scholarly journals Standard MRI-based attenuation correction for PET/MRI phantoms: a novel concept using MRI-visible polymer

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Ivo Rausch ◽  
Alejandra Valladares ◽  
Lalith Kumar Shiyam Sundar ◽  
Thomas Beyer ◽  
Marcus Hacker ◽  
...  
Keyword(s):  
Attenuation Correction ◽  
Homogeneous Region ◽  
Cylindrical Shape ◽  
Measured Activity ◽  
Water Compartment ◽  
Phantom Studies ◽  
Novel Concept ◽  
The Individual ◽  
Different Diameters ◽  
Phantom Material

Abstract Background PET/MRI phantom studies are challenged by the need of phantom-specific attenuation templates to account for attenuation properties of the phantom material. We present a PET/MRI phantom built from MRI-visible material for which attenuation correction (AC) can be performed using the standard MRI-based AC. Methods A water-fillable phantom was 3D-printed with a commercially available MRI-visible polymer. The phantom had a cylindrical shape and the fillable compartment consisted of a homogeneous region and a region containing solid rods of different diameters. The phantom was filled with a solution of water and [18F]FDG. A 30 min PET/MRI acquisition including the standard Dixon-based MR-AC method was performed. In addition, a CT scan of the phantom was acquired on a PET/CT system. From the Dixon in-phase, opposed-phase and fat images, a phantom-specific AC map (Phantom MR-AC) was produced by separating the phantom material from the water compartment using a thresholding-based method and assigning fixed attenuation coefficients to the individual compartments. The PET data was reconstructed using the Phantom MR-AC, the original Dixon MR-AC, and an MR-AC just containing the water compartment (NoWall-AC) to estimate the error of ignoring the phantom walls. CT-based AC was employed as the reference standard. Average %-differences in measured activity between the CT corrected PET and the PET corrected with the other AC methods were calculated. Results The phantom housing and the liquid compartment were both visible and distinguishable from each other in the Dixon images and allowed the segmentation of a phantom-specific MR-based AC. Compared to the CT-AC PET, average differences in measured activity in the whole water compartment in the phantom of −0.3%, 9.4%, and −24.1% were found for Dixon phantom MR-AC, MR-AC, and NoWall-AC based PET, respectively. Average differences near the phantom wall in the homogeneous region were −0.3%, 6.6%, and −34.3%, respectively. Around the rods, activity differed from the CT-AC PET by 0.7%, 8.9%, and −45.5%, respectively. Conclusion The presented phantom material is visible using standard MR sequences, and thus, supports the use of standard, phantom-independent MR measurements for MR-AC in PET/MRI phantom studies.

F-18-FDG Positron Imaging in Oncological Patients: Gamma Camera Coincidence Detection versus Dedicated PET

1999 ◽  
Vol 38 (04) ◽  
pp. 108-114 ◽  
Author(s):  
H.-J. Kaiser ◽  
U. Cremerius ◽  
O. Sabri ◽  
M. Schreckenberger ◽  
P. Reinartz ◽  
...  
Keyword(s):  
Attenuation Correction ◽  
Spatial Resolution ◽  
Gamma Camera ◽  
Lesion Detection ◽  
Coincidence Detection ◽  
System Sensitivity ◽  
Oncological Patients ◽  
Phantom Studies ◽  
Pet System ◽  
Dedicated Pet

