Academic literature on the topic 'Cerebral transit time'
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Journal articles on the topic "Cerebral transit time"
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Liebetrau, Martin, Jürgen Herzog, Christian U. A. Kloss, Gerhard F. Hamann, and Martin Dichgans. "Prolonged Cerebral Transit Time in CADASIL." Stroke 33, no. 2 (February 2002): 509–12. http://dx.doi.org/10.1161/hs0202.102949.
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Kamano, Hironori, Takashi Yoshiura, Akio Hiwatashi, Koichiro Abe, Osamu Togao, Koji Yamashita, and Hiroshi Honda. "Arterial spin labeling in patients with chronic cerebral artery steno-occlusive disease: Correlation with 15O-PET." Acta Radiologica 54, no. 1 (February 2013): 99–106. http://dx.doi.org/10.1258/ar.2012.120450.
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Background Heterogeneity of arterial transit time due to cerebral artery steno-occlusive lesions hampers accurate regional cerebral blood flow measurement by arterial spin labeling (ASL). Purpose To assess the feasibility of regional cerebral blood flow measurement by ASL with multiple-delay time sampling in patients with steno-occlusive diseases by comparing with positron emission tomography (PET), and to determine whether regional arterial transit time measured by this ASL technique is correlated with regional mean transit time, a PET index of perfusion pressure. Material and Methods Sixteen patients with steno-occlusive diseases received both ASL and 15O-PET. The mean regional cerebral blood flow measured by ASL and PET, regional arterial transit time by ASL, and regional mean transit time by PET were obtained by a region-of-interest analysis. Correlation between regional cerebral blood flow by ASL and that by PET, and correlation between regional arterial transit time by ASL and regional mean transit time by PET were tested using Pearson's correlation coefficient for both absolute and relative values. A multivariate regression analysis was performed to test whether regional arterial transit time by ASL was a significant contributor in modeling regional mean transit time by PET after controlling the effect of regional cerebral blood flow by ASL. Results A significant positive correlation was found between regional cerebral blood flow by ASL and that by PET for both absolute (r = 0.520, P < 0.0001) and relative (r = 0.691, P < 0.0001) values. A significant positive correlation was found between regional arterial transit time by ASL and regional mean transit time by PET both for absolute (r = 0.369, P = 0.0002) and relative (r = 0.443, P < 0.0001) values. The regression analysis revealed that regional arterial transit time by ASL was a significant contributor in modeling regional mean transit time by PET after controlling regional cerebral blood flow by ASL (P = 0.0011). Conclusion The feasibility of regional cerebral blood flow measurement using ASL with multiple-delay time sampling was confirmed in patients with cerebral artery steno-occlusive diseases. Moreover, it was suggested that mapping of regional arterial transit time has the potential to detect hemodynamic impairment.
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Engedal, Thorbjørn S., Niels Hjort, Kristina D. Hougaard, Claus Z. Simonsen, Grethe Andersen, Irene Klærke Mikkelsen, Jens K. Boldsen, et al. "Transit time homogenization in ischemic stroke – A novel biomarker of penumbral microvascular failure?" Journal of Cerebral Blood Flow & Metabolism 38, no. 11 (July 31, 2017): 2006–20. http://dx.doi.org/10.1177/0271678x17721666.
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Cerebral ischemia causes widespread capillary no-flow in animal studies. The extent of microvascular impairment in human stroke, however, is unclear. We examined how acute intra-voxel transit time characteristics and subsequent recanalization affect tissue outcome on follow-up MRI in a historic cohort of 126 acute ischemic stroke patients. Based on perfusion-weighted MRI data, we characterized voxel-wise transit times in terms of their mean transit time (MTT), standard deviation (capillary transit time heterogeneity – CTH), and the CTH:MTT ratio (relative transit time heterogeneity), which is expected to remain constant during changes in perfusion pressure in a microvasculature consisting of passive, compliant vessels. To aid data interpretation, we also developed a computational model that relates graded microvascular failure to changes in these parameters. In perfusion–diffusion mismatch tissue, prolonged mean transit time (>5 seconds) and very low cerebral blood flow (≤6 mL/100 mL/min) was associated with high risk of infarction, largely independent of recanalization status. In the remaining mismatch region, low relative transit time heterogeneity predicted subsequent infarction if recanalization was not achieved. Our model suggested that transit time homogenization represents capillary no-flow. Consistent with this notion, low relative transit time heterogeneity values were associated with lower cerebral blood volume. We speculate that low RTH may represent a novel biomarker of penumbral microvascular failure.
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Arsava, Ethem M., Mikkel B. Hansen, Berkan Kaplan, Ahmet Peker, Rahsan Gocmen, Anil Arat, Kader K. Oguz, Mehmet A. Topcuoglu, Leif Østergaard, and Turgay Dalkara. "The effect of carotid artery stenting on capillary transit time heterogeneity in patients with carotid artery stenosis." European Stroke Journal 3, no. 3 (April 26, 2018): 263–71. http://dx.doi.org/10.1177/2396987318772686.
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Introduction Carotid revascularisation improves haemodynamic compromise in cerebral circulation as an additional benefit to the primary goal of reducing future thromboembolic risk. We determined the effect of carotid artery stenting on cerebral perfusion and oxygenation using a perfusion-weighted MRI algorithm that is based on assessment of capillary transit-time heterogeneity together with other perfusion and metabolism-related metrics. Patients and methods A consecutive series of 33 patients were evaluated by dynamic susceptibility contrast perfusion-weighted MRI prior to and within 24 h of the endovascular procedure. The level of relative change induced by stenting, and relationship of these changes with respect to baseline stenosis degree were analysed. Results Stenting led to significant increase in cerebral blood flow ( p < 0.001), and decrease in cerebral blood volume ( p = 0.001) and mean transit time ( p < 0.001); this was accompanied by reduction in oxygen extraction fraction ( p < 0.001) and capillary transit-time heterogeneity ( p < 0.001), but an overall increase in relative capillary transit-time heterogeneity (RTH: CTH divided by MTT; p = 0.008). No significant change was observed with respect to cerebral metabolic rate of oxygen. The median volume of tissue with MTT > 2s decreased from 24 ml to 12 ml ( p = 0.009), with CTH > 2s from 29 ml to 19 ml ( p = 0.041), and with RTH < 0.9 from 61 ml to 39 ml ( p = 0.037) following stenting. These changes were correlated with the baseline degree of stenosis. Discussion: Stenting improved the moderate stage of haemodynamic compromise at baseline in our cohort. The decreased relative transit-time heterogeneity, which increases following stenting, is probably a reflection of decreased functional capillary density secondary to chronic hypoperfusion induced by the proximal stenosis. Conclusion: Carotid artery stenting, is not only important for prophylaxis of future vascular events, but also is critical for restoration of microvascular function in the cerebral tissue.
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Lo, E. H., J. Rogowska, P. Bogorodzki, M. Trocha, K. Matsumoto, B. Saffran, and G. L. Wolf. "Temporal Correlation Analysis of Penumbral Dynamics in Focal Cerebral Ischemia." Journal of Cerebral Blood Flow & Metabolism 16, no. 1 (January 1996): 60–68. http://dx.doi.org/10.1097/00004647-199601000-00007.
