scholarly journals Effect of Normalization of Hematocrit on Brain Circulation and Metabolism in Hemodialysis Patients

1999 ◽  
Vol 10 (4) ◽  
pp. 854-863
Author(s):  
GEORGE METRY ◽  
BJÖRN WIKSTRÖM ◽  
SVEN VALIND ◽  
BO SANDHAGEN ◽  
TORBJÖRN LINDE ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Blood Flow ◽  
Brain Tissue ◽  
Blood Viscosity ◽  
Plasma Viscosity ◽  
Emission Tomography ◽  
Whole Blood Viscosity ◽  
Positron Emission ◽  
Healthy Control ◽  
The Brain

Abstract. Full correction of anemia with recombinant human erythropoietin (rhEPO) has been reported to reduce the risk of cardiovascular morbidity and mortality and improve the quality of life in hemodialysis (HD) patients. Effects of normalization of hematocrit on cerebral blood flow and oxygen metabolism were investigated by positron emission tomography. Regional cerebral blood flow (rCBF), cerebral blood volume (rCBV), oxygen extraction ratio (rOER), and metabolic rate for oxygen (rCMRO2) were measured in seven HD patients before and after correction of anemia and compared with those in six healthy control subjects. In addition, blood rheology before and on rhEPO therapy was measured in HD patients, which included blood viscosity, plasma viscosity, erythrocyte fluidity, and erythrocyte aggregability. The results showed that plasma viscosity was high (1.51 ± 0.19 mPa · s) and erythrocyte fluidity was low (85.8 ± 4.8 Pa-1 · s-1), while whole blood viscosity was within the normal range (3.72 ± 0.38 mPa · s) before rhEPO therapy. After treatment, the hematocrit rose significantly from 29.3 ± 3.3 to 42.4 ± 2.2% (P < 0.001), accompanied by a significant increase in the whole blood viscosity to 4.57 ± 0.16 mPa · s, nonsignificant decrease in erythrocyte fluidity to 79.9 ± 7.4 mPa-1 · s-1 and nonsignificant change in plasma viscosity (1.46 ± 1.3 mPa · s). Positron emission tomography measurements revealed that by normalization of hematocrit, rCBF significantly decreased from 65 ± 11 to 48 ± 12 ml/min per 100 cm3 (P < 0.05). However, arterial oxygen content (caO2) significantly increased from 5.7 ± 0.7 to 8.0 ± 0.4 mmol/L (P < 0.0001), rOER of the hemispheres significantly increased from 44 ± 3 to 51 ± 6% (P < 0.05) and became significantly higher than healthy control subjects (P < 0.05). In addition, rCBV significantly increased from 3.5 ± 0.5 to 4.6 ± 0.6 ml/100 cc brain tissue. The results showed that oxygen supply to the brain tissue increased with normalization of hematocrit, but it was accompanied by increased oxygen extraction in the brain tissue. This may be assumed to be related to the decrease of erythrocyte velocity in the cerebral capillaries as a result of the decreased blood deformability and the increased plasma viscosity.

scholarly journals Cerebral [15O] Water Clearance in Humans Determined by Positron Emission Tomography: II. Vascular Responses to Vibrotactile Stimulation

1997 ◽  
Vol 17 (1) ◽  
pp. 73-79 ◽  
Author(s):  
Hitoshi Fujita ◽  
Ernst Meyer ◽  
David C. Reutens ◽  
Hiroto Kuwabara ◽  
Alan C. Evans ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Blood Flow ◽  
Emission Tomography ◽  
Mr Images ◽  
Vibrotactile Stimulation ◽  
Positron Emission ◽  
The Right ◽  
The Brain ◽  
Hand Area ◽  
Water Clearance

