| viXra.org > Quantitative Biology > 2004 |
 |
 |
| viXra.org > Quantitative Biology > 2004 |
|
|
[13] viXra:2004.0700 [pdf] replaced on 2020-05-02 17:03:56
Authors: Valdir Monteiro dos Santos Godoi
Comments: 2 Pages.
We asked the question of when an entire population will have been infected by the coronavirus, in this COVID-19 pandemic, assuming that no vaccination or other form of preventive (or curative) medication exists until that day, and the population remains constant (births and deaths are not accounted for). We also assume that no change in social behavior occurs until that date.
Category: Quantitative Biology
[12] viXra:2004.0601 [pdf] replaced on 2020-04-26 19:27:48
Authors: Valdir Monteiro dos Santos Godoi
Comments: 3 Pages.
The objective of this paper is to introduce a study relative a mathematical modeling of coronavirus contamination, knowing some current numbers first, by COVID-19 pandemic.
Category: Quantitative Biology
[11] viXra:2004.0599 [pdf] replaced on 2020-04-26 19:08:44
Authors: Valdir Monteiro dos Santos Godoi
Comments: 2 Pages.
The objective of this paper is to initiate a study relative a mathematical modeling of coronavirus contamination, knowing firstly some current numbers, given by COVID-19 pandemic.
Category: Quantitative Biology
[10] viXra:2004.0577 [pdf] submitted on 2020-04-24 14:59:59
Authors: Calogero Rinzivillo, Sergio Conte, Ferda Kaleagasioglu, Fang Wang, Alberto Foletti, Cengiz Morderniz, Elio Conte
Comments: 4 Pages.
We estimate the contagions of Sars-Covid-19 in Italy until June 2020 and we compare the results with our previous estimations. We obtain that the fractal model we use, estimates the behavior of the experimental data and prediction with an r2 value of 0.95. We have that the time of peak is 37.80 days for the prediction 1 and 37.33 days for prediction 2 starting with February 20. The number of contagions will drop below 10 in June 28 for prediction 1 and July 14 for prediction 2 as explained in Figure 1.
Category: Quantitative Biology
[9] viXra:2004.0540 [pdf] submitted on 2020-04-22 13:32:44
Authors: Piotr Slonka
Comments: 27 Pages.
Background (words 199/200)
We aimed to establish the observer repeatability and interscan reproducibility of
coronary 18F-sodium fluoride (18F-NaF) positron emission tomography (PET) uptake
using a novel semi-automated approach, coronary microcalcification activity (CMA).
Methods
Patients with multivessel coronary artery disease underwent repeated hybrid PET and
computed tomography angiography (CTA) imaging (PET/CTA). CMA was defined as
the integrated standardized uptake values (SUV) in the entire coronary tree exceeding 2
standard deviations above the background SUV. Coefficients of repeatability between
the same observer (intraobserver repeatability), between 2 observers (interobserver
repeatability) and coefficient of reproducibility between 2 scans (interscan
reproducibility), were determined at both vessel and patient level.
Results
In 19 patients, CMA was assessed twice in 43 coronary vessels on two PET/CT scans
performed 12±5 days apart. There was excellent intraclass correlation on a per-vessel
and per-patient level for intraobserver and interobserver repeatability as well as
interscan reproducibility (≥0.991 for all). There was 100% intraobserver, interobserver
and interscan agreement for the presence (CMA>0) or absence (CMA=0) of
coronary18F-NaF uptake. Mean CMA was 3.12±0.62 with coefficients of repeatability of
≤10% for all measures: intraobserver 0.24 and 0.22, interobserver 0.30 and 0.29 and
interscan 0.33 and 0.32 at a per-vessel and per-patient level respectively.
Conclusions
CMA is a repeatable and reproducible global measure of coronary atherosclerotic
activity.
Category: Quantitative Biology
[8] viXra:2004.0539 [pdf] submitted on 2020-04-22 13:35:42
Authors: Piotr Slomka
Comments: 22 Pages.
