scholarly journals The Effect of Acetazolamide on Regional Cerebral Blood Oxygenation at Rest and under Stimulation as Assessed by MRI

1994 ◽  
Vol 14 (5) ◽  
pp. 742-748 ◽  
Author(s):  
Harald Bruhn ◽  
Andreas Kleinschmidt ◽  
Henning Boecker ◽  
Klaus-Dietmar Merboldt ◽  
Wolfgang Hänicke ◽  
...  
Keyword(s):  
Cerebral Perfusion ◽  
Blood Oxygenation ◽  
Reserve Capacity ◽  
Resonance Imaging ◽  
Gradient Echo ◽  
Vasomotor Tone ◽  
Regional Cerebral Blood ◽  
Cerebrovascular Reserve ◽  
Magnetic Resonance Imaging Mri ◽  
Cerebral Blood Oxygenation

The sensitivity of gradient echo magnetic resonance imaging (MRI) to changes in cerebral blood oxygenation (CBO) has been introduced for mapping functional brain activation. Here, we report that this approach allows monitoring autoregulation in the human brain under vasodilatory stress. Following the administration of acetazolamide, signal intensities of deoxyhemoglobin-sensitive images increased in cortical and subcortical gray matter and to a lesser extent in white matter. This result reflects a venous hyperoxygenation stemming from an increase in cerebral perfusion with oxygen consumption remaining constant. In addition, pharmacologic induction of vasodilation attenuated activity-related MRI signal changes in the visual cortex under photic stimulation. Although intersubject variability was high, this finding indicates individually persisting autoregulatory responsiveness to functional challenge despite an “exhausted” reserve capacity. It is suggested that recording CBO by MRI will foster our understanding of modulation of vasomotor tone and cerebral perfusion. Furthermore, this technique may prove valuable for assessing the cerebrovascular reserve capacity in patients with carotid artery occlusive disease.

Magnetic Resonance Imaging of Regional Cerebral Blood Oxygenation Changes Under Acetazolamide in Carotid Occlusive Disease

Stroke ◽  
1995 ◽  
Vol 26 (1) ◽  
pp. 106-110 ◽  
Author(s):  
Andreas Kleinschmidt ◽  
Helmuth Steinmetz ◽  
Matthias Sitzer ◽  
Klaus-Dietmar Merboldt ◽  
Jens Frahm
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Blood Oxygenation ◽  
Occlusive Disease ◽  
Resonance Imaging ◽  
Regional Cerebral Blood ◽  
Carotid Occlusive Disease ◽  
Cerebral Blood Oxygenation

scholarly journals Cortical microinfarcts in memory clinic patients are associated with reduced cerebral perfusion

2019 ◽  
Vol 40 (9) ◽  
pp. 1869-1878 ◽  
Author(s):  
Doeschka A Ferro ◽  
Henri JJM Mutsaerts ◽  
Saima Hilal ◽  
Hugo J Kuijf ◽  
Esben T Petersen ◽  
...  
Keyword(s):  
Arterial Spin Labeling ◽  
Cerebral Perfusion ◽  
Region Of Interest ◽  
Resonance Imaging ◽  
Memory Clinic ◽  
Anterior Circulation ◽  
Cortical Gray Matter ◽  
Arterial Transit Time ◽  
Magnetic Resonance Imaging Mri ◽  
Continuous Arterial Spin Labeling

Cerebral cortical microinfarcts (CMIs) are small ischemic lesions associated with cognitive impairment and dementia. CMIs are frequently observed in cortical watershed areas suggesting that hypoperfusion contributes to their development. We investigated if presence of CMIs was related to a decrease in cerebral perfusion, globally or specifically in cortex surrounding CMIs. In 181 memory clinic patients (mean age 72 ± 9 years, 51% male), CMI presence was rated on 3-T magnetic resonance imaging (MRI). Cerebral perfusion was assessed from cortical gray matter of the anterior circulation using pseudo-continuous arterial spin labeling parameters cerebral blood flow (CBF) (perfusion in mL blood/100 g tissue/min) and spatial coefficient of variation (CoV) (reflecting arterial transit time (ATT)). Patients with CMIs had a 12% lower CBF (beta = −.20) and 22% higher spatial CoV (beta = .20) (both p < .05) without a specific regional pattern on voxel-based CBF analysis. CBF in a 2 cm region-of-interest around the CMIs did not differ from CBF in a reference zone in the contralateral hemisphere. These findings show that CMIs in memory clinic patients are primarily related to global reductions in cerebral perfusion, thus shedding new light on the etiology of vascular brain injury in dementia.