When used to measure blood flow, water leaves a residue in the vascular bed, which may contribute to the calculation of increased blood flow during functional activation of brain tissue. To assess the magnitude of this contribution with the two-compartment positron emission tomography (PET) method, we mapped the water clearance ( K1) of the brain as an index of cerebral blood flow (CBF) and the apparent vascular distribution of nonextracted H215O ( Vo). The latter map represented mainly the cerebral arterial and arteriolar volume. We also prepared subtraction maps (Δ K1, Δ Vo) of the response to vibrotactile stimulation of the fingertips of the right hand of six normal volunteers. Using magnetic resonance (MR) images of all subjects, the data were rendered into Talairach's stereotaxic coordinates and the averaged subtraction images (activation minus baseline) merged with the corresponding averaged MRI image. The Δ K1 map revealed the expected response in the primary sensory hand area; the Δ Vo response was located about 13 mm more anteriorly, close to the central fissure, most likely reflecting changes of the arteries feeding the primary sensory hand area. We conclude that cerebral perfusion and cerebrovascular responses to vibrotactile stimulation may occur in disparate locations that can be identified separately by using the two-compartment method.

scholarly journals PET and the multitracer concept in the study of neurodegenerative diseases

2015 ◽  
Vol 9 (4) ◽  
pp. 343-349 ◽  
Author(s):  
Henry Engler ◽  
Andres Damian ◽  
Cecilia Bentancourt
Keyword(s):  
Positron Emission Tomography ◽  
Molecular Imaging ◽  
Neurodegenerative Diseases ◽  
Brain Tissue ◽  
Neurodegenerative Disorders ◽  
Clinical Symptoms ◽  
Emission Tomography ◽  
Positron Emission ◽  
The Brain

ABSTRACT The complexity of the pathological reactions of the brain to an aggression caused by an internal or external noxa represents a challenge for molecular imaging. Positron emission tomography (PET) can indicate in vivo,anatomopathological changes involved in the development of different clinical symptoms in patients with neurodegenerative disorders. PET and the multitracer concept can provide information from different systems in the brain tissue building an image of the whole disease. We present here the combination of 18F-flourodeoxyglucose (FDG) and N-[11C-methyl]-L-deuterodeprenyl (DED), FDG and N-[11C-methyl] 2-(4'-methylaminophenyl)-6-hydroxybenzothiazole (PIB), PIB and L-[11C]-3'4-Dihydrophenylalanine (DOPA) and finally PIB and [15O]H2O.

scholarly journals Synthesis and evaluation of N-isopropyl-p-[11C]methylamphetamine as a novel cerebral blood flow tracer for positron emission tomography

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jun Toyohara ◽  
Norihiro Harada ◽  
Takeharu Kakiuchi ◽  
Hiroyuki Ohba ◽  
Masakatsu Kanazawa ◽  
...  
Keyword(s):  
Positron Emission Tomography ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Emission Tomography ◽  
Emission Computed Tomography ◽  
Normal Brain ◽  
Brain Uptake ◽  
Pet Tracer ◽  
Positron Emission ◽  
The Brain

