humans measured by near-infrared spectroscopy and indocyanine green

    DEFF Research Database (Denmark)

    Boushel, R; Langberg, Henning; Olesen, J;

    2000-01-01

    Using near-infrared spectroscopy (NIRS) and the tracer indocyanine green (ICG), we quantified blood flow in calf muscle and around the Achilles tendon during plantar flexion (1-9 W). For comparison, blood flow in calf muscle was determined by dye dilution in combination with magnetic resonance...... imaging measures of muscle volume, and, for the peritendon region, blood flow was measured by (133)Xe washout. From rest to a peak load of 9 W, NIRS-ICG blood flow in calf muscle increased from 2.4+/-0.2 to 74+/-5 ml x 100 ml tissue(-1) x min(-1), similar to that measured by reverse dye (77+/-6 ml x 100...

  11. Measurement of cerebral blood flow rate and its relationship with brain function using optical coherence tomography

    Science.gov (United States)

    Liu, Jian; Wang, Yi; Zhao, Yuqian; Dou, Shidan; Ma, Yushu; Ma, Zhenhe

    2016-03-01

    Activity of brain neurons will lead to changes in local blood flow rate (BFR). Thus, it is important to measure the local BFR of cerebral cortex on research of neuron activity in vivo, such as rehabilitation evaluation after stroke, etc. Currently, laser Doppler flowmetry is commonly used for blood flow measurement, however, relatively low resolution limits its application. Optical coherence tomography (OCT) is a powerful noninvasive 3D imaging modality with high temporal and spatial resolutions. Furthermore, OCT can provide flow distribution image by calculating Doppler frequency shift which makes it possible for blood flow rate measurement. In this paper, we applied OCT to measure the blood flow rate of the primary motor cortex in rats. The animal was immobilized and anesthetized with isoflurane, an incision was made along the sagittal suture, and bone was exposed. A skull window was opened on the primary motor cortex. Then, blood flow rate changes in the primary motor cortex were monitored by our homemade spectral domain OCT with a stimulation of the passive movement of the front legs. Finally, we established the relationship between blood flow rate and the test design. The aim is to demonstrate the potential of OCT in the evaluation of cerebral cortex function.

  12. Quantitative blood flow measurements in the small animal cardiopulmonary system using digital subtraction angiography

    Energy Technology Data Exchange (ETDEWEB)

    Lin Mingde; Marshall, Craig T.; Qi, Yi; Johnston, Samuel M.; Badea, Cristian T.; Piantadosi, Claude A.; Johnson, G. Allan [Department of Radiology, Center for In Vivo Microscopy and Department of Biomedical Engineering, Duke University Medical Center, Box 3302, Durham, North Carolina 27710 (United States); Division of Pulmonary and Critical Care Medicine and Center for Hyperbaric Medicine and Environmental Physiology, Duke University Medical Center, Box 3823, Durham, North Carolina 27710 (United States); Department of Radiology, Center for In Vivo Microscopy, Duke University Medical Center, Box 3302, Durham, North Carolina 27710 (United States); Department of Radiology, Center for In Vivo Microscopy and Department of Biomedical Engineering, Duke University Medical Center, Box 3302, Durham, North Carolina 27710 (United States); Department of Radiology, Center for In Vivo Microscopy, Duke University Medical Center, Box 3302, Durham, North Carolina 27710 (United States); Division of Pulmonary and Critical Care Medicine and Center for Hyperbaric Medicine and Environmental Physiology, Duke University Medical Center, Box 3823, Durham, North Carolina 27710 (United States); Department of Radiology, Center for In Vivo Microscopy and Department of Biomedical Engineering, Duke University Medical Center, Box 3302, Durham, North Carolina 27710 (United States)

    2009-11-15

    Purpose: The use of preclinical rodent models of disease continues to grow because these models help elucidate pathogenic mechanisms and provide robust test beds for drug development. Among the major anatomic and physiologic indicators of disease progression and genetic or drug modification of responses are measurements of blood vessel caliber and flow. Moreover, cardiopulmonary blood flow is a critical indicator of gas exchange. Current methods of measuring cardiopulmonary blood flow suffer from some or all of the following limitations--they produce relative values, are limited to global measurements, do not provide vasculature visualization, are not able to measure acute changes, are invasive, or require euthanasia. Methods: In this study, high-spatial and high-temporal resolution x-ray digital subtraction angiography (DSA) was used to obtain vasculature visualization, quantitative blood flow in absolute metrics (ml/min instead of arbitrary units or velocity), and relative blood volume dynamics from discrete regions of interest on a pixel-by-pixel basis (100x100 {mu}m{sup 2}). Results: A series of calibrations linked the DSA flow measurements to standard physiological measurement using thermodilution and Fick's method for cardiac output (CO), which in eight anesthetized Fischer-344 rats was found to be 37.0{+-}5.1 ml/min. Phantom experiments were conducted to calibrate the radiographic density to vessel thickness, allowing a link of DSA cardiac output measurements to cardiopulmonary blood flow measurements in discrete regions of interest. The scaling factor linking relative DSA cardiac output measurements to the Fick's absolute measurements was found to be 18.90xCO{sub DSA}=CO{sub Fick}. Conclusions: This calibrated DSA approach allows repeated simultaneous visualization of vasculature and measurement of blood flow dynamics on a regional level in the living rat.

  13. Quantitative blood flow measurements in the small animal cardiopulmonary system using digital subtraction angiography

    International Nuclear Information System (INIS)

    Purpose: The use of preclinical rodent models of disease continues to grow because these models help elucidate pathogenic mechanisms and provide robust test beds for drug development. Among the major anatomic and physiologic indicators of disease progression and genetic or drug modification of responses are measurements of blood vessel caliber and flow. Moreover, cardiopulmonary blood flow is a critical indicator of gas exchange. Current methods of measuring cardiopulmonary blood flow suffer from some or all of the following limitations--they produce relative values, are limited to global measurements, do not provide vasculature visualization, are not able to measure acute changes, are invasive, or require euthanasia. Methods: In this study, high-spatial and high-temporal resolution x-ray digital subtraction angiography (DSA) was used to obtain vasculature visualization, quantitative blood flow in absolute metrics (ml/min instead of arbitrary units or velocity), and relative blood volume dynamics from discrete regions of interest on a pixel-by-pixel basis (100x100 μm2). Results: A series of calibrations linked the DSA flow measurements to standard physiological measurement using thermodilution and Fick's method for cardiac output (CO), which in eight anesthetized Fischer-344 rats was found to be 37.0±5.1 ml/min. Phantom experiments were conducted to calibrate the radiographic density to vessel thickness, allowing a link of DSA cardiac output measurements to cardiopulmonary blood flow measurements in discrete regions of interest. The scaling factor linking relative DSA cardiac output measurements to the Fick's absolute measurements was found to be 18.90xCODSA=COFick. Conclusions: This calibrated DSA approach allows repeated simultaneous visualization of vasculature and measurement of blood flow dynamics on a regional level in the living rat.

  14. Intraoperative measurement of graft blood flow--a necessity in liver transplantation.

    Science.gov (United States)

    Rasmussen, A; Hjortrup, A; Kirkegaard, P

    1997-01-01

    Portal venous and hepatic arterial flow was measured intraoperatively in the 70 most recent patients undergoing liver transplantation in our institution. Impaired graft flow due to vascular abnormalities was detected in six patients. One patient suffered from arterial steal due to stenosis of the recipient celiac trunk with blood shunting from the hepatic to the splenic artery. Ligation of the recipient hepatic artery restored the arterial graft flow. In two patients we found reduced portal venous flow due to large portosystemic collaterals. The collaterals accountable for the impaired portal flow were identified and ligated, which restored portal venous graft flow. Excessive sensitivity of the portal venous flow to the position of the graft was found in a 6-month-old boy. Portal venous flow varied considerably, depending upon the position of the graft, and intraoperative flow measurement allowed the best position of the graft to be identified. Two patients developed arterial thrombosis in the early postoperative course. Immediate laparatomy with thrombectomy resulted in good, palpable pulsation in the graft artery in both patients. Intraoperative flow measurement demonstrated satisfactory arterial flow in one patient, whereas there was no net flow in the other patient's graft artery. Pulsation in this patient was caused by blood oscillating in and out of the liver. In conclusion, we find that causes of primary graft dysfunction due to technically flawed reperfusion of the graft can be identified and alleviated by intraoperative measurement of the flow in the graft vessels.

  15. Measurement of cerebral blood flow in the pig by the Xe-133 clearance technique

    International Nuclear Information System (INIS)

    The Xe-133 clearance technique is used to measure cerebral blood flow in the pig, which often serves as an experimental animal for cardiovascular research. The clearance curves are fitted by a two-exponential model. However, the fitted parameters are incompatible with a two-compartmental model: the values found for the parameters depend on the length of the clearance curve analysed. The discrepancies are thought to be consequences of the heterogeneity of cerebral blood flow and of mathematical problems of parameter identification. The non-validity of the relative weight of the fast clearance component as an anatomical or functional parameter is demonstrated. The use of the mean time constant, mean transit time, mean decay constant and initial slope for determination of cerebral blood flow rates is discussed. The mean cerebral blood flow of the anaesthetized pig measured by the clearance technique is found to be lower than the blood flow measured by means of a flow probe around the common carotid artery (with the external carotid artery tied off). The existence of a significant arteriovenous shunt flow is postulated. (orig.)

  16. Factors affecting radioactive microsphere measurement of blood flow in pregnant guinea pigs

    International Nuclear Information System (INIS)

    Comparative blood flow studies were performed in pregnant guinea pigs using radioactive microspheres to test the effects of different sphere sizes on blood flow measurements and the relationship between flows obtained intraoperatively and those performed after 5 days of recovery from anesthesia and surgery. We observed that 1.5% of the cardiac output was shunted through the microcirculation of the carcass, gut, skin and endomyometrium when 15 mu microspheres were used. Intraoperative measurements of heart rate, cardiac output and placental blood flow are significantly lower than measurements made after 5 days recovery. These reductions were ameliorated with the addition of a continuous infusion of isoproterenol and the deletion of atropine from the anesthetic

  17. Micro-particle image velocimetry for velocity profile measurements of micro blood flows.

    Science.gov (United States)

    Pitts, Katie L; Fenech, Marianne

    2013-04-25

    Micro-particle image velocimetry (μPIV) is used to visualize paired images of micro particles seeded in blood flows. The images are cross-correlated to give an accurate velocity profile. A protocol is presented for μPIV measurements of blood flows in microchannels. At the scale of the microcirculation, blood cannot be considered a homogeneous fluid, as it is a suspension of flexible particles suspended in plasma, a Newtonian fluid. Shear rate, maximum velocity, velocity profile shape, and flow rate can be derived from these measurements. Several key parameters such as focal depth, particle concentration, and system compliance, are presented in order to ensure accurate, useful data along with examples and representative results for various hematocrits and flow conditions.

  18. Tomographic cerebral blood flow measurement during carotid surgery

    DEFF Research Database (Denmark)

    Rathenborg, Lisbet Knudsen; Vorstrup, Sidsel; Olsen, K S;

    1994-01-01

    surgery and performing single photon emission computer tomography (SPECT) scanning shortly after the operation thereby pictures rCBF at the time of injection. DESIGN: Ongoing prospective study. SETTINGS: Departments of Vascular Surgery, Neurology and Anaesthesiology, University Hospital, Rigshospitalet......, Copenhagen, Denmark. MATERIAL: 15 patients who during a period of 4 months underwent carotid endarterectomy. CHIEF OUTCOME MEASURES: Prior to surgery rCBF was determined using 133Xe and SPECT. Intraoperatively stump pressure was measured and a bolus of TcHMPAO was injected for later SPECT measurement. MAIN...... carotid surgery. This method may serve as a reference tool in future research on intraoperative cerebral haemodynamics....

  19. Mucosal blood flow measurements using laser Doppler perfusion monitoring

    Institute of Scientific and Technical Information of China (English)

    Dag Arne Lihaug Hoff; Hans Gregersen; Jan Gunnar Hatlebakk

    2009-01-01

    Perfusion of individual tissues is a basic physiological process that is necessary to sustain oxygenation and nutrition at a cellular level. Ischemia, or the insufficiency of perfusion, is a common mechanism for tissue death or degeneration, and at a lower threshold, a mechanism for the generation of sensory signalling including pain. It is of considerable interest to study perfusion of peripheral abdominal tissues in a variety of circumstances. Microvascular disease of the abdominal organs has been implicated in the pathogenesis of a variety of disorders, including peptic ulcer disease, inflammatory bowel disease and chest pain. The basic principle of laser Doppler perfusion monitoring (LDPM) is to analyze changes in the spectrum of light reflected from tissues as a response to a beam of monochromatic laser light emitted. It reflects the total local microcirculatory blood perfusion, including perfusion in capillaries, arterioles, venules and shunts. During the last 20-25 years, numerous studies have been performed in different parts of the gastrointestinal (GI) tract using LDPM. In recent years we have developed a multi-modal catheter device which includes a laser Doppler probe, with the intent primarily to investigate patients suffering from functional chest pain of presumed oesophageal origin. Preliminary studies show the feasibility of incorporating LDPM into such catheters for performing physiological studies in the GI tract. LDPM has emerged as a research and clinical tool in preference to other methods; but, it is important to be aware of its limitations and account for them when reporting results.

  20. Blood flow measurement using a highly filled carbon polymer sandwich sensor and an elasto-pseudo compressible vascular flow.

    Science.gov (United States)

    Mehdian, M; Rahnejat, H

    1996-01-01

    Vascular grafts are widely employed in clinical practice and still pose significant problems of compatibility and longevity, particularly when the prosthesis is to replace arteries of small diameter. Once a graft has been implanted in the vascular tree, there is no easy way of assessing its interactions with the surrounding tissue. Doppler flow probes or some imaging techniques are commonly used to monitor flow velocity in vascular prostheses. It is, however, difficult to monitor a patient's recovery on a continuous basis. Continuous means of measurement can be quite invaluable. This paper presents a high-carbon filled polymer (HCFP) sensor that is developed for blood flow measurement in vascular grafts. Furthermore, a computational fluid dynamics model of incompressible blood flow in elastic blood vessels is presented. PMID:9046189

  1. Blood flow measurements in selected oral tissues in dogs using radiolabelled microspheres and rubidium-86

    International Nuclear Information System (INIS)

    Radiolabelled microspheres and 86Rb were used in dogs to measure oral tissue blood flow. The tissues studied were mandibular alveolar and basal bone, oral mucosa, gingiva, lip, tongue and soft tissue of hard palate. A suspension of 6 x 106 cerium-141 labelled microspheres, 15 + - 5 μm in diameter was injected into the left ventricle through an arterial catheter in 9 healthy adult dogs. Cardiovascular stability was assessed during the catheterization and injection of microspheres. Following the microsphere injection, 500 μCi of 86Rb was injected intravenously and the animal was killed within 60s. Blood flow measured using 86Rb was not significantly different (p > 0.05) from radiolabelled microsphere flow in mandibular basal bone, oral mucosa and gingiva, suggesting that in these oral tissues nutritional or capillary exchange flow is similar to total blood flow. In mandibular alveolar bone, lip, tongue and soft tissue of hard palate, however, 86Rb measurements were significantly greater (p 86Rb shows promise for continued studies of blood flow in healthy and pathological oral tissues. (author)

  2. Measurement of blood flow volume of ocular muscles by Xe-133 clearance method

    International Nuclear Information System (INIS)

    The blood flow volume of the ocular muscles was measured in 8 normal volunteers and 12 cases with miscellaneous opthalmic diseases by Xe-133 clearance method. The average of blood flow volume in the normal subjects was 7.45 ± 2.07 ml/min/100 g, and the blood flow volume ratio of right eye to left eye was 0.94 ± 0.07. The blood flow volume of the ocular muscles was decreased in the cases with stenosis of the internal carotid artery (n = 4, 4.3 ± 2.1 ml/min/100 g), glaucoma (n = 3, 4.7 ± 4.1 ml/min/100 g), arterial scleroses (n = 2, 3.8 ± 0.2 ml/min/100 g) and Takayasu's disease (n = 2, 5.6 ± 0.4 ml/min/100 g), and was increased in the acute inflammatory disease (n = 2, 21.5 ± 2.5 ml/min/100 g). Measurement of the blood flow volume of the ocular muscles using Xe-133 clearance method is useful to evaluate the circulatory abnormality in the ophthalmic diseases. (author)

  3. Measurement of Placental Blood Flow with 133Xe in Normal and Pathological Human Pregnancy

    International Nuclear Information System (INIS)

    Most authors agree that changes in placental circulation play an important part in the genesis of chronic foetal disorders. However, until recently there was no technique by which a quantitative evaluation of placental haemodynamics could be obtained. Our method of measuring placental blood flow represents one application of the use of radioisotopes for measurements of local blood flows. We use 133Xe in solution in physiological serum. This radioactive gas has the advantage of being inert and instantly diffusible. After radiographic or ultrasonic localization of the placenta, 50 μCi of xenon are injected into it transabdominally. A scintillation detector is used to take the 133Xe clearance curve, which is recorded simultaneously on a linear writer and transmitted to a computer. We have made 111 measurements of placental blood flow - 45 in normal pregnancy, 59 in pathological pregnancy and 7 after perfusion of medication. The measurements made it possible to obtain, for the first time, a quantitative evaluation of placental blood flow in women. The value found for normal pregnancies between the thirty-second and the forty-first weeks was 145 ml/100 g per min. The measurements carried out in pathologically pregnant patients (with arterial hypertension, dysgravidity, urinary infection, diabetes, prolonged pregnancy) showed that such pregnancies are accompanied by a statistically significant diminution of placental blood flow, and that the magnitude of this diminution has a bearing on the clinical condition and the state of the child at birth. This method of measurement, which is easily reproducible in the same patient, is accordingly of interest from two points of view. As far as theoretical studies are concerned, it has made possible a quantitative evaluation of placental blood flow and has supplied proof that the maternal disorders which give rise to chronic foetal disorders are usually accompanied by a diminution in placental blood flow. From the practical

  4. Advanced Recording and Preprocessing of Physiological Signals. [data processing equipment for flow measurement of blood flow by ultrasonics

    Science.gov (United States)

    Bentley, P. B.

    1975-01-01

    The measurement of the volume flow-rate of blood in an artery or vein requires both an estimate of the flow velocity and its spatial distribution and the corresponding cross-sectional area. Transcutaneous measurements of these parameters can be performed using ultrasonic techniques that are analogous to the measurement of moving objects by use of a radar. Modern digital data recording and preprocessing methods were applied to the measurement of blood-flow velocity by means of the CW Doppler ultrasonic technique. Only the average flow velocity was measured and no distribution or size information was obtained. Evaluations of current flowmeter design and performance, ultrasonic transducer fabrication methods, and other related items are given. The main thrust was the development of effective data-handling and processing methods by application of modern digital techniques. The evaluation resulted in useful improvements in both the flowmeter instrumentation and the ultrasonic transducers. Effective digital processing algorithms that provided enhanced blood-flow measurement accuracy and sensitivity were developed. Block diagrams illustrative of the equipment setup are included.

  5. Portal blood flow volume measurement in schistosomal patients: evaluation of Doppler ultrasonography reproducibility

    Energy Technology Data Exchange (ETDEWEB)

    Leao, Alberto Ribeiro de Souza; Santos, Jose Eduardo Mourao; Moulin, Danilo Sales; Shigueoka, David Carlos; D' Ippolito, Giuseppe [Universidade Federal de Sao Paulo (UNIFESP/EPM), SP (Brazil). Escola Paulista de Medicina. Dept. de Diagnostico por Imagem]. E-mail: ar.leao@uol.com.br; Colleoni, Ramiro [Universidade Federal de Sao Paulo (UNIFESP/EPM), SP (Brazil). Escola Paulista de Medicina. Dept. de Gastroenterologia

    2008-09-15

    Objective: To evaluate the reproducibility of Doppler ultrasonography in the measurement of portal blood flow volume in schistosomal patients. Materials and methods: Prospective, transversal, observational and self-paired study evaluating 21 patients with hepatosplenic schistosomiasis submitted to Doppler ultrasonography performed by three independent observers for measurement of portal blood flow. Pairwise interobserver agreement was calculated by means of the intraclass correlation coefficient, paired t-test and Pearson's correlation coefficient. Results: Interobserver agreement was excellent. Intraclass correlation ranged from 80.6% to 93.0% (IC at 95% [65.3% ; 95.8%]), with the Pearson's correlation coefficient ranging between 81.6% and 92.7% with no statistically significant interobserver difference regarding the mean portal blood flow volume measured by Doppler ultrasonography (p = 0.954 / 0.758 / 0.749). Conclusion: Doppler ultrasonography has demonstrated to be a reliable method for measuring the portal blood flow volume in patients with portal hypertension secondary to schistosomiasis, with a good interobserver agreement. (author)

  6. CALF BLOOD-FLOW AND POSTURE - DOPPLER ULTRASOUND MEASUREMENTS DURING AND AFTER EXERCISE

    NARCIS (Netherlands)

    VANLEEUWEN, BE; BARENDSEN, GJ; LUBBERS, J; DEPATER, L

    1992-01-01

    To investigate the joint effects of body posture and calf muscle pump, the calf blood flow of eight healthy volunteers was measured with pulsed Doppler equipment during and after 3 min of rhythmic exercise on a calf ergometer in the supine, sitting, and standing postures. Muscle contractions serious

  7. Validation of a continuous penile blood-flow measurement by pulse-volume-plethysmography.

    Science.gov (United States)

    Lavoisier, P; Barbe, R; Gally, M

    2002-04-01

    Today, in the assessment of cavernous artery blood-flow, the most commonly used technique is Doppler ultrasound velocimetry (continuous, pulsed, color-coded or power), which is often considered as the gold standard. Plethysmographic techniques and radioactive tracers have been widely used for the assessment of global penis flow variations but are not adequate for continuous blood-flow measurement. A new pulse-volume plethysmographic (PVP) device using a water-filled penile cuff was employed to assess continuous blood-flow measurement in the penis. Simultaneously Doppler velocity was recorded and served as a gold standard. A penile water-cuff is connected through a pressure tube to a three-way tap. The pulse-volume changes in the penile water-cuff are measured by means of a latex membrane placed over one of the three-way taps. The displacements of the latex are recorded by a photoplethysmograph. The third tap is connected to a 5 l perfusion bag placed 30 cm above the penis so as to maintain constant pressure in the whole device whatever the penis volume. Twenty-four volunteers were tested. The Doppler velocity signal and pulse volume of cavernous arteries were measured simultaneously after PGE1 intra-cavernous injection. Blood-flow variations were induced by increasing penis artery compression with a second penile water-cuff used as a tourniquet fitted onto the penis root, and the pressure of which could be modified by a water-filled syringe. The amplitude of the plethysmographic pulse-volume signal and the area under the Doppler velocity signal were correlated. The inter-patient (n=24) correlation ranged from 0.455 to 0.904, with a mean correlation of 0.704 and P<0.0001. PVP measurement by a water-filled cuff was validated by ultrasound velocimetry. This new continuous, non-invasive and easy-to-use technique enables physiological and physiopathological flow-measurement during sleep, under visual sexual stimulation (VSS), or following artificial erection

  8. Measurement of utero-placental blood flow with /sup 113m/In in diabetic pregnancy

    Energy Technology Data Exchange (ETDEWEB)

    Semmler, K.; Kirsch, G.; Zoellner, P.; Fuhrmann, K.; Jutzi, E. (Zentralinstitut fuer Diabetes, Karlsburg (German Democratic Republic); Ernst-Moritz-Arndt-Universitaet, Greifswald (German Democratic Republic). Radiologische Klinik)

    1985-01-01

    In 122 diabetic pregnancies the placental blood flow has been estimated determining the half-life of the activity inflow (2 MBq /sup 113m/In-transferrin) into the placenta. A highly sensitive detector (modified pinhole collimator) and a computer-supported evaluation were used. 259 flow measurements were compared to the risk of complication in the course of diabetic pregnancy. The half-life values in the diabetic group, calculated by a gamma camera computer system by means of an iterative regression analysis, were significantly different compared to a control group (12 pregnancies without risk.) Severe diabetic angiopathic complications (classes D, F, and R according to White) are accompanied by higher half-life values (placental blood flow reductions) and perinatal complications. Even in pregnant women with gestational diabetes of disturbances of the carbohydrate metabolism disturbed placental hemodynamics is to be found.

  9. Measurement of regional cerebral blood flow by intravenous administation of 133 xenon

    International Nuclear Information System (INIS)

    Reviewing the background and the theory for rCFB measurements the following conditions are established for the use of flow measurement with 133-Xenon as a reliable indicator for indirect measurements of cerebral functional activity. 1. There is a strict coupling between rCBF and regional metabolism. This condition can only be considered to be fulfilled in the normal non-anoxic bran tissue. 2. There is a close correlation between the tissue and the venous concentration of 133-Xenin which can be reliably approximated by the blood-brain partition coefficient. This condition can be considered to be fullfilled in the normal flow range, but not in pathological conditions such as cerebrovascular occlusions. 3. Intercompartment diffusion of 133-Xenon has no significant effect upon the measurement of rCBF values. This condition appear to share its limitations for fulfilement with condition 2. 4. There is no significant contamination by the extracerebral flow components at IH or IV rCBF measurements. 5. There is a negligible 'look through' effect from surrounding areas to region with focal high or low blood flow. (U.W.)

  10. Estimation of intersubject variability of cerebral blood flow measurements using MRI and positron emission tomography

    DEFF Research Database (Denmark)

    Henriksen, Otto Mølby; Larsson, Henrik B W; Hansen, Adam E;

    2012-01-01

    PURPOSE: To investigate the within and between subject variability of quantitative cerebral blood flow (CBF) measurements in normal subjects using various MRI techniques and positron emission tomography (PET). MATERIALS AND METHODS: Repeated CBF measurements were performed in 17 healthy, young...... subjects using three different MRI techniques: arterial spin labeling (ASL), dynamic contrast enhanced T1 weighted perfusion MRI (DCE) and phase contrast mapping (PCM). All MRI measurements were performed within the same session. In 10 of the subjects repeated CBF measurements by (15) O labeled water PET...

  11. Semiquantitative imaging measurement of baseline and vasomodulated normal prostatic blood flow using sildenafil

    OpenAIRE

    Haaga, JR; Exner, A; Fei, B; Seftel, AD

    2006-01-01

    The physiologic variability of blood flow to the prostate has not been studied until this time. We report the vasoactive effects of sildenafil and phenylephrine on blood flow of the normal prostate. Sildenafil increases prostate blood flow by approximately 75% and phenylephrine reduces the flow incrementally. Administration of these drugs with dynamic contrast-enhanced magnetic resonance imaging may improve the diagnosis of cancerous tissue because according to the literature, tumor angiogeni...

  12. On Ultrasonic MTI Measurement of Velocity Profiles in Blood-Flow

    Directory of Open Access Journals (Sweden)

    Bjørn A.J. Angelsen

    1981-04-01

    Full Text Available A theoretical analysis of Doppler frequency estimators proposed to be used in ultrasonic MTI measurements of velocity profiles in blood flow, is given. The estimators give an output in form of a single analogue voltage and the relation of the output to the Doppler spectrum is discussed. Three new estimators are also proposed. All estimators work fairly well for narrow-band Doppler spectra, but errors are found when broad-band spectra are present.

  13. A 133-xenon inhalation system for cerebral blood-flow measurements in ventilated premature babies

    International Nuclear Information System (INIS)

    We constructed a Xenon-133 inhalation and trapping system in order to measure cerebral blood flow of ventilated premature babies by means of the noninvasive 133Xe clearance method. The completely lead-shielded inhalation device is a closed system driven by the baby's own respirator and can thus be safely used at the patients bedside in the intensive care unit. Reproducible proximal airway concentrations of 133Xe (with or without leaks around the endotracheal tube) were obtained by in vitro simulation. (orig.)

  14. Micromachined lab-on-a-tube sensors for simultaneous brain temperature and cerebral blood flow measurements.

    Science.gov (United States)

    Li, Chunyan; Wu, Pei-Ming; Hartings, Jed A; Wu, Zhizhen; Cheyuo, Cletus; Wang, Ping; LeDoux, David; Shutter, Lori A; Ramaswamy, Bharat Ram; Ahn, Chong H; Narayan, Raj K

    2012-08-01

    This work describes the development of a micromachined lab-on-a-tube device for simultaneous measurement of brain temperature and regional cerebral blood flow. The device consists of two micromachined gold resistance temperature detectors with a 4-wire configuration. One is used as a temperature sensor and the other as a flow sensor. The temperature sensor operates with AC excitation current of 500 μA and updates its outputs at a rate of 5 Hz. The flow sensor employs a periodic heating and cooling technique under constant-temperature mode and updates its outputs at a rate of 0.1 Hz. The temperature sensor is also used to compensate for temperature changes during the heating period of the flow sensor to improve the accuracy of flow measurements. To prevent thermal and electronic crosstalk between the sensors, the temperature sensor is located outside the "thermal influence" region of the flow sensor and the sensors are separated into two different layers with a thin-film Copper shield. We evaluated the sensors for accuracy, crosstalk and long-term drift in human blood-stained cerebrospinal fluid. These in vitro experiments showed that simultaneous temperature and flow measurements with a single lab-on-a-tube device are accurate and reliable over the course of 5 days. It has a resolution of 0.013 °C and 0.18 ml/100 g/min; and achieves an accuracy of 0.1 °C and 5 ml/100 g/min for temperature and flow sensors respectively. The prototype device and techniques developed here establish a foundation for a multi-sensor lab-on-a-tube, enabling versatile multimodality monitoring applications.

  15. Two-photon microscopy with double-circle trajectories for in vivo cerebral blood flow measurements

    Science.gov (United States)

    Landolt, Andrin; Obrist, Dominik; Wyss, Matthias; Barrett, Matthew; Langer, Dominik; Jolivet, Renaud; Soltysinski, Tomasz; Roesgen, Thomas; Weber, Bruno

    2013-05-01

    Scanning microscopes normally use trajectories which produce full-frame images of an object at a low frame rate. Time-resolved measurements are possible if scans along a single line are repeated at a high rate. In conjunction with fluorescence labeling techniques, in vivo recording of blood flow in single capillaries is possible. The present work investigates scanning with double-circle trajectories to measure blood flow simultaneously in several vessels of a capillary network. With the trajectory centered near a bifurcation, a double circle crosses each vessel twice, creating a sensing gate for passing dark red blood cells in fluorescently labeled plasma. From the stack of scans repeated at 1,300 Hz, the time-resolved velocity is retrieved using an image correlation approach. Single bifurcation events can be identified from a few fluorescently labeled red blood cells. The applicability of the method for in vivo measurements is illustrated on the basis of two-photon laser scanning microscopy of the cerebral capillary network of mice. Its performance is assessed with synthetic data generated from a two-phase model for the perfusion in a capillary network. The calculation of velocities is found to be sufficiently robust for a wide range of conditions. The achievable limits depend significantly on the experimental conditions and are estimated to be in the 1 μm/s (velocity) and 0.1 s (time resolution) ranges, respectively. Some manual fine-tuning is required for optimal performance in terms of accuracy and time resolution. Further work may lead to improved reliability with which bifurcation events are identified in the algorithm and to include red blood cell flux and hematocrit measurements. With the capability for time-resolved measurements in all vessels of a bifurcation, double-circle scanning trajectories allow a detailed study of the dynamics in vascular networks.

  16. Evaluation of MR angiography and blood flow measurement in abdominal and peripheral arterial occlusive disease

    Energy Technology Data Exchange (ETDEWEB)

    Tabuchi, Kenji [Dokkyo Univ. School of Medicine, Mibu, Tochigi (Japan)

    2000-03-01

    To assess the characteristics of blood flow measurement with MR Angiography (MRA) to evaluate the status of vascular stenoses, two or three dimensional time-of-flight MRA and velocity-encoded cine MR were performed in the 230 segments of 35 patients, with abdominal and peripheral arterial occlusive diseases. In 11 of these 35 patients digital subtraction angiography was additionally underwent, and the stenotic findings was compared with MRA. There were 17 segments in which the velocity could not be measured, because the blood flow exceeded the upper limit of peak-encoded velocity (VENC) which was set at 120 cm/sec. Therefore, it is necessary to set the upper limit of VENC at higher than 120 cm/sec. There were 11 stenotic findings in DSA and 20 stenotic findings in MRA. Pulsatility Index (PI=(max velocity-min. velocity)/average velocity) were used for evaluating the blood flow waveform, and there were significant difference between the 11 stenotic findings of DSA and the others'. In summery, MRA was considered as useful examination to assess the degree of the vascular stenoses in abdominal and peripheral arterial occlusive disease. (author)

  17. Absolute cerebral blood flow and blood volume measured by magnetic resonance imaging bolus tracking: comparison with positron emission tomography values

    DEFF Research Database (Denmark)

    Østergaard, Leif; Smith, D F; Vestergaard-Poulsen, Peter;

    1998-01-01

    The authors determined cerebral blood flow (CBF) with magnetic resonance imaging (MRI) of contrast agent bolus passage and compared the results with those obtained by O-15 labeled water (H215O) and positron emission tomography (PET). Six pigs were examined by MRI and PET under normo......- and hypercapnic conditions. After dose normalization and introduction of an empirical constant phi Gd, absolute regional CBF was calculated from MRI. The spatial resolution and the signal-to-noise ratio of CBF measurements by MRI were better than by the H215O-PET protocol. Magnetic resonance imaging cerebral...... blood volume (CBV) estimates obtained using this normalization constant correlated well with values obtained by O-15 labeled carbonmonooxide (C15O) PET. However, PET CBV values were approximately 2.5 times larger than absolute MRI CBV values, supporting the hypothesized sensitivity of MRI to small...

  18. In Vivo μPIV Measurements of Blood Flow in Small Vessels of a Rat Model.

    Science.gov (United States)

    Wei, Timothy; Conner, Nadine; Russell, John; Legac, Paul

    2007-11-01

    Ongoing research at the University of Wisconsin Medical School is addressing the effects of perfusion of glottal tissue on voice production. Building on the approach developed by Gharib's group at CalTech for embryonic zebra fish, we have modified μPIV to measure flow in capillaries and small blood vessels in a live rat model. In lieu of seeding particles, the DPIV correlation algorithm tracks the motion of red blood cells moving through these vessels. The methodology will be presented along with a video sequence showing measurements made from muscle tissue laid nominally flat on a microscope stage. Challenges of measurements in three-dimensional geometries, i.e. the throat, will be discussed.

  19. A study on regional cerebral blood flow measurement by 133FXe inhalation method

    International Nuclear Information System (INIS)

    Fundamental and clinical investigations were performed on reliability of Fourier analysis of head clearance curves in regional cerebral blood flow measurement by 133Xe inhalation methods as compared with conventional Obrist analysis. Fourier analysis revealed better reproducibilities determined by computer simulated curves and repetitive measurements in man than Obrist analysis. In the studies of the changes of regional cerebral blood flow from the resting conditions to the conditions of finger movement, listening to verbal material or music and reading aloud in right-handed normal subjects, both F1 (a flow of the fast component of two compartmental model) and ISI (Initial Slope Index: calculated from the initial slope of the wash out curves corrected for recirculation) of Fourier analysis were more sensitive to detect significant changes than Obrist analysis. On the basis of the fact mentioned above, it was concluded that ISI of Fourier analysis was the best index of regional cerebral blood flow. Age-matched normal values of ISI of Fourier analysis were calculated from 132 measurements in 105 normal right-handed subjects, aged 19 to 80 years old (mean 42 years). Mean brain ISI showed significant negative correlation with advancing age (r = -0.70, p < 0.001). The regression line and 95% confidence interval were Y = -0.32X + 69.6 and +- 11.2, respectively. In comparison with the measured values of the patients with cerebrovascular disorders, this age-matched normal values were proved to be sufficient for practical use. Regional ISI also showed significant negative correlations with advancing age in the entire brain (p < 0.001). The regional reduction of ISI with advancing age was significantly greater in the regional distribution of the middle cerebral arteries bilaterally, compared with regions in the distributions of either the anterior cerebral, the posterior cerebral or vertebrobasilar arteries (p < 0.05). (J.P.N.)

  20. Simplifying the xenon-enhanced CT technique for measuring cerebral blood flow

    International Nuclear Information System (INIS)

    The authors present their study to simplify the xenon-enhanced CT technique for measuring cerebral blood flow (CBF) by monitoring the end-tidal expired-air xenon concentration (CXe) with use of CT scanning. Measurement of CBF with xenon CT requires that CXe be monitored as a function of time, and with conventional methods, specialized equipment (eg, thermoconductivity meters) is employed. In the proposed technique, CXe is monitored by scanning the patient's expired air concurrent with the brain tissue. A flexible breathing tube is used to channel the expired air through the scan field to enable sampling

  1. Renal blood flow and metabolism after cold ischaemia: peroperative measurements in patients with calculi

    DEFF Research Database (Denmark)

    Petersen, H K; Henriksen, Jens Henrik Sahl

    1984-01-01

    Peroperative measurements of renal blood flow (RBF), renal O2-uptake, and renal venous lactate/pyruvate (L/P) ratio were performed before and after a period of 30-71 min of hypothermic (10-15 degrees C) renal ischaemia in nine patients, undergoing surgery for renal calculi. Before ischaemia, RBF.......01) immediately after re-established perfusion and 36% (P less than 0.02) 30 min later. In one additional patient, who had a short warm ischaemia (8 min), the flow pattern was the same. As arterial pressure remained constant, the reduced RBF signifies an increased renal vascular resistance. Renal O2-uptake...... and renal venous L/P ratio were almost constant, indicating no significant anaerobic processes being involved in the flow response. None of the patients showed any signs of reactive hyperaemia. It is concluded that hypothermic renal ischaemia may be followed by an increased renal vascular resistance even...

  2. Test-Retest Repeatability of Myocardial Blood Flow Measurements using Rubidium-82 Positron Emission Tomography

    Science.gov (United States)

    Efseaff, Matthew

    Rubidium-82 positron emission tomography (PET) imaging has been proposed for routine myocardial blood flow (MBF) quantification. Few studies have investigated the test-retest repeatability of this method. Same-day repeatability of rest MBF imaging was optimized with a highly automated analysis program using image-derived input functions and a dual spillover correction (SOC). The effects of heterogeneous tracer infusion profiles and subject hemodynamics on test-retest repeatability were investigated at rest and during hyperemic stress. Factors affecting rest MBF repeatability included gender, suspected coronary artery disease, and dual SOC (p stress, and 0.95 for stress / rest myocardial flow reserve (MFR). Subjects with heterogeneous tracer infusion profiles and hemodynamic conditions had significantly less repeatable MBF measurements at rest, stress, and stress/rest flow reserve (p < 0.05).

  3. Visualization and measurement of capillary-driven blood flow using spectral domain optical coherence tomography

    OpenAIRE

    Cito, Salvatore; Ahn, Yeh-Chan; Pallares, Jordi; Duarte, Rodrigo Martinez; Chen, Zhongping; Madou, Marc; Katakis, Ioanis

    2012-01-01

    Capillary-driven flow (CD-flow) in microchannels plays an important role in many microfluidic devices. These devices, the most popular being those based in lateral flow, are becoming increasingly used in health care and diagnostic applications. CD-flow can passively pump biological fluids as blood, serum or plasma, in microchannels and it can enhance the wall mass transfer by exploiting the convective effects of the flow behind the meniscus. The flow behind the meniscus has not been experimen...

  4. Simultaneous measurement of blood flow and glucose metabolism by autoradiographic techniques

    International Nuclear Information System (INIS)

    A double tracer autoradiographic technique using 131I-iodo-antipyrine and 14C-deoxyglucose is presented for the simultaneous measurement of blood flow and cerebral glucose utilization in the same animal. 131I is a gamma emitting isotope with a half life of 8.06 days and can be detected with adequate resolution on standard autoradiographic films. Autoradiograms are made before and after decay of 131I; the time interval between the 2 exposures and the concentration of the 2 tracers is adjusted to avoid significant cross-contamination. In this way, 2 film exposures are obtained which can be processed quantitatively like single tracer autoradiograms. The validity of the method for the investigation of local coupling of flow and metabolism was tested under various physiological and pathophysiological conditions. Coupling was tight in barbiturate-anesthetized healthy animals, but not under halothane anesthesia where uncoupling occurred in various subcortical structures. Focal seizures induced by topical application of penicillin on the cortical surface led to a coupled increase of metabolism and flow in thalamic relay nuclei but not at the site of penicillin administration where increased glucose utilization was not accompanied by similar increase in blood flow. Both coupled and uncoupled increases in local glucose utilization were observed in spreading depression and in circumscribed areas of experimental brain tumors. The results obtained demonstrate that double tracer autoradiography allows allows the very precise local assessment of cerebral blood flow and glucose utilization, and, therefore, is particularly suited to the study of regional coupling processes under various experimental conditions

  5. Quantitative measurement of cerebral blood flow on patients with early syphilis

    Institute of Scientific and Technical Information of China (English)

    ZHONG Ji-Jun; WU Jin-Chang; YANG Yi; TANG Jun; LIU Zeng-Li; SHI Xin

    2005-01-01

    To study quantitative change of cerebral blood flow (CBF) on patients with early syphilis, we have established a method on absolute measurement of rCBF by using SPECT with Ethyl Cysteinate Dimmer (ECD) as imaging agent, and the method was applied to measure rCBF on patients with early syphilis. The rCBF values measured by this method are highly consistent with the values measured by other classical methods such as SPECT (123I-IMP) and PET (15O-H2O). The rCBF values for early syphilis patients and the normal control show some statistical differences.A routine quantitative absolute measurement of rCBF featured with simple procedures is therefore on the way of maturation.

  6. Cerebral blood flow and intracranial pulsatility studied with MRI: measurement, physiological and pathophysiological aspects

    Energy Technology Data Exchange (ETDEWEB)

    Waahlin, Anders

    2012-07-01

    During each cardiac cycle pulsatile arterial blood inflates the vascular bed of the brain, forcing cerebrospinal fluid (CSF) and venous blood out of the cranium. Excessive arterial pulsatility may be part of a harmful mechanism causing cognitive decline among elderly. Additionally, restricted venous flow from the brain is suggested as the cause of multiple sclerosis. Addressing hypotheses derived from these observations requires accurate and reliable investigational methods. This work focused on assessing the pulsatile waveform of cerebral arterial, venous and CSF flows. The overall aim of this dissertation was to explore cerebral blood flow and intracranial pulsatility using MRI, with respect to measurement, physiological and pathophysiological aspects.Two-dimensional phase contrast magnetic resonance imaging (2D PCMRI) was used to assess the pulsatile waveforms of cerebral arterial, venous and CSF flow. The repeatability was assessed in healthy young subjects. The 2D PCMRI measurements of cerebral arterial, venous and CSF pulsatility were generally repeatable but the pulsatility decreased systematically during the investigation. A method combining 2D PCMRI measurements with invasive CSF infusion tests to determine the magnitude and distribution of compliance within the craniospinal system was developed and applied in a group of healthy elderly. The intracranial space contained approximately two thirds of the total craniospinal compliance. The magnitude of craniospinal compliance was less than suggested in previous studies. The vascular hypothesis for multiple sclerosis was tested. Venous drainage in the internal jugular veins was compared between healthy controls and multiple sclerosis patients using 2D PCMRI. For both groups, a great variability in the internal jugular flow was observed but no pattern specific to multiple sclerosis could be found. Relationships between regional brain volumes and potential biomarkers of intracranial cardiac-related pulsatile

  7. Evaluation of a new high power, wide separation laser Doppler probe : Potential measurement of deeper tissue blood flow

    NARCIS (Netherlands)

    Clough, Geraldine; Chipperfield, Andrew; Byrne, Christopher; de Mul, Frits; Gush, Rodney

    2009-01-01

    Objective: To compare the output from a novel high power, wide separation laser Doppler flow probe (DP1-V2-HP, 4 mm, with IRLD20) with that of a standard flow probe (DP1-V2, 0.5 mm, with DRT4) (Moor UK) and to explore its potential for use in the noninvasive measurement of blood flow in deeper tissu

  8. Gingival blood flow under total combs by functional pressure evaluated with laser-Doppler flowmetry, a non-invasive method of blood flow measurement

    International Nuclear Information System (INIS)

    Gingival blood flow under total-combs by functional pressure evaluated with Laser-Doppler Flowmetry, a non-invasive method of blood flow measurement. Microcirculation of gum's capillary system can be measured non-invasive by Laser-Doppler-Flowmetry (LDF). Circulation, defined by the number of floating erythrocytes per unit of time, is measured by a fibro-optical Laser-Doppler-Flowmetry. The task was to examine, if there is any change of gum's circulation during strain and relief. Circulation on defined measurepoints, divided on the four quadrants, was determined among maximal strain and subsequent relief, on one probationer (complete denture bearer). Before every measure session systemic pressure was taken. LDF-value was taken on top of jaw-comb, in doing so, to get reproducible result and a satisfying fixation of the probe, there was made an artificial limb of the upper and lower comb. In the upper comb a dynamometer-box, which determined minimal and maximal comb pressure, was integrated. The received results of the LDF-measurement, expressed as perfusion units (PU) were lower under applied pressure than by pressure points more distant. Hyperemia, resulting during relief, seemed the more intense, the less perfusion was before. This new, non-invasive kind of circulation measurement seems to be quite predestined to be used for gingival diagnostic under artificial limb in the future. (author)

  9. Quantitative measurement of blood flow dynamics in chorioallantoic membrane of chicken embryo using laser Doppler anemometry

    Science.gov (United States)

    Borozdova, M. A.; Stiukhina, E. S.; Sdobnov, A. A.; Fedosov, I. V.; Postnov, D. E.; Tuchin, V. V.

    2016-04-01

    We report the results on in ovo application of developed Laser Doppler Anemometer (LDA) device. The chorioallantoic membrane (CAM) of 9-13 days chicken embryos was used as a biological model that allows an easy access to both arterial and venous vessels of different size. The key point of our study was to find out how the periodic and aperiodic pulsations of blood flow (which are inevitable in living organism) will affect the LDA functions and measuring capability. Specifically, we (i) developed the technique to extract and refine the pulse rhythm from the signal received from a vessel, and (ii) analyzed the changes in power spectra of LDA signal that are caused by heart beating and considerably complicate the reliable measurement of Doppler shift. Our main conclusion is that the algorithm of LDA data processing need to be improved, and this possibly can be done by counting the information on current phase of cardiac cycle.

  10. Quantitative measurements of cerebral blood flow in volume imaging PET scanners

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R.J.; Shao, L.; Freifelder, R.; Karp, J.S.; Ragland, J.D. [Univ. of Pennsylvania, Philadelphia, PA (United States)

    1995-08-01

    Quantitative measurements of Cerebral Blood Flow (CBF) are performed in a volume imaging PET Scanner by means of moderate activity infusions. In equilibrium infusions, activations are measured by scanning over 10 minutes with 16 minute activations. Typical measured whole brain CBF values are 37{+-}8 ml/min/100g, close to the value of 42 ml/min/100g reported by other groups using this method. For ramped infusions, scanning over 4 minutes with 5 minute activations results in whole brain CBFs of 49 {+-} 9 ml/min/100g, close to the Kety and Schmidt value of 50 ml/min/100g. Both equilibrium and ramped infusion methods have been used to study face and word memory in human subjects. Both methods were able to detect significant activations in regions implicated in human memory. The authors conclude that precise quantitation of regional CBF is achieved using both methods, and that ramped infusions also provide accurate measures of CBF. In addition a simplified protocol for ramped infusion studies has been developed. In this method the whole brain tissue time activity curve generated from dynamic scanning is replaced by an appropriately scaled camera coincidence countrate curve. The resulting whole brain CBF values are only 7% different from the dynamic scan and fit results. Regional CBFs (rCBF) may then be generated from the summed image (4.25 minutes) using a count density vs flow lookup table.

  11. A new sensor for stress measurement based on blood flow fluctuations

    Science.gov (United States)

    Fine, I.; Kaminsky, A. V.; Shenkman, L.

    2016-03-01

    It is widely recognized that effective stress management could have a dramatic impact on health care and preventive medicine. In order to meet this need, efficient and seamless sensing and analytic tools for the non-invasive stress monitoring during daily life are required. The existing sensors still do not meet the needs in terms of specificity and robustness. We utilized a miniaturized dynamic light scattering sensor (mDLS) which is specially adjusted to measure skin blood flow fluctuations and provides multi- parametric capabilities. Based on the measured dynamic light scattering signal from the red blood cells flowing in skin, a new concept of hemodynamic indexes (HI) and oscillatory hemodynamic indexes (OHI) have been developed. This approach was utilized for stress level assessment for a few usecase scenario. The new stress index was generated through the HI and OHI parameters. In order to validate this new non-invasive stress index, a group of 19 healthy volunteers was studied by measuring the mDLS sensor located on the wrist. Mental stress was induced by using the cognitive dissonance test of Stroop. We found that OHIs indexes have high sensitivity to the mental stress response for most of the tested subjects. In addition, we examined the capability of using this new stress index for the individual monitoring of the diurnal stress level. We found that the new stress index exhibits similar trends as reported for to the well-known diurnal behavior of cortisol levels. Finally, we demonstrated that this new marker provides good sensitivity and specificity to the stress response to sound and musical emotional arousal.

  12. [Coronary artery blood flow velocity non-invasively measured using a vessel-tracking pulsed Doppler system].

    Science.gov (United States)

    Tateishi, O; Aizawa, O; Okamura, T; Yoshida, T; Furuhata, H; Seo, Y; Iinuma, K; Shiki, E

    1988-09-01

    A newly-developed noninvasive method was used to measure left coronary blood flow during phantom experiments. Two techniques were used in which: (1) the sample position can always be set in a fluctuating vessel using a wall echo-tracking method with a phase-locked-loop, and (2) the Doppler reference signal was generated separately synchronous with the wall echo signal. These techniques were combined, using a commercially available pulsed Doppler apparatus (SSH-40B: Toshiba). Basic experiments were performed using a blood vessel phantom to verify the validity of these systems. Blood flow velocity in the fluctuating tube could be measured clearly using a vessel-tracking method. The blood flow velocity of the left anterior descending artery was measured in three normal subjects and in seven patients from the third intercostal space along the left sternal border. The velocity pattern was characterized by a crescendo-decrescendo shape in diastole. The peak velocity which appeared in diastole ranged from 19 to 69 cm/sec, with no difference by disease entity. However, in all cases, the blood flow velocity signals were marred by extraneous signals, making it impossible to measure blood flow velocity during systole. Further improvement of the system is mandatory in order to use this flowmeter clinically.

  13. Regional cerebral blood flow measurement by N-isopropyl-p-[123I] iodoamphetamine

    International Nuclear Information System (INIS)

    Eight patients with hemiplegia in chronic stages were studied with N-isopropyl-p-[123I] iodoamphetamine (IMP) and single-photon emission computed tomography (SPECT) comparing with X-ray CT findings. In three patients, focal decreases of IMP were observed and these areas were larger than the abnormal areas found by X-ray CT. In the other five patients, hemispherical low perfusion of IMP was observed by SPECT, but X-ray CT showed severe atrophy with normal density. In two patients, cerebral angiography showed no abnormalities in the arterial phase. Regional cerebral blood flow measurement using IMP would be of great value in evaluating abnormal cerebral functions in the chronic state of acute infantile hemiplegia and cerebral palsy. (author)

  14. Optimal velocity encoding during measurement of cerebral blood flow volume using phase-contrast magnetic resonance angiography

    Institute of Scientific and Technical Information of China (English)

    Gang Guo; Yonggui Yang; Weiqun Yang

    2011-01-01

    This study investigated the effect of velocity encoding on measurement of brain blood flow and blood volume of inflow and outflow using phase-contrast magnetic resonance angiography. A single two-dimensional phase-contrast magnetic resonance angiography slice was applied perpendicular to the internal carotid artery and the vertebral artery at C2 level. For each subject, the velocity encoding was set from 30 to 90 cm/s with an interval of 10 cm/s for a total of seven settings. Various velocity encodings greatly affected blood flow volume, maximal blood flow velocity and mean blood flow velocity in the internal carotid artery, but did not significantly affect vertebral arteries and jugular veins. When velocity encoding was 60-80 cm/s, the inflow blood volume was 655 ± 118 mL/min, and the outflow volume was 506 ± 186 mL/min. The ratio of outflow/inflow was steady at 0.78-0.83, and there was no aliasing in any of the images. These findings suggest that velocity encodings of 60-80 cm/s should be selected during measurement of cerebral blood flow volume using phase-contrast magnetic resonance angiography.

  15. 21 CFR 870.2120 - Extravascular blood flow probe.

    Science.gov (United States)

    2010-04-01

    ... blood flow probe. (a) Identification. An extravascular blood flow probe is an extravascular ultrasonic or electromagnetic probe used in conjunction with a blood flowmeter to measure blood flow in...

  16. Full-field high-speed laser Doppler imaging system for blood-flow measurements

    Science.gov (United States)

    Serov, Alexandre; Lasser, Theo

    2006-02-01

    We describe the design and performance of a new full-field high-speed laser Doppler imaging system developed for mapping and monitoring of blood flow in biological tissue. The total imaging time for 256x256 pixels region of interest is 1.2 seconds. An integrating CMOS image sensor is utilized to detect Doppler signal in a plurality of points simultaneously on the sample illuminated by a divergent laser beam of a uniform intensity profile. The integrating property of the detector improves the signal-to-noise ratio of the measurement, which results in high-quality flow-images provided by the system. The new technique is real-time, non-invasive and the instrument is easy to use. The wide range of applications is one of the major challenges for a future application of the imager. High-resolution high-speed laser Doppler perfusion imaging is a promising optical technique for diagnostic and assessing the treatment effect of the diseases such as e.g. atherosclerosis, psoriasis, diabetes, skin cancer, allergies, peripheral vascular diseases, skin irritancy and wound healing. We present some biological applications of the new imager and discuss the perspectives for the future implementations of the imager for clinical and physiological applications.

  17. Perfusion MRI (dynamic susceptibility contrast imaging) with different measurement approaches for the evaluation of blood flow and blood volume in human gliomas

    DEFF Research Database (Denmark)

    Thomsen, Henrik; Larsson, Elna-Marie; Steffensen, Elena

    2012-01-01

    technique arterial spin labelling (ASL) presently provides measurement only of cerebral blood flow (CBF), which has not been widely used in human brain tumor studies. Purpose: To assess if measurement of blood flow is comparable with measurement of blood volume in human biopsy-proven gliomas obtained by DSC......, and glioblastomas. Results: rCBF and rCBV measurements obtained with the maximum perfusion method were correlated when normalized to white matter (r ¼ 0.60) and to the cerebellum (r ¼ 0.49). Histogram analyses of rCBF and rCBV showed that mean and median values as well as skewness and peak position were correlated......-MRI using two different regions for normalization and two different measurement approaches. Material and Methods: Retrospective study of 61 patients with different types of gliomas examined with DSC perfusion MRI. Regions of interest (ROIs) were placed in tumor portions with maximum perfusion on rCBF and r...

  18. Hyperhomocysteinemia decreases bone blood flow

    Directory of Open Access Journals (Sweden)

    Neetu T

    2011-01-01

    Full Text Available Neetu Tyagi*, Thomas P Vacek*, John T Fleming, Jonathan C Vacek, Suresh C TyagiDepartment of Physiology and Biophysics, School of Medicine, University of Louisville, Louisville, KY, USA *These authors have equal authorshipAbstract: Elevated plasma levels of homocysteine (Hcy, known as hyperhomocysteinemia (HHcy, are associated with osteoporosis. A decrease in bone blood flow is a potential cause of compromised bone mechanical properties. Therefore, we hypothesized that HHcy decreases bone blood flow and biomechanical properties. To test this hypothesis, male Sprague–Dawley rats were treated with Hcy (0.67 g/L in drinking water for 8 weeks. Age-matched rats served as controls. At the end of the treatment period, the rats were anesthetized. Blood samples were collected from experimental or control rats. Biochemical turnover markers (body weight, Hcy, vitamin B12, and folate were measured. Systolic blood pressure was measured from the right carotid artery. Tibia blood flow was measured by laser Doppler flow probe. The results indicated that Hcy levels were significantly higher in the Hcy-treated group than in control rats, whereas vitamin B12 levels were lower in the Hcy-treated group compared with control rats. There was no significant difference in folate concentration and blood pressure in Hcy-treated versus control rats. The tibial blood flow index of the control group was significantly higher (0.78 ± 0.09 flow unit compared with the Hcy-treated group (0.51 ± 0.09. The tibial mass was 1.1 ± 0.1 g in the control group and 0.9 ± 0.1 in the Hcy-treated group. The tibia bone density was unchanged in Hcy-treated rats. These results suggest that Hcy causes a reduction in bone blood flow, which contributes to compromised bone biomechanical properties.Keywords: homocysteine, tibia, bone density

  19. Laser Doppler flowmetry is valid for measurement of cerebral blood flow autoregulation lower limit in rats

    DEFF Research Database (Denmark)

    Tonnesen, Jan; Pryds, Anders; Larsen, Erik Hviid;

    2005-01-01

    was challenged by controlled systemic haemorrhage, or (2) cerebral blood flow was varied by manipulating the arterial partial pressure of CO2 (Pa,CO2). LDF slightly overestimated CBF under conditions of haemorrhagic shock and haemodilution caused by controlled haemorrhage (paired t test, P

  20. Unilateral kidney blood flow measurement using the 81Rb/81mKr ratio.

    NARCIS (Netherlands)

    van Herk, G.; de Zeeuw, D.

    1978-01-01

    A new method has been developed for the continuous quantification of kidney blood flow, utilizing the unique physical and biological properties of the radioactive tracer couple: rubidium-81/krypton-81m. After intravenous injection, 81Rb concentrates primarily in the kidneys, where it continuously ge

  1. PET measured evoked cerebral blood flow responses in an awake monkey

    International Nuclear Information System (INIS)

    We have developed a method to measure task-related regional cerebral blood flow (BF) responses in an awake, trained monkey using positron emission tomography (PET) and H215O. We trained an animal with operant conditioning using only positive reinforcement to climb unassisted into a modified primate chair that was then positioned in the PET scanner. A special headholder and acrylic skull cap permitted precise placement and accurate repositioning. We measured BF qualitatively with bolus injection of H215O and 40-s scan. Each session included scans at rest interposed with scans during vibration of a forepaw. Regional responses were identified using subtraction image analysis. After global normalization, a resting image was subtracted on a pixel-by-pixel basis from a comparable image collected during vibration. The region of peak response occurred in contralateral sensorimotor cortex with a mean magnitude of 11.6% (+/- 3.2%) of the global mean value for 10 separate experiments, significantly greater than the mean qualitative BF change (0.4 +/- 3.6%; p less than 0.00001) in the same region for seven rest-rest pairs. This newly developed technique forms the basis for a wide variety of experiments

  2. Blood pressure measurement

    Science.gov (United States)

    Diastolic blood pressure; Systolic blood pressure; Blood pressure reading; Measuring blood pressure ... or your health care provider will wrap the blood pressure cuff snugly around your upper arm. The ...

  3. A comparison of two methods to measure coronary flow reserve in the setting of coronary angioplasty: intracoronary blood flow velocity measurements with a Doppler catheter, and digital subtraction cineangiography

    NARCIS (Netherlands)

    P.W.J.C. Serruys (Patrick); F. Zijlstra (Felix); G-J. Laarman (GertJan); J.H.C. Reiber (Johan); K.J. Beatt (Kevin); J.R.T.C. Roelandt (Jos)

    1989-01-01

    textabstractIntracoronary blood flow velocity measurements with a Doppler balloon catheter and the radiographic assessment of myocardial perfusion with contrast media, before and after the intracoronary administration of papaverine, have previously been used to investigate regional coronary flow res

  4. High quality optical microangiography of ocular microcirculation and measurement of total retinal blood flow in mouse eye

    Science.gov (United States)

    Zhi, Zhongwei; Yin, Xin; Dziennis, Suzan; Alpers, Charles E.; Wang, Ruikang K.

    2013-03-01

    Visualization and measurement of retinal blood flow (RBF) is important to the diagnosis and management of different eye diseases, including diabetic retinopathy. Optical microangiography (OMAG) is developed for generating 3D dynamic microcirculation image and later refined into ultra-high sensitive OMAG (UHS-OMAG) for true capillary vessels imaging. Here, we present the application of OMAG imaging technique for visualization of depth-resolved vascular network within retina and choroid as well as measurement of total retinal blood flow in mice. A fast speed spectral domain OCT imaging system at 820nm with a line scan rate of 140 kHz was developed to image mouse posterior eye. By applying UHS-OMAG scanning protocol and processing algorithm, we achieved true capillary level imaging of retina and choroid vasculature in mouse eye. The vascular pattern within different retinal layers and choroid was presented. An en face Doppler OCT approach [1] without knowing Doppler angle was adopted for the measurement of total retinal blood flow. The axial blood flow velocity is measured in an en face plane by raster scanning and the flow is calculated by integrating over the vessel area of the central retinal artery.

  5. Design and implementation of a smartphone-based portable ultrasound pulsed-wave Doppler device for blood flow measurement.

    Science.gov (United States)

    Huang, Chih-Chung; Lee, Po-Yang; Chen, Pay-Yu; Liu, Ting-Yu

    2012-01-01

    Blood flow measurement using Doppler ultrasound has become a useful tool for diagnosing cardiovascular diseases and as a physiological monitor. Recently, pocket-sized ultrasound scanners have been introduced for portable diagnosis. The present paper reports the implementation of a portable ultrasound pulsed-wave (PW) Doppler flowmeter using a smartphone. A 10-MHz ultrasonic surface transducer was designed for the dynamic monitoring of blood flow velocity. The directional baseband Doppler shift signals were obtained using a portable analog circuit system. After hardware processing, the Doppler signals were fed directly to a smartphone for Doppler spectrogram analysis and display in real time. To the best of our knowledge, this is the first report of the use of this system for medical ultrasound Doppler signal processing. A Couette flow phantom, consisting of two parallel disks with a 2-mm gap, was used to evaluate and calibrate the device. Doppler spectrograms of porcine blood flow were measured using this stand-alone portable device under the pulsatile condition. Subsequently, in vivo portable system verification was performed by measuring the arterial blood flow of a rat and comparing the results with the measurement from a commercial ultrasound duplex scanner. All of the results demonstrated the potential for using a smartphone as a novel embedded system for portable medical ultrasound applications. PMID:22293750

  6. Advances in regional cerebral blood flow measurement and patho-physiological analysis by SPECT

    International Nuclear Information System (INIS)

    Recently, two kinds of radiopharmaceuticals have been developed to represent the biodistribution of regional blood flow, which are N-isopropyl-p-[123I]iodoamphetamine (IMP) and 99mTc-hexamethylpropylene-amine-oxime (HMPAO). In this paper, I mentioned the charachteristics, clinical usage and imitation of these two radiolabeled agents. The advantage of 123I-IMP is that it has high first-pass extraction and long retention in brain tissue, hence it can be used to measure the absolute values of regional cerebral blood flow (rCBF). When the kinetics of 123I-IMP is assumed to be freely diffusible in the brain, its behavior is considered by 2-compartment model, especially which is assumed by the microsphere model in the early period after the i.v. injection of 123I-IMP. Comparing the rCBF measured by 123I-IMP with that by 133Xe inhalation SPECT method, we have to consider PaCO2 when both SPECT studies are performed, because PaCO2 is one of the big factors which make effects on the alteration of rCBF. 123I-IMP has an interesting character of the redistribution phenomenon which represrent the degree of ischemia in the cerebrovascular diseases. Distribution volume is one of the important information obtained by the SPECT study with 123I-IMP, which represent the degree of retention, i.e. binding potential of 123I-IMP in the brain tissue. I introduced the usage of the distribution volume of 123I-IMP, which was constructed in the rate constant square method, in the differential diagnosis of Parkinson's disease and progressive supranuclear palsy (PSP). The clinical usage of 99m Tc-HMPAT was mentioned, the advantage of which is the rapid fixation in the brain tissue and the distribution does not change for long time after the i.v. injection. Hence 99mTc-HMPAO is used for the diagnosis of epileptic foci and certain loading tests such as balloon occlusion test, postural test and acetazolamide loading test. (author)

  7. Advances in regional cerebral blood flow measurement and patho-physiological analysis by SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Odano, Ikuo (Niigata Univ. (Japan). School of Medicine)

    1994-04-01

    Recently, two kinds of radiopharmaceuticals have been developed to represent the biodistribution of regional blood flow, which are N-isopropyl-p-[[sup 123]I]iodoamphetamine (IMP) and [sup 99m]Tc-hexamethylpropylene-amine-oxime (HMPAO). The charachteristics, clinical usage and imitation of these two radiolabeled agents are discussed. The advantage of [sup 123]I-IMP is that it has high first-pass extraction and long retention in brain tissue, hence it can be used to measure the absolute values of regional cerebral blood flow (rCBF). When the kinetics of [sup 123]I-IMP is assumed to be freely diffusible in the brain, its behavior is considered by 2-compartment model, especially which is assumed by the microsphere model in the early period after the i.v. injection of [sup 123]I-IMP. Comparing the rCBF measured by [sup 123]I-IMP with that by [sup 133]Xe inhalation SPECT method, we have to consider PaCO[sub 2] when both SPECT studies are performed, because PaCO[sub 2] is one of the big factors which make effects on the alteration of rCBF. [sup 123]I-IMP has an interesting character of the redistribution phenomenon which represrent the degree of ischemia in the cerebrovascular diseases. Distribution volume an important datum obtained by the SPECT study with [sup 123]I-IMP, which represent the degree of retention, i.e. binding potential of [sup 123]I-IMP in the brain tissue. I introduced the usage of the distribution volume of [sup 123]I-IMP, which was constructed in the rate constant square method, in the differential diagnosis of Parkinson's disease and progressive supranuclear palsy (PSP). The clinical usage of [sup 99m] Tc-HMPAT was mentioned, the advantage of which is the rapid fixation in the brain tissue and the distribution does not change for long time after the i.v. injection. Hence [sup 99m]Tc-HMPAO is used for the diagnosis of epileptic foci and certain loading tests such as balloon occlusion test, postural test and acetazolamide loading test. (author).

