scholarly journals Hypoperfusion without Ischemia Surrounding Acute Intracerebral Hemorrhage

2001 ◽  
Vol 21 (7) ◽  
pp. 804-810 ◽  
Author(s):  
Allyson R. Zazulia ◽  
Michael N. Diringer ◽  
Tom O. Videen ◽  
Robert E. Adams ◽  
Kent Yundt ◽  
...  
Keyword(s):  
Intracerebral Hemorrhage ◽  
Volume Effect ◽  
Partial Volume Effect ◽  
Emission Tomography ◽  
Oxygen Extraction Fraction ◽  
Midline Shift ◽  
Cerebral Metabolic Rate ◽  
Extraction Fraction ◽  
Positron Emission ◽  
Acute Intracerebral Hemorrhage

A zone of hypoperfusion surrounding acute intracerebral hemorrhage (ICH) has been interpreted as regional ischemia. To determine if ischemia is present in the periclot area, the authors measured cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2), and oxygen extraction fraction (OEF) with positron emission tomography (PET) in 19 patients 5 to 22 hours after hemorrhage onset. Periclot CBF, CMRO2, and OEF were determined in a 1-cm-wide area around the clot. In the 16 patients without midline shift, periclot data were compared with mirror contralateral regions. All PET images were masked to exclude noncerebral structures, and all PET measurements were corrected for partial volume effect due to clot and ventricles. Both periclot CBF and CMRO2 were significantly reduced compared with contralateral values (CBF: 20.9 ± 7.6 vs. 37.0 ± 13.9 mL 100 g−1 min−1, P = 0.0004; CMRO2: 1.4 ± 0.5 vs. 2.9 ± 0.9 mL 100 g−1 min−1, P = 0.00001). Periclot OEF was less than both hemispheric OEF (0.42 ± 0.15 vs. 0.47 ± 0.13, P = 0.05; n = 19) and contralateral regional OEF (0.44 ± 0.16 vs. 0.51 ± 0.13, P = 0.05; n = 16). In conclusion, CMRO2 was reduced to a greater degree than CBF in the periclot region in acute ICH, resulting in reduced OEF rather than the increased OEF that occurs in ischemia. Thus, the authors found no evidence for ischemia in the periclot zone of hypoperfusion in acute ICH patients studied 5 to 22 hours after hemorrhage onset.

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.

Validation of T 2 ‐based oxygen extraction fraction measurement with 15 O positron emission tomography

2020 ◽  
Vol 85 (1) ◽  
pp. 290-297
Author(s):  
Dengrong Jiang ◽  
Shengwen Deng ◽  
Crystal G. Franklin ◽  
Michael O'Boyle ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Emission Tomography ◽  
Oxygen Extraction Fraction ◽  
Oxygen Extraction ◽  
Extraction Fraction ◽  
Positron Emission ◽  
Fraction Measurement

scholarly journals Intracerebral Hemorrhage after Carotid Artery Stenting without Evidence of Hyperperfusion in Positron Emission Tomography

2007 ◽  
Vol 13 (2) ◽  
pp. 191-199 ◽  
Author(s):  
A. Shindo ◽  
N. Kawai ◽  
K. Kawakita ◽  
M. Kawanishi ◽  
T. Tamiya ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Carotid Artery ◽  
Intracerebral Hemorrhage ◽  
Left Hemisphere ◽  
Carotid Artery Stenting ◽  
Right Hemisphere ◽  
Emission Tomography ◽  
Oxygen Extraction Fraction ◽  
Positron Emission ◽  
The Right

A 75-year-old man with a recent history of transient left hemiparesis and dysarthria was referred to our hospital. Angiography showed right internal carotid artery (ICA) occlusion and left ICA 89% stenosis. Positron emission tomography (PET) showed decreased cerebral blood flow (CBF), and increased oxygen extraction fraction (OEF) and cerebral blood volume (CBV) in the right hemisphere. In the left hemisphere, CBV was increased, but CBF and OEF remained normal. One month after the transient ischemic attack, left carotid artery stenting (CAS) was performed without complications. Diffusion-weighted magnetic resonance imaging (MRI) on the day after CAS showed no fresh ischemic lesion. PET on the second day after CAS showed increased CBF and decreased OEF and CBV in the right hemisphere as compared with those before CAS. In the left hemisphere, decreased CBV was observed and CBF was slightly increased as compared with those before CAS. The postoperative course was uneventful, but on the fifth day after CAS, the patient suddenly showed a focal seizure and right motor weakness. Emergency computed tomography scanning showed massive intracranial hemorrhage with severe brain edema in the left hemisphere. Although CBF study is useful to predict the hyperperfusion syndrome, we cannot disregard the possibility of intracerebral hemorrhage after CAS for carotid artery stenosis when there is no evidence of hyperperfusion on postoperative CBF study.

