Atténuation des interactions électromagnétiques entre le module de détection LabPET II et l’IRM

Les scanners TEP/IRM simultanés offrent une occassion unique d'examiner en même temps les propriétés anatomiques et fonctionnelles des tissus malins, tout en évitant l'incertitude des systèmes séquentiels de TEP/IRM. Cependant, le couplage électromagnétique entre les deux modalités constitue un défi important à relever. Ces interférences électromagnétiques entravent les performances du scanner et altèrent la qualité d'image de chaque modalité. Bien que les métaux possèdent d'excellentes propriétés de blindage contre les fréquences radioélectriques, ils ne constituent pas nécessairement une option de blindage appropriée pour modifier les champs magnétiques induisant des courants de Foucault dans les couches métalliques. En conséquence, il existe une demande considérable pour un nouveau matériau de protection et une approche originale pour retirer les pièces métalliques du champ de vision IRM. L’objectif de ce projet était d’initier les études en vue de la réalisation d’un scanner TEP/IRM simultané basé sur des modules de détection LabPET II hautement pixélisés afin d’obtenir une résolution spatiale millimétrique pour le cerveau humain et le chien. L'électronique LabPET II comprend des circuits intégrés à application spécifique dans lesquels le signal est numérisé à proximité de la photodiode à avalanche et offre un environnement moins sensible aux interférences électromagnétiques. Pour atteindre l'objectif principal, premièrement, l'effet du matériau métallique des modules de détection LabPET II sur les performances de la TEP et de l'IRM est examiné théoriquement. Les résultats confirment que les composants métalliques du module de détection LabPET II altèrent le champ magnétique, génèrent des courants de Foucault ce qui augmente leur température. Ensuite, les performances électroniques des modules de détection LabPET II sous l’influence de bobines d’IRM faites sur mesure sont examinées. La résolution en énergie et la résolution temporelle se détériorent en présence de bobines RF et de bobines à gradient en raison des perturbations électromagnétiques. Subséquemment, un module de détection LabPET II blindé par une fine couche de composite cuivre-argent est étudié, prouvant que le blindage contre les interférences électromagnétiques avec le composite rétablit les performances en TEP, fournissant moins d'induction par courants de Foucault. En outre, une nouvelle configuration de blindage basée sur un composite de couche flexible de nanotubes de carbone a été fabriquée pour limiter les interférences électromagnétiques. Les composites de nanotubes de carbone créent une couche hautement conductrice avec des chemins conducteurs minimaux, ce qui permet de réduire les courants de Foucault. Le principal résultat scientifique de ce projet est que le blindage composite empêche les interférences de basses et hautes fréquences et réduit l'induction de courants de Foucault, offrant ainsi la flexibilité nécessaire pour acquérir une séquence rapide de commutation de gradients. D'un point de vue technique, le module de détection LabPET II ainsi blindé présente une excellente performance dans un environnement de type IRM, ce qui permet de concevoir un insert TEP basé sur la technologie LabPET II.Abstract: Simultaneous PET/ MRI scanners provide a unique opportunity to investigate anatomical and functional properties of malignant tissues at the same time while avoiding the uncertainty of a sequential PET/MRI systems. However, electromagnetic coupling between the two modalities is a significant challenge that needs to be addressed. These electromagnetic interferences (EMI) hinder the performance of both scanners and distort the image quality of each modality. Although metals have excellent radio-frequency shielding properties, they are not necessarily an appropriate shielding option for altering magnetic fields that induce eddy currents in any metallic layer. Thus, there is a considerable demand for a new shielding material and an original approach to remove metallic parts from the MRI field of view. The objective of this project was to initiate the realization of a simultaneous PET/MRI scanner based on highly pixelated LabPET II detection modules to achieve millimeter spatial resolution for the human brain and dogs. The LabPET II electronics include application specific integrated circuits where the signal is digitized near the avalanche photodiode and offers an environment less susceptible to EMI. To fulfill the main aim, for the first time, the effect of the metallic material of LabPET II on PET and MRI performance was theoretically examined. Results confirm that metallic components of the LabPET II detection modules distort the magnetic field, generate eddy currents, and increase temperature. Then, the LabPET II electronics performance under the influence of custom-made MRI coils was investigated. Its energy and timing resolutions deteriorate in the presence of both RF and gradient signals because of EMIs. Thus, a LabPET II detection module shielded by a thin layer of the copper-silver composite was investigated, proving that shielding EMIs with the composite restores the PET performance, with less eddy current induction. Besides, a new shielding configuration based on a flexible layer of carbon nanotube (CNT) composite was fabricated to limit the EMIs. The CNT composite creates a highly conductive layer with minimal conductive paths that allows eddy currents to be decreased. The primary scientific outcome of this project is that the novel composite shielding rejects both low and high-frequency interferences and reduces eddy current induction, offering the flexibility to acquire a fast gradient switching sequence. From a technical point of view, the shielded LabPET II detection module demonstrates an excellent performance in an MRI-like environment supporting the feasibility of designing a PET-insert based on LabPET II technology