Abstract Introduction Increases in fasting plasma glucose (PG) levels lead to a decrease in 2-deoxy-2-[18F]fluoro-d-glucose ([18F]FDG) uptake in the normal brain, especially in the precuneus, resulting in an Alzheimer’s disease (AD)-like uptake pattern. Therefore, patients with higher PG levels, such as those with diabetes, can be erroneously diagnosed with AD when positron emission tomography (PET) imaging is done using [18F]FDG, due to reduced uptake of [18F]FDG in the precuneus. To help avoid an erroneous diagnosis of AD due to differences in glucose metabolism, evaluating cerebral blood flow (CBF) in the brain is useful. However, current techniques such as single photon emission computed tomography (SPECT) and [15O]H2O PET have limitations regarding early diagnosis of AD because the images they produce are of low resolution. Here, we developed a novel CBF PET tracer that may be more useful than [18F]FDG for diagnosis of AD. Methods We synthesized and evaluated N-isopropyl-p-[11C]methylamphetamine ([11C]4) as a carbon-11-labeled analogue of the standard CBF SPECT tracer N-isopropyl-p-[123I]iodoamphetamine. Fundamental biological evaluations such as biodistribution, peripheral metabolism in mice, and brain kinetics of [11C]4 in non-human primates with PET with successive measurement of [15O]H2O were performed. Results [11C]4 was synthesized by methylation of the corresponding tributyltin precursor (2) with [11C]MeI in a palladium-promoted Stille cross-coupling reaction. The brain uptake of [11C]4 in mice peaked at 5–15 min after injection and then promptly decreased. Most radioactivity in the brain was detected in the unchanged form, although in the periphery, [11C]4 was rapidly metabolized to hydrophilic components. Acetazolamide (AZM) treatment significantly increased the brain uptake of [11C]4 without affecting the blood levels of radioactivity in mice. Preliminary kinetics analysis showed that the K1 of [11C]4 reflected regional CBF in a vehicle-treated monkey, but that the K1 did not reflect CBF in higher flow regions after AZM loading. Conclusion [11C]4 is a potential novel CBF PET tracer. Further validation studies are needed before [11C]4 can be used in humans.

scholarly journals Evaluation of [18F]-4-Fluoroantipyrine as a New Blood Flow Tracer for Multiradionuclide Autoradiography

1984 ◽  
Vol 4 (2) ◽  
pp. 259-263 ◽  
Author(s):  
Kazuhiro Sako ◽  
Mirko Diksic ◽  
Amami Kato ◽  
Y. Lucas Yamamoto ◽  
William Feindel
Keyword(s):  
Positron Emission Tomography ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Flow Measurement ◽  
Emission Tomography ◽  
Blood Flow Measurement ◽  
Local Cerebral Blood Flow ◽  
Positron Emission ◽  
The Brain ◽  
Flow Tracer

This article reports the evaluation of [18F]-4-fluoroantipyrine (FAP) as a quantitative blood flow tracer by comparing blood flow measured with [18F]FAP to that determined simultaneously with [14C]-4-iodoantipyrine (IAP), a standard blood flow tracer, by means of double-tracer autoradiography. The single-pass extraction value ( m), which indicates diffusibility of a tracer, was determined according to the procedure described by Crone. The diffusibility of FAP was essentially the same as that of IAP. The brain–blood partition coefficient for FAP was found to be similar to that for IAP, 0.89 ± 0.01. Values of local cerebral blood flow obtained with FAP agree with those determined with IAP. From these results, we concluded that FAP is indeed as good a blood flow tracer as IAP. Since 18F is a positron-emitting radionuclide, it might be a useful tracer for blood flow measurement by positron emission tomography.

scholarly journals Standardized Mean Regional Method for Calculating Global Positron Emission Tomographic Measurements

1985 ◽  
Vol 5 (3) ◽  
pp. 476-480 ◽  
Author(s):  
Joel S. Perlmutter ◽  
Peter Herscovitch ◽  
William J. Powers ◽  
Peter T. Fox ◽  
Marcus E. Raichle
Keyword(s):  
Positron Emission Tomography ◽  
Blood Flow ◽  
Blood Volume ◽  
Brain Region ◽  
Emission Tomography ◽  
Positron Emission Tomographic ◽  
Localization Technique ◽  
Positron Emission ◽  
Stereotactic Atlas ◽  
The Brain

A new “mean regional” method for calculating global hemispheric values of blood flow, blood volume, and metabolism with positron emission tomography is presented. It is based on a standardized set of regions defined according to coordinates in a stereotactic atlas of the brain. Region locations in each individual scan were determined by a localization technique that is independent of the appearance of the physiological images. Measurements obtained with this mean regional method minimize contributions from nonbrain structures such as ventricles or venous sinuses and provide the necessary basis for comparisons among different subjects and laboratories.

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