  8. ''Blood flow measurements in the irradiated pig skin using β emitters radionuclides''

    International Nuclear Information System (INIS)

    Non invasive methods of study of the skin blood flow are numerous, but generally do not give any indication on the cutaneous micro-circulatory flow, except for cutaneous laser Doppler. The isotopic exploration of the skin with injected γ radionuclides, even of weak energy, doe snot allow to characterize the skin blood flow, because of the important contribution of the subcutaneous tissues. The use of β emitters energy spectrum, analyzed by different quantitative methods, are proportional to the thickness of the screen localized between the radioactive source and detector. Using simple and complex phantoms composed of tissue equivalent screens, with 32P sources placed at different depths, it was possible to study the degradation of β spectra, simulating respectively the sub-epidermis and sub-dermis vascular levels. A modelization and an experimental study in-vivo are proposed in this work, with 32P phosphate administered intravenously in pigs. (author)

  9. Blood Flow Multiscale Phenomena

    OpenAIRE

    Agić, Ante; Mijović, Budimir; Nikolić, Tatjana

    2007-01-01

    The cardiovascular disease is one of most frequent cause deaths in modern society. The objective of this work is analyse the effect of dynamic vascular geometry (curvature, torsion,bifurcation) and pulsatile blood nature on secondary flow, wall shear stress and platelet deposition. The problem was examined as multi-scale physical phenomena using perturbation analysis and numerical modelling. The secondary flow determined as influence pulsatile pressure, vascular tube time-dependen...

  10. Determination of the amplitude and phase relationships between oscillations in skin temperature and photoplethysmography-measured blood flow in fingertips

    International Nuclear Information System (INIS)

    It is well established that skin temperature oscillations in fingertips coexist with blood flow oscillations and there is a certain correlation between them. At the same time, the reasons for differences in waveform and the delay between the blood flow and temperature oscillations are far from being fully understood. In this study we determine the relationships between spectral components of the blood flow and temperature oscillations in fingertips, and we ascertain the frequency dependences of amplitude attenuation and delay time for the temperature oscillations. The blood flow oscillations were considered as a source of thermal waves propagating from micro-vessels towards the skin surface and manifesting as temperature oscillations. The finger temperature was measured by infrared thermography and blood flow was assessed by photoplethysmography for ten healthy subjects. The time–frequency analysis of oscillations was based on the Morlet wavelet transform. The frequency dependences of delay time and amplitude attenuation in temperature compared with blood flow oscillations have been determined in endothelial (0.005–0.02 Hz) and neurogenic (0.02–0.05 Hz) frequency bands using the wavelet spectra. We approximated the experimental frequency dependences by equations describing thermal wave propagation through the medium and taking into account the thermal properties and thickness of a tissue. Results of analysis show that with the increase of frequency f the delay time of temperature oscillations decreases inversely proportional to f1/2, and the attenuation of the amplitude increases directly proportional to exp f1/2. Using these relationships allows us to increase correlation between the processed temperature oscillations and blood flow oscillations from 0.2 to 0.7 within the frequency interval 0.005–0.05 Hz. The established experimental and theoretical relationships clarify an understanding of interrelation between the dynamics of blood flow and skin

  11. Validation of transit-time flowmetry for chronic measurements of regional blood flow in resting and exercising rats

    Directory of Open Access Journals (Sweden)

    S.L. Amaral

    1997-07-01

    Full Text Available The objective of the present study was to validate the transit-time technique for long-term measurements of iliac and renal blood flow in rats. Flow measured with ultrasonic probes was confirmed ex vivo using excised arteries perfused at varying flow rates. An implanted 1-mm probe reproduced with accuracy different patterns of flow relative to pressure in freely moving rats and accurately quantitated the resting iliac flow value (on average 10.43 ± 0.99 ml/min or 2.78 ± 0.3 ml min-1 100 g body weight-1. The measurements were stable over an experimental period of one week but were affected by probe size (resting flows were underestimated by 57% with a 2-mm probe when compared with a 1-mm probe and by anesthesia (in the same rats, iliac flow was reduced by 50-60% when compared to the conscious state. Instantaneous changes of iliac and renal flow during exercise and recovery were accurately measured by the transit-time technique. Iliac flow increased instantaneously at the beginning of mild exercise (from 12.03 ± 1.06 to 25.55 ± 3.89 ml/min at 15 s and showed a smaller increase when exercise intensity increased further, reaching a plateau of 38.43 ± 1.92 ml/min at the 4th min of moderate exercise intensity. In contrast, exercise-induced reduction of renal flow was smaller and slower, with 18% and 25% decreases at mild and moderate exercise intensities. Our data indicate that transit-time flowmetry is a reliable method for long-term and continuous measurements of regional blood flow at rest and can be used to quantitate the dynamic flow changes that characterize exercise and recovery

  12. Correlation between cerebral oxygen metabolism and cerebral blood flow simultaneously measured before and after acetazolamide administration

    Science.gov (United States)

    Yamaguchi, Hiroichiro; Yamauchi, Hideto; Hazama, Shiro; Hamamoto, Hirotsugu; Inoue, Nobuhiro

    1999-10-01

    The cerebral circulation and metabolism of ten preoperative cardiac surgery patients were assessed. Alterations in regional cerebral blood flow (rCBF), measured by 123I-N- isopropyl-p-iodo-amphetamine single-photon emission computed tomography, and in cerebral oxygen metabolism, simultaneously detected by near-infrared spectroscopy (NIRS) before and after acetazolamide administration, were investigated. The rCBF (ml/min/100 g) increased significantly from 40.21 +/- 7.65 to 56.24 +/- 13.69 (p equals 0.001), and a significant increase in oxyhemoglobin (Oxy-Hb) of 13.9% (p equals 0.0022) and total hemoglobin (Total-Hb) of 5.7% (0.0047) along with a significant decrease in deoxyhemoglobin (Deoxy-Hb) of 8.9% (p equals 0.0414) were observed concomitantly. Thus, the Oxy-Hb/Total- Hb ratio (%Oxy-Hb) rose significantly from 67.26 +/- 9.82% to 72.98 +/- 8.09% (p equals 0.0022). Examination of the relationships between individual parameters showed that the percentage changes in rCBF and Oxy-Hb were significantly correlated (r equals 0.758, p equals 0.011). The percentage changes in rCBF and %Oxy-Hb were also correlated significantly (r equals 0.740, p equals 0.014). In conclusion, this evidence suggested that NIRS is able to detect relative changes in cerebral hemodynamics and reflect luxury perfusion induced by acetazolamide.

  13. Ocular Blood Flow Autoregulation Mechanisms and Methods

    Directory of Open Access Journals (Sweden)

    Xue Luo

    2015-01-01

    Full Text Available The main function of ocular blood flow is to supply sufficient oxygen and nutrients to the eye. Local blood vessels resistance regulates overall blood distribution to the eye and can vary rapidly over time depending on ocular need. Under normal conditions, the relation between blood flow and perfusion pressure in the eye is autoregulated. Basically, autoregulation is a capacity to maintain a relatively constant level of blood flow in the presence of changes in ocular perfusion pressure and varied metabolic demand. In addition, ocular blood flow dysregulation has been demonstrated as an independent risk factor to many ocular diseases. For instance, ocular perfusion pressure plays key role in the progression of retinopathy such as glaucoma and diabetic retinopathy. In this review, different direct and indirect techniques to measure ocular blood flow and the effect of myogenic and neurogenic mechanisms on ocular blood flow are discussed. Moreover, ocular blood flow regulation in ocular disease will be described.

  14. Multivariate evaluation of brain function by measuring regional cerebral blood flow and event-related potentials

    Energy Technology Data Exchange (ETDEWEB)

    Koga, Yoshihiko; Mochida, Masahiko; Shutara, Yoshikazu; Nakagawa, Kazumi [Kyorin Univ., Mitaka, Tokyo (Japan). School of Medicine; Nagata, Ken

    1998-07-01

    To measure the effect of events on human cognitive function, effects of odors by measurement regional cerebral blood flow (rCBF) and P300 were evaluated during the auditory odd-ball exercise. PET showed the increase in rCBF on the right hemisphere of the brain by coffee aroma. rCBF was measured by PET in 9 of right-handed healthy adults men, and P300 was by event-related potential (ERP) in each sex of 20 right-handed healthy adults. ERP showed the difference of the P300 amplitude between men and women, and showed the tendency, by odors except the lavender oil, that women had higher in the P300 amplitude than men. These results suggest the presence of effects on the cognitive function through emotional actions. Next, the relationship between rCBF and ERP were evaluated. The subjects were 9 of the right-handed healthy adults (average: 25.6{+-}3.4 years old). rCBF by PET and P300 amplitude by ERP were simultaneously recorded during the auditory odd-ball exercise using the tone-burst method (2 kHz of the low frequency aimed stimuli and 1 kHz of the high frequency non-aimed stimuli). The rCBF value was the highest at the transverse gyrus of Heschl and the lowest at the piriform cortex among 24 regions of interest (ROI) from both sides. The difference of P300 peak latent time among ROI was almost the same. The brain waves from Cz and Pz were similar and the average amplitude was highest at Pz. We found the high correlation in the right piriform cortex (Fz), and right (Fz, Cz) and left (Cz, Pz) transverse gyrus of Heschl between the P300 amplitude and rCBF. (K.H.)

  15. Multivariate evaluation of brain function by measuring regional cerebral blood flow and event-related potentials

    International Nuclear Information System (INIS)

    To measure the effect of events on human cognitive function, effects of odors by measurement regional cerebral blood flow (rCBF) and P300 were evaluated during the auditory odd-ball exercise. PET showed the increase in rCBF on the right hemisphere of the brain by coffee aroma. rCBF was measured by PET in 9 of right-handed healthy adults men, and P300 was by event-related potential (ERP) in each sex of 20 right-handed healthy adults. ERP showed the difference of the P300 amplitude between men and women, and showed the tendency, by odors except the lavender oil, that women had higher in the P300 amplitude than men. These results suggest the presence of effects on the cognitive function through emotional actions. Next, the relationship between rCBF and ERP were evaluated. The subjects were 9 of the right-handed healthy adults (average: 25.6±3.4 years old). rCBF by PET and P300 amplitude by ERP were simultaneously recorded during the auditory odd-ball exercise using the tone-burst method (2 kHz of the low frequency aimed stimuli and 1 kHz of the high frequency non-aimed stimuli). The rCBF value was the highest at the transverse gyrus of Heschl and the lowest at the piriform cortex among 24 regions of interest (ROI) from both sides. The difference of P300 peak latent time among ROI was almost the same. The brain waves from Cz and Pz were similar and the average amplitude was highest at Pz. We found the high correlation in the right piriform cortex (Fz), and right (Fz, Cz) and left (Cz, Pz) transverse gyrus of Heschl between the P300 amplitude and rCBF. (K.H.)

  16. Assessment of the relationship between standard probe and implantable fiber measurements of cortical bone blood flow: a canine study.

    Science.gov (United States)

    Jain, R; Podworny, N; Anderson, G I; Schemitsch, E H

    1996-07-01

    Laser Doppler flowmetry (LDF) has been used to assess cortical bone blood flow in various clinical situations, such as osteomyelitis and osteonecrosis. Standard metal-sheathed probes containing optical fibers, applied to cortical bone for perfusion measurements, require direct exposure of the bone surface for each measurement, making nonanesthetized assessments over time impractical. Implantable optical fibers offer a noninvasive method for evaluating cortical bone perfusion without repeated surgical exposure of the bone after initial surgical implantation of the fibers. In vitro studies have shown the reliability of laser Doppler (LD) fibers compared with those of the standard probe. This investigation studied the relationship between measurements of cortical bone perfusion obtained by implanted optical (LD) fibers and standard (LDF) probes in vivo. Midshaft tibial fractures were created in the right hindlimb of 11 adult, large (>25 kg) dogs and stabilized by low contact-dynamic compression plate fixation. Cortical bone blood flow was measured by LDF using standard probes and implantable fibers at five sites along the tibia prefracture, postfracture, immediately postplate application, and at 10 weeks postplating, immediately prior to euthanasia. The implantable fibers were secured onto the cortical bone via the plate and led through a percutaneous exit site. Histological examination of the inguinal and popliteal lymph nodes and soft tissue surrounding the fibers revealed mild inflammation. No significant correlation of blood flow assessed by the implantable fibers and standard probe occurred immediately postfracture (r 0.62). However, a statistically significant correlation was seen postplate application at one of the measurement sites in the distal fracture fragment (r = 0.78, P fibers remained intact and functional until an average of 3 weeks at which time they either fractured or were removed by the animals. This is the first in vivo study assessing the

  17. Endoscopic Doppler ultrasound for measurement of azygos blood flow. Validation against thermodilution and assessment of pharmacological effects of terlipressin in portal hypertension

    DEFF Research Database (Denmark)

    Hansen, Erik Feldager; Bendtsen, Flemming; Brinch, K;

    2001-01-01

    BACKGROUND: Endoscopic ultrasound (EUS) is a new modality allowing real-time flow measurements by means of the Doppler technique. The aim of the study was to evaluate azygos blood flow measurements by endoscopic ultrasound. METHODS: Measurements of azygos blood flow by EUS and by the thermodilution...... measurement of the azygos blood flow correlate strongly to the measurements by the thermodilution technique, and EUS is moreover well tolerated by the patients. The method is applicable for monitoring pharmacological effects on the superior porto-systemic collateral circulation and portal venous flow...

  18. Cerebral Blood Flow and Transcranial Doppler Sonography Measurements of CO(2)-Reactivity in Acute Traumatic Brain Injured Patients

    DEFF Research Database (Denmark)

    Reinstrup, Peter; Ryding, Erik Hilmer; Asgeirsson, Bogi;

    2013-01-01

    BACKGROUND: Cerebral blood flow (CBF) measurements are helpful in managing patients with traumatic brain injury (TBI), and testing the cerebrovascular reactivity to CO(2) provides information about injury severity and outcome. The complexity and potential hazard of performing CBF measurements lim...... demonstrating deviation in the same direction during hypocapnia. TCD and CBF measurements both provide useful information on cerebrovascular events which, although not interchangeable, may complement each other in clinical scenarios....

  19. Measurement of regional hepatic blood flow and scintigraphic imaging of portal circulation with /sup 133/Xe

    Energy Technology Data Exchange (ETDEWEB)

    Kroiss, A. (Krankenanstalt der Stadt Wien Rudolfstiftung (Austria) 1. Medizinische Abt.)

    1980-01-01

    Regional hepatic blood flow has been determined by 4 methods with the aid of /sup 133/Xe washout technique: 1. scintisplenoportography (direct application of /sup 133/Xe into the spleen by means of a thin needle); 2. arterial method (/sup 133/Xe is injected into the A. hepatica by means of a catheter); 3. retrograde-venous method (/sup 133/Xe administered by an occluding hepatic vein catheter); 4. percutaneous intrahepatic method (/sup 133/Xe administered directly into the parenchyma by means of a Chiba needle). It was possible to demonstrate that hepatic blood flow values established with the aid of /sup 133/Xe are independent of the form of application (scintisplenoportography, arterial method, retrograde-venous method).

  20. A venous outflow method for measurement of rapid changes of the cerebral blood flow and oxygen consumption in the rat.

    Science.gov (United States)

    Nilsson, B; Siesjö, B K

    1983-01-01

    A technique for continuous measurement of cerebral venous outflow in the rat is described. The method involves cannulation of one retroglenoid vein close to its exit from the skull, and diversion of cerebral venous blood through a closed extracorporal circuit with a drop recording device, the blood being returned to the central venous circulation via a catheter in the external jugular vein. Occlusion of the contralateral retroglenoid vein increases measured flow and minimizes extracerebral contamination of the diverted cerebral venous blood. The venous outflow system is not further isolated from cerebral or potential extracerebral collaterals. Thus, the mass of tissue drained cannot be exactly defined anatomically. However, the experiments involving changes of PP, arterial CO2 tension, and induction of epileptic seizure activity, and simultaneous indirect measurements with radioactive tracer technique, indicate that significant extracerebral contamination does not occur and that in short term measurements the venous outflow represents cerebral blood flow (CBF) in a constant mass of (dorsal and central, mainly forebrain) cerebral tissue. Measurement of arterial blood pressure and pressure in the cisterna magna allows calculation of cerebral perfusion pressure (PP). By simultaneous measurement of arterial and cerebral venous oxygen content changes in cerebral oxygen consumption (CMRO2) can be calculated. The method has been applied to document several situations of transient CBF and CMRO2 changes. PMID:6658967

  1. Dependence of renal blood flow on renal artery stenosis measured using CT angiography

    Energy Technology Data Exchange (ETDEWEB)

    Luedemann, Lutz [Charite - Universitaetsmedizin Berlin (Germany). Dept. of Radiotherapy; Nafz, B.; Persson, P. [Charite - Universitaetsmedizin Berlin (Germany). Inst. for Vegetative Physiology; Elsner, F. [Krankenhaus am Urban, Berlin (Germany). Dept. of Anesthesiology; Grosse-Siestrup, C.; Meissler, M. [Charite - Universitaetsmedizin Berlin (Germany). Experimental Animal Unit; Gutberlet, M. [Charite - Universitaetsmedizin Berlin (Germany). Dept. of Diagnostic and Interventional Radiology; Univ. Leipzig/ Leipzig Heart Center (Germany). Dept. of Diagnostic and Interventional Radiology; Lengsfeld, P.; Voth, M. [Bayer-Schering Pharma AG, Berlin (Germany). Global Medical Affairs Diagnostic Imaging

    2011-03-15

    The present study investigates the suitability of computed tomography angiography (CTA) depicting the degree of renal artery stenosis for estimating renal blood flow (RBF) in a kidney. Materials and Methods: We investigated renal artery stenosis assessment by CTA in eight adult female hybrid pigs with an ultrasound probe implanted at the renal vein for RBF measurement. An inflatable metal-free cuff was placed around the renal artery to control the RBF. The RBF was then reduced in four steps. For each reduced RBF value and baseline RBF, CTA with a reconstructed slice thickness of 0.625 mm was performed in the arterial phase following injection of 80 ml of nonionic intravenous contrast medium. The radius of the stenotic and non-stenotic renal artery segment was measured in the reconstructed images. Results: A significant linear correlation (p < 0.0001) was found between the relative apparent stenosis (calculated as the ratio of the radii of the actual stenotic segment and a non-stenotic renal artery segment) and RBF. The linear regression yielded a slope of 0.57 and a y-axis of 24.1 %. A significant linear correlation (p < 0.0001) was also found between the relative true stenosis (the ratio of the radii of the actual stenotic segment and a non-stenotic renal artery segment at baseline) and the RBF. The linear regression yielded a slope of 0.67 and a y-axis of 13.8 %. Conclusion: The results show that the relative stenosis apparent on CTA differs from the true degree of renal artery stenosis. Nevertheless, the degree of renal artery stenosis determined by CTA provides a reliable estimate of the resulting RBF reduction. (orig.)

  2. A comparison of measurements of cerebral blood flow in the rabbit using laser Doppler spectroscopy and radionuclide labelled microspheres.

    Science.gov (United States)

    Eyre, J A; Essex, T J; Flecknell, P A; Bartholomew, P H; Sinclair, J I

    1988-02-01

    Laser Doppler spectroscopy has been evaluated for the measurement of cerebral blood flow (CBF) by correlation with simultaneous measurements by radionuclide labelled microspheres. The experimental procedures were carried out on five anaesthetised rabbits. The cortical tissue was exposed by means of a small burr hole and illuminated by a helium neon laser (632.8 nm). Reflected light was detected using a silicon photodiode, and CBF was calculated continuously from the power of the frequency weighted Doppler spectrum in the reflected light. Three successive measurements of CBF were made using the microsphere technique. Following an initial baseline measurement, CBF was increased by an infusion of metaraminol and then reduced by controlled haemorrhage. Laser Doppler spectroscopy provided continuous monitoring of blood flow fluctuations and during the haemorrhage it was possible to demonstrate CBF autoregulation until the mean blood pressure fell below 6.7 kPa (50 mmHg). A regression analysis was performed between the simultaneous CBF measurements from the two techniques using a least squares best fit straight line analysis (r = 0.92, P less than 0.001). It was concluded that the flow computed from laser Doppler spectroscopy varied linearly with CBF and offers the unique advantage of continuous and instantaneous measurements even during nonsteady state flow.

  3. Integration of Quantitative Positron Emission Tomography Absolute Myocardial Blood Flow Measurements in the Clinical Management of Coronary Artery Disease.

    Science.gov (United States)

    Gewirtz, Henry; Dilsizian, Vasken

    2016-05-31

    In the >40 years since planar myocardial imaging with(43)K-potassium was introduced into clinical research and management of patients with coronary artery disease (CAD), diagnosis and treatment have undergone profound scientific and technological changes. One such innovation is the current state-of-the-art hardware and software for positron emission tomography myocardial perfusion imaging, which has advanced it from a strictly research-oriented modality to a clinically valuable tool. This review traces the evolving role of quantitative positron emission tomography measurements of myocardial blood flow in the evaluation and management of patients with CAD. It presents methodology, currently or soon to be available, that offers a paradigm shift in CAD management. Heretofore, radionuclide myocardial perfusion imaging has been primarily qualitative or at best semiquantitative in nature, assessing regional perfusion in relative terms. Thus, unlike so many facets of modern cardiovascular practice and CAD management, which depend, for example, on absolute values of key parameters such as arterial and left ventricular pressures, serum lipoprotein, and other biomarker levels, the absolute levels of rest and maximal myocardial blood flow have yet to be incorporated into routine clinical practice even in most positron emission tomography centers where the potential to do so exists. Accordingly, this review focuses on potential value added for improving clinical CAD practice by measuring the absolute level of rest and maximal myocardial blood flow. Physiological principles and imaging fundamentals necessary to understand how positron emission tomography makes robust, quantitative measurements of myocardial blood flow possible are highlighted.

  4. Integration of Quantitative Positron Emission Tomography Absolute Myocardial Blood Flow Measurements in the Clinical Management of Coronary Artery Disease.

    Science.gov (United States)

    Gewirtz, Henry; Dilsizian, Vasken

    2016-05-31

    In the >40 years since planar myocardial imaging with(43)K-potassium was introduced into clinical research and management of patients with coronary artery disease (CAD), diagnosis and treatment have undergone profound scientific and technological changes. One such innovation is the current state-of-the-art hardware and software for positron emission tomography myocardial perfusion imaging, which has advanced it from a strictly research-oriented modality to a clinically valuable tool. This review traces the evolving role of quantitative positron emission tomography measurements of myocardial blood flow in the evaluation and management of patients with CAD. It presents methodology, currently or soon to be available, that offers a paradigm shift in CAD management. Heretofore, radionuclide myocardial perfusion imaging has been primarily qualitative or at best semiquantitative in nature, assessing regional perfusion in relative terms. Thus, unlike so many facets of modern cardiovascular practice and CAD management, which depend, for example, on absolute values of key parameters such as arterial and left ventricular pressures, serum lipoprotein, and other biomarker levels, the absolute levels of rest and maximal myocardial blood flow have yet to be incorporated into routine clinical practice even in most positron emission tomography centers where the potential to do so exists. Accordingly, this review focuses on potential value added for improving clinical CAD practice by measuring the absolute level of rest and maximal myocardial blood flow. Physiological principles and imaging fundamentals necessary to understand how positron emission tomography makes robust, quantitative measurements of myocardial blood flow possible are highlighted. PMID:27245647

  5. Carotid blood flow measured by an ultrasonic volume flowmeter in carotid stenosis and patients with dementia.

    OpenAIRE

    UEMATSU, S.; Folstein, M F

    1985-01-01

    The volume flowmeter is a simple, noninvasive Doppler ultrasound technique that provides accurate measurement of carotid artery diameter and flow. The device provides a useful laboratory test that can aid significantly in diagnosis of carotid stenosis and dementia.

  6. A study on regional cerebral blood flow measurement by N-isopropyl-p-[I-123]iodoamphetamine

    International Nuclear Information System (INIS)

    In vivo characteristics of N-isopropyl-p-[I-123]iodoamphetamine (I-123 IMP) as a potential agent for imaging regional cerebral blood flow (rCBF) were fundamentally studied, and the clinical value of gamma camera rotating SPECT with I-123 IMP was assessed. Brain autoradiography in rats revealed that brain uptake of I-123 IMP is comparable to that described for C-14 iodoantipyrin. In a healthy volunteer, brain uptake was 8.5 % of injected dose at 1.5 hr. Significant uptake of I-123 IMP was observed in the lungs and liver, but not observed in the eyeball or pancreas. Radiation absorbed doses per mCi of I-123 IMP were 0.142 in the brain, 0.178 in the lungs, 0.130 in the liver, 0.038 in the ovaries, 0.027 in the testes, and 0.042 in the total body. A rotating gamma camera for SPECT gave the same linear response to radioactivity as a ring detector, although the latter had better sensitivity and resolution than the former. An increased rCBF was observed with physiological stimulation including left hand movement, reading, and listening, providing three-dimensional mapping of regional cerebral function for kinesthesia. Fifty-three measurements of rCBF were clinically acquired in 42 patients with cerebrovascular disorder. Mean rCBF ranged from 11 to 40 ml/100 g/min. SPECT with I-123 IMP had a significantly high ability to detect ischemic lesions compared with X-ray CT (83 % vs. 41 %). These results indicate the potential benefits of this modality in evaluating cerebral pathophysiology, treatment efficacy, and surgical indications. (Namekawa, K.)

  7. Validity of blood flow measurement using 320 multi-detectors CT and first-pass distribution theory: a phantom study

    Science.gov (United States)

    Chen, Jun; Yu, Xuefang; Xu, Shaopeng; Zhou, Kenneth J.

    2015-03-01

    To evaluate the feasibility of measuring the myocardial blood flow using 320 row detector CT by first-pass technique. Heart was simulated with a container that was filled with pipeline of 3mm diameter; coronary artery was simulated with a pipeline of 2 cm diameter and connected with the simulated heart. The simulated coronary artery was connected with a big container with 1500 ml saline and 150ml contrast agent. One pump linking with simulated heart will withdraw with a speed of 10 ml/min, 15 ml/min, 20 ml/min, 25 ml/min and 30 ml/min. First CT scan starts after 30 s of pumpback with certain speed. The second CT scan starts 5 s after first CT scans. CT images processed as follows: The second CT scan images subtract first CT scan images, calculate the increase of CT value of simulated heart and the CT value of the unit volume of simulated coronary artery and then to calculate the total inflow of myocardial blood flow. CT myocardial blood flows were calculated as: 0.94 ml/s, 2.09 ml/s, 2.74 ml/s, 4.18 ml/s, 4.86 ml/s. The correlation coefficient is 0.994 and r2 = 0.97. The method of measuring the myocardial blood flow using 320 row detector CT by 2 scans is feasible. It is possible to develop a new method for quantitatively and functional assessment of myocardial perfusion blood flow with less radiation does.

  8. Study of Estimation Method for Unsteady Inflow Velocity in Two-Dimensional Ultrasonic-Measurement-Integrated Blood Flow Simulation.

    Science.gov (United States)

    Kadowaki, Hiroko; Hayase, Toshiyuki; Funamoto, Kenichi; Taniguchi, Nobuyuki

    2016-02-01

    Information on hemodynamics is essential for elucidation of mechanisms and development of novel diagnostic methods for circulatory diseases. Two-dimensional ultrasonic-measurement-integrated (2D-UMI) simulation can correctly reproduce an intravascular blood flow field and hemodynamics by feeding back an ultrasonic measurement to the numerical blood flow simulation. In this method, it is critically important to give the correct cross-sectional average inflow velocity (inflow velocity) as the boundary condition. However, systematic study has not been done on the relative validity and effectiveness of existing inflow velocity estimation methods for various target flow fields. The aim of this study was to examine the existing methods systematically and to establish a method to accurately estimate inflow velocities for various vessel geometries and flow conditions in 2D-UMI simulations. A numerical experiment was performed for 2D-UMI simulation of blood flow models in a straight vessel with inflow velocity profiles symmetric and asymmetric to the vessel axis using existing evaluation functions based on Doppler velocity error for the inflow velocity estimation. As a result, it was clarified that a significantly large estimation error occurs in the asymmetric flow due to a nonfeedback domain near the downstream end of the calculation domain. Hence, a new inflow velocity estimation method of 2D-UMI simulation is proposed in which the feedback and evaluation domains are extended to the downstream end. Further numerical experiments of 2D-UMI simulation for two realistic vessel geometries of a healthy blood vessel and a stenosed one confirmed the effectiveness of the proposed method. PMID:26241967

  9. Flow measurements in a blood-perfused collagen vessel using x-ray micro-particle image velocimetry.

    Science.gov (United States)

    Antoine, Elizabeth; Buchanan, Cara; Fezzaa, Kamel; Lee, Wah-Keat; Rylander, M Nichole; Vlachos, Pavlos

    2013-01-01

    Blood-perfused tissue models are joining the emerging field of tumor engineering because they provide new avenues for modulation of the tumor microenvironment and preclinical evaluation of the therapeutic potential of new treatments. The characterization of fluid flow parameters in such in-vitro perfused tissue models is a critical step towards better understanding and manipulating the tumor microenvironment. However, traditional optical flow measurement methods are inapplicable because of the opacity of blood and the thickness of the tissue sample. In order to overcome the limitations of optical method we demonstrate the feasibility of using phase-contrast x-ray imaging to perform microscale particle image velocimetry (PIV) measurements of flow in blood perfused hydrated tissue-representative microvessels. However, phase contrast x-ray images significantly depart from the traditional PIV image paradigm, as they have high intensity background, very low signal-to-noise ratio, and volume integration effects. Hence, in order to achieve accurate measurements special attention must be paid to the image processing and PIV cross-correlation methodologies. Therefore we develop and demonstrate a methodology that incorporates image preprocessing as well as advanced PIV cross-correlation methods to result in measured velocities within experimental uncertainty.

  10. Flow measurements in a blood-perfused collagen vessel using x-ray micro-particle image velocimetry.

    Directory of Open Access Journals (Sweden)

    Elizabeth Antoine

    Full Text Available Blood-perfused tissue models are joining the emerging field of tumor engineering because they provide new avenues for modulation of the tumor microenvironment and preclinical evaluation of the therapeutic potential of new treatments. The characterization of fluid flow parameters in such in-vitro perfused tissue models is a critical step towards better understanding and manipulating the tumor microenvironment. However, traditional optical flow measurement methods are inapplicable because of the opacity of blood and the thickness of the tissue sample. In order to overcome the limitations of optical method we demonstrate the feasibility of using phase-contrast x-ray imaging to perform microscale particle image velocimetry (PIV measurements of flow in blood perfused hydrated tissue-representative microvessels. However, phase contrast x-ray images significantly depart from the traditional PIV image paradigm, as they have high intensity background, very low signal-to-noise ratio, and volume integration effects. Hence, in order to achieve accurate measurements special attention must be paid to the image processing and PIV cross-correlation methodologies. Therefore we develop and demonstrate a methodology that incorporates image preprocessing as well as advanced PIV cross-correlation methods to result in measured velocities within experimental uncertainty.

  11. Micro-particle image velocimetry measurement of blood flow: validation and analysis of data pre-processing and processing methods

    International Nuclear Information System (INIS)

    The intent of this paper is to investigate the application of a pre-processing method previously validated on glycerol to blood flows in microchannels and to compare the accuracy of results obtained when applied to a non-homogeneous fluid such as blood with results from previously applied processing methods for blood data. Comparisons of common processing methods are desired for a clear measure of accuracy in order to make recommendations for various flows. It is hypothesized that increasing the correlation window overlap improves the profile prediction. The amount of correlation window overlap and window shape in the processing of data have a significant effect on the results. Image pre-processing is explored to improve the correlation using the ‘image overlapping’ which is extended to the case of blood and the blood-specific pre-processing ‘base-clipping’ or ‘thresholding’ technique currently applied to blood. Both pre-processing methods are tested with multiple processing methods for two channel geometries: a straight rectangular channel and a Y-channel resulting in a controlled shear flow. The resulting profiles and calculations demonstrate that ‘image-overlapping’ is found to achieve a profile closer to the predicted theoretical profile than current blood pre-processing methods when both are applied to the same set of data and both are superior to conventional cross-correlation on its own. In all cases, pre-processing decreases the smoothness of the predicted profile. The use of ‘image-overlapping’ is shown to have greater accuracy when calculating the shear rate at the wall of the channel as well. (paper)

  12. Endoscopic Doppler ultrasound for measurement of azygos blood flow. Validation against thermodilution and assessment of pharmacological effects of terlipressin in portal hypertension

    DEFF Research Database (Denmark)

    2001-01-01

    BACKGROUND: Endoscopic ultrasound (EUS) is a new modality allowing real-time flow measurements by means of the Doppler technique. The aim of the study was to evaluate azygos blood flow measurements by endoscopic ultrasound. METHODS: Measurements of azygos blood flow by EUS and by the thermodilution...... technique were compared in 20 patients with portal hypertension. The ability of EUS flowmetry to detect changes in the azygos and portal venous flow after an intravenous dose of 2 mg of terlipressin was evaluated in 13 of the patients in a double-blind, randomized, placebo-controlled, cross-over design....... RESULTS: The EUS Doppler and thermodilution measurements correlated significantly (R=0.81, P blood flow was found to be 14% higher by the EUS method than by thermodilution. The coefficient of variation of the EUS Doppler measurements of the azygos blood flow was 14.8%. After...

  13. Regional pulmonary blood flow measurement in humans with electron beam computed tomography

    International Nuclear Information System (INIS)

    Electron beam computed tomography (EBCT) is a potentially useful modality to quantitate regional pulmonary flow (RPF) with minimal invasiveness, in part because it has good spatial and temporal resolution. The present studies used a single compartment model of indicator transport and EBCT to measure regional tissue flow in the lungs of human subjects. The model postulates that flow is proportional to maximal enhancement and assumes complete tissue accumulation of indicator before significant indicator washout (WO). EBCT flow studies were retrospectively analyzed with respect to regional pulmonary flow (RPF) in 10 adult patients who had undergone clinically indicated or research cardiovascular studies. Time density curves from the left atrial (LA) cavity and one-third segments of left (LL) and right (RL) lungs (A: anterior, M: middle and P: posterior segments) were used to calculate RPF. Washout was determined as the percent of the LA curve at the time of peak parenchymal opacification using gamma curve fits to both tissue data and the LA curve data. Mean ± standard deviation RPF in ml/min/ml was 0.8 ± 0.4, 1.1 ± 0.4 and 1.3 ± 0.4 for A, M and P respectively for one-third regions in the left lung. Similar results were found in the right lung. No difference in RPF was found when images were measured either by including the largest of visible parenchymal vessels or when such vessels were excluded. Flow in A of LL and RL was less than that in M or P. Average WO was about 10%, with a range of 0--41% of the LA curve area. There was no significant difference between one-third segment WO using pairwise comparison on the left and right sides when tested separately. RPF values were greater in the posterior vs anterior regions of these supine patients. In conclusion, EBCT can detect gravity related flow differences in the human lung. EBCT has potential for clinical assessment of absolute regional pulmonary flow determination in animals and man

  14. Depth discrimination in acousto-optic cerebral blood flow measurement simulation

    Science.gov (United States)

    Tsalach, A.; Schiffer, Z.; Ratner, E.; Breskin, I.; Zeitak, R.; Shechter, R.; Balberg, M.

    2016-03-01

    Monitoring cerebral blood flow (CBF) is crucial, as inadequate perfusion, even for relatively short periods of time, may lead to brain damage or even death. Thus, significant research efforts are directed at developing reliable monitoring tools that will enable continuous, bed side, simple and cost-effective monitoring of CBF. All existing non invasive bed side monitoring methods, which are mostly NIRS based, such as Laser Doppler or DCS, tend to underestimate CBF in adults, due to the indefinite effect of extra-cerebral tissues on the obtained signal. If those are to find place in day to day clinical practice, the contribution of extra-cerebral tissues must be eliminated and data from the depth (brain) should be extracted and discriminated. Recently, a novel technique, based on ultrasound modulation of light was developed for non-invasive, continuous CBF monitoring (termed ultrasound-tagged light (UTL or UT-NIRS)), and shown to correlate with readings of 133Xe SPECT and laser Doppler. We have assembled a comprehensive computerized simulation, modeling this acousto-optic technique in a highly scattering media. Using the combination of light and ultrasound, we show how depth information may be extracted, thus distinguishing between flow patterns taking place at different depths. Our algorithm, based on the analysis of light modulated by ultrasound, is presented and examined in a computerized simulation. Distinct depth discrimination ability is presented, suggesting that using such method one can effectively nullify the extra-cerebral tissues influence on the obtained signals, and specifically extract cerebral flow data.

  15. Measurement of aortic blood flow by magnetic resonance below and above the origin of the coronary arteries in postmenopausal hormone replacement therapy

    DEFF Research Database (Denmark)

    Sørensen, Morten Beck; Fritz-Hansen, Thomas; Jensen, Henrik Halvor;

    2004-01-01

    PURPOSE: Principal blood flow measures might be assessable by velocity-encoded cine magnetic resonance (VENC MR) of aortic blood flow. The feasibility of using VENC MR for clinical research was tested in a contemporary and controversial human model: the effects of 17beta-estradiol (E) and cyclic...

  16. Napoleon Cybulski--Polish pioneer in developing of the device for measuring blood flow velocity.

    Science.gov (United States)

    Pawlik, W W; Konturek, S J; Bilski, R

    2006-04-01

    Napoleon Cybulski (1854-1919) was the most prominent Polish physiologist who chaired the Department of Physiology at the Faculty of Medicine of Jagiellonian University between 1885 and 1919. One of his greatest achievements was the construction of a device for precise measurements of blood movement in the vessels - the photohemotachometer, which provided a better insight into the physiology and pathophysiology of the circulatory system. In the field of endocrinology Cybulski together with Szymonowicz, found out that adrenal extracts contain biologically active substances that elevate blood pressure. He was also a constructor of an extremely clever microcalorimeter to measure the quantity of heat produced during isolated muscle contraction. He applied, for the first time, condensator discharges to stimulate nerves and analyzed changes in the excitability of the muscles. Cybulski proved that the cause of the electrical excitability of tissue depends on the electrical energy and the time of its duration. Together with Beck, he performed the experiments on the sensory centers in the central nervous system by means of the observations of the electrical evoked potentials. They discovered the continuous electrical oscillations in the brain - the brain waves and recorded the negative electrical potentials in certain brain areas induced by sensory impulses coming from the periphery. Using this technique Beck and Cybulski localized various centers in the brain of dogs and Macaccus rhesus monkeys. The names of Beck and Cybulski were quoted in many publications on neurophysiology and electroencephalography. The present paper describes Napoleon Cybulski as a constructor of an original instrument for studying the movement of blood under various experimental conditions an emphasizes the contribution of this invention to the development of physiology.

  17. Presymptomatic cerebral blood flow changes in CHMP2B mutation carriers of familial frontotemporal dementia (FTD-3), measured with MRI

    DEFF Research Database (Denmark)

    Lunau, Line Andersen; Mouridsen, Kim; Rodell, Anders;

    2012-01-01

    OBJECTIVES: To assess functional changes measured by cerebral blood flow (CBF) in the presymptomatic stage of frontotemporal dementia linked to chromosome 3 (FTD-3) caused by a truncating mutation in CHMP2B. DESIGN: Case-control study. SETTING: A memory clinic and tertiary referrals centre...... changes in brain tissue perfusion were measured as CBF with two different MR techniques, gradient echo (GRE) and spin echo (SE), focusing on CBF in all cerebral vessels (GRE) and cerebral capillaries (SE), respectively. As planned, data analysis included co-registration of perfusion images to structural T...

  18. Noninvasive xenon-133 measurements of cerebral blood flow using stationary detectors compared with dynamic emission tomography

    DEFF Research Database (Denmark)

    Schroeder, T; Vorstrup, S; Lassen, N A;

    1986-01-01

    Repeated bedside measurements of CBF have been made possible by the recent development of a mobile unit with 10 stationary detectors using the intravenous xenon-133 method. To evaluate this technique, comparative CBF studies at rest and following the application of a cerebral vasodilatory stimulus...... (acetazolamide, 1 g i.v.) were performed with the mobile equipment and with xenon-133 single-photon emission inhalation tomography in patients with cerebrovascular disease. The CBF level and the flow response to acetazolamide as determined with the two methods were well correlated, although at low flow levels...... the stationary detectors yielded somewhat lower CBF values than did emission tomography. Considering the side-to-side asymmetry, an excellent correlation was obtained. Using the initial slope index, the stationary detectors revealed quantitatively 83% of the interhemispheric asymmetry and 63% of the asymmetry...

  19. Quantitative measurement of cerebral blood flow in a juvenile porcine model by depth-resolved near-infrared spectroscopy

    Science.gov (United States)

    Elliott, Jonathan T.; Diop, Mamadou; Tichauer, Kenneth M.; Lee, Ting-Yim; Lawrence, Keith St.

    2010-05-01

    Nearly half a million children and young adults are affected by traumatic brain injury each year in the United States. Although adequate cerebral blood flow (CBF) is essential to recovery, complications that disrupt blood flow to the brain and exacerbate neurological injury often go undetected because no adequate bedside measure of CBF exists. In this study we validate a depth-resolved, near-infrared spectroscopy (NIRS) technique that provides quantitative CBF measurement despite significant signal contamination from skull and scalp tissue. The respiration rates of eight anesthetized pigs (weight: 16.2+/-0.5 kg, age: 1 to 2 months old) are modulated to achieve a range of CBF levels. Concomitant CBF measurements are performed with NIRS and CT perfusion. A significant correlation between CBF measurements from the two techniques is demonstrated (r2=0.714, slope=0.92, p<0.001), and the bias between the two techniques is -2.83 mL.min-1.100 g-1 (CI0.95: -19.63 mL.min-1.100 g-1-13.9 mL.min-1.100 g-1). This study demonstrates that accurate measurements of CBF can be achieved with depth-resolved NIRS despite significant signal contamination from scalp and skull. The ability to measure CBF at the bedside provides a means of detecting, and thereby preventing, secondary ischemia during neurointensive care.

  20. Bone blood flow and metabolism in humans

    DEFF Research Database (Denmark)

    Heinonen, Ilkka; Kemppainen, Jukka; Kaskinoro, Kimmo;

    2012-01-01

    Human bone blood flow and metabolism during physical exercise remains poorly characterised. In the present study we measured femoral bone blood flow and glucose uptake in young healthy subjects by positron emission tomography in three separate protocols. In six women, blood flow was measured...... in femoral bone at rest and during one leg intermittent isometric exercise with increasing exercise intensities. In nine men, blood flow in femur was determined at rest and during dynamic one leg exercise, and two other physiological perturbations: moderate systemic hypoxia (14 O(2) ) at rest and during...... exercise, and during intra-femoral infusion of high-dose adenosine. Bone glucose uptake was measured at rest and during dynamic one leg exercise in five men. The results indicate that isometric exercise increased femoral bone blood flow from rest (1.8 ± 0.6 ml/100g/min) to low intensity exercise (4.1 ± 1...

  1. Effect of Kanji and Kana reading on cerebral blood flow patterns measured by PET

    International Nuclear Information System (INIS)

    To investigate the respective functions of pathways in processing visual information from different types of symbols, by positron emission tomography (PET) we examined the effect on cerebral blood flow (CBF) of reading the Japanese morphogram (kanji) versus the syllabogram (kana). Nine Japanese men were presented with three visual conditions in random order 2 minutes before the scan: eyes open controls, kanji morphogram reading, and kana syllabogram reading. Three words written in kanji or kana were shown, and subjects were instructed to read them silently and to identify the word unrelated logically to the other two. The reading and analyzing tasks activated wide areas of vision-related cortices. The comparison of the kanji and kana readings showed higher metabolism, with the former only in the posterior part of the primary visual cortex. Most of the CBF increases were common for both stimuli, although the patterns of these increases differed slightly. The correlation matrix of CBF change in the left hemisphere showed a ventral connection in kanji reading and a dorsal connection in kana reading. Our results suggest there is a functional differentiation in the brain between patterned and sequential perception when reading Japanese morphograms and syllabograms. (author)

  2. Integrated Measurements of Electrical Activity, Oxygen Tension, Blood Flow, and Ca2+ -Signaling in Rodents In Vivo

    DEFF Research Database (Denmark)

    Mathiesen, Claus; Thomsen, Kirsten; Lauritzen, Martin

    2014-01-01

    in rodent preparation. We also describe methods for recording of cerebral blood flow (CBF), tissue partial pressure of oxygen (tpO2), and cytosolic calcium transients. We finally give examples where electrophysiology, blood flow, metabolism, and calcium transients have been studied together....

  3. Prognostic value of blood flow measurements using arterial spin labeling in gliomas.

    Directory of Open Access Journals (Sweden)

    Julia Furtner

    Full Text Available The period of event-free survival (EFS within the same histopathological glioma grades may have high variability, mainly without a known cause. The purpose of this study was to reveal the prognostic value of quantified tumor blood flow (TBF values obtained by arterial spin labeling (ASL for EFS in patients with histopathologically proven astrocytomas independent of WHO (World Health Organization grade. Twenty-four patients with untreated gliomas underwent tumor perfusion quantification by means of pulsed ASL in 3T. The clinical history of the patients was retrospectively extracted from the local database. Six patients had to be excluded due to insufficent follow-up data for further evaluation or histopathologically verified oligodendroglioma tumor components. Receiver operating characteristic (ROC curves were used to define an optimal cut-off value of maximum TBF (mTBF values for subgrouping in low-perfused and high-perfused gliomas. Kaplan-Meier curves and Cox proportional hazard regression model were used to determine the prognostic value of mTBF for EFS. An optimal mTBF cut-off value of 182 ml/100 g/min (sensitivity  = 83%, specificity  = 100% was determined. Patients with low-perfused gliomas had significantly longer EFS compared to patients with high-perfused gliomas (p = 0.0012 independent of the WHO glioma grade. Quantified mTBF values obtained by ASL offer a new and totally non-invasive marker to prognosticate the EFS, independently on histopathological tumor grading, in patients with gliomas.

  4. Simultaneous measurement of cerebral blood flow and oxygen extraction fraction by positron emission tomography: theoretical study and experimental evidence of cerebral blood flow measurement with the C15O2 continuous inhalation technique

    International Nuclear Information System (INIS)

    The method of the continuous inhalation technique of oxygen-15 labelled CO2 coupled with positron emission tomography for the measurement of cerebral blood flow (C.B.F.) is described. An indirect experimental verification that this technique allowed the measurement of C.B.F. has been carried out in baboons by showing the expected change in the measured parameter with variations in the PaCO2. A critical investigation of the C15O2 model was performed. The amount of tracer present in the cerebral vascular pool has a negligible effect on C.B.F. value. The use of a mean brain-blood partition coefficient of water instead of that specific to gray or to white matter is commented upon, and its influence on the final C.B.F. value is studied. Lastly, the problem of the limited diffusion of water across the blood-brain-barrier is discussed. The study of the combined effects of gray-white mixing and limited wates extraction of the C.B.F. value shows that the C15O2 technique tends to understimate real C.B.F., and that this error is more severe with high flows and even gray white mixing. These limitations do not depart from the possibility to estimate in the same brain locus not only C.B.F. but oxygen utilization as well by the consecutive inhalation of C15O2 and 15O2. The advantages of this possibility has already been shown in a number of clinical studies

  5. Studies on 133Xe wash-out from human skin: quantitative measurements of blood flow in normal and corticosteroid-treated skin

    International Nuclear Information System (INIS)

    Blood flow was measured by the 133Xe technique in normal and corticosteroid-treated skin. Epicutaneous and intracutaneous methods of tracer application were compared in normal skin. The two labeling methods were equally suitable for measuring cutaneous blood flow provided calculations in both cases were based on a biexponential resolution of the wash-out curve in its cutaneous and subcutaneous components and provided the traumatic hyperemia phase was considered, when intracutaneous application of the tracer was used. Results were invalidated if calculations were based on initial slope of the washout curves. Topical application of beta-methasone valerate resulted in a reduction in cutaneous blood flow as measured by the intracutaneous technique with curve resolution, whereas no effect could be demonstrated when calculations were based on the initial slopes of the curves. The 133Xe technique is a simple and reliable method for measuring cutaneous blood flow, which might prove useful in estimations of penetration ability and potency of topical corticosteroids

  6. Minimal-flow xenon and semiclosed circuit anesthesia for computed tomographic measurement of local cerebral blood flow (LCBF)

    International Nuclear Information System (INIS)

    For the purpose of decreasing the volume of expensive xenon, anesthesia with minimal-flow xenon and semiclosed circuit were induced for computed tomographic LCBF measurement. Eighteen patients with ischemic cerebral disease were studied. Xenon inhalation programs were subdivided into three groups, each of them consisted of 6 patients. The formula for calculating fresh gas flow for low flow semiclosed circuit was introduced according to Shimoji's which was based on the original formula of Foldes. O2 concentration in circuit was predicted to be 25%. Mean xenon uptake for initial 20 minutes was predicted to be125 ml/min. or 360 ml/min. The first group started xenon inhalation during pure xenon inflow into semic losed circuit for two minutes and followed by about 68% xenon in O2 inhalation for 23 munites. FXe and VXe were fixed at 700 ml/min and 360 ml/min respectively. The second group was set at the same conditions as the first group except FXe and VXe as shown in Fig.2. The third group inhaled about 63% xenon-oxygen mixture affer four minutes pure xenon inflow. Xenon concentrations in trachea, carotid artery and jugular vein were estimated from the conversion into equivalent enhancement in CT units for every four minutes on line. Fig. 3 shows the O2 concentration change in semiclosed circuit, endtidal CO2 tension and percent change of mean arterial pressure. After 20 minutes xenon inhalation O2 concentration in each group closed to 25% which was predicted O2 concentration of the third group closed more rapidly to 25% than other groups. Normocarbia and stable hemodynamics could be confirmed throughout the procedures in each group. Fig. 5 shows xenon washin curves in trachea and xenon concentration change in carotid artery and jugular vein during xenon inhalation. The washin curves in trachea are quite different in each group. (J.P.N.)

  7. Evaluation of copper(II)-pyruvaldehyde bis (N-4-methylthiosemicarbazone) for tissue blood flow measurement using a trapped tracer model

    International Nuclear Information System (INIS)

    We have investigated the application of a simple trapped tracer model to measurements of tissue 64Cu-PTSM uptake combined with continuous arterial sampling. A dual-tracer method was used to compare blood flow estimated by 64Cu-PTSM with values derived from measurements using cobalt-57 microspheres in the rat. Prolonged retention of 64Cu-PTSM following intravenous administration was initially confirmed in both normal tissues and tumours. After intraventricular 64Cu-PTSM infusion, cumulative arterial 64Cu activity increased progressively, and after extraction in n-octanol was found to plateau to levels corresponding with those reached following administration of 57Co microspheres. Rapid and species-dependent rates of 64Cu-PTSM decomposition to non-extractable 64Cu complexes were found in rat and human blood in vitro (70% ± 6% and 43% ± 5% respectively at 16 min), demonstrating the need for immediate processing of arterial samples. Close agreement was found between blood flow estimated by 64Cu-PTSM and 57Co microsphere methods in tissues of low to moderate flow: muscle (0.01, 0.08, 0.07 ml/min per gram; mean difference, mean 64Cu, mean 57Co), brain (0.09, 0.52, 0.43 ml/min per gram) and kidney (-0.16, 2.29, 2.45 ml/min per gram). Estimates of cardiac output also compared favourably between the two methods (5.7, 59.8, 54.1 ml/min). (orig./MG)

  8. [Liver cirrhosis and portal hypertension: non-invasive measurement of blood flow in the portal vein with Doppler-duplex].

    Science.gov (United States)

    Fernández, M; Chesta, J; Jirón, M I; Mánquez, P; Brahm, J

    1991-05-01

    Doppler-duplex has been widely used to quantify blood flow. Nevertheless, its usefulness in assessing portal vein flow (PVF) has been questioned due to technical problems: vessel cross sectional area measurements, interobserver variability, and PVF changes related to physiological events. This study was aimed to measure PVF in patients with cirrhosis and portal hypertension, to estimate changes in PVF during the respiratory cycle, and to evaluate intraobserver variability of Doppler-duplex technique. Twenty-two patients with liver cirrhosis and portal hypertension and 22 healthy subjects were included. One operator made 6 measurements of portal vein diameter (D) and mean flow velocity in inspiration and aspiration. Area of the vessel (A) and PVF were calculated by a microprocessor. Interobserver variability was estimated for each subject and a mean was determined for each group. In the control group, PVF was 901 +/- 39 ml/min in inspiration and 633 +/- 38 ml/min in aspiration; p espiration in both groups. The Doppler-duplex method evaluation of PVF has an important intraobserver variability (18.3 +/- 1.6%). Then, changes in PVF less than 20% are not accurately measured by this technique. PMID:1844290

  9. Local Control of Blood Flow

    Science.gov (United States)

    Clifford, Philip S.

    2011-01-01

    Organ blood flow is determined by perfusion pressure and vasomotor tone in the resistance vessels of the organ. Local factors that regulate vasomotor tone include myogenic and metabolic autoregulation, flow-mediated and conducted responses, and vasoactive substances released from red blood cells. The relative importance of each of these factors…

  10. Perfusion MRI (dynamic susceptibility contrast imaging) with different measurement approaches for the evaluation of blood flow and blood volume in human gliomas

    Energy Technology Data Exchange (ETDEWEB)

    Thomsen, H. (Den Sundhedsfaglige Kandidatuddannelse, Aarhus Universitet Bygning 1264, Aarhus (Denmark); University College Nordjylland, Aalborg (Denmark)), Email: hnt@ucn.dk; Steffensen, E. (Aalborg Hospital/Aarhus University Hospital, Department of Radiology, Aalborg (Denmark)); Larsson, E. M. (Aalborg Hospital/Aarhus University Hospital, Department of Radiology, Aalborg (Denmark); Uppsala University Hospital, Department of Radiology, Uppsala (Sweden))

    2012-02-15

    Background. Perfusion magnetic resonance imaging (MRI) is increasingly used in the evaluation of brain tumors. Relative cerebral blood volume (rCBV) is usually obtained by dynamic susceptibility contrast (DSC) MRI using normal appearing white matter as reference region. The emerging perfusion technique arterial spin labelling (ASL) presently provides measurement only of cerebral blood flow (CBF), which has not been widely used in human brain tumor studies. Purpose. To assess if measurement of blood flow is comparable with measurement of blood volume in human biopsy-proven gliomas obtained by DSC-MRI using two different regions for normalization and two different measurement approaches. Material and Methods. Retrospective study of 61 patients with different types of gliomas examined with DSC perfusion MRI. Regions of interest (ROIs) were placed in tumor portions with maximum perfusion on rCBF and rCBV maps, with contralateral normal appearing white matter and cerebellum as reference regions. Larger ROIs were drawn for histogram analyses. The type and grade of the gliomas were obtained by histopathology. Statistical comparison was made between diffuse astrocytomas, anaplastic astrocytomas, and glioblastomas. Results. rCBF and rCBV measurements obtained with the maximum perfusion method were correlated when normalized to white matter (r = 0.60) and to the cerebellum (r = 0.49). Histogram analyses of rCBF and rCBV showed that mean and median values as well as skewness and peak position were correlated (0.61 < r < 0.93), whereas for kurtosis and peak height, the correlation coefficient was about 0.3 when comparing rCBF and rCBV values for the same reference region. Neither rCBF nor rCBV quantification provided a statistically significant difference between the three types of gliomas. However, both rCBF and rCBV tended to increase with tumor grade and to be lower in patients who had undergone resection/treatment. Conclusion. rCBF measurements normalized to white matter

  11. Label free imaging system for measuring blood flow speeds using a single multi-mode optical fiber (Conference Presentation)

    Science.gov (United States)

    Sigal, Iliya; Caravaca Aguirre, Antonio M.; Gad, Raanan; Piestun, Rafael; Levi, Ofer

    2016-03-01

    We demonstrate a single multi-mode fiber-based micro-endoscope for measuring blood flow speeds. We use the transmission-matrix wavefront shaping approach to calibrate the multi-mode fiber and raster-scan a focal spot across the distal fiber facet, imaging the cross-polarized back-reflected light at the proximal facet using a camera. This setup allows assessment of the backscattered photon statistics: by computing the mean speckle contrast values across the proximal fiber facet we show that spatially-resolved flow speed maps can be inferred by selecting an appropriate camera integration time. The proposed system is promising for minimally-invasive studies of neurovascular coupling in deep brain structures.

  12. Quantitation of contact allergy in guinea pigs by measuring changes in skin blood flow and skin fold thickness

    DEFF Research Database (Denmark)

    Andersen, Klaus Ejner; Staberg, B

    1985-01-01

    Skin blood flow determined by laser Doppler flowmetry (LDF) and skin fold thickness (SFT) have been used to quantitate allergic contact dermatitis in the guinea pig maximization test (GPMT) using chlorocresol as the allergen. The closed patch test procedure itself influenced both LDF and SFT...... measurements when determined in 12 sham-treated guinea pigs. The LDF was maximal at 24 hours and the SFT at 48 hours. Before correlating the quantitative measurements with the conventional visual scoring in test and control animals the value from a nearby control site was subtracted from the test site values....... The correlations were highly significant (p less than 0.001-0.05) indicating that the quantitative methods were useful supplements to the visual scoring as a measure of interobserver and interlaboratory differences....

  13. Uteroplacental blood flow in pre-eclampsia measurements with /sup 113 m/In and a computer-linked gamma camera

    International Nuclear Information System (INIS)

    Uteroplacental blood flow was measured with a computer-linked gamma camera after intravenous injection of 1 mCi 113In. Results of the measurements from 32 pre-eclamptic pregnancies and 37 normal controls are compared. The uteroplacental blood flow was measured as an index calculated from the rise time and maximum activity of the isotope accumulation curve. The uteroplacental blood flow was reduced with 50% in pre-eclampsia. In severe pre-eclampsia it was more compromised than in mild pre-eclampsia. A diminished uteroplacental blood flow was found in pre-eclampsia even in the absence of intrauterine growth retardation. The maternal placental circulation in the supine position was reduced with one third compared to that in the left lateral recumbent position

  14. Near-infrared spectroscopy extended with indocyanine green dye dilution for cerebral blood flow measurement: Median values in healthy volunteers

    Science.gov (United States)

    Mudra, R.; Muroi, C.; Niederer, P.; Keller, E.

    2008-09-01

    The cerebral blood flow (CBF) is an important vital parameter in neurointensive care. Currently, there is no non-invasive method for its measurement that can easily be applied at the bedside. A new tool to determine CBF is based on near-infrared spectroscopy (NIRS) applied together with indocyanine green (ICG) dye dilution. From a bilateral measurement on selected regions on the head of infrared (IR) absorption at various wavelengths during the dilution maneuver, the vascular perfusion characteristics of the two brain hemispheres can be determined in terms of mean transit time (mtt) of ICG, cerebral blood volume (CBV) and CBF. So far, on nine healthy volunteers, NIRS ICG dye dilution bihemispheric measurements were performed, which yielded to mtt given as median (range) of 9.3 s (5.1-16.3 s), CBV of 3.5 ml/100 g (1.7-4.1 ml/100 g), and CBF of 18.2 ml/(100 g×min) [11.1-48.6 ml/(100 g×min)]. Additionally, the blood flow index (BFI) was calculated with BFI= 13.8 mg/(100 g×s) [6.6-15.2 mg/(100 g×s)]. The Spearman rank correlation coefficient between CBF and BFI was RS = 0.76. However, as the Bland & Altman plot between CBFNIRS and the CBFBFI documents, the limits of agreement are rather wide (21.9±6.7). Under physiological conditions in healthy volunteers, no differences could be detected between the hemispheres.

  15. Skin blood flow changes in anaesthetized humans: comparison between skin thermal clearance and finger pulse amplitude measurement.

    Science.gov (United States)

    Saumet, J L; Leftheriotis, G; Dittmar, A; Delhomme, G; Degoute, C S

    1986-01-01

    The effect of general anaesthesia on skin blood flow in the left hand, measured by a new non-invasive probe using the thermal clearance method was examined. A mercury silastic gauge was placed around the third left finger and the plethysmographic wave amplitude was recorded to measure changes in finger pulse amplitude. Heart rate (HR), mean arterial blood pressure (MABP) and skin temperature were also recorded. General anaesthesia was induced by droperidol and phenoperidine injection and propanidid infusion in eight female patients. Skin thermal clearance, plethysmographic wave amplitude, HR, MABP and skin temperature were 0.40 +/- 0.02 w X m-1 degree C-1, 9 +/- 1 mm, 98 +/- 5 beats X min-1, 12.50 +/- 0.93 kPa and 33.3 +/- 3.4 degrees C respectively. The minimal value of MABP was 9.58 +/- 1.06 kPa, whereas skin thermal clearance, plethysmographic wave amplitude, HR and skin temperature increased to 0.45 +/- 0.02 w X m-1 degree C-1, 29 +/- 3 mm, 110 +/- 4 beats X min-1 and 34.4 +/- 0.4 degrees C. Changes in skin thermal clearance correlated well with plethysmographic wave amplitude. Statistically significant changes in these two parameters occurred before significant change in HR, MABP or skin temperature. The results show that the new non-invasive probe using the thermal clearance method appears to be a useful device for measuring cutaneous microcirculation in anaesthetized humans, and responds more quickly than change in skin temperature, which is a delayed effect of skin blood flow change. Our results also show that the intensity of cutaneous vasodilatation induced by general anaesthesia did not relate to the vascular tone before anaesthesia.

  16. Relations between neuropsychological findings and lateral asymmetries of cerebral blood flow measured by SPECT in dementia of Alzheimer type

    Energy Technology Data Exchange (ETDEWEB)

    Yoshimura, Nahoko; Soma, Yoshiaki; Ootsuki, Mika [Takeda General Hospital, Aizu-Wakamatsu, Fukushima (Japan)

    1993-10-01

    We studied 16 right-handed patients clinically diagnosed as dementia of Alzheimer type (6 men, 10 women; aged 63-85, mean 72.8 years). The average duration of symptoms was 2.7 years. Dementia ranged from mild to moderately severe. None had clinical or laboratory evidence of cerebrovascular disease (Hachinski ischemic scores for all patients were 4 or below 4). All received the Wechsler Adult Intelligence Scale (WAIS), Mini-mental State Test (MMS) and Western Aphasia Battery (WAB, First Japanese edition, 1986). Regional cerebral blood flow (rCBF) was evaluated by single photon emission CT (SPECT) with {sup 123}I-N-isopropyl-p-iodoamphetamine ({sup 123}I-IMP), using the Matsuda`s quantitative method. Regional tracer uptake was measured in regions of interests (ROIs) over right and left frontal, temporal, parietal and occipital cortical regions; basal ganglia; and cerebellar hemispheres. The subjects were divided into three groups on the basis of lateral asymmetries in the temporal and parietal cortexes of rCBF (leftblood flow. Verbal IQ in patients with predominant hypoperfusion of left temporal and parietal lobe was significantly lower than other group, while performance IQ and WAB constructive scores were lower in those with right hemispheric hypoperfusion (p<0.05). We concluded that cerebral blood flow asymmetry by SPECT was related significantly to the deficit of language and constructive function in patients with dementia of Alzheimer type. Decreased rCBF in the left temporoparietal lobe was associated with language dysfunction, and that in the right hemisphere, with constructive dysfunction. (author).

  17. Relations between neuropsychological findings and lateral asymmetries of cerebral blood flow measured by SPECT in dementia of Alzheimer type

    International Nuclear Information System (INIS)

    We studied 16 right-handed patients clinically diagnosed as dementia of Alzheimer type (6 men, 10 women; aged 63-85, mean 72.8 years). The average duration of symptoms was 2.7 years. Dementia ranged from mild to moderately severe. None had clinical or laboratory evidence of cerebrovascular disease (Hachinski ischemic scores for all patients were 4 or below 4). All received the Wechsler Adult Intelligence Scale (WAIS), Mini-mental State Test (MMS) and Western Aphasia Battery (WAB, First Japanese edition, 1986). Regional cerebral blood flow (rCBF) was evaluated by single photon emission CT (SPECT) with 123I-N-isopropyl-p-iodoamphetamine (123I-IMP), using the Matsuda's quantitative method. Regional tracer uptake was measured in regions of interests (ROIs) over right and left frontal, temporal, parietal and occipital cortical regions; basal ganglia; and cerebellar hemispheres. The subjects were divided into three groups on the basis of lateral asymmetries in the temporal and parietal cortexes of rCBF (left< right, n=5; right< left, n=3; left=right, n=8). We decided that lateral asymmetry was present when rCBF for each ROI between left and right sides differs by more than 10%. General score (MMS, T-IQ) was not correlated with asymmetry of cerebral blood flow. Verbal IQ in patients with predominant hypoperfusion of left temporal and parietal lobe was significantly lower than other group, while performance IQ and WAB constructive scores were lower in those with right hemispheric hypoperfusion (p<0.05). We concluded that cerebral blood flow asymmetry by SPECT was related significantly to the deficit of language and constructive function in patients with dementia of Alzheimer type. Decreased rCBF in the left temporoparietal lobe was associated with language dysfunction, and that in the right hemisphere, with constructive dysfunction. (author)

  18. Evaluation of laser Doppler flowmetry for measuring coronary band and laminar microcirculatory blood flow in clinically normal horses.