Association Between Metabolic Syndrome and Stroke: A Population Based Cohort Study

Both metabolic syndrome (MetS) and stroke are associated with increased risk of mortality. Here, we aimed to assess the prevalence of MetS among adults using three definitions (Adult Treatment Panel III (ATP-III), International Diabetes Federation (IDF) and IDF ethnic specific cut-off for Iranian criteria) and its association with stroke. We performed a cross-sectional study of a total of 9991 adult participants of Rafsanjan Cohort Study (RCS), as part of the Prospective epidemiological research studies in Iran (PERSIAN cohort study). The MetS prevalence was evaluated in participants according to the different criteria. Multivariate logistic regression analyses were conducted to assess the association between three definitions of MetS with stroke. We found that MetS was significantly associated with higher odds of stroke according to NCEP-ATP III (odds ratio (OR): 1.89, 95% confidence interval (CI) 1.30-2.74), international IDF (OR:1.66, 95% CI: 1.15-2.40) and Iranian IDF (OR:1.48, 95% CI: 1.04-2.09) after adjusted for variables confounders. Furthermore, after adjustment, in receiver operating characteristic (ROC) curve, the AUROC was 0.79 (95% CI = 0.75-0.82), 0.78(95% CI = 0.74-0.82) and 0.78(95% CI = 0.74-0.81) for presence of MetS according to NCEP-ATP III, international IDF and Iranian IDF, respectively. ROC analyses revealed that all of these three criteria for MetS are moderately accurate for the identification of increased stroke risk.In conclusion, our results showed that MetS was associated with increased odds of stroke. Our findings implicate the importance of early identification, treatment, and ultimately prevention of the metabolic syndrome

Atténuation des interactions électromagnétiques entre le module de détection LabPET II et l’IRM