Summary Aim of the present study was to investigate the feasibility of 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) imaging in oncological patients with a dual head gamma camera modified for coincidence detection (MCD). Methods: Phantom studies were done to determine lesion detection at various lesion-to-background ratios, system sensitivity and spatial resolution. Thirty-two patients with suspected or known malignant disease were first studied with a dedicated full-ring PET system (DPET) applying measured attenuation correction and subsequently with an MCD system without attenuation correction. MCD images were first interpreted without knowledge of the DPET findings. In a second reading, MCD and DPET were evaluated simultaneously. Results: The phantom studies revealed a comparable spatial resolution for DPET and MCD (5.9 × 6.3 × 4.2 mm vs. 5.9 × 6.5 × 6.0 mm). System sensitivity of MCD was less compared to DPET (91 cps/Bq/ml/cmF0V vs. 231 cps/ Bq/ml/cmFOv). At a lesion-to-background ratio of 4:1, DPET depicted a minimal phantom lesion of 1.0 cm in diameter, MCD a minimal lesion of 1.6 cm. With DPET, a total of 91 lesions in 27 patients were classified as malignant. MCD without knowledge of DPET results revealed increased FDG uptake in all patients with positive DPET findings. MCD detected 72 out of 91 DPET lesions (79.1 %). With knowledge of the DPET findings, 11 additional lesions were detected (+12%). MCD missed lesions in six patients with relevance for staging in two patients. All lesions with a diameter above 18 mm were detected. Conclusion: MCD FDG imaging yielded results comparable to dedicated PET in most patients. However, a considerable number of small lesions clearly detectable with DPET were not detected by MCD alone. Therefore, MCD cannot yet replace dedicated PET in all oncological FDG studies. Further technical refinement of this new method is needed to improve image quality (e.g. attenuation correction).

scholarly journals In Vivo Bioavailability of Selenium in Selenium-Enriched Streptococcus thermophilus and Enterococcus faecium in CD IGS Rats

Antioxidants ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 463
Author(s):  
Gabriela Krausova ◽  
Antonin Kana ◽  
Marek Vecka ◽  
Ivana Hyrslova ◽  
Barbora Stankova ◽  
...  
Keyword(s):  
Glutathione Reductase ◽  
Enterococcus Faecium ◽  
Reductase Activity ◽  
Streptococcus Thermophilus ◽  
Heart Tissue ◽  
Sprague Dawley ◽  
Glutathione Reductase Activity ◽  
Novel Concept ◽  
The Individual

The selenium (Se) enrichment of yeasts and lactic acid bacteria (LAB) has recently emerged as a novel concept; the individual health effects of these beneficial microorganisms are combined by supplying the essential micronutrient Se in a more bioavailable and less toxic form. This study investigated the bioavailability of Se in the strains Enterococcus faecium CCDM 922A (EF) and Streptococcus thermophilus CCDM 144 (ST) and their respective Se-enriched forms, SeEF and SeST, in a CD (SD-Sprague Dawley) IGS rat model. Se-enriched LAB administration resulted in higher Se concentrations in the liver and kidneys of rats, where selenocystine was the prevalent Se species. The administration of both Se-enriched strains improved the antioxidant status of the animals. The effect of the diet was more pronounced in the heart tissue, where a lower glutathione reductase content was observed, irrespective of the Se fortification in LAB. Interestingly, rats fed diets with EF and SeEF had higher glutathione reductase activity. Reduced concentrations of serum malondialdehyde were noted following Se supplementation. Diets containing Se-enriched strains showed no macroscopic effects on the liver, kidneys, heart, and brain and had no apparent influence on the basic parameters of the lipid metabolism. Both the strains tested herein showed potential for further applications as promising sources of organically bound Se and Se nanoparticles.

Urinary Crystal Growth: Effect of Inhibitor Mixtures

1981 ◽  
Vol 61 (4) ◽  
pp. 487-491 ◽  
Author(s):  
P. G. Werness ◽  
Jan H. Bergert ◽  
Karen E. Lee
Keyword(s):  
Crystal Growth ◽  
Calcium Oxalate ◽  
Inhibitory Activity ◽  
Calcium Oxalate Monohydrate ◽  
Growth Effect ◽  
Growth Inhibitory ◽  
Growth Inhibitory Activity ◽  
Measured Activity ◽  
Normal Urine ◽  
The Individual