    Science.gov (United States)

    Adair, H S; Goble, D O; Shires, G M; Sanders, W L

    1994-04-01

    Once daily for 3 days, laser Doppler flowmetry was used in 5 healthy, nonsedated adult horses to evaluate coronary band and laminar microcirculatory blood flow (MBF) in both forelimbs. The coronary band had significantly (P measurement period in any one site. Significant (P laminar MBF. On occlusion of the digital arteries at the level of the fetlock, marked decrease in coronary band and laminar MBF was observed. Twenty minutes after IV administration of acetylpromazine, marked increase in coronary band and laminar MBF was observed. The technique was easily performed in standing nonsedated horses, did not inflict discomfort, lacked complications, and measurements were repeatable. This technique provides an index of digital MBF, either intermittently or continuously, avoiding introduction of invasive variables associated with other techniques.

  19. Measurement of regional cerebral blood flow with H215O positron emission tomography during Matas test - report of three cases

    International Nuclear Information System (INIS)

    The authors carried out a Matas test with a regional cerebral blood flow (rCBF) study using H215O positron emission tomography (PET) for three cases of large internal carotid artery aneurysms. There is a likely correlation between the cerebral blood flow (CBF) reduction rate obtained by PET, and the mean stump pressure available from a conventional balloon occlusion test. The advantages of this noninvasive and quantitative method are presented in comparison with other methods. (author)

  20. Quantitative measurement of cerebral blood flow during hypothermia with a time-resolved near-infrared technique

    Science.gov (United States)

    Fazel Bakhsheshi, Mohammad; Diop, Mamadou; St Lawrence, Keith; Lee, Ting-Yim

    2012-02-01

    Hypothermia, in which the brain is cooled to 32-33 °C, has been shown to be neuroprotective for brain injury caused by hypoxia-ischemia, head trauma, or neonatal asphyxia. Neuroprotective effect of Hypothermia is partly due to suppression of brain metabolism and cerebral blood flow (CBF). The ability to measure CBF at the bedside provides a means of detecting, and thereby preventing, secondary ischemia during neuro intensive care before brain injury occurs. The purpose of the present study is to investigate the ability of a time-resolved near-infrared (TR-NIR) bolus-tracking method using indocyanine green as an intravascular flow tracer to measure CBF during cooling in a newborn animal model. For validation, CBF was independently measured by computed tomography (CT) perfusion. The results show a good agreement between CBF obtained with the two methods (R2 ~ 0.84, Δ ~ 5.84 ml. min -1.100 g -1, 32-38.5 °C), demonstrating the ability of the TR-NIR technique to non-invasively measure absolute CBF in-vivo during dynamic hypothermia. The TR-NIR technique reveals that CBF decreases from 54.3 +/- 5.4 ml. min -1.100 g -1, at normothermia (Tbrain of 38.5 °C), to 33.8 +/- 0.9 ml. min -1.100 g -1 at Tbrain of 32 °C during the hypothermia treatment.

  1. Comparison of uteroplacental blood flow in normal and pre-eclamptic patients measurement with technetium-99m and a computer-linked gamma camera

    International Nuclear Information System (INIS)

    Uteroplacental blood flow studies in preeclampsia are of special interest since the vascular changes reported in this disease might constitute a structural basis for a reduction of blood flow. Evidence has also been given for a decreased uteroplacental blood flow in preeclampsia. Among the various methods to estimate the maternal placental blood flow, the one most frequently reported in the literature during the last years has been the time activity analysis of short lived radiotracer such as technetium-99m or indium-113m injected intravenously. Only few studies with the above mentioned technique comparing normal and preeclampsia cases have been undertaken. In clinical practice we frequently experience difficuly in finding the optimal time to get the delivery in preeclampsia patients. The aim of this study was first to measure uteroplacental blood flow in preeclamptic pregnancies using a computer-linked gamma camera method for the time-activity analysis of technetium-99m and second to discuss the possibility of clinical application of these measurements for determination of fetal well-being and the timing of the delivery in these patients. Uteroplacental blood flow was measured from 13 preeclamptic patients and 19 pregnancies without any complication after 35 completed weeks of gestation from Jan. 1983 to Sep. 1983 at Obstetrics department of Hanyang University Hospital. (Author)

  2. Comparison of uteroplacental blood flow in normal and pre-eclamptic patients measurement with technetium-99m and a computer-linked gamma camera

    Energy Technology Data Exchange (ETDEWEB)

    Cho, S.H.; Moon, H.; Kim, D.S.; Cho, S.S.

    1985-05-01

    Uteroplacental blood flow studies in preeclampsia are of special interest since the vascular changes reported in this disease might constitute a structural basis for a reduction of blood flow. Evidence has also been given for a decreased uteroplacental blood flow in preeclampsia. Among the various methods to estimate the maternal placental blood flow, the one most frequently reported in the literature during the last years has been the time activity analysis of short lived radiotracer such as technetium-99m or indium-113m injected intravenously. Only few studies with the above mentioned technique comparing normal and preeclampsia cases have been undertaken. In clinical practice we frequently experience difficuly in finding the optimal time to get the delivery in preeclampsia patients. The aim of this study was first to measure uteroplacental blood flow in preeclamptic pregnancies using a computer-linked gamma camera method for the time-activity analysis of technetium-99m and second to discuss the possibility of clinical application of these measurements for determination of fetal well-being and the timing of the delivery in these patients. Uteroplacental blood flow was measured from 13 preeclamptic patients and 19 pregnancies without any complication after 35 completed weeks of gestation from Jan. 1983 to Sep. 1983 at Obstetrics department of Hanyang University Hospital. (Author).

  3. New optical sensing technique of tissue viability and blood flow based on nanophotonic iterative multi-plane reflectance measurements

    Directory of Open Access Journals (Sweden)

    Yariv I

    2016-10-01

    Full Text Available Inbar Yariv,1 Menashe Haddad,2,3 Hamootal Duadi,1 Menachem Motiei,1 Dror Fixler1 1Faculty of Engineering and the Institute of Nanotechnology and Advanced Materials, Bar Ilan University, Ramat Gan, Israel; 2Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel; 3Mayanei Hayeshua Medical Center, Benei Brak, Israel Abstract: Physiological substances pose a challenge for researchers since their optical properties change constantly according to their physiological state. Examination of those substances noninvasively can be achieved by different optical methods with high sensitivity. Our research suggests the application of a novel noninvasive nanophotonics technique, ie, iterative multi-plane optical property extraction (IMOPE based on reflectance measurements, for tissue viability examination and gold nanorods (GNRs and blood flow detection. The IMOPE model combines an experimental setup designed for recording light intensity images with the multi-plane iterative Gerchberg-Saxton algorithm for reconstructing the reemitted light phase and calculating its standard deviation (STD. Changes in tissue composition affect its optical properties which results in changes in the light phase that can be measured by its STD. We have demonstrated this new concept of correlating the light phase STD and the optical properties of a substance, using transmission measurements only. This paper presents, for the first time, reflectance based IMOPE tissue viability examination, producing a decrease in the computed STD for older tissues, as well as investigating their organic material absorption capability. Finally, differentiation of the femoral vein from adjacent tissues using GNRs and the detection of their presence within blood circulation and tissues are also presented with high sensitivity (better than computed tomography to low quantities of GNRs (<3 mg. Keywords: Gerchberg-Saxton, optical properties, gold nanorods, blood vessel, tissue viability

  4. Dose reduction in dynamic perfusion CT of the brain: effects of the scan frequency on measurements of cerebral blood flow, cerebral blood volume, and mean transit time

    Energy Technology Data Exchange (ETDEWEB)

    Wiesmann, Martin [University of Munich, Department of Neuroradiology, Muenchen (Germany); Klinikum der Universitaet Muenchen - Grosshadern, Abteilung fuer Neuroradiologie, Muenchen (Germany); Berg, Scott; Stoeckelhuber, B.M. [University of Luebeck, Department of Radiology, Luebeck (Germany); Bohner, G.; Klingebiel, R. [University Medicine Berlin, Department of Neuroradiology, Charite, Berlin (Germany); Schoepf, V.; Yousry, I.; Linn, J. [University of Munich, Department of Neuroradiology, Muenchen (Germany); Missler, U. [Evangelisches Krankenhaus Duisburg-Nord, Department of Neuroradiology, Duisburg (Germany)

    2008-12-15

    The influence of the frequency of computed tomography (CT) image acquistion on the diagnostic quality of dynamic perfusion CT (PCT) studies of the brain was investigated. Eight patients with clinically suspected acute ischemia of one hemisphere underwent PCT, performed on average 3.4 h after the onset of symptoms. Sixty consecutive images per slice were obtained with individual CT images obtained at a temporal resolution of two images per second. Eight additional data sets were reconstructed with temporal resolutions ranging from one image per second to one image per 5 s. Cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) measurements were performed in identical regions of interest. Two neuroradiologists evaluated the PCT images visually to identify areas of abnormal perfusion. Perfusion images created up to a temporal resolution of one image per 3 s were rated to be diagnostically equal to the original data. Even at one image per 4 s, all areas of infarction were identified. Quantitative differences of CBF, CBV and MTT measurements were {<=}10% up to one image per 3 s. For PCT of the brain, temporal resolution can be reduced to one image per 3 s without significant compromise in image quality. This significantly reduces the radiation dose of the patient. (orig.)

  5. Blood flow autoregulation in pedicled flaps

    DEFF Research Database (Denmark)

    Bonde, Christian T; Holstein-Rathlou, Niels-Henrik; Elberg, Jens J

    2009-01-01

    INTRODUCTION: Clinical work on the blood perfusion in skin and muscle flaps has suggested that some degree of blood flow autoregulation exists in such flaps. An autoregulatory mechanism would enable the flap to protect itself from changes in the perfusion pressure. The purpose of the present study...... was to evaluate if, and to what extent, a tissue flap could compensate a reduction in blood flow due to an acute constriction of the feed artery. Further, we wanted to examine the possible role of smooth muscle L-type calcium channels in the autoregulatory mechanism by pharmacological intervention with the L......-type calcium channel blocker nimodipine and the vasodilator papaverine. MATERIAL AND METHODS: Pedicled flaps were raised in pigs. Flow in the pedicle was reduced by constriction of the feed artery (n=34). A transit time flow probe measured the effect on blood flow continuously. Following this, three different...

  6. MR velocity mapping measurement of renal artery blood flow in patients with impaired kidney function

    DEFF Research Database (Denmark)

    Cortsen, M; Petersen, L.J.; Stahlberg, F;

    1996-01-01

    . MR velocity mapping was performed in both renal arteries using an ECG-triggered gradient echo pulse sequence previously validated in normal volunteers. Effective renal plasma flow was calculated from the clearance rate of PAH during constant infusion and the split of renal function was evaluated by...

  7. Blood flow in the choriocapillaris

    OpenAIRE

    Zouache, M. A.; Eames, I; Luthert, P J

    2015-01-01

    The choriocapillaris is a capillary bed located in a thin layer adjacent to the outer retina and is part of the oxygen delivery system to the photoreceptors of the eye. The blood flow is approximately planar and is serviced by microvessels, which join the choriocapillaris through inlets perpendicular to its plane. Capillaries are densely organised and separated by avascular septal posts, which direct the blood flow. The capillary bed is composed of a juxtaposition of tessellating vascular uni...

  8. Computer-aided method for automated selection of optimal imaging plane for measurement of total cerebral blood flow by MRI

    Science.gov (United States)

    Teng, Pang-yu; Bagci, Ahmet Murat; Alperin, Noam

    2009-02-01

    A computer-aided method for finding an optimal imaging plane for simultaneous measurement of the arterial blood inflow through the 4 vessels leading blood to the brain by phase contrast magnetic resonance imaging is presented. The method performance is compared with manual selection by two observers. The skeletons of the 4 vessels for which centerlines are generated are first extracted. Then, a global direction of the relatively less curved internal carotid arteries is calculated to determine the main flow direction. This is then used as a reference direction to identify segments of the vertebral arteries that strongly deviates from the main flow direction. These segments are then used to identify anatomical landmarks for improved consistency of the imaging plane selection. An optimal imaging plane is then identified by finding a plane with the smallest error value, which is defined as the sum of the angles between the plane's normal and the vessel centerline's direction at the location of the intersections. Error values obtained using the automated and the manual methods were then compared using 9 magnetic resonance angiography (MRA) data sets. The automated method considerably outperformed the manual selection. The mean error value with the automated method was significantly lower than the manual method, 0.09+/-0.07 vs. 0.53+/-0.45, respectively (p<.0001, Student's t-test). Reproducibility of repeated measurements was analyzed using Bland and Altman's test, the mean 95% limits of agreements for the automated and manual method were 0.01~0.02 and 0.43~0.55 respectively.

  9. In-vitro validation of a novel model-based approach to the measurement of arterial blood flow waveforms from dynamic digital x-ray images

    Science.gov (United States)

    Rhode, Kawal; Lambrou, Tryphon; Seifalian, Alexander M.; Hawkes, David J.

    2002-04-01

    We have developed a waveform shape model-based algorithm for the extraction of blood flow from dynamic arterial x-ray angiographic images. We have carried out in-vitro validation of this technique. A pulsatile physiological blood flow circuit was constructed using an anthropomorphic cerebral vascular phantom to simulate the cerebral arterial circulation with whole blood as the fluid. Instantaneous recording of flow from an electromagnetic flow meter (EMF) provided the gold standard measurement. Biplane dynamic digital x-ray images of the vascular phantom with injection of contrast medium were acquired at 25 fps using a PC frame capture card with calibration using a Perspex cube. Principal component analysis was used to construct a shape model by collecting 434 flow waveforms from the EMF under varying flow conditions. Blood flow waveforms were calculated from the angiographic data by using our previous concentration-distance curve matching (ORG) algorithm and by using the new model-based (MB) algorithm. Both instantaneous and mean flow values calculated using the MB algorithm showed greater correlation, less bias, and lower variability than those calculated using the ORG algorithm when compared to the EMF values. We have successfully demonstrated that use of a priori waveform shape information can improve flow measurements from dynamic x-ray angiograms.

  10. Measurement of cerebral blood flow the blood sampling method using {sup 99m}Tc-ECD. Simultaneous scintigram scanning of arterial blood samples and the brain with a gamma camera

    Energy Technology Data Exchange (ETDEWEB)

    Hachiya, Takenori; Inugami, Atsushi [Rehabilitation Center for Physically Disabled Persons and Medical Center for Mental Health-Akita, Kyowa (Japan); Iida, Hidehiro; Mizuta, Yoshihiko; Kawakami, Takeshi; Inoue, Minoru

    1999-01-01

    To measure regional cerebral blood flow (rCBF) by blood sampling using {sup 99m}Tc-ECD we devised a method of measuring the radioactive concentration in arterial blood sample with a gamma camera. In this method the head and a blood sample are placed within the same visual field to record the SPECT data of both specimens simultaneously. The results of an evaluation of the counting rate performance, applying the 30 hours decaying method using {sup 99m}Tc solution showed that this method is not comparable to the well-type scintillation counter and in clinical cases the active concentration in arterial blood sample remained well within the dynamic range. In addition, examination of the influence of scattered radiation from the brain by the dilution method showed that it was negligible at a distance of more than 7.5 cm between the brain and the arterial blood sample. In the present study we placed a head-shaped phantom next to the sample. The results of the examinations suggested that this method is suitable for clinical application, and because it does not require a well-type scintillation counter, it is expected to find wide application. (author)

  11. Intracranial blood flow measured with single photon emission computer tomography (SPECT) during transient -6 degrees head-down tilt.

    Science.gov (United States)

    Satake, H; Konishi, T; Kawashima, T; Matsunami, K; Uno, T; Imai, S; Yamada, H; Hirakawa, C

    1994-02-01

    Regional cerebral blood flow (CBF) during a transient head-down tilt of -6 degrees (-6 degrees HDT) was measured with single photon emission computer tomography (SPECT). CBF was measured and averaged for both sides of the brain areas; e.g., the bilateral anterior cerebral artery (bACA) area, the middle cerebral artery (bMCA) area, the posterior cerebral artery (bPCA) area, bilateral basal ganglia, and the cerebellum. Among these areas, a significant increase in CBF was observed in the basal ganglia and the cerebellum during -6 degrees HDT compared to pre-HDT. When CBF was measured separately in the left or right brain area, these significances disappeared, although a trend of increase or decrease was still observable. A trend of increase was observed in the left anterior cerebral artery (IACA) area, the right middle cerebral artery (rMCA) area, the right posterior cerebral artery (rPCA) area, the left and right basal ganglia, and the cerebellum. In rACA, IMCA and IPCA areas, a slight decrease in CBF was observed. At the same time, cardiac parameters were measured. Heart rate (HR), stroke volume (SV) and cardiac output (CO) did not change significantly, although SV slightly increased and HR slightly decreased during -6 degrees HDT.

  12. Molecular versus particulate deposition markers for blood flow measurement in the musculo-skeletal system. 131Iodo-DesMethyl-Imipramine

    International Nuclear Information System (INIS)

    The aims of the experiments were to develop and validate a porcine isolated blood perfused myocutaneous flap and tibia model with preserved venous outflow. The stability of the models was tested and washout of microspheres and IDMI was measured. IDMI and microsphere based tissue blood flow measurements were compared after central intracardiac injection into the intact animal. Three experimental series were necessary to develop and validate the models. The organs were perfused with arterial blood by a pulsatile pump and submerged into a tissue bath. All outflow from the models were collected. One experiment was necessary to validate the rectus abdominis myocutaneous flap. In three experiments an isolated tibia with preserved venous outflow was developed and validated. Normal flow rate/perfusion pressure relations were reproduced after periods of supra-normal and sub-normal perfusion pressure in the two models. A response to endothelially mediated vasodilation with bradykinin was demonstrated after nine hours of artificial perfusion in the tibia model. IDMI did not influence the local hemodynamics during infusion, whereas microspheres elicited a transitory increase in the perfusion pressure after local injection. IDMI and microsphere based blood flow measurements and recirculation were compared in the in-situ musculo-skeletal tissue corresponding to the two models after central injection of the markers. Recirculation of IDMI was greater (8(1)%) than that of microspheres (2(0)%) after 18 minutes. Microspheres tended to measure higher blood flow values than IDMI at high flow rates and vice versa at low flow values. The 131Iodo-DesMethyl-Imipramine (IDMI) method is not generally applicable as a deposition marker for blood flow measurement in the musculo-skeletal system. (EHS)

  13. Measurement of regional cerebral blood flow with single photon emission computed tomography in patients with aphasia

    International Nuclear Information System (INIS)

    5 cases are demonstrated of patients with aphasia whose brain perfusion as measured regionally by SPECT using 133Xe was correlated to the lesions seen in the CT study. Perfusion reductions exceeded the CT visible lesions, such as, that in cortical lesions perfusion in the region of basal ganglia is diminished and vice versa. The findings are discussed in relation to recent work on brain perfusion and metabolism. (orig.)

  14. Tracer-kinetic models for measuring cerebral blood flow using externally detected radiotracers

    International Nuclear Information System (INIS)

    All tracer-kinetic models currently employed with positron-emission tomography (PET) are based on compartmental assumptions. Our first indication that a compartmental model might suffer from severe limitations in certain circumstances when used with PET occurred when we implemented the Kety tissue-autoradiography technique for measuring CBF and observed that the resulting CBF estimates, rather than remaining constant (to within predictable statistical uncertainty) as expected, fell with increasing scan duration T when T greater than 1 min. After ruling out other explanations, we concluded that a one-compartment model does not possess sufficient realism for adequately describing the movement of labeled water in brain. This article recounts our search for more realistic substitute models. We give our derivations and results for the residue-detection impulse responses for unit capillary-tissue systems of our two candidate distributed-parameter models. In a sequence of trials beginning with the simplest, we tested four progressively more detailed candidate models against data from appropriate residue-detection experiments. In these, we generated high-temporal-resolution counting-rate data reflecting the history of radiolabeled-water uptake and washout in the brains of rhesus monkeys. We describe our treatment of the data to yield model-independent empirical values of CBF and of other parameters. By substituting these into our trial-model functions, we were able to make direct comparisons of the model predictions with the experimental dynamic counting-rate histories, confirming that our reservations concerning the one-compartment model were well founded and obliging us to reject two others. We conclude that a two-barrier distributed-parameter model has the potential of serving as a substitute for the Kety model in PET measurements of CBF in patients, especially when scan durations for T greater than 1 min are desired

  15. Differences in lateral hemispheric asymmetries of cerebral blood flow measured by SPECT in dementia of Alzheimer type

    Energy Technology Data Exchange (ETDEWEB)

    Yoshimura, Nahoko (Niigata Univ. (Japan). School of Medicine)

    1993-12-01

    We studied 21 right-handed patients clinically diagnosed as dementia of Alzheimer type (8 men, 13 women; aged 53-85, mean 71.1 years). The average duration of symptoms was 2.7 years. Dementia ranged from mild to moderately severe. None had clinical or laboratory evidence of cerebro-vascular disease (Hachinski ischemic scores for all patients were 4 or below). All received the Wechsler Adult Intelligence Scale (WAIS), Mini-mental State Test (MMS) and Western Aphasia Battery (WAB, First Japanese edition, 1986). Regional cerebral blood flow was evaluated by single photon emission CT (SPECT) with [sup 123]I-N-isopropyl-p-iodoamphetamine ([sup 123]I-IMP), using the Matsuda's quantitative method. The subjects were divided into three groups on the basis of right-left hemispheric asymmetry of cerebral blood flow (leftblood flow. Verbal IQ in patients with predominant hypoperfusion of left temporal and parietal lobe were significantly lower than in other groups, while performance IQ and WAB constructive scores were lower in those with right hemispheric hypoperfusion (p<0.05). We concluded that cerebral blood flow asymmetry detected by SPECT was related significantly to the deficit of language and constructive function in patients with dementia of Alzheimer type. (author).

  16. An implantable blood pressure and flow transmitter.

    Science.gov (United States)

    Rader, R. D.; Meehan, J. P.; Henriksen, J. K. C.

    1973-01-01

    A miniature totally implantable FM/FM telemetry system has been developed to simultaneously measure blood pressure and blood flow, thus providing an appreciation of the hemodynamics of the circulation to the entire body or to a particular organ. Developed for work with animal subjects, the telemetry system's transmission time is controlled by an RF signal that permits an operating life of several months. Pressure is detected by a miniature intravascular transducer and flow is detected by an extravascular interferometric ultrasonic technique. Both pressure and flow are calibrated prior to implanting. The pressure calibration can be checked after the implanting by cannulation; flow calibration can be verified only at the end of the experiment by determining the voltage output from the implanted sensing system as a function of several measured flow rates. The utility of this device has been established by its use in investigating canine renal circulation during exercise, emotional encounters, administration of drugs, and application of accelerative forces.

  17. The effect of black tea and caffeine on regional cerebral blood flow measured with arterial spin labeling

    Science.gov (United States)

    Vidyasagar, Rishma; Greyling, Arno; Draijer, Richard; Corfield, Douglas R; Parkes, Laura M

    2013-01-01

    Black tea consumption has been shown to improve peripheral vascular function. Its effect on brain vasculature is unknown, though tea contains small amounts of caffeine, a psychoactive substance known to influence cerebral blood flow (CBF). We investigated the effects on CBF due to the intake of tea components in 20 healthy men in a double-blinded, randomized, placebo-controlled study. On separate days, subjects received a single dose of 184 mg caffeine (equivalent to one strong espresso coffee), 2,820 mg black tea solids containing 184 mg caffeine (equivalent to 6 cups of tea), 2,820 mg decaffeinated black tea solids, or placebo. The CBF and cerebrovascular reactivity (CVR) to hypercapnia were measured with arterial spin labeled magnetic resonance imaging (MRI) before and 2 hours after administration. We found a significant global reduction with caffeine (20%) and tea (21%) in gray matter CBF, with no effect of decaffeinated tea, suggesting that only caffeine influences CBF acutely. Voxelwise analysis revealed the effect of caffeine to be regionally specific. None of the interventions had an effect on CVR. Additional research is required to conclude on the physiologic relevance of these findings and the chronic effects of caffeine and tea intake on CBF. PMID:23486295

  18. The effect of black tea and caffeine on regional cerebral blood flow measured with arterial spin labeling.

    Science.gov (United States)

    Vidyasagar, Rishma; Greyling, Arno; Draijer, Richard; Corfield, Douglas R; Parkes, Laura M

    2013-06-01

    Black tea consumption has been shown to improve peripheral vascular function. Its effect on brain vasculature is unknown, though tea contains small amounts of caffeine, a psychoactive substance known to influence cerebral blood flow (CBF). We investigated the effects on CBF due to the intake of tea components in 20 healthy men in a double-blinded, randomized, placebo-controlled study. On separate days, subjects received a single dose of 184 mg caffeine (equivalent to one strong espresso coffee), 2,820 mg black tea solids containing 184 mg caffeine (equivalent to 6 cups of tea), 2,820 mg decaffeinated black tea solids, or placebo. The CBF and cerebrovascular reactivity (CVR) to hypercapnia were measured with arterial spin labeled magnetic resonance imaging (MRI) before and 2 hours after administration. We found a significant global reduction with caffeine (20%) and tea (21%) in gray matter CBF, with no effect of decaffeinated tea, suggesting that only caffeine influences CBF acutely. Voxelwise analysis revealed the effect of caffeine to be regionally specific. None of the interventions had an effect on CVR. Additional research is required to conclude on the physiologic relevance of these findings and the chronic effects of caffeine and tea intake on CBF.

  19. Cerebral blood-flow tomography

    DEFF Research Database (Denmark)

    Lassen, N A; Henriksen, L; Holm, S;

    1983-01-01

    Tomographic maps of local cerebral blood flow (CBF) were obtained with xenon-133 and with isopropyl-amphetamine-iodine-123 (IMP) in 11 subjects: one normal, two tumor cases, and eight cerebrovascular cases. A highly sensitive four-face, rapidly rotating, single-photon emission tomograph was used...

  20. Studies on 133Xe wash-out from human skin: quantitative measurements of blood flow in normal and corticosteroid-treated skin.

    Science.gov (United States)

    Kristensen, J K; Wadskov, S

    1977-04-01

    Blood flow was measured by the 133Xe technique in normal and corticosteroid-treated skin. Epicutaneous and intracutaneous methods of tracer application were compared in normal skin. The two labeling methods were equally suitable for measuring cutaneous blood flow provided calculations in both cases were based on a biexponential resolution of the wash-out curve in its cutaneous and subcutaneous components and provided the traumatic hyperemia phase was considered, when intracutaneous application of the tracer was used. Results were invalidated if calculations were based on initial slope of the wash-out curves.Topical application of beta-methasone valerate in a reduction in cutaneous blood flow as measured by the intracutaneous technique with curve resolution, whereas no effect could be demonstrated when calculations were based on the initial slopes of the curves. The 133Xe technique is a simple and reliable method for measuring cutaneous blood flow, which might prove useful in estimations of penetration ability and potency of topical corticosteroids.

  1. Validation of PSF-based 3D reconstruction for myocardial blood flow measurements with Rb-82 PET

    DEFF Research Database (Denmark)

    Tolbod, Lars Poulsen; Christensen, Nana Louise; Møller, Lone W.;

    is not well validated and problems with both edge-effects and unphysical contrast-recovery have been reported.1 In this study, we compare myocardial blood flow (MBF) and coronary flow reserve (CFR) obtained using GEs implementation of PSF, SharpIR, with the conventional method for reconstruction of dynamic...... images, filtered backprojection (FBP). Furthermore, since myocardial segmentation might be affected by image quality, two different approaches to segmentation implemented in standard software (Carimas (Turku PET Centre) and QPET (Cedar Sinai)) are utilized. Method:14 dynamic rest-stress Rb-82 patient...

  2. Focal cerebral ischemia measured by the intra-arterial 133xenon method. Limitations of 2-dimensional blood flow measurements

    DEFF Research Database (Denmark)

    Skyhøj Olsen, T; Larsen, B; Bech Skriver, E;

    1981-01-01

    The limitations of 2-dimensional isotope techniques in the study of focal cerebral ischemia were investigated using the intra-carotid 133 xenon injection method and a 254 multidetector scintillation camera. To make sure that the detectors "look" directly on infarcted areas, only patients with inf......The limitations of 2-dimensional isotope techniques in the study of focal cerebral ischemia were investigated using the intra-carotid 133 xenon injection method and a 254 multidetector scintillation camera. To make sure that the detectors "look" directly on infarcted areas, only patients...... with infarcts involving cortical surface structures were included in the study. Eleven such patients were found among 43 consecutive patients with completed stroke, all investigated with CT-scan. The blood supply to the infarcted areas was evaluated using 3 different approaches: 1) The first minute washout...... ischemic lesions. The method should be limited to the qualitative demonstration of the ischemic lesions for which it is fully reliable....

  3. Assessment of Uterine Receptivity by Endometrial and Subendometrial Blood Flows Measured by Vaginal Color Doppler Ultrasound in Women Undergoing IVF Treatment

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Obiective To evaluate endometrial and Subendometrial blood flows measured by vaginal color Doppler ultrasound as a predicator of endometrial receptivity in women undergoing IVF treatment.Methods A total of 119 infertile patients undergoing the first IVF/ICSI-ET cycle were recruited.Three groups were divided according to a color Doppler ultrasound examination performed on the day of hCG injection.Group A,endometrial and subendometrial blood flows were 2 branches and below,group B,endometrial and subendometrial blood flows were between 3 and 4 branches;group C, endometrial and subendometrial blood flows were 5 branches and above.Patients were transferred 1-3 embryos each.Demographic data,ovarian responses.endometrial thickness,PI,RI,development of embryo and IVF result among groups were compared.Results Demographic data,ovarian responses,endometrial thickness,PI,RI and development of embryo among groups have no significant difference.The pregnancy rate of group A was significantly lower than that of group B(P<0.05) and group C(P<0.01).The implantation rate of group A was significantly lower than than of group C (P<0.01).There was no significant difference of the rate of pregnancy and implantation between group B and group C (P>0.05).Conclusion Endometrial and subendometrial blood flows measured by vaginal color Doppler ultrasound is a good predicator of pregnancy during IVF treatment.A good endometrial and subendometrial blood flows is benefit for the result of IVF.

  4. The effect of black tea and caffeine on regional cerebral blood flow measured with arterial spin labeling

    OpenAIRE

    Vidyasagar, Rishma; Greyling, Arno; Draijer, Richard; Corfield, Douglas R; Parkes, Laura M.

    2013-01-01

    Black tea consumption has been shown to improve peripheral vascular function. Its effect on brain vasculature is unknown, though tea contains small amounts of caffeine, a psychoactive substance known to influence cerebral blood flow (CBF). We investigated the effects on CBF due to the intake of tea components in 20 healthy men in a double-blinded, randomized, placebo-controlled study. On separate days, subjects received a single dose of 184 mg caffeine (equivalent to one strong espresso coffe...

  5. Error analysis of tumor blood flow measurement using dynamic contrast-enhanced data and model-independent deconvolution analysis

    International Nuclear Information System (INIS)

    We performed error analysis of tumor blood flow (TBF) measurement using dynamic contrast-enhanced data and model-independent deconvolution analysis, based on computer simulations. For analysis, we generated a time-dependent concentration of the contrast agent in the volume of interest (VOI) from the arterial input function (AIF) consisting of gamma-variate functions using an adiabatic approximation to the tissue homogeneity model under various plasma flow (Fp), mean capillary transit time (Tc), permeability-surface area product (PS) and signal-to-noise ratio (SNR) values. Deconvolution analyses based on truncated singular value decomposition with a fixed threshold value (TSVD-F), with an adaptive threshold value (TSVD-A) and with the threshold value determined by generalized cross validation (TSVD-G) were used to estimate Fp values from the simulated concentration-time curves in the VOI and AIF. First, we investigated the relationship between the optimal threshold value and SNR in TSVD-F, and then derived the equation describing the relationship between the threshold value and SNR for TSVD-A. Second, we investigated the dependences of the estimated Fp values on Tc, PS, the total duration for data acquisition and the shape of AIF. Although TSVD-F with a threshold value of 0.025, TSVD-A with the threshold value determined by the equation derived in this study and TSVD-G could estimate the Fp values in a similar manner, the standard deviation of the estimates was the smallest and largest for TSVD-A and TSVD-G, respectively. PS did not largely affect the estimates, while Tc did in all methods. Increasing the total duration significantly improved the variations in the estimates in all methods. TSVD-G was most sensitive to the shape of AIF, especially when the total duration was short. In conclusion, this study will be useful for understanding the reliability and limitation of model-independent deconvolution analysis when applied to TBF measurement using an extravascular

  6. Cerebral blood flow in acute mountain sickness

    DEFF Research Database (Denmark)

    Jensen, J B; Wright, Anne; Lassen, N A;

    1990-01-01

    Changes in cerebral blood flow (CBF) were measured using the radioactive xenon technique and were related to the development of acute mountain sickness (AMS). In 12 subjects, ascending from 150 to 3,475 m, CBF was 24% increased at 24 h [45.1 to 55.9 initial slope index (ISI) units] and 4% increased...

  7. Cerebral blood flow tomography with xenon-133

    DEFF Research Database (Denmark)

    Lassen, N A

    1985-01-01

    Cerebral blood flow (CBF) can be measured tomographically by inhalation of Xenon-133. The calculation is based on taking a sequence of tomograms during the wash-in and wash-out phase of the tracer. Due to the dynamic nature of the process, a highly sensitive and fast moving single photon emission...

  8. Progress and Clinical Application of PET Cerebral Blood Flow Measurement Method%PET脑血流量测量方法和临床应用进展

    Institute of Scientific and Technical Information of China (English)

    徐浩; 赵周社; 李红; 凌雪英; 唐勇进; 弓健; 郭斌

    2015-01-01

    Cerebral blood flow measurement for cerebrovascular disease,brain tumor diagnosis and therapeutic effect evaluation has important clinical value.PET is based on positron tracer technique for noninvasive,accurate measurement of cerebral blood flow is increasingly widely used in clinical.PET measurement of cerebral blood flow in accordance with the methods and use of positron tracer is different,and the measurement methods are divided into equilibrium method,autoradiographic method and dynamic method.15O-H2O tracer PET measurement of cerebral blood flow is considered to be the "gold standard" method of cerebral blood flow measurement.As the PET equipment resolution improving,the new image reconstruction method using PET and MRI image fusion technology continues to mature,the 18F-FDG first pass image using derivative arterial input function (IDAIF) replace artery blood sample accurate measurement of cerebral blood volume method has been paid attention to,may gradually replace the high cost of 15O-H2O measurement of cerebral blood flow.PET is noninvasive,convenient and accurate measurement of cerebral blood flow in clinical use will greatly promote cerebral vascular disease,brain tumor and brain degenerative disease early diagnosis,differential diagnosis and personalized medicine.This paper introduced PET cerebral blood flow measurement principle,methods and progress in clinical application.%脑血流量测量对于脑血管疾病、脑肿瘤诊断和疗效评估具有重要的临床价值.PET是基于正电子示剂技术无创性、精确测量脑血流量的方法,正日益广泛地应用于临床.按照PET测量脑血流量的方法和使用的正电子示踪剂不同,其测量方法分为平衡法、放射自显影法和动力学方法三种.18O-H2O示踪剂PET测量脑血流量被认为测量脑血流方法的“金标准”.随着PET设备分辨率提高、新的图像重建方法使用和PET与MRI图像融合技术不断成熟,18F-FDG首次通过、采用图

  9. Blood flow in healed and inflamed periodontal tissues of dogs

    Energy Technology Data Exchange (ETDEWEB)

    Hock, J.M.; Kim, S.

    1987-01-01

    The objectives of this study were to determine if increased blood flow associated with gingivitis would decrease following resolution of gingival inflammation in dogs with periodontitis; if increased blood flow in inflamed gingiva was associated with changes in the blood flow of alveolar bone, and if blood flow in gingiva and alveolar bone increased if periodontitis was reactivated by ligating teeth. Regional blood flow was measured in dogs with pre-existing periodontitis, using radioisotope-labelled, plastic microspheres. In the first experiment on 4 adult Beagle dogs, teeth in the left jaws were treated to resolve the periodontitis, while teeth in the right jaws were not treated. Gingival and bone blood flow were measured after 12 wk. Blood flow was significantly (p<0.05) lower in non-inflamed healed gingiva (32.1 +- 2.7 ml/min/100 g) than in inflamed gingiva (46.1 +- 5.3 ml/min/100 g). No differences in the blood flow of the alveolar bone underlying inflamed or non-inflamed gingiva were present. In the second experiment, the right mandibular teeth of 5 dogs were treated to resolve periodontitis while teeth in the other quadrants were ligated for 4, 10 or 12 wk. The duration of ligation did not alter blood flow. Gingival blood flow around ligated maxillary and mandibular teeth was comparable and approximately 54% higher than around non-ligated teeth (p<0.03). The difference in blood flow between gingiva with G.I.>1 and gingiva with G.I.<2 was significant (p<0.04). Blood flow in bone was not altered by changes in the inflammatory status of the overlying gingiva. The findings suggest that changes in blood flow associated with inflammation are reversible and that blood flow alveolar bone is regulated independently of gingival blood flow.

  10. Subcutaneous blood flow during insulin-induced hypoglycaemia

    DEFF Research Database (Denmark)

    Hilsted, J; Madsbad, S; Sestoft, L

    1982-01-01

    Subcutaneous blood flow was measured preceding insulin-induced hypoglycaemia, at the onset of hypoglycaemic symptoms and 2 h later in juvenile diabetics with and without autonomic neuropathy and in normal males. In all groups subcutaneous blood flow decreased at the onset of hypoglycaemic symptoms...... compared with pre-hypoglycaemic flow. Two hours after onset of hypoglycaemic symptoms, subcutaneous blood flow was still significantly decreased compared with pre-hypoglycaemic flow. In normal subjects local nerve blockade had no effect on blood flow changes during hypoglycaemia, whereas local alpha...

  11. Blood flow in healed and inflamed periodontal tissues of dogs

    International Nuclear Information System (INIS)

    The objectives of this study were to determine if increased blood flow associated with gingivitis would decrease following resolution of gingival inflammation in dogs with periodontitis; if increased blood flow in inflamed gingiva was associated with changes in the blood flow of alveolar bone, and if blood flow in gingiva and alveolar bone increased if periodontitis was reactivated by ligating teeth. Regional blood flow was measured in dogs with pre-existing periodontitis, using radioisotope-labelled, plastic microspheres. In the first experiment on 4 adult Beagle dogs, teeth in the left jaws were treated to resolve the periodontitis, while teeth in the right jaws were not treated. Gingival and bone blood flow were measured after 12 wk. Blood flow was significantly (p1 and gingiva with G.I.<2 was significant (p<0.04). Blood flow in bone was not altered by changes in the inflammatory status of the overlying gingiva. The findings suggest that changes in blood flow associated with inflammation are reversible and that blood flow alveolar bone is regulated independently of gingival blood flow. (author)

  12. Relative pressure estimation from velocity measurements in blood flows: state-of-the-art and new approaches

    OpenAIRE

    Bertoglio, Cristobal; Núñez, Rodolfo; Galarce, Felipe; Nordsletten, David; Osses, Axel

    2016-01-01

    The pressure gradient across stenotic blood vessels is an important clinical index for diagnosis of the pathological severity of the cardiovascular disease. While the clinical gold standard for its measurement is invasive catheterization, Phase-Contrast MR-imaging has emerged as a promising tool for enabling a non-invasive quantification of the relative pressures, by linking the (highly spatially resolved) velocity measurements with the relative pressure via the Navier-Stokes equations. In th...

  13. Blood flow measurement of portal vein with fast cine phase contrast MR imaging under breath-holding

    International Nuclear Information System (INIS)

    Flow measurements of the right portal vein were performed in seven healthy volunteers with the segmented k-space fast gradient-echo phase-contrast (fcard-PC) sequence under breath-holding. The mean velocity and the flow rate of the right portal vein at maximal expiration, 14.3±4.4 cm/sec and 457±218 ml/min, were significantly greater (p<0.01) than those at maximal inspiration: 11.8±3.8 cm/sec (mean±SD) and 364±191 ml/min, respectively. Fcard-PC enabled flow measurements to be obtained under breath-holding. Using this technique, we demonstrated portal venous flow changes according to respiratory phase. (author)

  14. Blood flow measurement of portal vein with fast cine phase contrast MR imaging under breath-holding

    Energy Technology Data Exchange (ETDEWEB)

    Inaba, Fumitaka; Murakami, Takamichi; Sakurai, Kosuke; Tsuda, Kyo; Kim, Tonsoku; Tanaka, Hisashi; Kashiwagi, Nobuo; Nakamura, Hironobu [Osaka Univ. (Japan). Faculty of Medicine; Harada, Koshi

    1996-03-01

    Flow measurements of the right portal vein were performed in seven healthy volunteers with the segmented k-space fast gradient-echo phase-contrast (fcard-PC) sequence under breath-holding. The mean velocity and the flow rate of the right portal vein at maximal expiration, 14.3{+-}4.4 cm/sec and 457{+-}218 ml/min, were significantly greater (p<0.01) than those at maximal inspiration: 11.8{+-}3.8 cm/sec (mean{+-}SD) and 364{+-}191 ml/min, respectively. Fcard-PC enabled flow measurements to be obtained under breath-holding. Using this technique, we demonstrated portal venous flow changes according to respiratory phase. (author).

  15. [Pulmonary blood flow measurement using magnetic resonance imaging (MRI) without contrast medium;comparison of phase contrast MRI and perfusion-ventilation scintigraphy].

    Science.gov (United States)

    Yatsuyanagi, Eiji; Sato, Kazuhiro; Kikuchi, Keisuke; Saito, Hirotsugu

    2014-02-01

    To define the accuracy of pulmonary arterial blood flow (PA-flow) measured by phase contrast magnetic resonance imaging (PC-MRI), we compared the PA-flow data of PC-MRI with the data of perfusion-ventilation lung scintigraphy. Eighteen patients who preoperatively underwent PA-flow measurement using PC-MRI and perfusion-ventilation lung scintigraphy were evaluated. The PA-flow (cm3/sec) of MRI was calculated by multiplying maximum velocity (cm/sec) by region of interest (ROI) area (cm2) of measured main pulmonary artery using phase contrast method. The left to right ratio (R/L ratio) of PA-flow measured by PC-MRI was compared with the R/L ratios of the date of perfusion-ventilation lung scintigraphy. The R/L ratios of PC-MRI and perfusion lung scintigraphy were 1.43 ± 1.07 and 1.35 ± 0.82, respectively. Both ratios showed excellent correlation( y=-0.50+1.30x, r=0.99,pperfusion lung scintigraphy in the patients with a past history of lung resection, even if their R/L ratios of perfusion lung scintigraphy differed from those of ventilation lung scintigraphy. These results revealed that the PA-flow could be accurately measured by PC-MRI without contrast medium and nuclear medicine instruments.

  16. Nocturnal variations in peripheral blood flow, systemic blood pressure, and heart rate in humans

    DEFF Research Database (Denmark)

    Sindrup, J H; Kastrup, J; Christensen, H;

    1991-01-01

    Subcutaneous adipose tissue blood flow rate, together with systemic arterial blood pressure and heart rate under ambulatory conditions, was measured in the lower legs of 15 normal human subjects for 12-20 h. The 133Xe-washout technique, portable CdTe(Cl) detectors, and a portable data storage unit...... were used for measurement of blood flow rates. An automatic portable blood pressure recorder and processor unit was used for measurement of systolic blood pressure, diastolic blood pressure, and heart rate every 15 min. The change from upright to supine position at the beginning of the night period...... was associated with a 30-40% increase in blood flow rate and a highly significant decrease in mean arterial blood pressure and heart rate (P less than 0.001 for all). Approximately 100 min after the subjects went to sleep an additional blood flow rate increment (mean 56%) and a simultaneous significant decrease...

  17. Sexual Response in Women with Type 1 Diabetes Mellitus: A Controlled Laboratory Study Measuring Vaginal Blood Flow and Subjective Sexual Arousal.

    Science.gov (United States)

    Both, Stephanie; Ter Kuile, Moniek; Enzlin, Paul; Dekkers, Olaf; van Dijk, Marieke; Weijenborg, Philomeen

    2015-08-01

    Previous studies have indicated that women with diabetes mellitus are at higher risk to develop sexual dysfunctions. In the current study, we hypothesized that lower genital arousal response-as a consequence of diabetes-related damage to nerves and blood vessels-might play a part in these higher prevalence rates. Vaginal blood flow, subjective sexual response, and clitoral sensitivity were compared between women with diabetes and healthy controls, and associations with diabetes complications were investigated. In pre- and postmenopausal women with type 1 diabetes (n = 42) and healthy controls (n = 46), vaginal blood flow was measured as vaginal pulse amplitude (VPA). VPA was assessed at rest, during erotic film viewing, and during vibrotactile clitoral stimulation. Subjective sexual arousal was measured using a questionnaire. Clitoral sensitivity was assessed by a vibration perception test. Data on diabetes complications were obtained from medical records, and neuropathy was assessed by quantitative sensory testing. VPA, subjective sexual arousal, and clitoral sensitivity were not significantly different between women with diabetes and controls. Nevertheless, women with diabetes who had retinopathy showed significantly lower VPA than women without retinopathy, and women with diabetes who had neuropathy showed significantly higher sensation thresholds for vibrotactile clitoral stimulation. The results do not support the hypothesis of a disrupted genital arousal response in women with diabetes. However, the observed associations between retinopathy and vaginal blood flow, and between neuropathy and clitoral sensitivity, suggest that diabetes-related complications might adversely affect the physiological basis of female sexual response. PMID:26054485

  18. Compromised cerebrovascular modulation in chronic anxiety: evidence from cerebral blood flow velocity measured by transcranial Doppler sonography

    Institute of Scientific and Technical Information of China (English)

    Hong-Liang Zhang; Zhen-Ni Guo; Ge Yang; Le Yang; Ke Han; Jiang Wu; Yingqi Xing; Yi Yang

    2012-01-01

    Objective Cerebral autoregulation (CA) is the mechanism by which constant cerebral blood flow is maintained despite changes in cerebral perfusion pressure.CA can be evaluated by dynamic monitoring of cerebral blood flow velocity (CBFV) with transcranial Doppler sonography (TCD).The present study aimed to explore CA in chronic anxiety.Methods Subjects with Hamilton anxiety scale scores ≥14 were enrolled and the dynamic changes of CBFV in response to an orthostatic challenge were investigated using TCD.Results In both the anxious and the healthy subjects,the mean CBFV was significantly lower in the upright position than when supine.However,the CBFV changes from supine to upright differed between the anxious and the healthy groups.Anxious subjects showed more pronounced decreases in CBFV with abrupt standing.Conclusion Our results indicate that cerebrovascular modulation is compromised in chronic anxiety; anxious subjects have some insufficiency in maintaining cerebral perfusion after postural change.Given the fact that anxiety and impaired CA are associated with cardiovascular disease,early ascertainment of compromised cerebrovascular modulation using TCD might suggest interventional therapies in the anxious population,and improve the primary prevention of cardiovascular disease.

  19. Effect of sumatriptan on cerebral blood flow during migraine headache. Measurement by sequential SPECT used {sup 99m}Tc-ECD background subtraction method

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, Takashi; Torihara, Yoshito; Tsuneyoshi, Noritaka; Ikeda, Yoshitomo [Miyazaki Social Insurance Hospital (Japan)

    2001-07-01

    The present study was designed to examine the effect of sumatriptan on regional cerebral blood flow (CBF) during migraine headache. Nine cases were examined by {sup 99m}Tc-ECD background subtraction method for the absolute value measurement of regional CBF before and after sumatriptan injection. rCBF except for occipital and perioccipital lobes, were increased 10-20% during migraine headache and significant decreases were observed by sumatriptan injection. Two cases of nine had transiently increased systemic blood pressure and cardiac pulse rate, however, all cases improved migraine headache after injection of sumatriptan. (author)

  20. Palmar skin blood flow and temperature responses throughout endoscopic sympathectomy.

    Science.gov (United States)

    Crandall, Craig G; Meyer, Dan M; Davis, Scott L; Dellaria, Suzanne M

    2005-01-01

    Thoracic surgical sympathectomy is often performed to treat primary palmar and axillary hyperhidrosis. An increase in palmar skin temperature is frequently used to identify the success of the procedure. Because changes in palmar skin temperature occur secondary to changes in skin blood flow, the objective of this study was to test the hypothesis that monitoring palmar skin blood flow would provide greater temporal resolution relative to monitoring palmar skin temperature. In 11 patients with palmar and/or axillary hyperhidrosis, we measured palmar skin temperature and blood flow (via laser Doppler flowmetry) throughout the sympathectomy procedure. Five minutes after the initial cautery, skin blood flow increased from 48 +/- 7 perfusion units to 121 +/- 17 perfusion units (P 0.05). The time required to reach peak skin blood flow (22 +/- 3 min) was significantly less than the time required to reach peak skin temperature (34 +/- 0.3 min; P <0.001). Finally at 5, 10, and 15 min after the initial cautery, skin blood flow increased to a larger percentage of the total increase in skin blood flow relative skin temperature (all P <0.006). These data suggest that monitoring skin blood flow provides greater temporal resolution when compared with monitoring skin temperature during thoracic sympathectomy. However, the initial cautery of the parietal pleura over the ganglion may result in increases in skin blood flow before physical disruption of the ganglion. This occurrence may limit the utility of skin blood-flow measurements in identifying the success of the procedure. PMID:15616091

  1. Human brain mapping under increasing cognitive complexity using regional cerebral blood flow measurements and positron emission tomography.

    Science.gov (United States)

    Law, Ian

    2007-11-01

    Measurement of the regional cerebral blood flow (rCBF) is an important parameter in the evaluation of cerebral function. With positron emission tomography (PET) rCBF has predominantly been quantified using the short-lived radiotracer oxygen-15 labelled water (H 2 15 O) and an adaptation of the Kety one-tissue compartment autoradiographic model. The values attained in putative grey matter, however, are systematically underestimated because of the limited scanner resolution. For this reason we applied a dynamic kinetic two-tissue compartment model including a fast and a slow flow component each with a perfusable tissue fraction. In the fast component rCBF was 2-2.5 times greater than grey matter values using traditional autoradiography in both human and monkey. Visual stimulation in human gave a corrected rCBF increase of approximately 40%. Visual stimulation was also used to indirectly validate carbon-10 labelled carbondioxide ( 10 CO 2 ), a new very short-lived rCBF PET tracer with a half-life of only 19.3 seconds. This allowed an increase in the number of independent PET scans per subject from 12-14 using H 2 15 O to 64 using 10 CO 2 . The experiment demonstrated a maximal activation response in the visual cortex at a 10-15 Hz stimulation frequency. The use of the rCBF PET mapping technique is illustrated by studies of the organization of language and the oculomotor system. With respect to the former, we found confirmation of neuropsychological evidence of the involvement of the left supramarginal/angular gyrus in reading in Japanese of a phonologically based script system, Kana, and of the left posterior inferior temporal gyrus in reading of a morphogram based script system, Kanji. Concerning the organization of the oculomotor system we found overlapping areas in fronto-parietal cortex involved in maintaining visual fixation, and performing visually guided and imagined eye movements. These data show that overt eye movements are not a prerequisite of the

  2. The effect of morphine on regional cerebral blood flow measured by 99mTc-ECD SPECT in dogs.

    Science.gov (United States)

    Adriaens, Antita; Peremans, Kathelijne; Waelbers, Tim; Vandermeulen, Eva; Croubels, Siska; Duchateau, Luc; Dobbeleir, André; Audenaert, Kurt; Eersels, Jos; Vermeire, Simon; De Spiegeleer, Bart; Polis, Ingeborgh

    2014-01-01

    To gain insights into the working mechanism of morphine, regional cerebral blood flow (rCBF) patterns after morphine administration were assessed in dogs. In a randomized cross-over experimental study, rCBF was estimated with 99mTc-Ethylcysteinate Dimer single photon emission computed tomography in 8 dogs at baseline, at 30 minutes and at 120 minutes after a single bolus of morphine. Perfusion indices (PI) in the frontal, parietal, temporal and occipital cortex and in the subcortical and cerebellar region were calculated. PI was significantly decreased 30 min after morphine compared to baseline in the right frontal cortex. The left parietal cortex and subcortical region showed a significantly increased PI 30 min after morphine compared to baseline. No significant differences were noted for the other regions or at other time points. In conclusion, a single bolus of morphine generated a changing rCBF pattern at different time points.

  3. The effect of morphine on regional cerebral blood flow measured by 99mTc-ECD SPECT in dogs.

    Directory of Open Access Journals (Sweden)

    Antita Adriaens

    Full Text Available To gain insights into the working mechanism of morphine, regional cerebral blood flow (rCBF patterns after morphine administration were assessed in dogs. In a randomized cross-over experimental study, rCBF was estimated with 99mTc-Ethylcysteinate Dimer single photon emission computed tomography in 8 dogs at baseline, at 30 minutes and at 120 minutes after a single bolus of morphine. Perfusion indices (PI in the frontal, parietal, temporal and occipital cortex and in the subcortical and cerebellar region were calculated. PI was significantly decreased 30 min after morphine compared to baseline in the right frontal cortex. The left parietal cortex and subcortical region showed a significantly increased PI 30 min after morphine compared to baseline. No significant differences were noted for the other regions or at other time points. In conclusion, a single bolus of morphine generated a changing rCBF pattern at different time points.

  4. Noninvasive blood pressure measurement in large vessels

    International Nuclear Information System (INIS)

    Pulse pressure in the aorta was evaluated by the measurement of pulse wave velocity (PWV) and blood flow velocity (BFV). PWV reflects the elasticity of the vessel and was determined by a time-of-flight method. BFV was measured by analyzing the change of magnetization decay due to flow in multiecho experiments. If one neglects pulse wave reflections at vascular branch points and flow resistance due to blood viscosity, pulse pressure is proportional to PWV and BFV. Noninvasive MR imaging measurements were obtained in 12 patients, all of whom underwent correlative arterial catheterization. Values varied between 35 and 100 mm Hg. The results demonstrated a high correlation between the two methods

  5. Metabolic and kinetic considerations in the use of [125I]HIPDM for quantitative measurement of regional cerebral blood flow

    International Nuclear Information System (INIS)

    The metabolic degradation and the kinetics of the cerebral uptake of N,N,N'-trimethyl-N'-(2-hydroxy-3-methyl-5-[125I]iodobenzyl)-1, 3-propanediamine ([125I]HIPDM) have been studied in conscious, adult male Sprague-Dawley rats to determine its suitability as a tracer for the quantitative measurement of regional CBF (rCBF). rCBF was calculated by the indicator fractionation and the tissue equilibration methods in experiments of different durations up to 1 h. The values of rCBF obtained with [125I]HIPDM were compared with those obtained in concurrent measurements with [14C]iodoantipyrine in the same animals. Results of the experiments demonstrate that [125I]HIPDM is an inadequate tracer for use with the indicator fractionation method and that any method that employs [125I]HIPDM for the determination of rCBF must take into account its metabolic degradation, diffusion limitations, and bidirectional flux across the blood-brain barrier. With the tissue equilibration method, consistent determinations of rCBF may be possible with [125I]HIPDM by measurement of the time course of its concentration in arterial blood, corrected for the presence of 125I-labeled metabolic products, and its concentration in the brain at any time up to 1 h after its administration. The method may be adapted to measure rCBF in humans by means of single-photon emission tomography with [123I]HIPDM

  6. Deuterium Nuclear Magnetic Resonance Measurements of Blood Flow and Tissue Perfusion Employing 2H2O as a Freely Diffusible Tracer

    Science.gov (United States)

    Ackerman, Joseph J. H.; Ewy, Coleen S.; Becker, Nancy N.; Shalwitz, Robert A.

    1987-06-01

    The use of deuterium oxide (2H2O) is proposed as a freely diffusible nuclear magnetic resonance (NMR) blood flow and tissue perfusion tracer of potential clinical utility. Deuterium is a stable, nonradiative isotope commercially available as 2H2O at enrichment levels of essentially 100%--i.e., 110 molar equivalent deuterium. This high concentration, together with the short relaxation time of the spin 1 (quadrupole) deuterium nuclide, provides substantial sensitivity for NMR spectroscopy. As a result, when 2H2O is administered in a bolus fashion to a specific tissue or organ in vivo, the deuterium NMR intensity time course can be analyzed, using mathematical models developed by others for radiolabeled tracers, to measure the rate of blood flow and tissue perfusion. Such an application is demonstrated herein at a static magnetic field of 8.5 tesla. Using single-compartment flow modeling, hepatic blood flow and tissue perfusion in fasted (18 hr) male Sprague-Dawley rats was determined to be 61 ± 17 (mean ± SD) ml/100 g per min (n = 5).

  7. TU-A-12A-09: Absolute Blood Flow Measurement in a Cardiac Phantom Using Low Dose CT

    Energy Technology Data Exchange (ETDEWEB)

    Ziemer, B; Hubbard, L; Lipinski, J; Molloi, S [University of California, Irvine, CA (United States)

    2014-06-15

    Purpose: To investigate a first pass analysis technique to measure absolute flow from low dose CT images in a cardiac phantom. This technique can be combined with a myocardial mass assignment to yield absolute perfusion using only two volume scans and reduce the radiation dose to the patient. Methods: A four-chamber cardiac phantom and perfusion chamber were constructed from poly-acrylic and connected with tubing to approximate anatomical features. The system was connected to a pulsatile pump, input/output reservoirs and power contrast injector. Flow was varied in the range of 1-2.67 mL/s with the pump operating at 60 beats/min. The system was imaged once a second for 14 seconds with a 320-row scanner (Toshiba Medical Systems) using a contrast-enhanced, prospective-gated cardiac perfusion protocol. Flow was calculated by the following steps: subsequent images of the perfusion volume were subtracted to find the contrast entering the volume; this was normalized by an upstream, known volume region to convert Hounsfield (HU) values to concentration; this was divided by the subtracted images time difference. The technique requires a relatively stable input contrast concentration and no contrast can leave the perfusion volume before the flow measurement is completed. Results: The flow calculated from the images showed an excellent correlation with the known rates. The data was fit to a linear function with slope 1.03, intercept 0.02 and an R{sup 2} value of 0.99. The average root mean square (RMS) error was 0.15 mL/s and the average standard deviation was 0.14 mL/s. The flow rate was stable within 7.7% across the full scan and served to validate model assumptions. Conclusion: Accurate, absolute flow rates were measured from CT images using a conservation of mass model. Measurements can be made using two volume scans which can substantially reduce the radiation dose compared with current dynamic perfusion techniques.

  8. Regional blood flow studies with radioisotopes

    International Nuclear Information System (INIS)

    The methodological approaches to blood flow analysis include (1) diffusible indicator methods, (2) clearance techniques and (3) nondiffusible indicator methods. In each case, accurate measurements of blood flow can be obtained by developing mathematical models which relate the time-dependent observation derived from following the fate of a radiotracer as a function of time to the physiological process itself. Application of these models to biological systems involves constraints and necessitates compromises which may affect the validity of the measurements. Nevertheless, when these techniques are carefully applied and adequately validated, they have provided critical physiological information about such organ systems as the brain and kidney and promise to provide diagnostic information in patients with suspected coronary and peripheral vascular disease

  9. Combining magnetic resonance measurements with numerical simulations - Extracting blood flow physiology information relevant to the investigation of intracranial aneurysms in the circle of Willis

    Energy Technology Data Exchange (ETDEWEB)

    Zuleger, Dorothea I., E-mail: zuleger@ltnt.iet.mavt.ethz.c [Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Zurich (Switzerland); Institute of Neuroradiology, University Hospital Zurich, Zurich (Switzerland); Poulikakos, Dimos [Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Zurich (Switzerland); Valavanis, Anton; Kollias, Spyros S. [Institute of Neuroradiology, University Hospital Zurich, Zurich (Switzerland)

    2010-12-15

    Cerebral aneurysms in the region of the circle of Willis have an incidence of 3-6% in western populations and involve the risk of rupture with subsequent subarachnoidal bleeding. The patient specific blood flow patterns are of substantial importance for understanding the pathogenesis of the lesions and may eventually contribute to deciding on the most efficient treatment procedure for a specific patient. A non-invasive method for performing in vivo measurements on blood velocity is 4D phase-contrast magnetic resonance angiography (PC-MRA), on the basis of which a flow field with all its parameters can be simulated. We are using this approach to investigate the hemodynamic parameters in the circle of Willis and, by analyzing the values at common locations of aneurysms, trying to find potential parameters to predict the development of aneurysms. Methodologically, we are acquiring the artery geometry with 3D-time-of-flight magnetic resonance (TOF) measurements and the blood velocity in the feeding arteries with 4D PC-MRA measurements in a healthy volunteer. These measurements are combined with computational fluid dynamics (CFD) to describe detailed hemodynamic patterns within the circle of Willis.

  10. The effect of isometric exercise of the hand on the synovial blood flow in patients with rheumatoid arthritis measured by color Doppler ultrasound

    DEFF Research Database (Denmark)

    Ellegaard, Karen; Torp-Pedersen, Søren; Lund, Hans;

    2013-01-01

    In 90% of patients with rheumatoid arthritis (RA), the joints of the hand are affected. Studies of grip strength training have not indicated a negative effect on disease activity after training. Introduction of ultrasound Doppler (USD) to measure increased blood flow induced by inflammation has...... made it possible to investigate the direct effect on blood supply in the synovium after training. In this case-control study, 24 patients with RA with USD activity in the wrist joint participated. The USD activity was measured by the color fraction (CF) (CF = colored pixels/total number of pixels...... in ROI). Twenty-four patients were assigned to an 8-week grip strength training program. At baseline and after 8 weeks of training, an USD examination of the wrist joint was performed. In the training group, we measured grip strength and pain in the wrist joint. Six patients withdrew from the training...

  11. Dexmedetomidine decreases the oral mucosal blood flow.

    Science.gov (United States)

    Kawaai, Hiroyoshi; Yoshida, Kenji; Tanaka, Eri; Togami, Kohei; Tada, Hitoshi; Ganzberg, Steven; Yamazaki, Shinya

    2013-12-01

    There is an abundance of blood vessels in the oral cavity, and intraoperative bleeding can disrupt operations. There have been some interesting reports about constriction of vessels in the oral cavity, one of which reported that gingival blood flow in cats is controlled by sympathetic α-adrenergic fibres that are involved with vasoconstriction. Dexmedetomidine is a sedative and analgesic agent that acts through the α-2 adrenoceptor, and is expected to have a vasoconstrictive action in the oral cavity. We have focused on the relation between the effects of α-adrenoceptors by dexmedetomidine and vasoconstriction in oral tissues, and assessed the oral mucosal blood flow during sedation with dexmedetomidine. The subjects comprised 13 healthy male volunteers, sedated with dexmedetomidine in a loading dose of 6 μg/kg/h for 10 min and a continuous infusion of 0.7 μg/kg/h for 32 min. The mean arterial pressure (MAP), heart rate (HR), cardiac output (CO), stroke volume (SV), systemic vascular resistance (SVR), and palatal mucosal blood flow (PMBF) were measured at 0, 5, 10, 12, 22, and 32 min after the start of the infusion. The HR, CO, and PBMF decreased significantly during the infusion even though there were no differences in the SV. The SVR increased significantly but the PMBF decreased significantly. In conclusion, PMBF was reduced by the mediating effect of dexmedetomidine on α-2 adrenoceptors. PMID:23958351

  12. MUSCLE METABOLISM WITH BLOOD FLOW RESTRICTION IN CHRONIC FATIGUE SYNDROME

    OpenAIRE

    McCully, Kevin K; Smith, Sinclair; Rajaei, Sheeva; Leigh, John S.; Natelson, Benjamin H

    2003-01-01

    The purpose of this study was to determine if chronic fatigue syndrome (CFS) is associated with reduced blood flow and muscle oxidative metabolism. Patients with CFS according to CDC criteria (n=19) were compared to normal sedentary subjects (n = 11). Muscle blood flow was measured in the femoral artery with Doppler ultrasound after exercise. Muscle metabolism was measured in the medial gastrocnemius muscle using 31P magnetic resonance spectroscopy (MRS). Muscle oxygen saturation and blood vo...

  13. Laser Doppler flowmetry for bone blood flow measurements: helium-neon laser light attenuation and depth of perfusion assessment.

    Science.gov (United States)

    Nötzli, H P; Swiontkowski, M F; Thaxter, S T; Carpenter, G K; Wyatt, R

    1989-01-01

    Laser Doppler flowmetry (LDF) has been successfully used in clinical and experimental settings to evaluate bone perfusion but unanswered questions regarding its capabilities and limitations still remain. This study was undertaken to determine absorption of He-Ne laser light (632.8 nm) and maximum depth for flow assessment (threshold thickness) under optimal conditions in bone. Light transmittance in bovine bone samples of femora and tibia was measured after each step of grinding and depth of penetration calculated. The threshold thickness was obtained by placing the same samples in a flow chamber where a solution of 2% latex circulated beneath; flow was detected by a laser Doppler probe resting on top of the sample. The results showed a significantly higher depth of penetration for trabecular than for cortical bone. A regression analysis showed a high correlation between the inorganic fraction of the bone and the depth of penetration. The maximum depth at which the laser Doppler probe can evaluate flow in bone conditions was found to be 2.9 +/- 0.2 mm in cortical bone, 3.5 +/- 0.3 mm in bone covered by 1 mm cartilage and 3.5 +/- 0.2 mm in trabecular bone. The study showed the limitations of LDF in bone and their correlations to various bone properties.

