Random Field Ising Model Criticality in a Complex Binary Liquid System.

While Ising criticality in classical liquids has been firmly established both theoretically and experimentally, much less is known about criticality in liquids in which the growth of the correlation length is frustrated by finite-size effects. A theoretical approach for dealing with this issue is the random-field Ising model (RFIM). While experimental critical-exponent values have been reported for magnetic samples (here, we consider γ, ν and η), little experimental information is available for critical fluctuations in corresponding liquid systems. In this paper, we present a study on a binary liquid consisting of 3-methyl pyridine and heavy water in a very light-weight porous gel. We find that the experimental results are in agreement with the theoretical predictions from the RFIM.

Offline orbitofrontal cortex reactivation depends on recency of place-reward changes and coheres with hippocampal replay.

The orbitofrontal cortex, one of the key neocortical areas in valuation and emotion, is critical for cognitive flexibility but its role in the consolidation of recently acquired information remains unclear. Here, we demonstrate orbitofrontal offline replay in the context of a place-reward association task on a maze with varying goal locations. When switches in place-reward coupling were applied, replay was enhanced relative to sessions with stable contingencies. Moreover, replay strength was positively correlated with the subsequent overnight change in behavioral performance. Interrogating relationships between orbitofrontal and hippocampal activity, we found that orbitofrontal and hippocampal replay could occur independently but became coordinated during a type of cortical state with strong spiking activity. These findings reveal a structured form of offline orbitofrontal ensemble activity that is correlated with cognitive flexibility required to adapt to changing task contingencies, and becomes associated with hippocampal replay only during a specific state of high cortical excitability.

Effect of 24-h blood pressure dysregulations and reduced ocular perfusion pressure in open-angle glaucoma progression.

BACKGROUND: Low ocular perfusion pressure (OPP), which depends on the mean arterial pressure (MAP) and intraocular pressure (IOP), is associated with glaucoma. We studied 24-h MAP dysregulations and OPP in relation to the progression of glaucoma damage. METHODS: We retrospectively analyzed 155 normal-tension glaucoma (NTG) and 110 primary open-angle glaucoma (POAG) patients aged 18 years old followed at the University Hospital Leuven with repeated visual field tests ( n  = 7000 measures, including both eyes) who underwent 24-h ambulatory blood pressure monitoring. Twenty-four-hour MAP dysregulations were variability independent of the mean (VIM), and the five lowest dips in MAP readings over 24 h. OPP was the difference between 2/3 of the MAP and IOP. Glaucoma progression was the deterioration of the visual field, expressed as decibel (dB) changes in mean deviation analyzed by applying multivariable linear mixed regression models. RESULTS: The mean age was 68 years (53% were women). High 24-h VIMmap was associated with glaucoma progression in POAG ( P  < 0.001) independently of the 24-h MAP level. The estimated changes in mean deviation in relation to dip MAP measures ranged from -2.84 dB [95% confidence interval (CI) -4.12 to -1.57] to -2.16 dB (95% CI -3.46 to -0.85) in POAG. Reduced OPP along with high variability and dips in MAP resulted in worse mean deviation deterioration. CONCLUSION: The progression of glaucoma damage associates with repetitive and extreme dips in MAP caused by high variability in MAP throughout 24 h. This progression exacerbates if 24-h MAP dysregulations occur along with reduced OPP.

ANTI-ALCOHOL EDUCATION OF CHILDREN, YOUTH AND ADULTS AS A FACTOR IN THE FORMATION OF HEALTH-SAVING COMPETENCE THROUGH THE PRISM OF THE HISTORICAL EXPERIENCE OF UKRAINE.

OBJECTIVE: The aim: To analyze the leading trends in anti-alcohol education of children, youth and adults in Western Ukraine from the end of the 19th centry till the 1930s and to determine the possibilities of using this historical experience under modern conditions. PATIENTS AND METHODS: Materials and methods: A number of scientific methods were used in the research: chronological, historical, specific-search methods that provide selection, analysis of the source base, make it possible to determine general trends, directions, forms, achievements of anti-alcohol education of children, youth and adults in Western Ukraine from the end of the 19th century till the 1930s; extrapolation and actualization i.e. focus on creative understanding, adaptation and use of this historical experience under modern conditions, consideration of anti-alcohol education of children, youth and adults as a factor in the formation of health preservation and in general the Ukrainian gene pool under the modern challenges of the war, which Ukraine faced. CONCLUSION: Conclusions: Knowledge about a healthy lifestyle became the basis for people's health-preserving behavior, anti-alcohol education acted as a factor in the formation of the health-preserving competence of an individual, which included relevant knowledge, skills and behavior for creating and cultivating a health-preserving environment. This experience now deserves to be used creatively in the process of forming the health-saving competence of the individual throughout his life.