scholarly journals Juxtacortical susceptibility changes in progressive multifocal leukoencephalopathy at the gray–white matter junction correlates with iron-enriched macrophages

2021 ◽  
pp. 135245852199965
Author(s):  
Kedar R Mahajan ◽  
Moein Amin ◽  
Matthew Poturalski ◽  
Jonathan Lee ◽  
Danielle Herman ◽  
...  
Keyword(s):  
White Matter ◽  
Progressive Multifocal Leukoencephalopathy ◽  
Central Nervous System Lymphoma ◽  
Susceptibility Weighted Imaging ◽  
Resonance Imaging ◽  
Gradient Echo ◽  
Total N ◽  
Mri Brain ◽  
Fluid Attenuated Inversion Recovery ◽  
Magnetic Resonance Imaging Mri

Objective: Describe magnetic resonance imaging (MRI) susceptibility changes in progressive multifocal leukoencephalopathy (PML) and identify neuropathological correlates. Methods: PML cases and matched controls with primary central nervous system lymphoma (PCNSL) were retrospectively identified. MRI brain at 3 T and 7 T were reviewed. MRI-pathology correlations in fixed brain autopsy tissue were conducted in three subjects with confirmed PML. Results: With PML ( n = 26 total, n = 5 multiple sclerosis natalizumab-associated), juxtacortical changes on susceptibility-weighted imaging (SWI) or gradient echo (GRE) sequences were noted in 3/3 cases on 7 T MRI and 14/22 cases (63.6%) on 1.5 T or 8/22 (36.4%) 3 T MRI. Similar findings were only noted in 3/25 (12.0%) of PCNSL patients (odds ratio (OR) 12.83, 95% confidence interval (CI), 2.9–56.7, p < 0.001) on 1.5 or 3 T MRI. On susceptibility sequences available prior to diagnosis of PML, 7 (87.5%) had changes present on average 2.7 ± 1.8 months (mean ± SD) prior to diagnosis. Postmortem 7 T MRI showed SWI changes corresponded to areas of increased iron density along the gray–white matter (GM-WM) junction predominantly in macrophages. Conclusion: Susceptibility changes in PML along the GM-WM junction can precede noticeable fluid-attenuated inversion recovery (FLAIR) changes and correlates with iron accumulation in macrophages.

Void distribution and susceptibility differences in ceramic materials using MRI

1993 ◽  
Vol 8 (3) ◽  
pp. 655-661 ◽  
Author(s):  
Anton S. Wallner ◽  
William M. Ritchey
Keyword(s):  
Porous Ceramic ◽  
Ceramic Materials ◽  
Signal Loss ◽  
Resonance Imaging ◽  
Gradient Echo ◽  
Intensity Measurements ◽  
Magnetic Resonance Imaging Mri ◽  
Processing Differences ◽  
Porous Ceramic Materials ◽  
Solvent Permeation

Magnetic Resonance Imaging (MRI) is applied to porous ceramic materials to study structural properties. In ceramics, processing differences create inhomogeneous binder distribution in the materials which can cause the formation of regions with differing densities and voids. These defects can be observed with MRI using solvent permeation. Fractional porosity obtained by using image intensity measurements and weight gain due to solvent permeation can be correlated. Dark regions in the image are due to defects such as closed voids, pockets of binder, or agglomerates. Defects such as voids or agglomerates usually have different magnetic susceptibilities. This difference causes artifacts in the image. By exploiting the increase in signal loss using a gradient-echo sequence, apparent enhancement of voids in ceramics is achieved.