1. The crystal growth inhibitory activity of mixtures of known inhibitors and of mixtures of known inhibitors with normal urine was determined in calcium oxalate monohydrate and hydroxyapatite seeded crystal growth systems. 2. The inhibitory activity of the mixtures was compared with the measured activity of the individual components of the mixtures. All mixtures had inhibitory activity equal to the sum of the activities of their components, with the exception of RNA/urine mixtures in the calcium oxalate monohydrate system. 3. RNA/urine mixtures had inhibitory activity toward calcium oxalate monohydrate crystal growth which was less than would be predicted from the activity of the RNA and of the urine which were added. This reduced inhibitory activity was shown to be due probably to hydrolysis of RNA by the ribonuclease activity normally present in urine. 4. The results of these experiments make it possible to determine quantitatively the contribution of various naturally occurring urinary crystal growth inhibitors to the total measured inhibition observed in urine.

ELECTROLYTIC TRANSPORT THROUGH CYLINDRICAL ETCHED PORES IN POLYETHYLENE TEREPTHALATE TRACK-ETCHED MEMBRANE

2008 ◽  
Vol 22 (14) ◽  
pp. 1415-1421 ◽  
Author(s):  
SANJEEV KUMAR ◽  
S. K. CHAKARVARTI
Keyword(s):  
Electric Potential ◽  
Driving Force ◽  
Room Temperature ◽  
Cylindrical Shape ◽  
Pore Density ◽  
Appreciable Change ◽  
Cylindrical Pores ◽  
Different Diameters ◽  
Track Etched Membrane ◽  
Etched Membrane

In the present work, electrolytic transport phenomena is studied for different electrolytes ( LiCl , NaCl , KCl of different concentrations) at room temperature (25 ± 2° C ) through etched pores with different diameters having cylindrical shape in track-etched membranes of polyethylene terepthalate (PET) with pore density of the order of 106/cm2. Electric potential has been used as the driving force. It has been observed that electrolytic transport through pores is different for different electrolytes, depending strongly on size of cations and is independent of size of anions. In the case of cylindrical pores, there has not been found appreciable change in forward and backward resistances.

Determinants of arterial gas embolism after scuba diving

2012 ◽  
Vol 112 (1) ◽  
pp. 91-95 ◽  
Author(s):  
Marko Ljubkovic ◽  
Jaksa Zanchi ◽  
Toni Breskovic ◽  
Jasna Marinovic ◽  
Mihajlo Lojpur ◽  
...  
Keyword(s):  
Patent Foramen Ovale ◽  
Scuba Diving ◽  
Exercise Bout ◽  
Moderate Exercise ◽  
Foramen Ovale ◽  
Cardiac Septal Defects ◽  
Novel Concept ◽  
The Individual ◽  
The Right ◽  
Systemic Arteries

Scuba diving is associated with breathing gas at increased pressure, which often leads to tissue gas supersaturation during ascent and the formation of venous gas emboli (VGE). VGE crossover to systemic arteries (arterialization), mostly through the patent foramen ovale, has been implicated in various diving-related pathologies. Since recent research has shown that arterializations frequently occur in the absence of cardiac septal defects, our aim was to investigate the mechanisms responsible for these events. Divers who tested negative for patent foramen ovale were subjected to laboratory testing where agitated saline contrast bubbles were injected in the cubital vein at rest and exercise. The individual propensity for transpulmonary bubble passage was evaluated echocardiographically. The same subjects performed a standard air dive followed by an echosonographic assessment of VGE generation (graded on a scale of 0–5) and distribution. Twenty-three of thirty-four subjects allowed the transpulmonary passage of saline contrast bubbles in the laboratory at rest or after a mild/moderate exercise, and nine of them arterialized after a field dive. All subjects with postdive arterialization had bubble loads reaching or exceeding grade 4B in the right heart. In individuals without transpulmonary passage of saline contrast bubbles, injected either at rest or after an exercise bout, no postdive arterialization was detected. Therefore, postdive VGE arterialization occurs in subjects that meet two criteria: 1) transpulmonary shunting of contrast bubbles at rest or at mild/moderate exercise and 2) VGE generation after a dive reaches the threshold grade. These findings may represent a novel concept in approach to diving, where diving routines will be tailored individually.