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A novel temporal correlation technique was used to map the first-pass transit of iodinated contrast agents through the brain. Transit profiles after bolus injections were measured with dynamic computed tomography (CT) scanning (1 image/s over 50 s). A rabbit model of focal cerebral ischemia (n = 6) was used, and dynamic CT scans were performed at 30, 60, 90, and 120 min postocclusion. Within the ischemic core, no bolus transit was detectable, demonstrating that complete ischemia was present after arterial occlusion. In the periphery of the ischemic distribution, transit dynamics showed smaller peaks, broadened profiles, and overall delay in bolus transit. A cross-correlation method was used to generate maps of delays in ischemic transit profiles compared with normal transit profiles from the contralateral hemisphere. These maps showed that penumbral regions surrounding the ischemic core had significantly delayed bolus transit profiles. Enlargement of the ischemic core over time (from 30 to 120 min postocclusion) was primarily accomplished by the progressive deterioration of the penumbral regions. These results suggest that (a) temporal correlation methods can define regions of abnormal perfusion in focal cerebral ischemia, (b) peripheral regions of focal cerebral ischemia are characterized by delays in bolus transit profiles, and (c) these regions of bolus transit delay deteriorate over time and thus represent a hemodynamic penumbra.
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Bush, Adam M., Roberta Miyeko Kato, Thomas D. Coates, and John C. Wood. "Cerebral Tissue Transit Time in Patients with Sickle Cell Anemia." Blood 126, no. 23 (December 3, 2015): 280. http://dx.doi.org/10.1182/blood.v126.23.280.280.
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Abstract Introduction Accurate characterization of cerebral blood flow (CBF) in patients with sickle cell anemia (SCA) is imperative given the occurrence of neurovascular sequelae in this population. Arterial Spin Labeling (ASL) is a promising MRI modality that has been used to quantify CBF in SCA by several groups. Unfortunately, ASL quantification has proven challenging in SCA given the unique phenotype found in these patients including decreased hematocrit, elevated blood velocity an abnormal rheologic properties. As a result, there are conflicting accounts of ASL perfusion in this population. One of the key parameters of ASL quantification is the time between the labeling of spins in the neck and the downstream diffusion of those spins into parenchymal tissue, termed tissue transit time (TT). Delayed tissue TT is a known consequence of many neurovascular pathologies, including stroke. Given the elevated cerebral blood velocity and flow in response to anemia, however it is generally assumed that tissue TT is shorter in SCA but has yet to be studied. In order to improve ASL quantification and characterize this neurovascular biomarker we measured ASL derived tissue TT in healthy patients with SCA and ethnicity matched controls. Methods All patients were recruited with informed consent or assent and this study was approved by the Children's Hospital Los Angeles institutional review board. Exclusion criteria included pregnancy, previous stroke, acute chest, pain crisis or hospitalization within one month. All MRI scans were performed on an Achieva 3T scanner with an 8 channel head coil. Tissue TT was measured using two single shot, GRASE, ASL acquisitions, one with velocity spoiling gradients (venc 5 cm/s) and one without. Pseudo continuous ASL had a label duration of 1150ms and delay of 1500ms. Single slice phase contrast MRI of the carotids and vertebral arteries measured arterial blood velocity and global CBF. Hemoglobin level was determined on the day of the study. Results Eight patients with SCA (7 SS, 1 SC; 15.8 + 4.4yo; 5F, 3M) and nine ethnicity matched healthy controls (36.4 + 4.1yo; 6 F, 3M) were recruited. Patients with SCA had a lower hemoglobin levels (SCA, 10.1 + 0.64 g/dl, CTRL 13.7 + 0.58) and elevated CBF (SCA, 76.6 + 5.8 ml/100g/min, CTRL 49.0 + 4.4 ml/100g/min). Regional ASL perfusion asymmetries were observed in several SCA subjects. These asymmetries were not present in corresponding tissue TT maps (Figure 1). There was a trending difference in tissue TT between the two groups (SCA 1588 + 49.8, CTRL 1696 + 46.9 ms, p=.1). After multivariate analysis, sex and global CBF were the only predictors of tissue TT, r2=.54 (Figure 2). Discussion Our data is the first of our knowledge to measure the tissue TT in patients with SCA. Tissue TT is distinct from the bolus arrival time or arterial TT which corresponds to the arrival time of tracer at the imaging region. Tissue transit time is more sensitive to microvascular flow and diffusion effects and may reflect microvascular health and blood brain barrier integrity. Our measurement of tissue TT is congruent with other findings in separate neurovascular pathologies and suggests that gender and global CBF must be considered when quantifying ASL perfusion. These preliminary results also offer insight into the perfusion asymmetries observed in the ASL SCA literature. We found that perfusion asymmetries do not correlate with tissue TT suggesting either 1) tissue TT is conserved despite differences in regional flow or 2) a separate source of error is leading to spurious regional perfusion quantification, ie labeling efficiency. Figure 1. Relative perfusion map (top) vs transit time map (bottom) in a healthy control (left) and patient with SCA (right). Posterior region in healthy control demonstrates longer transit time. Right left perfusion asymmetry in SCA patient is not observed in corresponding transit map. Univariate analysis of sex vs tissue TT (left). Males demonstrate shorter transit time than females. After correcting for gender there is an observed inverse flow effect where larger CBF corresponds to shortened tissue TT (right). Figure 1. Relative perfusion map (top) vs transit time map (bottom) in a healthy control (left) and patient with SCA (right). Posterior region in healthy control demonstrates longer transit time. Right left perfusion asymmetry in SCA patient is not observed in corresponding transit map. / Univariate analysis of sex vs tissue TT (left). Males demonstrate shorter transit time than females. After correcting for gender there is an observed inverse flow effect where larger CBF corresponds to shortened tissue TT (right). Disclosures No relevant conflicts of interest to declare.
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Koch, Klaus Ulrik, Anna Tietze, Joel Aanerud, Gorm von Öettingen, Niels Juul, Jens Christian Hedemann Sørensen, Lone Nikolajsen, Leif Østergaard, and Mads Rasmussen. "Effect of ephedrine and phenylephrine on brain oxygenation and microcirculation in anaesthetised patients with cerebral tumours: study protocol for a randomised controlled trial." BMJ Open 7, no. 11 (November 2017): e018560. http://dx.doi.org/10.1136/bmjopen-2017-018560.
