Effect of background activity of a net of excitatory neuron-like elements on conduction of excitation

1989 ◽  
Vol 19 (4) ◽  
pp. 301-309
Author(s):  
G. I. Shuvgina ◽  
V. N. Ponomarev ◽  
I. R. Rez'ova ◽  
A. A. Frolov
Keyword(s):  
Background Activity ◽  
Excitatory Neuron ◽  
Conduction Of Excitation

Quantitative Radioisotope Measurement of Duodenogastric Reflux in Patients with Ulcer or Gastrectomized for Ulcer

1985 ◽  
Vol 24 (03) ◽  
pp. 107-110
Author(s):  
M. Pääkkönen ◽  
S. Aukee ◽  
K. Korhonen ◽  
A. Pääkkönen ◽  
E. Länsimies ◽  
...  
Keyword(s):  
Gamma Camera ◽  
Background Activity ◽  
Bile Reflux ◽  
Duodenogastric Reflux ◽  
Upper Limit ◽  
Visual Evidence ◽  
Biochemical Measurement

SummaryIn this work the duodenogastric reflux was quantified as the amount of radioactivity entering the stomach after an i.v. administration of 99mmTc-HIDA in ulcer patients and in patients who had undergone BI gastrectomy. The results were compared with visual evidence of gastric activity in the gamma camera images and biochemical determination of gastric bile reflux. The method is useful in quantifying the reflux if the activity is above the background activity. It allows the determination of an upper limit for the reflux when the reflux is evident visually. Only two or three images are needed for the quantitation. No correlation was found between biochemical measurement of fasting bile reflux in the stomach and radioisotopic quantification.

Effects of background substraction on differential kidney function measured by static scintigraphy with DMSA and dynamic scintigraphy with MAG 3

2008 ◽  
Vol 47 (01) ◽  
pp. 43-47 ◽  
Author(s):  
A. Smokvina ◽  
S. Grbac Ivanković ◽  
V. Licul ◽  
N. Girotto
Keyword(s):  
Kidney Function ◽  
Background Subtraction ◽  
Background Activity ◽  
Ratio Method ◽  
Uptake Ratio ◽  
Kidney Size ◽  
Significant Difference ◽  
Laboratory Changes ◽  
Dynamic Scintigraphy

SummaryThe aim of this study was to assess the influence of background subtraction (BS) on estimation of differential kidney function (DF) on the static scintigraphy with 99mTc dimercaptosuccinic acid (DMSA) and dynamic scintigraphy with 99mTc mercaptoacetyltriglicine (MAG3) and to establish possible differences between DF values estimated with these methods. Patients, methods: Patients (n = 106) were selected among those scheduled to static and dynamic scintigraphies within 3 months, with no interim clinical and laboratory changes, regardless the kidney pathology. DF was estimated according to the uptake ratio method. Four background regions of interest (ROIs) were applied, identical for both studies, and DF values were recalculated after BS. The corrected values were compared to the values before correction, separately for DMSA and MAG3, and between the studies. The results showed that ROIs used introduce variable results for the same patients, predominantly when noncorrected DF values were <45%. There were no significant differences between DF values (corrected and noncorrected) obtained from static and dynamic scintigraphy in all groups of patients. Since numerous reasons can bring to the errors in DF estimation when BS is used, the conclusions are that it would probably be more accurate to avoid BS, particularly when DF values are compared in a patient follow-up, and when kidney function is normal. BS should be used, but always in the same way, only when there is a significant difference in kidney size, or when DF is <25%, since background activity is then considerable. MAG3 and DMSA can be equally used for DF estimation and their results compared in patient follow-up.

scholarly journals Novel FAP ligands enable improved imaging contrast in sarcoma patients due to FAPI-PET/CT

2021 ◽  
Author(s):  
Stefan A. Koerber ◽  
R. Finck ◽  
K. Dendl ◽  
M. Uhl ◽  
T. Lindner ◽  
...  
Keyword(s):  
Hybrid Imaging ◽  
Background Activity ◽  
The Novel ◽  
Malignant Tissue ◽  
Primary Tumors ◽  
Aggressive Disease ◽  
Standardized Uptake Values ◽  
Pet Ct ◽  
Pet Scans

Abstract Purpose A high expression of fibroblast activation protein (FAP) was observed in multiple sarcomas, indicating an enormous potential for PET/CT using 68Ga-radiolabeled inhibitors of FAP (FAPI). Therefore, this retrospective study aimed to evaluate the role of the novel hybrid imaging probe for sarcomas as a first clinical evaluation. Methods A cohort of 15 patients underwent 68Ga-FAPI-PET/CT for staging or restaging. The acquisition of PET scans was performed 60 min after administration of 127 to 308 MBq of the tracer. The uptake of 68Ga-FAPI in malignant tissue as well as in healthy organs was quantified by standardized uptake values SUVmean and SUVmax. Results Excellent tumor-to-background ratios (> 7) could be achieved due to low background activity and high SUVmax in primary tumors (median 7.16), local relapses (median 11.47), and metastases (median 6.29). The highest uptake was found for liposarcomas and high-grade disease (range 18.86–33.61). A high SUVmax (> 10) was observed for clinically more aggressive disease. Conclusion These preliminary findings suggest a high potential for the clinical use of 68Ga-FAPI-PET/CT for patients diagnosed with sarcoma.