  14. Data adaptive estimation of transversal blood flow velocities

    DEFF Research Database (Denmark)

    Pirnia, E.; Jakobsson, A.; Gudmundson, E.;

    2014-01-01

    The examination of blood flow inside the body may yield important information about vascular anomalies, such as possible indications of, for example, stenosis. Current Medical ultrasound systems suffer from only allowing for measuring the blood flow velocity along the direction of irradiation...... the transversal blood flow. In this paper, we propose a novel data-adaptive blood flow estimator exploiting this modulation scheme. Using realistic Field II simulations, the proposed estimator is shown to achieve a notable performance improvement as compared to current state-of-the-art techniques....

  15. Regional cerebral blood flow in focal cortical epilepsy

    DEFF Research Database (Denmark)

    Hougaard, Kristina Dupont; Oikawa, T; Sveinsdottir, E;

    1976-01-01

    Regional cerebral blood flow (rCBF) was studied in ten patients with focal cortical epilepsy. The blood flow was measured by the intra-arterial injection of xenon 133 (133Xe), and the isotope clearance was recorded by a multidetector scintillation camera with 254 detectors. Three patients were...

  16. Influence of temporal noise on the skin blood flow measurements performed by cooled thermal imaging camera: limit possibilities within each physiological frequency range

    Science.gov (United States)

    Sagaidachnyi, A. A.; Volkov, I. U.; Fomin, A. V.

    2016-04-01

    This paper describes limit possibilities of modern cooled thermal imaging cameras as a tool for estimation of blood flow oscillations at the surface of living body. Skin temperature oscillations, as we assumed, are a consequence of the blood flow oscillations. We considered the temperature sensitivity 0.01-0.02 °C as a typical for the most of modern cooled long wave thermal imaging cameras. Fourier filter used to investigate the temperature signal separately within endothelial, neurogenic, myogenic, respiratory and cardiac frequency ranges. The level of temporal noise has been estimated during measurements of no living body with stabilized temperature ~ 24°C. The level of temperature oscillations has been calculated for the group of healthy subjects within each frequency range. Thus, we were able to determine signal-to-noise ratio within frequency band [0.001, 1] Hz. As a result, we determine that skin temperature oscillations measured by thermal imaging camera with sensitivity 0.02°C have the upper frequency limit ~ 0.2 Hz. In other words, within the respiratory and cardiac frequency ranges of blood flow oscillations the noise level exceeds signal one, and temperature measurements at the skin surface are practically useless. The endothelial, neurogenic and myogenic components of the temperature oscillations contain ~98% of the total spectral power of the signal. We have plot the empirical extrapolated curve of sensitivity of thermal imaging camera vs. frequency of the temperature oscillations. The data analysis shows that measurements of skin temperature oscillations within respiratory and cardiac ranges require the temperature sensitivity at least ~ 0.01°C and 0.001°C, respectively.

  17. Correlation of skin temperature and blood flow oscillations

    Science.gov (United States)

    Sagaidachnyi, A. A.; Usanov, D. A.; Skripal, A. V.; Fomin, A. V.

    2012-03-01

    Interrelation of skin temperature and blood flow oscillations of fingers under normal conditions in healthy subjects has been investigated. Oscillations of a blood flow were measured by means of photoplethysmography; oscillations of a temperature were registered by means of thermal imaging camera. The method of blood flow reconstruction by temperature oscillations with the use of the Pennes bioheat transfer equation and a definition of delay time of a temperature in relation to blood flow signal has been described. Temperature oscillations have a lag in relation to blood flow oscillations of approximately 10-20 seconds. Delay time of temperature waves can be used for the definition of an effective thickness of a tissue layer separating blood vessels and skin surface. Use of the described technique of comparison of finger blood flow and temperature oscillations allows to raise correlation coefficient of the signals from 0.35 to 0.63 on average, which testifies of high degree of conditionality of temperature oscillations by blood flow oscillations. The considered method of non-contact restoration of blood flow oscillations by means of temperature oscillation measurements might find practical application in skin thermal lesions research, research of influence of physical and chemical factors on a skin microcirculation.

  18. Improved method for noninvasive measurement of regional cerebral blood flow by 133Xe inhalation. I. description of method and normal values obtained in healthy volunteers

    International Nuclear Information System (INIS)

    A clinical method for noninvasive measurement of regional cerebral blood flow (rCBF) and blood volume (rCBV) is described, based on Obrist's 10 minute, desaturation method after 1 minute inhalation of 133Xe. Sixteen collimated probes are placed over both hemispheres and brain stem-cerebellar regions. End-tidal 133Xe curves are used for correction of recirculation. KEV discriminators are set to record gamma and x-ray activity separately. Values are printed out automatically by a computer on a brain map. Extracerebral contamination is reduced by (1) computing curves from gamma activity, (2) applying pressure on the scalp beneath the probes, (3) 1 minute inhalation of 133Xe and recording desaturation curves for 10 minutes, thereby minimizing slow clearance from extracranial tissues. Normal values for both fast and slow compartments are reproducible and are in good agreement with the carotid injection method. The speech dominant hemisphere has higher flow than the right under conditions described. Posterior portions of the cranium over the cerebellum and brain stem appear to have higher flow gray values than the cerebral cortex. Gray matter flow decreases with advancing age

  19. Measurement of cerebral blood flow by intravenous xenon-133 technique and a mobile system. Reproducibility using the Obrist model compared to total curve analysis

    DEFF Research Database (Denmark)

    Schroeder, T; Holstein, P; Lassen, N A;

    1986-01-01

    The recent development of a mobile 10 detector unit, using i.v. Xenon-133 technique, has made it possible to perform repeated bedside measurements of cerebral blood flow (CBF). Test-retest studies were carried out in 38 atherosclerotic subjects, in order to evaluate the reproducibility of CBF level...... and side-to-side asymmetry. Data were analysed according to the Obrist model and the results compared with those obtained using a model correcting for the air passage artifact. Reproducibility was of the same order of magnitude as reported using stationary equipment. The side-to-side CBF asymmetry...... was considerably more reproducible than CBF level. Using a single detector instead of five regional values averaged as the hemispheric flow increased standard deviation of CBF level by 10-20%, while the variation in asymmetry was doubled. In optimal measuring conditions the two models revealed no significant...

  20. Cerebellar blood flow in methylmercury poisoning (Minamata disease)

    International Nuclear Information System (INIS)

    We looked at regional cerebellar blood flow in patients with Minamata disease (MD) using technetium-99 m ethyl cysteinate dimer (99m-Tc-ECD). We carried out single-photon emission computed tomography (SPECT) on 15 patients with MD (eight men, seven women, aged 51-78 years, mean 70.5 years) and 11 control subjects (eight men, three women, aged 62-80 years, mean 72.5 years). Regional blood flow was measured in the superior, middle, and inferior portions of the cerebellar hemispheres, and the frontal, temporal and occipital cerebral lobes. The degree of cerebellar atrophy was assessed on MRI. There were significant differences in regional blood flow in all parts of the cerebellum between patients and control, but no significant decrease was observed in the cerebrum. Blood flow was lower in the inferior cerebellum than in the other parts. Even in patients without cerebellar atrophy, flow was significantly decreased regional blood flow in the inferior part. (orig.)

  1. Regional cerebral blood flow measured by microsphere technique in experimental animals: Technical notes for the use of albumin microspheres in rats

    International Nuclear Information System (INIS)

    The aim of this study was to validate the use of 99mTc-albumin microspheres (AM) to measure regional cerebral blood flow (rCBF) in rats. In vitro stability and in vivo rheology of AM were tested: the free fraction of 99mTc was found to be less than 3(of the total radioactivity for at least 3 h after labelling); arterovenous shunting of AM during vascular brain transit was negligible. In addition, rCBF values obtained in different brain regions were compared with those of previous studies made using synthetic microspheres and iodoantipyrine

  2. A Robust System for Longitudinal Knee Joint Edema and Blood Flow Assessment Based on Vector Bioimpedance Measurements.

    Science.gov (United States)

    Hersek, Sinan; Töreyin, Hakan; Inan, Omer T

    2016-06-01

    We present a robust vector bioimpedance measurement system for longitudinal knee joint health assessment, capable of acquiring high resolution static (slowly varying over the course of hours to days) and dynamic (rapidly varying on the order of milli-seconds) bioresistance and bioreactance signals. Occupying an area of 78×90 mm(2) and consuming 0.25 W when supplied with ±5 V, the front-end achieves a dynamic range of 345 Ω and noise floor of 0.018 mΩrms (resistive) and 0.055 mΩrms (reactive) within a bandwidth of 0.1-20 Hz. A microcontroller allows real-time calibration to minimize errors due to environmental variability (e.g., temperature) that can be experienced outside of lab environments, and enables data storage on a micro secure digital card. The acquired signals are then processed using customized physiology-driven algorithms to extract musculoskeletal (edema) and cardiovascular (local blood volume pulse) features from the knee joint. In a feasibility study, we found statistically significant differences between the injured and contralateral static knee impedance measures for two subjects with recent unilateral knee injury compared to seven controls. Specifically, the impedance was lower for the injured knees, supporting the physiological expectations for increased edema and damaged cell membranes. In a second feasibility study, we demonstrate the sensitivity of the dynamic impedance measures with a cold-pressor test, with a 20 mΩ decrease in the pulsatile resistance associated with increased downstream peripheral vascular resistance. The proposed system will serve as a foundation for future efforts aimed at quantifying joint health status continuously during normal daily life. PMID:26841413

  3. Regional cerebral blood flow in childhood headache

    International Nuclear Information System (INIS)

    Regional cerebral blood flow (rCBF) was measured in 16 cranial regions in 23 children and adolescents with frequent headaches using the non-invasive Xenon-133 inhalation technique. Blood flow response to 5% carbon dioxide (CO2) was also determined in 21 patients, while response to 50% oxygen was measured in the two patients with hemoglobinopathy. Included were 10 patients with a clinical diagnosis of migraine, 4 with musculoskeletal headaches, and 3 with features of both types. Also studied were 2 patients with primary thrombocythemia, 2 patients with hemoglobinopathy and headaches, 1 patient with polycythemia, and 1 with headaches following trauma. With two exceptions, rCBF determinations were done during an asymptomatic period. Baseline rCBF values tended to be higher in these young patients than in young adults done in our laboratory. Localized reduction in the expected blood flow surge after CO2 inhalation, most often noted posteriorly, was seen in 8 of the 13 vascular headaches, but in none of the musculoskeletal headache group. Both patients with primary thrombocythemia had normal baseline flow values and altered responsiveness to CO2 similar to that seen in migraineurs; thus, the frequently reported headache and transient neurologic signs with primary thrombocythemia are probably not due to microvascular obstruction as previously suggested. These data support the concept of pediatric migraine as a disorder of vasomotor function and also add to our knowledge of normal rCBF values in younger patients. Demonstration of altered vasomotor reactivity to CO2 could prove helpful in children whose headache is atypical

  4. Water-displacement plethysmography: a technique for the simultaneous thermal manipulation and measurement of whole-hand and whole-foot blood flows

    International Nuclear Information System (INIS)

    The purpose of this project was to design, construct and validate water-displacement plethysmographs for the forearm, hand and foot that could clamp segmental skin temperature whilst simultaneously measuring cutaneous blood flow. Two experiments were performed. In the first, the forearm plethysmograph was validated against a mercury-in-silastic plethysmograph under thermoneutral conditions, with and without forearm heating. Cutaneous vascular conductance was elevated almost three-fold by this treatment, however, there were no significant differences between the two forms of plethysmography in either state (P > 0.05). In study two, hand and foot blood flows were measured under clamped thermoneutral conditions, but with three local skin temperature treatments (5, 25, 40 °C). The hand had significantly higher blood flows than the foot at both 25 °C (4.07 versus 2.20 mL.100 mL − 1.min − 1; P < 0.05) and 40 °C (8.20 versus 4.47 mL.100 mL − 1.min − 1; P < 0.05). The foot was maximally constricted during the two lower temperatures, yet the cutaneous thermal sensitivity of the hand was almost two-fold greater (P < 0.05). This evidence supports the significant role played by these appendages in heat loss and conservation, and these plethysmographs will now be used to map cutaneous vascular responses (forearm, hand, calf, foot) across combinations of core and local skin temperatures. (paper)

  5. Modified Beer-Lambert law for blood flow

    Science.gov (United States)

    Baker, Wesley B.; Parthasarathy, Ashwin B.; Busch, David R.; Mesquita, Rickson C.; Greenberg, Joel H.; Yodh, A. G.

    2015-03-01

    The modified Beer-Lambert law is among the most widely used approaches for analysis of near-infrared spectroscopy (NIRS) reflectance signals for measurements of tissue blood volume and oxygenation. Briefly, the modified Beer-Lambert paradigm is a scheme to derive changes in tissue optical properties based on continuous-wave (CW) diffuse optical intensity measurements. In its simplest form, the scheme relates differential changes in light transmission (in any geometry) to differential changes in tissue absorption. Here we extend this paradigm to the measurement of tissue blood flow by diffuse correlation spectroscopy (DCS). In the new approach, differential changes of the intensity temporal auto-correlation function at a single delay-time are related to differential changes in blood flow. The key theoretical results for measurement of blood flow changes in any tissue geometry are derived, and we demonstrate the new method to monitor cerebral blood flow in a pig under conditions wherein the semi-infinite geometry approximation is fairly good. Specifically, the drug dinitrophenol was injected in the pig to induce a gradual 200% increase in cerebral blood flow, as measured with MRI velocity flow mapping and by DCS. The modified Beer-Lambert law for flow accurately recovered these flow changes using only a single delay-time in the intensity auto-correlation function curve. The scheme offers increased DCS measurement speed of blood flow. Further, the same techniques using the modified Beer-Lambert law to filter out superficial tissue effects in NIRS measurements of deep tissues can be applied to the DCS modified Beer-Lambert law for blood flow monitoring of deep tissues.

  6. Use of Caval Subtraction 2D Phase-Contrast MR Imaging to Measure Total Liver and Hepatic Arterial Blood Flow: Preclinical Validation and Initial Clinical Translation.

    Science.gov (United States)

    Chouhan, Manil D; Mookerjee, Rajeshwar P; Bainbridge, Alan; Walker-Samuel, Simon; Davies, Nathan; Halligan, Steve; Lythgoe, Mark F; Taylor, Stuart A

    2016-09-01

    Purpose To validate caval subtraction two-dimensional (2D) phase-contrast magnetic resonance (MR) imaging measurements of total liver blood flow (TLBF) and hepatic arterial fraction in an animal model and evaluate consistency and reproducibility in humans. Materials and Methods Approval from the institutional ethical committee for animal care and research ethics was obtained. Fifteen Sprague-Dawley rats underwent 2D phase-contrast MR imaging of the portal vein (PV) and infrahepatic and suprahepatic inferior vena cava (IVC). TLBF and hepatic arterial flow were estimated by subtracting infrahepatic from suprahepatic IVC flow and PV flow from estimated TLBF, respectively. Direct PV transit-time ultrasonography (US) and fluorescent microsphere measurements of hepatic arterial fraction were the standards of reference. Thereafter, consistency of caval subtraction phase-contrast MR imaging-derived TLBF and hepatic arterial flow was assessed in 13 volunteers (mean age, 28.3 years ± 1.4) against directly measured phase-contrast MR imaging PV and proper hepatic arterial inflow; reproducibility was measured after 7 days. Bland-Altman analysis of agreement and coefficient of variation comparisons were undertaken. Results There was good agreement between PV flow measured with phase-contrast MR imaging and that measured with transit-time US (mean difference, -3.5 mL/min/100 g; 95% limits of agreement [LOA], ±61.3 mL/min/100 g). Hepatic arterial fraction obtained with caval subtraction agreed well with those with fluorescent microspheres (mean difference, 4.2%; 95% LOA, ±20.5%). Good consistency was demonstrated between TLBF in humans measured with caval subtraction and direct inflow phase-contrast MR imaging (mean difference, -1.3 mL/min/100 g; 95% LOA, ±23.1 mL/min/100 g). TLBF reproducibility at 7 days was similar between the two methods (95% LOA, ±31.6 mL/min/100 g vs ±29.6 mL/min/100 g). Conclusion Caval subtraction phase-contrast MR imaging is a simple and clinically

  7. The Physics of Coronary Blood Flow

    CERN Document Server

    Zamir, M

    2005-01-01

    Coronary blood flow is blood flow to the heart for its own metabolic needs. In the most common form of heart disease there is a disruption in this flow because of obstructive disease in the vessels that carry the flow. The subject of coronary blood flow is therefore associated mostly with the pathophysiology of this disease, rarely with dynamics or physics. Yet, the system responsible for coronary blood flow, namely the "coronary circulation," is a highly sophisticated dynamical system in which the dynamics and physics of the flow are as important as the integrity of the conducting vessels. While an obstruction in the conducting vessels is a fairly obvious and clearly visible cause of disruption in coronary blood flow, any discord in the complex dynamics of the system can cause an equally grave, though less conspicuous, disruption in the flow. This book is devoted specifically to the dynamics and physics of coronary blood flow. While relevance to the clinical and pathophysiological issues is clearly maintaine...

  8. Feasibility of measuring renal blood flow by phase-contrast magnetic resonance imaging in patients with autosomal dominant polycystic kidney disease

    Energy Technology Data Exchange (ETDEWEB)

    Spithoven, E.M.; Meijer, E.; Boertien, W.E.; Gaillard, C.A.J.M.; Jong, P.E. de; Gansevoort, R.T. [University of Groningen, Department of Nephrology, Community and Occupational Medicine, University Medical Center Groningen, PO Box 30.001, RB Groningen (Netherlands); Borns, C.; Kappert, P.; Greuter, M.J.W.; Jagt, E. van der [University of Groningen, Department of Radiology, Community and Occupational Medicine, University Medical Center Groningen, Groningen (Netherlands); Vart, P. [University of Groningen, Department of Health Sciences, Community and Occupational Medicine, University Medical Center Groningen, Groningen (Netherlands)

    2016-03-15

    Renal blood flow (RBF) has been shown to predict disease progression in autosomal dominant polycystic kidney disease (ADPKD). We investigated the feasibility and accuracy of phase-contrast RBF by MRI (RBF{sub MRI}) in ADPKD patients with a wide range of estimated glomerular filtration rate (eGFR) values. First, we validated RBF{sub MRI} measurement using phantoms simulating renal artery hemodynamics. Thereafter, we investigated in a test-set of 21 patients intra- and inter-observer coefficient of variation of RBF{sub MRI}. After validation, we measured RBF{sub MRI} in a cohort of 91 patients and compared the variability explained by characteristics indicative for disease severity for RBF{sub MRI} and RBF measured by continuous hippuran infusion. The correlation in flow measurement using phantoms by phase-contrast MRI was high and fluid collection was high (CCC=0.969). Technical problems that precluded RBF{sub MRI} measurement occurred predominantly in patients with a lower eGFR (34% vs. 16%). In subjects with higher eGFRs, variability in RBF explained by disease characteristics was similar for RBF{sub MRI} compared to RBF{sub Hip,} whereas in subjects with lower eGFRs, this was significantly less for RBF{sub MRI}. Our study shows that RBF can be measured accurately in ADPKD patients by phase-contrast, but this technique may be less feasible in subjects with a lower eGFR. (orig.)

  9. Feasibility of measuring renal blood flow by phase-contrast magnetic resonance imaging in patients with autosomal dominant polycystic kidney disease

    International Nuclear Information System (INIS)

    Renal blood flow (RBF) has been shown to predict disease progression in autosomal dominant polycystic kidney disease (ADPKD). We investigated the feasibility and accuracy of phase-contrast RBF by MRI (RBFMRI) in ADPKD patients with a wide range of estimated glomerular filtration rate (eGFR) values. First, we validated RBFMRI measurement using phantoms simulating renal artery hemodynamics. Thereafter, we investigated in a test-set of 21 patients intra- and inter-observer coefficient of variation of RBFMRI. After validation, we measured RBFMRI in a cohort of 91 patients and compared the variability explained by characteristics indicative for disease severity for RBFMRI and RBF measured by continuous hippuran infusion. The correlation in flow measurement using phantoms by phase-contrast MRI was high and fluid collection was high (CCC=0.969). Technical problems that precluded RBFMRI measurement occurred predominantly in patients with a lower eGFR (34% vs. 16%). In subjects with higher eGFRs, variability in RBF explained by disease characteristics was similar for RBFMRI compared to RBFHip, whereas in subjects with lower eGFRs, this was significantly less for RBFMRI. Our study shows that RBF can be measured accurately in ADPKD patients by phase-contrast, but this technique may be less feasible in subjects with a lower eGFR. (orig.)

  10. Kinetic and metabolic considerations in the use of (I-125) HIPDM as a tracer for quantitative measurement of regional cerebral blood flow

    International Nuclear Information System (INIS)

    The kinetics of cerebral uptake and the metabolism of radioactive iodine labeled HIPDM (N,N,N'-trimethyl-N'-(2-hydroxy-3-methyl-5-(I-125)iodobenzyl) -1,3-propanediamine)(I-125)HIPDM were studied in vivo in male adult Sprague-Dawley rats in order to evaluate the potential usefulness of this compound for quantitative measurement of regional cerebral blood flow (rCBF). The first pass extraction fraction of (I-125)HIPDM in brain was found to be about 80%. The arterial concentration of unmetabolized (I-125)HIPDM following an i.v. pulse drops rapidly and represents only 30% of the blood sample total radioactivity at 60 minutes, whereas 92% of the radioactivity in brain tissue at the same time is in unaltered (I-125)HIPDM. The rate constant for (I-125)HIPDM transport across the blood-brain barrier (BBB) was calculated on the basis of a distribution model in which bi-directional exchange of the tracer between brain tissue and vascular space is assumed. A kinetic model and an operational equation have been derived for determination of rCBF with this molecule. The model and equation take into account the three following factors: (a) incomplete first pass extraction; (b) HIPDM metabolism; (c) bi-directional flux of tracer across the BBB. The observations suggest that this molecule might be of potential usefulness for rCBF measurements with single photon emission tomography, provided that all these factors are evaluated in man

  11. Blood flow velocity in migraine attacks - a transcranial Doppler study

    Energy Technology Data Exchange (ETDEWEB)

    Zwetsloot, C.P.; Caekebeke, J.F.V.; Jansen, J.C.; Odink, J.; Ferrari, M.D. (Rijksuniversiteit Leiden (Netherlands))

    1991-05-01

    A pulsed Doppler device was used to measure blood flow velocities in the common carotid artery, the extracranial part of the internal carotid artery, the external carotid artery, the middle cerebral artery, and the anterior cerebral artery in 31 migraneurs without aura (n=27) and with aura (n=4), both during and ouside an attack. The aims were to compare blood flow velocity during and between migraine attacks and to study asymmetries of the blood flow velocity. Compared with blood flow velocity values obtained in the attack-free interval, blood flow velocity was lower during attacks without aura in both common carotid arteries, but not in the other extra- and intracranial vessels which were examined. However, during attacks of migraine with aura, blood flow velocity tended to be lower in all examined vessels. There were no asymmetries of the blood flow velocity. It is suggested that during migraine attacks without aura there is a dissociation in blood flow regulation in the common carotid and middle cerebral arteries. 20 refs., 2 tabs.

  12. Tissue blood flow mapping using laser technology

    Science.gov (United States)

    Wardell, Karin; Linden, Maria; Nilsson, Gert E.

    1995-03-01

    By the introduction of the laser Doppler perfusion imager (LDPI) the microvascular blood flow in a tissue area can be mapped by sequentially moving a laser beam over the tissue. The measurement is performed without touching the tissue and the captured perfusion values in the peripheral circulation are presented as a color-coded image. In the ordinary LDPI-set-up, 64 X 64 measurement sites cover an area in the range of about 10 - 150 cm2 depending on system settings. With a high resolution modification, recordings can be done on tissue areas as small as 1 cm2. This high resolution option has been assessed in animal models for the mapping of small vessels. To be able to record not only spatial but also temporal perfusion components of tissue blood flow, different local area scans (LAS) have been developed. These include single point recording as well as integration of either 2 X 2, 3 X 3, or 4 X 4 measurement sites. The laser beam is repeatedly moved in a quadratic pattern over the small tissue area of interest and the output value constitutes the average perfusion of all captured values within the actual region. For the evaluation, recordings were performed on healthy volunteers before and after application of a vasodilatating cream on the dorsal side of the hand.

  13. A simplified method of xenon-enhanced CT for regional cerebral blood flow (rCBF) measurement with reference to clinical experiences

    International Nuclear Information System (INIS)

    We introduced a simplified method of xenon-enhanced CT (SXe-CT) for obtaining the topographic regional cerebral blood flow (rCBF) map. In the SXe-CT, we used the method of brief (three to four minutes) inhalation of 40 % xenon. To shorten the period of xenon inhalation, we substituted a predetermined brain-blood partition coefficient (L) in the entire brain for the directly estimated L to calculate the rCBF value. Because of its non-invasiveness and simplicity, the SXe-CT can be applied to the patients with diseases in the central nervous system (CNS) without any difficulties. During the past three years, we performed the SXe-CT on 150 occasions in 100 subjects, including those with moyamoya disease, other ischemic cerebrovascular diseases, arteriovenous malformations and normal pressure hydrocephalus. In this paper, the rCBF values of seven normal healthy adults with a mean age of 24 years are reported and the flow maps of some cases of CNS diseases are presented. The normal mean value of the hemispheres was 53, those of the gray matter were in the range of 38 to 72, those of the white matter were in the range of 26 to 35 and those of the basal ganglia and thalamus were 55 to 88 (values are given in ml/100 g/min). The SXe-CT has potential advantages in obtaining clinically useful rCBF measurements. (author)

  14. [Abnormal cerebral blood flow distributions during the post-ictal phase of febrile status epilepticus in three pediatric patients measured by arterial spin labeling perfusion MRI].

    Science.gov (United States)

    Hirano, Keiko; Fukuda, Tokiko

    2016-05-01

    The ability to visualize brain perfusion is important for identifying epileptic foci. We present three pediatric cases showing asymmetrical cerebral blood flow (CBF) distributions during the post-ictal phase of febrile status epilepticus measured by arterial spin labeling (ASL) perfusion MRI. During the acute phase, regional CBF measurements in the areas considered including epileptic foci were higher than in the corresponding area of the contralateral hemisphere, though the exact quantitative value varied between cases. We could not identify the correct epileptogenic foci, because those ASL images were taken after the prolonged and extraordinary activation of neurons in the affected area. During the recovery phase, the differences reduced and the average regional CBF measurement was 54.6 ± 6.1 ml/100 g per minute, which was a little less than the number of previous ASL studies. ASL perfusion MRI imaging provides a method for evaluating regional CBF by using magnetically labeled arterial blood water as an endogenous tracer. With this technique, we can repeatedly evaluate both the brain structure and the level of perfusion at the same time. ASL is noninvasive and easily accessible, and therefore it could become a routine tool for assessment of perfusion in daily practice of pediatric neurology.

  15. The effect of isometric exercise of the hand on the synovial blood flow in patients with rheumatoid arthritis measured by color Doppler ultrasound.

    Science.gov (United States)

    Ellegaard, Karen; Torp-Pedersen, Søren; Lund, Hans; Pedersen, Kirsten; Henriksen, Marius; Danneskiold-Samsøe, Bente; Bliddal, Henning

    2013-01-01

    In 90% of patients with rheumatoid arthritis (RA), the joints of the hand are affected. Studies of grip strength training have not indicated a negative effect on disease activity after training. Introduction of ultrasound Doppler (USD) to measure increased blood flow induced by inflammation has made it possible to investigate the direct effect on blood supply in the synovium after training. In this case-control study, 24 patients with RA with USD activity in the wrist joint participated. The USD activity was measured by the color fraction (CF) (CF = colored pixels/total number of pixels in ROI). Twenty-four patients were assigned to an 8-week grip strength training program. At baseline and after 8 weeks of training, an USD examination of the wrist joint was performed. In the training group, we measured grip strength and pain in the wrist joint. Six patients withdrew from the training because of pain or change in medication. Eighteen patients served as control group. There was a modest, not significant, decrease in the CF in response to training (1.86%; P = 0.08). Grip strength increased 8.8% after training (P = 0.055). Pain in motion deceased after training (P = 0.04). No difference in the CF was seen between the training and control groups, neither at baseline nor at follow-up (P = 0.82 and P = 0.48). Patients withdrawing from training had a significantly higher CF than the other patients (P > 0.001). The results in this study might indicate that the flow in the synovium assessed by USD is not affected by grip strength training.

  16. Phase Flow Rate Measurements of Annual Flows

    OpenAIRE

    Al-Yarubi, O.S.; Lucas, Gary

    2009-01-01

    The Annular flow regime makes measurement of the total liquid flow rate difficult. It is even more difficult to measure the individual flow rate of either the oil or the water. In a vertical Perspex tube (i.d. = 50 mm) using a newly-designed flow loop in the University of Huddersfield, annular flow was established and different measurements were carried out. One possible on-line measurement technique to achieve the oil volume fraction measurement is an automated bypass...

  17. Increased bone marrow blood flow in polycythemia vera

    Energy Technology Data Exchange (ETDEWEB)

    Lathinen, R.; Lathinen, T.; Hyoedynmaa, S.

    1983-01-01

    Bone marrow blood flow was measured in polycythemia vera, in compensatory and in relative polycythemia with a /sup 133/Xe washout method. In the treated polycythemia vera bone marrow blood flow was significantly increased compared with the age-matched controls. The fraction of blood flow entering the bone and flowing through the hematopoietic marrow was markedly increased in both the untreated and the treated polycythemia vera. Although the number of observations in compensatory and relative polycythemia was small, the results suggest that bone marrow blood flow is not markedly increased in these diseases. The results also suggest that in older patients the simple /sup 133/Xe method may support the diagnosis of polycythemia vera.

  18. Haemodynamic evaluation of the cerebral circulation by periorbital Doppler examination and cerebral blood flow (CBF) measurement in carotid artery disease

    DEFF Research Database (Denmark)

    Sillesen, H; Schroeder, T; Buchardt Hansen, H J

    1988-01-01

    To assess the haemodynamic significance of an internal carotid artery (ICA) stenosis, angiography or direct ultrasound examination should be supplemented by indirect physiologic testing of the collateral circulation. Among the tests proposed, we used the periorbital flow direction, assessed by Do...

  19. Retinal blood flow in diabetic retinopathy.

    OpenAIRE

    Patel, V.; Rassam, S; NEWSOM, R.; Wiek, J; Kohner, E.

    1992-01-01

    OBJECTIVES--(a) To report on the basic parameters of retinal blood flow in a population of diabetic patients with and without retinopathy and non-diabetic controls; (b) to formulate a haemodynamic model for the pathogenesis of diabetic retinopathy from this and other studies. DESIGN--Laser-Doppler velocimetry and computerised image analysis to determine retinal blood flow in a large cross sectional study. SETTING--Diabetic retinopathy outpatient clinic. SUBJECTS--24 non-diabetic controls and ...

  20. Cerebral blood flow volume measurements of the carotid artery and ipsilateral branches using two-dimensional phase-contrast magnetic resonance angiography

    Institute of Scientific and Technical Information of China (English)

    Gang Guo; Yonggui Yang; Weiqun Yang

    2011-01-01

    The optimal velocity encoding of phase-contrast magnetic resonance angiography (PC MRA) in measuring cerebral blood flow volume (BFV) ranges from 60 to 80 cm/s. To verify the accuracy of two-dimensional (2D) PC MRA, the present study localized the region of interest at blood vessels of the neck using PC MRA based on three-dimensional time-of-flight sequences, and the velocity encodingwas set to 80 cm/s. Results of the measurements showed that the error rate was 7.0 ± 6.0%in the estimation of BFV in the internal carotid artery, the external carotid artery and the ipsilateralcommon carotid artery. There was no significant difference, and a significant correlation in BFV between internal carotid artery + external carotid artery and ipsilateral common carotid artery. Inaddition, the BFV of the common carotid artery was correlated with that of the ipsilateral internal carotid artery. The main error was attributed to the external carotid artery and its branches. Therefore,after selecting the appropriate scanning parameters and protocols, 2D PC MRA is more accuratein the determination of BFV in the carotid arteries.

  1. Regional and voxel-wise comparisons of blood flow measurements between dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) and arterial spin labeling (ASL) in brain tumors.

    Science.gov (United States)

    White, Carissa M; Pope, Whitney B; Zaw, Taryar; Qiao, Joe; Naeini, Kourosh M; Lai, Albert; Nghiemphu, Phioanh L; Wang, J J; Cloughesy, Timothy F; Ellingson, Benjamin M

    2014-01-01

    The objective of the current study was to evaluate the regional and voxel-wise correlation between dynamic susceptibility contrast (DSC) and arterial spin labeling (ASL) perfusion magnetic resonance imaging (MRI) measurement of cerebral blood flow (CBF) in patients with brain tumors. Thirty patients with histologically verified brain tumors were evaluated in the current study. DSC-MRI was performed by first using a preload dose of gadolinium contrast, then collecting a dynamic image acquisition during a bolus of contrast, followed by posthoc contrast agent leakage correction. Pseudocontinuous ASL was collected using 30 pairs of tag and control acquisition using a 3-dimensional gradient-echo spin-echo (GRASE) acquisition. All images were registered to a high-resolution anatomical atlas. Average CBF measurements within regions of contrast-enhancement and T2 hyperintensity were evaluated between the two modalities. Additionally, voxel-wise correlation between CBF measurements obtained with DSC and ASL were assessed. Results demonstrated a positive linear correlation between DSC and ASL measurements of CBF when regional average values were compared; however, a statistically significant voxel-wise correlation was only observed in around 30-40% of patients. These results suggest DSC and ASL may provide regionally similar, but spatially different measurements of CBF.

  2. Repeated measurements of cerebral blood flow in the left superior temporal gyrus reveal tonic hyperactivity in patients with auditory verbal hallucinations: A possible trait marker

    Directory of Open Access Journals (Sweden)

    Philipp eHoman

    2013-06-01

    Full Text Available Background: The left superior temporal gyrus (STG has been suggested to play a key role in auditory verbal hallucinations in patients with schizophrenia. Methods: Eleven medicated subjects with schizophrenia and medication-resistant auditory verbal hallucinations and 19 healthy controls underwent perfusion magnetic resonance imaging with arterial spin labeling. Three additional repeated measurements were conducted in the patients. Patients underwent a treatment with transcranial magnetic stimulation (TMS between the first 2 measurements. The main outcome measure was the pooled cerebral blood flow (CBF, which consisted of the regional CBF measurement in the left superior temporal gyrus (STG and the global CBF measurement in the whole brain.Results: Regional CBF in the left STG in patients was significantly higher compared to controls (p < 0.0001 and to the global CBF in patients (p < 0.004 at baseline. Regional CBF in the left STG remained significantly increased compared to the global CBF in patients across time (p < 0.0007, and it remained increased in patients after TMS compared to the baseline CBF in controls (p < 0.0001. After TMS, PANSS (p = 0.003 and PSYRATS (p = 0.01 scores decreased significantly in patients.Conclusions: This study demonstrated tonically increased regional CBF in the left STG in patients with schizophrenia and auditory hallucinations despite a decrease in symptoms after TMS. These findings were consistent with what has previously been termed a trait marker of auditory verbal hallucinations in schizophrenia.

  3. Stochastic modeling for magnetic resonance quantification of myocardial blood flow

    Science.gov (United States)

    Seethamraju, Ravi T.; Muehling, Olaf; Panse, Prasad M.; Wilke, Norbert M.; Jerosch-Herold, Michael

    2000-10-01

    Quantification of myocardial blood flow is useful for determining the functional severity of coronary artery lesions. With advances in MR imaging it has become possible to assess myocardial perfusion and blood flow in a non-invasive manner by rapid serial imaging following injection of contrast agent. To date most approaches reported in the literature relied mostly on deriving relative indices of myocardial perfusion directly from the measured signal intensity curves. The central volume principle on the other hand states that it is possible to derive absolute myocardial blood flow from the tissue impulse response. Because of the sensitivity involved in deconvolution due to noise in measured data, conventional methods are sub-optimal, hence, we propose to use stochastic time series modeling techniques like ARMA to obtain a robust impulse response estimate. It is shown that these methods when applied for the optical estimation of the transfer function give accurate estimates of myocardial blood flow. The most significant advantage of this approach, compared with compartmental tracer kinetic models, is the use of a minimum set of prior assumptions on data. The bottleneck in assessing myocardial blood flow, does not lie in the MRI acquisition, but rather in the effort or time for post processing. It is anticipated that the very limited requirements for user input and interaction will be of significant advantage for the clinical application of these methods. The proposed methods are validated by comparison with mean blood flow measurements obtained from radio-isotope labeled microspheres.

  4. Development of miniaturized mass flow meter for an axial flow blood pump.

    Science.gov (United States)

    Kosaka, Ryo; Maruyama, Osamu; Nishida, Masahiro; Yamane, Takashi

    2007-05-01

    To grasp the conditions of patients and implantable artificial hearts, it is essential to monitor the blood flow rate continuously and noninvasively. However, it is difficult to monitor the pump flow rate in an implantable artificial heart, because the conventional flow meter is too large to implant into the human body, and the flow estimation method is influenced by changes in the blood characteristics and the pump performance. In particular, the power consumption has neither linearity nor uniqueness with respect to the pump flow rate in an axial flow blood pump. In this research, we develop a prototype miniaturized mass flow meter that uses centrifugal force F(c) for discharged patients with an axial flow blood pump. This flow meter measures the F(c) corresponding to the mass flow rate, and implements compensation for static pressure. Because the strain gauges are attached outside of the curved tube, this mass flow meter has no blood contact point, resulting in a compact design. To evaluate the measurement accuracy and the tracking performance, the mass flow meter was compared with the conventional ultrasonic flow meter in a mock-up circulation study. As a result, the measurement error ranging from 0.5 to 5.0 L/min was less than +/-10% with respect to the maximum flow rate. The tracking performance of pulsation flow was approximately equivalent to that of the conventional flow meter. These experiments demonstrated that the prototype miniaturized mass flow meter using F(c) could accurately measure the mass flow rate continuously and noninvasively. PMID:17470214

  5. Collateral sources of costal and crural diaphragmatic blood flow

    International Nuclear Information System (INIS)

    We measured the contribution of aortic, internal mammary, and intercostal arteries to the blood flow to the costal and crural segments of the diaphragm and other respiratory muscles in seven dogs breathing against a fixed inspiratory elastic load. We used radiolabeled microspheres to measure the blood flow with control circulation, occlusion of the aorta distal to the left subclavian artery, combined occlusion of the aorta and both internal mammary arteries, and occlusion of internal mammary arteries alone. With occlusion of the aorta distal to the left subclavian artery, blood flow to the crural diaphragm decreased from 40.3 to 23.5 ml . min-1 X 100 g-1, whereas costal flow did not change significantly (from 41.7 to 38.1 ml . min-1 . 100 g-1). Blood flows to the sternomastoid and scalene muscles (above the occlusion) increased by 200 and 340%, respectively, whereas flows to the other respiratory muscles did not change significantly. Blood flows to organs above the occlusion either remained unchanged or increased, whereas flows to those below the occlusion all decreased. When the internal mammary artery was also occluded, flows to the crural segment decreased further to 12.1 and costal flow decreased to 20.4 ml X min-1 X 100 g-1. Internal mammary arterial occlusion alone in two dogs had no effect on diaphragmatic flow. In conclusion, intercostal collateral vessels are capable of supplying a significant proportion of blood flow to both segments of the diaphragm but the costal segment is better served than the crural segment

  6. Noninvasive methods of measuring bone blood perfusion

    OpenAIRE

    Dyke, J. P.; Aaron, R.K.

    2010-01-01

    Measurement of bone blood flow and perfusion characteristics in a noninvasive and serial manner would be advantageous in assessing revascularization after trauma and the possible risk of avascular necrosis. Many disease states, including osteoporosis, osteoarthritis, and bone neoplasms, result in disturbed bone perfusion. A causal link between bone perfusion and remodeling has shown its importance in sustained healing and regrowth following injury. Measurement of perfusion and permeability wi...

  7. Low cerebral blood flow in hypotensive perinatal distress

    International Nuclear Information System (INIS)

    Hypoxic brain injury is the most important neurological problem in the neonatal period and accounts for more neurological deficits in children than any other lesion. The neurological deficits are notably mental retardation, epilepsy and cerebral palsy. The pathogenesis has hitherto been poorly understood. Arterial hypoxia has been taken as the obvious mechanism but this does not fully explain the patho-anatomical findings. In the present investigation we have examined the arterial blood pressure and the cerebral blood flow in eight infants a few hours after birth. The 133Xe clearance technique was used for the cerebral blood flow measurements. The study confirmed that perinatal distress may be associated with low arterial blood pressure, and it was shown that cerebral blood flow is very low, 20 ml/100 g/min or less, in hypotensive perinatal distress. It is concluded that cerebral ischaemia plays a crucial role in the development of perinatal hypoxic brain injury. (author)

  8. Regional cerebral blood flow in Parkinson's disease measured with N-isopropyl-p-[[sup 123]I]iodoamphetamine (IMP) SPECT

    Energy Technology Data Exchange (ETDEWEB)

    Odano, Ikuo; Nishihara, Mamiko; Hayashi, Hiroko; Higuchi, Shoichi; Sakai, Kunio (Niigata Univ. (Japan). School of Medicine); Ishikawa, Atsushi; Ibayashi, Katsuhiko

    1992-09-01

    N-isopropyl-p-[[sup 123]I]iodoamphetamine (IMP) SPECT studies were performed on 21 patients (13 females; 45-73 yrs) with idiopathic Parkinson's disease (PD) and 10 age-matched normal controls (39-69 yrs). Regional cerebral blood flow (rCBF) was quantitatively measured by the arterial blood sampling method. When compared with normal controls, global CBF, and rCBF in the frontal cortex and in the basal ganglia were reduced 22.1% (p<0.01), 25.0% (p<0.05) and 25.6% (p<0.01), respectively. The reduction of rCBF in the basal ganglia was significantly correlated (p<0.05) with symptoms such as gait disturbance, frozen gait and motor disability score. However, no significant correlation was observed between the severity of dementia and any regional reduction of CBF, including the frontal or parietal cortices. These data show that the severity of dementia in PD may be related to other factors but not with CBF. Quantification of rCBF with [sup 123]I-IMP SPECT imaging is useful for evaluation and follow-up of patients with PD. (author).

  9. Establishing the diffuse correlation spectroscopy signal relationship with blood flow.

    Science.gov (United States)

    Boas, David A; Sakadžić, Sava; Selb, Juliette; Farzam, Parisa; Franceschini, Maria Angela; Carp, Stefan A

    2016-07-01

    Diffuse correlation spectroscopy (DCS) measurements of blood flow rely on the sensitivity of the temporal autocorrelation function of diffusively scattered light to red blood cell (RBC) mean square displacement (MSD). For RBCs flowing with convective velocity [Formula: see text], the autocorrelation is expected to decay exponentially with [Formula: see text], where [Formula: see text] is the delay time. RBCs also experience shear-induced diffusion with a diffusion coefficient [Formula: see text] and an MSD of [Formula: see text]. Surprisingly, experimental data primarily reflect diffusive behavior. To provide quantitative estimates of the relative contributions of convective and diffusive movements, we performed Monte Carlo simulations of light scattering through tissue of varying vessel densities. We assumed laminar vessel flow profiles and accounted for shear-induced diffusion effects. In agreement with experimental data, we found that diffusive motion dominates the correlation decay for typical DCS measurement parameters. Furthermore, our model offers a quantitative relationship between the RBC diffusion coefficient and absolute tissue blood flow. We thus offer, for the first time, theoretical support for the empirically accepted ability of the DCS blood flow index ([Formula: see text]) to quantify tissue perfusion. We find [Formula: see text] to be linearly proportional to blood flow, but with a proportionality modulated by the hemoglobin concentration and the average blood vessel diameter.

  10. Development of a Flexible Implantable Sensor for Postoperative Monitoring of Blood Flow

    OpenAIRE

    Cannata, Jonathan M.; Chilipka, Thomas; Yang, Hao-Chung; Han, Sukgu; Ham, Sung W.; Rowe, Vincent L.; Weaver, Fred A; Shung, K. Kirk; Vilkomerson, David

    2012-01-01

    We have developed a blood flow measurement system using Doppler ultrasound flow sensors fabricated of thin and flexible piezoelectric-polymer films. These flow sensors can be wrapped around a blood vessel and accurately measure flow. The innovation that makes this flow sensor possible is the diffraction-grating transducer. A conventional transducer produces a sound beam perpendicular to its face; therefore, when placed on the wall of a blood vessel, the Doppler shift in the backscattered ultr...

  11. Cerebral blood flow measurement in patients with impaired consciousness: usefulness of {sup 99m}Tc-HMPAO single-photon emission tomography in clinical practice

    Energy Technology Data Exchange (ETDEWEB)

    Chang Chia-Cheng; Kuwana, Nobumasa; Noji, Masato; Tanabe, Yutaka; Koike, Y. [Department of Neurosurgery, Yokohama Minami Kyosai Hospital, Yokohama (Japan); Ikegami, Tadashi [Department of Radiology, Yokohama Minami Kyosai Hospital, Yokohama (Japan)

    1998-09-01

    The relationship between impairment of consciousness and quantitative cerebral blood flow (CBF) was investigated. The mean CBF of the whole brain was measured by the Patlak-plot method using technetium-99m hexamethylpropylene amine oxime single-photon emission tomography ({sup 99m}Tc-HMPAO SPET) in patients with the following diseases: cerebral infarction, intraparenchymal haemorrhage, subarachnoid haemorrhage, brain tumour and cerebral contusion. The clinical symptoms were evaluated according to the severity of impaired consciousness, aphasia and dementia. Four hundred and eighty-five CBF measurements were performed. Patients with alert consciousness showed an age-related decline in mean CBF. Patients with aphasia showed a significant reduction in mean CBF compared with those without aphasia. Impaired consciousness was proportional to reduction in mean CBF regardless of types of pathology, and the size of lesion did not influence the mean CBF. Patients with dementia showed a significant reduction in mean CBF proportional to the severity of dementia. The quantitative measurement of CBF using {sup 99m}Tc-HMPAO SPET is reliable in clinical evaluations. (orig.) With 3 tabs., 10 refs.

  12. Color Doppler measurement of blood flow in the inferior thyroid artery in patients with autoimmune thyroid diseases

    International Nuclear Information System (INIS)

    Purpose: The aim of the study is to find out whether the measurement of peak systolic velocity in the inferior thyroid artery (ITA) is a valuable parameter to differentiate autoimmune thyroid diseases (hyper-, normo- or hypofunctional) and to evaluate the efficacy of medical treatment. Material and methods: The ITA of 31 patients (eight with Graves' disease, 23 with subclinical hypothyroidism) was examined with color Doppler and pulsed Doppler. The final diagnosis was obtained by citology and by hormonal and antibodies assays. The patients were monitorized by ultrasound for a period of 8 months. Results: In all the patients with Graves' disease the peak systolic velocity was always over 150 cm/s, while in other autoimmune thyroiditis the peak systolic velocity was within the normal range, and never exceeding 65 cm/s. In the first group, the measurement taken in the ITA showed also the efficacy of the pharmacological treatment earlier and more reliably than the color Doppler pattern obtained in the parenchyma. Conclusions: The color Doppler measurement of the ITA seems to be a promising technique with low-cost and easy approach. In our experience, the color Doppler of the ITA could have a clinical role in the differential diagnosis of diffuse thyroid diseases and in the follow-up of the Graves' disease during medical treatment

  13. Pulsatile blood flow in Abdominal Aortic Aneurysms

    Science.gov (United States)

    Salsac, Anne-Virginie; Lasheras, Juan C.; Singel, Soeren; Varga, Chris

    2001-11-01

    We discuss the results of combined in-vitro laboratory measurements and clinical observations aimed at determining the effect that the unsteady wall shear stresses and the pressure may have on the growth and eventual rupturing of an Abdominal Aortic Aneurysm (AAA), a permanent bulging-like dilatation occurring near the aortic bifurcation. In recent years, new non-invasive techniques, such as stenting, have been used to treat these AAAs. However, the development of these implants, aimed at stopping the growth of the aneurysm, has been hampered by the lack of understanding of the effect that the hemodynamic forces have on the growth mechanism. Since current in-vivo measuring techniques lack the precision and the necessary resolution, we have performed measurements of the pressure and shear stresses in laboratory models. The models of the AAA were obtained from high resolution three-dimensional CAT/SCANS performed in patients at early stages of the disease. Preliminary DPIV measurements show that the pulsatile blood flow discharging into the cavity of the aneurysm leads to large spikes of pressure and wall shear stresses near and around its distal end, indicating a possible correlation between the regions of high wall shear stresses and the observed location of the growth of the aneurysm.

  14. Hepatic and intestinal blood flow following thermal injury

    International Nuclear Information System (INIS)

    Because cardiac output decreases after burn injuries, investigators have assumed, based upon dye clearance techniques, that hepatic and intestinal blood flow are also decreased following these injuries. Blood flow to the liver, stomach, small intestine, and kidney was determined by the uptake of 201thallium and 125I-labeled fatty acid (para-125I-phenyl-3-methyl pentanoic acid) in a 20% body surface area scald injury that also included plasma volume replacement resuscitation. Uptake of these radioisotopes was determined 15 minutes, 18 hours, and 72 hours after injury. The uptake of the 201thallium and 125I-labeled fatty acid by the gastrointestinal tissues was not statistically different at any of the time periods after comparison of the injured and control (sham-treated) animals. 201Thallium uptake by the kidney was significantly diminished 15 minutes after the burn injury (P less than 0.01). Based on these blood flow measurement techniques, the data suggest that the 20% body surface area scald injury did not alter blood flow to the liver or gastrointestinal tract within the initial 72 hours after the burn injury even though a decrease in renal blood flow was easily detected. These results suggest that the dysfunction of the gastrointestinal system or hepatic system observed after an acute burn injury is not simply the result of hypovolemic shock, which reduces both renal and mesenteric blood flow. These gastrointestinal and hepatic alterations may be related to a factor or factors other than intestinal ischemia

  15. Functional Doppler optical coherence tomography for cortical blood flow imaging

    Science.gov (United States)

    Yu, Lingfeng; Liu, Gangjun; Nguyen, Elaine; Choi, Bernard; Chen, Zhongping

    2010-02-01

    Optical methods have been widely used in basic neuroscience research to study the cerebral blood flow dynamics in order to overcome the low spatial resolution associated with magnetic resonance imaging and positron emission tomography. Although laser Doppler imaging and laser speckle imaging can map out en face cortical hemodynamics and columns, depth resolution is not available. Two-photon microscopy has been used for mapping cortical activity. However, flow measurement requires fluorescent dye injection, which can be problematic. The noninvasive and high resolution tomographic capabilities of optical coherence tomography make it a promising technique for mapping depth resolved cortical blood flow. Here, we present a functional Doppler optical coherence tomography (OCT) imaging modality for quantitative evaluation of cortical blood flow in a mouse model. Fast, repeated, Doppler OCT scans across a vessel of interest were performed to record flow dynamic information with a high temporal resolution of the cardiac cycles. Spectral Doppler analysis of continuous Doppler images demonstrates how the velocity components and longitudinally projected flow-volume-rate change over time, thereby providing complementary temporal flow information to the spatially distributed flow information of Doppler OCT. The proposed functional Doppler OCT imaging modality can be used to diagnose vessel stenosis/blockage or monitor blood flow changes due to pharmacological agents/neuronal activities. Non-invasive in-vivo mice experiments were performed to verify the capabilities of function Doppler OCT.

  16. Effect of blood flow parameters on flow patterns at arterial bifurcations--studies in models.

    Science.gov (United States)

    Liepsch, D W

    1990-01-01

    Atherosclerotic lesions are found primarily at arterial bends and bifurcations. Flow disturbances at these anatomic sites play a major role in atherogenesis. How hemodynamic factors such as vessel geometry, the pulsatile nature of blood flow, vessel wall elasticity and the non-Newtonian flow behavior of blood influence the flow field at these sites must be clarified. We have performed fundamental studies using a birefringent solution in a simplified rigid 90 degree T-bifurcation and pulsatile flow. The velocity distribution was measured with a laser Doppler anemometer. Flow in an elastic abdominal aorta model has been visualized using magnetic resonance imaging. In both flow studies, zones with negative velocity were found. These model measurements demonstrate that no flow parameter can be neglected. Further detailed studies are necessary to examine the interaction between fluid dynamic and cellular surface properties. PMID:2404201

  17. Blood flow characteristics in the aortic arch

    Science.gov (United States)

    Prahl Wittberg, Lisa; van Wyk, Stevin; Mihaiescu, Mihai; Fuchs, Laszlo; Gutmark, Ephraim; Backeljauw, Philippe; Gutmark-Little, Iris

    2012-11-01

    The purpose with this study is to investigate the flow characteristics of blood in the aortic arch. Cardiovascular diseases are associated with specific locations in the arterial tree. Considering atherogenesis, it is claimed that the Wall Shear Stress (WSS) along with its temporal and spatial gradients play an important role in the development of the disease. The WSS is determined by the local flow characteristics, that in turn depends on the geometry as well as the rheological properties of blood. In this numerical work, the time dependent fluid flow during the entire cardiac cycle is fully resolved. The Quemada model is applied to account for the non-Newtonian properties of blood, an empirical model valid for different Red Blood Cell loading. Data obtained through Cardiac Magnetic Resonance Imaging have been used in order to reconstruct geometries of the the aortic arch. Here, three different geometries are studied out of which two display malformations that can be found in patients having the genetic disorder Turner's syndrome. The simulations show a highly complex flow with regions of secondary flow that is enhanced for the diseased aortas. The financial support from the Swedish Research Council (VR) and the Sweden-America Foundation is gratefully acknowledged.

  18. Topical menthol increases cutaneous blood flow.

    Science.gov (United States)

    Craighead, Daniel H; Alexander, Lacy M

    2016-09-01

    Menthol, the active ingredient in several topically applied analgesics, activates transient receptor potential melastatin 8 (TRPM8) receptors on sensory nerves and on the vasculature inducing a cooling sensation on the skin. Ilex paraguariensis is also a common ingredient in topical analgesics that has potential vasoactive properties and may alter the mechanisms of action of menthol. We sought to characterize the microvascular effects of topical menthol and ilex application and to determine the mechanism(s) through which these compounds may independently and combined alter cutaneous blood flow. We hypothesized that menthol would induce vasoconstriction and that ilex would not alter skin blood flow (SkBF). Three separate protocols were conducted to examine menthol and ilex-mediated changes in SkBF. In protocol 1, placebo, 4% menthol, 0.7% ilex, and combination menthol+ilex gels were applied separately to the skin and red cell flux was continuously measured utilizing laser speckle contrast imaging (LSCI). In protocol 2, seven concentrations of menthol gel (0.04%, 0.4%, 1%, 2%, 4%, 7%, 8%) were applied to the skin to model the dose-response curve. In protocol 3, placebo, menthol, ilex, and menthol+ilex gels were applied to skin under local thermal control (34°C) both with and without sensory nerve blockage (topical lidocaine 4%). Post-occlusive reactive hyperemia (PORH) and local heating (42°C) protocols were conducted to determine the relative contribution of endothelium derived hyperpolarizing factors (EDHFs)/sensory nerves and nitric oxide (NO), respectively. Red cell flux was normalized to mean arterial pressure expressed as cutaneous vascular conductance (CVC: flux·mmHg(-1)) in all protocols. Topical menthol application increased SkBF compared to placebo (3.41±0.33 vs 1.1±0.19CVC: peffect, p<0.05) with an ED50 of 1.0%. Similarly, SkBF was increased after menthol application during PORH (3.62±0.29 vs. 2.50±0.21flux·mmHg(-1); p<0.001), but not local heating

  19. Electromechanical Model of Blood Flow in Vessels

    OpenAIRE

    Ivo Cap; Barbora Czippelova

    2008-01-01

    The present paper deals with some theoretical derivations connected with very efficient method of solution of hydrodynamic problems of blood flow in human cardiovascular system. The electromechanical analogy of liquid flow in a tube and electromagnetic wave propagating along an electric transmission line is discussed. We have derived a detailed circuit-like model of an elementary section of the elastic tube with viscose Newtonian liquid. The analogy harmonic current electrical cir...

  20. Structural power flow measurement

    Energy Technology Data Exchange (ETDEWEB)

    Falter, K.J.; Keltie, R.F.

    1988-12-01

    Previous investigations of structural power flow through beam-like structures resulted in some unexplained anomalies in the calculated data. In order to develop structural power flow measurement as a viable technique for machine tool design, the causes of these anomalies needed to be found. Once found, techniques for eliminating the errors could be developed. Error sources were found in the experimental apparatus itself as well as in the instrumentation. Although flexural waves are the carriers of power in the experimental apparatus, at some frequencies longitudinal waves were excited which were picked up by the accelerometers and altered power measurements. Errors were found in the phase and gain response of the sensors and amplifiers used for measurement. A transfer function correction technique was employed to compensate for these instrumentation errors.

  1. Blood flow dynamics in the snake spectacle.

    Science.gov (United States)

    van Doorn, Kevin; Sivak, Jacob G

    2013-11-15

    The eyes of snakes are shielded beneath a layer of transparent integument referred to as the 'reptilian spectacle'. Well adapted to vision by virtue of its optical transparency, it nevertheless retains one characteristic of the integument that would otherwise prove detrimental to vision: its vascularity. Given the potential consequence of spectacle blood vessels on visual clarity, one might expect adaptations to have evolved that mitigate their negative impact. Earlier research demonstrated an adaptation to their spatial layout in only one species to reduce the vessels' density in the region serving the foveal and binocular visual fields. Here, we present a study of spectacle blood flow dynamics and provide evidence of a mechanism to mitigate the spectacle blood vessels' deleterious effect on vision by regulation of blood flow through them. It was found that when snakes are at rest and undisturbed, spectacle vessels undergo cycles of dilation and constriction, such that the majority of the time the vessels are fully constricted, effectively removing them from the visual field. When snakes are presented with a visual threat, spectacle vessels constrict and remain constricted for longer periods than occur during the resting cycles, thus guaranteeing the best possible visual capabilities in times of need. Finally, during the snakes' renewal phase when they are generating a new stratum corneum, the resting cycle is abolished, spectacle vessels remain dilated and blood flow remains strong and continuous. The significance of these findings in terms of the visual capabilities and physiology of snakes is discussed.

  2. Phase flow rate measurements of annular flows

    OpenAIRE

    Al-Yarubi, Qahtan

    2010-01-01

    In the international oil and gas industry multiphase annular flow in pipelines and wells is extremely important, but not well understood. This thesis reports the development of an efficient and cheap method for measuring the phase flow rates in two phase annular and annular mist flow, in which the liquid phase is electrically conducting, using ultrasonic and conductance techniques. The method measures changes in the conductance of the liquid film formed during annular flow and uses these to c...

  3. Effects of aortic irregularities on blood flow.

    Science.gov (United States)

    Prahl Wittberg, Lisa; van Wyk, Stevin; Fuchs, Laszlo; Gutmark, Ephraim; Backeljauw, Philippe; Gutmark-Little, Iris

    2016-04-01

    Anatomic aortic anomalies are seen in many medical conditions and are known to cause disturbances in blood flow. Turner syndrome (TS) is a genetic disorder occurring only in females where cardiovascular anomalies, particularly of the aorta, are frequently encountered. In this study, numerical simulations are applied to investigate the flow characteristics in four TS patient- related aortic arches (a normal geometry, dilatation, coarctation and elongation of the transverse aorta). The Quemada viscosity model was applied to account for the non-Newtonian behavior of blood. The blood is treated as a mixture consisting of water and red blood cells (RBC) where the RBCs are modeled as a convected scalar. The results show clear geometry effects where the flow structures and RBC distribution are significantly different between the aortas. Transitional flow is observed as a jet is formed due to a constriction in the descending aorta for the coarctation case. RBC dilution is found to vary between the aortas, influencing the WSS. Moreover, the local variations in RBC volume fraction may induce large viscosity variations, stressing the importance of accounting for the non-Newtonian effects. PMID:26104133

  4. Frequency encoding in renal blood flow regulation

    DEFF Research Database (Denmark)

    Marsh, Donald J; Sosnovtseva, Olga; Pavlov, Alexey N;

    2005-01-01

    With a model of renal blood flow regulation, we examined consequences of tubuloglomerular feedback (TGF) coupling to the myogenic mechanism via voltage-gated Ca channels. The model reproduces the characteristic oscillations of the two mechanisms and predicts frequency and amplitude modulation...

  5. Frequency encoding in renal blood flow regulation

    DEFF Research Database (Denmark)

    Marsh, D.J.; Sosnovtseva, Olga; Pavlov, A.N.;

    2005-01-01

    With a model of renal blood flow regulation, we examined consequences of tubuloglomerular feedback (TGF) coupling to the myogenic mechanism via voltage-gated Ca channels. The model reproduces the characteristic oscillations of the two mechanisms and predicts frequency and amplitude modulation of ...

  6. Xenon computed tomographic blood flow mapping

    International Nuclear Information System (INIS)

    Xenon CT flow information appears to be clinically useful in the diagnosis and management of a broad spectrum of clinical disorders. It also appears to be a useful tool for the experimental study of the cerebral circulation, with recent work also extending to application to the study of solid abdominal organs. The authors therefore found xenon CT CBF mapping to be a useful new blood flow methodology and are of the opinion that as CT technology improves, one will be able to obtain still better flow information with less accompanying radiation exposure and/or a reduction in the level of xenon inhalation required

  7. Cerebral blood flow measured by arterial-spin labeling MRI: A useful biomarker for characterization of minimal hepatic encephalopathy in patients with cirrhosis

    International Nuclear Information System (INIS)

    Purpose: To investigate the role of arterial-spin labeling (ASL) MRI to non-invasively characterize the patterns of cerebral blood flow (CBF) changes in cirrhotic patients and to assess the potential of ASL MRI to characterize minimal hepatic encephalopathy (MHE). Materials and methods: This study was approved by the local ethics committee, and written informed consent was obtained from all participants. Thirty six cirrhosis patients without overt hepatic encephalopathy (16 MHE patients and 20 non hepatic encephalopathy (non-HE) patients) and 25 controls underwent ASL MRI, and CBF was measured for each subject. One-way ANOCOVA test with age and gender as covariences was used to compare CBF difference among three groups, and post hoc analysis was performed between each two groups. Region-based correlation analysis was applied between Child–Pugh score, venous blood ammonia level, neuropsychological tests and CBF values in cirrhosis patients. Receiver operator characteristic (ROC) analysis was used for assessing CBF measurements in ASL MRI to differentiate MHE from non-HE patients. Results: The gray matter CBF of MHE patients (71.09 ± 11.88 mL min−1 100 g−1) was significantly higher than that of non-HE patients (55.28 ± 12.30 mL min−1 100 g−1, P < 0.01) and controls (52.09 ± 9.27 mL min−1 100 g−1, P < 0.001). Voxel-wise ANOCOVA results showed that CBFs were significantly different among three groups in multiple gray matter areas (P < 0.05, Bonferroni corrected). Post hoc comparisons showed that CBF of these brain regions was increased in MHE patients compared with controls and non-HE patients (P < 0.05, Bonferroni corrected). CBF of the right putamen was of the highest sensitivity (93.8%) and moderate specificity (75.0%) for characterization of MHE when using the cutoff value of 50.57 mL min−1 100 g−1. CBFs in the bilateral median cingulate gyri, left supramarginal gyrus, right angular gyrus, right heschl gyrus and right superior temporal gyrus

  8. Cerebral blood flow measured by arterial-spin labeling MRI: A useful biomarker for characterization of minimal hepatic encephalopathy in patients with cirrhosis

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Gang [Department of Medical Imaging, Jinling Hospital, Clinical School of Medical College, Nanjing University, Nanjing, Jiangsu, 210002 (China); College of Civil Aviation, Nanjing University of Aeronautics and Astronautics, Nanjing, Jiangsu, 210016 (China); Zhang, Long Jiang, E-mail: kevinzhlj@163.com [Department of Medical Imaging, Jinling Hospital, Clinical School of Medical College, Nanjing University, Nanjing, Jiangsu, 210002 (China); Zhong, Jianhui [Department of Imaging Sciences, University of Rochester School of Medicine and Dentistry, Box648, 601 Elmwood Avenue, Rochester, NY 14642-8648 (United States); Wang, Ze [Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, 3900 Chestnut St., Philadelphia, PA 19104 (United States); Qi, Rongfeng; Shi, Donghong [Department of Medical Imaging, Jinling Hospital, Clinical School of Medical College, Nanjing University, Nanjing, Jiangsu, 210002 (China); Lu, Guang Ming, E-mail: cjr.luguangming@vip.163.com [Department of Medical Imaging, Jinling Hospital, Clinical School of Medical College, Nanjing University, Nanjing, Jiangsu, 210002 (China)

    2013-11-01

    Purpose: To investigate the role of arterial-spin labeling (ASL) MRI to non-invasively characterize the patterns of cerebral blood flow (CBF) changes in cirrhotic patients and to assess the potential of ASL MRI to characterize minimal hepatic encephalopathy (MHE). Materials and methods: This study was approved by the local ethics committee, and written informed consent was obtained from all participants. Thirty six cirrhosis patients without overt hepatic encephalopathy (16 MHE patients and 20 non hepatic encephalopathy (non-HE) patients) and 25 controls underwent ASL MRI, and CBF was measured for each subject. One-way ANOCOVA test with age and gender as covariences was used to compare CBF difference among three groups, and post hoc analysis was performed between each two groups. Region-based correlation analysis was applied between Child–Pugh score, venous blood ammonia level, neuropsychological tests and CBF values in cirrhosis patients. Receiver operator characteristic (ROC) analysis was used for assessing CBF measurements in ASL MRI to differentiate MHE from non-HE patients. Results: The gray matter CBF of MHE patients (71.09 ± 11.88 mL min{sup −1} 100 g{sup −1}) was significantly higher than that of non-HE patients (55.28 ± 12.30 mL min{sup −1} 100 g{sup −1}, P < 0.01) and controls (52.09 ± 9.27 mL min{sup −1} 100 g{sup −1}, P < 0.001). Voxel-wise ANOCOVA results showed that CBFs were significantly different among three groups in multiple gray matter areas (P < 0.05, Bonferroni corrected). Post hoc comparisons showed that CBF of these brain regions was increased in MHE patients compared with controls and non-HE patients (P < 0.05, Bonferroni corrected). CBF of the right putamen was of the highest sensitivity (93.8%) and moderate specificity (75.0%) for characterization of MHE when using the cutoff value of 50.57 mL min{sup −1} 100 g{sup −1}. CBFs in the bilateral median cingulate gyri, left supramarginal gyrus, right angular gyrus, right

  9. Cerebral blood flow velocity changes after rapid administration of surfactant.

    OpenAIRE

    Cowan, F.; Whitelaw, A; D. Wertheim; Silverman, M

    1991-01-01

    A computer linked Doppler system was used to make continuous measurements of cerebral blood flow velocity (CBFV) from the middle cerebral artery, mean arterial blood pressure (MAP) from the umbilical artery, and heart rate before, during, and for 20 minutes after the endotracheal administration of 200 mg/kg of porcine surfactant in 10 preterm infants with respiratory distress syndrome. Within two minutes of surfactant administration, there was a median fall of 6 mm Hg (15%) fall in MAP and 36...