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IntroductionDuring brain tumour surgery, vasopressor drugs are commonly administered to increase mean arterial blood pressure with the aim of maintaining sufficient cerebral perfusion pressure. Studies of the commonly used vasopressors show that brain oxygen saturation is reduced after phenylephrine administration, but unaltered by ephedrine administration. These findings may be explained by different effects of phenylephrine and ephedrine on the cerebral microcirculation, in particular the capillary transit-time heterogeneity, which determines oxygen extraction efficacy. We hypothesised that phenylephrine is associated with an increase in capillary transit-time heterogeneity and a reduction in cerebral metabolic rate of oxygen compared with ephedrine. Using MRI and positron emission tomography (PET) as measurements in anaesthetised patients with brain tumours, this study will examine whether phenylephrine administration elevates capillary transit-time heterogeneity more than ephedrine, thereby reducing brain oxygenation.Methods and analysisThis is a double-blind, randomised clinical trial including 48 patients scheduled for surgical brain tumour removal. Prior to imaging and surgery, anaesthetised patients will be randomised to receive either phenylephrine or ephedrine infusion until mean arterial blood pressure increases to above 60 mm Hg or 20% above baseline. Twenty-four patients were allocated to MRI and another 24 patients to PET examination. MRI measurements include cerebral blood flow, capillary transit-time heterogeneity, cerebral blood volume, blood mean transit time, and calculated oxygen extraction fraction and cerebral metabolic rate of oxygen for negligible tissue oxygen extraction. PET measurements include cerebral metabolic rate of oxygen, cerebral blood flow and oxygen extraction fraction. Surgery is initiated after MRI/PET measurements and subdural intracranial pressure is measured.Ethics and disseminationThis study was approved by the Central Denmark Region Committee on Health Research Ethics (12 June 2015; 1-10-72-116-15). Results will be disseminated via peer-reviewed publication and presentation at international conferences.Trial registration numberNCT02713087; Pre-results. 2015-001359-60; Pre-results.
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Alsop, D. C., and J. A. Detre. "Reduced Transit-Time Sensitivity in Noninvasive Magnetic Resonance Imaging of Human Cerebral Blood Flow." Journal of Cerebral Blood Flow & Metabolism 16, no. 6 (November 1996): 1236–49. http://dx.doi.org/10.1097/00004647-199611000-00019.
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Herein, we present a theoretical framework and experimental methods to more accurately account for transit effects in quantitative human perfusion imaging using endogenous magnetic resonance imaging (MRI) contrast. The theoretical transit time sensitivities of both continuous and pulsed inversion spin tagging experiments are demonstrated. We propose introducing a delay following continuous labeling, and demonstrate theoretically that introduction of a delay dramatically reduces the transit time sensitivity of perfusion imaging. The effects of magnetization transfer saturation on this modified continuous labeling experiment are also derived, and the assumption that the perfusion signal resides entirely within tissue rather than the arterial microvasculature is examined. We present results demonstrating the implementation of the continuous tagging experiment with delay on an echoplanar scanner for measuring cerebral blood flow (CBF) in normal volunteers. By varying the delay, we estimate transit times in the arterial system, values that are necessary for assessing the accuracy of our quantification. The effect of uncertainties in the transit time from the tagging plane to the arterial microvasculature and the transit time to the tissue itself on the accuracy of perfusion quantification is discussed and found to be small in gray matter but still potentially significant in white matter. A novel method for measuring T1, which is fast, insensitive to contamination by cerebrospinal fluid, and compatible with the application of magnetization transfer saturation, is also presented. The methods are combined to produce quantitative maps of resting and hypercarbic CBF.
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Kamp, Marcel A., Philipp Slotty, Bernd Turowski, Nima Etminan, Hans-Jakob Steiger, Daniel Hänggi, and Walter Stummer. "Microscope-Integrated Quantitative Analysis of Intraoperative Indocyanine Green Fluorescence Angiography for Blood Flow Assessment: First Experience in 30 Patients." Operative Neurosurgery 70, suppl_1 (August 1, 2011): ons65—ons74. http://dx.doi.org/10.1227/neu.0b013e31822f7d7c.
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Abstract BACKGROUND: Intraoperative measurements of cerebral blood flow are of interest during vascular neurosurgery. Near-infrared indocyanine green (ICG) fluorescence angiography was introduced for visualizing vessel patency intraoperatively. However, quantitative information has not been available. OBJECTIVE: To report our experience with a microscope with an integrated dynamic ICG fluorescence analysis system supplying semiquantitative information on blood flow. METHODS: We recorded ICG fluorescence curves of cortex and cerebral vessels using software integrated into the surgical microscope (Flow 800 software; Zeiss Pentero) in 30 patients undergoing surgery for different pathologies. The following hemodynamic parameters were assessed: maximum intensity, rise time, time to peak, time to half-maximal fluorescence, cerebral blood flow index, and transit times from arteries to cortex. RESULTS: For patients without obvious perfusion deficit, maximum fluorescence intensity was 177.7 arbitrary intensity units (AIs; 5-mg ICG bolus), mean rise time was 5.2 seconds (range, 2.9-8.2 seconds; SD, 1.3 seconds), mean time to peak was 9.4 seconds (range, 4.9-15.2 seconds; SD, 2.5 seconds), mean cerebral blood flow index was 38.6 AI/s (range, 13.5-180.6 AI/s; SD, 36.9 seconds), and mean transit time was 1.5 seconds (range, 360 milliseconds-3 seconds; SD, 0.73 seconds). For 3 patients with impaired cerebral perfusion, time to peak, rise time, and transit time between arteries and cortex were markedly prolonged (>20, >9 , and >5 seconds). In single patients, the degree of perfusion impairment could be quantified by the cerebral blood flow index ratios between normal and ischemic tissue. Transit times also reflected blood flow perturbations in arteriovenous fistulas. CONCLUSION: Quantification of ICG-based fluorescence angiography appears to be useful for intraoperative monitoring of arterial patency and regional cerebral blood flow.
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Elting, Jan Willem J., Jeanette Tas, Marcel JH Aries, Marek Czosnyka, and Natasha M. Maurits. "Dynamic cerebral autoregulation estimates derived from near infrared spectroscopy and transcranial Doppler are similar after correction for transit time and blood flow and blood volume oscillations." Journal of Cerebral Blood Flow & Metabolism 40, no. 1 (October 24, 2018): 135–49. http://dx.doi.org/10.1177/0271678x18806107.
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We analysed mean arterial blood pressure, cerebral blood flow velocity, oxygenated haemoglobin and deoxygenated haemoglobin signals to estimate dynamic cerebral autoregulation. We compared macrovascular (mean arterial blood pressure-cerebral blood flow velocity) and microvascular (oxygenated haemoglobin-deoxygenated haemoglobin) dynamic cerebral autoregulation estimates during three different conditions: rest, mild hypocapnia and hypercapnia. Microvascular dynamic cerebral autoregulation estimates were created by introducing the constant time lag plus constant phase shift model, which enables correction for transit time, blood flow and blood volume oscillations (TT-BF/BV correction). After TT-BF/BV correction, a significant agreement between mean arterial blood pressure-cerebral blood flow velocity and oxygenated haemoglobin-deoxygenated haemoglobin phase differences in the low frequency band was found during rest (left: intraclass correlation=0.6, median phase difference 29.5° vs. 30.7°, right: intraclass correlation=0.56, median phase difference 32.6° vs. 39.8°) and mild hypocapnia (left: intraclass correlation=0.73, median phase difference 48.6° vs. 43.3°, right: intraclass correlation=0.70, median phase difference 52.1° vs. 61.8°). During hypercapnia, the mean transit time decreased and blood volume oscillations became much more prominent, except for very low frequencies. The transit time related to blood flow oscillations was remarkably stable during all conditions. We conclude that non-invasive microvascular dynamic cerebral autoregulation estimates are similar to macrovascular dynamic cerebral autoregulation estimates, after TT-BF/BV correction is applied. These findings may increase the feasibility of non-invasive continuous autoregulation monitoring and guided therapy in clinical situations.
