scholarly journals Preserved Acetazolamide Reactivity in Lacunar Patients with Severe White-Matter Lesions: 15O-Labeled Gas and H2O Positron Emission Tomography Studies

2012 ◽  
Vol 32 (5) ◽  
pp. 844-850 ◽  
Author(s):  
Tomohisa Nezu ◽  
Chiaki Yokota ◽  
Toshiyuki Uehara ◽  
Miho Yamauchi ◽  
Kazuhito Fukushima ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
White Matter ◽  
White Matter Lesions ◽  
Oxygen Metabolism ◽  
Emission Tomography ◽  
Oxygen Extraction Fraction ◽  
Centrum Semiovale ◽  
Vascular Reserve ◽  
Positron Emission ◽  
Artery Disease

Limited evidence exists on the relationships between severity of white-matter lesions (WMLs) and cerebral hemodynamics in patients without major cerebral artery disease. To examine changes of cerebral blood flow (CBF), oxygen metabolism, and vascular reserve capacity associated with severity of WML in patients with lacunar stroke, we used a positron emission tomography (PET). Eighteen lacunar patients were divided into two groups according to the severity of WMLs, assessed by Fazekas classification; grades 0 to 1 as mild WML group and grades 2 to 3 as severe WML group. Rapid dual autoradiography was performed with 15O-labeled gas-PET followed by 15O-labeled water-PET with acetazolamide (ACZ) challenge. Compared with the mild WML group, the severe WML group showed lower CBF (20.6 ± 4.4 versus 29.9 ± 8.2 mL/100 g per minute, P = 0.008), higher oxygen extraction fraction (OEF) (55.2 ± 7.4 versus 46.7 ± 5.3%, P = 0.013), and lower cerebral metabolic rate of oxygen (CMRO2) (1.95 ± 0.41 versus 2.44 ± 0.42 mL/100 g per minute, P = 0.025) in the centrum semiovale. There were no significant differences in the ACZ reactivity between the two groups (48.6 ± 22.6% versus 42.5 ± 17.2%, P = 0.524). Lacunar patients with severe WMLs exhibited reduced CBF and CMRO2, and increased OEF in the centrum semiovale. The ACZ reactivity was preserved in both patients with severe and mild WMLs in each site of the brain.

scholarly journals Measurement of End-Capillary Po2 with Positron Emission Tomography

1988 ◽  
Vol 8 (3) ◽  
pp. 403-410 ◽  
Author(s):  
N. M. Alpert ◽  
R. B. Buxton ◽  
J. A. Correia ◽  
R. M. Katz ◽  
R. H. Ackerman
Keyword(s):  
Positron Emission Tomography ◽  
Oxygen Saturation ◽  
Normal Subjects ◽  
Oxygen Metabolism ◽  
Emission Tomography ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Protein Levels ◽  
Extraction Fraction ◽  
Positron Emission

The analysis of positron emission tomography measurements of oxygen metabolism has been extended to provide a quantitative estimate of end-capillary Po2. The principle of this extension rests on the idea that the oxygen extraction fraction can be used to calculate the end-capillary oxygen saturation of the blood. The relation between oxygen saturation and Po2 is obtained through the oxygen dissociation curve. Our studies show that in addition to the local oxygen extraction fraction, arterial Po2 and pH values are needed in the calculation, whereas fairly large variations in factors such as Pco2, hematocrit, hemoglobin, and plasma protein levels have little or no effect. Rough estimates of end-capillary Po2 can be made using standard o2 dissociation nomograms. Blood gas and acid-base properties of blood have been known for decades, making it possible to account accurately for individual differences that may be encountered when studying patients. Measurements in nine normal subjects yielded a mean end-capillary Po2 value of 31.2 mm Hg. The ability to make a quantitative visualization of altered patterns of end-capillary Po2 provides an additional dimension to the investigation of stroke disease and tumor metabolism.

scholarly journals Elevated Cerebellar Glucose Metabolism in Microvascular White Matter Disease: Normal Aging and Alzheimer's Disease

1988 ◽  
Vol 8 (3) ◽  
pp. 433-435 ◽  
Author(s):  
A. Klinger ◽  
M. J. de Leon ◽  
A. E. George ◽  
J. D. Miller ◽  
A. P. Wolf
Keyword(s):  
Computed Tomography ◽  
Positron Emission Tomography ◽  
White Matter ◽  
White Matter Lesions ◽  
Emission Tomography ◽  
Periventricular White Matter ◽  
White Matter Disease ◽  
Metabolic Rates ◽  
Positron Emission ◽  
Periventricular White Matter Lesions

Young normal, elderly, and clinically diagnosed Alzheimer disease subjects who had undergone positron emission tomography (PET) and computed tomography (CT) examinations were studied to determine the effect of periventricular white matter lesions on cerebellar glucose metabolic rates. PET-determined cerebellar metabolic rates were elevated in subjects with periventricular white matter lesions. These results suggest the cautious use of cortical-to-cerebellar ratios in future PET or single-photonemission CT (SPECT) studies.