Purpose
To evaluate the impact of a respiratory averaged computed tomography attenuation
correction (RACTAC) instead of a standard single-phase computed tomography (CT)
attenuation correction (CTAC) map on the quantitative measures of coronary 18F-NaF
uptake in PET/CT.
Methods
This study comprised 23 patients who underwent 18F-NaF coronary PET in a hybrid
PET/CT system, employing 18F-NaF (250MBq). All patients had two CT scans, a standard
single-phase CTAC obtained during free-breathing, and a 4D cine-CT scan. From the
Cine-CT acquisition, RACTAC maps were obtained by averaging all images acquired
over 5 seconds. Two PET reconstruction protocols, one employing CTAC and another
employing RACTAC for attenuation correction were considered in this study. Following
reconstruction, the quantitative impact of employing RACTAC was assessed using
maximum target-to-background (TBRMAX) and coronary microcalcification activity (CMA).
Statistical differences were analyzed using reproducibility coefficients and Bland-Altman
plots.
Results
In 23 patients, we evaluated 34 coronary lesions using PET reconstructions utilizing
CTAC and RACTAC. There was good agreement between CTAC and RACTAC PET
reconstructions for TBRMAX (median [Interquartile range, IQR]: CTAC = 1.65[1.23-2.38],
RACTAC = 1.63[1.23-2.33], p=0.55), with coefficient of reproducibility of 0.18. The CMA
agreement was similar (median [IQR]: CTAC = 0.10 [0-1.0], RACTAC= 0.15[0-1.03],
p=0.55 with coefficient of reproducibility of 0.17
Conclusion
Employing RACTAC maps does not affect the quantification of the coronary 18F-NaF
uptake on PET/CT.
Category: Quantitative Biology
[7] viXra:2004.0489 [pdf] submitted on 2020-04-20 14:17:27
Authors: AlJaroudi, Wael; Hage, Fadi
Comments: 6 Pages.
Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome
coronavirus 2 (SARS-CoV-2), has been declared a pandemic with devastating effects on the
entire world. Madjid et al. from the University of Texas Health Science, Houston, Texas review
current information on the virus and COVID-19 and its effects on the cardiovascular system.
Coronaviruses, classified in 4 groups, were first identified in humans in the 1960s with 4 types
(all from the α and β classes) are endemic in humans usually causing mild and self-limiting
upper respiratory infections accounting for 15-30% of common colds. Both SARS (caused by
SARS-CoV) and Middle East respiratory syndrome (MERS, caused by MERS-CoV) caused
outbreaks (in 2002 and 2012, respectively) that had higher fatality rates but were much less
widespread than COVID-19. SARS-CoV-2 is genetically more similar to SARS-CoV (82%) than
MERS-CoV (50%). The virus has a mean incubation period of 5.2 days (95%CI, 4.1-7.0 days),
with the 95th percentile of the distribution at 12.5 days according to one study and up to 14 days
according to another. The World Health Organization reported a global mortality rate of 3.4%
but importantly, this rate varies by location, intensity of transmission, variations of care,
presence of comorbidities (including cardiovascular disease), advanced age, and likely other
factors. The primary symptoms of COVID-19 are fever, cough, and shortness of breath. Acute
cardiac injury determined by elevated high-sensitivity troponin levels is commonly observed in
severe cases and is strongly associated with mortality, complications such as acute respiratory
distress syndrome, arrhythmia, renal injury, and coagulopathy. There has been reported cases of
viral infiltration of the myocardium causing myocarditis. Myocardial injury can also be caused
by ischemia. It is important to note that COVID-19 in addition to inducing new cardiac
pathologies (such as myocarditis) may also exacerbate pre-existing cardiovascular disease.
Finally, some of the investigational therapies for COVID-19 may have cardiovascular effects.
Current treatment, until investigational therapies have been shown to be effective, is supportive
care and treatment of complications. The article offers a wonderful review of current knowledge
on COVID-19 as well as a review of SARS and MERS which provide further insights on the
effects of coronaviruses on the cardiovascular system.