Dissertations / Theses on the topic "Cerebral transit time"
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Naylor, A. Ross. "Evaluation and clinical application of a new method of quantifying mean cerebral transit time." Thesis, University of Aberdeen, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240668.
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Recent work using Positron Emission Tomography has indicated that the best indicator of cerebral vascular reserve (CVR) is the ratio of cerebral blood flow to cerebral blood volume, which is the reciprocal of mean cerebral transit time (MCTT). However, previous attempts to quantify MCTT have ben unsuccessful. A new isotopic method of quantifying MCTT, which has overcome previous problems, is described and has been subjected to validation and application in two studies: (i) in patients with acute stroke, (ii) in patients undergoing carotid endarterectomy. In the validation study, MCTT was compared with blood flow velocity in the middle cerebral artery, using Transcranial Doppler (TCD) sonography. Both methods were reproducible and there was a linear relationship between MCTT and inter-hemispheric MCTT asymmetry has been defined. The transit time and TCD methods were employed in 32 patients with acute, first-time cerebral infarction. Patterns of underlying vascular pathology correlated with a clinical and CT scan/autopsy classification of cerebral infarction and there was good correlation between the transit time and TCD findings. The new technique, when applied to 55 patients undergoing carotid endarterectomy, showed that 31% had pre-operative evidence of impaired CVR in the symptomatic hemisphere, 75% returning to normal after surgery. Significant predictors for intra-operative sroke were; (i) age over 65, (ii) residual neurological deficit, (iii) complex plaque morphology, (iv) the combination of impaired CVR and CT infarction in the symptomatic hemisphere. No patient with recurrent symptoms after carotid endarterectomy has developed impaired CVR or recurrent disease in the operated internal carotid artery (ICA) during follow-up. One patient has developed impaired CVR in the non-operated hemisphere in association with disease progression in the non-operated ICA. The transit time method shows considerable potential as an inexpensive, quick and simple alternative to the previously available methods of evaluating CVR.
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Schmid, Benedikt [Verfasser], and Wolfgang [Akademischer Betreuer] Müllges. "Relation between cerebral arterio-venous transit time and neuropsychological performance in patients with vascular dementia / Benedikt Schmid. Betreuer: Wolfgang Müllges." Würzburg : Universität Würzburg, 2013. http://d-nb.info/1102820040/34.
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Grieser, Christian. "Erkennung zerebraler Ischämie mittels computertomographischer Perfusionskartographie und CT-Angiographie." Doctoral thesis, Humboldt-Universität zu Berlin, Medizinische Fakultät - Universitätsklinikum Charité, 2006. http://dx.doi.org/10.18452/15429.
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Zielsetzung In den Industrieländern stellt der Schlaganfall nach kardiovaskulären und Krebs – erkrankungen die dritthäufigste Krankheitsgruppe dar. Im Hinblick auf die Therapie des akuten Schlaganfalls muss die bildgebende Diagnostik schnell und einfach das Ausmaß der zerebralen Ischämie beschreiben können. Ziel dieser Studie war die Einführung und die Validierung eines CT – Protokolls, welches die Diagnostik des akuten Schlaganfalls verbessern soll. Zu diesem CT – Protokoll gehören ein Nativ – CT des Schädels, eine CT – Perfusionsuntersuchung und eine CT – Angiographie. Zusätzlich wollte diese Arbeit herausfinden, ob es physiologische Unterschiede zwischen der grauen Substanz und der weißen Substanz gibt, deren Kenntnis entscheidend für die Auswertung von computertomographischen Perfusionsuntersuchungen sind. Material und Methoden Insgesamt wurden 101 Patienten (Alter von 14 – 94 Jahre, mittleres Alter 69 Jahre) mit einem 8 – bzw. 16 – Zeilen – MSCT (Light Speed Ultra oder Light Speed pro 16, GE Healthcare), die zur Abklärung einer zerebralen Ischämie zum CT vorgestellt wurden, untersucht. Zuerst wurde eine native CT – Serie akquiriert. In der Untersuchung der zerebralen Perfusion wurde eine 2 cm breite Schicht über 60 sec mit 20 intermittierenden Aufnahmen während einer Injektion von 40 ml Kontrastmittel (Iopromid, Jodgehalt von 370 mg) aufgezeichnet. Daran an schloss sich eine CT – Angiographie Untersuchung. Zur Bestimmung des regionalen zerebralen Blutflusses, des regionalen zerebralen Blutvolumens und der mittleren Verweildauer wurden definierte Messfelder (Regions of Interests, ROIs) bestimmt und mit der kontralateralen Hemisphäre verglichen. Ergebnisse Es konnte gezeigt werden, dass der regionale zerebrale Blutfluss und das Blutvolumen im Bereich der Hirnrinde höher sind als im Hirnmark. Insgesamt wurden 66 Patienten mit einer zerebralen Ischämie wurden gefunden. Bei 22 dieser Patienten konnte ein Infarktgeschehen in der Nativ – CT diagnostiziert werden. Diese Ischämien ließen sich auch in der CT – Perfusion mit reduziertem regionalem zerebralem Blutfluss und verlängerter mittlerer Verweildauer nachweisen. Zusätzlich fanden sich 44 Patienten von 101 Untersuchten, die in der CT – Perfusion ein Perfusionsdefizit aufwiesen. Bei diesen Patienten ließ sich kein entsprechendes Korrelat in der Nativ – CT nachweisen. Für 38 dieser 44 Patienten konnte eine CTA durchgeführt werden, wovon für 35 Patienten ein Korrelat zwischen der CT – Perfusion und der CTA gefunden werden konnte. Schlussfolgerung Die Ergebnisse dieser Arbeit zeigen, dass es physiologische Unterschiede zwischen der Hirnrinde und dem Hirnmark gibt, deren Kenntnis für die Bewertung computertomographischer Perfusionsuntersuchungen eine wesentliche Interpretationshilfe darstellt. In Bezug auf die Diagnostik des akuten Schlaganfalls mit der Nativ – CT konnte diese Arbeit zeigen, dass der Nachweis von Infarktfrühzeichen eingeschränkt ist. Mit Hilfe der CT – Perfusion ist es möglich, anhand von zerebralen Perfusionswerten den Schweregrad und die Ausdehnung der zerebralen Ischämie zu bestimmen. Die CT – Angiographie zeigt eine gute Korrelation zur CT – Perfusion, es lassen sich zuverlässig Gefäßverschlüsse darstellen. Im Hinblick auf das weitere Therapievorgehen geben diese Methoden eine wichtige Hilfestellung, etwa zur Überlegung, ob man eine Lysetherapie durchführen sollte oder nicht.Purpose Stroke is the third – leading cause of death in developed countries, following cardiovascular disease and cancer. There is a need for an easily and rapidly performed technique to detect cerebral ischemia in the first hours after its occurrence. The purpose of this study was the introduction and validation of a Stroke protocol which includes an unenhanced CT scan, a CT Perfusion and a CT Angiography. Furthermore, the purpose of this study was to determine if there is a difference between Perfusion parameters in gray and white matter, which are necessary to know while performing perfusion maps. Data and Methodology A total of 101 patients (age range 14 – 94, average age 69 years) were examined using multiple row CT (8 / 16 row multiple detector, light ultra speed or light speed 16, GE medical systems) for diagnosing cerebral ischemia. First a series of native images was acquired. During the examination of cerebral perfusion a 2 cm wide slab was recorded for 60 sec with 20 intermittent scans following injection of 40 ml of contrast medium with an iodine content of 370 mg / ml. By defining Regions of Interests (ROIs) regional cerebral blood flow (CBF), regional cerebral blood volume (CBV) and mean transit time (MTT) were calculated. Results Physiological regional cerebral blood flow and cerebral blood volume in gray matter were higher than in white matter. In total 66 patients with a cerebral ischemia were found. The unenhanced CT detected 22 patients with cerebral ischemia, which were confirmed by CT Perfusion in all cases. These ischemic areas revealed reduced regional CBF and extended MTT. Furthermore an ischemia correlative was discovered by perfusion analysis for 44 patients (out of 101 investigated) where the extent of the cerebral ischemia had not been visible by unenhanced CT. For 38 out of 44 patients with cerebral ischemia we were able to perform a CTA. For 35 out of these 38 patients, we found a sizable correlation between perfusion maps and CTA. Conclusion There are physiological differences for CT Perfusion parameters between gray and white matter, which are necessary to know for the interpretation of perfusion maps. However, this examination was able to show that unenhanced CT is not always capable of showing early CT signs. With the help of CT perfusion it is possible to detect the extent of acute cerebral ischemia. Furthermore, CT Angiography shows a sizable correlation compared to CT Perfusion. In conjunction, these methods give important Information for the early diagnosis and the therapeutic strategy of ischemic brain injury.