  10. Verapamil buffering effect on the abrupt elevation in blood pressure, linkage with microcirculatory blood flow.

    Science.gov (United States)

    Gmitrov, J

    2008-01-01

    1 We studied the effects of verapamil on sudden elevation in blood pressure, microcirculation and arterial baroreflex sensitivity (BRS). 2 Thirty experiments (10 controls and 20 with verapamil) were performed in rabbits sedated using pentobarbital infusion (5 mg kg(-1) h(-1)). 3 BRS, mean femoral artery blood pressure (MAP), heart rate (HR) and ear lobe skin microcirculatory blood flow, estimated using microphotoelectric plethysmography (MPPG), were simultaneously measured during 30 min of verapamil infusion (20 mug kg(-1) min(-1)). BRS was assessed from HR and MAP responses to intravenous phenylephrine (Ph) and by power spectral analysis using transfer function (TF) from MAP to the HR (BRS(Ph,TF)). 4 Verapamil significantly increased microcirculatory blood flow, and decreased BRS(Ph,TF) and phenylephrine-induced abrupt elevation in MAP (MAP(AE)). 5 A significant inverse correlation was found between verapamil-induced changes in MAP(AE), BRS and in microcirculatory blood flow, measured before phenylephrine blood pressure ramps (DeltaMAP(AE) with DeltaBRS(TF), r = -0.47, P < 0.036; DeltaMAP(AE) with DeltaMPPG, r = -0.49, P < 0.025). 6 These results suggest involvement of the arterial baroreflex and vascular blood pressure-buffering mechanisms, their enhancement by verapamil, and thus a potential benefit of verapamil in cardiovascular conditions where patients present with abrupt high elevations in blood pressure. PMID:18598288

  11. Modeling of blood flow in arterial trees.

    Science.gov (United States)

    Anor, Tomer; Grinberg, Leopold; Baek, Hyoungsu; Madsen, Joseph R; Jayaraman, Mahesh V; Karniadakis, George E

    2010-01-01

    Advances in computational methods and medical imaging techniques have enabled accurate simulations of subject-specific blood flows at the level of individual blood cell and in complex arterial networks. While in the past, we were limited to simulations with one arterial bifurcation, the current state-of-the-art is simulations of arterial networks consisting of hundreds of arteries. In this paper, we review the advances in methods for vascular flow simulations in large arterial trees. We discuss alternative approaches and validity of various assumptions often made to simplify the modeling. To highlight the similarities and discrepancies of data computed with different models, computationally intensive three-dimensional (3D) and inexpensive one-dimensional (1D) flow simulations in very large arterial networks are employed. Finally, we discuss the possibilities, challenges, and limitations of the computational methods for predicting outcomes of therapeutic interventions for individual patients. PMID:20836052

  12. Measurement of blood flow in the superior sagittal sinus in healthy volunteers, and in patients with normal pressure hydrocephalus and idiopathic intracranial hypertension with phase-contrast cine MR imaging

    DEFF Research Database (Denmark)

    Gideon, P; Thomsen, C; Gjerris, F;

    1996-01-01

    PURPOSE: To measure blood flow and velocity in the superior sagittal ++sinus. MATERIAL AND METHODS: MR velocity mapping was used to examine 14 healthy volunteers, 15 patients with normal pressure hydrocephalus (NPH), 3 patients with high pressure hydrocephalus (HPH), and 11 patients with idiopath...

  13. Arterial secondary blood flow patterns visualized with vector flow ultrasound

    DEFF Research Database (Denmark)

    Pedersen, Mads Møller; Pihl, Michael Johannes; Hansen, Jens Munk;

    2011-01-01

    This study presents the first quantification and visualisation of secondary flow patterns with vector flow ultrasound. The first commercial implementation of the vector flow method Transverse Oscillation was used to obtain in-vivo, 2D vector fields in real-time. The hypothesis of this study...... was that the rotational direction is constant within each artery. Three data sets of 10 seconds were obtained from three main arteries in healthy volunteers. For each data set the rotational flow patterns were identified during the diastole. Each data set contains a 2D vector field over time and with the vector angles...... and velocity magnitudes the blood flow patterns were visualised with streamlines in Matlab (Mathworks, Natick, MA, USA). The rotational flow was quantified by the angular frequency for each cardiac cycle, and the mean rotational frequencies and standard deviations were calculated for the abdominal aorta f-1...

  14. Study on a Digital Doppler Ultrasonic Blood Flow Measurement System%全数字超声多普勒血流测量系统研究

    Institute of Scientific and Technical Information of China (English)

    齐敏超; 高上凯

    2012-01-01

    The conventional Doppler ultrasonic blood flow measurement systems use analog circuits to complete the signal acquisition and processing. Such instruments are susceptible to external electromagnetic interference,environment temperature changes and other factors,and it's difficult to implement modern signal processing algorithms to achieve more advanced detections,such as multi-depth detection,power M-mode Doppler and coded excitation. In this paper,a digital Doppler ultrasonic blood flow signal acquisition and processing system was designed,combined with the classic " autocorrelation technology" to achieve multi-depth detection and power M-mode Doppler. And the axial resolution of the system based on the 2-cycle base 13-chip Barker coded excitation was much better than the conventional method. The feasibility of the system was proved by the phantom test. In addition,the human cerebral artery measurement showed that the system could display the blood information on the path of the ultasound wave,and it was useful for the vessel positioning and identification.%传统超声多普勒血流测量仪器使用模拟电路来完成信号采集与解调处理,此类系统容易受外界电磁环境、温度变化等因素的干扰,也难以运用现代信号处理技术来实现更高级的检测功能,例如多深度检测、功率M型多普勒血流成像以及编码激励成像等.本研究设计了一种全数字的超声多普勒血流信号采集处理系统,结合经典的自相关技术,实现了多深度检测和功率M型多普勒血流成像,并采用2周期基础码调制的13位Barker码编码激励方法,得到远高于传统方法的轴向空间分辨率.为验证该系统的有效性,首先利用该系统对多普勒体模进行检测实验研究,证明该系统能有效提高轴向空间分辨率;然后通过对大脑中动脉、前动脉血流检测,表明该系统可以显示出超声波发射方向上整个深度的血流信息,有利于血管的定位和识别.

  15. Ambulatory measurement of nocturnal fluctuations in subcutaneous blood flow rate in the lower leg of man during 12-h periods with the portable CdTe(Cl) detector. Methodological considerations.

    Science.gov (United States)

    Sindrup, J H; Kastrup, J; Jørgensen, B; Bülow, J; Tønnesen, K H

    1991-07-01

    Possible sources of error during long-term measurements of subcutaneous blood flow rate with the portable CdTe(Cl) detector system were ruled out in the present study. Local blood flow rates were recorded in the lower legs of normal human subjects by means of the 133Xe wash-out technique. A good correlation was found between the portable CdTe(Cl) and stationary NaI(Tl) detector systems both prior to (r = 0.88, P less than 0.0001) and after (r = 0.68, P = 0.07) day over night (12 h) measurements. Identical post-ischaemic reactive hyperaemia could be demonstrated by both detector systems 12 h after the application of the isotope depot. This indicates that blood flow rates and vascular reactivity can be measured over 12 h by the portable CdTe(Cl) detector. Identical results were obtained during the 12-h measurements performed with the portable CdTe(Cl) detector attached directly to the skin surface and with the detector elevated above the skin surface. Therefore, geometrical changes were without any influence on our measurements. We conclude that measurements of subcutaneous blood flow rates in the lower leg of human subjects can be performed under out-patients conditions by means of the 133Xe wash-out technique and portable CdTe(Cl) detectors. A skin area greater than or equal to 4 cm should be labelled by means of the atraumatic, epicutaneous labelling technique and the detector attached directly to the skin surface with a single layer of a 20-micron thick gas-tight Mylar membrane interposed between the skin surface and the detector. The investigation of the subcutaneous blood flow rate should not be initiated until at least 90 min after labelling.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1914438

  16. Ocular Blood Flow and Normal Tension Glaucoma

    Directory of Open Access Journals (Sweden)

    Ning Fan

    2015-01-01

    Full Text Available Normal tension glaucoma (NTG is known as a multifactorial optic neuropathy characterized by progressive retinal ganglion cell death and glaucomatous visual field loss, even though the intraocular pressure (IOP does not exceed the normal range. The pathophysiology of NTG remains largely undetermined. It is hypothesized that the abnormal ocular blood flow is involved in the pathogenesis of this disease. A number of evidences suggested that the vascular factors played a significant role in the development of NTG. In recent years, the new imaging techniques, fluorescein angiography, color Doppler imaging (CDI, magnetic resonance imaging (MRI, and laser speckle flowgraphy (LSFG, have been used to evaluate the ocular blood flow and blood vessels, and the impaired vascular autoregulation was found in patients with NTG. Previous studies showed that NTG was associated with a variety of systemic diseases, including migraine, Alzheimer’s disease, primary vascular dysregulation, and Flammer syndrome. The vascular factors were involved in these diseases. The mechanisms underlying the abnormal ocular blood flow in NTG are still not clear, but the risk factors for glaucomatous optic neuropathy likely included oxidative stress, vasospasm, and endothelial dysfunction.

  17. Inner ocular blood flow responses to an acute decrease in blood pressure in resting humans

    International Nuclear Information System (INIS)

    Whether inner ocular vessels have an autoregulatory response to acute fluctuations in blood pressure is unclear. We tried to examine the validity of acute hypotension elicited by thigh-cuff release as to assess the dynamic autoregulation in the ocular circulation. Blood flow velocity in the superior nasal and inferior temporal retinal arterioles, and in the retinal and choroidal vasculature were measured with the aid of laser speckle flowgraphy before and immediately after an acute decrease in blood pressure in 20 healthy subjects. Acute hypotension was induced by a rapid release of bilateral thigh occlusion cuffs that had been inflated to 220 mmHg for 2 min. The ratio of the relative change in retinal and choroidal blood flow velocity to the relative change in mean arterial blood pressure (MAP) was calculated. Immediately after cuff release, the MAP and blood flows in the all ocular target vessels decreased significantly from the baseline values obtained before thigh-cuff release. The ratio of the relative change in inner ocular blood flow velocity to that in the MAP exceeded 1% / %mmHg. An explicit dynamic autoregulation in inner ocular vessels cannot be demonstrated in response to an acute hypotension induced by the thigh-cuff release technique. (paper)

  18. Blood Flow Restricted Exercise and Vascular Function

    Directory of Open Access Journals (Sweden)

    Masahiro Horiuchi

    2012-01-01

    Full Text Available It is established that regular aerobic training improves vascular function, for example, endothelium-dependent vasodilatation and arterial stiffness or compliance and thereby constitutes a preventative measure against cardiovascular disease. In contrast, high-intensity resistance training impairs vascular function, while the influence of moderate-intensity resistance training on vascular function is still controversial. However, aerobic training is insufficient to inhibit loss in muscular strength with advancing age; thus, resistance training is recommended to prevent sarcopenia. Recently, several lines of study have provided compelling data showing that exercise and training with blood flow restriction (BFR leads to muscle hypertrophy and strength increase. As such, BFR training might be a novel means of overcoming the contradiction between aerobic and high-intensity resistance training. Although it is not enough evidence to obtain consensus about impact of BFR training on vascular function, available evidences suggested that BFR training did not change coagulation factors and arterial compliance though with inconsistence results in endothelial function. This paper is a review of the literature on the impact of BFR exercise and training on vascular function, such as endothelial function, arterial compliance, or other potential factors in comparison with those of aerobic and resistance training.

  19. Regional cerebral blood flow in neuropediatrics

    International Nuclear Information System (INIS)

    Single photon emission computed tomography can effectively and non-invasively measure regional blood flow. Mostly used 99mTc-HMPAO is a safe brain imaging agent for pediatric applications. The radiation dose is acceptable. Knowledge of the normal rCBF pattern, including normal asymmetries and variations due to age, is necessary prerequisite for the evaluation and reporting of the results of 99mTc-HMPAO brain SPECT studies in clinical practice. The interpretation of he rCBF study in a child requires knowledge of normal brain maturation. The aim of the present review is to focus on the contribution to clinical developmental neurology of SPECT The clinical use of SPECT in developmental neurology are epilepsy, brain death, acute neurological loss including stroke, language disorders, cerebral palsy, high-risk neonates, hypertension due to renovascular disease, traumatic brain injury, migraine, anorexia nervosa, autism, Gilles de la Tourette syndrome, attention deficit disorder-hyperactivity, and monitoring therapy. Sedation is not routinely used, rather each child is evaluated. However, drug sedation is mandatory in some uncooperative children. (author)

  20. Synthetic Capillaries to Control Microscopic Blood Flow

    Science.gov (United States)

    Sarveswaran, K.; Kurz, V.; Dong, Z.; Tanaka, T.; Penny, S.; Timp, G.

    2016-02-01

    Capillaries pervade human physiology. The mean intercapillary distance is only about 100 μm in human tissue, which indicates the extent of nutrient diffusion. In engineered tissue the lack of capillaries, along with the associated perfusion, is problematic because it leads to hypoxic stress and necrosis. However, a capillary is not easy to engineer due to its complex cytoarchitecture. Here, it is shown that it is possible to create in vitro, in about 30 min, a tubular microenvironment with an elastic modulus and porosity consistent with human tissue that functionally mimicks a bona fide capillary using “live cell lithography”(LCL) to control the type and position of cells on a composite hydrogel scaffold. Furthermore, it is established that these constructs support the forces associated with blood flow, and produce nutrient gradients similar to those measured in vivo. With LCL, capillaries can be constructed with single cell precision—no other method for tissue engineering offers such precision. Since the time required for assembly scales with the number of cells, this method is likely to be adapted first to create minimal functional units of human tissue that constitute organs, consisting of a heterogeneous population of 100-1000 cells, organized hierarchically to express a predictable function.

  1. Velocity estimation using synthetic aperture imaging [blood flow

    OpenAIRE

    Nikolov, Svetoslav; Jensen, Jørgen Arendt

    2001-01-01

    Presented an approach for synthetic aperture blood flow ultrasound imaging. Estimates with a low bias and standard deviation can be obtained with as few as eight emissions. The performance of the new estimator is verified using both simulations and measurements. The results demonstrate that a fully functioning synthetic aperture scanner can be made

  2. Patterns of regional cerebral blood flow in acute stroke

    DEFF Research Database (Denmark)

    Olsen, T S; Skriver, E B

    1981-01-01

    In a consecutive group of 56 stroke patients the regional cerebral blood flow was measured within 84 hours after stroke. A 254 multidetector scintillation camera and the intracarotid Xenon-133 injection method was used to study rCBF. Typical rCBF-patterns are described and compared to the findings...

  3. Velocity estimation using synthetic aperture imaging [blood flow

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Jensen, Jørgen Arendt

    2001-01-01

    Presented an approach for synthetic aperture blood flow ultrasound imaging. Estimates with a low bias and standard deviation can be obtained with as few as eight emissions. The performance of the new estimator is verified using both simulations and measurements. The results demonstrate that a fully...

  4. Superficial microcirculation flow measurement using polarized light

    Science.gov (United States)

    Wu, Jiwei; Morgan, S. P.; Xiao, Yunshi

    2008-12-01

    Depth discrimination of polarized light is used in investigating laser Doppler measurement of the superficial microcirculation in tissue. Using polarization Monte Carlo simulation, temporal point spread function and power spectral distribution of backscattered polarization remaining light firstly are used to prove polarized light to be valid in measuring moving blood cell perfusion and mean flow velocity. Then simulation of layered medium model demonstrate that relationships between blood flow perfusion and mean frequency shift are linear to medium flowing velocity, and the Doppler shift information in polarization remaining light mainly comes from lower layer medium up to about 14 times of mean free path (MFP) of medium investigated and can be considered that Doppler effects come only from lower layer of the medium. Simulations in three-layer tissue model show that moving blood cell perfusion and mean blood cell moving velocity calculated from polarization remaining are much more sensitive to lower layer flow velocity variation, and more irrelevant to deeper layer flow rate fluctuations, that further confirms Doppler measurement from polarization remaining light to be effective for superficial microcirculation in tissue. Factors affecting Laser Doppler measurement like medium absorption, percentage of moving particles in blood detector size are discussed.

  5. Uteroplacental blood flow during alkalosis in the sheep

    International Nuclear Information System (INIS)

    Uteroplacental blood flow was measured by the radioactive-microsphere technique in eight near-term pregnant ewes during a normal control period and during maternal metabolic alkalosis. All measurements were made on awake, unanesthetized animals. Alkalosis, defined for this study as an arterial pH of 7.60 or greater, was produced by the oral administration of sodium bicarbonate, 3 g/kg body wt. The rise in pH thus produced was unaccompanied by significant changes in systemic arterial blood pressure and cardiac output, while maternal arterial P/sub CO2/ rose slightly from control levels. Cotyledonary blood flow declined from a control value of 1.177 ml/min to 1.025 ml/min during alkalosis. This decline of 13 percent in cotyledonary blood flow is significant (P less than 0.02). Blood flow to the remaining uterine tissue, or noncotyledonary uterus, did not change with alkalosis, being maintained at approximately 195 ml/min. It is concluded that maternal alkalosis, unaccompanied by major changes in P /sub CO2/ and systemic arterial pressure, causes a small increase in the resistance of the uteroplacental circulation

  6. Effects of intramedullary reaming and nailing on blood flow in rat femora

    Energy Technology Data Exchange (ETDEWEB)

    Indrekvam, K.; Lekven, J.; Engesaeter, L.B.; Langeland, N. (University of Bergen, Surgical Research Laboratory, Orthopedic Division, Haukeland Hospital, Bergen (Norway))

    1992-01-01

    The right femur in 40 rats was reamed, and in 40 others it was additionally nailed. Analysis of bone blood flow was performed by the distribution of radiolabeled microspheres at different postoperative time intervals. Blood-flow measurements were accompanied by analyses of hydroxyproline and calcium contents. Immediately after reaming, the blood flow of the diaphyseal part of the femur was reduced to approximately one third of that of the intact femur, whereas the contents of hydroxyproline and calcium were reduced by 10 percent. Within 1 week, the blood flow was normal. This study provides evidence that the presence of a nail does not interfere with the restoration of bone blood flow. Restoration of blood flow in bone apparently is a rapid process. The replacement of hydroxyproline and calcium contents seemed to be linked to flow, as no increase in these constituents were found until the blood flow had approximated the level of the intact femur. (au).

  7. Glial and neuronal control of brain blood flow

    DEFF Research Database (Denmark)

    Attwell, David; Buchan, Alastair M; Charpak, Serge;

    2010-01-01

    Blood flow in the brain is regulated by neurons and astrocytes. Knowledge of how these cells control blood flow is crucial for understanding how neural computation is powered, for interpreting functional imaging scans of brains, and for developing treatments for neurological disorders. It is now...... recognized that neurotransmitter-mediated signalling has a key role in regulating cerebral blood flow, that much of this control is mediated by astrocytes, that oxygen modulates blood flow regulation, and that blood flow may be controlled by capillaries as well as by arterioles. These conceptual shifts...... in our understanding of cerebral blood flow control have important implications for the development of new therapeutic approaches....

  8. Feasibility of patient specific aortic blood flow CFD simulation.

    Science.gov (United States)

    Svensson, Johan; Gårdhagen, Roland; Heiberg, Einar; Ebbers, Tino; Loyd, Dan; Länne, Toste; Karlsson, Matts

    2006-01-01

    Patient specific modelling of the blood flow through the human aorta is performed using computational fluid dynamics (CFD) and magnetic resonance imaging (MRI). Velocity patterns are compared between computer simulations and measurements. The workflow includes several steps: MRI measurement to obtain both geometry and velocity, an automatic levelset segmentation followed by meshing of the geometrical model and CFD setup to perform the simulations follwed by the actual simulations. The computational results agree well with the measured data. PMID:17354898

  9. Quantitative myocardial blood flow with Rubidium-82 PET

    DEFF Research Database (Denmark)

    Hagemann, Christoffer E; Ghotbi, Adam A; Kjær, Andreas;

    2015-01-01

    Positron emission tomography (PET) allows assessment of myocardial blood flow in absolute terms (ml/min/g). Quantification of myocardial blood flow (MBF) and myocardial flow reserve (MFR) extend the scope of conventional semi-quantitative myocardial perfusion imaging (MPI): e.g. in 1) identificat......Positron emission tomography (PET) allows assessment of myocardial blood flow in absolute terms (ml/min/g). Quantification of myocardial blood flow (MBF) and myocardial flow reserve (MFR) extend the scope of conventional semi-quantitative myocardial perfusion imaging (MPI): e.g. in 1...... pretest probability of CAD can support the clinical decision-making in treatment of CAD patients as a complementary tool to the invasive coronary angiography (CAG). Recently, several studies have proven Rubidium-82 ((82)Rb) PET's long-term prognostic value by a significant association between compromised...... global MFR and major adverse cardiovascular events (MACE), and together with new diagnostic possibilities from measuring the longitudinal myocardial perfusion gradient, cardiac (82)Rb PET faces a promising clinical future. This article reviews current evidence on quantitative (82)Rb PET's ability...

  10. Caffeine reduces myocardial blood flow during exercise.

    Science.gov (United States)

    Higgins, John P; Babu, Kavita M

    2013-08-01

    Caffeine consumption has been receiving increased interest from both the medical and lay press, especially given the increased amounts now available in energy products. Acute ingestion of caffeine usually increases cardiac work; however, caffeine impairs the expected proportional increase in myocardial blood flow to match this increased work of the heart, most notably during exercise. This appears to be mainly due to caffeine's effect on blocking adenosine-induced vasodilatation in the coronary arteries in normal healthy subjects. This review summarizes the available medical literature specifically relating to pure caffeine tablet ingestion and reduced exercise coronary blood flow, and suggests possible mechanisms. Further studies are needed to evaluate this effect for other common caffeine-delivery systems, including coffee, energy beverages, and energy gels, which are often used for exercise performance enhancement, especially in teenagers and young athletes. PMID:23764265

  11. Change of cerebral blood flow distribution and vascular reserver according to age in Koreans measured by Tc-99m HMPAO brain SPECT

    International Nuclear Information System (INIS)

    The aim of this study was to evaluate the normal values of regional cerebral blood flow (rCBF) and cerebrovascular reserve (CVR) in normal children to aged volunteers using Tc-99m HMPAO. Thirty four right-handed normal volunteers (20 males, 14 females, mean age 40.3±24.9 years, range 4 to 82 years) were underwent rest/acetazolamide (ACZ) brain SPECT using Tc-99m HMPAO and the sequential injection and subtraction method. rCBF was estimated on the basis of a semiquantitative approach by means of right/left ratio, region/cerebellum and region to whole brain ratios in frontal, parietal, temporal, and occipital lobes, basal ganglia, thalami, and cerebellum. CVR was measured by means of % perfusion increase calculated as % mean count change compared to rest rCBF in each regions. Mean values of right to left ratios range from 1.004 to 1.018. rCBF was highest in cerebellum and lowest in basal ganglia and thalami. Frontal and temporal rCBF decreased while occipital and thalamic rCBF increased according to age. No sexual difference of rCBF was noted. Mean CVR was 29.9±12.9%. Mean CVR significantly increased to late teens, and declined thereafter. After 6th decade, CVR in both frontal lobes, left parietal lobe and right basal ganglia decreased significantly with advancing age. There was no sexual difference of CVR. Quantitative assessment of CVR was possible by ACZ Tc-99m MHPAO brain SPECT. It revealed that rCBF and CVR changed according to age in normal Korean volunteers. There was no sexual difference

  12. Study Of Topical Anti-Inflammatory Potency And Clinical Efficacy Of Formulations Of Mometasone And Betamethasone By Cutaneous Blood Flow Measurements In Psoriatic Patients Using Laser Doppler Velocimetry

    Directory of Open Access Journals (Sweden)

    Mulekar S. V

    1997-01-01

    Full Text Available Laser Doppier Velocimetry (LDV was used to measure cutaneous blood flow (CBF in psoriatic skin lesions to assess the effect of once daily application of Mometasone furoate (MF in a base claimed to possess a “reservoir” effect, as against Betamethasone-17-valarate (BV in a conventional cream base, applied twice daily, for 4 weeks. Bilaterally symmetrical active lesions were studied in 10 psoriatics, at baseline and at the end of 2 and 4 weeks’ treatment. The formulations were also evaluated for topical anti-inflammatory potency in terms of their ability to inhibit the Post-Ischaemic-Reactive-Hyperaemic-Response (PIRHR induced on normal uninvolved skin treated under occlusion. The lesions were also assessed subjectively for clinical Psoriatic Hyperaemia Index (PHI = CBF on lesions/CBF on uninvolved skin: 8.42 + 1.74 & 10.13 + 1.70 correlating with high CPI (9 + 0.50 & 9.1 + 0.51. During treatment with MF or BV, the lesions resolved rapidly, with a concomitant decrease in PHI and CPI (Week 2 : PHI = 3.40 + 0.46 & 5.19 + 1.65, CPI = 4.15 + 0.86& 5.20 + 0.87 and Week 4 : PHI = 1.99 + 0.23 & 2.81 + 0.74 CPI = 2.00 + 0.50 & 2.88 + 0.72 respectively. The two formulations Inhibited PIRHR to same extent (auc/min: Control = 1871 + 399.22, MF = 536.11 + 153.34 & BV = 567.5 + 110.76, indicating equal potency. The results show that pharmaceutical factor such as vehicle can significantly influence the clinical efficacy of corticoids.

  13. Blood flow-restricted exercise in space

    OpenAIRE

    Hackney, Kyle J; Everett, Meghan; Scott, Jessica M; Ploutz-Snyder, Lori

    2012-01-01

    Prolonged exposure to microgravity results in chronic physiological adaptations including skeletal muscle atrophy, cardiovascular deconditioning, and bone demineralization. To attenuate the negative consequences of weightlessness during spaceflight missions, crewmembers perform moderate- to high-load resistance exercise in conjunction with aerobic (cycle and treadmill) exercise. Recent evidence from ground-based studies suggests that low-load blood flow-restricted (BFR) resistance exercise tr...

  14. Red blood cell in simple shear flow

    Science.gov (United States)

    Chien, Wei; Hew, Yayu; Chen, Yeng-Long

    2013-03-01

    The dynamics of red blood cells (RBC) in blood flow is critical for oxygen transport, and it also influences inflammation (white blood cells), thrombosis (platelets), and circulatory tumor migration. The physical properties of a RBC can be captured by modeling RBC as lipid membrane linked to a cytoskeletal spectrin network that encapsulates cytoplasm rich in hemoglobin, with bi-concave equilibrium shape. Depending on the shear force, RBC elasticity, membrane viscosity, and cytoplasm viscosity, RBC can undergo tumbling, tank-treading, or oscillatory motion. We investigate the dynamic state diagram of RBC in shear and pressure-driven flow using a combined immersed boundary-lattice Boltzmann method with a multi-scale RBC model that accurately captures the experimentally established RBC force-deformation relation. It is found that the tumbling (TU) to tank-treading (TT) transition occurs as shear rate increases for cytoplasm/outer fluid viscosity ratio smaller than 0.67. The TU frequency is found to be half of the TT frequency, in agreement with experiment observations. Larger viscosity ratios lead to the disappearance of stable TT phase and unstable complex dynamics, including the oscillation of the symmetry axis of the bi-concave shape perpendicular to the flow direction. The dependence on RBC bending rigidity, shear modulus, the order of membrane spectrin network and fluid field in the unstable region will also be discussed.

  15. Sympathetic reflex control of subcutaneous blood flow in tetraplegic man during postural changes

    DEFF Research Database (Denmark)

    Skagen, K; Jensen, K; Henriksen, O;

    1982-01-01

    1. The effect of head-up tilt upon subcutaneous blood flow in the distal arm and leg was studied in 12 patients with complete traumatic spinal cord transection at the cervical level. 2. Blood flow was measured by the local 133Xe washout technique. 3. Leg lowering induced a 47% decrease in blood f...

  16. Surfactant bolus instillation: effects of different doses on blood pressure and cerebral blood flow velocities

    OpenAIRE

    Rey, M.; Segerer, Hugo; Kiessling, C.; Obladen, Michael

    1994-01-01

    Fifteen preterm infants suffering from respiratory distress syndrome were randomly allocated to receive either high-dose (200 mg/kg) or low-dose (100 mg/kg) surfactant treatment. Retreatments were done with the low dose. Blood pressure, blood gases and cerebral blood flow velocities were determined before and after 24 bolus instillations. With the high dose mean blood pressure and mean cerebral blood flow velocity dropped significantly. With the low dose only mean cerebral blood flow velocity...

  17. Iodoamphetamine as a new tracer for local cerebral blood flow in the rat

    DEFF Research Database (Denmark)

    Rapin, J R; Le Poncin-Lafitte, M; Duterte, D;

    1984-01-01

    blood flow and a more real estimation of hippocampal flow. It is concluded from the brain uptake of the derivatives of both amphetamines during the first minutes following their injection that these tracers can be used as a chemical microembolus for the measurement of local cerebral blood flow....

  18. A Reconstruction Method of Blood Flow Velocity in Left Ventricle Using Color Flow Ultrasound.

    Science.gov (United States)

    Jang, Jaeseong; Ahn, Chi Young; Jeon, Kiwan; Heo, Jung; Lee, DongHak; Joo, Chulmin; Choi, Jung-il; Seo, Jin Keun

    2015-01-01

    Vortex flow imaging is a relatively new medical imaging method for the dynamic visualization of intracardiac blood flow, a potentially useful index of cardiac dysfunction. A reconstruction method is proposed here to quantify the distribution of blood flow velocity fields inside the left ventricle from color flow images compiled from ultrasound measurements. In this paper, a 2D incompressible Navier-Stokes equation with a mass source term is proposed to utilize the measurable color flow ultrasound data in a plane along with the moving boundary condition. The proposed model reflects out-of-plane blood flows on the imaging plane through the mass source term. The boundary conditions to solve the system of equations are derived from the dimensions of the ventricle extracted from 2D echocardiography data. The performance of the proposed method is evaluated numerically using synthetic flow data acquired from simulating left ventricle flows. The numerical simulations show the feasibility and potential usefulness of the proposed method of reconstructing the intracardiac flow fields. Of particular note is the finding that the mass source term in the proposed model improves the reconstruction performance. PMID:26078773

  19. Regulation of cerebral blood flow during exercise.

    Science.gov (United States)

    Querido, Jordan S; Sheel, A William

    2007-01-01

    Constant cerebral blood flow (CBF) is vital to human survival. Originally thought to receive steady blood flow, the brain has shown to experience increases in blood flow during exercise. Although increases have not consistently been documented, the overwhelming evidence supporting an increase may be a result of an increase in brain metabolism. While an increase in metabolism may be the underlying causative factor for the increase in CBF during exercise, there are many modulating variables. Arterial blood gas tensions, most specifically the partial pressure of carbon dioxide, strongly regulate CBF by affecting cerebral vessel diameter through changes in pH, while carbon dioxide reactivity increases from rest to exercise. Muscle mechanoreceptors may contribute to the initial increase in CBF at the onset of exercise, after which exercise-induced hyperventilation tends to decrease flow by pial vessel vasoconstriction. Although elite athletes may benefit from hyperoxia during intense exercise, cerebral tissue is well protected during exercise, and cerebral oxygenation does not appear to pose a limiting factor to exercise performance. The role of arterial blood pressure is important to the increase in CBF during exercise; however, during times of acute hypotension such as during diastole at high-intensity exercise or post-exercise hypotension, cerebral autoregulation may be impaired. The impairment of an increase in cardiac output during exercise with a large muscle mass similarly impairs the increase in CBF velocity, suggesting that cardiac output may play a key role in the CBF response to exercise. Glucose uptake and CBF do not appear to be related; however, there is growing evidence to suggest that lactate is used as a substrate when glucose levels are low. Traditionally thought to have no influence, neural innervation appears to be a protective mechanism to large increases in cardiac output. Changes in middle cerebral arterial velocity are independent of changes in

  20. Flow rate measuring devices for gas flows

    Science.gov (United States)

    Bonfig, K. W.

    1985-07-01

    Flowrate measuring devices are described: volume meter with fixed or mobile walls; turbine meter; throttling procedure; ultrasonic and Doppler methods; vortex method; rotary flowmeter; and swinging body flow measuring procedure. Flowrate can also be measured from the force exerted on bodies immersed in a fluid or based on thermodynamical principles. The characteristics and operating envelope of each device/method are given.

  1. Ambulatory measurement of nocturnal fluctuations in subcutaneous blood flow rate in the lower leg of man during 12-h periods with the portable CdTe(Cl) detector. Methodological considerations

    DEFF Research Database (Denmark)

    Sindrup, J H; Kastrup, J; Jørgensen, B;

    1991-01-01

    Possible sources of error during long-term measurements of subcutaneous blood flow rate with the portable CdTe(Cl) detector system were ruled out in the present study. Local blood flow rates were recorded in the lower legs of normal human subjects by means of the 133Xe wash-out technique. A good...... correlation was found between the portable CdTe(Cl) and stationary NaI(Tl) detector systems both prior to (r = 0.88, P less than 0.0001) and after (r = 0.68, P = 0.07) day over night (12 h) measurements. Identical post-ischaemic reactive hyperaemia could be demonstrated by both detector systems 12 h after...... the application of the isotope depot. This indicates that blood flow rates and vascular reactivity can be measured over 12 h by the portable CdTe(Cl) detector. Identical results were obtained during the 12-h measurements performed with the portable CdTe(Cl) detector attached directly to the skin surface...

  2. Regional cerebral blood flow in diabetic patients

    International Nuclear Information System (INIS)

    N-isopropyl-p-123I-iodoamphetamine (IMP) was used to quantify the regional cerebral blood flow (r-CBF) in 11 diabetic patients (average age; 67.9 years) and 12 non-diabetic subjects (average age; 67.4 years), none of whom had (cerebrovascular disease (CVD) on CT studies. A reference sampling method by continuous arterial blood sampling was used to quantify r-CBF. There were no significant differences in physiological or laboratory data between diabetic and non-diabetic groups except for fasting plasma glucose and HbA1c levels. The average of r-CBF in each region of cerebrum and cerebellum was significantly lower in diabetic group than that in the control group (p<0.01). These observations show that r-CBF of diabetic patients is reduced, even in the absence of findings of CVD on a CT study. (author)

  3. Regional cerebral blood flow in diabetic patients

    Energy Technology Data Exchange (ETDEWEB)

    Nagamachi, Shigeki; Ono, Shinnichi; Nishikawa, Takushi (Nichinan Hospital of Miyazaki Prefecture (Japan)) (and others)

    1993-02-01

    N-isopropyl-p-[sup 123]I-iodoamphetamine (IMP) was used to quantify the regional cerebral blood flow (r-CBF) in 11 diabetic patients (average age; 67.9 years) and 12 non-diabetic subjects (average age; 67.4 years), none of whom had (cerebrovascular disease (CVD) on CT studies). A reference sampling method by continuous arterial blood sampling was used to quantify r-CBF. There were no significant differences in physiological or laboratory data between diabetic and non-diabetic groups except for fasting plasma glucose and HbA[sub 1c] levels. The average of r-CBF in each region of cerebrum and cerebellum was significantly lower in diabetic group than that in the control group (p<0.01). These observations show that r-CBF of diabetic patients is reduced, even in the absence of findings of CVD on a CT study. (author).

  4. Regional cerebral blood flow levels as measured by xenon-CT in vascular territorial low-density areas after subarachnoid hemorrhage are not always ischemic

    Energy Technology Data Exchange (ETDEWEB)

    Fainardi, E. [Arcispedale S. Anna, Neuroradiology Unit, Department of Neurosciences, Ferrara (Italy); Tagliaferri, M.F.; Compagnone, C.; Tanfani, A.; Cocciolo, F.; Targa, L.; Chieregato, A. [Ospedale M. Bufalini, Neurocritical Care Unit, Cesena (Italy); Battaglia, R.; Frattarelli, M. [Ospedale M. Bufalini, Neurosurgery Unit, Cesena (Italy); Pascarella, R. [Ospedale M. Bufalini, Neuroradiology Unit, Cesena (Italy)

    2006-09-15

    The aim of this study was to assess regional cerebral blood flow (rCBV) in areas of CT hypoattenuation appearing in the postoperative period in patients treated for aneurysmal subarachnoid hemorrhage (SAH) using xenon-enhanced CT scanning (Xe-CT). We analyzed 15 patients (5 male and 10 female; mean age 49.7{+-}12.1 years) with SAH on CT performed on admission to hospital and who showed a low-density area within a well-defined vascular territory on CT scans after clipping or coiling of a saccular aneurysm. All zones of hypoattenuation were larger than 1 cm{sup 2} and showed signs of a mass effect suggesting a subacute phase of evolution. Two aneurysms were detected in two patients. Aneurysms were located in the middle cerebral artery (n=7), in the anterior communicating artery (n=6), in the internal carotid artery (n=3), and in the posterior communicating artery (n=1). Treatments were surgical (n=8), endovascular (n=2) or both (n=1). A total of 36 Xe-CT studies were performed and rCBF values were measured in two different regions of interest (ROI): the low-density area, and an area of normal-appearing brain tissue located symmetrically in the contralateral hemisphere. rCBF levels were significantly lower in the low-density area than in the contralateral normal-appearing area (P<0.01). In the low-density areas, irreversible ischemia (CBF <10 ml/100 g per minute) was present in 11/36 lesions (30.6%), ischemic penumbra (CBF 10-20 ml/100 g per minute) and oligemia (CBF 20-34 ml/100 g per minute) in 8/36 lesions (22.2%), relative hyperemia (CBF 34-55 ml/100 g per minute) in 7/36 lesions (19.4%), and absolute hyperemia (CBF >55 ml/100 g per minute) in 2/36 lesions (5.6%). Our study confirmed that rCBF is reduced in new low-density lesions related to specific vascular territories. However, only about one-third of the lesions showed rCBF levels consistent with irreversible ischemia and in a relatively high proportion of lesions, rCBF levels indicated penumbral, oligemic and

  5. Capillary pericytes regulate cerebral blood flow in health and disease

    DEFF Research Database (Denmark)

    Hall, Catherine N; Reynell, Clare; Gesslein, Bodil;

    2014-01-01

    Increases in brain blood flow, evoked by neuronal activity, power neural computation and form the basis of BOLD (blood-oxygen-level-dependent) functional imaging. Whether blood flow is controlled solely by arteriole smooth muscle, or also by capillary pericytes, is controversial. We demonstrate...... blood flow, capillaries dilate before arterioles and are estimated to produce 84% of the blood flow increase. In pathology, ischaemia evokes capillary constriction by pericytes. We show that this is followed by pericyte death in rigor, which may irreversibly constrict capillaries and damage the blood-brain...

  6. Ultrasonic Doppler blood flow meter for extracorporeal circulation

    Science.gov (United States)

    Dantas, Ricardo G.; Costa, Eduardo T.; Maia, Joaquim M.; Nantes Button, Vera L. d. S.

    2000-04-01

    In cardiac surgeries it is frequently necessary to carry out interventions in internal heart structures, and where the blood circulation and oxygenation are made by artificial ways, out of the patient's body, in a procedure known as extracorporeal circulation (EC). During this procedure, one of the most important parameters, and that demands constant monitoring, is the blood flow. In this work, an ultrasonic pulsed Doppler blood flowmeter, to be used in an extracorporeal circulation system, was developed. It was used a 2 MHz ultrasonic transducer, measuring flows from 0 to 5 liters/min, coupled externally to the EC arterial line destined to adults perfusion (diameter of 9.53 mm). The experimental results using the developed flowmeter indicated a maximum deviation of 3.5% of full scale, while the blood flow estimator based in the rotation speed of the peristaltic pump presented deviations greater than 20% of full scale. This ultrasonic flowmeter supplies the results in a continuous and trustworthy way, and it does not present the limitations found in those flowmeters based in other transduction methods. Moreover, due to the fact of not being in contact with the blood, it is not disposable and it does not need sterilization, reducing operational costs and facilitating its use.

  7. Quantitative blood flow velocity imaging using laser speckle flowmetry

    Science.gov (United States)

    Nadort, Annemarie; Kalkman, Koen; van Leeuwen, Ton G.; Faber, Dirk J.

    2016-04-01

    Laser speckle flowmetry suffers from a debated quantification of the inverse relation between decorrelation time (τc) and blood flow velocity (V), i.e. 1/τc = αV. Using a modified microcirculation imager (integrated sidestream dark field - laser speckle contrast imaging [SDF-LSCI]), we experimentally investigate on the influence of the optical properties of scatterers on α in vitro and in vivo. We found a good agreement to theoretical predictions within certain limits for scatterer size and multiple scattering. We present a practical model-based scaling factor to correct for multiple scattering in microcirculatory vessels. Our results show that SDF-LSCI offers a quantitative measure of flow velocity in addition to vessel morphology, enabling the quantification of the clinically relevant blood flow, velocity and tissue perfusion.

  8. Ascending aortic blood flow dynamics following intense exercise.

    Science.gov (United States)

    Kilgour, R D; Sellers, W R

    1990-10-01

    The purpose of this study was to compare and contrast aortic blood flow kinetics during recovery from intense aerobic (maximal oxygen uptake test) and anaerobic (Wingate anaerobic power test) exercise. Fifteen healthy male subjects (VO2max = 56.1 +/- 5.8 mk/kg/min) participated in this study. Beat-to-beat peak aortic blood flow velocity (pkV) and acceleration (pkA) measurements were obtained by placing a 3.0 MHz continuous-wave ultrasonic transducer on the suprasternal notch at rest and during recovery (immediately post-exercise, 2.5 min, and 5.0 min) following the two exercise conditions. Peak velocity and acceleration significantly increased (p less than 0.01) from rest to immediately post-exercise and remained elevated throughout the 5-min recovery period. No differences were observed between the aerobic and anaerobic tests. Stroke distance significantly declined (p less than 0.01) immediately following exercise and progressively rose during the 5-min recovery period. The results indicate that: 1) aortic blood flow kinetics remained elevated during short-term recovery, and 2) intense aerobic and anaerobic exercise exhibit similar post-exercise aortic blood flow kinetics. PMID:2262232

  9. Assessment of maternal cerebral blood flow in patients with preeclampsia

    Directory of Open Access Journals (Sweden)

    Mandić Vesna

    2005-01-01

    Full Text Available Introduction Systemic vasoconstrktion in preeclamptic patients increases vascular resistance, and is manifested by increased arterial blood flow velocity. The aim of the study is to evaluate if there is a change of Doppler indices in maternal medial cerbral artery (MCA in severe preeclampsia due to: 1 severity of clinical symptoms, 2 the beginning of eclamptic attack and 3 the application of anticonvidsive therapy. Material and methods A prospective clinical study included 92 pregnant women, gestational age 28-36 weeks. They were divided into three groups: normotensive (n=30, mild preeclampsia (n=33, and severe preeclampsia (n=29. We investigated maternal cerebral circulation by assessing the MCA. We registrated: pulsatility index (Pi, resistance index (Ri, Systolic/diastolic ratio (S/D, and the maximum systolic, end diastolic and medium velocity. Patients with severe preeclampsia were divided into two subgroups: subgroup 1 included patients without symptoms of threatening eclampsia (n=18; 62.06%; while subgroup 2 included those with symptoms of preeclampsia (n=11; 37.94%. All patients with severe preeclampsia were treated with magnesium sulfate (MgSO4, and cerebral blood flow was measured before and after the treatment. Statistical analysis was done by oneway ANOVA, Student t-test and t-paired sample test. The difference was considered to be significant if p < 0.05. Results Significantly increased Pi, Ri and all velocities were established in the group of patients with severe preeclampsia compared with the other two groups. In the group with severe preeclamsia we registrated significantly increased values of all velocities (patients with signs of threatening eclampsia. After MgSO4 treatment in patients with severe preeclampsia significantly decreased values of Pi, Ri, S/D ratio and all velocities were registered. Discussion In the studied group of patients with severe preclampsia we found increased velocity values, Pi and Ri, especially in

  10. Intelligent Multiphase Flow Measurement

    OpenAIRE

    Ibrahim, Abba A.

    2009-01-01

    The oil and gas industry’s goal of developing high performing multiphase flow metering systems capable of reducing costs in the exploitation of marginal oil and gas reserves, especially in remote environments, cannot be over emphasised. Development of a cost-effective multiphase flow meter to determine the individual phase flow rates of oil, water and gas was experimentally investigated by means of low cost, simple and non-intrusive commercially available sensors. Features from...

  11. Femoral Blood Flow and Cardiac Output During Blood Flow Restricted Leg Press Exercise

    Science.gov (United States)

    Everett, M. E.; Hackney, K.; Ploutz-Snyder, L.

    2011-01-01

    Low load blood flow restricted resistance exercise (LBFR) causes muscle hypertrophy that may be stimulated by the local ischemic environment created by the cuff pressure. However, local blood flow (BF) during such exercise is not well understood. PURPOSE: To characterize femoral artery BF and cardiac output (CO) during leg press exercise (LP) performed at a high load (HL) and low load (LL) with different levels of cuff pressure. METHODS: Eleven subjects (men/women 4/7, age 31.4+/-12.8 y, weight 68.9+/-13.2 kg, mean+/-SD) performed 3 sets of supine left LP to fatigue with 90 s of rest in 4 conditions: HL (%1-RM/cuff pressure: 80%/0); LL (20%/0); LBFR(sub DBP) (20%/1.3 x diastolic blood pressure, BP); LBFR(sub SBP) (20%/1.3 x supine systolic BP). The cuff remained inflated throughout the LBFR exercise sessions. Artery diameter, velocity time integral (VTI), and stroke volume (SV) were measured using Doppler ultrasound at rest and immediately after each set of exercise. Heart rate (HR) was monitored using a 3-lead ECG. BF was calculated as VTI x vessel cross-sectional area. CO was calculated as HR x SV. The data obtained after each set of exercise were averaged and used for analyses. Multi-level modeling was used to determine the effect of exercise condition on dependent variables. Statistical significance was set a priori at p LL (9.92+/-0.82 cm3) > LBFR(sub dBP)(6.47+/-0.79 cm3) > LBFR(sub SBP) (3.51+/-0.59 cm3). Blunted exercise induced increases occurred in HR, SV, and CO after LBFR compared to HL and LL. HR increased 45% after HL and LL and 28% after LBFR (p<0.05), but SV increased (p<0.05) only after HL. Consequently, the increase (p<0.05) in CO was greater in HL and LL (approximately 3 L/min) than in LBFR (approximately 1 L/min). CONCLUSION: BF during LBFR(sub SBP) was 1/3 of that observed in LL, which supports the hypothesis that local ischemia stimulates the LBFR hypertrophic response. As the cuff did not compress the artery, the ischemia may have occurred

  12. Skeletal blood flow, iliac histomorphometry, and strontium kinetics in osteoporosis: a relationship between blood flow and corrected apposition rate

    Energy Technology Data Exchange (ETDEWEB)

    Reeve, J.; Arlot, M.; Wootton, R.; Edouard, C.; Tellez, M.; Hesp, R.; Green, J.R.; Meunier, P.J.

    1988-06-01

    In 20 untreated patients with idiopathic or postmenopausal osteoporosis, kinetic studies of skeletal blood flow (using /sup 18/F) and bone turnover (using /sup 85/Sr) were combined with dynamic histomorphometry performed on transiliac biopsies taken within 6 weeks of each other. In 8 patients the combined studies were repeated after treatment. A further 5 patients were studied only while receiving treatment. As expected, skeletal blood flow measured by /sup 18/F correlated with an index of /sup 85/Sr uptake into the exchangeable pools of bone. Additionally and independently, skeletal blood flow correlated with an index of the work rate of the osteoblasts in each multicellular unit of bone (the corrected apposition rate of Parfitt). These correlations were statistically significant in both the untreated patients (P less than 0.05) and the whole group (P less than 0.001). Further indices related to bone turnover at the level of the skeleton as a whole were significantly associated with skeletal blood flow only in the combined group.

  13. Estimation of cerebral blood flow during cardiopulmonary resuscitation in humans

    DEFF Research Database (Denmark)

    Christensen, S F; Stadeager, Carsten Preben; Siemkowicz, E

    1990-01-01

    Cerebral blood flow (CBF) and cardiac output (CO) were measured during cardiopulmonary resuscitation in patients who were unsuccessfully resuscitated by use of C14-iodoantipyrine injected into the left ventricle. CO varied between 1.3 and 2.2 l/min with mean 1.8 +/- 0.6 l/min (+/- SD) (28 ml...... resuscitation showed signs of maldistribution suggestive of a patchy and incomplete perfusion....

  14. Determination of cerebral blood flow with the EMI CT scanner

    International Nuclear Information System (INIS)

    Cerebral blood flow (CBF) determinations were made in seven baboons and two patients with the EMI CT dedicated head scanner. The method for determining the CBF was tested and measurements were made during physiological states elicited by changes in pCO2 and depth of anaesthesia. The method has a number of advantages, particularly for assessing CBF responses to pCO2 changes. (author)

  15. Renal blood flow distribution during E. coli endotoxin shock in dog.

    Science.gov (United States)

    Kirkebø, A; Tyssebotn, I

    1980-04-01

    The effect of endotoxin on renal blood flow distribution was studied in anesthetized dogs. Renal blood flow was measured as hydrogen clearance by platinum electrodes placed in outer and in inner halves of cortex and by electromagnetic flowmeter. Intravenous injection of E. coli endotoxin, 3-5 mg/kg b. wt., promptly reduced arterial blood pressure (AP) and renal blood flow. After a transient increase for 45 min AP and renal blood flow declined to about 50% of the control 2 1/2-3 h after injection. The reduction in outer cortical blood flow (OCF) was not significantly different from the reduction in inner cortical blood flow (ICF). The hematocrit (Hct) increased from 40.1 +/- 3.8% to 54.6 +/- 8%, but mean renal vascular resistance did not change. Total plasma protein concentration was not significantly elevated. A marked local flow variability was observed in some periods during the phase of shock with declining AP and total renal blood flow at high Hct. Thus renal blood flow showed phasic changes, but the OCF/ICF ratio was not changed during endotoxin shock. Local blood flow instability was observed periodically at high Hct. PMID:6998257

  16. Accuracy of the blood pressure measurement.

    Science.gov (United States)

    Rabbia, F; Del Colle, S; Testa, E; Naso, D; Veglio, F

    2006-08-01

    Blood pressure measurement is the cornerstone for the diagnosis, the treatment and the research on arterial hypertension, and all of the decisions about one of these single aspects may be dramatically influenced by the accuracy of the measurement. Over the past 20 years or so, the accuracy of the conventional Riva-Rocci/Korotkoff technique of blood pressure measurement has been questioned and efforts have been made to improve the technique with automated devices. In the same period, recognition of the phenomenon of white coat hypertension, whereby some individuals with an apparent increase in blood pressure have normal, or reduced, blood pressures when measurement is repeated away from the medical environment, has focused attention on methods of measurement that provide profiles of blood pressure behavior rather than relying on isolated measurements under circumstances that may in themselves influence the level of blood pressure recorded. These methodologies have included repeated measurements of blood pressure using the traditional technique, self-measurement of blood pressure in the home or work place, and ambulatory blood pressure measurement using innovative automated devices. The purpose of this review to serve as a source of practical information about the commonly used methods for blood pressure measurement: the traditional Riva-Rocci method and the automated methods. PMID:17016412

  17. Skeletal blood flow in Paget's disease of bone and its response to calcitonin therapy.

    Science.gov (United States)

    Wootton, R; Reeve, J; Spellacy, E; Tellez-Yudilevich, M

    1978-01-01

    1. Blood flow to the skeleton was measured by the 18F clearance method of Wooton, Reeve & Veall (1976) in 24 patients with untreated Paget's disease. In every patient but one, resting skeletal blood flow was increased. There was a significant positive correlation between skeletal blood flow and serum alkaline phosphatase and between skeletal blood flow and urinary total hydroxyproline excretion. 2. Fourteen patients were re-studied after they had received short-term (7 days or less) or long-term (7 weeks or more) calcitonin. Skeletal blood flow, alkaline phosphatase and urinary hydroxy-proline excretion fell towards normal in every case. There was some evidence from the short-term studies that calcitonin produced a more rapid fall in skeletal blood flow than in alkaline phosphatase. 3. Glomerular filtration rate appeared to increase transiently in response to calcitonin.

  18. Blood flow and oxygenation in peritendinous tissue and calf muscle during dynamic exercise in humans

    DEFF Research Database (Denmark)

    Boushel, R; Langberg, Henning; Green, Stefan Mathias;

    2000-01-01

    1. Circulation around tendons may act as a shunt for muscle during exercise. The perfusion and oxygenation of Achilles' peritendinous tissue was measured in parallel with that of calf muscle during exercise to determine (1) whether blood flow is restricted in peritendinous tissue during exercise......, and (2) whether blood flow is coupled to oxidative metabolism. 2. Seven individuals performed dynamic plantar flexion from 1 to 9 W. Radial artery and popliteal venous blood were sampled for O2, peritendinous blood flow was determined by 133Xe-washout, calf blood flow by plethysmography, cardiac output...... by dye dilution, arterial pressure by an arterial catheter-transducer, and muscle and peritendinous O2 saturation by spatially resolved spectroscopy (SRS). 3. Calf blood flow rose 20-fold with exercise, reaching 44 +/- 7 ml (100 g)-1 min-1 (mean +/- s.e.m. ) at 9 W, while Achilles' peritendinous flow...

  19. Decreased cerebral blood flow after administration of sodium bicarbonate in the distressed newborn infant

    DEFF Research Database (Denmark)

    Lou, H C; Lassen, N A; Fris-Hansen, B

    1978-01-01

    In the course of our studies on cerebral blood flow in newborn infants, we have observed a striking depressing effect of sodium bicarbonate infusion on cerebral blood flow which in some cases may severely aggravate cerebral ischemia. We measured cerebral blood flow before and after the treatment...... with 1 to 8 meqs of sodium bicarbonate in seven distressed newborn infants. The 133 Xe clearance technique was used. The results showed in six of the seven cases a decrease in cerebral blood flow, which in most cases was reduced to 14 to 22 ml/100 g/min, which is about half the value prior to the...

  20. Effect of TIPS placement on portal and splanchnic arterial blood flow in 4-dimensional flow MRI

    Energy Technology Data Exchange (ETDEWEB)

    Stankovic, Zoran [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); University Medical Center Freiburg, Department of Diagnostic Radiology and Medical Physics, Freiburg (Germany); Roessle, Martin; Schultheiss, Michael [University Medical Center Freiburg, Department of Gastroenterology, Freiburg (Germany); Euringer, Wulf; Langer, Mathias [University Medical Center Freiburg, Department of Diagnostic Radiology and Medical Physics, Freiburg (Germany); Salem, Riad; Barker, Alex; Carr, James; Collins, Jeremy D. [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); Markl, Michael [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); Northwestern University, Department of Biomedical Engineering, McCormick School of Engineering, Chicago, IL (United States)

    2015-09-15

    To assess changes in portal and splanchnic arterial haemodynamics in patients undergoing transjugular intrahepatic portosystemic shunt (TIPS) using four-dimensional (4D) flow MRI, a non-invasive, non-contrast imaging technique. Eleven patients undergoing TIPS implantation were enrolled. K-t GRAPPA accelerated non-contrast 4D flow MRI of the liver vasculature was applied with acceleration factor R = 5 at 3Tesla. Flow analysis included three-dimensional (3D) blood flow visualization using time-resolved 3D particle traces and semi-quantitative flow pattern grading. Quantitative evaluation entailed peak velocities and net flows throughout the arterial and portal venous (PV) systems. MRI measurements were taken within 24 h before and 4 weeks after TIPS placement. Three-dimensional flow visualization with 4D flow MRI revealed good image quality with minor limitations in PV flow. Quantitative analysis revealed a significant increase in PV flow (562 ± 373 ml/min before vs. 1831 ± 965 ml/min after TIPS), in the hepatic artery (176 ± 132 ml/min vs. 354 ± 140 ml/min) and combined flow in splenic and superior mesenteric arteries (770 ml/min vs. 1064 ml/min). Shunt-flow assessment demonstrated stenoses in two patients confirmed and treated at TIPS revision. Four-dimensional flow MRI might have the potential to give new information about the effect of TIPS placement on hepatic perfusion. It may explain some unexpected findings in clinical observation studies. (orig.)

  1. Effect of TIPS placement on portal and splanchnic arterial blood flow in 4-dimensional flow MRI

    International Nuclear Information System (INIS)

    To assess changes in portal and splanchnic arterial haemodynamics in patients undergoing transjugular intrahepatic portosystemic shunt (TIPS) using four-dimensional (4D) flow MRI, a non-invasive, non-contrast imaging technique. Eleven patients undergoing TIPS implantation were enrolled. K-t GRAPPA accelerated non-contrast 4D flow MRI of the liver vasculature was applied with acceleration factor R = 5 at 3Tesla. Flow analysis included three-dimensional (3D) blood flow visualization using time-resolved 3D particle traces and semi-quantitative flow pattern grading. Quantitative evaluation entailed peak velocities and net flows throughout the arterial and portal venous (PV) systems. MRI measurements were taken within 24 h before and 4 weeks after TIPS placement. Three-dimensional flow visualization with 4D flow MRI revealed good image quality with minor limitations in PV flow. Quantitative analysis revealed a significant increase in PV flow (562 ± 373 ml/min before vs. 1831 ± 965 ml/min after TIPS), in the hepatic artery (176 ± 132 ml/min vs. 354 ± 140 ml/min) and combined flow in splenic and superior mesenteric arteries (770 ml/min vs. 1064 ml/min). Shunt-flow assessment demonstrated stenoses in two patients confirmed and treated at TIPS revision. Four-dimensional flow MRI might have the potential to give new information about the effect of TIPS placement on hepatic perfusion. It may explain some unexpected findings in clinical observation studies. (orig.)

  2. Anisodamine augments mucosal blood flow during gut ischemia/reperfusion

    Institute of Scientific and Technical Information of China (English)

    Hu Sen; Sheng Zhiyong

    2002-01-01

    Objective: To determine if anisodamine is able to augment mucosal perfusion during gut ischemia-reperfusion (I/R). Methods: A jejunal sac was formed in Sprague Dawley rat. A Laser Doppler probe and a tonometer were inserted into the sac which was filled with saline. The superior mesenteric artery was occluded (SMAO) for 60minutes followed by 90 minutes of reperfusion. At the end of 60 minutes of SMAO, either 0.2mg/kg of anisodmine or dobutamine was injected into the jejunal sac. Laser Doppler mucosal blood flow and regional PCO2 (PrCO2) measurements were made. Results: Mucosal blood flow was significantly increased at 30,60 and 90 minutes of reperfusion (R30, R60, R90 ) when intraluminal anisodamine or dobutamine was introduced compared to intraluminal saline only (44±3.3)% or (48±4.1)% vs. (37±2.6) % at R30, (57±5.0)% or (56±4.7)% vs. (45±2.7)% at R60, (64±3.3) % or (56 ± 4.2) % vs. (48 ± 3.4) % at R90 , respectively P<0.05). Blood flow changes were also reflected by lowering of jejunal PrCO2 measurements after intraluminal anisodamine or dobutamine compared with that of the saline controls (41±3. 1)mmHg or (44±3.0)mmHg vs. (49±3.7) mmHg at R30 , (38±3.7)mmHg or (40±2. 1)mmHg vs. (47±3.8) mmHgat R60, (34±2.1) mmHg or (39± 3.0) mmHg vs. (46±3.4) mmHg at R90, respectively,P<0. 05). The most interesting finding was that there were significantly higher mucosal blood flow and lower jejunal PrCO2 in anisodamine group than those in dobutamine group at 90 minutes of reperfusion (64± 3.3) %vs. (56±4.2)% for blood flow or (34 ± 2.1)mmHg vs. (39 ± 3.0)mmHg for PrCO2, respectively, P<0.05),suggesting that anisodamine had more lasting effect on mucosal perfusion than dobutamine. Conclusions:Intraluminal anisodamine can augment mucosal blood flow during gut I/R, and it may provide the protective effect on gut from ischemia and reperfusion injury.

  3. Cerebral blood flow and metabolism during sleep

    DEFF Research Database (Denmark)

    Madsen, Peter Lund; Vorstrup, S

    1991-01-01

    A review of the current literature regarding sleep-induced changes in cerebral blood flow (CBF) and cerebral metabolic rate (CMR) is presented. Early investigations have led to the notion that dreamless sleep was characterized by global values of CBF and CMR practically at the level of wakefulness......, while rapid eye movement (REM) sleep (dream sleep) was a state characterized by a dramatically increased level of CBF and possibly also of CMR. However, recent investigations firmly contradict this notion. Investigations on CBF and CMR performed during non-REM sleep, taking the effect of different...... levels of sleep into consideration, show that light sleep (stage II) is characterized by global levels of CBF and CMR only slightly reduced by 3-10% below the level associated with wakefulness, whereas CBF and CMR during deep sleep (stage III-IV) is dramatically reduced by 25-44%. Furthermore, recent...

  4. Mapping blood flow directionality in the human brain.

    Science.gov (United States)

    Park, Sung-Hong; Do, Won-Joon; Choi, Seung Hong; Zhao, Tiejun; Bae, Kyongtae Ty

    2016-07-01

    Diffusion properties of tissue are often expressed on the basis of directional variance, i.e., diffusion tensor imaging. In comparison, common perfusion-weighted imaging such as arterial spin labeling yields perfusion in a scalar quantity. The purpose of this study was to test the feasibility of mapping cerebral blood flow directionality using alternate ascending/descending directional navigation (ALADDIN), a recently-developed arterial spin labeling technique with sensitivity to blood flow directions. ALADDIN was applied along 3 orthogonal directions to assess directional blood flow in a vector form and also along 6 equally-spaced directions to extract blood flow tensor matrix (P) based on a blood flow ellipsoid model. Tensor elements (eigenvalues, eigenvectors, etc) were calculated to investigate characteristics of the blood flow tensor, in comparison with time-of-flight MR angiogram. While the directions of the main eigenvectors were heterogeneous throughout the brain, regional clusters of blood flow directionality were reproducible across subjects. The technique could show heterogeneous blood flow directionality within and around brain tumor, which was different from that of the contralateral normal side. The proposed method is deemed to provide information of blood flow directionality, which has not been demonstrated before. The results warrant further studies to assess changes in the directionality map as a function of scan parameters, to understand the signal sources, to investigate the possibility of mapping local blood perfusion directionality, and to evaluate its usefulness for clinical diagnosis.

  5. Photoacoustic Doppler flow measurement in optically scattering media

    OpenAIRE

    Fang, Hui; Maslov, Konstantin; Wang, Lihong V.

    2007-01-01

    We recently observed the photoacoustic Doppler effect from flowing small light-absorbing particles. Here, we apply the effect to measure blood-mimicking fluid flow in an optically scattering medium. The light scattering in the medium decreases the amplitude of the photoacoustic Doppler signal but does not affect either the magnitude or the directional discrimination of the photoacoustic Doppler shift. This technology may hold promise for a new Doppler method for measuring blood flow in microc...

  6. Functional effects of neuropeptide Y receptors on blood flow and nitric oxide levels in the human nose

    DEFF Research Database (Denmark)

    Cervin, A; Onnerfält, J; Edvinsson, L;

    1999-01-01

    The aim of this study was to examine dose-dependent effects of intranasal application of neuropeptide Y (NPY) on nasal mucosal blood flow, blood content, and intranasal nitric oxide (NO) concentration. Blood flow was measured by laser Doppler flowmetry (LDF) and blood content by rhinomanometry...... flow, as well as the blood content. The effect is probably mediated via Y1 receptors. NPY receptor agonists may prove beneficial in the treatment of the congested nose in allergic or vasomotor rhinitis....