Weight-based vs body surface area-based fluid resuscitation predictions in pediatric burn patients.

Treatment for pediatric burns includes fluid resuscitation with formulas estimating fluid requirements based on weight and/or body surface area (BSA) with percent total body surface area burn (%TBSA burn). This study evaluates the risk of complications using weight-based resuscitation in children following burn injuries and compares fluid estimates with those that incorporate BSA. A retrospective review was conducted on 110 children admitted to an ABA-verified urban pediatric burn center over 12 years. Patients had ≥ 15% TBSA burn and were resuscitated with the weight-based Parkland formula. BSA-based Galveston and BSA-incorporated Cincinnati formula predictions were calculated. Complications were collected throughout hospital stay. Patients were classified into weight groups based on percentile. This study included 11 underweight, 60 normal weight, 18 overweight, and 21 obese children. Total fluid administered was higher as percentile increased; however, overweight children received more fluid than the obese (p = 0.023). The Galveston formula underpredicted fluid given over the first 24 h post-injury (p = 0.042); the Parkland and Cincinnati formula predictions did not significantly differ from fluids given. Further research is needed to determine the value of weight-based vs BSA-based or incorporated formulas in reducing risk of complications.

Progression of functional and structural glaucomatous damage in relation to diurnal and nocturnal dips in mean arterial pressure.

Background: Systemic hypoperfusion plays a pivotal role in the pathogenesis of primary open-angle glaucoma (POAG). Extreme dips in mean arterial pressure (MAP) due to high 24-h variability are associated with POAG, however, whether this is driven by diurnal or nocturnal dips remains undocumented. We aimed this study to investigate the association of POAG damage with variability and dips in the diurnal and nocturnal MAP. Methods: We conducted a retrospective longitudinal study that included 110 POAG patients who underwent 24-h ambulatory blood pressure monitoring. Our outcomes included (i) functional [visual field defects expressed as mean deviation (MD)] and (ii) structural (optic disc cupping obtained from cup-to-disc ratio) glaucoma damage. MAP variability independent of the mean (VIMmap) was computed for diurnal and nocturnal MAP. Dips were the five diurnal and three nocturnal lowest drops in MAP. We also calculated the night-to-day ratio. We applied mixed models to evaluate the progression of visual field defects and optic disc cupping in relation to diurnal and nocturnal MAP measures. Results: The mean age was 64.0 y (53% women). The median follow-up was 9 years. In adjusted mixed models, functional progression of glaucoma damage was associated with VIMmap (-2.57 dB change in MD per every 3 mmHg increase in VIMmap; P < 0.001) and diurnal MAP dips (changes in the MD ranged from -2.56 to -3.19 dB; P < 0.001). Every 5 mmHg decrease in the nocturnal MAP level was associated with -1.14 dB changes in MD [95% confidence interval (CI), -1.90 to -0.40] and 0.01 larger optic disc cupping (95% CI, 0.01-0.02). Lower night-to-day ratio was also related to both outcomes (P ≤ 0.012). Functional glaucoma damage worsened if nocturnal hypotension was combined with high variability or extreme dips in the diurnal MAP (P ≤ 0.022). Conclusion: Progression of glaucoma damage in POAG associates with high variability and extreme dips in the diurnal MAP. Structural glaucoma damage seems more vulnerable to nocturnal hypotension. Ambulatory blood pressure monitoring allows the assessment of sporadic diurnal and persistent nocturnal hypotension episodes. These phenotypes might offer an opportunity to improve the risk-stratification of open-angle glaucoma (OAG).

Determination of the Optimal Level of Dietary Zinc for Newly Weaned Pigs: A Dose-Response Study.