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Schmid, Benedikt. "Relation between cerebral arterio-venous transit time and neuropsychological performance in patients with vascular dementia." Doctoral thesis, 2012. https://nbn-resolving.org/urn:nbn:de:bvb:20-opus-71234.
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Dementia, or any form of degenerative cognitive decline, is one of the major problems in present, and even more will be in future medicine. With Alzheimer's disease (AD) being the most prevalent, Vascular Dementia is the second most entity of dementing processes in the elderly. As diagnostic criteria are still imprecise and in many cases do not embrace early stages of the disease, recent studies have proposed more detailed classifications of the newly created condition Vascular Cognitive Impairment (VCI). Of all conditions subsumed under this term, subcortical small-vessel alterations are the most common cause for cognitive decline. The diagnosis of dementia / cognitive impairment is presently often made in late stages of the disease, when therapeutical options are poor. Thus, early detection of changes of the subcortical small vessels is desirable, when there is still time to identify and aggressively treat risk factors and underlying conditions like diabetes, hyper- or hypotension, and hyperlipidemia. This study aimed to evaluate whether cTT correlates to cognitive dysfunction, i.e. if cTT is fit as an early diagnostic tool for VCI. The study cohort included 38 patients from the Neurological Clinic of the Würzburg University hospital admitted due to diagnoses other than dementia or stroke. As a result of this study it turned out that cTT is certainly capable of fulfilling the task to easily and effectively detect and evaluate possible microvascular lesions of the brain with respect to the actual clinical relevance for the patient. When compared to the other proposed diagnostic tools, neuropsychological testing and MRI, the advantages of cTT are obvious: its measurement is a low-cost and quick procedure which would spare both patients and examiners a long neuropsychological exam or complement it. cTT is safe to assess as the only possible risks derive from the use of the contrast agent, which are rare and easily manageable. It has also proven to be more accurate in showing the extent of cognitive impairment than MRI. Finally, it is widely available. The only prerequisite is an ultrasound machine capable of transcranial color-coded duplex sonography. No cost-intensive procedures like MRI are needed. So, with neuropsychological testing remaining the gold standard, cTT here proved to be a reliable alternative which is more time- and cost-effective than MRIDemenzen und alle anderen Formen kongnitiver Leistungseinschränkungen gehören heute zu den bedeutendsten medizinischen Herausforderungen und werden in der Zukunft noch weiter an Bedeutung gewinnen. Die häufigste der Demenzerkrankungen bei älteren Patienten ist die Alzheimer-Krankheit, gefolgt von den vaskulären Demenzen. Da die Diagnosekriterien in vielen Fällen noch unpräzise sind und vor allem frühe Stadien der Erkrankung nicht erfassen, wurden in der neueren Literatur detailliertere Untergruppen der neu eingeführten Entität „vaskuläre kognitive Funktionsstörung“ (vascular cognitive impairment, VCI) etabliert. Subkortikale Veränderungen an den kleinsten Gefäßen stellen unter allen Pathologien, die unter diesem Begriff subsumiert sind, die häufigste Ursache für kognitive Leistungseinschränkungen dar. Die Diagnose Demenz bzw. VCI wird oft erst in späten Stadien der Krankheit gestellt, wenn die therapeutischen Mittel bereits stark begrenzt sind. Deshalb wäre eine Möglichkeit zur frühen Entdeckung subkortikaler Gefäßveränderungen wünschenswert in einem Stadium der Krankheit, in dem es noch möglich ist, Risikofaktoren wie Diabetes mellitus, arterielle Hyper- und Hypotonie und Fettstoffwechselstörungen auszumachen und konseqeuent zu behandeln. Das Ziel dieser Studie war es zu untersuchen, ob cTT mit dem Ausmaß kognitiver Dysfunktion korreliert, ob also cTT als frühes diagnostisches Verfahren für vaskuläre demenzielle Prozesse geeignet ist. Die Studienpopulation umfasste 38 Patienten aus der Klinik und Poliklinik für Neurologie der Universität Würzburg. Ein Ergebnis dieser Studie ist, dass die cTT sicherlich in der Lage ist, einfach und zuverlässig mögliche mikrovaskuläre Schädigungen des Gehirns auch im Hinblick auf ihre tatsächliche klinische Relevanz zu entdecken. Im Vergleich mit anderen Diagnoseverfahren (Testpsychologie und MRT) sind die Vorteile der cTT offensichtlich: die Messung ist ein kostengünstiges und schnelles Verfahren, das sowohl Patienten als auch Untersuchern eine langwierige neuropsychologische Untersuchung erspart. Die Messung der cTT ist ein sicheres Verfahren, da die wenigen aus der Anwendung des Kontrastmittels sich ergebenden Risiken selten und gegebenenfalls leicht behandelbar sind. Zudem erwies sich die cTT als präziser bei der Aufgabe, das Ausmaß kognitiver Dysfunktion zu messen, als es die MRT vermochte. Zuletzt ist die cTT auch flächendeckend verfügbar. Die einzige Voraussetzung ist ein Duplex-fähiges Ultraschallgerät. Kostenintesive Untersuchungen wie die MRT können vermieden werden. Wenn auch die Testpsychologie der Goldstandard bleiben wird, erwies sich die cTT als zuverlässige Alternative die im Vergleich zur MRT sowohl Zeit als auch Kosten spart
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Chen, Yi-Ju, and 陳薏茹. "Evaluation of different Postprocessing Methods for Determination of Cerebral Blood Flow and Mean Transit Time by MR Perfusion Imaging." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/47895569854908277715.