  7. Subcutaneous blood flow in early male pattern baldness

    International Nuclear Information System (INIS)

    The subcutaneous blood flow (SBF) was measured by the 133Xe washout method in the scalp of 14 patients with early male pattern baldness. Control experiments were performed in 14 normal haired men matched for age. The SBF in the scalp of the normal individuals was about 10 times higher than previously reported SBF values in other anatomical regions. In patients with early male pattern baldness, SBF was 2.6 times lower than the values found in the normal individuals (13.7 +/- 9.6 vs 35.7 +/- 10.5 ml/100 g/min-1). This difference was statistically significant (p much less than 0.001). A reduced nutritive blood flow to the hair follicles might be a significant event in the pathogenesis of early male pattern baldness

  8. Subcutaneous blood flow in early male pattern baldness

    Energy Technology Data Exchange (ETDEWEB)

    Klemp, P.; Peters, K.; Hansted, B.

    1989-05-01

    The subcutaneous blood flow (SBF) was measured by the /sup 133/Xe washout method in the scalp of 14 patients with early male pattern baldness. Control experiments were performed in 14 normal haired men matched for age. The SBF in the scalp of the normal individuals was about 10 times higher than previously reported SBF values in other anatomical regions. In patients with early male pattern baldness, SBF was 2.6 times lower than the values found in the normal individuals (13.7 +/- 9.6 vs 35.7 +/- 10.5 ml/100 g/min-1). This difference was statistically significant (p much less than 0.001). A reduced nutritive blood flow to the hair follicles might be a significant event in the pathogenesis of early male pattern baldness.

  9. Cerebral autoregulation control of blood flow in the brain

    CERN Document Server

    Payne, Stephen

    2016-01-01

    This Brief provides a comprehensive introduction to the control of blood flow in the brain. Beginning with the basic physiology of autoregulation, the author goes on to discuss measurement techniques, mathematical models, methods of analysis, and relevant clinical conditions, all within this single volume. The author draws together this disparate field, and lays the groundwork for future research directions. The text gives an up-to-date review of the state of the art in cerebral autoregulation, which is particularly relevant as cerebral autoregulation moves from the laboratory to the bedside. Cerebral Autoregulation will be useful to researchers in the physical sciences such as mathematical biology, medical physics, and biomedical engineering whose work is concerned with the brain. Researchers in the medical sciences and clinicians dealing with the brain and blood flow, as well as industry professionals developing techniques such as ultrasound, MRI, and CT will also find this Brief of interest.

  10. Mucosal/submucosal blood flow in the gut wall determined by local washout of 133Xenon

    DEFF Research Database (Denmark)

    Mortensen, Peter; Olsen, J; Bülow, J;

    1991-01-01

    and the small intestine the 133Xe washout plotted in a semilogarithmic diagram showed a multiexponential configuration. Histological examination and localization studies showed shunting by diffusion of 133Xe in the intestinal mucosa explaining the multiexponential configuration of the washout curve. Therefore......A 133Xe washout technique for measuring the blood flow in the intestinal mucosa is introduced and evaluated. In 11 anaesthetized pigs a laparotomy was performed and the mucosal blood flow rate in the intestine of the pig was determined by a local epimucosal application of 133Xe. In both the colon...... the initial slope of the washout was used for measuring blood flow rate. Blood flow rate was simultaneously measured by microsphere entrapment technique. There was an excellent correlation between the blood flow rate determined by the two techniques the correlation coefficient R being 0.89 in the small...

  11. Generating New Blood Flow : Integrating Developmental Biology and Tissue Engineering

    NARCIS (Netherlands)

    Krenning, Guido; Moonen, Jan-Renier A. J.; van Luyn, Marja J. A.; Harmsen, Martin C.

    2008-01-01

    Vascular tissue engineering aims to restore blood flow by seeding artificial tubular scaffolds with endothelial and smooth muscle cells, thus creating bioartificial blood vessels. Herein, the progenitors of smooth muscle and endothelial cells hold great promise because they efficiently differentiate

  12. Dynamic noise correction for IVUS quantitative volume blood flow: methods and numerical validation.

    NARCIS (Netherlands)

    Lupotti, F.A.; Korte, C.L. de; Mastik, F.; Steen, A.F.W. van der

    2002-01-01

    In recent years, a new method to measure transverse blood flow based on the decorrelation of the radio-frequency (RF) signals, has been developed. Transverse blood flow estimation may be influenced by noise. In this paper, we investigated a new correlation-based method for noise correction. The deco

  13. Should blood flow during cardiopulmonary bypass be individualized more than to body surface area?

    DEFF Research Database (Denmark)

    Thomassen, Sisse Anette; Larsson, A; Andreasen, Jan Jesper;

    Blood flow during cardiopulmonary bypass (CPB) is calculated on body surface area (BSA). Increasing comorbidity, age and weight of today's cardiac patients question this calculation as it may not reflect individual metabolic requirement. The hypothesis was that a measured cardiac index (CI) prior...... not improve cerebral and systemic oxygenation compared to a blood flow based on BSA....

  14. Margination of leukocytes in blood flow through small tubes.

    Science.gov (United States)

    Goldsmith, H L; Spain, S

    1984-03-01

    Leukocyte margination in the vessels of the microcirculation has been attributed to a flow-dependent interaction with red cells. To determine the extent of this effect, experiments with human blood were done in 100- to 180-micron tubes to detect changes in cell distribution as a function of hematocrit and flow rate. Using a flow visualization technique, the leukocyte concentration distribution was determined in 45% ghost cell suspensions. Migration of cells toward the wall was observed at centerline velocities greater than 1 mm sec-1 and increased with increasing flow rate. The effect was probably due to a more rapid inward migration of ghosts than leukocytes because of fluid inertia and cell density differences. Experiments were therefore carried out in whole blood at hematocrits from 20 to 60%, measuring the number concentration of leukocytes and erythrocytes within the tube, nt, and comparing it to that in the infusing reservoir, no, (Fahraeus effect). At mean tube shear rates G less than 100 sec-1, nt/no less than 1 for both leukocytes and erythrocytes showing net migration of cells away from the wall, although at nearly all hematocrits there was an enrichment of leukocytes relative to erythrocytes in the tubes. At G less than 50 sec-1, nt/no remained less than 1 for erythrocytes but increased to greater than 1 for leukocytes showing migration toward the wall, the increase being greatest at 20% hematocrit in the 100-micron tubes. The nature of the effect was revealed by cine films which showed that, as the flow rate decreased, erythrocytes formed rouleaux which migrated inward creating a core and displacing leukocytes to the periphery. In control experiments using washed blood cells in phosphate buffer-albumin, nt/no less than 1 for both leukocytes and erythrocytes at all G and hematocrits, and leukocytes were now distributed. Cine films of washed blood confirmed that, in the absence of rouleaux, no significant inward migration of erythrocytes occurred. PMID

  15. The blood flow changes associated with idiopathic and secondary intracranial hypertension

    International Nuclear Information System (INIS)

    Full text: The radiological diagnosis of idiopathic intracranial hypertension (IIH) is one of exclusion and as the MR venogram is prone to flow artefacts, the diagnosis of secondary intracranial hypertension (SIH) can also be problematic. The purpose of this paper is to define the blood flow characteristics, which are useful in the diagnosis of these conditions. Twelve patients with clinical findings suggestive of IIH and 12 control subjects were investigated with MR venography and MR flow quantification studies of the cerebral arteries and veins. Total cerebral blood flow, superior sagittal sinus (SSS) and straight sinus (ST) blood flows were measured. MR venography confirmed 7 of the 12 patients had venous outflow obstruction and thus SIH. The remaining 5 patients had IIH. The control patients mean total blood flow was 855 ml/min, the SSS flow was 400ml/min and the ST flow 117 ml/min. The total blood flow in the IIH patients was 46% higher (P = 0.0002) and the ST blood flow 38% higher (P = 0.05) than the control group, the SSS flow was 17% higher but this failed to reach significance. In SIH the SSS flow was reduced by 25% (P = 0.003) compared with the control group, the total and ST blood flow were not significantly altered. In IIH there is hyperaemia and the SSS appears limited in its ability to increase flow, therefore venous collaterals carry a greater load. In SIH, selective obstruction of the SSS reduces flow in this vessel but total blood flow is normal indicating there is also increased flow in collateral veins. Presumably the limited ability of the SSS to drain blood away from the brain in each condition raises venous sinus pressure and alters CSF resorption giving raised CSF pressure. Copyright (2002) Blackwell Science Pty Ltd

  16. Skin blood flow changes during local arm heating: comparison between the laser-Doppler and frequency-corrected thermal clearance measurement

    Science.gov (United States)

    Raamat, Rein; Kudimov, Boris

    2003-08-01

    We compared two different techniques for non-invasive registration of fingertip skin blood flow changes in 5 healthy volunteers during local arm heating in the water bath from 21°C to 42°C. The laser-Doppler flowmetry (LDF) probe was attached to the pulp of the index finger, while the thermal clearance (TC) probe was fixed to the pulp of the middle finger. Computer simulation method, provided by the MATLAB package, was introduced to speed up the frequency response of the TC probe. By correlation analysis we evaluated the similarity of LDF and TC recordings. The median correlation coefficient for the relationship LDF versus TC equaled 0.74, the range being from 0.63 to 0.82. After an introduction of the computer-based frequency correction, the correlation increased till 0.88 with the range from 0.82 to 0.91. The corresponding improvement in r2 ("goodness to fit") was 41%.

  17. Invariant Measures for Cherry Flows

    Science.gov (United States)

    Saghin, Radu; Vargas, Edson

    2013-01-01

    We investigate the invariant probability measures for Cherry flows, i.e. flows on the two-torus which have a saddle, a source, and no other fixed points, closed orbits or homoclinic orbits. In the case when the saddle is dissipative or conservative we show that the only invariant probability measures are the Dirac measures at the two fixed points, and the Dirac measure at the saddle is the physical measure. In the other case we prove that there exists also an invariant probability measure supported on the quasi-minimal set, we discuss some situations when this other invariant measure is the physical measure, and conjecture that this is always the case. The main techniques used are the study of the integrability of the return time with respect to the invariant measure of the return map to a closed transversal to the flow, and the study of the close returns near the saddle.

  18. Resistance exercise with different volumes: blood pressure response and forearm blood flow in the hypertensive elderly

    Directory of Open Access Journals (Sweden)

    Brito AF

    2014-12-01

    Full Text Available Aline de Freitas Brito,1 Caio Victor Coutinho de Oliveira,2 Maria do Socorro Brasileiro-Santos,1 Amilton da Cruz Santos1 1Physical Education Department, 2Research Laboratory for Physical Training Applied to Performance and Health, Federal University of Paraíba, João Pessoa, Brazil Background: The purpose of this study was to evaluate the effect of two sessions of resistance exercise with different volumes on post-exercise hypotension, forearm blood flow, and forearm vascular resistance in hypertensive elderly subjects.Methods: The study was conducted with ten hypertensive elderly (65±3 years, 28.7±3 kg/m2 subjected to three experimental sessions, ie, a control session, exercise with a set (S1, and exercise with three sets (S3. For each session, the subjects were evaluated before and after intervention. In the pre-intervention period, blood pressure, forearm blood flow, and forearm vascular resistance were measured after 10 minutes of rest in the supine position. Thereafter, the subjects were taken to the gym to perform their exercise sessions or remained at rest during the same time period. Both S1 and S3 comprised a set of ten repetitions of ten exercises, with an interval of 90 seconds between exercises. Subsequently, the measurements were again performed at 10, 30, 50, 70, and 90 minutes of recovery (post-intervention in the supine position.Results: Post-exercise hypotension was greater in S3 than in S1 (systolic blood pressure, −26.5±4.2 mmHg versus −17.9±4.7 mmHg; diastolic blood pressure, −13.8±4.9 mmHg versus −7.7±5 mmHg, P<0.05. Similarly, forearm blood flow and forearm vascular resistance changed significantly in both sessions with an increase and decrease, respectively, that was more evident in S3 than in S1 (P<0.05.Conclusion: Resistance exercises with higher volume were more effective in causing post-exercise hypotension, being accompanied by an increase in forearm blood flow and a reduction of forearm vascular

  19. Time-resolved volumetric MRI blood flow: a Doppler ultrasound perspective

    Science.gov (United States)

    van Pelt, Roy; Oliván Bescós, Javier; Nagel, Eike; Vilanova, Anna

    2014-03-01

    Hemodynamic information is increasingly inspected to assess cardiovascular disease. Abnormal blood-flow patterns include high-speed jet flow and regurgitant flow. Such pathological blood-flow patterns are nowadays mostly inspected by means of color Doppler ultrasound imaging. To date, Doppler ultrasound has been the prevailing modality for blood-flow analysis, providing non-invasive and cost-effective blood-flow imaging. Since recent years, magnetic resonance imaging (MRI) is increasingly employed to measure time-resolved blood-flow data. Albeit more expensive, MRI enables volumetric velocity encoding, providing true vector-valued data with less noise. Domain experts in the field of ultrasound and MRI have extensive experience in the interpretation of blood-flow information, although they employ different analysis techniques. We devise a visualization framework that extends on common Doppler ultrasound visualizations, exploiting the added value of MRI velocity data, and aiming for synergy between the domain experts. Our framework enables experts to explore the advantages and disadvantages of the current renditions of their imaging data. Furthermore, it facilitates the transition from conventional Doppler ultrasound images to present-day high-dimensional velocity fields. To this end, we present a virtual probe that enables direct exploration of MRI-acquired blood-flow velocity data using user-friendly interactions. Based on the probe, Doppler ultrasound inspired visualizations convey both in-plane and through-plane blood-flow velocities. In a compound view, these two-dimensional visualizations are linked to state-of-the-art three-dimensional blood-flow visualizations. Additionally, we introduce a novel volume rendering of the blood-flow velocity data that emphasizes anomalous blood-flow patterns. The visualization framework was evaluated by domain experts, and we present their feedback.

  20. Cerebral blood flow is reduced in patients with sepsis syndrome

    International Nuclear Information System (INIS)

    The relationship between sepsis-induced CNS dysfunction and changes in brain blood flow remains unknown, and animal studies examining the influence of sepsis on cerebral blood flow (CBF) do not satisfactorily address that relationship. We measured CBF and cerebrovascular reactivity to CO2 in nine patients with sepsis syndrome using the 133Xe clearance technique. Mean CBF was 29.6 +/- 15.8 (SD) ml/100 g.min, significantly lower than the normal age-matched value in this laboratory of 44.9 +/- 6.2 ml/100 g.min (p less than .02). This depression did not correlate with changes in mean arterial pressure. Despite the reduction in CBF, the specific reactivity of the cerebral vasculature to changes in CO2 was normal, 1.3 +/- 0.9 ml/100 g.min/mm Hg. Brain blood flow is reduced in septic humans; the contribution of this reduction to the metabolic and functional changes observed in sepsis requires further study

  1. Cerebral blood flow is reduced in patients with sepsis syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Bowton, D.L.; Bertels, N.H.; Prough, D.S.; Stump, D.A.

    1989-05-01

    The relationship between sepsis-induced CNS dysfunction and changes in brain blood flow remains unknown, and animal studies examining the influence of sepsis on cerebral blood flow (CBF) do not satisfactorily address that relationship. We measured CBF and cerebrovascular reactivity to CO/sub 2/ in nine patients with sepsis syndrome using the /sup 133/Xe clearance technique. Mean CBF was 29.6 +/- 15.8 (SD) ml/100 g.min, significantly lower than the normal age-matched value in this laboratory of 44.9 +/- 6.2 ml/100 g.min (p less than .02). This depression did not correlate with changes in mean arterial pressure. Despite the reduction in CBF, the specific reactivity of the cerebral vasculature to changes in CO/sub 2/ was normal, 1.3 +/- 0.9 ml/100 g.min/mm Hg. Brain blood flow is reduced in septic humans; the contribution of this reduction to the metabolic and functional changes observed in sepsis requires further study.

  2. Predicting Endometrium Receptivity with Parameters of Spiral Artery Blood Flow

    Institute of Scientific and Technical Information of China (English)

    GONG Xuehao; LI Quanshui; ZHANG Qingping; ZHU Guijin

    2005-01-01

    Summary: In order To evaluate whether the parameters of spiral artery blood flow, as measured by transvaginal color Doppler, may be used to assess endometrium receptivity prior to embryo transfer (ET), a retrospective study of 94 infertile women who had undergone ART treatments with different outcomes (pregnant or nonpregnant) was done. Subendometrial blood flow was evaluated. The resistance index (RI), systolic/diastolic ratio (S/D) and pulsatility index (PI) were significantly lower in those who achieved pregnancy as compared with those who did not: 0.62±0.04 vs 0.68±0.04 (P<0.001), 2.66±0.33 vs 3.19±0.39 (P<0.01) and 1.15±0.17 vs 1.34±0.22 (P<0.05), respectively. Furthermore, when RI>0.72, PI>1.6, and S/D>3.6, no pregnancy occurred. These data suggest that the parameters of spiral artery blood flow could be used as a new assay in predicting endometrial receptivity before ET.

  3. In vivo analysis of physiological 3D blood flow of cerebral veins

    Energy Technology Data Exchange (ETDEWEB)

    Schuchardt, Florian; Schroeder, Laure; Baeuerle, Jochen; Harloff, Andreas [University Medical Centre, Department of Neurology, Freiburg (Germany); Anastasopoulos, Constantin [University Medical Center, Department of Neuropaediatrics and Muscle Disorders, Freiburg (Germany); University Medical Centre, Department of Neuroradiology, Freiburg (Germany); Markl, Michael [Northwestern University, Department of Radiology, Feinberg School of Medicine and McCormick School of Engineering, Chicago, IL (United States); Hennemuth, Anja; Drexl, Johann [Fraunhofer MEVIS, Bremen (Germany); Valdueza, Jose M. [Neurological Center, Segeberger Kliniken, Bad Segeberg (Germany); Mader, Irina [University Medical Centre, Department of Neuroradiology, Freiburg (Germany)

    2015-08-15

    To visualize and quantify physiological blood flow of intracranial veins in vivo using time-resolved, 3D phase-contrast MRI (4D flow MRI), and to test measurement accuracy. Fifteen healthy volunteers underwent repeated ECG-triggered 4D flow MRI (3 Tesla, 32-channel head coil). Intracranial venous blood flow was analysed using dedicated software allowing for blood flow visualization and quantification in analysis planes at the superior sagittal, straight, and transverse sinuses. MRI was evaluated for intra- and inter-observer agreement and scan-rescan reproducibility. Measurements of the transverse sinuses were compared with transcranial two-dimensional duplex ultrasound. Visualization of 3D blood flow within cerebral sinuses was feasible in 100 % and within at least one deep cerebral vein in 87 % of the volunteers. Blood flow velocity/volume increased along the superior sagittal sinus and was lower in the left compared to the right transverse sinus. Intra- and inter-observer reliability and reproducibility of blood flow velocity (mean difference 0.01/0.02/0.02 m/s) and volume (mean difference 0.0002/-0.0003/0.00003 l/s) were good to excellent. High/low velocities were more pronounced (8 % overestimation/9 % underestimation) in MRI compared to ultrasound. Four-dimensional flow MRI reliably visualizes and quantifies three-dimensional cerebral venous blood flow in vivo and is promising for studies in patients with sinus thrombosis and related diseases. (orig.)

  4. Numerical simulation of noninvasive blood pressure measurement.

    Science.gov (United States)

    Hayashi, Satoru; Hayase, Toshiyuki; Shirai, Atsushi; Maruyama, Masaru

    2006-10-01

    In this paper, a simulation model based on the partially pressurized collapsible tube model for reproducing noninvasive blood pressure measurement is presented. The model consists of a collapsible tube, which models the pressurized part of the artery, rigid pipes connected to the collapsible tube, which model proximal and distal region far from the pressurized part, and the Windkessel model, which represents the capacitance and the resistance of the distal part of the circulation. The blood flow is simplified to a one-dimensional system. Collapse and expansion of the tube is represented by the change in the cross-sectional area of the tube considering the force balance acting on the tube membrane in the direction normal to the tube axis. They are solved using the Runge-Kutta method. This simple model can easily reproduce the oscillation of inner fluid and corresponding tube collapse typical for the Korotkoff sounds generated by the cuff pressure. The numerical result is compared with the experiment and shows good agreement. PMID:16995754

  5. Renal blood flow and metabolism after cold ischaemia

    DEFF Research Database (Denmark)

    Henriksen, J H; Petersen, H K

    1984-01-01

    Peroperative measurements of renal blood flow (RBF), renal O2-uptake, and renal venous lactate/pyruvate (L/P) ratio were performed before and after a period of 30-71 min of hypothermic (10-15 degrees C) renal ischaemia in nine patients, undergoing surgery for renal calculi. Before ischaemia, RBF.......01) immediately after re-established perfusion and 36% (P less than 0.02) 30 min later. In one additional patient, who had a short warm ischaemia (8 min), the flow pattern was the same. As arterial pressure remained constant, the reduced RBF signifies an increased renal vascular resistance. Renal O2-uptake...... and renal venous L/P ratio were almost constant, indicating no significant anaerobic processes being involved in the flow response. None of the patients showed any signs of reactive hyperaemia. It is concluded that hypothermic renal ischaemia may be followed by an increased renal vascular resistance even...

  6. Invariant measures for Cherry flows

    CERN Document Server

    Saghin, Radu

    2011-01-01

    We investigate the invariant probability measures for Cherry flows, i.e. flows on the two-torus which have a saddle, a source, and no other fixed points, closed orbits or homoclinic orbits. In the case when the saddle is dissipative or conservative we show that the only invariant probability measures are the Dirac measures at the two fixed points, and the Dirac measure at the saddle is the physical measure. In the other case we discuss some situations when there exists another invariant measure supported on the quasi-minimal set, which is the physical measure, and conjecture that this is always the case. The main techniques used are the study of the integrability of the return time with respect to the invariant measure of the return map to a closed transversal to the flow, and the study of the close returns near the saddle.

  7. Coupling of porcine bone blood flow and metabolism in high-turnover bone disease measured by [{sup 15}O]H{sub 2}O and [{sup 18}F]fluoride ion positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Piert, Morand [Nuclear Medicine, Klinikum Rechts der Isar, Technical University of Munich (Germany); Machulla, Hans-Juergen; Stahlschmidt, Anke; Becker, Georg A. [Radiopharmacy Section, PET Center, University of Tuebingen (Germany); Jahn, Michael; Zittel, Tilman T. [Department of Abdominal and Transplantation Surgery, University of Tuebingen (Germany)

    2002-07-01

    Previously, we identified a parathyroid hormone-related high-turnover bone disease after gastrectomy in mini pigs. Dynamic [{sup 18}F]fluoride ion positron emission tomography (PET) revealed that bone metabolism was significantly increased, but that bone blood flow derived from permeability-surface area product (PS product)-corrected K{sub 1} values was not. Since bone blood flow and metabolism are coupled in normal bone tissues, we hypothesised that the capillary permeability and/or surface area might be altered in high-turnover bone disease. The ''true'' bone blood flow (f{sub H2O}) was measured in vertebral bodies by dynamic [{sup 15}O]H{sub 2}O PET, followed by a 120-min dynamic [{sup 18}F]fluoride ion PET study, 6 months after total gastrectomy (n=5) and compared with results in sham-operated animals (n=5). Estimates for bone blood flow based on PS-corrected K{sub 1} values (f) and the net uptake of fluoride in bone tissue (K{sub i}), representing the bone metabolic activity, were calculated using standard compartmental modelling and non-linear fitting. Gastrectomy was followed by a significant elevation of K{sub i} and k{sub 3} (P<0.05), which was mainly caused by an increase of the fraction of bound tracer in tissue (P<0.01). In contrast, f{sub H2O}, f, the single-pass extraction fraction of [{sup 18}F]fluoride (E) and the volume of distribution (DV) of [{sup 18}F]fluoride were not significantly different between groups. In both groups, a coupling of the mean f{sub H2O} and K{sub i} values was found, but the intercept with the y-axis was higher in high-turnover bone disease. It is concluded that in high-turnover bone disease following gastrectomy, the PS product for [{sup 18}F]fluoride remains unchanged. Therefore, even in high-turnover bone diseases, [{sup 18}F]fluoride ion PET can provide reliable blood flow estimates (f), as long as a proper PS product correction is applied. The increased bone metabolism in high-turnover bone disease

  8. Coupling of porcine bone blood flow and metabolism in high-turnover bone disease measured by [15O]H2O and [18F]fluoride ion positron emission tomography

    International Nuclear Information System (INIS)

    Previously, we identified a parathyroid hormone-related high-turnover bone disease after gastrectomy in mini pigs. Dynamic [18F]fluoride ion positron emission tomography (PET) revealed that bone metabolism was significantly increased, but that bone blood flow derived from permeability-surface area product (PS product)-corrected K1 values was not. Since bone blood flow and metabolism are coupled in normal bone tissues, we hypothesised that the capillary permeability and/or surface area might be altered in high-turnover bone disease. The ''true'' bone blood flow (fH2O) was measured in vertebral bodies by dynamic [15O]H2O PET, followed by a 120-min dynamic [18F]fluoride ion PET study, 6 months after total gastrectomy (n=5) and compared with results in sham-operated animals (n=5). Estimates for bone blood flow based on PS-corrected K1 values (f) and the net uptake of fluoride in bone tissue (Ki), representing the bone metabolic activity, were calculated using standard compartmental modelling and non-linear fitting. Gastrectomy was followed by a significant elevation of Ki and k3 (PH2O, f, the single-pass extraction fraction of [18F]fluoride (E) and the volume of distribution (DV) of [18F]fluoride were not significantly different between groups. In both groups, a coupling of the mean fH2O and Ki values was found, but the intercept with the y-axis was higher in high-turnover bone disease. It is concluded that in high-turnover bone disease following gastrectomy, the PS product for [18F]fluoride remains unchanged. Therefore, even in high-turnover bone diseases, [18F]fluoride ion PET can provide reliable blood flow estimates (f), as long as a proper PS product correction is applied. The increased bone metabolism in high-turnover bone disease after gastrectomy is mainly related to an up-regulation of the amount of ionic exchange of [18F]fluoride with the bone matrix, while tracer delivery remains unchanged. (orig.)

  9. Matas test combined with MR flow measurement

    International Nuclear Information System (INIS)

    Prior to the temporary or permanent therapeutic occlusion of the carotid artery, evaluation of the cerebral collateral circulation via the circle of Willis is necessary in order to prevent complications. The purpose of our study was to evaluate the flow velocity of the contralateral common carotid artery using Renal Time Acquisition and Velocity Evaluation (RACE) before and during a Matas test and to estimate brain collateral circulation. Five normal subjects were studied with a 1.5 T superconducting imager (Siemens, Erlangen) using a neck coil. RACE is a one-dimensional projective flow measurement technique using fast low angle shot (FLASH) without phase encoding gradient (FLASH sequence: TR=20 ms, TE=6 ms, FA=90 degrees, FOV=220 mm, slice thickness=8 mm). The total acquisition time is about 10 seconds without need for electrocardiographic synchronization. Flow velocity of the common carotid artery was evaluated using the RACE technique before and during a Matas test. The relative flow ratio of the contralateral carotid artery (flow velocity during the Matas test divided by that before the Matas test) was calculated. Additionally, using a head coil, 3 dimensional time-flight MR angiograms of the brain were obtained for each subject order to evaluate the anterior communicating artery. Six out of the 10 common carotid arteries were sufficiently compressed to stop blood flow. The relative mean ratio was 1.74 with a standard deviation of 0.36. The anterior communicating artery was visualized in all subjects. Increased blood volume is thus thought to maintain the blood supply of a cerebral hemisphere affected by compression of the common carotid artery via the anterior communicating artery. MR flow measurement using RACE before and during the Matas test seems to be a noninvasive method for evaluating cerebral collateral circulation via the circle of Willis. (author)

  10. A Modeling of Cerebral Blood Flow Changes due to Head Motion for fNIRS

    Science.gov (United States)

    Takahashi, Kosuke; Tanaka, Takayuki; Nara, Hiroyuki; Kaneko, Shun'ichi; Inoue, Masao; Shimizu, Shunji; Kojima, Satoru

    2013-04-01

    A method is proposed for measuring brain activity during exercises involving head motion by using functional near-infrared spectroscopy (fNIRS), which investigates cerebral hemodynamics. Obtaining measurements during exercise is difficult because cerebral blood flow changes due to the head motion component (HMC), in addition to neural activity. HMC is an undesirable artifact in the measurement of hemodynamic response caused by neural activity, and as such, it must be estimated and eliminated. In our experiments, cerebral blood flow and head motion were measured during repeated passive forward bending of the subjects. Head motion was measured by 3-D motion capture, and HMC was estimated by deriving a relation between head motion and cerebral blood flow, where the pitch angle was found to be suitable for estimating HMC. In this research, an assumption was made that cerebral blood flow caused by neural activity and that caused by postural change were additive, and thus HMC was eliminated by subtraction.

  11. Glial and neuronal control of brain blood flow

    DEFF Research Database (Denmark)

    Attwell, David; Buchan, Alastair M; Charpak, Serge;

    2010-01-01

    Blood flow in the brain is regulated by neurons and astrocytes. Knowledge of how these cells control blood flow is crucial for understanding how neural computation is powered, for interpreting functional imaging scans of brains, and for developing treatments for neurological disorders. It is now...

  12. Principal-component-analysis-based estimation of blood flow velocities using optical coherence tomography intensity signals

    OpenAIRE

    Mohan, Nishant; Vakoc, Benjamin

    2011-01-01

    The intensity signal in optical coherence tomography contains information about the translational velocity of scatterers, and can be used to quantify blood flow. We apply principal component analysis to efficiently extract this information. We also study use of nonuniform temporal sampling of the intensity signal to increase the range of quantifiable flow velocities. We demonstrate this technique in simulation, phantom and in vivo blood flow measurements, and highlight its potential to enable...

  13. Flow measurement by ultrasonic method

    International Nuclear Information System (INIS)

    An Ultrasonic Flow Meter (USFM) wasdeveloped to measure flow velocity of high temperature fluid in a pipe. To protect ultrasonic transducers from high temperature, guide rods were used. From the study on mechanical structure and acoustic property, the guide rod and the electronic circuit were improved to have capabilities of temperature compensation, quick response, high accuracy and not to be easily disturbed by bubbles contained in the fluid flow. Using a water flow loop, the test results proved the accuracy of +-1.0 percent and response time of 10 m sec

  14. Renal cortical and medullary blood flow responses to altered NO-availability in humans

    DEFF Research Database (Denmark)

    Damkjaer, Mads; Vafaee, Manoucher; Møller, Michael Lehd;

    2010-01-01

    of one voxel were eliminated stepwise from the external surface of the VOI ('voxel peeling'), and the blood flow subsequently determined in each new, reduced VOI. Blood flow in the shrinking volumes of interest (VOIs) decreased as the number of cycles of voxel peeling increased. After 4-5 cycles, blood...... flow was not reduced further by additional voxel peeling. This volume-insensitive flow was measured to be 2.30 ±0.17 ml·(g·min)(-1) during the control period; it increased during infusion of glyceryl nitrate to 2.97 ±0.18 ml·(g·min)(-1) (p...

  15. Blood Pressure Measurement Guidelines for Physical Therapists

    OpenAIRE

    Frese, Ethel M; Fick, Ann; Sadowsky, H. Steven

    2011-01-01

    Vital sign measurement and assessment are important components of the review of systems in a physical therapy examination for individuals with and without documented cardiopulmonary disease. The measurement of blood pressure gives the therapist information regarding the patient's baseline cardiovascular status, response to exercise/activity, and guides exercise prescription. Accurate measurement of blood pressure is critical for making appropriate clinical decisions especially if physical the...

  16. Pulsatile flow simulator for comparison of cardiac output measurements by electromagnetic flow meter and thermodilution.

    Science.gov (United States)

    Jebson, P J; Karkow, W S

    1986-01-01

    This study examined a pulsatile flow simulator for the purpose of evaluating two measurement devices, an extracorporeal flow probe with an electromagnetic flow meter and several thermodilution catheters. We measured the performance of these devices in a range of low to high flows. Using either saline or blood as a perfusate, we obtained different results with these fluids (p less than 0.001). Each catheter behaved in a linear manner, although variation occurred among the catheters with both saline (minimum slope 1.090, maximum slope 1.190) and blood (minimum slope 1.107, maximum slope 1.154). An increase in rate and stroke volumes of the simulator did not demonstrate an identifiable trend in error. The thermodilution catheters were most accurate at 5.0 L/min irrespective of rate, stroke volume, or perfusate used. In contrast, the electromagnetic flow meter accurately represented flows across the wide range of outputs examined (2.4 to 10.7 L/min). (Slope with saline 1.091, slope with blood 1.080) Throughout the range of flow, the flow meter gave a calibration line 5% higher with blood than with saline. The results indicate that accurate measurement of pulsatile blood flow can be achieved in vitro with an electromagnetic flow meter using saline as a perfusate, provided a correction factor is determined and applied to convert values for saline to accurate values for blood. PMID:2940345

  17. Lattice BGK Simulations of the Blood Flow in Elastic Vessels

    Institute of Scientific and Technical Information of China (English)

    LU Xiao-Yang; YI Hou-Hui; CHEN Ji-Yao; FANG Hai-Ping

    2006-01-01

    @@ The lattice Boltzmann method is applied to study the flow in elastic blood vessels. The volume-flow rate increases considerably when the compliance constant of the blood vessel is below a critical value. There is a region of the compliance constant in which the average volume-flow rate is dramatically enhanced. A harmonic perturbation of the pressure does not change the behaviour of the average volume-flow rate while the harmonic wave attenuates very quickly along the tube when the resonant period is close to that of the input wave. The model, together with the simulation results, is expected to be helpful to understand the mechanism of the blood volume-flow rate related to the compliance constant of the blood vessel, especially on the dependence of the flux of human blood vessel under weather changes, which has medical significance.

  18. Mammary blood flow regulation in the nursing rabbit

    Energy Technology Data Exchange (ETDEWEB)

    Katz, M.; Creasy, R.K.

    1984-11-01

    Cardiac output and mammary blood flow distribution prior to and after suckling were studied in 10 nursing rabbits by means of radionuclide-labeled microspheres. Suckling was followed by a 5.8% rise in cardiac output and a 20.4% rise in mammary blood flow. Determinations of intraglandular blood flow distribution have shown that there was a 43% increase in blood flow to the glands suckled from as compared to a 22.7% rise to the contralateral untouched glands and a 4.9% rise in the remainder of untouched glands. The conclusion is that a local mechanism may be involved in the regulation of mammary blood flow in the nursing rabbit.

  19. CALF BLOOD-FLOW AND POSTURE - DOPPLER ULTRASOUND CALIBRATED BY PLETHYSMOGRAPHY

    NARCIS (Netherlands)

    VANLEEUWEN, BE; LUBBERS, J; BARENDSEN, GJ; DEPATER, L

    1992-01-01

    A procedure was developed that enables measurement of rapid variations in calf blood flow during voluntary rhythmic contraction of the calf muscles in supine, sitting, and standing positions. During the exercise, maximum blood velocity is measured by Doppler ultrasound equipment in the popliteal art

  20. Interactive retinal blood flow analysis of the macular region.

    Science.gov (United States)

    Tian, Jing; Somfai, Gábor Márk; Campagnoli, Thalmon R; Smiddy, William E; Debuc, Delia Cabrera

    2016-03-01

    The study of retinal hemodynamics plays an important role to understand the onset and progression of diabetic retinopathy. In this work, we developed an interactive retinal analysis tool to quantitatively measure the blood flow velocity (BFV) and blood flow rate (BFR) in the macular region using the Retinal Function Imager (RFI). By employing a high definition stroboscopic fundus camera, the RFI device is able to assess retinal blood flow characteristics in vivo. However, the measurements of BFV using a user-guided vessel segmentation tool may induce significant inter-observer differences and BFR is not provided in the built-in software. In this work, we have developed an interactive tool to assess the retinal BFV and BFR in the macular region. Optical coherence tomography data was registered with the RFI image to locate the fovea accurately. The boundaries of the vessels were delineated on a motion contrast enhanced image and BFV was computed by maximizing the cross-correlation of pixel intensities in a ratio video. Furthermore, we were able to calculate the BFR in absolute values (μl/s). Experiments were conducted on 122 vessels from 5 healthy and 5 mild non-proliferative diabetic retinopathy (NPDR) subjects. The Pearson's correlation of the vessel diameter measurements between our method and manual labeling on 40 vessels was 0.984. The intraclass correlation (ICC) of BFV between our proposed method and built-in software was 0.924 and 0.830 for vessels from healthy and NPDR subjects, respectively. The coefficient of variation between repeated sessions was reduced significantly from 22.5% to 15.9% in our proposed method (p<0.001).

  1. Measurements of diagnostic examination performance and correlation analysis using microvascular leakage, cerebral blood volume, and blood flow derived from 3T dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging in glial tumor grading

    International Nuclear Information System (INIS)

    To assess the diagnostic accuracy of microvascular leakage (MVL), cerebral blood volume (CBV) and blood flow (CBF) values derived from dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging (DSC-MR imaging) for grading of cerebral glial tumors, and to estimate the correlation between vascular permeability/perfusion parameters and tumor grades. A prospective study of 79 patients with cerebral glial tumors underwent DSC-MR imaging. Normalized relative CBV (rCBV) and relative CBF (rCBF) from tumoral (rCBVt and rCBFt), peri-enhancing region (rCBVe and rCBFe), and the value in the tumor divided by the value in the peri-enhancing region (rCBVt/e and rCBFt/e), as well as MVL, expressed as the leakage coefficient K2 were calculated. Hemodynamic variables and tumor grades were analyzed statistically and with Pearson correlations. Receiver operating characteristic (ROC) curve analyses were also performed for each of the variables. The differences in rCBVt and the maximum MVL (MVLmax) values were statistically significant among all tumor grades. Correlation analysis using Pearson was as follows: rCBVt and tumor grade, r = 0.774; rCBFt and tumor grade, r = 0.417; MVLmax and tumor grade, r = 0.559; MVLmax and rCBVt, r = 0.440; MVLmax and rCBFt, r = 0.192; and rCBVt and rCBFt, r = 0.605. According to ROC analyses for distinguishing tumor grade, rCBVt showed the largest areas under ROC curve (AUC), except for grade III from IV. Both rCBVt and MVLmax showed good discriminative power in distinguishing all tumor grades. rCBVt correlated strongly with tumor grade; the correlation between MVLmax and tumor grade was moderate. (orig.)

  2. Measurements of diagnostic examination performance and correlation analysis using microvascular leakage, cerebral blood volume, and blood flow derived from 3T dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging in glial tumor grading

    Energy Technology Data Exchange (ETDEWEB)

    Server, Andres; Nakstad, Per H. [Oslo University Hospital-Ullevaal, Section of Neuroradiology, Department of Radiology and Nuclear Medicine, Oslo (Norway); University of Oslo, Oslo (Norway); Graff, Bjoern A. [Oslo University Hospital-Ullevaal, Department of Radiology and Nuclear Medicine, Oslo (Norway); Orheim, Tone E.D.; Gadmar, Oeystein B. [Oslo University Hospital, Interventional Centre, Oslo (Norway); Schellhorn, Till [Oslo University Hospital-Ullevaal, Section of Neuroradiology, Department of Radiology and Nuclear Medicine, Oslo (Norway); Josefsen, Roger [Oslo University Hospital-Ullevaal, Department of Neurosurgery, Oslo (Norway)

    2011-06-15

    To assess the diagnostic accuracy of microvascular leakage (MVL), cerebral blood volume (CBV) and blood flow (CBF) values derived from dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging (DSC-MR imaging) for grading of cerebral glial tumors, and to estimate the correlation between vascular permeability/perfusion parameters and tumor grades. A prospective study of 79 patients with cerebral glial tumors underwent DSC-MR imaging. Normalized relative CBV (rCBV) and relative CBF (rCBF) from tumoral (rCBVt and rCBFt), peri-enhancing region (rCBVe and rCBFe), and the value in the tumor divided by the value in the peri-enhancing region (rCBVt/e and rCBFt/e), as well as MVL, expressed as the leakage coefficient K{sub 2} were calculated. Hemodynamic variables and tumor grades were analyzed statistically and with Pearson correlations. Receiver operating characteristic (ROC) curve analyses were also performed for each of the variables. The differences in rCBVt and the maximum MVL (MVL{sub max}) values were statistically significant among all tumor grades. Correlation analysis using Pearson was as follows: rCBVt and tumor grade, r = 0.774; rCBFt and tumor grade, r = 0.417; MVL{sub max} and tumor grade, r = 0.559; MVL{sub max} and rCBVt, r = 0.440; MVL{sub max} and rCBFt, r = 0.192; and rCBVt and rCBFt, r = 0.605. According to ROC analyses for distinguishing tumor grade, rCBVt showed the largest areas under ROC curve (AUC), except for grade III from IV. Both rCBVt and MVL{sub max} showed good discriminative power in distinguishing all tumor grades. rCBVt correlated strongly with tumor grade; the correlation between MVL{sub max} and tumor grade was moderate. (orig.)

  3. Design and Simulation of Axial Flow Maglev Blood Pump

    OpenAIRE

    Huachun Wu; Ziyan Wang; Xujun Lv

    2011-01-01

    The axial flow maglev blood pump (AFMBP) has become a global research focus and emphasis for artificial ventricular assist device, which has no mechanical contact, mechanical friction, compact structure and light weight, can effectively solve thrombus and hemolysis. Magnetic suspension and impeller is two of the important parts in the axial flow maglev blood pump, and their structure largely determines the blood pump performance. The research adopts electromagnetic and fluid finite element an...

  4. Comparison of xenon enhanced CT (XeCT) and I-123 iodoamphetamine (SPECT/IMP) techniques for measurement of regional cerebral blood flow (rCBF)

    International Nuclear Information System (INIS)

    An ongoing prospective study measuring rCBF by XeCT(20 patients) and SPECT/IMP (84 patients) to date includes 9 patients examined by both techniques. XeCT was done as 3 contiguous transaxial tomograms using a scanner (GE 9800) equipped with dynamic imaging capability and a gas delivery system for inspiring 30% Xenon. SPECT/IMP was done 20 minutes after injection of 3-5 mCi of IMP, obtaining 64 views over 360 degrees, 40 sec./view, with either a GE 400T or 400ACT. SPECT/IMP images obtained with the 400ACT camera (specially designed for head work) were superior to those obtained with the older camera. For all 9 cases, both techniques demonstrated flow abnormalities at all sites of infarction identified by conventional CT (TCT): 1 patient with normal TCT also had normal rCBF examinations. Furthermore, 8 of 9 cases showed evidence of ischemia (regions with normal TCT and abnormal rCBF measurements) by both techniques

  5. POSIVA groundwater flow measuring techniques

    Energy Technology Data Exchange (ETDEWEB)

    Oehberg, A. [Saanio and Riekkola Consulting Engineers, Helsinki (Finland); Rouhiainen, P. [PRG-Tec Oy (Finland)

    2000-08-01

    Posiva Oy has carried out site characterisation for the final disposal of spent nuclear fuel in Finland since 1987. To meet the demanding needs to measure the hydraulic parameters in bedrock Posiva launched development of new flowmeter techniques including measuring methods and equipment in co-operation with PRG-Tec Oy. The techniques have been tested and used in the ongoing site investigations in Finland, in the underground Hard Rock Laboratory (HRL) at Aespoe in Sweden and in URL in Canada. The new methods are called difference flow and transverse flow methods. The difference flow method includes two modes, normal and detailed flow logging methods. In the normal mode the flow rate measurement is based on thermal pulse and thermal dilution methods, in the detailed logging mode only on thermal dilution method. The measuring ranges for flow rate with thermal pulse and dilution methods are 0.1-10 ml/min and 2-5000 ml/min, respectively. The difference flow method(normal mode) for small flows (0.1-10 ml/min) is based on measuring the pulse transit time and direction of a thermal pulse in the sensor. For high flows (2-5000 ml/min) the method is based on thermal dilution rate of a sensor. Direction is measured with monitoring thermistors. Inflow or outflow in the test interval is created due to natural or by pumping induced differences between heads in the borehole water and groundwater around the borehole. The single point resistance (and the temperature of borehole water) measurement is carried out simultaneously with the difference flow measurements, both in normal and detailed flow logging modes, while the tool is moving. The result is utilised for checking the exact depth of the tool. As the result a continuous log is obtained from which single fractures can be detected. The transverse flowmeter is able to measure the groundwater flow across a borehole. A special packer system guides the flow through the flow sensors. Four inflatable seals between conventional

  6. POSIVA groundwater flow measuring techniques

    International Nuclear Information System (INIS)

    Posiva Oy has carried out site characterisation for the final disposal of spent nuclear fuel in Finland since 1987. To meet the demanding needs to measure the hydraulic parameters in bedrock Posiva launched development of new flowmeter techniques including measuring methods and equipment in co-operation with PRG-Tec Oy. The techniques have been tested and used in the ongoing site investigations in Finland, in the underground Hard Rock Laboratory (HRL) at Aespoe in Sweden and in URL in Canada. The new methods are called difference flow and transverse flow methods. The difference flow method includes two modes, normal and detailed flow logging methods. In the normal mode the flow rate measurement is based on thermal pulse and thermal dilution methods, in the detailed logging mode only on thermal dilution method. The measuring ranges for flow rate with thermal pulse and dilution methods are 0.1-10 ml/min and 2-5000 ml/min, respectively. The difference flow method(normal mode) for small flows (0.1-10 ml/min) is based on measuring the pulse transit time and direction of a thermal pulse in the sensor. For high flows (2-5000 ml/min) the method is based on thermal dilution rate of a sensor. Direction is measured with monitoring thermistors. Inflow or outflow in the test interval is created due to natural or by pumping induced differences between heads in the borehole water and groundwater around the borehole. The single point resistance (and the temperature of borehole water) measurement is carried out simultaneously with the difference flow measurements, both in normal and detailed flow logging modes, while the tool is moving. The result is utilised for checking the exact depth of the tool. As the result a continuous log is obtained from which single fractures can be detected. The transverse flowmeter is able to measure the groundwater flow across a borehole. A special packer system guides the flow through the flow sensors. Four inflatable seals between conventional

  7. PERFORMANCE MODELING AND ANALYSIS OF BLOOD FLOW IN ELASTIC ARTERIES

    Institute of Scientific and Technical Information of China (English)

    Anil Kumar; C.L. Varshney; G.C. Sharma

    2005-01-01

    Two different non-Newtonian models for blood flow are considered, first a simple power law model displaying shear thinning viscosity, and second a generalized Maxwell model displaying both shear thinning viscosity and oscillating flow viscous-elasticity. These models are used along with a Newtonian model to study sinusoidal flow of blood in rigid and elastic straight arteries in the presence of magnetic field. The elasticity of blood does not appear to influence its flow behavior under physiological conditions in the large arteries,purely viscous shear thinning model should be quite realistic for simulating blood flow under these conditions. On using the power law model with high shear rate for sinusoidal flow simulation in elastic arteries, the mean and amplitude of the flow rate were found to be lower for a power law fluid compared to Newtonian fluid for the same pressure gradient. The governing equations have been solved by Crank-Niclson scheme. The results are interpreted in the context of blood in the elastic arteries keeping the magnetic effects in view. For physiological flow simulation in the aorta, an increase in mean wall shear stress, but a reduction in peak wall shear stress were observed for power law model compared to a Newtonian fluid model for matched flow rate wave form. Blood flow in the presence of transverse magnetic field in an elastic artery is investigated and the influence of factors such as morphology and surface irregularity is evaluated.

  8. Nocturnal variations in subcutaneous blood flow rate in lower leg of normal human subjects

    DEFF Research Database (Denmark)

    Sindrup, J H; Kastrup, J; Jørgensen, B;

    1991-01-01

    , an additional blood flow rate increment of considerable magnitude was observed. The mean increase was 84%, but in several cases a greater than 200% increment was measured (maximum 244%). The intra-individual coefficient of variation for the nocturnal blood flow response was in triplicate measurements 25% (n = 9...... in central and local postural sympathetic vasoconstrictor activity. During sleep, characteristic variations in subcutaneous blood flow were disclosed. The 133Xe washout curve could be divided into three segments with significantly different slopes. Approximately 90 min after the subject went to sleep...

  9. Cerebral blood flow, oxygen and glucose metabolism with PET in progressive supranuclear palsy

    Energy Technology Data Exchange (ETDEWEB)

    Otsuka, Makoto; Ichiya, Yuici; Kuwabara, Yasuo (Kyushu Univ., Fukuoka (Japan). Faculty of Medicine) (and others)

    1989-11-01

    Cerebral blood flow, cerebral oxygen metabolic rate and cerebral glucose metabolic rate were measured with positron emission tomography (PET) in four patients with progressive supranuclear palsy (PSP). Decreased blood flow and hypometabolism of oxygen and glucose were found in both subcortical and cortical regions, particularly in the striatum including the head of the caudate nucleus and the frontal cortex. The coupling between blood flow and metabolism was preserved even in the regions which showed decreased blood flow and hypometabolism. These findings indicated the hypofunction, as revealed by decreased blood flow and hypometablolism on PET, both in the striatum and the frontal cortex, and which may underlie the pathophysiological mechanism of motor and mental disturbance in PSP. (author).

  10. Cerebral blood flow, oxygen and glucose metabolism with PET in progressive supranuclear palsy

    International Nuclear Information System (INIS)

    Cerebral blood flow, cerebral oxygen metabolic rate and cerebral glucose metabolic rate were measured with positron emission tomography (PET) in four patients with progressive supranuclear palsy (PSP). Decreased blood flow and hypometabolism of oxygen and glucose were found in both subcortical and cortical regions, particularly in the striatum including the head of the caudate nucleus and the frontal cortex. The coupling between blood flow and metabolism was preserved even in the regions which showed decreased blood flow and hypometabolism. These findings indicated the hypofunction, as revealed by decreased blood flow and hypometablolism on PET, both in the striatum and the frontal cortex, and which may underlie the pathophysiological mechanism of motor and mental disturbance in PSP. (author)

  11. Basic taste stimuli elicit unique responses in facial skin blood flow.

    Directory of Open Access Journals (Sweden)

    Hideaki Kashima

    Full Text Available Facial expression changes characteristically with the emotions induced by basic tastes in humans. We tested the hypothesis that the five basic tastes also elicit unique responses in facial skin blood flow. Facial skin blood flow was measured using laser speckle flowgraphy in 16 healthy subjects before and during the application of basic taste stimuli in the oral cavity for 20 s. The skin blood flow in the eyelid increased in response to sweet and umami taste stimuli, while that in the nose decreased in response to a bitter stimulus. There was a significant correlation between the subjective hedonic scores accompanying these taste stimuli and the above changes in skin blood flow. These results demonstrate that sweet, umami, and bitter tastes induce unique changes in facial skin blood flow that reflect subjective hedonic scores.

  12. Interscapular brown adipose tissue blood flow in the rat. Determination with 133xenon clearance compared to the microsphere method

    DEFF Research Database (Denmark)

    Astrup, A; Bülow, J; Madsen, J

    1984-01-01

    a close correlation to the blood flow values determined with microspheres. Y = 0.98. X + 0.15 (r = 0.96, P less than 0.001). The Xe clearance method has the advantages compared to the microsphere technique that it permits continuous monitoring of the blood flow and does not require the sacrifice......The xenon clearance method was adapted to continuous measurement of interscapular brown adipose tissue (ISBAT) blood flow in anesthetized rats. The ISBAT-blood partition coefficient for xenon was determined to 3.6 ml X g-1. The blood flow values obtained by Xe clearance were compared with flow...

  13. Structured Tree Outflow Condition for Blood Flow in Arteries

    Science.gov (United States)

    Olufsen, Mette

    1998-11-01

    Modeling blood flow and especially propagation of the pulse wave in the systemic arteries is of interests to the medical society because of the significance of the dicrotic wave. The pulse wave propagating along the larger arteries is reflected because of tapering and branching of the vessels, as well as the peripheral resistance, which is mainly stemming from the smaller arteries and arterioles. In order to avoid artificial reflections it is important to determine a boundary condition, representing the smaller arteries and arterioles, which is physiologically correct. In this work we have proposed a boundary condition based on a structured tree model. The result will be compared both with other modeling approaches as well as with results from measurements of flow and pressure at a number of locations along the larger arteries. The model for the larger arteries is based on the axisymmetrical Navier Stokes equations where the blood is assumed Newtonian and incompressible and the vessels are tapering. In the structured tree the model is based on a linearization of the axisymmetrical Navier-Stokes equations. The reason for setting up a structured tree is that the smaller arteries consist of an almost binary tree. Furthermore, the role of the smaller arteries is to allow blood perfusion of specific tissues. This is done in a structured and optimal way such that the smaller arteries cover the tissue evenly using a minimization principle.

  14. Adrenergically stimulated blood flow in brown adipose tissue is not dependent on thermogenesis.

    Science.gov (United States)

    Abreu-Vieira, Gustavo; Hagberg, Carolina E; Spalding, Kirsty L; Cannon, Barbara; Nedergaard, Jan

    2015-05-01

    Brown adipose tissue (BAT) thermogenesis relies on blood flow to be supplied with nutrients and oxygen and for the distribution of the generated heat to the rest of the body. Therefore, it is fundamental to understand the mechanisms by which blood flow is regulated and its relation to thermogenesis. Here, we present high-resolution laser-Doppler imaging (HR-LDR) as a novel method for noninvasive in vivo measurement of BAT blood flow in mice. Using HR-LDR, we found that norepinephrine stimulation increases BAT blood flow in a dose-dependent manner and that this response is profoundly modulated by environmental temperature acclimation. Surprisingly, we found that mice lacking uncoupling protein 1 (UCP1) have fully preserved BAT blood flow response to norepinephrine despite failing to perform thermogenesis. BAT blood flow was not directly correlated to systemic glycemia, but glucose injections could transiently increase tissue perfusion. Inguinal white adipose tissue, also known as a brite/beige adipose tissue, was also sensitive to cold acclimation and similarly increased blood flow in response to norepinephrine. In conclusion, using a novel noninvasive method to detect BAT perfusion, we demonstrate that adrenergically stimulated BAT blood flow is qualitatively and quantitatively fully independent of thermogenesis, and therefore, it is not a reliable parameter for the estimation of BAT activation and heat generation.

  15. Effects of inspiratory resistance, inhaled beta-agonists and histamine on canine tracheal blood flow

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, W.T.; Baile, E.M.; Brancatisano, A.; Pare, P.D.; Engel, L.A. (Dept. of Respiratory Medicine, Westmead Hospital, Westmead, NSW (Australia))

    1992-01-01

    Tracheobronchial blood flow is potentially important in asthma as it could either influence the clearance of mediators form the airways, thus affecting the duration and severity of bronchoispasm, or enhance oedema formation with a resultant increase in airflow obstruction. In anaesthetized dogs, spontaneously breathing via a tracheostomy, we investigated the effects of three interventions which are relevant to acute asthma attacks and could potentially influence blood flow and its distribution to the mucosa and remaining tissues of the trachea: (1) increased negative intrathoracic pressure swings (-25[+-]1 cmH[sub 2]O) induced by an inspiratory resistance; (2) variable inhaled doses of a beta-adrenoceptor-agonist (terbutaline); and (3) aerosolized histamine sufficient to produce a threefold increase in pulmonary resistance. Microspheres labelled with different radioisotopes were used to measure blood flow. Resistive breathing did not influence tracheobronchial blood flow. Following a large dose of terbutaline, mucosal blood flow (Qmb) increased by 50%. After inhaled histamine, Qmb reached 265% of the baseline value. We conclude that, whereas increased negative pressure swings do not influence tracheobronchial blood flow or its distribution, inhalation of aerosolized terbutaline, corresponding to a conventionally nebulized dose, increases mucosal blood flow. Our results also confirm that inhaled histamine, in a dose sufficient to produce moderate bronchoconstriction, increases tracheal mucosal blood flow in the area of deposition. (au).

  16. Effect of labetalol on cerebral blood flow and middle cerebral arterial flow velocity in healthy volunteers

    DEFF Research Database (Denmark)

    Schroeder, T; Schierbeck, Jens; Howardy, P;

    1991-01-01

    The effect of labetalol, a combined alpha- and beta-adrenoceptor antagonist, on the cerebral circulation was investigated in 7 normotensive subjects. Cerebral blood flow (CBF) was measured with the intravenous 133Xe method and mean flow velocity (Vmean) in the middle cerebral artery was determined...... using transcranial Doppler (TCD) ultrasound. Examination was performed before and then 15, 60 and 120 min after 0.75 mg/kg i.v. labetalol. Reactivity to inhalation of 5% CO2 in air was studied before, and again 90 min after labetalol administration. Neither CBF nor Vmean changed following labetalol...

  17. Spiral blood flow in aorta-renal bifurcation models.

    Science.gov (United States)

    Javadzadegan, Ashkan; Simmons, Anne; Barber, Tracie

    2016-01-01

    The presence of a spiral arterial blood flow pattern in humans has been widely accepted. It is believed that this spiral component of the blood flow alters arterial haemodynamics in both positive and negative ways. The purpose of this study was to determine the effect of spiral flow on haemodynamic changes in aorta-renal bifurcations. In this regard, a computational fluid dynamics analysis of pulsatile blood flow was performed in two idealised models of aorta-renal bifurcations with and without flow diverter. The results show that the spirality effect causes a substantial variation in blood velocity distribution, while causing only slight changes in fluid shear stress patterns. The dominant observed effect of spiral flow is on turbulent kinetic energy and flow recirculation zones. As spiral flow intensity increases, the rate of turbulent kinetic energy production decreases, reducing the region of potential damage to red blood cells and endothelial cells. Furthermore, the recirculation zones which form on the cranial sides of the aorta and renal artery shrink in size in the presence of spirality effect; this may lower the rate of atherosclerosis development and progression in the aorta-renal bifurcation. These results indicate that the spiral nature of blood flow has atheroprotective effects in renal arteries and should be taken into consideration in analyses of the aorta and renal arteries. PMID:26414530

  18. Detection of Site-Specific Blood Flow Variation in Humans during Running by a Wearable Laser Doppler Flowmeter

    Directory of Open Access Journals (Sweden)

    Wataru Iwasaki

    2015-10-01

    Full Text Available Wearable wireless physiological sensors are helpful for monitoring and maintaining human health. Blood flow contains abundant physiological information but it is hard to measure blood flow during exercise using conventional blood flowmeters because of their size, weight, and use of optic fibers. To resolve these disadvantages, we previously developed a micro integrated laser Doppler blood flowmeter using microelectromechanical systems technology. This micro blood flowmeter is wearable and capable of stable measurement signals even during movement. Therefore, we attempted to measure skin blood flow at the forehead, fingertip, and earlobe of seven young men while running as a pilot experiment to extend the utility of the micro blood flowmeter. We measured blood flow in each subject at velocities of 6, 8, and 10 km/h. We succeeded in obtaining stable measurements of blood flow, with few motion artifacts, using the micro blood flowmeter, and the pulse wave signal and motion artifacts were clearly separated by conducting frequency analysis. Furthermore, the results showed that the extent of the changes in blood flow depended on the intensity of exercise as well as previous work with an ergometer. Thus, we demonstrated the capability of this wearable blood flow sensor for measurement during exercise.

  19. Working meeting on blood pressure measurement: suggestions for measuring blood pressure to use in populations surveys.

    Science.gov (United States)

    2003-11-01

    As part of the Pan American Hypertension Initiative (PAHI), the Pan American Health Organization and the National Heart, Lung, and Blood Institute of the National Institutes of Health of the United States of America conducted a working meeting to discuss blood pressure (BP) measurement methods used in various hypertension prevalence surveys and clinical trials, with the objective of developing a BP measurement protocol for use in hypertension prevalence surveys in the Americas. No such common protocol has existed in the Americas, so it has been difficult to compare hypertension prevention and intervention strategies. This piece describes a proposed standard method for measuring blood pressure for use in population surveys in the Region of the Americas. The piece covers: considerations for developing a common blood pressure measurement protocol, critical issues in measuring blood pressure in national surveys, minimum procedures for blood pressure measurement during surveillance, and quality assessment of blood pressure.

  20. Estimation of vessel diameter and blood flow dynamics from laser speckle images

    DEFF Research Database (Denmark)

    Postnov, Dmitry D.; Tuchin, Valery V.; Sosnovtseva, Olga

    2016-01-01

    Laser speckle imaging is a rapidly developing method to study changes of blood velocity in the vascular networks. However, to assess blood flow and vascular responses it is crucial to measure vessel diameter in addition to blood velocity dynamics. We suggest an algorithm that allows for dynamical...... masking of a vessel position and measurements of it's diameter from laser speckle images. This approach demonstrates high reliability and stability....

  1. Estimation of vessel diameter and blood flow dynamics from laser speckle images

    Science.gov (United States)

    Postnov, Dmitry D.; Tuchin, Valery V.; Sosnovtseva, Olga

    2016-01-01

    Laser speckle imaging is a rapidly developing method to study changes of blood velocity in the vascular networks. However, to assess blood flow and vascular responses it is crucial to measure vessel diameter in addition to blood velocity dynamics. We suggest an algorithm that allows for dynamical masking of a vessel position and measurements of it’s diameter from laser speckle images. This approach demonstrates high reliability and stability.

  2. ANALYSIS OF PULSATILE BLOOD FLOW IN AXIALLY MOVING ARTERIES

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In order to study motional properties of pulsatile blood flow in axially moving arteries, the authors derived some expressions of the pulsatile blood flow from the basic equations of motion for blood and vascular walls, including an axial blood velocity equation, a flow rate equation and a wall shear stress equation, which described not only the overall axial movement of the arteries but also the elastic properties of the vascular walls, discussed the effects of the arterial wall elasticity on the wall shear stress in coronary arteries in terms of these expressions, and analyzed changes of motional properties of pulsatile blood flow between an elastic arterial tube model and a rigid tube model. The results proved the inference by J.E. Moore Jr. et al. (1994) that the axial movement of arteries be as important in determining coronary artery hemodynamics as the elastic property of the vascular wall.

  3. On the flow dependency of the electrical conductivity of blood

    NARCIS (Netherlands)

    Hoetink, AE; Faes, TJC; Visser, KR; Heethaar, RM

    2004-01-01

    Experiments presented in the literature show that the electrical conductivity of flowing blood depends on flow velocity. The aim of this study is to extend the Maxwell-Fricke theory, developed for a dilute suspension of ellipsoidal particles in an electrolyte, to explain this flow dependency of the

  4. Cerebral blood flow and metabolism during exercise: implications for fatigue

    NARCIS (Netherlands)

    N.H. Secher; T. Seifert; J.J. van Lieshout

    2008-01-01

    During exercise: the Kety-Schmidt-determined cerebral blood flow (CBF) does not change because the jugular vein is collapsed in the upright position. In contrast, when CBF is evaluated by (133)Xe clearance, by flow in the internal carotid artery, or by flow velocity in basal cerebral arteries, a app

  5. Holographic laser Doppler imaging of microvascular blood flow

    CERN Document Server

    Magnain, C; Boucneau, T; Simonutti, M; Ferezou, I; Rancillac, A; Vitalis, T; Sahel, J A; Paques, M; Atlan, M

    2014-01-01

    We report on local superficial blood flow monitoring in biological tissue from laser Doppler holographic imaging. In time averaging recording conditions, holography acts as a narrowband bandpass filter, which, combined with a frequency shifted reference beam, permits frequency selective imaging in the radiofrequency range. These Doppler images are acquired with an off axis Mach Zehnder interferometer. Microvascular hemodynamic components mapping is performed in the cerebral cortex of the mouse and the eye fundus of the rat with near-infrared laser light without any exogenous marker. These measures are made from a basic inverse method analysis of local first order optical fluctuation spectra at low radiofrequencies, from 0 Hz to 100 kHz. Local quadratic velocity is derived from Doppler broadenings induced by fluid flows, with elementary diffusing wave spectroscopy formalism in backscattering configuration. We demonstrate quadratic mean velocity assessment in the 0.1 to 10 millimeters per second range in vitro ...

  6. Skin temperature and subcutaneous adipose blood flow in man

    DEFF Research Database (Denmark)

    Astrup, A; Bülow, J; Madsen, J

    1980-01-01

    correlation between skin temperature and ATBF. In the range from 25 to 37 degrees CATBF increased 9% of the control flow on average per centigrade increase in skin temperature. ATBF at the control side was uninfluenced by the contralateral variations in skin temperature. Although no better correlation could......The abdominal subcutaneous adipose tissue blood flow (ATBF) was measured bilaterally by the 133Xe washout method. At one side of the skin (epicutaneous) temperature was varied with a temperature blanket, the other side served as control. There was a significant (P less than 0.001) positive...... be demonstrated between ATBF and subcutaneous temperature than between ATBF and skin temperature, arguments are presented in favour of the hypothesis that ATBF is influenced by the subcutaneous temperature rather than via reflexes from the skin. Infiltration of the 133Xe depots with 20 microgram...

  7. Effects of non Newtonian spiral blood flow through arterial stenosis

    Science.gov (United States)

    Hasan, Md. Mahmudul; Maruf, Mahbub Alam; Ali, Mohammad

    2016-07-01

    The spiral component of blood flow has both beneficial and detrimental effects in human circulatory system. A numerical investigation is carried out to analyze the effect of spiral blood flow through an axisymmetric three dimensional artery having 75% stenosis at the center. Blood is assumed as a Non-Newtonian fluid. Standard k-ω model is used for the simulation with the Reynolds number of 1000. A parabolic velocity profile with spiral flow is used as inlet boundary condition. The peak values of all velocity components are found just after stenosis. But total pressure gradually decreases at downstream. Spiral flow of blood has significant effects on tangential component of velocity. However, the effect is mild for radial and axial velocity components. The peak value of wall shear stress is at the stenosis zone and decreases rapidly in downstream. The effect of spiral flow is significant for turbulent kinetic energy. Detailed investigation and relevant pathological issues are delineated throughout the paper.