Les scanners TEP/IRM simultanés offrent une occassion unique d'examiner en même temps les propriétés anatomiques et fonctionnelles des tissus malins, tout en évitant l'incertitude des systèmes séquentiels de TEP/IRM. Cependant, le couplage électromagnétique entre les deux modalités constitue un défi important à relever. Ces interférences électromagnétiques entravent les performances du scanner et altèrent la qualité d'image de chaque modalité. Bien que les métaux possèdent d'excellentes propriétés de blindage contre les fréquences radioélectriques, ils ne constituent pas nécessairement une option de blindage appropriée pour modifier les champs magnétiques induisant des courants de Foucault dans les couches métalliques. En conséquence, il existe une demande considérable pour un nouveau matériau de protection et une approche originale pour retirer les pièces métalliques du champ de vision IRM. L’objectif de ce projet était d’initier les études en vue de la réalisation d’un scanner TEP/IRM simultané basé sur des modules de détection LabPET II hautement pixélisés afin d’obtenir une résolution spatiale millimétrique pour le cerveau humain et le chien. L'électronique LabPET II comprend des circuits intégrés à application spécifique dans lesquels le signal est numérisé à proximité de la photodiode à avalanche et offre un environnement moins sensible aux interférences électromagnétiques. Pour atteindre l'objectif principal, premièrement, l'effet du matériau métallique des modules de détection LabPET II sur les performances de la TEP et de l'IRM est examiné théoriquement. Les résultats confirment que les composants métalliques du module de détection LabPET II altèrent le champ magnétique, génèrent des courants de Foucault ce qui augmente leur température. Ensuite, les performances électroniques des modules de détection LabPET II sous l’influence de bobines d’IRM faites sur mesure sont examinées. La résolution en énergie et la résolution temporelle se détériorent en présence de bobines RF et de bobines à gradient en raison des perturbations électromagnétiques. Subséquemment, un module de détection LabPET II blindé par une fine couche de composite cuivre-argent est étudié, prouvant que le blindage contre les interférences électromagnétiques avec le composite rétablit les performances en TEP, fournissant moins d'induction par courants de Foucault. En outre, une nouvelle configuration de blindage basée sur un composite de couche flexible de nanotubes de carbone a été fabriquée pour limiter les interférences électromagnétiques. Les composites de nanotubes de carbone créent une couche hautement conductrice avec des chemins conducteurs minimaux, ce qui permet de réduire les courants de Foucault. Le principal résultat scientifique de ce projet est que le blindage composite empêche les interférences de basses et hautes fréquences et réduit l'induction de courants de Foucault, offrant ainsi la flexibilité nécessaire pour acquérir une séquence rapide de commutation de gradients. D'un point de vue technique, le module de détection LabPET II ainsi blindé présente une excellente performance dans un environnement de type IRM, ce qui permet de concevoir un insert TEP basé sur la technologie LabPET II.Abstract: Simultaneous PET/ MRI scanners provide a unique opportunity to investigate anatomical and functional properties of malignant tissues at the same time while avoiding the uncertainty of a sequential PET/MRI systems. However, electromagnetic coupling between the two modalities is a significant challenge that needs to be addressed. These electromagnetic interferences (EMI) hinder the performance of both scanners and distort the image quality of each modality. Although metals have excellent radio-frequency shielding properties, they are not necessarily an appropriate shielding option for altering magnetic fields that induce eddy currents in any metallic layer. Thus, there is a considerable demand for a new shielding material and an original approach to remove metallic parts from the MRI field of view. The objective of this project was to initiate the realization of a simultaneous PET/MRI scanner based on highly pixelated LabPET II detection modules to achieve millimeter spatial resolution for the human brain and dogs. The LabPET II electronics include application specific integrated circuits where the signal is digitized near the avalanche photodiode and offers an environment less susceptible to EMI. To fulfill the main aim, for the first time, the effect of the metallic material of LabPET II on PET and MRI performance was theoretically examined. Results confirm that metallic components of the LabPET II detection modules distort the magnetic field, generate eddy currents, and increase temperature. Then, the LabPET II electronics performance under the influence of custom-made MRI coils was investigated. Its energy and timing resolutions deteriorate in the presence of both RF and gradient signals because of EMIs. Thus, a LabPET II detection module shielded by a thin layer of the copper-silver composite was investigated, proving that shielding EMIs with the composite restores the PET performance, with less eddy current induction. Besides, a new shielding configuration based on a flexible layer of carbon nanotube (CNT) composite was fabricated to limit the EMIs. The CNT composite creates a highly conductive layer with minimal conductive paths that allows eddy currents to be decreased. The primary scientific outcome of this project is that the novel composite shielding rejects both low and high-frequency interferences and reduces eddy current induction, offering the flexibility to acquire a fast gradient switching sequence. From a technical point of view, the shielded LabPET II detection module demonstrates an excellent performance in an MRI-like environment supporting the feasibility of designing a PET-insert based on LabPET II technology

Electrochemical Performance Improvement of the Catalyst of the Methanol Microfuel Cell Using Carbon Nanotubes