scholarly journals Model Dependency and Estimation Reliability in Measurement of Cerebral Oxygen Utilization Rate with Oxygen-15 and Dynamic Positron Emission Tomography

1986 ◽  
Vol 6 (1) ◽  
pp. 105-119 ◽  
Author(s):  
Sung-Cheng Huang ◽  
DaGan Feng ◽  
Michael E. Phelps
Keyword(s):  
Positron Emission Tomography ◽  
Blood Flow ◽  
Low Noise ◽  
Emission Tomography ◽  
Oxygen Extraction Fraction ◽  
Vascular Volume ◽  
Dynamic Positron Emission Tomography ◽  
Extraction Fraction ◽  
Positron Emission ◽  
Model Configuration

The use of oxygen-15 and dynamic positron emission tomography (PET) for the measurement of CMRO was investigated in terms of the achievable accuracy of CMRO and its sensitivity to model configuration assumed in the estimation. Three models of different descriptions for the vascular radioactivity in tissue were examined by computer simulation. By simulating the tracer kinetics with one model and curve fitting them with another, it was found that the CMRO measurement was very sensitive to the model configuration used and it needed kinetic data of low noise level to determine the correct model to use. The approach of sensitivity functions and covariance matrices was used to examine the estimation reliability and error propagation of the model parameters. It was found that for all three model configurations examined the reliability of the CMRO estimate was dependent on the blood flow and oxygen extraction fraction in tissue (∼2% in tissues of high blood flow and normal extraction and 10% in tissues of low blood flow and low extraction fraction, in a study of 1 × 106 counts/brain slice in 3 min). The estimation reliability is drastically decreased if the total data collection time is reduced to 1 min but is not critically sensitive to the scan sampling interval used. Estimating blood flow or vascular volume simultaneously with CMRO will reduce the reliability of the CMRO estimate by ∼50%. Propagation of parameter error from blood flow or vascular volume to CMRO is dependent on the model configuration as well as the scanning schedule and estimation procedure used. Results from the study provide useful information for improving the study procedure of CMRO measurements. The present study also illustrates a general representation of PET measurements and an approach that can be applied to other tracer techniques in PET for selecting appropriate model configurations and for designing proper experimental procedures.

scholarly journals Assessment of MicroPET Image Quality Based on Reconstruction Methods and Post-Filtering

2021 ◽  
Vol 11 (18) ◽  
pp. 8707
Author(s):  
Hyeon-Sik Kim ◽  
Byeong-il Lee ◽  
Jae-Sung Ahn
Keyword(s):  
Image Quality ◽  
Volume Effect ◽  
Partial Volume Effect ◽  
Emission Tomography ◽  
Recovery Coefficient ◽  
Filtering Method ◽  
Reconstruction Methods ◽  
Positron Emission ◽  
Image Blurring ◽  
Selection Of

The accuracy of positron emission tomography (PET) imaging is hampered by the partial volume effect (PVE), which causes image blurring and sampling. The PVE produces spillover phenomena, making PET analysis difficult. Generally, the PVE values vary based on reconstruction methods and filtering. Thus, selection of the proper reconstruction and filtering method can ensure accurate and high-quality PET images. This study compared the values of factors (recovery coefficient (RC), uniformity, and spillover ratio (SOR)) associated with different reconstruction and post-filtering methods using a mouse image quality phantom (NEMA NU 4), and we present an effective approach for microPET images. The PET images were obtained using a microPET scanner (Inveon, Siemens Medical Solutions, Malvern, PA, USA). PET data were reconstructed and/or post-filtered. For tumors smaller than 3 mm, iterative reconstruction methods provided better image quality. For tumor sizes bigger than 3 mm, reconstruction methods without post-filtering showed better results.

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