One hundred and eighty individually housed piglets with an initial body weight of 7.63 ± 0.98 kg (at 28 days of age) were fed a diet containing either 153, 493, 1022, 1601, 2052 or 2407 mg zinc/kg (added Zn as zinc oxide; ZnO) from day 0-21 post weaning to determine the optimal level of Zn for weaned piglets. Body weight, feed intake and faecal scores were recorded, and blood and faecal samples were collected. Dietary Zn content quadratically affected both feed intake and gain in the first two weeks, with an approximately 1400 mg Zn/kg diet and a Zn intake of 400 mg/day as the optimal levels. The relative risk of diarrhoea increased up to 60% at day 7 and 14 if serum Zn status dropped below the weaning level (767 µg/L), and maintain the weaning serum Zn status required approximately 1100 mg Zn/kg (166 mg Zn/day) during week 1. Blood markers of intestinal integrity (D-lactate and diamine oxidase) were unaffected by dietary Zn, and dietary Zn levels of 1022 and 1601 mg/kg did not affect the faecal numbers of total bacteria, Lactobacilli and E. Coli bacteria compared to 153 mg Zn/kg. These results indicate that the requirement for Zn in newly weaned piglets may be substantially higher than currently assumed.

Open-Angle Glaucomatous Optic Neuropathy Is Related to Dips Rather Than Increases in the Mean Arterial Pressure Over 24-H.

BACKGROUND: Mean arterial pressure (MAP) drives ocular perfusion. Excessive 24-h MAP variability relates to glaucoma, however, whether this is due to dips or increases in the blood pressure (BP) is undocumented. We investigated the association of open-angle glaucoma (OAG) in relation to the 5 largest MAP dips/increases over 24-h, henceforth called dips/blips. METHODS: In the Maracaibo Aging Study (MAS), 93 participants aged ≥40 y (women, 87.1%; mean age, 61.9 y) underwent baseline ophthalmological and 24-h ambulatory BP monitoring assessments. OAG was the presence of optic nerve damage and visual field defects. Statistical methods included logistic regression and the generalized R2 statistic. For replication, 48 OAG cases at the Leuven Glaucoma Clinic were matched with 48 controls recruited from Flemish population. RESULTS: In the MAS, 26 participants had OAG. OAG compared to non-OAG participants experienced longer and deeper dips (116.5 vs. 102.7 minutes; to 60.3 vs. 66.6 mm Hg; -21.0 vs. -18.0 mm Hg absolute or 0.79 vs. 0.81 relative dip compared to the preceding reading). The adjusted odds ratios associated with dip measures ranged from 2.25 (95% confidence interval [CI], 1.31-4.85; P = 0.009) to 3.39 (95% CI, 1.36-8.46; P = 0.008). On top of covariables and 24-MAP level/variability, the dip measures increased the model performance (P ≤ 0.025). Blips did not associate with OAG. The case-control study replicated the MAS observations. CONCLUSIONS: Dips rather than increases in the 24-h MAP level were associated with increased risk for OAG. An ophthalmological examination combined with 24-h BP monitoring might be precautious steps required in normotensive and hypertensive patients at risk of OAG.

Some Insect Species Are Good-Quality Protein Sources for Children and Adults: Digestible Indispensable Amino Acid Score (DIAAS) Determined in Growing Pigs.

BACKGROUND: Insect species are suitable for farming as "mini livestock" for human and animal consumption. It is important to assess the protein quality of relevant species to understand the potential of these novel protein sources in future sustainable food systems. OBJECTIVES: We aimed to determine the protein quality of 5 insect species-lesser mealworm (LMW), yellow mealworm, house cricket (HC), banded cricket (BC), and black soldier fly-using the digestible indispensable amino acid score (DIAAS) in a pig model. METHODS: Five diets were formulated to contain 10% insect crude protein (CP). A nitrogen (N)-free diet was included to estimate endogenous losses. In a 6 × 6 Latin square design, 6 ileal cannulated crossbred [Duroc × (Danish Landrace × Yorkshire)] male pigs with an initial body weight of 35 ± 2 kg were fed the 6 diets. Each diet was fed for 1 wk over 6 wk. Ileal digesta were collected for 8 h on days 5 and 7 each week. Analyzed CP, amino acid (AA) contents, and calculated values of standardized ileal digestibility for CP and AAs were used to assess the DIAAS of each insect. RESULTS: The DIAAS for young children aged 6 mo-3 y and for older children, adolescents, and adults identified sulfur AAs (cysteine + methionine) as the first limiting AA in all 4 species of cricket and mealworm. For young children, both cricket species had DIAASs > 75 and for older children, adolescents, and adults both cricket species and LMW had DIAASs > 75. CONCLUSIONS: Both cricket species (HC and BC) are classified as good-quality protein sources for young children aged 6 mo-3 y and for older children, adolescents, and adults. One mealworm species, LMW, is a good-quality protein source for older children, adolescents, and adults.