In this research, the electrocatalytic activity of platinum-ruthenium nanoparticles on carbon nanotubes and carbon black in methanol oxidation reaction has been investigated. Moreover, the electrochemical performance of a single passive direct methanol fuel cell run by these two different electrocatalysts has been reported. Physical characterization and electrochemical tests reveal the superiority of PtRu on carbon nanotubes. Based on the voltammetry outcomes, it was found that methanol oxidation reaction kinetics has been improved on the nanotube-supported catalyst. The current density of oxidation reaction has increased up to 62% in nanotube sample compared to carbon black-supported one. The electrochemical test results have shown that the carbon nanotubes increase the performance of the microfuel cell by 37% at maximum power density, compared to the carbon black. Moreover, the resistance of the samples supported by carbon nanotubes to poisonous intermediate species has been found 3% more than carbon black-supported one. According to the chronoamperometry test results, it was concluded that the performance and sustainability of the carbon nanotube electrocatalyst show a remarkable improvement compared to carbon black electrocatalyst in the long term

Comparison of serum levels of vitamin D in periodontitis patients with and without type 2 diabetes and healthy subjects

Abstract Objective The purpose of this study is to find out the levels of serum vitamin D in periodontitis patients with and without type 2 diabetes and to compare them with healthy subjects. Methods In this study, 48 periodontitis patients with type 2 diabetes mellitus (PDM), 53 periodontitis patients (P), and 42 controls who were in the age ranges of 30–50 years and had the entry requirements were selected. Plaque index, calculus index, modified gingival index, pocket depth, clinical attachment loss (CAL), and tooth loss were measured. Serum 25(OH)D level was estimated by electrochemiluminescence immunoassay, and fasting blood sugar and glycosylated hemoglobin were estimated by biochemical colorimetric assays. Results The mean serum 25(OH)D level was 17.06 ± 10.73, 15.12 ± 7.74, and 14.17 ± 11.04 ηg/ml for PDM, P, and control groups, respectively, showing no statistical difference. The mean CAL was significantly high in diabetic patients as compared to other groups. Prediabetes prevalence was significantly high in periodontitis patients as compared to controls. Conclusions The prevalence of vitamin D insufficiency was high in the population studied. Serum levels of 25(OH)D showed no significant difference between groups. Periodontitis patients showed an elevated risk for diabetes

Caregiving Appraisal in Family Caregivers of Older Adults

Objectives: With increasing the older adults’ population, the old age diseases increase, as well as older people’s dependency and need for care. This issue further highlights the importance of attention to family caregiving and experiences. Among the concepts related to family caregiving, the concept of selfappraisal of caregiver has a special role in acceptance, continuance, and outcomes of caregiving. This study aimed to review all aspects of caregiving appraisal concept in family caregivers. Methods & Materials: The current study is a review study. To examine the concept of family caregiver appraisal, all articles without time limitation were searched in databases of Google Scholar, ProQuest, Scopus, and PubMed with keywords of “appraisal,” “caregiving,” “family caregiving,” “burden,” “satisfaction,” “positive aspect,” “negative aspect,” “older adults,” and “elderly.” The Iranian databases of IranMedex, IranDoc, and SID were also searched with equivalent Persian Keywords. Results: Many factors such as social, cultural, and personal characteristics can influence the caregivers’ perception. This subjective appraisal makes caregivers not to perceive their conditions the same, in spite of stressful situation of caregiving. Some caregivers have positive experiences in this condition and some perceive stress more than what actually exist. This will create negative outcomes for the health and welfare of the caregivers. Conclusion: Caregiving appraisal is a multidimensional concept, which has positive and negative aspects. By taking into account all aspects of this concept, one can better understand and ultimately has a more comprehensive assessment of the status of caregivers, and implement effective interventions towards improving the health of this group

Analysis of the Psychometric Properties of the Perceived Social Support Scales in Older Adults

