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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A rapidly rotating single-photon emission tomograph was used to study regional cerebral blood flow by 133Xenon inhalation. Using a rotation speed of 180 degrees/5 sec a tomographic picture of the average Xenon concentration in 3 slices is obtained. By taking a sequence of 4 one-minute tomograms during and after a one-minute 133Xenon inhalation period a flow-dependent variation in local isotope concentration is seen. This sequence is used for calculating CBF by a deconvolution procedure. The CBF maps have a spatial resolution of approximately 1.7 cm (FWHM). This preliminary study comprises normal subjects and 10 unselected patients with stroke. The CBF tomograms localized appropriate ischemic areas in all 10 patients. In one patient the conventional x-ray tomogram was negative, while the flow tomogram clearly showed a decreased flow in consonance with the clinical findings. Regional cerebral blood flow measured tomographically by 133Xenon inhalation circumvents the extra-cranial contamination and the superposition of intracranial tissues that hamper 133Xenon inhalation flow studies using stationary detectors.
Stroke
PMID:Regional cerebral blood flow in stroke by 133Xenon inhalation and emission tomography. 697 35

Positron emission tomography (PET) makes it possible to employ an in vivo autoradiographic paradigm to measure regional cerebral blood flow (rCBF) in man. In this study, we synthesized the positron-emitting radiopharmaceutical 11C-iodoantipyrine (11C-IAP) and validated its suitability as a CBF tracer. 11C ( T and one-half 20.4 min) was produced by the (p,alpha) nuclear reaction on 14N. 11C-methyl iodide was used to methylate 3-methyl-1-phenyl-2-pyrazolin-5-one to form 11C-antipyrine, which was iodinated. Radiochemical purity of the 11C-IAP product was 93-98% except as described below. rCBF was measured with 11C-IAP in nitrous oxide-anesthetized Wistar rats by the method of indicator fractionation, and values were compared with rCBF values measured with simultaneously administered commercially produced 14C-IAP. rCBF was studied over a range of arterial Pco2 values (31-58 mm Hg, mean 43.0 +/- 3.5). Mean rCBF data for the 2 tracers agreed to within 4.8% for cerebral hemispheral samples, 3.8% for cerebellum, and 5.3% for brainstem. Mean values (+/- SEM) for rCBF using 11C-IAP were 1.67 +/- 0.20 ml gm-1 min-1 for cerebral hemispheres; 1.32 +/- 0.17 for cerebellum; and 1.50 +/- 0.21 for brainstem. When chromatographic analysis revealed tracer impurity, rCBF, as measured with 11C-IAP, fell consistently below values obtained with 14C-IAP. The data indicate that 11C-IAP, when properly synthesized and submitted to batch-by-batch quality control, may be suitable for measuring rCBF in man by emission tomography.
Stroke
PMID:11C-Iodoantipyrine for the measurement of regional cerebral blood flow by positron emission tomography. Validation studies. 697 14

A thermal diffusion flow probe incorporating a Peltier stack has been found to give a quantitative dynamic assessment of cortical blood flow in both the laboratory and clinical settings. Further calibration characteristics of the probe were evaluated by correlation with the fast component of Xe133 clearance in cats. The correlation has some linear characteristics but is better defined by the equation: CBFp = phi(1/delta V - 1/delta Vo) Where CBFp is flow in ml/100 g/min, delta V is the voltage difference of the thermocouples, and delta Vo is the voltage difference of the thermocouples with no flow, which was 342.8 +/- 12.9 microv. Phi describes the characteristics of the probe and was determined to be 52,431.2 +/- 4796.3. The average deviation of the calculated curve from the experimental data points was +/- 6.3. The calculated phi differed markedly from the mean when Xe133 fast component flows were less than 35 ml/100 g/min. This is evidence that CBF as measured by Xe133 clearance analyzed by the bicompartmental technique loses accuracy at lower flows. The thermal diffusion flow probe is a good device for evaluation of flow in acute ischemia models since it can delineate abrupt flow variations. Theoretically the flow probe can accurately measure flow at ischemic levels.
Stroke
PMID:Cortical blood flow: thermal diffusion vs isotope clearance. 703 4