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碩士國立陽明大學
生物醫學影像暨放射科學系暨研究所
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Dynamic susceptibility contrast magnetic resonance imaging is a technique for measuring cerebral blood perfusion. Quantitative calculations on the hemodynamic parameters such as cerebral blood volume ( CBV ) 、 cerebral blood flow ( CBF ) 、and mean transit time ( MTT ) are used for the diagnosis of cerebral vascular diseases, such as stenosis and acute ischemic stroke. Computer simulation was used to evaluate the effect of tracer delay on the quantification of CBF and MTT using different calculation techniques, including ： Maximum slope、Maximum concentration、Fourier transform、standard singular value decomposition ( sSVD ), and circular singular value decomposition ( cSVD ). Scatter plots were used to evaluate parameters calculated for different tissues using these algorithms from clinical images in patients with stenosis. The four tissue types determined from the independent component analysis segmentation were artery on the normal and stenosis sides, and brain parenchyma on the normal and stenosis sides. Our simulation results indicate that：1) CBF were underestimated for short MTTs in all calculation techniques；2) sSVD is sensitive to tracer time delay；3) MTT_sSVD may provide high contrast for clinical diagnosis；4) CBF and MTT calculated by Maximum slope and Maximum concentration algorithms are similar to cSVD. The Maximum concentration algorithm is not only less sensitive to noise, but also easy to calculate without any complicated calculation. Scatter plot analysis of clinical images indicate that：1) the CBF_sSVD values for artery and brain parenchyma at the normal side were higher than CBF_cSVD values； 2) the MTT _sSVD values for artery and brain parenchyma at the abnormal side were longer than MTT _cSVD values； 3) MTT _sSVD may provide high contrast for clinical images in patients with stenosis.
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Chaudhary, Simone. "Characterization of the Hemodynamic Profile of Early Alzheimer's Disease via Arterial Spin Labeling Magnetic Resonance Imaging." Thesis, 2012. http://hdl.handle.net/1807/32232.
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Arterial spin labeling is a completely non-invasive method for blood-flow measurement techniques. Alzheimer's disease pathology includes microvascular abnormalities in addition to practically all risk factors having a vascular component that reduces cerebral perfusion. Hemodynamic parameters of cerebral blood flow and arterial transit time were estimated via single-compartment modeling of pseudo continuous arterial spin labeling data and neurocognitive test scores (Alzheimer's disease assessment scale and mini-mental state examination) were compared between a group of healthy (N=20) and early Alzheimer's disease (N=25) subjects before and six months after the Alzheimer's subjects began treatment with cholinesterase inhibitors. The early Alzheimer's group showed improved CBF after 6 months' treatment in every Alzheimer's-prone region except the medial and lateral temporal lobes. No difference in arterial transit time was found between groups, indicating that the pathophysiological process causing hypoperfusion in Alzheimer's disease may differ from vascular dementia.
Books on the topic "Cerebral transit time"
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Haunton, Victoria, Aung Sett, Amit Mistri, and Martin Fotherby. Stroke. Edited by Patrick Davey and David Sprigings. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780199568741.003.0227.
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The World Health Organization defines stroke as ‘a clinical syndrome consisting of rapidly developing clinical signs of focal (at times global) disturbance of cerebral function lasting greater than 24 hours (or leading to death) with no apparent cause other than that of vascular origin’. Transient ischaemic attack (TIA) is defined as a rapid presentation of neurological deficit with complete recovery within 24 hours of the onset of symptoms. However, the 24-hour cut-off is arbitrary, has no biological basis, and is of limited use clinically. A shorter duration is now regarded as more appropriate, although it has yet to be universally accepted. In clinical practice, stroke and TIA are best thought of as comprising a continuum, as they have similar pathological mechanisms, etiologies, and management strategies. While subarachnoid haemorrhage is a type of stroke based on the above definition, it is not covered in this chapter, as its pathophysiology, clinical manifestations, and management are distinct from those for ischaemic stroke and haemorrhagic stroke.
Book chapters on the topic "Cerebral transit time"
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Minns, R. A., and M. V. Merrick. "Cerebral Perfusion Pressure and Nett Cerebral Mean Transit Time in Childhood Hydrocephalus." In Annual Review of Hydrocephalus, 25–26. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-662-11158-1_15.
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LaManna, J. C., and R. P. Shockley. "Determination of Cerebral Cortical Capillary Blood Volume from Mean Transit Time Analysis." In Oxygen Transport to Tissue IX, 29–34. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4684-7433-6_4.
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Szarmach, Arkadiusz, Marta A. Małkiewicz, Agata Zdun-Ryżewska, Grzegorz Halena, Marek Radkowski, Jarosław Dzierżanowski, Kamil Chwojnicki, et al. "Relative Cerebral Blood Transit Time Decline and Neurological Improvement in Patients After Internal Carotid Artery Stenting." In Advances in Experimental Medicine and Biology, 71–80. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/5584_2019_378.
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Ferrari, Marco, David A. Wilson, Daniel F. Hanley, and Richard J. Traystman. "Near Infrared Determined Cerebral Transit Time and Oxy- and Deoxyhemoglobin Relationships During Hemorrhagic Hypotension in the Dog." In Oxygen Transport to Tissue XI, 55–62. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4684-5643-1_7.
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Wolf, M., H. U. Bucher, M. Keel, K. von Siebenthal, and G. Duc. "Estimation of Cerebral Blood Volume and Transit Time in Neonates From Quick Oxygen Increases Measured by Near-Infrared Spectrophotometry." In Advances in Experimental Medicine and Biology, 93–99. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-1-4613-0333-6_11.
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Mies, Günter, and Behrouz Momeni. "Preconditioning of Gerbil Brain Reduces Hippocampal Depolarization Time Following Transient Forebrain Ischemia: Relationship to Hippocampal CA1 Neuron Injury." In Maturation Phenomenon in Cerebral Ischemia V, 265–73. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-642-18713-1_26.
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Kuroiwa, T., I. Yamada, Y. Hakamata, K. Ohno, S. Endo, I. Nakano, and U. Ito. "Time Course of Postischemic Stroke Symptoms and Delayed Infarction After Transient Cerebral Ischemia in Gerbils: Effect of Chemical Preconditioning Using 3-Nitropropionic Acid." In Maturation Phenomenon in Cerebral Ischemia IV, 141–45. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-59446-5_17.
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Bertoldo, Alessandra, Francesca Zanderigo, and Claudio Cobelli. "Assessment of Cerebral Blood Flow, Volume, and Mean Transit Time from Bolus-Tracking MRI Images." In Signal Processing and Communications, 587–604. CRC Press, 2005. http://dx.doi.org/10.1201/9781420028669.ch19.
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Larner, A. J. "Syncope." In Oxford Textbook of Medicine, 4838–41. Oxford University Press, 2010. http://dx.doi.org/10.1093/med/9780199204854.003.240504_update_001.
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Syncope is the commonest identified cause of transient loss of consciousness, being ten times more frequent than epilepsy. It is a consequence of cerebral underperfusion due to reduced cardiac output, often related to reduced venous return due to decreased peripheral vascular resistance, with pooling of blood volume in dependent body parts....