Objectives: An important part of health status assessment of older adults is measurement of their perceived social support. Choosing a sound scale with good psychometrics properties is a prerequisite for proper assessment. The aim of this review article was to analyze the psychometric properties of perceived social support scales to help researchers become more familiar with positive and negative aspects of these instruments and select a more valid and appropriate one. Methods & Materials: A comprehensive search of databases of Medline, Google scholar, and Scopus was conducted, using the keywords related to design and process of psychometrics scales of perceived social support. In this regard, the articles published from 1970 until 2014 were collected. Then, the psychometric properties of the selected scales, including validity, reliability, responsiveness, and interpretability were assessed using the COSMIN comprehensive checklist. Results: Most of the scales had not reported a complete and desirable psychometrics properties. Some of them, despite of being developed for adult populations, lacked the capability for using in older adults (length of scale, length of questions, special questions). Conclusion: The results revealed that despite the lack of an appropriate scale for measurement of old adults perceived social support, the MOS is the only scale which can be recommended to gerontologists until now. However, a vital need is felt for developing an instrument based on cultural and social characteristics of different societies with acceptable psychometrics properties for measuring perceived social support in older adults

Association between metabolic syndrome and stroke: a population based cohort study

Abstract Both metabolic syndrome (MetS) and stroke are associated with increased risk of mortality. Here, we aimed to assess the prevalence of MetS among adults using three definitions (Adult Treatment Panel III (ATP-III), International Diabetes Federation (IDF) and IDF ethnic specific cut-off for Iranian criteria) and its association with stroke. We performed a cross-sectional study of a total of 9991 adult participants of Rafsanjan Cohort Study (RCS), as part of the Prospective epidemiological research studies in Iran (PERSIAN cohort study). The MetS prevalence was evaluated in participants according to the different criteria. Multivariate logistic regression analyses were conducted to assess the association between three definitions of MetS with stroke. We found that MetS was significantly associated with higher odds of stroke according to NCEP-ATP III (odds ratio (OR): 1.89, 95% confidence interval (CI) 1.30–2.74), international IDF (OR:1.66, 95% CI: 1.15–2.40) and Iranian IDF (OR:1.48, 95% CI: 1.04–2.09) after adjusted for variables confounders. Furthermore, after adjustment, in receiver operating characteristic (ROC) curve, the AUROC was 0.79 (95% CI = 0.75–0.82), 0.78(95% CI = 0.74–0.82) and 0.78(95% CI = 0.74–0.81) for presence of MetS according to NCEP-ATP III, international IDF and Iranian IDF, respectively. ROC analyses revealed that all of these three criteria for MetS are “moderately accurate” for the identification of increased stroke risk. In conclusion, our results showed that MetS was associated with increased odds of stroke. Our findings implicate the importance of early identification, treatment, and ultimately prevention of the metabolic syndrome

The association between subclinical hypothyroidism and exacerbation in patients with chronic obstructive pulmonary disease

This study aimed to investigate the association between subclinical hypothyroidism and exacerbation in patients with chronic obstructive pulmonary disease (COPD). This descriptive-analytical study was performed on patients with COPD that were diagnosed by spirometry and GOLD guides. A modified medical research council (mMRC) questionnaire was also used for grading dyspnea. The severity of the disease was determined according to the GOLD criteria. Patients were divided into mild, moderate, severe, and very severe COPD. Then, the patients were included in high-risk (C and D) and low-risk (A and B) groups. Thyroid-stimulating hormone (TSH), free thyroxine, triiodothyronine (T3), and T3 resin uptake tests were assessed. Out of 119 patients with COPD, about 74.8% were males and 25.2% were females. Overall, 50.4% of participants were in an exacerbation state and 49.6% were stable. A significant association was reported between the number and years of cigarette smoking and the exacerbation of COPD (P0.05). There was a significant association between severity in exacerbation and stable groups (P 0.05). The frequency of dyspnea grade with high mMRC scores in the exacerbation group was higher than in the stable group. The mean difference in FEV1, FVC, FEV1/FVC, and T3 variables was significant between the two studied groups. There was a significant difference between the variables of "one-year hospitalization", "one-year exacerbation" and "duration of illness" among the two groups of stable and exacerbation (P0.05). It’s suggested that the mean level of T3 could be used in the future to predict disease exacerbation in COPD.