Changes of PjO2 values of internal jugular vein were monitored in patients with various types of cerebrovascular disease. The significance of PjO2 monitoring was evaluated. 1) Control value of PjO2 in thirteen normal control cases was 36.7 +/- 1.9 mmHg (mean +/- SD). 2) Limit of brain hypoxia showing no neurological sign and symptom in patients with occlusive cerebrovascular disease was studied by the stepwise reduction of arterial blood pressure, using drip infusion of trymetaphan camsylate, under the careful monitoring of signs and symptoms and monitoring of PjO2 and EEG. Appearance of signs and symptoms of brain hypoxia were checked by yawning and EEG slowing. At the time of the appearance of brain hypoxia PjO2 was 28.6 +/- 3.2 mmHg. 3) CO2 reactivity of CBF was studied in patients with occlusive cerebrovascular disease. Relation between PaCO2 and PjO2 was as follows; PjO2 = 0.68 . PaCO2 + 7.55 4) Within 24 hours after the onset of stroke, ipsilateral PjO2 of the cases with disturbance of consciousness was lower than that of the cases without disturbance of consciousness, which might indicate the significant decrease of CBF in the former cases. During 3rd to 7th day after the onset the cases with disturbance of consciousness showed the significant elevation of PjO2, which might indicate the reduction of cerebral metabolism. 5) The elevation of ipsilateral PjO2 were well correlated to the degree of hemispheric brain swelling. 6) During general convulsion, high level of PjO2 values were observed. 7) PjO2 values were inversely correlated to the hemoglobin values after blood transfusion, which was mainly due to the decrease of CBF by high content of hemoglobin.
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PMID:[Monitoring system of cerebral blood flow and cerebral metabolism. Part II. Relationship between internal jugular O2 tention and cerebral blood flow (author's transl)]. 709 62

A problem in the measurement of cerebral blood flow with 133Xenon is the presence of extra-cerebral counts in the total counts recorded with a collimated gamma ray detector looking at the brain. A method of studying qualitatively the contribution of this extra-cranial component in patients is described. This entails the sequential accumulation of gamma ray spectra recorded during the clearance phase of 133Xenon from the brain. It is shown that different CBF indices are obtained for various regions of the recorded gamma ray spectra. The principal component of the extra-cerebral counts at 15 minutes postinjection appears to be intra-cranial, and not the scalp as assumed previously in the spectrum subtraction method.
Stroke
PMID:Analysis of the gamma ray spectra recorded in the use of Xenon-133 for cerebral blood flow studies. 710 55

Progressive brain damage after transient cerebral ischemia may be related to changes in postischemic cerebral blood flow and metabolism. Regional cerebral blood flow (rCBF) and cerebral glucose utilization (rCGU) were measured in adult rats prior to, during (only rCBF), and serially after transient forebrain ischemia. Animals were subjected to 30 minutes of forebrain ischemia by occluding both common carotid arteries 24 hours after cauterizing the vertebral arteries. Regional CBF was measured by the indicator-fractionation technique using 4-iodo-[14C]-antipyrine. Regional CGU was measured by the 2-[14C]deoxyglucose method. The results were correlated with the distribution and progression of ischemic neuronal damage in animals subjected to an identical ischemic insult. Cerebral blood flow to forebrain after 30 minutes of moderate to severe ischemia (less than 10% control CBF) was characterized by 5 to 15 minutes of hyperemia; rCBF then fell below normal and remained low for as long as 24 hours. Post-ischemic glucose utilization in the forebrain, except in the hippocampus, was depressed below control values at 1 hour and either remained low (neocortex, striatum) or gradually rose to normal (white matter) by 48 hours. In the hippocampus, glucose utilization equaled the control value at 1 hour and fell below control between 24 and 48 hours. The appearance of moderate to severe morphological damage in striatum and hippocampus coincided with a late rise of rCBF above normal and with a fall of rCGU; the late depression of rCGU was usually preceded by a period during which metabolism was increased relative to adjacent tissue. Further refinement of these studies may help identify salvageable brain after ischemia and define ways to manipulate CBF and metabolism in the treatment of stroke.
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PMID:Regional cerebral blood flow and glucose metabolism following transient forebrain ischemia. 710 26

