A Cone-Shaped Phantom for Assessment of Small Animal PET Scatter Fraction and Count Rate Performance

Purpose: Positron emission tomography (PET) image quality deteriorates as the object size increases owing to increased detection of scattered and random events. The characterization of the scatter component in small animal PET imaging has received little attention owing to the small scatter fraction (SF) when imaging rodents. The purpose of this study is first to design and fabricate a cone-shaped phantom which can be used for measurement of object size-dependent SF and noise equivalent count rates (NECR), and second, to assess these parameters for two small animal PET scanners as function of radial offset, object size and lower energy threshold (LET). Methods: The X-PET™ and LabPET-8™ scanners were modeled as realistically as possible using GATE Monte Carlo simulation platform. The simulation models were validated against experimental measurements in terms of sensitivity, SF and NECR. The dedicated phantom was fabricated in-house using high-density polyethylene. The optimized dimensions of the cone-shaped phantom are 158mm (length), 20mm (minimum diameter), 70mm (maximum diameter) and taper angle of 9°. Results: The relative difference between simulated and experimental results for the LabPET-8™ scanner varied between 0.7% and 10% except for a few results where it was below 16%. Depending on the radial offset from the center of the central axial field-of-view (3-6cm diameter), the SF for the cone-shaped phantom varied from 26.3% to 18.2%, 18.6 to 13.1% and 10.1 to 7.6% for the X-PET™, whereas it varied from 34.4% to 26.9%, 19.1 to 17.0% and 9.1 to 7.3% for the LabPET-8™, for LETs of 250, 350 and 425keV, respectively. The SF increases as the radial offset decreases, LET decreases and object size increases. The SF is higher for the LabPET-8™ compared with the X-PET™ scanner. The NECR increases as the radial offset increases and object size decreases. The maximum NECR was obtained at a LET of 350keV for the LabPET-8™ and 250keV for the X-PET™. High correlation coefficients for SF and NECR were observed between the cone-shaped phantom and an equivalent volume cylindrical phantom for the three considered axial fields of view. Conclusions: A single cone-shaped phantom enables the assessment of the impact of three factors, namely radial offset, LET and object size on PET SF and count rate estimates. This phantom is more realistic owing to the non-uniform shape of rodents' bodies compared to cylindrical uniform phantoms and seems to be well suited for evaluation of object size-dependent SF and NEC

Congenital Diaphragmatic Hernia: A Major Challenge for Neonatologists

Congenital diaphragmatic hernia (CDH) is a major congenital anomaly of the neonates, characterized by the herniation of abdominal contents into the thoracic cavity during fetal life. This results in significant pulmonary hypertension and hypoxemia after birth, which responds poorly to therapeutic interventions. CDH is associated with high morbidity and mortality. The exact pathogenesis is not well understood, and genetic factors have been proposed. The management starts in utero, with antenatal diagnosis and identification of prenatal predictors for the outcomes, which help in the selection of cases suitable for fetal therapy. The postnatal management is complicated by the need for variable cardio-respiratory support and even extra corporeal membrane oxygenation (ECMO), before corrective surgery is undertaken. Improvement in the understanding of the pathophysiology of the underdeveloped lungs and pulmonary vessels has contributed to substantial progress in the management of CDH, which has translated into improved outcomes and survival. Still, many questions regarding CDH remain unanswered and the management is largely based on weak evidence

Neonatal screening for hypothyroidism by time - Resolved fluoroimmunoassay in Jharkhand

Objective: To screen newborns for congenital hypothyroidism by time resolved fluoroimmunoassay (TRFIA) (TRFIA meter by Perkin Elmer). Methods: Participants were randomly selected from the Department of Paediatrics/Obstetrics and Gynaecology, Rajendra Institute of Medical Sciences and Maternity Hospitals around 20 km of Rajendra Institute of Medical Sciences, Ranchi. Blood samples were obtained by heel prick for thyroid-stimulating hormone (TSH) estimation from newborns selected from abovementioned hospitals. Samples were collected from 3rd day of life to 7th day of life on a filter paper card and analyzed by TRFIAbased method. Results: 60% of the newborns were male and 40% were female among 150 newborns selected for study. Out ofthem, 65.33% were term, 28% were pre-term, and 6.67% were post-term. 92% newborns had TSH level <10 mIU/L, 8% had TSH between 10 and 20 mIU/L and none had TSH value >20 mIU/L. Conclusion: The prevalence of borderline TSH assay was 80/1000 newborns, which is significant. Screening studies for such conditions need larger sample size, stronger logistics to cover a larger area

Scatter Characterization and Correction for Simultaneous Multiple Small-Animal PET Imaging