Some Insect Species Are Good-Quality Protein Sources for Children and Adults: Digestible Indispensable Amino Acid Score (DIAAS) Determined in Growing Pigs.

BACKGROUND: Insect species are suitable for farming as "mini livestock" for human and animal consumption. It is important to assess the protein quality of relevant species to understand the potential of these novel protein sources in future sustainable food systems. OBJECTIVES: We aimed to determine the protein quality of 5 insect species-lesser mealworm (LMW), yellow mealworm, house cricket (HC), banded cricket (BC), and black soldier fly-using the digestible indispensable amino acid score (DIAAS) in a pig model. METHODS: Five diets were formulated to contain 10% insect crude protein (CP). A nitrogen (N)-free diet was included to estimate endogenous losses. In a 6 × 6 Latin square design, 6 ileal cannulated crossbred [Duroc × (Danish Landrace × Yorkshire)] male pigs with an initial body weight of 35 ± 2 kg were fed the 6 diets. Each diet was fed for 1 wk over 6 wk. Ileal digesta were collected for 8 h on days 5 and 7 each week. Analyzed CP, amino acid (AA) contents, and calculated values of standardized ileal digestibility for CP and AAs were used to assess the DIAAS of each insect. RESULTS: The DIAAS for young children aged 6 mo-3 y and for older children, adolescents, and adults identified sulfur AAs (cysteine + methionine) as the first limiting AA in all 4 species of cricket and mealworm. For young children, both cricket species had DIAASs > 75 and for older children, adolescents, and adults both cricket species and LMW had DIAASs > 75. CONCLUSIONS: Both cricket species (HC and BC) are classified as good-quality protein sources for young children aged 6 mo-3 y and for older children, adolescents, and adults. One mealworm species, LMW, is a good-quality protein source for older children, adolescents, and adults.

Peanut allergy in Italy: A unique Italian perspective.

Background: Peanut allergy has not been well characterized in Italy. Objective: Our aim was to better define the clinical features of peanut allergy in Italy and to detect the peanut proteins involved in allergic reactions. Methods: A total of 22 centers participated in a prospective survey of peanut allergy over a 6-month period. Clinical histories were confirmed by in vivo and/or in vitro diagnostic means in all cases. Potential risk factors for peanut allergy occurrence were considered. Levels of IgE to Arachis hypogea (Ara h) 1, 2, 3, 6, 8, and 9 and profilin were measured. Results: A total of 395 patients (aged 2-80 years) were enrolled. Of the participants, 35% reported local reactions, 38.2% reported systemic reactions, and 26.6% experienced anaphylaxis. The sensitization profile was dominated by Ara h 9 (77% of patients were sensitized to it), whereas 35% were sensitized to pathogenesis-related protein 10 (PR-10) and 26% were sensitized to seed storage proteins (SSPs). Sensitization to 2S albumins (Ara h 2 and Ara h 6) or lipid transfer protein (LTP) was associated with the occurrence of more severe symptoms, whereas profilin and PR-10 sensitization were associated with milder symptoms. Cosensitization to profilin reduced the risk of severe reactions in both Ara h 2- and LTP-sensitized patients. SSP sensitization prevailed in younger patients whereas LTP prevailed in older patients (P < .01). SSP sensitization occurred mainly in northern Italy, whereas LTP sensitization prevailed in Italy's center and south. Atopic dermatitis, frequency of peanut ingestion, peanut consumption by other family members, or use of peanut butter did not seem to be risk factors for peanut allergy onset. Conclusions: In Italy, peanut allergy is rare and dominated by LTP in the country's center and south and by SSP in the north. These 2 sensitizations seem mutually exclusive. The picture differs from that in Anglo-Saxon countries.

Changes in the membrane lipid composition of a Sulfurimonas species depend on the electron acceptor used for sulfur oxidation.