Category: Quantitative Biology
[6] viXra:2004.0488 [pdf] submitted on 2020-04-20 14:49:57
Authors: Fanghu Wang, Weiping Xu, Wenbing Lv, Dongyang Du, Hui Feng, Xiaochun Zhang, Shuxia Wang, Wufan Chen, Lijun Lu
Comments: 14 Pages.
Background. To investigate the diagnostic value of joint PET myocardial perfusion and metabolic imaging for vascular stenosis in patients with suspected obstructive coronary artery disease (CAD).
Methods. Eighty-eight patients (53 and 35 applied for training and validation, respectively) with suspected obstructive CAD were referred to 13N-NH3 PET/CT myocardial perfusion imaging (MPI) and 18F-FDG PET/CT myocardial metabolic imaging (MMI) with available coronary angiography for analysis. One semi-quantitative indicator summed rest score (SRS) and five quantitative indicators, namely, perfusion defect extent (EXT), total perfusion deficit (TPD), myocardial blood flow (MBF), scar degree (SCR), and metabolism-perfusion mismatch (MIS), were extracted from the PET rest MPI and MMI scans. Different combinations of indicators and seven machine learning methods were used to construct diagnostic models. Diagnostic performance was evaluated using the sum of four metrics (noted as sumScore), namely, area under the receiver operating characteristic curve (AUC), accuracy, sensitivity, and specificity.
Results. In univariate analysis, MIS outperformed other individual indicators in terms of sumScore (2.816–3.042 vs. 2.138–2.908). In multivariate analysis, support vector machine (SVM) consisting of three indicators (MBF, SCR, and MIS) achieved the best performance (AUC 0.856, accuracy 0.810, sensitivity 0.838, specificity 0.757, and sumScore 3.261). This model consistently achieved significantly higher AUC compared with the SRS method for four specific subgroups (0.897, 0.833, 0.875, and 0.949 vs. 0.775, 0.606, 0.713, and 0.744; p=0.041, 0.005, 0.034 0.003, respectively).
Conclusions. The joint evaluation of PET rest MPI and MMI could improve the diagnostic performance for obstructive CAD. The multivariate model (MBF, SCR, and MIS) combined with SVM outperformed other methods.
Category: Quantitative Biology
[5] viXra:2004.0487 [pdf] submitted on 2020-04-20 14:57:40
Authors: Ali Ahmadi, Ran Klein, Howard C Lewin, Rob S.B. Beanlands, Robert A. deKemp
Comments: 28 Pages.
Introduction. Strontium-82/Rubidium-82 (82Sr/82Rb) generators are used widely for positron emission tomography (PET) imaging of myocardial perfusion. In this study, the 82Rb isotope yield and production efficiency of two FDA-approved 82Sr/82Rb generators were compared.
Methods. N=515 sequential daily quality assurance (QA) reports from 9 CardioGen-82® and 9 RUBY-FILL® generators were reviewed over a period of 2 years. A series of test elutions was performed at different flow-rates on the RUBY-FILL® system to determine an empirical correction-factor used to convert CardioGen-82® daily QA values of 82Rb activity (dose-calibrator ‘maximum’ of 50 mL elution at 50 mL/min) to RUBY-FILL® equivalent values (integrated ‘total’ of 35 mL elution at 20 mL/min). The generator yield (82Rb) and production efficiency (82Rb yield / 82Sr parent activity) were measured and compared after this conversion to a common scale.
Results. At the start of clinical use, the system reported 82Rb activity from daily QA was lower for CardioGen-82® vs RUBY-FILL® (2.3 ± 0.2 vs 3.0 ± 0.2 GBq, p<0.001) despite having similar 82Sr activity. Dose-calibrator ‘maximum’ (CardioGen-82®) values were found to under-estimate the integrated ‘total’ (RUBY-FILL®) activity by ~24% at 50 mL/min. When these data were used to convert the CardioGen-82 values to a common measurement scale (integrated total activity) the CardioGen-82® efficiency remained slightly lower than the RUBY-FILL® system on average (88 ± 4% vs 95 ± 4%, p<0.001). The efficiency of 82Rb production improved for both systems over the respective periods of clinical use.