  8. The effect of ergotamine and dihydroergotamine on cerebral blood flow in man

    DEFF Research Database (Denmark)

    Andersen, A R; Tfelt-Hansen, P; Lassen, N A

    1987-01-01

    The effects of ergotamine and dihydroergotamine on cerebral blood flow was investigated 4 hours after i.v. injection as these drugs might be of importance for migraine treatment. Eight normal male volunteers (not suffering from migraine) received 0.5 mg ergotamine and 1 mg dihydroergotamine i.......v. Cerebral blood flow was measured by the xenon-133 inhalation method and single-photon-emission computerized tomography before and after intravenous acetazolamide administration (1 g). Cerebral blood flow was measured before and 4 hours after ergotamine and dihydroergotamine administration. Strain......-gauge measurements of toe-arm systolic gradients were used to monitor the effect of the drug on leg arteries. Mean hemispheric and regional cerebral blood flow was unchanged after either drug (mean +/- SEM, ml/100 g/min): for ergotamine, 57 +/- 3 before and 57 +/- 3 at 4 hours; for dihydroergotamine, 54 +/- 2 before...

  9. The Utility of Cerebral Blood Flow Assessment in TBI.

    Science.gov (United States)

    Akbik, Omar S; Carlson, Andrew P; Krasberg, Mark; Yonas, Howard

    2016-08-01

    Over the past few decades, intracranial monitoring technologies focused on treating and preempting secondary injury after traumatic brain injury (TBI) have experienced considerable growth. A physiological measure fundamental to the management of these patients is cerebral blood flow (CBF), which may be determined directly or indirectly. Direct measurement has proven difficult previously; however, invasive and non-invasive CBF monitors are now available. This article reviews the history of CBF measurements in TBI as well as the role of CBF in pathologies associated with TBI, such as cerebral autoregulation, hyperemia, and cortical spreading depression. The limitations of various CBF monitors are reviewed in order to better understand their role in TBI management. PMID:27315250

  10. Altered Cerebral Blood Flow Covariance Network in Schizophrenia.

    Science.gov (United States)

    Liu, Feng; Zhuo, Chuanjun; Yu, Chunshui

    2016-01-01

    Many studies have shown abnormal cerebral blood flow (CBF) in schizophrenia; however, it remains unclear how topological properties of CBF network are altered in this disorder. Here, arterial spin labeling (ASL) MRI was employed to measure resting-state CBF in 96 schizophrenia patients and 91 healthy controls. CBF covariance network of each group was constructed by calculating across-subject CBF covariance between 90 brain regions. Graph theory was used to compare intergroup differences in global and nodal topological measures of the network. Both schizophrenia patients and healthy controls had small-world topology in CBF covariance networks, implying an optimal balance between functional segregation and integration. Compared with healthy controls, schizophrenia patients showed reduced small-worldness, normalized clustering coefficient and local efficiency of the network, suggesting a shift toward randomized network topology in schizophrenia. Furthermore, schizophrenia patients exhibited altered nodal centrality in the perceptual-, affective-, language-, and spatial-related regions, indicating functional disturbance of these systems in schizophrenia. This study demonstrated for the first time that schizophrenia patients have disrupted topological properties in CBF covariance network, which provides a new perspective (efficiency of blood flow distribution between brain regions) for understanding neural mechanisms of schizophrenia.

  11. Forearm blood flow responses of offspring of hypertensives to an extended stress task.

    Science.gov (United States)

    Ditto, B; Miller, S B

    1989-02-01

    The forearm blood flow and other cardiovascular responses of 10 healthy young men with a parental history of hypertension to an extended laboratory stressor were compared with the responses of 10 age-matched men with normotensive parents. To eliminate the effects of the anticipation of stress on baseline measures, all subjects participated in a separate 1-hour counterbalanced baseline session in which no stress was presented. There were no significant differences between the two groups in resting blood pressure, heart rate, blood volume pulse, forearm blood flow and vascular resistance, and self-report anxiety, although offspring of hypertensive parents exhibited marginally greater (p = 0.08) forearm blood flow at rest. During the stress session, subjects played video games for 1 hour and avoided mild electric shocks depending on performance. Offspring of hypertensive parents exhibited significantly greater heart rate (+19 +/- 6 vs. +3 +/- 2%), forearm blood flow (+52 +/- 14 vs. +9 +/- 4%), and self-report anxiety (+25 +/- 6 vs. +9 +/- 3%) responses to the task. There were no significant group differences in blood pressure response to the task. Significant positive correlations between forearm blood flow and heart rate responses to the task were observed. These findings extend earlier results that suggested healthy young offspring of hypertensive and normotensive parents may exhibit different patterns of hemodynamic response to stress in the absence of differences in resting blood pressure or blood pressure responsiveness to stress. PMID:2914737

  12. The Effect of Doppler Phenomenon on the Speed of Blood Flow

    Directory of Open Access Journals (Sweden)

    Ghaidaa Abdulrahman Khalid

    2012-01-01

    Full Text Available This research studying the phenomenon of Doppler (frequency Doppler as a method through which the direction and speed of the blood cells flows in blood vessels wear measured. This Doppler frequency is relied upon in medicine for measuring the speed of blood flow, because the blood flow is an important concept from the concepts of medicine. It represents the function and efficient of the heart and blood vessels in the body so any defect in this function will appear as a change in the speed of blood flow from the normal value assumed. As this speed changes alot in cases of disease and morbidity of the heart, so in order to identify the effect of changing the Doppler frequency on the speed of blood flow and the relationship of this frequency with the angles of transitions and receptions and the effect of changing the ultrasound transmitted frequencies on the measured velocities .The Doppler ultrasound system has been used which is more efficient and easier to be widely used as a practical application in Al Yarmouk Teaching Hospital on two subjects. The normal had a natural medical history in the blood vessels, and abnormal had carotid artery stenosis. This device will give the flow velocity of blood in the blood vessels which is useful to the examiner, the equation of Doppler as a mathematical model in the research is adopted the measured speed to clarify the amount of change in the frequency (shift in frequency. This speed was measured in five different blood vessels, large arteries (abdominal aorta and carotid artery in the neck and large veins (the inferior vena cava across the abdomen and the external Jugular vein in the neck and capillaries in the hand and fingers. Then using the measured velocities in these vessels the Doppler frequency was calculated from this mathematical model using MATLAB program, was found that as velocity of the blood increases, so does the Doppler frequency and vice versa. The greater the value of the Doppler angle

  13. Resting Blood Flow in the Skin: Does It Exist, and What Is the Influence of Temperature, Aging, and Diabetes?

    OpenAIRE

    Petrofsky, Jerrold Scott

    2012-01-01

    Measurement of resting blood flow to the skin and other organs is an important indicator of health and disease and a way to assess the reaction to various stimuli and pharmaceutical interventions. However, unlike plasma ions such as sodium or potassium, it is difficult to determine what the proper value for resting blood flow really is. Part of the problem is in the measurement of blood flow; various techniques yield very different measures of skin blood flow even in the same area. Even if th...

  14. The effects of fenoldopam on coronary conduit blood flow after coronary artery bypass graft surgery.

    LENUS (Irish Health Repository)

    Halpenny, M

    2012-02-03

    OBJECTIVE: To quantify the effects of fenoldopam, 0.1 microg\\/kg\\/min, on left internal mammary artery (LIMA) and saphenous vein blood flow after coronary anastomosis. DESIGN: Prospective, randomized, double-blind, placebo-controlled trial. SETTING: University teaching hospital, single institution. PARTICIPANTS: Thirty-one American Society of Anesthesiologists III patients undergoing elective coronary revascularization. INTERVENTIONS: A perivascular ultrasonic flow probe (Linton Instrumentation, Norfolk, UK) was placed around the LIMA and saphenous vein graft after coronary anastomosis. MEASUREMENTS AND MAIN RESULTS: Immediately before and at 5-minute intervals for 15 minutes after starting the infusion, blood flow was measured in the LIMA and one saphenous vein graft using a transit time ultrasonic flow probe. Heart rate, blood pressure, and central venous pressure were documented at these time points. Administration of fenoldopam, 0.1 microg\\/kg\\/min, did not alter heart rate or blood pressure. A small, nonsignificant increase in LIMA blood flow occurred during the 15-minute study period (30 +\\/- 12 to 35 +\\/- 10 mL\\/min) in patients who received fenoldopam. No significant changes occurred in the placebo group. CONCLUSIONS: The findings indicate that fenoldopam, 0.1 microg\\/kg\\/min, did not influence coronary conduit blood flow to a clinically significant extent. The small increase in LIMA blood flow may be of greater importance in high-risk patients or in the prevention of coronary arterial spasm.

  15. A simple model of cerebral blood flow dependence on arterial blood pressure

    CERN Document Server

    Gersten, Alexander

    2011-01-01

    It is shown that the dependence of the cerebral blood flow (CBF) on mean arterial blood pressure (MABP) can be described with a simple model having the following assumptions. Below certain MABP (denoted as MABP1) there are no autoregulatory or feedback mechanisms influencing CBF. Between MABP1 and MABP2 (MABP at which breakthrough accurs) there is a linear (on MABP) dependent feedback with a sloap depending very much on the individual considered. The classical autoregulation model with a plateau in between MABP1 and MABP2 is a particular case of this model. The model describes well the experiments performed on dogs (Harper 1966), for which the individual feedback sloap parameter varied to great extent, indicating the importance of mesurments on individuals against averaged mesurments (or measurments on diffent individuals) which superficially support the classical autoregulation. New effect of decreased CBF, while increasing MABP, was observed.

  16. Regulation of exercise blood flow: Role of free radicals.

    Science.gov (United States)

    Trinity, Joel D; Broxterman, Ryan M; Richardson, Russell S

    2016-09-01

    During exercise, oxygen and nutrient rich blood must be delivered to the active skeletal muscle, heart, skin, and brain through the complex and highly regulated integration of central and peripheral hemodynamic factors. Indeed, even minor alterations in blood flow to these organs have profound consequences on exercise capacity by modifying the development of fatigue. Therefore, the fine-tuning of blood flow is critical for optimal physical performance. At the level of the peripheral circulation, blood flow is regulated by a balance between the mechanisms responsible for vasodilation and vasoconstriction. Once thought of as toxic by-products of in vivo chemistry, free radicals are now recognized as important signaling molecules that exert potent vasoactive responses that are dependent upon the underlying balance between oxidation-reduction reactions or redox balance. Under normal healthy conditions with low levels of oxidative stress, free radicals promote vasodilation, which is attenuated with exogenous antioxidant administration. Conversely, with advancing age and disease where background oxidative stress is elevated, an exercise-induced increase in free radicals can further shift the redox balance to a pro-oxidant state, impairing vasodilation and attenuating blood flow. Under these conditions, exogenous antioxidants improve vasodilatory capacity and augment blood flow by restoring an "optimal" redox balance. Interestingly, while the active skeletal muscle, heart, skin, and brain all have unique functions during exercise, the mechanisms by which free radicals contribute to the regulation of blood flow is remarkably preserved across each of these varied target organs. PMID:26876648

  17. Regulation of exercise blood flow: Role of free radicals.

    Science.gov (United States)

    Trinity, Joel D; Broxterman, Ryan M; Richardson, Russell S

    2016-09-01

    During exercise, oxygen and nutrient rich blood must be delivered to the active skeletal muscle, heart, skin, and brain through the complex and highly regulated integration of central and peripheral hemodynamic factors. Indeed, even minor alterations in blood flow to these organs have profound consequences on exercise capacity by modifying the development of fatigue. Therefore, the fine-tuning of blood flow is critical for optimal physical performance. At the level of the peripheral circulation, blood flow is regulated by a balance between the mechanisms responsible for vasodilation and vasoconstriction. Once thought of as toxic by-products of in vivo chemistry, free radicals are now recognized as important signaling molecules that exert potent vasoactive responses that are dependent upon the underlying balance between oxidation-reduction reactions or redox balance. Under normal healthy conditions with low levels of oxidative stress, free radicals promote vasodilation, which is attenuated with exogenous antioxidant administration. Conversely, with advancing age and disease where background oxidative stress is elevated, an exercise-induced increase in free radicals can further shift the redox balance to a pro-oxidant state, impairing vasodilation and attenuating blood flow. Under these conditions, exogenous antioxidants improve vasodilatory capacity and augment blood flow by restoring an "optimal" redox balance. Interestingly, while the active skeletal muscle, heart, skin, and brain all have unique functions during exercise, the mechanisms by which free radicals contribute to the regulation of blood flow is remarkably preserved across each of these varied target organs.

  18. The effect of 0.5% ropivacaine on epidural blood flow

    DEFF Research Database (Denmark)

    Dahl, J B; Simonsen, L; Mogensen, T;

    1990-01-01

    Twenty patients scheduled for elective abdominal surgery received epidural analgesia with 20 ml 0.5% ropivacaine or 0.5% bupivacaine. Epidural blood flow was measured by an epidural 133Xe clearance technique on the day before surgery (no local anaesthetic) and again 1 h before surgery, 30 min after...... injection of the local anaesthetic during continuous infusion (8 ml/h). Median initial blood flow was 5.0 ml/min and 6.0 ml/min per 100 g tissue in patients receiving ropivacaine and bupivacaine, respectively. After epidural bupivacaine, blood flow increased in 8 of 10 patients to 6.9 ml/min per 100 g...

  19. Surface flow measurements from drones

    Science.gov (United States)

    Tauro, Flavia; Porfiri, Maurizio; Grimaldi, Salvatore

    2016-09-01

    Drones are transforming the way we sense and interact with the environment. However, despite their increased capabilities, the use of drones in geophysical sciences usually focuses on image acquisition for generating high-resolution maps. Motivated by the increasing demand for innovative and high performance geophysical observational methodologies, we posit the integration of drone technology and optical sensing toward a quantitative characterization of surface flow phenomena. We demonstrate that a recreational drone can be used to yield accurate surface flow maps of sub-meter water bodies. Specifically, drone's vibrations do not hinder surface flow observations, and velocity measurements are in agreement with traditional techniques. This first instance of quantitative water flow sensing from a flying drone paves the way to novel observations of the environment.

  20. Effect of lying behavior on uterine blood flow in cows during the third trimester of gestation.

    Science.gov (United States)

    Nishida, T; Hosoda, K; Matsuyama, H; Ishida, M

    2004-08-01

    Seven Holstein cows (BW = 639.4 +/- 28.8 kg, age = 62.6 +/- 6.9 mo, parity = 3.1 +/- 0.4 yr) (mean +/- SE) were used to measure uterine blood flow using a transit time ultrasonic flow meter. Ultrasonic flow probes were implanted (d 218 +/- 4 of gestation) around both uterine arteries (n = 3) or the gravid uterine artery (n = 4) to measure variations in uterine blood flow through this vessel in response to postural change (standing and lying). Implantation of the ultrasonic blood flow probe was successful in all 7 cows. Uterine blood flow was measured for 22.9, 23.1, and 21.4 h/d on d 226, 248, and 269 of gestation, respectively. Cows exhibited normal durations of gestation (272.8 +/- 1.6 d), gave birth to normal healthy calves (birth weight = 41.5 +/- 3.0 kg), and did not retain their placenta. Uterine blood flow to the gravid horn during lying was greater than during standing on d 226 (standing vs. lying, 8.04 vs. 8.79 L/min, respectively), d 248 (9.87 vs. 11.06 L/min), and d 269 (8.15 vs. 9.74 L/min) of gestation. Cows spent nearly 50% of their time lying during our observations at all gestational ages. Greater blood supply to the gravid uterus was observed during lying than during standing in this study. PMID:15328259

  1. Coronary blood flow in the anesthetized American alligator (Alligator mississippiensis).

    Science.gov (United States)

    Jensen, Bjarke; Elfwing, Magnus; Elsey, Ruth M; Wang, Tobias; Crossley, Dane A

    2016-01-01

    Coronary circulation of the heart evolved early within ectothermic vertebrates and became of vital importance to cardiac performance in some teleost fish, mammals and birds. In contrast, the role and function of the coronary circulation in ectothermic reptiles remains largely unknown. Here, we investigated the systemic and coronary arterial responses of five anesthetized juvenile American alligators (Alligator mississippiensis) to hypoxia, acetylcholine, adenosine, sodium nitroprusside, isoproterenol, and phenylephrine. We recorded electrocardiograms, monitored systemic blood pressure, blood flows in both aortae, and blood flow in a major coronary artery supplying most of the right ventricle. Coronary arterial blood flow was generally forward, but there was a brief retrograde flow during a ventricular contraction. Blood pressure was significantly changed in all conditions. Acetylcholine decreased coronary forward flow, but this response was confounded by the concomitant lowered work of the ventricles due to decreased heart rate and blood pressure. Coronary forward flow was poorly correlated with heart rate and mean arterial pressure across treatments. Overall changes in coronary forward flow, significant and not significant, were generally in the same direction as mean arterial pressure and ventricular power, approximated as the product of systemic cardiac output and mean arterial pressure. PMID:26436857

  2. Non-Invasive Optical Blood Glucose Measurement

    Directory of Open Access Journals (Sweden)

    Megha C.Pande

    2013-07-01

    Full Text Available The method for noninvasively blood glucose monitoring system is discussed in this paper. Lot of research work has been done in developing the device which is completely noninvasive to avoid the pros & cons because of frequent pricking. In this paper we are trying to analyze the noninvasive blood glucose measurement study in the near infrared region which is the most suitable region for blood glucose measurement. For this purpose we use a technique which is similar to pulseoximetry based on near infrared spectrometry .An infrared light of particular wavelength is passed through fingertip containing an arterial pulse component are derived,thus minimizing influences of basal components such as resting blood volume,skin, muscle and bone.

  3. Blood flow and oxygenation in peritendinous tissue and calf muscle during dynamic exercise in humans

    DEFF Research Database (Denmark)

    Boushel, Robert Christopher; Langberg, H; Green, Sara Marie Ehrenreich;

    2000-01-01

    1. Circulation around tendons may act as a shunt for muscle during exercise. The perfusion and oxygenation of Achilles' peritendinous tissue was measured in parallel with that of calf muscle during exercise to determine (1) whether blood flow is restricted in peritendinous tissue during exercise...... with a rise in leg vascular conductance and microvascular haemoglobin volume, despite elevated systemic vascular resistance. 4. The parallel rise in calf muscle and peritendinous blood flow and fall in O2 saturation during exercise indicate that blood flow is coupled to oxidative metabolism in both tissue...... by dye dilution, arterial pressure by an arterial catheter-transducer, and muscle and peritendinous O2 saturation by spatially resolved spectroscopy (SRS). 3. Calf blood flow rose 20-fold with exercise, reaching 44 +/- 7 ml (100 g)-1 min-1 (mean +/- s.e.m. ) at 9 W, while Achilles' peritendinous flow...

  4. SELF-MIXING LASER-DOPPLER VELOCIMETRY OF LIQUID FLOW AND OF BLOOD PERFUSION IN TISSUE

    NARCIS (Netherlands)

    DEMUL, FFM; KOELINK, MH; WEIJERS, AL; GREVE, J; AARNOUDSE, JG; GRAAFF, R; DASSEL, ACM

    1992-01-01

    The velocimetry method of self-mixing, i.e., the feedback of Doppler-scattered light into the laser cavity, is used for the measurement of liquid flow and of blood perfusion in human tissue. The method is eIucidated by the registration of the blood perfusion of a finger under repeated occlusion of t

  5. Blood Glucose Measurement Using Bioimpedance Technique

    OpenAIRE

    Kamat, D. K.; Dhanashri Bagul; Patil, P. M.

    2014-01-01

    Bioimpedance measurement is gaining importance in wide field of bioresearch and biomedical systems due to its noninvasive nature. Noninvasive measurement method is very important to decrease infection and physical injuries which result due to invasive measurement. This paper presents basic principle of bioimpedance along with its application for blood glucose analysis and effect of frequency on impedance measurement. Input from bioimpedance sensor is given to amplifier and signal conditioner ...

  6. Aging, regional cerebral blood flow, and neuropsychological functioning

    International Nuclear Information System (INIS)

    Previous studies found changes in regional cerebral blood flow (rCBF) patterns related to both age and various cognitive tasks. However, no study has yet demonstrated a relationship between rCBF and performance on the Luria-Nebraska Neuropsychological Battery (LNNB) in an elderly group. Seventy-nine elderly volunteers (56-88 years old), both healthy and demented, underwent the 133xenon inhalation rCBF procedure and were given the LNNB. The decrements in the gray-matter blood flow paralleled decrements in performance on the LNNB. Using partial correlations, a significant proportion of shared variance was observed between gray-matter blood flow and the LNNB scales. However, there was much less of a relationship between white-matter blood flow and performance on the LNNB. This study suggests that even within a restricted age sample rCBF is related in a global way to neuropsychological functioning

  7. Aging, regional cerebral blood flow, and neuropsychological functioning

    Energy Technology Data Exchange (ETDEWEB)

    MacInnes, W.D.; Golden, C.J.; Gillen, R.W.; Sawicki, R.F.; Quaife, M.; Uhl, H.S.; Greenhouse, A.J.

    1984-10-01

    Previous studies found changes in regional cerebral blood flow (rCBF) patterns related to both age and various cognitive tasks. However, no study has yet demonstrated a relationship between rCBF and performance on the Luria-Nebraska Neuropsychological Battery (LNNB) in an elderly group. Seventy-nine elderly volunteers (56-88 years old), both healthy and demented, underwent the /sup 133/xenon inhalation rCBF procedure and were given the LNNB. The decrements in the gray-matter blood flow paralleled decrements in performance on the LNNB. Using partial correlations, a significant proportion of shared variance was observed between gray-matter blood flow and the LNNB scales. However, there was much less of a relationship between white-matter blood flow and performance on the LNNB. This study suggests that even within a restricted age sample rCBF is related in a global way to neuropsychological functioning.

  8. Skeletal Blood Flow in Bone Repair and Maintenance

    Institute of Scientific and Technical Information of China (English)

    Ryan E.Tomlinson; Matthew J.Silva

    2013-01-01

    Bone is a highly vascularized tissue, although this aspect of bone is often overlooked. In this article, the importance of blood flow in bone repair and regeneration will be reviewed. First, the skeletal vascular anato-my, with an emphasis on long bones, the distinct mechanisms for vascularizing bone tissue, and methods for remodeling existing vasculature are discussed. Next, techniques for quantifying bone blood flow are briefly summarized. Finally, the body of experimental work that demonstrates the role of bone blood flow in fracture healing, distraction osteogenesis, osteoporosis, disuse osteopenia, and bone grafting is examined. These results illustrate that adequate bone blood flow is an important clinical consideration, particularly during bone regeneration and in at-risk patient groups.

  9. Reduced blood flow to contracting skeletal muscle in ageing humans

    DEFF Research Database (Denmark)

    Nyberg, Michael Permin; Hellsten, Ylva

    2016-01-01

    consequences of ageing and physical inactivity can be challenging; yet, observations from cross-sectional and longitudinal studies on the effects of physical activity have provided some insight. Physical activity has the potential to offset the age-related decline in blood flow to contracting skeletal muscle...... during exercise where systemic blood flow is not limited by cardiac output, thereby improving O2 delivery and allowing for an enhanced energy production from oxidative metabolism. The mechanisms underlying the increase in blood flow with regular physical activity include improved endothelial function...... the O2 demand of the active skeletal muscle of aged individuals during conditions where systemic blood flow is not limited by cardiac output seems to a large extent to be related to the level of physical activity. This article is protected by copyright. All rights reserved....

  10. Ultrasonic measurement of liquid flow

    International Nuclear Information System (INIS)

    The measurement of flow speeds and levels of filling in pipelines and vessels requires a process of measurement to which the medium inside the pipe or the vessel is accessible. This problem can be solved by ultrasonics: Ultrasonics can 'penetrate' solids and liquids and therefore give access to the medium from outside. In this article, a survey is given in the first part on various techniques for measuring the speed of flow of liquids. The physical principles are introduced and the boundary conditions are discussed. In the second part, a practical example of measuring the level of filling in vessels and pipelines from outside at temperatures up to 300 C is given. (orig./HM)

  11. Blood flow changes coincide with cellular rearrangements during blood vessel pruning in zebrafish embryos.

    Directory of Open Access Journals (Sweden)

    Eva Kochhan

    Full Text Available After the initial formation of a highly branched vascular plexus, blood vessel pruning generates a hierarchically structured network with improved flow characteristics. We report here on the cellular events that occur during the pruning of a defined blood vessel in the eye of developing zebrafish embryos. Time-lapse imaging reveals that the connection of a new blood vessel sprout with a previously perfused multicellular endothelial tube leads to the formation of a branched, Y-shaped structure. Subsequently, endothelial cells in parts of the previously perfused branch rearrange from a multicellular into a unicellular tube, followed by blood vessel detachment. This process is accompanied by endothelial cell death. Finally, we show that differences in blood flow between neighboring vessels are important for the completion of the pruning process. Our data suggest that flow induced changes in tubular architecture ensure proper blood vessel pruning.

  12. Middle cerebral artery blood velocity and cerebral blood flow and O2 uptake during dynamic exercise

    DEFF Research Database (Denmark)

    Madsen, P L; Sperling, B K; Warming, T;

    1993-01-01

    Results obtained by the 133Xe clearance method with external detectors and by transcranial Doppler sonography (TCD) suggest that dynamic exercise causes an increase of global average cerebral blood flow (CBF). These data are contradicted by earlier data obtained during less-well-defined conditions....... To investigate this controversy, we applied the Kety-Schmidt technique to measure the global average levels of CBF and cerebral metabolic rate of oxygen (CMRO2) during rest and dynamic exercise. Simultaneously with the determination of CBF and CMRO2, we used TCD to determine mean maximal flow velocity...... in the middle cerebral artery (MCA Vmean). For values of CBF and MCA Vmean a correction for an observed small drop in arterial PCO2 was carried out. Baseline values for global CBF and CMRO2 were 50.7 and 3.63 ml.100 g-1.min-1, respectively. The same values were found during dynamic exercise, whereas a 22% (P

  13. Experimental comparison of mammalian and avian blood flow in microchannels

    Science.gov (United States)

    Fink, Kathryn; Liepmann, Dorian

    2015-11-01

    The non-Newtonian, shear rate dependent behavior of blood in microchannel fluid dynamics has been studied for nearly a century, with a significant focus on the characteristics of human blood. However, for over 200 years biologists have noted significant differences in red blood cell characteristics across vertebrate species, with particularly drastic differences in cell size and shape between mammals and non-mammalian classes. We present an experimental analysis of flow in long microchannels for several varieties of mammalian and avian blood, across a range of hematocrits, channel diameters, and flow rates. Correlation of shear rate and viscosity is compared to existing constitutive equations for human blood to further quantify the importance of red blood cell characteristics. Ongoing experimental results are made available in an online database for reference or collaboration. K.F. acknowledges funding from the ARCS Foundation and an NSF Graduate Research Fellowship through NSF Grant DGE 1106400.

  14. Evaluation of cutaneous blood flow responses by 133Xe washout and a laser-Doppler flowmeter

    International Nuclear Information System (INIS)

    A new method for noninvasive measurement of cutaneous blood flow is laser-Doppler flowmetry. The technique is based on the fact that laser light is back-scattered from the moving red blood cells, with Doppler-shifted frequencies; these impulses lead to photodetectors and are converted to flow signals. In this work we used a new system with a low noise level. Comparison was made between this technique and the atraumatic epicutaneous 133Xe technique for measurement of cutaneous blood flow during reactive hyperemia and orthostatic pressure changes. The laser-Doppler flowmeter seems to measure blood flow in capillaries as well as in arteriovenous anastomoses, while the 133Xe method probably measures only capillary flow. A calibration of the laser-Doppler method against the 133Xe method would appear to be impossible in skin areas where arteriovenous anastomoses are present. The changes in blood flow during reactive hyperemia, orthostatic pressure changes, and venous stasis were found to be parallel as measured by the two methods in skin areas without shunt vessels. The laser-Doppler flowmeter would appear to be a useful supplement to the 133Xe washout method in cutaneous vascular physiology, but it is important to keep in mind that different parameters may be measured

  15. Laser Doppler flowmetry: reproducibility, reliability, and diurnal blood flow variations.

    Science.gov (United States)

    Roeykens, Herman J J; Deschepper, Ellen; De Moor, Roeland J G

    2016-08-01

    The aim of this investigation was (1) to evaluate the reliability of laser Doppler flowmetry (LDF) taking into consideration the use of a silicone splint and the inclination of the probe towards the buccal surface of a human tooth and (2) to determine whether diurnal variations of pulpal blood flow can be registered by means of LDF. Forty-one splints were made by one and the same principal investigator for the registration of pulpal blood flow in vivo in a maxillary right central incisor. Thirty dentists, without experience in LDF recording, were then asked to drill a right-angled shaft in a pre-manufactured splint with a referral point at 2 mm from the enamel-cement border central on the buccal surface of the right central upper incisor. The remaining 11 splints were handled by the principal investigator. The shafts in the 30 splints were analysed using Cone Beam CT imaging of the axial and sagittal angles and compared these to the 11 shafts prepared by the trained principal investigator. LDF was recorded for 90 s in each splint and statistically analysed. LDF values without the use of a splint were statistically significantly different (p < 0.05) and the variance was greater, indicating the superiority of splint use. Significant diurnal variations on LDF values were observed, indicating that special attention should be paid to registration during the day, especially when multiple measurements are to be compared. PMID:27184153

  16. Radiohalogenated thienylethylamine derivatives for evaluating local cerebral blood flow

    Science.gov (United States)

    Goodman, Mark M.; Knapp, Jr., Furn F.

    1990-01-01

    Radiopharmaceuticals useful in brain imaging comprising radiohalogenated thienylethylamine derivatives. The compounds are 5-halo-thiophene-2-isopropyl amines able to cross the blood-brain barrier and be retained for a sufficient length of time to allow the evaluation or regional blood flow by radioimaging of the brain.

  17. SPECT with [99mTc]-d,l-hexamethyl-propylene amine oxime (HM-PAO) compared with regional cerebral blood flow measured by PET

    DEFF Research Database (Denmark)

    Yonekura, Y; Nishizawa, S; Mukai, Thomas Søgaard;

    1988-01-01

    (PET) using the oxygen-15 CO2 inhalation technique. Although HM-PAO SPECT and rCBF PET images showed a similar distribution pattern the HM-PAO SPECT image showed less contrast between high and low activity flow regions than the rCBF image and a nonlinear relationship between HM-PAO activity and r...

  18. Increased blood flow prevents intramucosal acidosis in sheep endotoxemia: a controlled study

    OpenAIRE

    Dubin, Arnaldo; Murias, Gastón; Maskin, Bernardo; Pozo, Mario O; Sottile, Juan P; Barán, Marcelo; Edul, Vanina S Kanoore; Canales, Héctor S; Badie, Julio C; Etcheverry, Graciela; Estenssoro, Elisa

    2005-01-01

    Introduction Increased intramucosal–arterial carbon dioxide tension (PCO2) difference (ΔPCO2) is common in experimental endotoxemia. However, its meaning remains controversial because it has been ascribed to hypoperfusion of intestinal villi or to cytopathic hypoxia. Our hypothesis was that increased blood flow could prevent the increase in ΔPCO2. Methods In 19 anesthetized and mechanically ventilated sheep, we measured cardiac output, superior mesenteric blood flow, lactate, gases, hemoglobi...

  19. Blood flow structure in patients with coronary heart disease

    Science.gov (United States)

    Malinova, Lidia I.; Simonenko, Georgy V.; Denisova, Tatyana P.; Tuchin, Valery V.

    2007-05-01

    Blood flow structure was studied by PC integrated video camera with following slide by slide analysis. Volumetric blood flow velocity was supporting on constant level (1 ml/h). Silicone tube of diameter comparable with coronary arteries diameter was used as vessel model. Cell-cell interactions were studied under glucose and anticoagulants influence. Increased adhesiveness of blood cells to tube walls was revealed in patient with coronary heart disease (CHD) compare to practically healthy persons (PHP). In patients with stable angina pectoris of high functional class and patients with AMI shear stress resistant erythrocyte aggregates were predominating in blood flow structure up to microclots formation. Clotting and erythrocytes aggregation increase as response to glucose solution injection, sharply defined in patients with CHD. Heparin injection (10 000 ED) increased linear blood flow velocity both in patients with CHD and PHP. After compare our results with other author's data we can consider that method used in our study is sensible enough to investigate blood flow structure violations in patients with CHD and PHP. Several differences of cell-cell interaction in flow under glucose and anticoagulant influence were found out in patients with CHD and PHP.

  20. Pancreatic islet blood flow in conscious rats during hyperglycemia and hypoglycemia.

    Science.gov (United States)

    Iwase, M; Tashiro, K; Uchizono, Y; Goto, D; Yoshinari, M

    2001-06-01

    Anesthesia affects general hemodynamics and regulation of organ perfusion. We used colored microspheres to measure pancreatic islet blood flow in conscious rats at two time points, during either hyperglycemia or hypoglycemia. This method, using black and green microspheres, was validated by comparison with previous microsphere experiments and by lack of effect of a nonmetabolizable glucose analog, 3-O-methylglucose, on islet perfusion. Basal and glucose-stimulated islet blood flow levels were similar in pentobarbital sodium-anesthetized and conscious rats. However, the basal distribution of pancreatic blood flow was altered by anesthesia (fractional islet blood flow 5.8 +/- 0.4% in conscious rats, 7.9 +/- 0.8% in pentobarbital-anesthetized rats, P conscious rats, whereas islet blood flow remained unchanged and fractional islet blood flow was decreased (5.8 +/- 0.5% in the basal state, 4.2 +/- 0.4% during hypoglycemia, P < 0.001). Methylatropine pretreatment significantly increased islet blood flow during hypoglycemia by 181%. This result suggests that prevention of hypoglycemia-induced increase in islet perfusion may be mediated, at least in part, by a cholinergic, vagal muscarinic mechanism. PMID:11353660

  1. Laser Doppler microscopy of blood flows in fish embryos at different stages of ontogenesis

    Science.gov (United States)

    Savchenko, Natalia B.; Priezzhev, Alexander V.; Levenko, Borislav A.

    1995-02-01

    Laser Doppler microscopy is an efficient method of in vivo measurements of flow velocities in different biological objects. It is based on the registration of frequency shifts in light quasielastically scattered from particles moving in the flows. To study the embryonic development of the cardiac-vascular system in embryos of warm water fishes, embryos of Macropodus opercularis have been used. Doppler spectra from pulsatile blood flows in selected vessels and their changes in the process of ontogenesis have been registered. The recording of the successive spectra and their computer processing yield the varying dynamics of blood flows. Typical age dependencies of velocity patterns in the embryos are presented.

  2. Ultrafast Ultrasound Imaging of Ocular Anatomy and Blood Flow

    Science.gov (United States)

    Urs, Raksha; Ketterling, Jeffrey A.; Silverman, Ronald H.

    2016-01-01

    Purpose Ophthalmic ultrasound imaging is currently performed with mechanically scanned single-element probes. These probes have limited capabilities overall and lack the ability to image blood flow. Linear-array systems are able to detect blood flow, but these systems exceed ophthalmic acoustic intensity safety guidelines. Our aim was to implement and evaluate a new linear-array–based technology, compound coherent plane-wave ultrasound, which offers ultrafast imaging and depiction of blood flow at safe acoustic intensity levels. Methods We compared acoustic intensity generated by a 128-element, 18-MHz linear array operated in conventionally focused and plane-wave modes and characterized signal-to-noise ratio (SNR) and lateral resolution. We developed plane-wave B-mode, real-time color-flow, and high-resolution depiction of slow flow in postprocessed data collected continuously at a rate of 20,000 frames/s. We acquired in vivo images of the posterior pole of the eye by compounding plane-wave images acquired over ±10° and produced images depicting orbital and choroidal blood flow. Results With the array operated conventionally, Doppler modes exceeded Food and Drug Administration safety guidelines, but plane-wave modalities were well within guidelines. Plane-wave data allowed generation of high-quality compound B-mode images, with SNR increasing with the number of compounded frames. Real-time color-flow Doppler readily visualized orbital blood flow. Postprocessing of continuously acquired data blocks of 1.6-second duration allowed high-resolution depiction of orbital and choroidal flow over the cardiac cycle. Conclusions Newly developed high-frequency linear arrays in combination with plane-wave techniques present opportunities for the evaluation of ocular anatomy and blood flow, as well as visualization and analysis of other transient phenomena such as vessel wall motion over the cardiac cycle and saccade-induced vitreous motion. PMID:27428169

  3. Laser speckle contrast imaging for monitoring changes in microvascular blood flow

    DEFF Research Database (Denmark)

    Ambrus, Rikard; Strandby, Rune B.; Svendsen, Lars Bo;

    2016-01-01

    the reproducibility of the LSCI technique when assessing the intra-abdominal microcirculation of the pig. METHODS: During trial 1, a fish gill arch was mechanically perfused with heparinized fish blood under controlled stepwise-altered flow rates alongside mechanically induced movement artefacts. The microcirculation......BACKGROUND/AIMS: Microvascular blood flow is essential for healing and predicts surgical outcome. The aim of the current study was to investigate the relation between fluxes measured with the laser speckle contrast imaging (LSCI) technique and changes in absolute blood flow. In addition, we studied...... of the fish gill was simultaneously assessed with the LSCI technique. In trial 2, microcirculation was measured in the stomach, liver, and small intestine of 10 pigs by two observers. RESULTS: A linear correlation was observed between flux and volumetric flow. During conditions of no volumetric flow, the high...

  4. Mechanisms of recovery from aphasia: evidence from serial xenon 133 cerebral blood flow studies

    International Nuclear Information System (INIS)

    In 21 patients who suffered aphasia resulting from left hemisphere ischemic infarction, the xenon 133 inhalation cerebral blood flow technique was used to measure cerebral blood flow within 3 months and 5 to 12 months after stroke. In addition to baseline measurements, cerebral blood flow measurements were also carried out while the patients were performing purposeful listening. In patients with incomplete recovery of comprehension and left posterior temporal-inferior parietal lesions, greater cerebral blood flow occurred with listening in the right inferior frontal region in the late studies than in the early studies. In patients with nearly complete recovery of comprehension and without left posterior temporal-inferior parietal lesions, early listening studies showed diffuse right hemisphere increases in cerebral blood flow. Later listening studies in this latter patient group showed greater cerebral blood flow in the left posterior temporal-inferior parietal region. The study provides evidence for participation of the right hemisphere in language comprehension in recovering aphasics, and for later return of function in left hemisphere regions that may have been functionally impaired early during recovery

  5. Ultrasonic Imaging of Hemodynamic Force in Carotid Blood Flow

    Science.gov (United States)

    Nitta, N.; Homma, K.

    Hemodynamic forces including blood pressure and shear stress affect vulnerable plaque rupture in arteriosclerosis and biochemical activation of endothelium such as NO production. In this study, a method for estimating and imaging shear stress and pressure gradient distributions in blood vessel as the hemodynamic force based on viscosity estimation is presented. Feasibility of this method was investigated by applying to human carotid blood flow. Estimated results of shear stress and pressure gradient distributions coincide with the ideal distributions obtained by numerical simulation and flow-phantom experiment.

  6. CHARACTERIZATION OF RENAL BLOOD FLOW REGULATION BASED ON WAVELET COEFFICIENTS

    DEFF Research Database (Denmark)

    Pavlov, A.N.; Pavlova, O.N.; Mosekilde, Erik;

    2010-01-01

    The purpose of this study is to demonstrate the possibility of revealing new characteristic features of renal blood flow autoregulation in healthy and pathological states through the application of discrete wavelet transforms to experimental time series for normotensive and hypertensive rats....... A reduction in the variability of the wavelet coefficients in hypertension is observed at both the microscopic level of the blood flow in efferent arterioles of individual nephrons and at the macroscopic level of the blood pressure in the main arteries. The reduction is manifest in both of the main frequency...

  7. Research Advances: DRPS--Let The Blood Flow!

    Science.gov (United States)

    King, Angela G.

    2007-01-01

    A team from the University of Pittsburgh's McGowan Institute for Regenerative Medicine has shown the potential for clinical use of the drag-reducing polymer (DRP) poly(N-vinylformamide), or PNVF. The high molecular weight PNVF is shown to reduce resistance to turbulent flow in a pipe and to enhance blood flow in animal models and it also…

  8. Blood Flow through an Open-Celled Foam

    Science.gov (United States)

    Ortega, Jason; Maitland, Duncan

    2011-11-01

    The Hazen-Dupuit-Darcy (HDD) equation is commonly used in engineering applications to model the pressure gradient of flow through a porous media. One major advantage of this equation is that it simplifies the complex geometric details of the porous media into two coefficients: the permeability, K, and form factor, C. However through this simplification, the flow details within the porous media are no longer accessible, making it difficult to study the phenomena that contribute to changes in K and C due to clotting of blood flow. To obtain a more detailed understanding of blood flow through a porous media, a direct assessment of the complex interstitial geometry and flow is required. In this study, we solve the Navier-Stokes equations for Newtonian and non-Newtonian blood flow through an open-celled foam geometry obtained from a micro-CT scan. The nominal strut size of the foam sample is of O(10e-5) m and the corresponding Reynolds number based upon this length ranges up to O(10). Fitting the pressure gradient vs. Darcy velocity data with the HDD equation demonstrates that both viscous and inertial forces play an important role in the flow through the foam at these Reynolds numbers. Recirculation zones are observed to form in the wake of the pore struts, producing regions of flow characterized by both low shear rates and long fluid residence times, factors of which have been shown in previous studies to promote blood clotting.

  9. A multiple disk centrifugal pump as a blood flow device.

    Science.gov (United States)

    Miller, G E; Etter, B D; Dorsi, J M

    1990-02-01

    A multiple disk, shear force, valveless centrifugal pump was studied to determine its suitability as a blood flow device. A pulsatile version of the Tesla viscous flow turbine was designed by modifying the original steady flow pump concept to produce physiological pressures and flows with the aid of controlling circuitry. Pressures and flows from this pump were compared to a Harvard Apparatus pulsatile piston pump. Both pumps were connected to an artificial circulatory system. Frequency and systolic duration were varied over a range of physiological conditions for both pumps. The results indicated that the Tesla pump, operating in a pulsatile mode, is capable of producing physiologic pressures and flows similar to the Harvard pump and other pulsatile blood pumps. PMID:2312140

  10. Determinants of resting cerebral blood flow in sickle cell disease.

    Science.gov (United States)

    Bush, Adam M; Borzage, Matthew T; Choi, Soyoung; Václavů, Lena; Tamrazi, Benita; Nederveen, Aart J; Coates, Thomas D; Wood, John C

    2016-09-01

    Stroke is common in children with sickle cell disease and results from an imbalance in oxygen supply and demand. Cerebral blood flow (CBF) is increased in patients with sickle cell disease to compensate for their anemia, but adequacy of their oxygen delivery has not been systematically demonstrated. This study examined the physiological determinants of CBF in 37 patients with sickle cell disease, 38 ethnicity matched control subjects and 16 patients with anemia of non-sickle origin. Cerebral blood flow was measured using phase contrast MRI of the carotid and vertebral arteries. CBF increased inversely to oxygen content (r(2)  = 0.69, P Brain oxygen delivery, the product of CBF and oxygen content, was normal in all groups. Brain composition, specifically the relative amounts of grey and white matter, was the next strongest CBF predictor, presumably by influencing cerebral metabolic rate. Grey matter/white matter ratio and CBF declined monotonically until the age of 25 in all subjects, consistent with known maturational changes in brain composition. Further CBF reductions were observed with age in subjects older than 35 years of age, likely reflecting microvascular aging. On multivariate regression, CBF was independent of disease state, hemoglobin S, hemoglobin F, reticulocyte count and cell free hemoglobin, suggesting that it is regulated similarly in patients and control subjects. In conclusion, sickle cell disease patients had sufficient oxygen delivery at rest, but accomplish this only by marked increases in their resting CBF, potentially limiting their ability to further augment flow in response to stress. Am. J. Hematol. 91:912-917, 2016. © 2016 Wiley Periodicals, Inc. PMID:27263497

  11. Pulsatile blood flow, shear force, energy dissipation and Murray's Law

    Directory of Open Access Journals (Sweden)

    Bengtsson Hans-Uno

    2006-08-01

    Full Text Available Abstract Background Murray's Law states that, when a parent blood vessel branches into daughter vessels, the cube of the radius of the parent vessel is equal to the sum of the cubes of the radii of daughter blood vessels. Murray derived this law by defining a cost function that is the sum of the energy cost of the blood in a vessel and the energy cost of pumping blood through the vessel. The cost is minimized when vessel radii are consistent with Murray's Law. This law has also been derived from the hypothesis that the shear force of moving blood on the inner walls of vessels is constant throughout the vascular system. However, this derivation, like Murray's earlier derivation, is based on the assumption of constant blood flow. Methods To determine the implications of the constant shear force hypothesis and to extend Murray's energy cost minimization to the pulsatile arterial system, a model of pulsatile flow in an elastic tube is analyzed. A new and exact solution for flow velocity, blood flow rate and shear force is derived. Results For medium and small arteries with pulsatile flow, Murray's energy minimization leads to Murray's Law. Furthermore, the hypothesis that the maximum shear force during the cycle of pulsatile flow is constant throughout the arterial system implies that Murray's Law is approximately true. The approximation is good for all but the largest vessels (aorta and its major branches of the arterial system. Conclusion A cellular mechanism that senses shear force at the inner wall of a blood vessel and triggers remodeling that increases the circumference of the wall when a shear force threshold is exceeded would result in the observed scaling of vessel radii described by Murray's Law.

  12. Quantifying Blood Flow in the DIEP Flap: An Ultrasonographic Study

    Directory of Open Access Journals (Sweden)

    Joseph Richard Dusseldorp, BCom, MBBS(Hons

    2014-10-01

    Conclusions: This study confirms that perforator size is a critical factor in optimizing blood flow in perforator-based free tissue transfer. Further research is required to understand the flow dynamics of perforator flaps based on multiple perforators. However, surgeons should be cognizant that a single large perforator may have substantially higher flow rates than multiple small perforators. Routine FVI calculation is recommended to ensure complete flap survival.

  13. Turbulence Measurements in Swirling Flows

    Directory of Open Access Journals (Sweden)

    V. M. Domkundwar

    1981-10-01

    Full Text Available Investigation have been conducted to find out the region of high turbulent intensities in a swirling jet passing through a divergent passage. A hot wire anemometer is used to measure the turbulence intensity using a four position method. It has been concluded that the jet spreads with increasing diffuser angle and the region of high turbulent intensity also spreads. The high turbulence intensity region lies around the recirculation zone and it decays rapidly along the main flow direction.

  14. Differences in displayed pump flow compared to measured flow under varying conditions during simulated cardiopulmonary bypass.

    LENUS (Irish Health Repository)

    Hargrove, M

    2008-07-01

    Errors in blood flow delivery due to shunting have been reported to reduce flow by, potentially, up to 40-83% during cardiopulmonary bypass. The standard roller-pump measures revolutions per minute and a calibration factor for different tubing sizes calculates and displays flow accordingly. We compared displayed roller-pump flow with ultrasonically measured flow to ascertain if measured flow correlated with the heart-lung pump flow reading. Comparison of flows was measured under varying conditions of pump run duration, temperature, viscosity, varying arterial\\/venous loops, occlusiveness, outlet pressure, use of silicone or polyvinyl chloride (PVC) in the roller race, different tubing diameters, and use of a venous vacuum-drainage device.

  15. Aerobic fitness is associated with greater hippocampal cerebral blood flow in children.

    Science.gov (United States)

    Chaddock-Heyman, Laura; Erickson, Kirk I; Chappell, Michael A; Johnson, Curtis L; Kienzler, Caitlin; Knecht, Anya; Drollette, Eric S; Raine, Lauren B; Scudder, Mark R; Kao, Shih-Chun; Hillman, Charles H; Kramer, Arthur F

    2016-08-01

    The present study is the first to investigate whether cerebral blood flow in the hippocampus relates to aerobic fitness in children. In particular, we used arterial spin labeling (ASL) perfusion MRI to provide a quantitative measure of blood flow in the hippocampus in 73 7- to 9-year-old preadolescent children. Indeed, aerobic fitness was found to relate to greater perfusion in the hippocampus, independent of age, sex, and hippocampal volume. Such results suggest improved microcirculation and cerebral vasculature in preadolescent children with higher levels of aerobic fitness. Further, aerobic fitness may influence how the brain regulates its metabolic demands via blood flow in a region of the brain important for learning and memory. To add specificity to the relationship of fitness to the hippocampus, we demonstrate no significant association between aerobic fitness and cerebral blood flow in the brainstem. Our results reinforce the importance of aerobic fitness during a critical period of child development. PMID:27419884

  16. Normalization of thyroid blood flow in Graves' hyperthyroidism following radioactive iodine therapy

    Energy Technology Data Exchange (ETDEWEB)

    Chang, D.C.S.; Woodcock, J.P.; Shedden, E.J.; Lazarus, J.H.; Wheeler, M.H.; McGregor, A.M. (University Hospital of Wales, Cardiff (UK). Medical Physics Dept.)

    1990-05-01

    In a group of 12 patients with Graves' hyperthyroidism, administration of 514 {plus minus} 43 (mean {plus minus} SD) MBq iodine-131 was associated with a fall of superior thyroid artery (STA) blood flow in two at 6 months and in eight at 11 months. The reduction in time-averaged velocity at 11 months correlated with the reduction in FT4 and in FT3 at this time. In four patients who had persistent elevated STA blood flow, two were still hyperthyroid. The diameter of the STA was unchanged at 6 months and only half the patients had reduction of their STA size at 11 months after radioiodine (RAI) therapy. These data indicate that normalization of STA blood flow precedes normalization of STA size in patients treated with RAI. Further work is required to determine whether STA blood flow measurements are of predictive value in treatment outcome. (author).

  17. Intrinsic regulation of blood flow in adipose tissue

    DEFF Research Database (Denmark)

    Henriksen, O; Nielsen, Steen Levin; Paaske, W

    1976-01-01

    Previous studies on intact human subcutaneous tissue have shown, that blood flow remains constant during minor changes in perfusion pressure. This so-called autoregulatory response has not been demonstrable in isolated preparations of adipose tissue. In the present study on isolated, denervated...... vasoconstriction with pronounced flow reduction. These two reactions may be important for local regulation of blood flow in subcutaneous tissue during orthostatic changes in arterial and venous pressure. It is concluded that the response in adipose tissue to changes in arterial pressure (autoregulation), venous...... subcutaneous tissue in female rabbits only 2 of 12 expts. revealed an autoregulatory response during reduction in arterial perfusion pressure. Effluent blood flow from the tissue in the control state was 15.5 ml/100 g-min (S.D. 6.4, n = 12) corresponding to slight vasodilatation of the exposed tissue...

  18. Measuring skewness of red blood cell deformability distribution by laser ektacytometry

    Energy Technology Data Exchange (ETDEWEB)

    Nikitin, S Yu; Priezzhev, A V; Lugovtsov, A E [International Laser Center, M. V. Lomonosov Moscow State University, Moscow (Russian Federation); Ustinov, V D [M. V. Lomonosov Moscow State University, Faculty of Computational Mathematics and Cybernetics, Moscow (Russian Federation)

    2014-08-31

    An algorithm is proposed for measuring the parameters of red blood cell deformability distribution based on laser diffractometry of red blood cells in shear flow (ektacytometry). The algorithm is tested on specially prepared samples of rat blood. In these experiments we succeeded in measuring the mean deformability, deformability variance and skewness of red blood cell deformability distribution with errors of 10%, 15% and 35%, respectively. (laser biophotonics)

  19. Cyclic variations of high-frequency ultrasonic backscattering from blood under pulsatile flow.

    Science.gov (United States)

    Huang, Chih-Chung

    2009-08-01

    It was shown previously that ultrasonic scattering from whole blood varies during the flow cycle under pulsatile flow both in vitro and in vivo. It has been postulated that the cyclic variations of the backscattering signal are associated with red blood cell (RBC) aggregation in flowing whole blood. To obtain a better understanding of the relationship between blood backscattering and RBC aggregation behavior for pulsatile flowing blood, the present study used high-frequency ultrasound to characterize blood properties. The backscattering signals from both whole blood and an RBC suspension at different peak flow velocities (from 10 to 30 cm/s) and hematocrits (20% and 40%) under pulsatile flow (stroke rate of 20 beats/min) were measured with 3 single-element transducers at frequencies of 10, 35, and 50 MHz in a mock flow loop. To avoid the frequency response problem of a Doppler flowmeter, the integrated backscatter (IB) and flow velocity as functions of time were calculated directly using RF signals from flowing blood. The experimental results showed that cyclic variations of the IB curve were clearly observed at a low flow velocity and a hematocrit of 40% when using 50 MHz ultrasound, and that these variations became weaker as the peak flow velocity increased. However, these cyclic variations were detected only at 10 cm/s when using 10 MHz ultrasound. These results demonstrate that a high flow velocity can stop the formation of rouleaux and that a high hematocrit can promote RBC aggregation to produce cyclic variations of the backscattering signal under pulsatile flow. In addition, slight cyclic variations of the IB curve for an RBC suspension were observed at 35 and 50 MHz. Furthermore, the peak of the IB curve from whole blood led the peak of the velocity waveform when using high-frequency ultrasound, which could be explained by the assumption that a rapid flow can promote RBC aggregation under pulsatile flow. Together, the experimental results showed that the

  20. Nonlinear interactions in renal blood flow regulation

    DEFF Research Database (Denmark)

    Marsh, Donald J.; Sosnovtseva, Olga; Chon, Ki H.;

    2005-01-01

    We have developed a model of tubuloglomerular feedback (TGF) and the myogenic mechanism in afferent arterioles to understand how the two mechanisms are coupled. This paper presents the model. The tubular model predicts pressure, flow, and NaCl concentration as functions of time and tubular length...

  1. Cerebral blood flow in normal and abnormal sleep and dreaming

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, J.S.; Ishikawa, Y.; Hata, T.; Karacan, I.

    1987-07-01

    Measurements of regional or local cerebral blood flow (CBF) by the xenon-133 inhalation method and stable xenon computerized tomography CBF (CTCBF) method were made during relaxed wakefulness and different stages of REM and non-REM sleep in normal age-matched volunteers, narcoleptics, and sleep apneics. In the awake state, CBF values were reduced in both narcoleptics and sleep apneics in the brainstem and cerebellar regions. During sleep onset, whether REM or stage I-II, CBF values were paradoxically increased in narcoleptics but decreased severely in sleep apneics, while in normal volunteers they became diffusely but more moderately decreased. In REM sleep and dreaming CBF values greatly increased, particularly in right temporo-parietal regions in subjects experiencing both visual and auditory dreaming.

  2. Cerebral blood flow in normal and abnormal sleep and dreaming

    International Nuclear Information System (INIS)

    Measurements of regional or local cerebral blood flow (CBF) by the xenon-133 inhalation method and stable xenon computerized tomography CBF (CTCBF) method were made during relaxed wakefulness and different stages of REM and non-REM sleep in normal age-matched volunteers, narcoleptics, and sleep apneics. In the awake state, CBF values were reduced in both narcoleptics and sleep apneics in the brainstem and cerebellar regions. During sleep onset, whether REM or stage I-II, CBF values were paradoxically increased in narcoleptics but decreased severely in sleep apneics, while in normal volunteers they became diffusely but more moderately decreased. In REM sleep and dreaming CBF values greatly increased, particularly in right temporo-parietal regions in subjects experiencing both visual and auditory dreaming

  3. Spatiotemporal changes in blood-brain barrier permeability, cerebral blood flow, T2 and diffusion following mild traumatic brain injury.

    Science.gov (United States)

    Li, Wei; Watts, Lora; Long, Justin; Zhou, Wei; Shen, Qiang; Jiang, Zhao; Li, Yunxia; Duong, Timothy Q

    2016-09-01

    The blood-brain barrier (BBB) can be impaired following traumatic brain injury (TBI), however the spatiotemporal dynamics of BBB leakage remain incompletely understood. In this study, we evaluated the spatiotemporal evolution of BBB permeability using dynamic contrast-enhanced MRI and measured the volume transfer coefficient (K(trans)), a quantitative measure of contrast agent leakage across the blood and extravascular compartment. Measurements were made in a controlled cortical impact (CCI) model of mild TBI in rats from 1h to 7 days following TBI. The results were compared with cerebral blood flow, T2 and diffusion MRI from the same animal. Spatially, K(trans) changes were localized to superficial cortical layers within a 1mm thickness, which was dramatically different from the changes in cerebral blood flow, T2 and diffusion, which were localized to not only the superficial layers but also to brain regions up to 2.2mm from the cortical surface. Temporally, K(trans) changes peaked at day 3, similar to CBF and ADC changes, but differed from T2 and FA, whose changes peaked on day 2. The pattern of superficial cortical layer localization of K(trans) was consistent with patterns revealed by Evans Blue extravasation. Collectively, these results suggest that BBB disruption, edema formation, blood flow disturbance and diffusion changes are related to different components of the mechanical impact, and may play different roles in determining injury progression and tissue fate processes following TBI. PMID:27208495

  4. Impact of extracorporeal blood flow rate on blood pressure, pulse rate and cardiac output during haemodialysis

    DEFF Research Database (Denmark)

    Schytz, Philip Andreas; Mace, Maria Lerche; Soja, Anne Merete Boas;

    2015-01-01

    BACKGROUND: If blood pressure (BP) falls during haemodialysis (HD) [intradialytic hypotension (IDH)] a common clinical practice is to reduce the extracorporeal blood flow rate (EBFR). Consequently the efficacy of the HD (Kt/V) is reduced. However, only very limited knowledge on the effect of redu...

  5. Disodium cromoglycate, a mast-cell stabilizer, alters postradiation regional cerebral blood flow in primates

    Energy Technology Data Exchange (ETDEWEB)

    Cockerham, L.G.; Doyle, T.F.; Pautler, E.L.; Hampton, J.D.

    1986-01-01

    Early transient incapacitation (ETI) is the complete cessation of performance during the first 30 min after radiation exposure, and performance decrement (PD) is a reduction in performance at the same time. Supralethal doses of radiation have been shown to produce a marked decrease in regional cerebral blood flow in primates concurrent with systemic hypotension and a dramatic release of mast-cell histamine. In an attempt to elucidate mechanisms underlying the radiation-induced ETI/PD phenomena and the postradiation decrease in cerebral blood flow, primates were given the mast-cell stabilizers disodium cromoglycate (DSCG) or BRL 22321 before exposure to 100 Gy whole-body gamma radiation. Hypothalamic and cortical blood flows were measured by hydrogen clearance, before and after radiation exposure. Systemic blood pressures were determined simultaneously. The data indicated that DSCG was successful in diminishing postradiation decrease in cerebral blood flow. Irradiated animals pretreated with DSCG, showed only a 10% decrease in hypothalamic blood flow 60 min postradiation, while untreated, irradiated animals showed a 57% decrease. The cortical blood flow of DSCG treated, irradiated animals showed a triphasic response, with a decrease of 38% at 10 min postradiation, then a rise to 1% below baseline at 20 min, followed by a fall to 42% below baseline by 50 min postradiation. In contrast, the untreated, irradiated animals showed a steady decrease in cortical blood flow to 79% below baseline by 50 min postradiation. There was no significant difference in blood-pressure response between the treated and untreated, irradiated animals. Systemic blood pressure showed a 60% decrease at 10 min postradiation, falling to a 71% decrease by 60 min.

  6. Peripheral blood flow control in diabetes mellitus

    DEFF Research Database (Denmark)

    Hilsted, Jannik

    1991-01-01

    Long term diabetes has a profound effect on the peripheral circulation. This has been demonstrated to be due to the presence of angiopathy and autonomic neuropathy, affecting autoregulation and distensibility of the vessels as well as local and central reflex regulation of the vascular resistance....... Whereas the hemodynamic consequences of vascular denervation are well known (causing blood pressure maladaptation to a number of stimuli such as standing, exercise and agonist infusion) (Hilsted 1985), the consequences of disturbances in autoregulation and distensibility remain to be established....

  7. Measurement in multiphase reacting flows

    Science.gov (United States)

    Chigier, N. A.

    1979-01-01

    A survey is presented of diagnostic techniques and measurements made in multiphase reacting flows. The special problems encountered by the presence of liquid droplets, soot and solid particles in high temperature chemically reacting turbulent environments are outlined. The principal measurement techniques that have been tested in spray flames are spark photography, laser anemometry, thermocouples and suction probes. Spark photography provides measurement of drop size, drop size distribution, drop velocity, and angle of flight. Photographs are analysed automatically by image analysers. Photographic techniques are reliable, inexpensive and proved. Laser anemometers have been developed for simultaneous measurement of velocity and size of individual particles in sprays under conditions of vaporization and combustion. Particle/gas velocity differentials, particle Reynolds numbers, local drag coefficients and direct measurement of vaporization rates can be made by laser anemometry. Gas temperature in sprays is determined by direct in situ measurement of time constants immediately prior to measurement with compensation and signal analysis by micro-processors. Gas concentration is measured by suction probes and gas phase chromatography. Measurements of particle size, particle velocity, gas temperature, and gas concentration made in airblast and pressure atomised liquid spray flames are presented.

  8. Effect of stratified inequality of blood flow on gas exchange in liquid-filled lungs.

    Science.gov (United States)

    West, J. B.; Maloney, J. E.; Castle, B. L.

    1972-01-01

    This investigation set out to answer two questions: (1) are the distal alveoli in the terminal lung units less well perfused than the proximal alveoli, i.e., is there stratification of blood flow; and (2) if so, does this enhance gas exchange in the presence of stratified inequality of ventilation. Excised dog lungs were ventilated with saline and perfused with blood. Following single inspirations of xenon 133 in saline and various periods of breath holding, the expired xenon concentration against volume was measured and it confirmed marked stratified inequality of ventilation under these conditions. By measuring the rate of depletion of xenon from alveoli during a period of blood flow, we showed that the alveoli which emptied at the end of expiration had 16% less blood flow than those exhaling earlier. However, by measuring the xenon concentration in pulmonary venous blood, we found that about 10% less tracer was transferred from the alveoli into the blood when the inspired xenon was stratified within the respiratory zone. Thus while stratification of blood flow was confirmed, it was shown to impair rather than enhance the efficiency of gas transfer.

  9. Blood Glucose Measurement Using Bioimpedance Technique

    Directory of Open Access Journals (Sweden)

    D. K. Kamat

    2014-01-01

    Full Text Available Bioimpedance measurement is gaining importance in wide field of bioresearch and biomedical systems due to its noninvasive nature. Noninvasive measurement method is very important to decrease infection and physical injuries which result due to invasive measurement. This paper presents basic principle of bioimpedance along with its application for blood glucose analysis and effect of frequency on impedance measurement. Input from bioimpedance sensor is given to amplifier and signal conditioner AD5933. AD5933 is then interfaced with microcontroller LPC1768 using I2C bus for displaying reading on LCD. Results can also be stored in database using UART interface of LPC1768.

  10. Design and Simulation of Axial Flow Maglev Blood Pump

    Directory of Open Access Journals (Sweden)

    Huachun Wu

    2011-03-01

    Full Text Available The axial flow maglev blood pump (AFMBP has become a global research focus and emphasis for artificial ventricular assist device, which has no mechanical contact, mechanical friction, compact structure and light weight, can effectively solve thrombus and hemolysis. Magnetic suspension and impeller is two of the important parts in the axial flow maglev blood pump, and their structure largely determines the blood pump performance. The research adopts electromagnetic and fluid finite element analysis, and puts forward a method to design the magnetic suspension and impeller of axial flow blood pump, which tacks into account the small volume of axial blood pump. The magnetic bearing’s characteristics are evaluated by electromagnetic finite element analysis. The Blades have been designed by calculating aerofoil bone line, and make simulation analysis for different thicken ways of blade by Fluent software, and make a conclusion that the blade thickened with certain rules has better characteristics in the same conditions. The results will provide some guidance for design of axial flow maglev blood pump, and establish theoretical basis for application of the implantable artificial heart pump.

  11. Diet-induced changes in subcutaneous adipose tissue blood flow in man

    DEFF Research Database (Denmark)

    Simonsen, L; Bülow, J; Astrup, A;

    1990-01-01

    The effect of a carbohydrate-rich meal on subcutaneous adipose tissue blood flow was studied with and without continuous i.v. infusion of propranolol in healthy volunteers. The subcutaneous adipose tissue blood flow was measured with the 133Xe washout method in three different locations...... it in the forearm. This indicates that the mechanism for the flow increase is elicited by a stimulation of vascular beta-adrenoceptors in the subcutaneous adipose tissue, since the beta-adrenoceptor inhibition did not affect the overall metabolic and hormonal responses to the meal.......: the forearm, the thigh and the abdomen. The subjects were given a meal consisting of white bread, jam, honey and apple juice (about 2300 kJ). The meal induced a twofold increase in blood flow in the examined tissues. Propranolol abolished the flow increase in the thigh and the abdomen and reduced...

  12. Effects of Aortic Irregularities on the Blood Flow

    Science.gov (United States)

    Gutmark-Little, Iris; Prahl-Wittberg, Lisa; van Wyk, Stevin; Mihaescu, Mihai; Fuchs, Laszlo; Backeljauw, Philippe; Gutmark, Ephraim

    2013-11-01

    Cardiovascular defects characterized by geometrical anomalies of the aorta and its effect on the blood flow are investigated. The flow characteristics change with the aorta geometry and the rheological properties of the blood. Flow characteristics such as wall shear stress often play an important role in the development of vascular disease. In the present study, blood is considered to be non-Newtonian and is modeled using the Quemada model, an empirical model that is valid for different red blood cell loading. Three patient-specific aortic geometries are studied using Large Eddy Simulations (LES). The three geometries represent malformations that are typical in patients populations having a genetic disorder called Turner syndrome. The results show a highly complex flow with regions of recirculation that are enhanced in two of the three aortas. Moreover, blood flow is diverted, due to the malformations, from the descending aorta to the three side branches of the arch. The geometry having an elongated transverse aorta has larger areas of strong oscillatory wall shear stress.