Regional cerebral blood flow and vasomotor reactivity were measured in 33 patients with surgically remediable hemispheric ischemia by the 133Xe inhalation method prior to superficial temporal to middle cerebral artery (STA-MCA) by-pass. Thirteen patients also underwent LCBF and L lambda measurements by the stable xenon CT method for comparison. Twenty-four had proximal occlusion of one or both internal carotid arteries, 9 had intracranial occlusive disease (4 internal carotid, 5 middle cerebral). Measurements were repeated at intervals up to 30 months following surgery and compared to measurements in a similar group (N = 13) treated medically. In the surgically treated group 22 patients had recurrent TIAs, of whom 12 also had minor residual neurological deficits from recent small cerebral infarctions with potential for recovery (RINDs) while the remaining 11 had RINDs without TIAs. After surgery 28 improved with cessation of TIAs and/or neurological recovery, 3 remained unchanged, 2 cases worsened. Compared to age-matched normal hemispheric F1 (gray matter) values, pre-operative F1 values in the STA-MCA group were reduced in both ischemic and opposite hemispheres. Ischemic regions showed imparied vasomotor reactivity to 5% CO2 or 100% O2 inhalation. After surgery, mean hemispheric F1 values increased + 12.8% on the by-pass side and + 10.5% on the contralateral side. Mean F1 increases reached a maximum 3 months after by-pass, most evident in ipsilateral frontal regions (+ 24.2%). Vasomotor reactivity did not significantly improve. Medically treated cases did not show similar F1 increases. Thirteen with carotid occlusive disease (8 with TIAs, 5 with small recent infarcts) underwent CT LCBF and L lambda measurements before and after STA-MCA by-pass. Cases with recent infarcts showed reduced LCBF and L lambda values which increased significantly after STA-MCA by-pass, however the total group operated upon showed only trends for CBF increases, probably due to large standard deviations encountered in serial measurements.
Stroke
PMID:Redistribution of cerebral blood flow following STA-MCA by-pass in patients with hemispheric ischemia. 714 91

Air embolization of the brain produces cerebral ischemia that can be focal and reversible. The method has previously been hampered by (1) lack of selective arterial injection of the embolus, (2) disruption of local hemodynamic relationships by ligation of major arterial channels, (3) excessive volume of the air embolus, and (4) uncontrolled bubble size. To minimize these factors, a technique was devised in the rat whereby a fine catheter was advanced through a branch of the external carotid artery into the internal carotid artery. Air emboli of 5 microliters were found to arrest blood flow and to attenuate electrical activity in the ipsilateral cerebral hemisphere for seconds to a couple of minutes. The duration of ischemia varied from region to region, and it tended to be prolonged by arterial hypotension. In the nonembolized hemisphere, CBF never declined abruptly (indicating no cross-over of air) although electrical activity was suppressed in two-thirds of the animals.
Stroke
PMID:Experimental air embolism of the brain: an analysis of the technique in the rat. 714 3

A scintillation camera connected to a dedicated computer system was employed for atraumatic CBF measurements in 43 patients after intravenous injection of 35 to 55 mCi 133Xe in saline solution. To validate this method results were compared to flow values in the same patients measured after intracarotid Xe injection. While the correlation between i.c. and i.v. values was not satisfactory when a high resolution collimator was used, a high sensitivity collimator improved count rates and yielded CBF values after i.v. in agreement with those from i.c. studies. For mean hemispheric flow, the correlation coefficient between the methods was 0.93 and the standard deviation of the i.v. value for a given i.c. value was 2.93. The correlation coefficients for 13 regions were between 0.55 and 0.85. These correlation coefficients are comparable to those obtained with multidetector equipment. Ischemic regions could be accurately detected, and the flow values in these areas were significantly related (r = 0.81). Values in 6 healthy volunteers were in the normal range reported by other investigators. One disadvantage of the camera is that measurements are restricted to one hemisphere, but selection of recording areas is not limited to the position of single probes and may be changed during analysis of the data permitting analysis of flow in irregularly-shaped, pathologically-perfused regions. The results indicate that the scintillation camera is a useful tool for clinical rCBF studies.
Stroke
PMID:Atraumatic CBF measurement with the scintillation camera. Comparison with intracarotid rCBF values. 722 58

Measurements of total and regional cerebral blood flow in paralyzed rats maintained on 70% N2O/30% O2 obtained by a diffusible tracer technique, iodoantipyrine, and by a particle distribution method, microspheres, have been compared. Total CBF values were in good agreement, 0.86 +/- 0.07 ml/g/min (PaCO2 37.3 +/- 1.5, iodoantipyrine method) and 0.88 +/- 0.02 (PaCO2 36.2 +/- 0.8, microsphere method). Regional cerebral blood flows showed good agreement with the 2 methods, with highest flow in the colliculi, striatum and cerebral cortex and lowest flows in the hypothalamus, pons medulla and cerebellum. The iodoantipyrine method is technically easier to perform and had a higher precision.
Stroke
PMID:Regional cerebral blood flow in the rat as determined by particle distribution and by diffusible tracer. 735 28


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