scholarly journals Complexity analysis of the magnetoencephalogram background activity in Alzheimer's disease patients

2006 ◽  
Vol 28 (9) ◽  
pp. 851-859 ◽  
Author(s):  
Carlos Gómez ◽  
Roberto Hornero ◽  
Daniel Abásolo ◽  
Alberto Fernández ◽  
Miguel López
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Complexity Analysis ◽  
Background Activity

Variations in Skin Resistance and Their Relationship to G.S.R. Conditioning

1960 ◽  
Vol 106 (442) ◽  
pp. 281-287 ◽  
Author(s):  
Irene Martin
Keyword(s):  
Action Potentials ◽  
Background Activity ◽  
Skin Resistance ◽  
Muscle Action ◽  
Muscle Tonus ◽  
Experimental Procedure ◽  
Discontinuous Nature ◽  
The Subject ◽  
Neural Excitation ◽  
Set Up

Any particular system which is being conditioned is likely to maintain a certain level of background activity throughout the experimental procedure; either of a discontinuous nature, as, for example, with eyeblink, heart rate and respiratory cycle, or continuously, as in the case of basal skin resistance and muscle tonus. This background activity or level of arousal does not remain constant but usually varies in time, presumably as a result of underlying neural excitation or inhibition. It may increase throughout an experiment if the subject becomes highly motivated, as with the gradients of muscle action potentials observed by Bartoshuk (1955), or decrease, if the subject becomes more relaxed and familiar with the set-up, as Duffy and Lacey (1946) found with level of skin conductance.

scholarly journals Interictal electroencephalogram: sensibility in the diagnosis of epileptic seizures in childhood

2007 ◽  
Vol 13 (1) ◽  
pp. 17-20
Author(s):  
Raquel Rego ◽  
Paulo Breno Noronha Liberalesso ◽  
Mônica Jaques Spinosa ◽  
Simone Carreiro Vieira ◽  
Alaídes S. Fojo Olmos ◽  
...  
Keyword(s):  
Diagnostic Test ◽  
Epileptic Seizure ◽  
Background Activity ◽  
International System ◽  
Epileptic Seizures ◽  
Children's Hospital ◽  
The World ◽  
Pediatric Neurologist ◽  
Spike Wave ◽  
Abnormal Results

INTRODUCTION: It is currently estimated that more than 10 million children all over the world have epilepsy and the EEG is the most commonly used diagnostic test in the investigation of these patients. The aim of this study was to analyze the sensibility of the EEG in revealing abnormalities in children with the clinical hypothesis of an epileptic seizure. METHODS: Out of 970 EEGs obtained between April 2005 and August 2006 at Pequeno Príncipe Children's Hospital, Curitiba, PR, Brazil, 692 fit the criteria proposed (clinical hypothesis of an epileptic seizure after the evaluation of a pediatric neurologist). All EEGs were recorded digitally, with minimal duration of 20 minutes and electrodes positioned according to the International System 10-20. Neonates were excluded. RESULTS: Age ranged from 30 days to 16.5 years (mean of 6.4 years and median of 4.1 years), 403 were female (58.2%). Out of the 692 EEG included in the study, 281 (40.6%) yielded abnormal results, 96 (34.2%) with abnormalities of the background activity (disorganization and/or asymmetry) and 185 (65.8%) with epileptiform paroxysms. The sensibility of the EEG was 40.6%. Sharpe wave occurred in 77 cases (41.6%), spike in 21 (11.4%), polispike in 14 (7.6%), spike-wave in 17 (9.2%), polispike-wave in 24 (13.0%) and exams with discharges of more than one morphology in 32 (17.3%). CONCLUSION: Our data strengthen the concept that even though the diagnosis of epilepsy is clinical and based on the semiological description of the epileptic crisis, the EEG has a good sensibility when properly indicated.

Changes in the background activity of neurons of the central gray substance when serotonin is applied to it or its synthesis is blocked

1992 ◽  
Vol 24 (2) ◽  
pp. 107-114 ◽  
Author(s):  
A. I. Pilyavskii ◽  
V. A. Yakhnitsa ◽  
N. V. Bulgakova ◽  
Yu. P. Limanskii
Keyword(s):  
Background Activity ◽  
Central Gray
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