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Duvall, Jaclyn R., and Jerry W. Swanson. "A Man With Recurrent Headache and Focal Neurologic Deficits." In Mayo Clinic Cases in Neuroimmunology, edited by Andrew McKeon, B. Mark Keegan, and W. Oliver Tobin, 222–24. Oxford University Press, 2021. http://dx.doi.org/10.1093/med/9780197583425.003.0072.
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A 42-year-old healthy man sought care for transient episodes of neurologic deficits followed by severe headache. The first episode began with left hand weakness, numbness, and dysarthria, followed approximately 1 hour later by a right temporal headache. His symptoms spontaneously resolved after 8 hours. He had a second episode 2 days later manifested by confusion and bilateral lower extremity numbness, again followed by severe headache with symptoms resolving within 12 hours. A total of 8 episodes occurred over 3 weeks, each lasting 8 to 24 hours, with spontaneous resolution each time. His most recent episode occurred during cerebral angiography. Cerebrospinal fluid evaluation showed opening pressure, 190 mm H2O; white blood cells, 205/μL, 97% lymphocytes; protein, 95 mg/dL; and glucose, 40 mg/dL. Electroencephalography demonstrated right greater than left generalized slowing, with increased-voltage rhythmic delta wave activity, in the frontal regions predominantly. Conventional cerebral angiography findings were normal, but the test appeared to provoke the patient’s previous episode. Neurologic examination was normal after his most recent episode resolved, and no further episodes were reported. This case highlights a typical presentation of transient headache and neurologic deficits with cerebrospinal fluid lymphocytosis. Because the disorder was self-limited, treatment was aimed at symptomatic management of headache. In this case patient with a secure diagnosis of headache and neurologic deficits with cerebrospinal fluid lymphocytosis and stereotypical episodes limited to 3 months after the initial presentation, additional testing was not indicated. Headache and neurologic deficits with cerebrospinal fluid lymphocytosis is a rare, self-limited, benign condition with migrainelike headache episodes accompanied by transient neurologic deficits usually lasting more than 4 hours, with some deficits lasting more than 24 hours.
Conference papers on the topic "Cerebral transit time"
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Sadasivan, Chander, Liliana Cesar, and Baruch B. Lieber. "Mixing of Angiographic Contrast With Blood During Injections in the Cerebral Circulation." In ASME 2008 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2008. http://dx.doi.org/10.1115/sbc2008-192336.
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In the past, various techniques such as indicator dilution, transit time, parametric imaging, or first-pass distribution have been used to estimate blood flow rates during angiographic contrast injections. We have previously employed the method of modeling contrast concentration curves to assess changes in flow exchange between parent cerebral vessels and cerebral aneurysms due to endovascular treatment by flow divertors [1]. There has been concern, however, that contrast injected under such situations may remain as a separate slug or stream flowing with blood or that contrast may settle from blood in the direction of gravity due to its higher density [2,3]. According to this argument, therefore, the analysis of the transport of angiographic contrast visualized under X-ray cannot be used to represent the transport of blood.
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Lee, Gija, Seokkeun Choi, Sungwook Kang, Samjin Choi, Jeonghoon Park, Dong Hyun Park, Youngho Park, Kyungsook Kim, Bermseok Oh, and Hunkuk Park. "Changes in Extracellular Glutamate Release on Repetitive Transient Occlusion in Global Ischemia Model." In ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-206602.
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During the operation, surgeons in neurosurgical area usually performed the multiple temporary occlusions of parental artery which may induce the neuronal damage. It is generally thought that neuronal damage by cerebral ischemia is associated with extracellular concentrations of the excitatory amino acids. In this experiment, we measured the dynamics of extracellular glutamate release in 11 vessel occlusion (VO) model during repeated within short interval. Changes in cerebral blood flow were monitored by laser-Doppler flowmetry simultaneously with cortical glutamate level measured by amperometric biosensor. During ischemia, the peak level of glutamate release was gradually decreased as 112.38±26.21 μM in first period, 82.63±18.50 μM in second period, and 48.58±11.89 μM in third period. The time interval between the ischemia induction and the beginning of glutamate release was increased as 106.7 ± 10.89 (sec) at first attack, 139.11 ± 3.87 (sec) in second attack, 169.00 ± 14.56 (sec) in third ischemic period. From the results of real-time monitoring about glutamate release in 11-VO model during repetitive ischemic episode, it was demonstrated that repetitive ischemia induced less glutamate release from neuronal cell than single ischemia due to endogeneous protective mechanism which delayed glutamate release time in later ischemic injury.
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Strano, A., G. Davi, I. Catalano, G. Francavilla, and A. Notarbartolo. "IS BETATHROMBOGLOBULIN (BTG) OF PROGNOSTIC VALUE IN PATIENTS WITH TRANSIENT CEREBRAL ISCHEMIA (TIA) ?" In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643055.
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TIA and stroke have for a long time been recognized as being associated with various abnormalities in platelet function.Plasma levels of BTG, a marker of platelet release reaction, have been found raised in TIA patients. However plasma measurements can be influenced by venipuncture or handling of the samples Therefore we measured urinary BTG levels and compared plasma and urinary levels of this protein in 18 patients with TIA and 18 controls of equivalent age (41-68 years) and sex.Plasma BTG levels were not different between TIA subjects (24.1 ± 8.6 ng/ml) and controls (20.2 ± 6.4 ng/ml). Urinary BTG levels were significantly different between TIA patients (0.72 ± 0.24 ng/ml) and controls (0.28 ± 0.09 ng/ml) and platelets from TIA patients were more sensitive to ADP than those from controls.After 6 months of ticlopidine administration urinary BTG levels in TIA patients fell to within normal ranges, plasma BTG values remained in the normal range and the the AC50 for ADP was significantly increased.We conclude that only urinary BTG levels may have diagnostic usefulness to evaluate a slight but continous platelet activation of circulating platelets, for istance, by ulcerated plaques in cranial arteries. The interpretation of elevated plasma BTG levels is hampered by the influence of the blood sampling technique which may give rise to false high levels due to platelet release during or after blood sampling. Urinary BTG levels provide a means for following the effects of therapy.In 4 patients,in whom ischemic attacks occured during the course of treatment, urinary and plasma BTG were not higher than in subjects in whom no further events occured. Therefore our data suggest that measurements of urinary and plasma BTG values have no prognostic value in TIA patients.
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Lieber, B. B., A. K. Wakhloo, A. Divani, and S. Rudin. "Determination of Vascular Geometry and Flow Velocity in Cerebral Arteriovenous Malformations (AVMs) Using Double Contrast and High-Speed Digital Subtraction Angiography." In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0027.
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Abstract Successful therapeutic embolization, i.e., catheter-based occlusion of cerebral arteriovenous malformations (AVMs) using liquid embolic agents requires precise knowledge of highly variant AVM architecture, blood flow velocity, and transit times through the AVM fistulae. In this study we tried to visualize both the AVM vascular substructure and dynamics of discrete microdroplets traveling through the AVM using a single injection composed of both soluble and non-soluble contrast material. The contrast injection is traced with high-speed digital subtraction angiography. This novel technique serves as a valuable diagnostic tool to the interventionist prior to embolization of the AVM.