scholarly journals Outcome of Acutely Ischemic Brain Tissue in Prolonged Middle Cerebral Artery Occlusion: A Serial Positron Emission Tomography Investigation in the Baboon

2004 ◽  
Vol 24 (5) ◽  
pp. 495-508 ◽  
Author(s):  
Cyrille Giffard ◽  
Alan R. Young ◽  
Nacer Kerrouche ◽  
Jean-Michel Derlon ◽  
Jean-Claude Baron
Keyword(s):  
Positron Emission Tomography ◽  
At Risk ◽  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Oxygen Metabolism ◽  
Emission Tomography ◽  
Oxygen Extraction Fraction ◽  
Mca Occlusion ◽  
Positron Emission ◽  
Time Point

Thrombolysis within 3 to 6 hours of symptom onset is recommended therapy for acute middle cerebral artery (MCA) stroke, but recent imaging studies in humans suggest that the penumbra may last much longer in some patients. It is therefore important to study the events that take place with occlusions that last longer than 6 hours. Based upon positron emission tomography (PET), the tissue with high oxygen extraction fraction (OEF) is at risk of infarction. In a previous sequential PET study in anesthetized baboons, we documented that when reperfusion was initiated at 6 hours after MCA occlusion, the region with the acutely highest OEF was not incorporated within the final magnetic resonance imaging (MRI)-defined infarct, suggesting reperfusion prevented such demise. In agreement with this hypothesis, we report here using the same sequential PET paradigm with final chronic-stage volume MRI that a 20-hour MCA occlusion resulted in, on average, 36% of the highest OEF area being recruited into the final infarct. We also found that the portion of the highest OEF area that went on to infarct had at the earliest time-point significantly lower cerebral blood flow and cerebral oxygen metabolism (mean reductions relative to unoccluded side, 56% and 32%, respectively) than the portion that did not (41% and 11%, respectively) and that some reperfusion occurred in the latter at second time-point, that is, before recanalization. Thus, apart from duration of occlusion, the fate of the at-risk tissue is predicated by the initial severity of the ischemia as well as by early secondary events such as partial spontaneous reperfusion.

scholarly journals Oxygen Extraction Fraction at Maximally Vasodilated Tissue in the Ischemic Brain Estimated from the Regional CO2 Responsiveness Measured by Positron Emission Tomography

1988 ◽  
Vol 8 (2) ◽  
pp. 227-235 ◽  
Author(s):  
Iwao Kanno ◽  
Kazuo Uemura ◽  
Schuichi Higano ◽  
Matsutaro Murakami ◽  
Hidehiro Iida ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Resting State ◽  
Emission Tomography ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Cross Point ◽  
Steady State Method ◽  
Extraction Fraction ◽  
Positron Emission ◽  
Vascular Responsiveness

The oxygen extraction fraction (OEF) at maximally vasodilated tissue in patients with chronic cerebrovascular disease was evaluated using positron emission tomography. The vascular responsiveness to changes in PaCO2 was measured by the H215O autoradiographic method. It was correlated with the resting-state OEF, as estimated using the 15O steady-state method. The subjects comprised 15 patients with unilateral or bilateral occlusion and stenosis of the internal carotid artery or middle cerebral artery or moyamoya disease. In hypercapnia, the scattergram between the OEF and the vascular responsiveness to changes in PaCO2 revealed a significant negative correlation in 11 of 19 studies on these patients, and the OEF at the zero cross point of the regression line with a vascular responsiveness of 0 was 0.53 ± 0.08 (n = 11). This OEF in the resting state corresponds to exhaustion of the capacity for vasodilation. The vasodilatory capacity is discussed in relation to the lower limit of autoregulation.

scholarly journals Vulnerable plaque imaging using 18F-sodium fluoride positron emission tomography

2020 ◽  
Vol 93 (1113) ◽  
pp. 20190797 ◽  
Author(s):  
Jacek Kwiecinski ◽  
Piotr J Slomka ◽  
Marc R Dweck ◽  
David E Newby ◽  
Daniel S Berman
Keyword(s):  
Coronary Artery Disease ◽  
Positron Emission Tomography ◽  
Coronary Artery ◽  
Sodium Fluoride ◽  
Imaging Modality ◽  
Emission Tomography ◽  
Plaque Morphology ◽  
Non Invasive ◽  
Positron Emission ◽  
Artery Disease

Positron emission tomography (PET) with 18F-sodium fluoride (18F-NaF) has emerged as a promising non-invasive imaging modality to identify high-risk and ruptured atherosclerotic plaques. By visualizing microcalcification, 18F-NaF PET holds clinical promise in refining how we evaluate coronary artery disease, shifting our focus from assessing disease burden to atherosclerosis activity. In this review, we provide an overview of studies that have utilized 18F-NaF PET for imaging atherosclerosis. We discuss the associations between traditional coronary artery disease measures (risk factors) and 18F-NaF plaque activity. We also present the data on the histological validation as well as show how 18F-NaF uptake is associated with plaque morphology on intravascular and CT imaging. Finally, we discuss the technical challenges associated with 18F-NaF coronary PET highlighting recent advances in this area.

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