Purpose: The rapid growth and usage of small-animal positron emission tomography (PET) in molecular imaging research has led to increased demand on PET scanner's time. One potential solution to increase throughput is to scan multiple rodents simultaneously. However, this is achieved at the expense of deterioration of image quality and loss of quantitative accuracy owing to enhanced effects of photon attenuation and Compton scattering. The purpose of this work is, first, to characterize the magnitude and spatial distribution of the scatter component in small-animal PET imaging when scanning single and multiple rodents simultaneously and, second, to assess the relevance and evaluate the performance of scatter correction under similar conditions. Methods: The LabPET™-8 scanner was modelled as realistically as possible using Geant4 Application for Tomographic Emission Monte Carlo simulation platform. Monte Carlo simulations allow the separation of unscattered and scattered coincidences and as such enable detailed assessment of the scatter component and its origin. Simple shape-based and more realistic voxel-based phantoms were used to simulate single and multiple PET imaging studies. The modelled scatter component using the single-scatter simulation technique was compared to Monte Carlo simulation results. PET images were also corrected for attenuation and the combined effect of attenuation and scatter on single and multiple small-animal PET imaging evaluated in terms of image quality and quantitative accuracy. Results: A good agreement was observed between calculated and Monte Carlo simulated scatter profiles for single- and multiple-subject imaging. In the LabPET™-8 scanner, the detector covering material (kovar) contributed the maximum amount of scatter events while the scatter contribution due to lead shielding is negligible. The out-of field-of-view (FOV) scatter fraction (SF) is 1.70, 0.76, and 0.11% for lower energy thresholds of 250, 350, and 400keV, respectively. The increase in SF ranged between 25 and 64% when imaging multiple subjects (three to five) of different size simultaneously in comparison to imaging a single subject. The spill-over ratio (SOR) increases with increasing the number of subjects in the FOV. Scatter correction improved the SOR for both water and air cold compartments of single and multiple imaging studies. The recovery coefficients for different body parts of the mouse whole-body and rat whole-body anatomical models were improved for multiple imaging studies following scatter correction. Conclusions: The magnitude and spatial distribution of the scatter component in small-animal PET imaging of single and multiple subjects simultaneously were characterized, and its impact was evaluated in different situations. Scatter correction improves PET image quality and quantitative accuracy for single rat and simultaneous multiple mice and rat imaging studies, whereas its impact is insignificant in single mouse imaging

A study on body mass index and its correlation with type 2 diabetes

Obesity and increases in body weight are among the most important risk factors for type 2 diabetes mellitus. Obesity contributes to the development of type 2 diabetes mellitus. Body mass index is also known as obesity index. Body mass index is a strong and independent risk factor for being diagnosed in cases of type 2 diabetes mellitus. There is a high risk of type 2 diabetes in those who have a higher body mass index. The present study has been done with the objective of finding correlation between BMI and type 2 diabetes

Correlation between thyroxin hormone level, bilirubin and uric acid in diabetic subjects

Background: Levels of thyroxin hormone along with T3, TSH and other markers such as uric acid, bilirubin and glucose are important in diagnosis and medical management of diabetes mellitus and thyroid disorder. Relationship between these parameters are important in both diabetes mellitus and Thyroid gland disease, as both disorders are increasing very fast in Indian population. Present study aimed to analyzed T3, T4, TSH, uric acid and bilirubin in Haroti Region of Jhalawar, Rajasthan in diabetic and non diabetic subjects.Methods: One hundred diabetes mellitus subjects and 100 healthy control subjects were analyzed for determination of thyroxin, T3, TSH, uric acid and bilirubin by commercial kit method.Results: One hundred subjects of diabetes mellitus between age 30-60 years male and female were analyzed. It was observed significantly T3 <0.001 T4 <0.001 TSH <0.001 bilirubin <0.01 in diabetic subjects and found to be significant when compared in both groups. However, uric acid level insignificant in both patients and control groups.Conclusions:This study demonstrated that thyroxin hormone with T3, TSH and bilirubin and uric acid, are important parameters and their values are significant when compared with healthy subjects in diabetes mellitus and thyroid disorder. 

Shoot regeneration in the genotypes of cauliflower

This article does not have an abstract

Disaster relief operations: past, present and future

The aim of the preface is to introduce the scope of this special issue (SI). We explain our editorial approach and summarise our findings based on articles included in this SI. Finally, we outline future research questions which stemmed out of the discussions of this SI

Sustainable supply chain management: framework and further research directions

This paper argues for the use of Total Interpretive Structural Modeling (TISM) in sustainable supply chain management (SSCM). The literature has identified antecedents and drivers for the adoption of SSCM. However, there is relatively little research on methodological approaches and techniques that take into account the dynamic nature of SSCM and bridge the existing quantitative/qualitative divide. To address this gap, this paper firstly systematically reviews the literature on SSCM drivers; secondly, it argues for the use of alternative methods research to address questions related to SSCM drivers; and thirdly, it proposes and illustrates the use of TISM and Cross Impact Matrix-multiplication applied to classification (MICMAC) analysis to test a framework that extrapolates SSCM drivers and their relationships. The framework depicts how drivers are distributed in various levels and how a particular driver influences the other through transitive links. The paper concludes with limitations and further research directions