scholarly journals Simulation Analysis of Combined Flow over and under Semi-Cylindrical Structure

2019 ◽  
Vol 27 (2) ◽  
pp. 39-49
Author(s):  
Shaker Abdulatif Jalil
Keyword(s):  
Separation Zone ◽  
Simulation Analysis ◽  
Cylindrical Shape ◽  
Flow Profile ◽  
Combined Flow ◽  
Weir Flow ◽  
Total Head ◽  
Measured Flow ◽  
Discharge Simulation ◽  
Different Diameters

Combined flow over and under structure may solve the problem of the deposit of suspension materials in channels. Semi-cylindrical shape reduces the curvature of streamlines which reflected on its performance. To study how this shape performs, experimental and simulation has been done. The laboratory models were of four different diameters and four different gate openings. The same physical structures have been modeled in commercial software, FLOW-3D®, by employing RNG k- ε turbulence model. The verification has been based on measured flow profile and discharge. Simulation outputs indicate that a separation zone located at a distance from the structure became farther when the diameter and gate opening decreases, also the separation portions and their thickness are related to the incoming discharge.  The location height of separation zone tends to be lower when there is an increase in flow discharge and it is located at half the total depth when two flow portions are equal. The weir flow in this system shows a better performance than traditional weir by at least 33%, while the gate out flow is less than free flow of the same total head by 70% to 90%. Within the limitation of this work, two mathematical models for predicting discharge coefficient have been proposed for the weir and gate respectively, moreover a model for predicting relative discharge of weir to gate, and one mathematical model for the dimensionless total discharge.

scholarly journals Application of Visagism Concept to Assess the Co-Relation between the Temperament and Smile Esthetics: A Clinical Study

2021 ◽  
pp. 1-5
Author(s):  
Poorvi Jain ◽  
Surekha Godbole ◽  
Seema Sathe Kambala ◽  
Chetan Mahatme
Keyword(s):  
Digital Camera ◽  
Computer Assisted ◽  
Maximum Score ◽  
Validated Questionnaire ◽  
Wide Range ◽  
The Face ◽  
The Subject ◽  
Novel Concept ◽  
The Individual ◽  
Smile Esthetics

Background: Ability of a person to express a wide range of emotions with the movement of teeth and lips is called as a smile. Dentogenic concept considers gender, personality, age in harmonizing shapes of teeth with the face. Personality is unique for an individual. Unveiling personality traits, desires of the individual, translating them into natural tooth shapes to maintain the psychodentofacial harmony poses a major challenge to the clinician in designing a smile. Visagism is a novel concept that helps the dentists in providing restorations that involve esthetics psychological and social features of the created image, which influences the individual’s emotions. It involves the customization of an image. Aim and Objectives: To assess the co-relation between the smile esthetics and mental temperaments or personalities through the application of the concept of visagism. Methodology: A Digital camera (DSLR) for capturing the photographs and smile designing software will be used. Each subject will be instructed to occlude the teeth while capturing photographs. A validated questionnaire study will be conducted that will help to discover temperament of the subject. The answers will be evaluated and maximum score of the responses out of the list will be dominant temperament in that individual. Expected Outcome: Co-relation between this study might help clinicians to accurately assess the correlation between the temperament and the smile esthetics and eventually develop proper customisation of a smile with respect to the personality of the patient. Conclusion: If computer-assisted smile design and application of visagism concept would be accurate and reproducible, this might help and improve the planning of smile designing, the oral rehabilitations.

