15 research outputs found
rCBF After Tia and during Migraine Attacks
No full text TIA is usually caused by embolism from a carotid stenosis. The stenosis has no hemodynamic significance, but recent studies of regional cerebral blood flow have indicated that this occurs in a few cases. Traditionally, TIA are not considered to cause cerebral damage, but CT-studies have revealed a number of silent infarcts and rCBF measurements have shown even more persistent abnormalities of blood flow. In classic migraine, alterations of rCBF are completely different, indicating a mechanism progressing in the cerebral cortex, probably the spreading depression of Leao. Similar blood flow changes are not seen in common migraine, where tomographic rCBF determinations have been normal. </jats:p
Regional Cerebral Blood Flow Measured by Xenon-133 and [123I]Iodo-Amphetamine in Patients with Cerebrovascular Diseases
No full textImmunoglobulin Treatment Versus Plasma Exchange in Patients with Chronic Moderate to Severe Myasthenia Gravis
No full textNoninvasive Xenon-133 Measurements of Cerebral Blood Flow Using Stationary Detectors Compared with Dynamic Emission Tomography
No full text 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 in the middle cerebral artery territory shown with the tomograph. As illustrated by a case history, the nontomographic CBF unit used in this study may provide reliable and useful information in patients with occlusive cerebrovascular disease by performing repeated CBF studies and challenging the cerebral circulation with acetazolamide. </jats:p
Neuro-SPECT:On the development and function of brain emission tomography in the Copenhagen area
No full textThis review describes the development of single-photon emission tomography (SPECT) in the Copenhagen area under the leadership of the internationally renown scientist, Niels A. Lassen, and the history leading up to construction of the tomograph. Measurements of global cerebral blood flow (CBF) in the 1940s and 1950s were performed by Kety & Schmidt and Lassen & Munck. Determination of regional cerebral blood flow (rCBF) by intra-arterial injection of 133Xe and measurement with a 254-multicrystal scintillation detector and a computer system was a major step forward in the study of physiology and pathophysiology of cortical cerebral blood flow. Tomography with radioisotope ligands, including non-invasive administration, was advanced in different centres during the 1970s. An emission tomograph, the Tomomatic 64, was developed as a result of a multidisciplinary Danish and international collaboration. It was the first emission tomograph to provide dynamic data that could produce cross-sectional rCBF images. The present description of the construction and function of the Tomomatic 64 includes comparison with other contemporary and later brain-dedicated SPECT systems. Basic and clinical application of the Tomomatic 64 in Copenhagen resulted in several hundred important scientific publications and improved diagnostics for patients with a variety of neurological disorders. It is concluded that the development of the Tomomatic 64 was a major step forward in the study and examination of rCBF and brain function related to several brain disorders, in addition to vascular diseases.</p
Carotid surgery, cognitive function, and cerebral blood flow in patients with transient ischemic attacks
No full textRegional cerebral blood flow assessed by<sup>133</sup>Xe inhalation and emission tomography:Normal values
No full textRegional cerebral blood flow (rCBF) in the cerebral hemispheres and the cerebellum was measured by single photon emission computed tomography with inhalation of133Xe in 39 normal volunteers at test. The goal of this study was to assess the normal flow pattern and its variations. Five parallel tomographic slices through the brain were recorded with a resolution element of 1.7 x 1.7 x 2.0 cm (full width at half maximum). The blood flow distribution showed that the predominantly gray matter areas displayed flow approximately double that of the predominantly white matter regions. The CBF distribution was practically symmetrical with a side-to-side difference averaging 1.4 ± 1.4 ml/100 g/min. This means that a difference exceeding 4.2 ml/100 g/min (approximately 9% of mean CBF) is abnormal with a confidence level of below 5%. The measured average CBF and cerebellar blood flow were 56 ± 7 and 54 ± 6 ml/100 g/min (mean ± 1 SD), respectively. A significant correlation was found between CBF and Pco2, and between CBF and age. Repeat measurements in an additional 30 subjects showed a day-to-day variability of -0.2 ± 6.4 ml/100 g/min of the difference between the first and the second measurement. This corresponds to random methodological and biological errors of 6.4/√2 = 4.6 ml/100 g/min and is a measure of the overall intraindividual variability. Xenon-133 tomography is atraumatic and affords rCBF images free of the superposition artifacts that practically invalidate the nontomographic approaches in the studies of cerebrovascular disease. The rCBF tomograms are blurred, particularly due to Compton scatter. Relative to this factor, the errors caused by local variations in the tissue:blood partition coefficient are less important.</p
Human Regional Cerebral Blood Flow during Rapid-Eye-Movement Sleep
No full text Owing to the coupling between CBF and neuronal activity, regional CBF is a reflection of neural activity in different brain regions. In this study we measured regional CBF during polysomnographically well-defined rapid-eye-movement (REM) sleep by the use of single photon emission computerized tomography and the new tracer 99mTc- dl-hexamethylpropyleneamine. Eleven healthy volunteers aged between 22 and 27 years were studied. CBF was measured on separate nights during REM sleep and during EEG-verified wakefulness. On awakening from REM sleep, all subjects reported visual dreams. During REM sleep CBF increased by 4% (p < 0.01) in the associative visual area, while it decreased by 9% (p < 0.01) in the inferior frontal cortex. The CBF increase in the associative visual area suggests that activation of cerebral structures processing complex visual material is correlated to visual dream experiences. On the other hand, the reduced involvement of the inferior frontal cortex observed during REM sleep might explain the poor temporal organization and bizarreness often experienced in dreams. </jats:p