Conclusions. 82Rb generator yield was significantly under-estimated using the CardioGen-82® vs RUBY-FILL® daily QA procedure. When generator yield was expressed as the integrated total activity for both systems, the estimated 82Rb production efficiency of the CardioGen-82® system was ~7% lower than RUBY-FILL® over the full period of clinical use.
Category: Quantitative Biology
[4] viXra:2004.0486 [pdf] submitted on 2020-04-20 15:01:12
Authors: S.S. Koenders, J.A. van Dalen, P.L. Jager, S. Knollema, JR Timmer, M. Mouden, C.H. Slump, J.D. van Dijk
Comments: 22 Pages.
Background: PET scanners using silicon photomultipliers with digital readout (SiPM PET) have an improved temporal and spatial resolution compared to PET scanners using conventional photomultiplier tubes (PMT PET). However, the effect on image quality and visibility of perfusion defects in myocardial perfusion imaging (MPI) is unknown. Our aim was to determine the value of a SiPM PET scanner in MPI.
Methods: We prospectively included 30 patients who underwent rest and regadenoson-induced stress Rubidium-82 (Rb-82) MPI on the D690 PMT PET (GE Healthcare) and within three weeks on the Vereos SiPM PET (Philips Healthcare). Two expert readers scored the image quality and assessed the existence of possible defects. In addition, interpreter’s confidence, myocardial blood flow (MBF) and myocardial flow reserve (MFR) values were compared.
Results: Image quality improved (p=0.03) using the Vereos as compared to the D690. Image quality of the Vereos and the D690 was graded fair in 20% and 10%, good in 60% and 50%, and excellent in 20% and 40%, respectively. Defect interpretation and interpreter’s confidence did not differ between the D690 and the Vereos (p>0.50). There were no significant differences in rest MBF (p≥0.29), stress MBF (p≥0.11) and MFR (p≥0.51).
Conclusion: SiPM PET provides an improved image quality in comparison to PMT PET. Defect interpretation, interpreter’s confidence and absolute blood flow measurements were comparable between both systems. SiPM PET is therefore a reliable technique for MPI using Rb-82.
Category: Quantitative Biology
[3] viXra:2004.0477 [pdf] submitted on 2020-04-20 05:49:26
Authors: Calogero Rinzivillo, Sergio Conte, Ferda Kaleagasioglu, Alberto Foletti, Cengiz Morderniz, Maria Pieralice, Elio Conte
Comments: 5 Pages.
We compute the factor R0(t) by using the SIR model in Italy and its some regional countries. We find that it is descending to a minimum value of 1.11 in Italy and respectively of 1.89, 1.86 and 3.13 for each region respectively
Category: Quantitative Biology
[2] viXra:2004.0146 [pdf] submitted on 2020-04-07 12:22:12
Authors: Calogero Rinzivillo, Sergio Conte, Ferda Kaleagasioglu, Fang Wang, Alberto Foletti, Elio Conte
Comments: 7 Pages.
We demonstrate that the SARS-CoV-2 is a multifractal and we study the implications of this discovery at
the basic level as well as when this structure is intended for its function and when it could be used for test in the
clinical applications depending the area of the singularity spectrum of the inspected virus and the other its
characterizing parameters in each clinical case from the virulence of the virus.
Category: Quantitative Biology
[1] viXra:2004.0089 [pdf] submitted on 2020-04-04 18:00:12
Authors: Vincenzo Nardozza
Comments: 3 Pages.
We propose a method for evaluating the number of asymptomatics in a COVID-19 Outbreak. The method will give only a lower bound for the real number.
Category: Quantitative Biology
| Third-Party Links: |
|