  13. Nocturnal foot blood flow in patients with arterial insufficiency

    DEFF Research Database (Denmark)

    Jelnes, Rolf; Tønnesen, K H

    1984-01-01

    Twenty-four hour continuous recording of xenon (133Xe) wash-out from the forefoot was performed on patients with normal circulations (n = 10) and on patients with different degrees of arterial insufficiency (n = 36). During day hours the calculated subcutaneous blood flow in the forefoot was on a...... claudication. In patients with severe ischaemia, i.e. having rest pain, the blood flow decreased by approximately 50%. The changes in local blood flow may be due to changes in local sympathetic tone and to changes in local perfusion pressure.......Twenty-four hour continuous recording of xenon (133Xe) wash-out from the forefoot was performed on patients with normal circulations (n = 10) and on patients with different degrees of arterial insufficiency (n = 36). During day hours the calculated subcutaneous blood flow in the forefoot...... was on average the same in patients with normal circulations and in patients with different degrees of arterial insufficiency (mean: 2.0 +/- 0.8 ml min-1 100 g-1). During sleep the blood flow nearly doubled in patients with normal circulations; no systematic change was seen in patients with intermittent...

  14. An analysis of the sluicing gate in pulmonary blood flow.

    Science.gov (United States)

    Fung, Y C; Zhuang, F Y

    1986-05-01

    For pulmonary blood flow in zone 2 condition, in which the blood pressure in the venule (pven) is lower than the alveolar gas pressure (pA), the blood exiting from the capillary sheet and entering a venule must go through a sluicing gate. The sluicing gate exists because the venule remains patent while the capillaries will collapse when the static pressure of blood falls below the alveolar gas pressure. In the original theory of sheet flow the effect of the tension in the interalveolar septa on the flow through the sluicing gate was ignored. Since the tension multiplied by the curvature of the membrane is equivalent to a lateral pressure tending to open the gate, and since the curvature of the capillary wall is high in the gate region, this effect may be important. The present analysis improves the original theory and demonstrates that the effect of membrane tension is to cause flow to increase when the venous pressure continues to decrease. The shape of the sluicing gate resembles that of a venturi tube, and can be determined by an iterative integration of the differential equations. The result forms an important link in the theory of pulmonary blood flow in zone 2 condition.

  15. Aortic pressure reduction redistributes transmural blood flow in dog left ventricle

    International Nuclear Information System (INIS)

    The authors studied the effect of graded aortic blood pressure reduction on left ventricular (LV) blood flow in anesthetized, autonomically blocked, open-chest dogs at constant heart rate and mean left atrial pressure. Aortic diastolic pressure (ADP) was lowered from rest to 90, 75, and 60 mmHg with an arteriovenous fistula. Global and regional LV blood flow was measured with radioactive microspheres. Mean LV blood flow fell stepwise from 145 ml · min-1 · 100 g-1 at rest to 116 ml · min-1 · 100 g-1 at ADP of 60 mmHg, whereas the endocardial-to-epicardial flow ratio decreased from 1.20 to 084. The transmural redistribution of LV blood flow was not accompanied by increases in LV oxygen extraction, depression of LV contractility, LV dilatation or LV electrical dysfunction and also occurred in the presence of considerable coronary vasodilator flow reserve. Electrical evidence of subendocardial ischemia appeared at ADP of 32 mmHg and an endocardial-to-epicardial flow ratio of 0.41 in a subgroup of animals. They conclude that the redistribution of LV flow during moderate aortic pressure reduction was an appropriate physiological adjustment to uneven transmural alterations in regional LV wall stress and that it preceded a more pronounced redistribution evident with myocardial ischemia

  16. Blood Pressure Measurement: Clinic, Home, Ambulatory, and Beyond

    OpenAIRE

    Drawz, Paul E; ABDALLA, MOHAMED; Rahman, Mahboob

    2012-01-01

    Blood pressure has traditionally been measured in the clinic setting using the auscultory method and a mercury sphygmomanometer. Technological advances have led to improvements in measuring clinic blood pressure and allowed for measuring blood pressures outside the clinic. This review outlines various methods for evaluating blood pressure and the clinical utility of each type of measurement. Home blood pressures and 24 hour ambulatory blood pressures have improved our ability to evaluate risk...

  17. Arterio-venous flow between monochorionic twins determined during intra-uterine transfusion. Nonlinear decay of adult red blood cells

    Energy Technology Data Exchange (ETDEWEB)

    Gemert, Martin J C van; Wijngaard, Jeroen P H M van den [Laser Centre and Department of Obstetrics, Academic Medical Centre, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam (Netherlands); Pasman, Suzanne A; Vandenbussche, Frank P H A [Division of Fetal Medicine, Department of Obstetrics, Leiden University Medical Centre, Leiden (Netherlands); Lopriore, Enrico [Division of Neonatology, Department of Pediatrics, Leiden University Medical Centre, Leiden (Netherlands)], E-mail: m.j.vangemert@amc.uva.nl

    2008-07-07

    Recently, we derived equations relating the flow of adult red blood cells through a placental arterio-venous anastomosis with intra-uterine and post-natal measured adult hemoglobin concentrations. In this letter, we re-derived the equations, now including a more realistic nonlinear decay of adult red blood cells, and re-evaluated the measurement accuracy of the arterio-venous flow and the lifetime of the red blood cells. (letter to the editor)

  18. Meal-induced changes in splanchnic blood flow and oxygen uptake in middle-aged healthy humans

    DEFF Research Database (Denmark)

    Madsen, Jan L; Søndergaard, Susanne B; Møller, Søren

    2006-01-01

    was therefore to measure the splanchnic blood flow and oxygen uptake before and after a standardized meal in a group of middle-aged normal volunteers. MATERIAL AND METHODS: Splanchnic blood flow and oxygen uptake were determined at baseline and after a 3600-kJ mixed meal in 8 healthy women (50-70 years) and 10......). A close association was found between the meal-induced peak increases in splanchnic blood flow and oxygen uptake, but the variables were not related to gender or body surface area of the subjects. CONCLUSIONS: A 3,600-kJ mixed meal induces a significant increase in splanchnic blood flow and oxygen uptake...

  19. Role of cerebral blood flow in extreme breath holding

    Directory of Open Access Journals (Sweden)

    Bain Anthony R.

    2016-01-01

    Full Text Available The role of cerebral blood flow (CBF on a maximal breath-hold (BH in ultra-elite divers was examined. Divers (n = 7 performed one control BH, and one BH following oral administration of the non-selective cyclooxygenase inhibitor indomethacin (1.2 mg/kg. Arterial blood gases and CBF were measured prior to (baseline, and at BH termination. Compared to control, indomethacin reduced baseline CBF and cerebral delivery of oxygen (CDO2 by about 26% (p < 0.01. Indomethacin reduced maximal BH time from 339 ± 51 to 319 ± 57 seconds (p = 0.04. In both conditions, the CDO2 remained unchanged from baseline to the termination of apnea. At BH termination, arterial oxygen tension was higher following oral administration of indomethacin compared to control (4.05 ± 0.45 vs. 3.44 ± 0.32 kPa. The absolute increase in CBF from baseline to the termination of apnea was lower with indomethacin (p = 0.01. These findings indicate that the impact of CBF on maximal BH time is likely attributable to its influence on cerebral H+ washout, and therefore central chemoreceptive drive to breathe, rather than to CDO2.

  20. Brain blood flow studies with single photon emission computed tomography in patients with plateau waves

    International Nuclear Information System (INIS)

    The authors studied brain blood flow with single photon emission computed tomography (SPECT) in two patients with plateau waves. The intracranial pressure and blood pressure were also monitored continuously in these patients. They included one patient with brain-tumor (rt. sphenoid ridge meningioma) and another with hydrocephalus after subarachnoid hemorrhage due to rupture of lt. internal carotid aneurysm. The intracranial pressure was monitored through an indwelling ventricular catheter attached to a pressure transducer. The blood pressure was recorded through an intraarterial catheter placed in the dorsalis pedis artery. Brain blood flow was studied with Headtome SET-011 (manufactured by Shimazu Co., Ltd.). For this flow measurement study, an intravenous injection of Xenon-133 of about 30 mCi was given via an antecubital vein. The position of the slice for the SPECT was selected so as to obtain information not only from the cerebral hemisphere but also from the brain stem : a cross section 25 deg over the orbito-meatal line, passing through the inferior aspect of the frontal horn, the basal ganglia, the lower recessus of the third ventricle and the brain stem. The results indicated that, in the cerebral hemisphere, plateau waves were accompanied by a decrease in blood flow, whereas, in the brain stem, the blood flow showed little change during plateau waves as compared with the interval phase between two plateau waves. These observations may explain why there is no rise in the blood pressure and why patients are often alert during plateau waves. (author)

  1. Characterization of Transition to Turbulence for Blood in a Straight Pipe Under Steady Flow Conditions.

    Science.gov (United States)

    Biswas, Dipankar; Casey, David M; Crowder, Douglas C; Steinman, David A; Yun, Yang H; Loth, Francis

    2016-07-01

    Blood is a complex fluid that, among other things, has been established to behave as a shear thinning, non-Newtonian fluid when exposed to low shear rates (SR). Many hemodynamic investigations use a Newtonian fluid to represent blood when the flow field of study has relatively high SR (>200 s-1). Shear thinning fluids have been shown to exhibit differences in transition to turbulence (TT) compared to that of Newtonian fluids. Incorrect prediction of the transition point in a simulation could result in erroneous hemodynamic force predictions. The goal of the present study was to compare velocity profiles near TT of whole blood and Newtonian blood analogs in a straight rigid pipe with a diameter 6.35 mm under steady flow conditions. Rheology was measured for six samples of whole porcine blood and three samples of a Newtonian fluid, and the results show blood acts as a shear thinning non-Newtonian fluid. Measurements also revealed that blood viscosity at SR = 200 s-1 is significantly larger than at SR = 1000 s-1 (13.8%, p  20%) with a maximum TKE near the pipe center at Re = 2316 ± 34 which indicated transition. In contrast, blood results showed the maximum TKE at Re = 2806 ± 109. Overall, the critical Re was delayed by ∼20% (p < 0.001) for blood compared to the Newtonian fluid. Thus, a Newtonian assumption for blood at flow conditions near transition could lead to large errors in velocity prediction for steady flow in a straight pipe. However, these results are specific to this pipe diameter and not generalizable since SR is highly dependent on pipe diameter. Further research is necessary to understand this relation in different pipe sizes, more complex geometries, and under pulsatile flow conditions.

  2. A numerical study of blood flow using mixture theory.

    Science.gov (United States)

    Wu, Wei-Tao; Aubry, Nadine; Massoudi, Mehrdad; Kim, Jeongho; Antaki, James F

    2014-03-01

    In this paper, we consider the two dimensional flow of blood in a rectangular microfluidic channel. We use Mixture Theory to treat this problem as a two-component system: One component is the red blood cells (RBCs) modeled as a generalized Reiner-Rivlin type fluid, which considers the effects of volume fraction (hematocrit) and influence of shear rate upon viscosity. The other component, plasma, is assumed to behave as a linear viscous fluid. A CFD solver based on OpenFOAM(®) was developed and employed to simulate a specific problem, namely blood flow in a two dimensional micro-channel, is studied. Finally to better understand this two-component flow system and the effects of the different parameters, the equations are made dimensionless and a parametric study is performed. PMID:24791016

  3. Mediators of increased blood flow in porcine skin

    Directory of Open Access Journals (Sweden)

    H. D. Moore

    1992-01-01

    Full Text Available Nicotinates and benzalkonium chloride (B.Cl cause inflammatory changes in human skin, thought to be dependent upon prostaglandin formation. This study has examined the effects of hexyl-nicotinate (HN and B.Cl on blood flow in porcine skin. The role of prostaglandins and interleukin (IL-1 in the blood flow response has been investigated. Blood flow was increased by both HN and B.Cl, the response to B.Cl being more protracted. Cyclooxygenase inhibitor pretreatment reduced these responses. IL-1-like biological activity was identified in normal porcine epidermis and the amounts recovered from inflamed skin were similar. Thus prostaglandin formation in HN or B.Cl-induced inflammation, if IL-1 dependent, is not associated with the loss of significant amounts of the cytokine from the epidermis.

  4. 轴流式血泵流场CFD仿真%Flow field CFD analysis of axial flow blood pump

    Institute of Scientific and Technical Information of China (English)

    谢雄; 谭建平

    2014-01-01

    In the development of axial flow blood pump,the arterial partial flow field may produce an area with very low flow shear rate,so it is necessary to consider the non-Newtonian charac-teristics of blood fluid.In this paper,a model of axial flow blood pump was established,and flow and rotate-speed’s impacts on the inlet and outlet of the flow field in the blood pump were ana-lyzed through Computational Fluid Dynamics (CFD)simulation,as wel as the influence of the guide vane on the flow field.By the pump water experiment of the designed blood pump,its out-put flow and pressure were measured;the results show that the designed blood pump is consist-ent on the law with the simulation.%在轴流式血泵的研发过程中,动脉局部流场中可能产生流动剪切率非常低的区域,因此有必要考虑血液的非牛顿特性。建立了轴流式血泵模型,通过CFD仿真分析得到血泵转速和流量的变化对血泵出入口压力分布和速度分布的影响,并采用水和甘油(2∶1)的混合流体替代血液,对设计的血泵进行驱动实验,测量了轴流式血泵输出流量和压力参数。结果表明:所设计的血泵在规律上和仿真是相符的。

  5. Doppler Assessment of Uterine Blood Flow in Recurrent Pregnancy Loss

    Directory of Open Access Journals (Sweden)

    Maryam Barzin

    2011-05-01

    Full Text Available Recurrent spontaneous abortion affects 2%-5% of"ncouples. Uterine perfusion is considered as one of the"nfactors that influences the success of implantation."nDuring the normal menstrual cycle, the impedance"nto uterine artery blood flow diminishes progressively"nduring the luteal phase, reaching the lowest values"nin the period coinciding with the implantation time."nImpedance of uterine arteries is a good indicator of"nthe possibility of a subsequent pregnancy. High blood"nflow resistance is associated with a reduced conception"nrate and women with lower pulsatility index values"nhave the highest possibility of becoming pregnant. An"nimpaired uterine perfusion could play a major role in"nthe pathogenesis of recurrent spontaneous abortion. In"nthis study, we examined sixty women with recurrent"nspontaneous abortion and a control group including"nthirty normal women with at least one previous"nuncomplicated pregnancy and without history of any"nabortion. Transvaginal sonography associated with"nDoppler flow measurement was performed during"nthe midluteal phase of a cycle in all women. The"nmeasurement of the ascending branch of both right"nand left uterine arteries was taken lateral to the cervix"nat the level of the internal os. The pulsatility and"nresistance index of both uterine arteries were calculated"nand compared in both groups. In this presentation we"nreport our finding in two groups. We also explain the"nexact method of study and present some interesting"ncases

  6. Cerebrospinal fluid ionic regulation, cerebral blood flow, and glucose use during chronic metabolic alkalosis

    Energy Technology Data Exchange (ETDEWEB)

    Schroeck, H.K.; Kuschinsky, W. (Univ. of Bonn (Germany, F.R.))

    1989-10-01

    Chronic metabolic alkalosis was induced in rats by combining a low K+ diet with a 0.2 M NaHCO3 solution as drinking fluid for either 15 or 27 days. Local cerebral blood flow and local cerebral glucose utilization were measured in 31 different structures of the brain in conscious animals by means of the iodo-(14C)antipyrine and 2-(14C)deoxy-D-glucose method. The treatment induced moderate (15 days, base excess (BE) 16 mM) to severe (27 days, BE 25 mM) hypochloremic metabolic alkalosis and K+ depletion. During moderate metabolic alkalosis no change in cerebral glucose utilization and blood flow was detectable in most brain structures when compared with controls. Cerebrospinal fluid (CSF) K+ and H+ concentrations were significantly decreased. During severe hypochloremic alkalosis, cerebral blood flow was decreased by 19% and cerebral glucose utilization by 24% when compared with the control values. The decrease in cerebral blood flow during severe metabolic alkalosis is attributed mainly to the decreased cerebral metabolism and to a lesser extent to a further decrease of the CSF H+ concentration. CSF K+ concentration was not further decreased. The results show an unaltered cerebral blood flow and glucose utilization together with a decrease in CSF H+ and K+ concentrations at moderate metabolic alkalosis and a decrease in cerebral blood flow and glucose utilization together with a further decreased CSF H+ concentration at severe metabolic alkalosis.

  7. Temporal changes in cardiac function and cerebral blood flow during sequential postmenopausal hormone replacement

    DEFF Research Database (Denmark)

    Sørensen, M B; Fritz-Hansen, T; Jensen, H H;

    2001-01-01

    OBJECTIVE: The purpose was to assess the temporal changes in cardiac function and cerebral blood flow during postmenopausal administration of estrogen with and without progestogen. STUDY DESIGN: Sixteen postmenopausal volunteers were assessed during estradiol plus sequential norethindrone acetate...... and placebo in two 12-week periods. Temporal changes were measured by magnetic resonance flow mapping 8 times. RESULTS: Systemic vascular resistance was reduced during estradiol (-6.9%; P ... (maximum increase, 5.2%; P Cerebral blood flow was reduced after 9 weeks of hormone replacement therapy (-37 mL/min; P =.01) but increased to baseline after...

  8. Quantitative blood flux measurement using MUSIC

    Science.gov (United States)

    Yousefi, Siavash; Qin, Jia; Wang, Ruikang K.

    2014-03-01

    In this paper, we propose a method to quantify red blood cell (RBC) flow through capillary loops and microvessels using optical microangiography (OMAG). Current existing methods of capillary flow quantification either require a very long scanning time (~few minutes) or a large acquisition number per location (+100 scans per location) to form a highresolution spectral estimation. We utilize a model-based super-resolution spectral estimation technique based on principle of orthogonality to quantify moving RBCs within a voxel. The scanning protocol required for our method is very similar to 3D ultrahigh sensitive OMAG that requires few scans per location (8) and can be performed in few seconds that makes it applicable for in vivo experiments. This method is analogous to power Doppler in ultrasonography and estimates the number of red blood cells passing through the beam as opposed to the velocity of the particles. The technique is tested both qualitatively and quantitatively by using OMAG to image microcirculation within mouse ear flap in vivo.

  9. Heart blood flow simulation: a perspective review.

    Science.gov (United States)

    Doost, Siamak N; Ghista, Dhanjoo; Su, Boyang; Zhong, Liang; Morsi, Yosry S

    2016-01-01

    Cardiovascular disease (CVD), the leading cause of death today, incorporates a wide range of cardiovascular system malfunctions that affect heart functionality. It is believed that the hemodynamic loads exerted on the cardiovascular system, the left ventricle (LV) in particular, are the leading cause of CVD initiation and propagation. Moreover, it is believed that the diagnosis and prognosis of CVD at an early stage could reduce its high mortality and morbidity rate. Therefore, a set of robust clinical cardiovascular assessment tools has been introduced to compute the cardiovascular hemodynamics in order to provide useful insights to physicians to recognize indicators leading to CVD and also to aid the diagnosis of CVD. Recently, a combination of computational fluid dynamics (CFD) and different medical imaging tools, image-based CFD (IB-CFD), has been widely employed for cardiovascular functional assessment by providing reliable hemodynamic parameters. Even though the capability of CFD to provide reliable flow dynamics in general fluid mechanics problems has been widely demonstrated for many years, up to now, the clinical implications of the IB-CFD patient-specific LVs have not been applicable due to its limitations and complications. In this paper, we review investigations conducted to numerically simulate patient-specific human LV over the past 15 years using IB-CFD methods. Firstly, we divide different studies according to the different LV types (physiological and different pathological conditions) that have been chosen to reconstruct the geometry, and then discuss their contributions, methodologies, limitations, and findings. In this regard, we have studied CFD simulations of intraventricular flows and related cardiology insights, for (i) Physiological patient-specific LV models, (ii) Pathological heart patient-specific models, including myocardial infarction, dilated cardiomyopathy, hypertrophic cardiomyopathy and hypoplastic left heart syndrome. Finally, we

  10. Effect of pregnancy on regional cerebral blood flow

    International Nuclear Information System (INIS)

    Regional cerebral blood flow (r-CBF) of 10 pregnant women were quantified by 133Xe SPECT study with inhalation method before and after artificial abortion. During pregnancy, value of r-CBF in each region except occipital lobe was significantly higher than that of the post abortion. Arterial blood gas was analyzed after SPECT procedure. Pco2 concentration increased significantly after artificial abortion. Although its mechanism is unknown, our preliminary work demonstrates that r-CBF increased by pregnancy. (author)

  11. Luteal blood flow in patients undergoing GnRH agonist long protocol

    Directory of Open Access Journals (Sweden)

    Takasaki Akihisa

    2011-01-01

    Full Text Available Abstract Background Blood flow in the corpus luteum (CL is closely related to luteal function. It is unclear how luteal blood flow is regulated. Standardized ovarian-stimulation protocol with a gonadotropin-releasing hormone agonist (GnRHa long protocol causes luteal phase defect because it drastically suppresses serum LH levels. Examining luteal blood flow in the patient undergoing GnRHa long protocol may be useful to know whether luteal blood flow is regulated by LH. Methods Twenty-four infertile women undergoing GnRHa long protocol were divided into 3 groups dependent on luteal supports; 9 women were given ethinylestradiol plus norgestrel (Planovar orally throughout the luteal phase (control group; 8 women were given HCG 2,000 IU on days 2 and 4 day after ovulation induction in addition to Planovar (HCG group; 7 women were given vitamin E (600 mg/day orally throughout the luteal phase in addition to Planovar (vitamin E group. Blood flow impedance was measured in each CL during the mid-luteal phase by transvaginal color-pulsed-Doppler-ultrasonography and was expressed as a CL-resistance index (CL-RI. Results Serum LH levels were remarkably suppressed in all the groups. CL-RI in the control group was more than the cutoff value (0.51, and only 2 out of 9 women had CL-RI values Conclusion Patients undergoing GnRHa long protocol had high luteal blood flow impedance with very low serum LH levels. HCG administration improved luteal blood flow impedance. This suggests that luteal blood flow is regulated by LH.

  12. Spatial heterogeneity of blood flow in the dog heart. II. Temporal stability in response to adrenergic stimulation.

    Science.gov (United States)

    Deussen, A; Flesche, C W; Lauer, T; Sonntag, M; Schrader, J

    1996-07-01

    The effects of adrenergic stimulation on local myocardial blood flow in the left ventricle were studied in 13 anaesthetized Beagle dogs using the tracer microsphere technique. Adrenergic stimulation was induced by intravenous infusion of orciprenaline (1-2 microg kg-1 min-1) over 15 min or by electrical stimulation of the left ansa subclavia (10 Hz, 1 ms, 4-8 V) over 5 min. Local myocardial blood flow was analysed in 256 samples with an average (+/-SD) mass of 318+/-49 mg from the left ventricular myocardium using a standardized dissection procedure. Orciprenaline increased the average myocardial blood flow from 0.85+/-0.18 to 1.73+/-0.27 ml min-1 g-1, while oxygen consumption and the pressure-rate product increased by 129 and 119% respectively. The coefficients of variation of local myocardial blood flow, a measure of spatial blood flow heterogeneity, were 0.21 and 0.18 under control and orciprenaline respectively. Except for a slight transmural gradient (endomyocardium/epimyocardium flow ratio 1.19) myocardial blood flow did not exhibit significant spatial gradients. Stimulation with orciprenaline increased the average blood flow in all regions of the left ventricle by comparable extents. However, local blood flow during orciprenaline was significantly lower in samples from regions which had a lower blood flow under resting control conditions. A significant positive relationship was obtained between local myocardial blood flow under resting conditions and orciprenaline (r=0.45+/-0.18). Moreover, after recovery from orciprenaline stimulation (i.e. 40-112 min after the end of orciprenaline infusion) local myocardial blood flow exhibited a high degree of correlation with local flow before orciprenaline (r=0.71+/-0.08). Comparable results were obtained with electrical stimulation of the left ansa subclavia. For the comparison stimulation vs. control, the correlation coefficient of local blood flow was 0.52+/-0.04 and for recovery vs. control 0.77+/-0.06. From these

  13. Fontan Outcomes and Pulmonary Blood Flow at Birth.

    Science.gov (United States)

    Evans, William N; Acherman, Ruben J; Reardon, Leigh C; Ciccolo, Michael L; Galindo, Alvaro; Rothman, Abraham; Winn, Brody J; Yumiaco, Noel S; Restrepo, Humberto

    2016-01-01

    We previously noted, in a small group of post-Fontan patients, a possible association between hepatic fibrosis scores and the status of pulmonary blood flow at birth. To further explore this observation, we examined data from all Fontan patients seen in our center from July 2010 to March 2015. We identified 200 patients for analysis. Of the 200 patients, 56 underwent transvenous-hepatic biopsy. Of the 200 patients, 13 (6.5%) had protein-losing enteropathy. We divided both the 56 biopsy patients and the entire cohort of 200 patients into 4 groups: (1) unobstructed pulmonary blood flow at birth with functional left ventricles, (2) unobstructed pulmonary blood flow at birth with functional right ventricles, (3) obstructed pulmonary blood flow at birth with functional left ventricles, and (4) obstructed pulmonary blood flow at birth with functional right ventricles. Analysis of the 56 liver-biopsy patient groups showed median hepatic total-fibrosis scores for the 4 groups of 2 (0-6), 2 (0-8), 3 (2-6), and 4 (1-8), respectively, with statistical significance between groups 4 and 1 (p = 0.031). For the entire cohort of 200 patients, we analyzed the incidence of protein-losing enteropathy for each of the four groups and found protein-losing enteropathy percent occurrences of 0, 2.9, 8.8, and 16.1, respectively, with statistical significance between groups 4 and 2 (p = 0.031) and between groups 4 and 1 (p = 0.025). A history of obstructed pulmonary blood flow at birth, coupled with a functional right ventricle, may predict a poorer long-term Fontan outcome.

  14. Cerebral blood flow in asymptomatic individuals

    International Nuclear Information System (INIS)

    We studied the relationship between cortical grey matter flow (CBF) and age, cerebrovascular risk factors and the severity of subcortical hypersignals (HS, hyperintensity score in MRI) in 47 asymptomatic subjects with cerebrovascular risk factors. Multiple regression analysis revealed that HS was most strongly related to CBF, and that hematocrit, age and evidence of ischemic change detected in the electrocardiogram also appeared to be independent determinants of CBF. Both the severity and location of hypersignals were correlated with CBF. The most significant negative correlation observed was that between CBF and HS in the basal ganglia-thalamic region, where the degree of signal abnormality was modest. Decreased CBF in asymptomatic subjects with cerebrovascular risk factors may be related to microcirculatory disturbance associated with elevated hematocrit and an increase in the number of risk factors, and functional suppression of cerebral cortex due to the neuronal disconnection associated with subcortical lesions. In addition, impaired cerebral circulation may be related to MRI signal abnormalities. (author)

  15. Pulmonary blood flow distribution in transposition of the great arteries

    International Nuclear Information System (INIS)

    Pulmonary blood flow distribution was studied by scintillation scanning of the lungs after the infusion of iodine-131-labeled macroaggregates of human albumin before and after the Mustard operation in 53 patients with transposition of the great arteries. The patients were classified as follows: Group 1 (24 infants with uncomplicated transposition of the great arteries); Group II (18 patients with transposition and ventricular septal defect); and Group III (11 patients with transposition, ventricular septal defect and pulmonary obstruction). Before operation, 21 patients had a normal distribution of pulmonary blood flow, 10 had preferential flow to the right lung and 2 had preferential flow to the left lung. After operation, 19 had a normal pattern of pulmonary blood flow, 21 had preferential flow to the right lung and 3 had preferential flow to the left lung. The scanning studies have proved helpful in follow-up of patients to rule out recurrence of the shunt, pulmonary or systemic venous obstruction, development of pulmonary hypertension and occlusion of a palliative systemic-pulmonary shunt

  16. Flow of Red Blood Cells in Stenosed Microvessels

    Science.gov (United States)

    Vahidkhah, Koohyar; Balogh, Peter; Bagchi, Prosenjit

    2016-06-01

    A computational study is presented on the flow of deformable red blood cells in stenosed microvessels. It is observed that the Fahraeus-Lindqvist effect is significantly enhanced due to the presence of a stenosis. The apparent viscosity of blood is observed to increase by several folds when compared to non-stenosed vessels. An asymmetric distribution of the red blood cells, caused by geometric focusing in stenosed vessels, is observed to play a major role in the enhancement. The asymmetry in cell distribution also results in an asymmetry in average velocity and wall shear stress along the length of the stenosis. The discrete motion of the cells causes large time-dependent fluctuations in flow properties. The root-mean-square of flow rate fluctuations could be an order of magnitude higher than that in non-stenosed vessels. Several folds increase in Eulerian velocity fluctuation is also observed in the vicinity of the stenosis. Surprisingly, a transient flow reversal is observed upstream a stenosis but not downstream. The asymmetry and fluctuations in flow quantities and the flow reversal would not occur in absence of the cells. It is concluded that the flow physics and its physiological consequences are significantly different in micro- versus macrovascular stenosis.

  17. Daily rhythms in renal blood flow and urine production rate in the near-term sheep fetus

    NARCIS (Netherlands)

    Poortinga, FMI; Aarnoudse, JG

    2000-01-01

    Daily rhythmicity of renal blood flow (RBF) and urine flow (UF) was studied in fetal sheep between 121-125 d of gestation. Fetal arterial blood pressure, heart rate, UF, and right RBF were measured continuously for 24-h periods in 10 sheep, Rhythmic variations during a 24-h period were found for all

  18. Functional morphology and patterns of blood flow in the heart of Python regius.

    Science.gov (United States)

    Starck, J Matthias

    2009-06-01

    Brightness-modulated ultrasonography, continuous-wave Doppler, and pulsed-wave Doppler-echocardiography were used to analyze the functional morphology of the undisturbed heart of ball pythons. In particular, the action of the muscular ridge and the atrio-ventricular valves are key features to understand how patterns of blood flow emerge from structures directing blood into the various chambers of the heart. A step-by-step image analysis of echocardiographs shows that during ventricular diastole, the atrio-ventricular valves block the interventricular canals so that blood from the right atrium first fills the cavum venosum, and blood from the left atrium fills the cavum arteriosum. During diastole, blood from the cavum venosum crosses the muscular ridge into the cavum pulmonale. During middle to late systole the muscular ridge closes, thus prohibiting further blood flow into the cavum pulmonale. At the same time, the atrio-ventricular valves open the interventricular canal and allow blood from the cavum arteriosum to flow into the cavum venosum. In the late phase of ventricular systole, all blood from the cavum pulmonale is pressed into the pulmonary trunk; all blood from the cavum venosum is pressed into both aortas. Quantitative measures of blood flow volume showed that resting snakes bypass the pulmonary circulation and shunt about twice the blood volume into the systemic circulation as into the pulmonary circulation. When digesting, the oxygen demand of snakes increased tremendously. This is associated with shunting more blood into the pulmonary circulation. The results of this study allow the presentation of a detailed functional model of the python heart. They are also the basis for a functional hypothesis of how shunting is achieved. Further, it was shown that shunting is an active regulation process in response to changing demands of the organism (here, oxygen demand). Finally, the results of this study support earlier reports about a dual pressure

  19. A Model of Anterograde Oxygenated Lung Blood Flow in Acardia.

    Science.gov (United States)

    Marinakis, Sotirios; Burki, Marco; Abdel-Sayed, Saad; von Segesser, Ludwig Karl

    2016-01-01

    In extreme situations such as hyperacute rejection of heart transplant or major heart trauma, heart explantation and extracorporeal membrane oxygenation (ECMO) hemodynamic support might be the only means for survival. In our previous model of acardia, pulmonary artery (PA) was clamped and did not receive any anterograde blood flow. A model of anterograde PA perfusion might be necessary to avoid ischemic pulmonary damage in prolonged ECMO in acardia. The aim of this study was to describe the surgical technique and to determine the feasibility of an anterograde lung perfusion in acardia through the anastomosis of the right internal mammary artery (RIMA) to the PA. A venoarterial cardiopulmonary bypass was established in three pigs (72 ± 2.6 kg) by the transjugular insertion to the caval axis of a double-staged cannula with carotid artery return. Heart was excised and ECMO was established as previously reported. Right internal mammary artery was harvested and after measurement of its output (93.3 ± 5.8 ml/min, representing 2.17% ± 0.15% of total pump flow), it was anastomosed to PA. Right internal mammary artery anastomosis to PA is a feasible, safe, and easy to perform maneuver assuring an anterograde lung perfusion in acardia. PMID:27442854

  20. High speed optical holography of retinal blood flow

    Science.gov (United States)

    Pellizzari, M.; Simonutti, M.; Degardin, J.; Sahel, J.-A.; Fink, M.; Paques, M.; Atlan, M.

    2016-08-01

    We performed non-invasive video imaging of retinal blood flow in a pigmented rat by holographic interferometry of near-infrared laser light backscattered by retinal tissue, beating against an off-axis reference beam sampled at a frame rate of 39 kHz with a high throughput camera. Local Doppler contrasts emerged from the envelopes of short-time Fourier transforms and the phase of autocorrelation functions of holograms rendered by Fresnel transformation. This approach permitted imaging of blood flow in large retinal vessels (30 microns diameter) over 400 by 400 pixels with a spatial resolution of 8 microns and a temporal resolution of 6.5 ms.

  1. High speed optical holography of retinal blood flow

    CERN Document Server

    Pellizzari, Mathilde; Degardin, Julie; Sahel, Jose-Alain; Fink, Mathias; Paques, Michel; Atlan, Michael

    2016-01-01

    We performed non-invasive video imaging of retinal blood flow in a pigmented rat by holographic interferometry of near-infrared laser light backscattered by retinal tissue, beating against an off-axis reference beam sampled at a frame rate of 39 kHz with a high throughput camera. Local Doppler contrasts emerged from the envelopes of short-time Fourier transforms and the phase of autocorrelation functions of holograms rendered by Fresnel transformation. This approach permitted imaging of blood flow in large retinal vessels (30 microns diameter) over 400 by 400 pixels with a spatial resolution of 8 microns and a temporal resolution of 6.5 ms.

  2. Metabolic control of muscle blood flow during exercise in humans

    DEFF Research Database (Denmark)

    Boushel, Robert Christopher

    2003-01-01

    and the vasculature that induce vasodilation. A link between muscle metabolic events and microvascular control of blood flow is illustrated by local dilation of terminal arterioles during contraction of muscle fibers and conduction of vasodilation upstream. Endothelial-derived vasodilator mechanisms are known...... to exert control of muscle vasodilation. Adenosine, nitric oxide (NO), prostacyclin (PGI2), and endothelial-derived hyperpolarization factor (EDHF) are possible mediators of muscle vasodilation during exercise. In humans, adenosine has been shown to contribute to functional hyperemia as blood flow...

  3. Oscillometric blood pressure measurements: A signal analysis

    Science.gov (United States)

    Barbé, K.; Van Moer, W.; Lauwers, L.

    2010-07-01

    In this paper, the oscillometric waveform measured by automatic non-invasive blood pressure meters (NIBP) is analyzed by transforming the data from the time domain to the frequency domain. The signal's spectrum of the oscillometric waveform is in current literature badly understood or explored. The only known link between the oscillometric waveform and the blood pressure is the maximum of the oscillometry's envelope equalling the mean arterial pressure (MAP). This link is established under the assumption that the oscillometry is an AM-signal. Unfortunately, computing the MAP is difficult in practice due to the non-sinusoidal nature of the actual measured signals. In this paper, we construct the best AM-signal approximation of the oscillometry and explore its use to compute the MAP.

  4. Non Invasive Measurement of Systolic Blood Pressure in Rats: A Simple Technique

    OpenAIRE

    Maria Pauline; Avadhany, Sandhya T.; K.N. Maruthy

    2011-01-01

    Background: Non invasive, simple and economical instrument to measure blood pressure in r365-ats is important in cardiovascular research. Methods: Systolic blood pressure measuring instrument was fabricated using a tail cuff, photoplethysmograph, pressure transducer and PC with Biopac Software for recording. Tail cuff was used to occlude the tail artery, photoplethysmograph picked the blood flow pulses in the rat tail and the pressure transducer measured the cuff pressure and converted it int...

  5. Blood pressure and mesenteric blood flow in the rat during infusion of biogenic amines. Influence of a supralethal irradiation

    International Nuclear Information System (INIS)

    The action of biogenic amines (noradrenaline, dopamine), infused at different concentration into the aorta of the urethane anesthetized control and irradiated rats for 2 min., was followed on the basis of systemic blood pressure and mesenteric blood flow. The mesenteric blood flow was measured by means of an electromagnetic flow meter. The changes observed i.e. after dopamine an increase in pressure and flow, after noradrenaline an increase in pressure and a decrease in flow with an increase after infusion had been stopped, correspond to those obtained in larger animals. In many, but not in all cases, the response is proportional to the log of the concentration of the amine infused. Irradiation with 2 kR, i.e. a dose which causes the animals to die from the gastrointestinal syndrome after 3 days modified the response to dopamine and noradrenaline. The changes are, for noradrenaline, a greater pressure and a lower flow responses and for dopamine a greater pressure response at low and middle doses

  6. Cerebral blood flow in acute and chronic ischemic stroke using xenon-133 inhalation tomography

    DEFF Research Database (Denmark)

    Vorstrup, S; Paulson, O B; Lassen, N A

    1986-01-01

    Serial measurements of cerebral blood flow (CBF) were performed in 12 patients with acute symptoms of ischemic cerebrovascular disease. CBF was measured by xenon-133 inhalation and single photon emission computer tomography. Six patients had severe strokes and large infarcts on the CT scan. They...

  7. The effect of intravitreal bevacizumab on ocular blood flow in diabetic retinopathy and branch retinal vein occlusion as measured by laser speckle flowgraphy

    Directory of Open Access Journals (Sweden)

    Nitta F

    2014-06-01

    Full Text Available Fumihiko Nitta,1 Hiroshi Kunikata,1,2 Naoko Aizawa,1 Kazuko Omodaka,1 Yukihiro Shiga,1 Masayuki Yasuda,1 Toru Nakazawa1–31Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan; 2Department of Retinal Disease Control, Tohoku University Graduate School of Medicine, Sendai, Japan; 3Department of Advanced Ophthalmic Medicine, Tohoku University Graduate School of Medicine, Sendai, JapanBackground: This study evaluated the effect of intravitreal injection of bevacizumab (IVB on macular edema associated with diabetic retinopathy (DME or branch retinal vein occlusion (BRVOME using laser speckle flowgraphy.Methods: A comparative interventional study of 25 eyes from 22 patients with macular edema (DME group: 12 eyes; BRVOME group: 13 eyes who underwent IVB. Mean blur rate (MBR was measured in the retinal artery, retinal vein, optic nerve head (ONH, and choroid before and after IVB. Results: In the BRVOME group, there was no significant change in MBR in the retinal artery, retinal vein or ONH, but choroidal MBR decreased significantly (P=0.04. In the DME group, the MBR in the retinal artery, retinal vein, ONH, and choroid decreased significantly (P=0.02, P=0.04, P<0.001, and P=0.04, respectively. In the DME group, pre-IVB MBR in the ONH was significantly correlated with post-IVB foveal thickness (R= -0.71, P=0.002. There was no such correlation in the BRVOME group in the ONH.Conclusion: IVB had a suppressive effect on circulation in eyes with DME but not in those with BRVOME. This suggests that this noninvasive and objective biomarker may be a useful part of pre-IVB evaluations and decision-making in DME.Keywords: macular edema, mean blur rate, optic nerve head, biomarker, ocular circulation

  8. Direct detection of red blood cell fragments: a new flow cytometric method to evaluate hemolysis in blood pumps.

    Science.gov (United States)

    Linneweber, J; Chow, T W; Takano, T; Maeda, T; Nonaka, K; Schulte-Eistrup, S; Kawahito, S; Elert, O; Moake, J L; Nosé, Y

    2001-01-01

    Pump induced hemolysis is presently evaluated by measuring plasma free hemoglobin (fHb). However, this method has disadvantages because quantification of fHb depends on hematocrit (HCT) and hemoglobin (Hb) levels. The aim of this work was to devise a hemoglobin independent method, capable of quantifying cell trauma directly by measuring the number of red blood cell (RBC) fragments. Whole blood flow cytometry was used to quantify circulating RBC fragments derived from a roller pump (Sarns, Inc. Model 2 M 6,002) and a centrifugal pump (Gyro C1E3, Kyocera Corp.). The pumps were tested in a mock circuit for 2 hr (5 L/min flow against 100 mm Hg pressure head). Red blood cell fragments were quantified by a phycoerythrin (PE) labeled glycophorin A antibody specific for erythrocytes. Red blood cell fragments were smaller than the intact RBC population and overlapped in size with the platelet population (based on forward- and side-light scattering measurements). For the roller pump, the values for RBC fragments increased from 1,090 +/- 260/microl at 0 min to 14,880 +/- 5,900/microl after 120 min. In contrast, using the centrifugal pump, there was little increase in RBC fragments (from 730 +/- 270/microl at 0 min to 1,400 +/- 840/microl after 120 min). Flow cytometry can be used for the rapid, sensitive, hemoglobin independent evaluation of pump induced RBC trauma.

  9. Regulation of regional cerebral blood flow during and between migraine attacks

    DEFF Research Database (Denmark)

    Lauritzen, M; Olsen, T S; Lassen, N A;

    1983-01-01

    in the normally perfused brain. Blood pressure autoregulation was normal in all brain regions. Regional blood flow increase in response to physiological activation was severely impaired in the hypoperfused brain areas, whereas neighboring normally perfused regions reacted normally. Confinement of the regulation......Cerebrovascular reactivity to voluntary hyperventilation, moderate hypertension, and physiological activation was studied in nine patients during induced migraine attacks and in four patients between their attacks. Regional cerebral blood flow was measured by the xenon 133 injection technique...... abnormalities to the area of the oligemia supports our suggestion that the blood flow changes are caused by a change in local metabolism. Between attacks of migraine, the patients had normal regulation of brain circulation....

  10. Blood Pump Development Using Rocket Engine Flow Simulation Technology

    Science.gov (United States)

    Kiris, Cetin C.; Kwak, Dochan

    2002-01-01

    This viewgraph presentation provides information on the transfer of rocket engine flow simulation technology to work involving the development of blood pumps. Details are offered regarding the design and requirements of mechanical heart assist devices, or VADs (ventricular assist device). There are various computational fluid dynamics issues involved in the visualization of flow in such devices, and these are highlighted and compared to those of rocket turbopumps.

  11. Validation of an axial flow blood pump: computational fluid dynamics results using particle image velocimetry.

    Science.gov (United States)

    Su, Boyang; Chua, Leok Poh; Wang, Xikun

    2012-04-01

    A magnetically suspended axial flow blood pump is studied experimentally in this article. The pump casing enclosed a three-blade straightener, a two-blade impeller shrouded by a permanent magnet-embedded cylinder, and a three-blade diffuser. The internal flow fields were simulated earlier using computational fluid dynamics (CFD), and the pump characteristic curves were determined. The simulation results showed that the internal flow field was basically streamlined, except the diffuser region. Particle image velocimetry (PIV) measurement of the 1:1 pump model was conducted to validate the CFD result. In order to ensure the optical access, an acrylic prototype was fabricated with the impeller driven by a servomotor instead, as the magnet is opaque. In addition to the transparent model, the blood analog fluid with the refractive index close to that of acrylic was used to avoid refraction. According to the CFD results, the axial flow blood pump could generate adequate pressure head at the rotating speed of 9500rpm and flow rate of 5L/min, and the same flow condition was applied during the PIV measurement. Through the comparisons, it was found that the experimental results were close to those obtained by CFD and had thus validated the CFD model, which could complement the limitation of the measurement in assessing the more detailed flow fields of the axial flow pump.

  12. Validation of an axial flow blood pump: computational fluid dynamics results using particle image velocimetry.

    Science.gov (United States)

    Su, Boyang; Chua, Leok Poh; Wang, Xikun

    2012-04-01

    A magnetically suspended axial flow blood pump is studied experimentally in this article. The pump casing enclosed a three-blade straightener, a two-blade impeller shrouded by a permanent magnet-embedded cylinder, and a three-blade diffuser. The internal flow fields were simulated earlier using computational fluid dynamics (CFD), and the pump characteristic curves were determined. The simulation results showed that the internal flow field was basically streamlined, except the diffuser region. Particle image velocimetry (PIV) measurement of the 1:1 pump model was conducted to validate the CFD result. In order to ensure the optical access, an acrylic prototype was fabricated with the impeller driven by a servomotor instead, as the magnet is opaque. In addition to the transparent model, the blood analog fluid with the refractive index close to that of acrylic was used to avoid refraction. According to the CFD results, the axial flow blood pump could generate adequate pressure head at the rotating speed of 9500rpm and flow rate of 5L/min, and the same flow condition was applied during the PIV measurement. Through the comparisons, it was found that the experimental results were close to those obtained by CFD and had thus validated the CFD model, which could complement the limitation of the measurement in assessing the more detailed flow fields of the axial flow pump. PMID:22040356

  13. Blood flow measurements in the irradiated pig skin using {beta} emitters radionuclides; Mesure de la circulation sanguine cutanee chez le porc irradie a l`aide de radioisotopes emetteurs {beta}

    Energy Technology Data Exchange (ETDEWEB)

    Daburon, F.; Lefaix, J.L.; Leplat, J.J.; Fayart, G.; Delacroix, D.; Le Thanh, P.

    1997-01-01

    Non invasive methods of study of the skin blood flow are numerous, but generally do not give any indication on the cutaneous micro-circulatory flow, except for cutaneous laser Doppler. The isotopic exploration of the skin with injected {gamma} radionuclides, even of weak energy, doe snot allow to characterize the skin blood flow, because of the important contribution of the subcutaneous tissues. The use of {beta} emitters energy spectrum, analyzed by different quantitative methods, are proportional to the thickness of the screen localized between the radioactive source and detector. Using simple and complex phantoms composed of tissue equivalent screens, with {sup 32}P sources placed at different depths, it was possible to study the degradation of {beta} spectra, simulating respectively the sub-epidermis and sub-dermis vascular levels. A modelization and an experimental study in-vivo are proposed in this work, with {sup 32}P phosphate administered intravenously in pigs. (author).

  14. Blood Flow Restricted Exercise and Vascular Function

    OpenAIRE

    Masahiro Horiuchi; Koichi Okita

    2012-01-01

    It is established that regular aerobic training improves vascular function, for example, endothelium-dependent vasodilatation and arterial stiffness or compliance and thereby constitutes a preventative measure against cardiovascular disease. In contrast, high-intensity resistance training impairs vascular function, while the influence of moderate-intensity resistance training on vascular function is still controversial. However, aerobic training is insufficient to inhibit loss in muscular str...

  15. Low resource processing algorithms for laser Doppler blood flow imaging.

    Science.gov (United States)

    Nguyen, Hoang C; Hayes-Gill, Barrie R; Zhu, Yiqun; Crowe, John A; He, Diwei; Morgan, Stephen P

    2011-07-01

    The emergence of full field laser Doppler blood flow imaging systems based on CMOS camera technology means that a large amount of data from each pixel in the image needs to be processed rapidly and system resources need to be used efficiently. Conventional processing algorithms that are utilized in single point or scanning systems are therefore not an ideal solution as they will consume too much system resource. Two processing algorithms that address this problem are described and efficiently implemented in a field programmable gate array. The algorithms are simple enough to use low system resource but effective enough to produce accurate flow measurements. This enables the processing unit to be integrated entirely in an embedded system, such as in an application-specific integrated circuit. The first algorithm uses a short Fourier transformation length (typically 8) but averages the output multiple times (typically 128). The second method utilizes an infinite impulse response filter with a low number of filter coefficients that operates in the time domain and has a frequency-weighted response. The algorithms compare favorably with the reference standard 1024 point fast Fourier transform in terms of both resource usage and accuracy. The number of data words per pixel that need to be stored for the algorithms is 1024 for the reference standard, 8 for the short length Fourier transform algorithm and 5 for the algorithm based on the infinite impulse response filter. Compared to the reference standard the error in the flow calculation is 1.3% for the short length Fourier transform algorithm and 0.7% for the algorithm based on the infinite impulse response filter. PMID:21316289

  16. Renal cortical and medullary blood flow responses to altered NO availability in humans

    DEFF Research Database (Denmark)

    Damkjær, Mads; Vafaee, Manoucher; Møller, Michael L;

    2010-01-01

    , tissue layers with a thickness of one voxel were eliminated stepwise from the external surface of the VOI (voxel peeling), and the blood flow subsequently was determined in each new, reduced VOI. Blood flow in the shrinking VOIs decreased as the number of cycles of voxel peeling increased. After 4......-5 cycles, blood flow was not reduced further by additional voxel peeling. This volume-insensitive flow was measured to be 2.30 ± 0.17 ml·g tissue(-1)·min(-1) during the control period; it increased during infusion of glyceryl nitrate to 2.97 ± 0.18 ml·g tissue(-1)·min(-1) (P

  17. Emesis, radiation exposure, and local cerebral blood flow in the ferret

    Energy Technology Data Exchange (ETDEWEB)

    Tuor, U.I.; Kondysar, M.H.; Harding, R.K.

    1988-06-01

    We examined the sensitivity of the ferret to emetic stimuli and the effect of radiation exposure near the time of emesis on local cerebral blood flow. Ferrets vomited following the administration of either apomorphine (approx 45% of the ferrets tested) or peptide YY (approx 36% of those tested). Exposure to radiation was a very potent emetic stimulus, but vomiting could be prevented by restraint of the hindquarters of the ferret. Local cerebral blood flow was measured using a quantitative autoradiographic technique and with the exception of several regions in the telencephalon and cerebellum, local cerebral blood flow in the ferret was similar to that in the rat. In animals with whole-body exposure to moderate levels of radiation (4 Gy of /sup 137/Cs), mean arterial blood pressure was similar to that in the control group. However, 15-25 min following irradiation there was a general reduction of local cerebral blood flow ranging from 7 to 33% of that in control animals. These cerebral blood flow changes likely correspond to a reduced activation of the central nervous system.

  18. Noninvasive measurement of pulmonary blood volume

    International Nuclear Information System (INIS)

    In noninvasive estimation of pulmonary blood volume by radionuclide-angiocardiography, a formula was derived from experiments with heart-lung model, and in vivo experiments PBV = CO x PPT x 0.77. The pulmonary blood volume estimated clinically by this formula was in good agreement with the results obtained invasively before. The compliance (δV/δP) of the pulmonary ''venous'' system was calculated by simultaneous measurement of pressure changes in lung field on leg elevation and changes in pulmonary arterial wedge pressure with Swan-Ganz catheter. The compliances which were calculated in 35 cases of heart diseases by this method were in a considerably good agreement with those which were assessed by analysis of a pulmonary arterial wedge pressure tracing. (Ueda, J.)

  19. History of International Society for Cerebral Blood Flow and Metabolism

    DEFF Research Database (Denmark)

    Paulson, Olaf B; Kanno, Iwao; Reivich, Martin;

    2012-01-01

    dealing with CBF and metabolism were arranged, and the fast growing research led to a demand for a specialized journal. In this scientific environment, the International Society for Cerebral Blood Flow and Metabolism (ISCBFM) and its official Journal of Cerebral Metabolism were established in 1981 and has...

  20. Renal blood flow in experimental septic acute renal failure

    NARCIS (Netherlands)

    Langenberg, C.; Wan, L.; Egi, M.; May, C. N.; Bellomo, R.

    2006-01-01

    Reduced renal blood flow (RBF) is considered central to the pathogenesis of septic acute renal failure (ARF). However, no controlled experimental studies have continuously assessed RBF during the development of severe septic ARF. We conducted a sequential animal study in seven female Merino sheep. F

  1. Development of a miniature intraventricular axial flow blood pump.

    Science.gov (United States)

    Yamazaki, K; Umezu, M; Koyanagi, H; Outa, E; Ogino, S; Otake, Y; Shiozaki, H; Fujimoto, T; Tagusari, O; Kitamura, M

    1993-01-01

    A new intraventricular axial flow blood pump has been designed and developed as a totally implantable left ventricular assist device (LVAD). This pump consists of an impeller combined with a guide-vane, a tube housing, and a DC motor. The pump is introduced into the LV cavity through the LV apex, and the outlet cannula is passed antegrade across the aortic valve. Blood is withdrawn from the LV through the inlet ports at the pump base, and discharged to the ascending aorta. Our newly developed axial flow pump system has the following advantages: 1) it is a simple and compact system, 2) minimal blood stasis both in the device and the LV cavity, 3) minimal blood contacting surface of the pump, 4) easy accessibility with a less invasive surgical procedure, and 5) low cost. A pump flow > 5 L/min was obtained against 100 mmHg differential pressure in the mock circulatory system. The pump could produce a passive pulsatile flow effect with a beating heart more efficiently than other non-pulsatile pumps because of minimal pressure drop and inertia along the bypass tract. Anatomic fit studies using dissected hearts of dilated cardiomyopathy (DCM) cadavers showed that this pump could smoothly pass through the aortic valve without any interference with mitral valve function. Recently, a dynamic pressure groove bearing and a miniature lip seal have been developed. The dynamic pressure groove bearing has a simple structure and acts as a pressure resistant sealing mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Increased cerebral blood flow in preeclampsia with magnetic resonance imaging

    NARCIS (Netherlands)

    Zeeman, GG; Hatab, MR; Twickler, DM

    2004-01-01

    Objective: The purpose of this study was to compare third trimester and nonpregnant cerebral blood flow of women with preeclampsia to normotensive control subjects with the use of magnetic resonance imaging techniques. Study design: Nine normotensive pregnant women and 12 untreated women with preecl

  3. Whole-body vibration dosage alters leg blood flow.

    NARCIS (Netherlands)

    Lythgo, N.; Eser, P.; Groot, P.C.E. de; Galea, M.

    2009-01-01

    The effect of whole-body vibration dosage on leg blood flow was investigated. Nine healthy young adult males completed a set of 14 random vibration and non-vibration exercise bouts whilst squatting on a Galileo 900 plate. Six vibration frequencies ranging from 5 to 30 Hz (5 Hz increments) were used

  4. Splanchnic blood flow and hepatic glucose production in exercising humans

    DEFF Research Database (Denmark)

    Bergeron, R; Kjaer, M; Simonsen, L;

    2001-01-01

    The study examined the implication of the renin-angiotensin system (RAS) in regulation of splanchnic blood flow and glucose production in exercising humans. Subjects cycled for 40 min at 50% maximal O(2) consumption (VO(2 max)) followed by 30 min at 70% VO(2 max) either with [angiotensin...

  5. Age and gender related differences in aortic blood flow

    DEFF Research Database (Denmark)

    Traberg, Marie Sand; Pedersen, Mads Møller; Hemmsen, Martin Christian;

    2012-01-01

    The abdominal aorta (AA) is predisposed to development of abdominal aneurysms (AAA), a focal dilatation of the artery with fatal consequences if left untreated. The blood flow patterns in the AA is thought to play an important role in the development of AAA. The purpose of this work...

  6. Influence of blood flow on the coagulation cascade

    DEFF Research Database (Denmark)

    The influence of diffusion and convetive flows on the blood coagulation cascade is investigated for a controlled perfusion experiment. We present a cartoon model and reaction schemes for parts of the coagulation cascade with sunsequent set up of a mathematical model in two space dimensions plus one...

  7. A VARIATIONAL MODEL FOR 2-D MICROPOLAR BLOOD FLOW

    Institute of Scientific and Technical Information of China (English)

    He Ji-huan

    2003-01-01

    The micropolar fluid model is an essential generalization of the well-established Navier-Stokes model in the sense that it takes into account the microstructure of the fluid.This paper is devolted to establishing a variational principle for 2-D incompressible micropolar blood flow.

  8. Impaired endothelial function and blood flow in repetitive strain injury

    NARCIS (Netherlands)

    Brunnekreef, J.J.; Benda, N.M.M.; Schreuder, T.H.A.; Hopman, M.T.E.; Thijssen, D.H.J.

    2012-01-01

    Repetitive Strain Injury (RSI) is a disabling upper extremity overuse injury that may be associated with pathophysiological changes in the vasculature. In this study we investigated whether RSI is associated with endothelial dysfunction and impaired exercise-induced blood flow in the affected forear

  9. Haemodialysis decreases finger pressures independent of artificial kidney blood flow.

    NARCIS (Netherlands)

    Hoek, F. van; Scheltinga, M.R.M.; Houterman, S.; Beerenhout, C.H.

    2010-01-01

    BACKGROUND: During haemodialysis, some patients experience intensification of symptoms of haemodialysis access-induced distal ischaemia. Aim of this study is to compare the effects of two different regimens of arterial blood flow in patients with an arteriovenous access. METHODS: A questionnaire ide

  10. Cerebral blood flow during static exercise in humans

    DEFF Research Database (Denmark)

    Rogers, H B; Schroeder, T; Secher, N H;

    1990-01-01

    Cerebral blood flow (CBF) was determined in humans at rest and during four consecutive unilateral static contractions of the knee extensors. Each contraction was maintained for 3 min 15 s with the subjects in a semisupine position. The contractions corresponded to 8, 16, 24, and 32% of the maxima...

  11. Longitudinal Cerebral Blood Flow Changes during Speech in Hereditary Ataxia

    Science.gov (United States)

    Sidtis, John J.; Strother, Stephen C.; Naoum, Ansam; Rottenberg, David A.; Gomez, Christopher

    2010-01-01

    The hereditary ataxias constitute a group of degenerative diseases that progress over years or decades. With principal pathology involving the cerebellum, dysarthria is an early feature of many of the ataxias. Positron emission tomography was used to study regional cerebral blood flow changes during speech production over a 21 month period in a…

  12. Cerebral blood flow in patients with dementia of Alzheimer's type

    DEFF Research Database (Denmark)

    Postiglione, A; Lassen, N A; Holman, B L

    1993-01-01

    In the normal brain as well as in Alzheimer's disease (AD), regional cerebral blood flow (CBF) is coupled to metabolic demand and, therefore, changes in CBF reflect variations in neuronal metabolism. The use of radionuclide techniques, such as positron emission tomography (PET) and single photon...

  13. Coded ultrasound for blood flow estimation using subband processing

    DEFF Research Database (Denmark)

    Gran, Fredrik; Udesen, Jesper; Nielsen, Michael bachmann;

    2007-01-01

    This paper further investigates the use of coded excitation for blood flow estimation in medical ultrasound. Traditional autocorrelation estimators use narrow-band excitation signals to provide sufficient signal-to-noise-ratio (SNR) and velocity estimation performance. In this paper, broadband co...

  14. Coded ultrasound for blood flow estimation using subband processing

    DEFF Research Database (Denmark)

    Gran, F.; Udesen, J.; Jensen, J.A.;

    2008-01-01

    This paper investigates the use of coded excitation for blood flow estimation in medical ultrasound. Traditional autocorrelation estimators use narrow-band excitation signals to provide sufficient signal-to-noise-ratio (SNR) and velocity estimation performance. In this paper, broadband coded sign...

  15. Oscillations and chaos in renal blood flow control

    DEFF Research Database (Denmark)

    Holstein-Rathlou, N H

    1993-01-01

    In normotensive, halothane-anesthetized rats, oscillations can be found both in the single-nephron blood flow and in the tubular pressure. Experimental data and computer simulations support the hypothesis that the oscillations are caused by the tubuloglomerular feedback (TGF) mechanism. Model...

  16. Unchanged cerebral blood flow and oxidative metabolism after acclimatization to high altitude

    DEFF Research Database (Denmark)

    Møller, Kirsten; Paulson, Olaf B; Hornbein, Thomas F.;

    2002-01-01

    . Global cerebral blood flow at rest and during exercise on a bicycle ergometer was measured by the Kety-Schmidt technique. Cerebral metabolic rates of oxygen, glucose, and lactate were calculated by the Fick principle. Cerebral function was assessed by a computer-based measurement of reaction time...... and cerebral metabolic rates of oxygen and glucose also remained unchanged, whereas cerebral metabolic rates of lactate increased slightly but nonsignificantly at high altitude during exercise compared with high altitude at rest. Reaction time was unchanged. The data indicate that cerebral blood flow......The authors investigated the effect of acclimatization to high altitude on cerebral blood flow and oxidative metabolism at rest and during exercise. Nine healthy, native sea-level residents were studied 3 weeks after arrival at Chacaltaya, Bolivia (5,260 m) and after reacclimatization to sea level...

  17. Vasodilator interactions in skeletal muscle blood flow regulation

    DEFF Research Database (Denmark)

    Hellsten, Ylva; Nyberg, Michael Permin; Jensen, Lasse Gliemann;

    2012-01-01

    During exercise, oxygen delivery to skeletal muscle is elevated to meet the increased oxygen demand. The increase in blood flow to skeletal muscle is achieved by vasodilators formed locally in the muscle tissue, either on the intraluminal or the extraluminal side of the blood vessels. A number...... vasodilators are both stimulated by several compounds, eg. adenosine, ATP, acetylcholine, bradykinin, and are affected by mechanically induced signals, such as shear stress. NO and prostacyclin have also been shown to interact in a redundant manner where one system can take over when formation of the other...... that this remaining hyperemia may be explained by cAMP and cGMP independent smooth muscle relaxation, such as effects of endothelial derived hyperpolarization factors (EDHFs) or through metabolic modulation of sympathetic effects. The nature and role of EDHF as well as potential novel mechanisms in muscle blood flow...

  18. Results of Pancreatic Blood Shunting into the Systemic Blood Flow in Insulin-Dependent Diabetics

    OpenAIRE

    Galperin, E. I.; Diuzheva, T. G.; Petrovsky, P. F.; A. Yu. Chevokin; Dokuchayev, K. V.; Rabinovich, S. E.; Gitel, E. P.; Kuzovlev, N. F.; Platonov, L. V.

    1996-01-01

    A new surgical method of treating patients with unstable insulin-dependent diabetes (IDD) has been developed-that of surgically shunting pancreatic blood into the systemic blood flow with the purpose of creating a more optimal interaction of subcutaneously administered insulin and pancreas-secreted glucagon. The long term results of the operation depend on the patency of a splenorenal anastomosis. This has been studied by following up 137 patients over periods from half a year to three years....

  19. Epidural blood flow and regression of sensory analgesia during continuous postoperative epidural infusion of bupivacaine

    DEFF Research Database (Denmark)

    Mogensen, T; Højgaard, L; Scott, N B;

    1988-01-01

    Epidural blood flow was measured in seven patients undergoing elective abdominal surgery during combined lumbar epidural and general anesthesia. After an initial dose of 20 ml plain bupivacaine 0.5%, a continuous epidural infusion of bupivacaine 0.5% (8 ml/hr) was given for 16 hours for postopera......Epidural blood flow was measured in seven patients undergoing elective abdominal surgery during combined lumbar epidural and general anesthesia. After an initial dose of 20 ml plain bupivacaine 0.5%, a continuous epidural infusion of bupivacaine 0.5% (8 ml/hr) was given for 16 hours...... surgery, and 8, 12, and 16 hours later during the continuous infusion. Initial blood flow was 6.0 +/- 0.7 ml/min per 100 g tissue (mean +/- SEM). After epidural bupivacaine, blood flow increased in all seven patients to 7.4 +/- 0.7 ml (P less than 0.02). Initial level of sensory analgesia was T4.5 +/- 0...... than 0.03) in the other five patients as the level of sensory analgesia regressed postoperatively. These data suggest that changes in epidural blood flow during continuous epidural infusion of bupivacaine, and thus changes in rates of vascular absorption of bupivacaine from the epidural space, may...

  20. Regional cerebral blood flow during hypoxia-ischemia in immature rats

    Energy Technology Data Exchange (ETDEWEB)

    Vannucci, R.C.; Lyons, D.T.; Vasta, F.

    1988-02-01

    Immature rats subjected to a combination of unilateral common carotid artery ligation and hypoxia sustain brain damage confined largely to the ipsilateral cerebral hemisphere. To ascertain the extent and distribution of ischemic alterations in the brains of these small animals, we modified the Sakurada technique to measure regional cerebral blood flow using carbon-14 autoradiography. Seven-day-old rats underwent right common carotid artery ligation following which they were rendered hypoxic with 8% O2 at 37 degrees C. Before and during hypoxia, the rat pups received an injection of iodo(/sup 14/C)antipyrine for determination of regional cerebral blood flow. Blood flows to individual structures of the ipsilateral cerebral hemisphere were not influenced by arterial occlusion alone; flows to the contralateral hemisphere and to the brainstem and cerebellum actually increased by 25-50%. Hypoxia-ischemia was associated with decreases in regional cerebral blood flow of the ipsilateral hemisphere such that by 2 hours, flows to subcortical white matter, neocortex, striatum, and thalamus were 15, 17, 34, and 41% of control, respectively. The hierarchy of the blood flow reductions correlated closely with the distribution and extent of ischemic neuronal necrosis. However, unlike the pathologic pattern of this model, the degree of ischemia appeared homogeneous within each brain region. Blood flows to contralateral cerebral hemispheric structures were relatively unchanged from prehypoxic values, whereas flows to the brainstem and cerebellum nearly doubled and tripled, respectively. Thus, ischemia is the predominant factor that determines the topography of tissue injury to major regions of immature rat brain, whereas metabolic factors may influence the heterogeneous pattern of damage seen within individual structures.