scholarly journals Idiopathic Bilateral Bloody Tearing

2015 ◽  
Vol 2015 ◽  
pp. 1-2 ◽  
Author(s):  
Emrullah Beyazyıldız ◽  
Yasemin Özdamar ◽  
Özlem Beyazyıldız ◽  
Hasan Yerli
Keyword(s):  
Pathological Examination ◽  
Resonance Imaging ◽  
Gradient Echo ◽  
Imaging Studies ◽  
Endoscopic Evaluation ◽  
Endometrial Cells ◽  
Squamous Cells ◽  
Pathological Analysis ◽  
Underlying Causes ◽  
Magnetic Resonance Imaging Mri

Bloody tear is a rare and distinct clinic phenomenon. We report a case presenting with the complaint of recurrent episodes of bilateral bloody tearing. A 16-year-old girl presented to our clinic with complaint of bloody tearing in both eyes for 3 months. Bloody tearing was not associated with her menses. A blood-stained discharge from the punctum was not observed during the compression of both nasolacrimal ducts. Nasolacrimal passage was not obstructed. Imaging studies such as dacryocystography and gradient-echo magnetic resonance imaging (MRI) of nasolacrimal canal were normal. Intranasal endoscopic evaluation was normal. We collected samples from bloody tears two times and pathological examination was performed. Pathological analysis showed lots of squamous cells and no endometrial cells; dysplastic cells were found. Further evaluations for underlying causes were unremarkable. No abnormalities were found in ophthalmologic, radiologic, and pathologic investigations. This condition is likely a rare abnormality and the least recognized aetiology for the idiopathic phenomenon.

scholarly journals Noninvasive near Infrared Spectroscopy Monitoring of Regional Cerebral Blood Oxygenation Changes during Peri-Infarct Depolarizations in Focal Cerebral Ischemia in the Rat

1997 ◽  
Vol 17 (9) ◽  
pp. 950-954 ◽  
Author(s):  
Tilo Wolf ◽  
Ute Lindauer ◽  
Uwe Reuter ◽  
Tobias Back ◽  
Arno Villringer ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Spreading Depression ◽  
Focal Ischemia ◽  
Artery Occlusion ◽  
Blood Oxygenation ◽  
Regional Cerebral Blood ◽  
Cerebral Blood Oxygenation ◽  
Cerebral Artery Occlusion

Intermittent peri-infarct depolarizations (PID), which spread from the vicinity of the infarction over the cortex, have been reported in focal ischemia. These depolarizations resemble cortical spreading depression except that they damage the cortex and enlarge the infarct volume possibly because of compromised oxygen delivery. The main purpose of this study was to evaluate the noninvasive technique of near-infrared spectroscopy (NIRS) for the identification of PID and to evaluate its capability for further pathophysiological studies. We used male barbiturate-anesthetized Wistar rats (n = 10) in which middle cerebral artery occlusion had been performed with a surgical thread. Middle cerebral artery occlusion resulted in a drop in parietally measured regional cerebral blood flow (laser Doppler flowmetry) to 31 ± 8% of baseline flow. Six ± 4 minutes after the induction of focal ischemia, 5 ± 2 direct current deflections were recorded during a one-hour measurement period which may be regarded as PID. Measuring regional cerebral blood oxygenation changes with a NIRO 500 revealed dynamic concentration changes in the three chromophores oxyhemoglobin [HbO2], deoxyhemoglobin [Hb], and the oxidized form of cytochrome aa3 [CytO] during PID. Typically, an initial slight decrease of [HbO2] (−6.1 ± 1.7 arbitrary units [AU]) and an increase of [Hb] (+1 1.5 ± 7.7 AU) were followed by an increase of [HbO2] (+10.8 ± 4.7 AU) and a decrease of [Hb] (−4.7 ± 5.5 AU); [CytO] decreased during the depolarizations (−2.0 ± 1.2 AU). We conclude that NIRS can detect typical PID-associated changes in blood oxygenation. We hypothesize that during the course of PID, unlike “normal” spreading depression, hypoxygenation precedes hyperoxygenation of the microcirculation in a given cortex volume as the depolarization wave propagates through hemodynamically compromised to intact tissue. This would accord with the known damaging effect of PID. The NIRS “fingerprint” of PID encourages the search for PID during early stroke in patients.

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