Breast Cancer Diagnosis Using Optimized Attribute Division in Modular Neural Networks

2013 ◽  
pp. 34-47
Author(s):  
Rahul Kala ◽  
Anupam Shukla ◽  
Ritu Tiwari
Keyword(s):  
Breast Cancer ◽  
Neural Network ◽  
Neural Networks ◽  
Genetic Algorithms ◽  
Cancer Diagnosis ◽  
Breast Cancer Diagnosis ◽  
Optimal Distribution ◽  
Modular Neural Networks ◽  
Novel Concept ◽  
The Individual

The complexity of problems has led to a shift toward the use of modular neural networks in place of traditional neural networks. The number of inputs to neural networks must be kept within manageable limits to escape from the curse of dimensionality. Attribute division is a novel concept to reduce the problem dimensionality without losing information. In this paper, the authors use Genetic Algorithms to determine the optimal distribution of the parameters to the various modules of the modular neural network. The attribute set is divided into the various modules. Each module computes the output using its own list of attributes. The individual results are then integrated by an integrator. This framework is used for the diagnosis of breast cancer. Experimental results show that optimal distribution strategy exceeds the well-known methods for the diagnosis of the disease.

scholarly journals Diameter-Controllable Magnetic Properties of Co Nanowire Arrays by Pulsed Electrodeposition

2010 ◽  
Vol 2010 ◽  
pp. 1-4 ◽  
Author(s):  
Youwen Yang ◽  
Yanbiao Chen ◽  
Yucheng Wu ◽  
Xiangying Chen ◽  
Mingguang Kong
Keyword(s):  
Magnetic Properties ◽  
Crystal Structures ◽  
Magnetization Reversal ◽  
Nanowire Arrays ◽  
Cylindrical Shape ◽  
Perpendicular Anisotropy ◽  
Alumina Membranes ◽  
Pulsed Electrodeposition ◽  
Different Diameters ◽  
Co Nanowires

The Co nanowires with different diameters were prepared by pulsed electrodeposition into anodic alumina membranes oxide templates. The micrographs and crystal structures of nanowires were studied by FE-SEM, TEM, and XRD. Due to their cylindrical shape, the nanowires exhibit perpendicular anisotropy. The coercivity and loop squareness (Mr/Ms) of Co nanowires depend strongly on the diameter. Both coercivity and Mr/Ms decrease with increasing wire diameter. The behavior of the nanowires is explained briefly in terms of localized magnetization reversal.

scholarly journals Comparison of Eight Methods for the Estimation of the Image-Derived Input Function in Dynamic [18F]-FDG PET Human Brain Studies

2009 ◽  
Vol 29 (11) ◽  
pp. 1825-1835 ◽  
Author(s):  
Paolo Zanotti-Fregonara ◽  
El Mostafa Fadaili ◽  
Renaud Maroy ◽  
Claude Comtat ◽  
Antoine Souloumiac ◽  
...  
Keyword(s):  
Blood Sample ◽  
Rate Constants ◽  
Fdg Pet ◽  
Input Function ◽  
Blood Samples ◽  
Arterial Blood ◽  
Positron Emission ◽  
Phantom Studies ◽  
The Individual ◽  
Individual Rate

The aim of this study was to compare eight methods for the estimation of the image-derived input function (IDIF) in [18F]-FDG positron emission tomography (PET) dynamic brain studies. The methods were tested on two digital phantoms and on four healthy volunteers. Image-derived input functions obtained with each method were compared with the reference input functions, that is, the activity in the carotid labels of the phantoms and arterial blood samples for the volunteers, in terms of visual inspection, areas under the curve, cerebral metabolic rates of glucose (CMRglc), and individual rate constants. Blood-sample-free methods provided less reliable results as compared with those obtained using the methods that require the use of blood samples. For some of the blood-sample-free methods, CMRglc estimations considerably improved when the IDIF was calibrated with a single blood sample. Only one of the methods tested in this study, and only in phantom studies, allowed a reliable calculation of the individual rate constants. For the estimation of CMRglc values using an IDIF in [18F]-FDG PET brain studies, a reliable absolute blood-sample-free procedure is not available yet.

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