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Prokopenko, T. A., N. I. Nechipurenko, A. N. Batyan, and I. D. Pashkovskaya. "APPLICATION OF LOW-INTENSITY LASER THERAPY IN CEREBROVASCULAR DISEASES." In SAKHAROV READINGS 2021: ENVIRONMENTAL PROBLEMS OF THE XXI CENTURY. International Sakharov Environmental Institute, 2021. http://dx.doi.org/10.46646/sakh-2021-1-320-321.
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The indicators of pro-, antioxidant state of blood, the distribution of the intensity of calcium lines and the morphological structure of a dehydrating plasma drop were studied in 15 patients with chronic cerebral ischemia (CCI), 23 patients with transient ischemic attack (TIA), and 20 practically healthy individuals. It was found that at the time of hospitalization in patients with CCI and TIA there are differences from healthy individuals in the spatial distribution of calcium, morphological structure of plasma, pro, antioxidant state of the blood, which tend to normalize after a course of intravenous laser blood irradiation.
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Prokopenko, T. A., N. I. Nechipurenko, A. N. Batyan, and I. D. Pashkovskaya. "APPLICATION OF LOW-INTENSITY LASER THERAPY IN CEREBROVASCULAR DISEASES." In SAKHAROV READINGS 2021: ENVIRONMENTAL PROBLEMS OF THE XXI CENTURY. International Sakharov Environmental Institute, 2021. http://dx.doi.org/10.46646/sakh-2021-1-320-321.
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The indicators of pro-, antioxidant state of blood, the distribution of the intensity of calcium lines and the morphological structure of a dehydrating plasma drop were studied in 15 patients with chronic cerebral ischemia (CCI), 23 patients with transient ischemic attack (TIA), and 20 practically healthy individuals. It was found that at the time of hospitalization in patients with CCI and TIA there are differences from healthy individuals in the spatial distribution of calcium, morphological structure of plasma, pro, antioxidant state of the blood, which tend to normalize after a course of intravenous laser blood irradiation.
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Ley, Obdulia, and Yildiz Bayazitoglu. "Temperature Distribution in a Realistic Human Head During Selective and Whole Body Cooling and During Circulatory Arrest." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-61101.
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Using a realistic adult head and neck geometry and a thermal model, the transient temperature distribution is calculated during different cooling strategies and variations in cerebral blood flow. Given the importance of brain temperature in clinical therapy, temperature calculations using thermal models are necessary to optimize hypothermic therapies commonly employed for brain protection during surgery or in the treatment of brain injury. The calculations presented here show the effect of selective and whole body cooling strategies on the temperature gradients in the head; the time required to reach a stationary temperature distribution for the different cooling strategies; the importance of thermal stabilization when using deep hypothermic circulatory arrest, and the effect of selective head cooling in periods of lack of blood flow to control temperature gradients in the brain tissue produced by residual metabolic activity.
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Montecchio, G. P., P. Custodi, S. Carbone, C. Bendotti, and F. Piovella. "TICLOPIDINE AND INDOBUFEN: EFFECTS ON HAEMOSTATIC FUNCTIONS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643418.
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Many different mechanisms are involved in thrombus formation. We compared the effects on haemostatic function of two drugs having different mechanism of action, the one interfering with arachidonic acid metabolic cascade (Indobufen) and the other (Ticlopidine) independent from it. 18 adult patients of both sexes suffering from cerebral Transient Ischaemic Attack (T.I.A.) or Reversible Ischaemic Neurologic Disability (R.I.N.D.) have been treated with Indobufen (400 mg daily) or Ticlopidine (500 mg daily) for three weeks. The effects on various haemostatic parameters including bleeding time, platelet adhesion to glass beads, platelet aggregation induced by ADP, collagen, platelet activating factor (PAF )f have been evaluated at the beginning and at the end of treatment. Both drugs prolonged the bleeding time, Ticlopidine being more effective than Indobufen. ADP-induced platelet aggregation was more effectively inhibited by Ticlopidine, while Indobufen was more effective on collagen-induced aggregation. PAF-induced platelet aggregation was inhibited by Ticlopidine, while Indobufen was ineffective. Platelet adhesion to glass beads was not influenced by treatment with either drugs. In conclusion, both drugs confirmed to be effective in inhibiting haemostatic function although with different mechanisms. Ticlopidine seems to be involved in more mechanisms, interfering with platelet aggregation induced by ADP, collagen, PAF and prolonging the bleeding time. Indobufen interferes with platelet aggregation induced by ADP and collagen, is less effective in prolonging the bleeding time, and does not affect PAF-induced platelet aggregation.
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Watanuki, Keiichi, Kenta Hirayama, and Kazunori Kaede. "Brain Activation Analysis of Voluntary Movement and Passive Movement Using Near-Infrared Spectroscopy." In ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/detc2012-71273.
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During neural activity in the brain, humans transmit and process information and decide upon actions or responses. When neural activity occurs, blood flow and blood quantity increase in the tissue near the active neurons, and the ratio of oxygenated to deoxygenated hemoglobin in the blood changes. In this paper, we used near-infrared spectroscopy (NIRS) to determine the state of hemoglobin oxygenation at the cerebral surface and on that basis performed real-time color mapping of brain activity (the brain activation response) in the target regions. In this paper, we describe measurements of brain activation using NIRS so as to clarify any differences between conscious and unconscious movement. Bio-locomotion is divided into voluntary movements, which are made voluntarily and consciously, and passive movements, which are made passively and unconsciously. Accordingly, in this paper we investigate the brain activation associated with these two types of movements. The subject successively moves his/her lower legs through knee bends. We measure the brain activities while the subject, who is sitting on a chair moves back and forth. In addition, we carry out an experiment on the effects of the existence or nonexistence of movement caused by vibration on brain activities to consider the results.
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Zhu, Liang, and Chenguang Diao. "Computer-Aided Analysis of Transient and Steady State Temperature Distribution in Human Brain During Selective Cooling of Head Surface and Rewarming for Head Injury Patients." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-33686.
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In recent years, mild or moderate hypothermia during which brain temperature is reduced to 30–35°C has been proposed for clinical use as an adjunct for achieving protection from cerebral ischemia and traumatic brain injury. There are two approaches for achieving a reduction in brain temperature. One is via systemic hypothermia where the whole body is cooled. This approach may produce deleterious systemic complications and require intensive monitoring. Another approach is called selective brain cooling (SBC) in which the brain is selectively cooled while the rest of the body is kept at normal temperature. Clinically feasible SBC protocols include head hood or helmet with water or chemical cooling, head immersion in iced water, nasophyaryngeal cooling after tracheal intubation, and intro-carotid flushing. Simply packing ice or wearing cooling helmet is easy to implement. Previous theoretical study [Zhu and Diao, 2001] suggests that it is feasible to achieve mild hypothermia via head surface cooling. However, most physicians believe that it takes a much longer time to reduce the brain temperature using head surface cooling. In this study, a three-dimensional theoretical model is developed to study the transient and steady state temperature distribution in the brain during SBC. The effect of regionally varying local blood perfusion rate in the brain tissue on the temporal and spatial temperature gradient is examined. Other factors including the brain size and the thermal contact resistance between the cooling medium and the head scalp are evaluated in the simulation.