Sulfurimonas species are among the most abundant sulfur-oxidizing bacteria in the marine environment. They are capable of using different electron acceptors, this metabolic flexibility is favorable for their niche adaptation in redoxclines. When oxygen is depleted, most Sulfurimonas spp. (e.g., Sulfurimonas gotlandica) use nitrate ([Formula: see text]) as an electron acceptor to oxidize sulfur, including sulfide (HS-), S0 and thiosulfate, for energy production. Candidatus Sulfurimonas marisnigri SoZ1 and Candidatus Sulfurimonas baltica GD2, recently isolated from the redoxclines of the Black Sea and Baltic Sea respectively, have been shown to use manganese dioxide (MnO2) rather than [Formula: see text] for sulfur oxidation. The use of different electron acceptors is also dependent on differences in the electron transport chains embedded in the cellular membrane, therefore changes in the membrane, including its lipid composition, are expected but are so far unexplored. Here, we used untargeted lipidomic analysis to reveal changes in the composition of the lipidomes of three representative Sulfurimonas species grown using either [Formula: see text] and MnO2. We found that all Sulfurimonas spp. produce a series of novel phosphatidyldiazoalkyl-diacylglycerol lipids. Ca. Sulfurimonas baltica GD2 adapts its membrane lipid composition depending on the electron acceptors it utilizes for growth and survival. When carrying out MnO2-dependent sulfur oxidation, the novel phosphatidyldiazoalkyl-diacylglycerol headgroup comprises shorter alkyl moieties than when sulfur oxidation is [Formula: see text]-dependent. This is the first report of membrane lipid adaptation when an organism is grown with different electron acceptors. We suggest novel diazoalkyl lipids have the potential to be used as a biomarker for different conditions in redox-stratified systems.

SANITARY AND HYGIENIC EDUCATION OF CHILDREN AND ADULTS UNDER THE CONDITIONS OF THE COVID-19 PANDEMIC IN MEASUREMENT OF THE ACHIEVEMENTS OF PUBLIC MEDICINE OF GALICIA (END OF THE XIX - 30S OF THE XX CENTURY).

OBJECTIVE: The aim: To analyze the leading trends in sanitary and hygienic education of children and adults in Galicia during the late XIX - the 30s of the XX century and define opportunities to use this historical experience in the current context of the spread of COVID-19 virus in Ukraine. PATIENTS AND METHODS: Materials and methods: Chronological, historical, specific search, content-analysis- provide selection and analysis of the source base, allow to determine general trends, directions of development, achievements and gaps of sanitary and hygienic education of children and adults in Galicia in the late XIX - 30sof the XX century; extrapolation and actualization - focus on creative thinking, adaptation and use of this historical experience in today's conditions. CONCLUSION: Conclusions: Under the current conditions of the COVID-19 spread, analysis of this retro experience projects to develop a scientific concept of health education, which would outline theoretical approaches to studying this problem, creating a comprehensive state program aimed at preventing infectious diseases, restoration of gene elaboration of clear recommendations on observance of sanitary and hygienic norms and conditions established by quarantine zones, carrying out anti-epidemic measures at educational institutions and among the adult population, informing about prevention and peculiarities of the COVID-19 disease spread, etc.

Amino Acid Absorption Profiles in Growing Pigs Fed Different Protein Sources.

The aim of the present study was to determine postprandial amino acid (AA) appearance in the blood of growing pigs as influenced by protein source. Seven growing pigs (average body weight 18 kg), in a 7 × 5 Youden square design, were fitted with a jugular vein catheter and fed seven diets containing wheat, soybean meal, enzyme-treated soybean meal, hydrothermally-treated rapeseed meal, casein, hydrolyzed casein, and a crystalline AA blend with the same AA profile as casein. The latter was not eaten by the pigs, therefore being excluded. Blood samples were collected at -30, 30, 60, 90, 120, 180, and 360 min after a meal and analyzed for free AA. Overall, plasma AA concentrations were highest 60 min after feeding. There were no differences in plasma AA concentration between casein and hydrolyzed casein, but soybean meal resulted in lower AA plasma concentrations compared with enzyme-treated soybean meal at 60 and 120 min after feeding. There were no differences between hydrothermally-treated rapeseed meal and soybean meal. In conclusion, the ingredients could not clearly be categorized as being slow or fast protein with regard to protein digestion and absorption of AA, but soybean meal resulted in a prolonged appearance of plasma AA compared to casein and hydrolyzed casein.

Candidatus Sulfurimonas marisnigri sp. nov. and Candidatus Sulfurimonas baltica sp. nov., thiotrophic manganese oxide reducing chemolithoautotrophs of the class Campylobacteria isolated from the pelagic redoxclines of the Black Sea and the Baltic Sea.

Species of the genus Sulfurimonas are reported and isolated from terrestrial habitats and marine sediments and water columns with steep redox gradients. Here we report on the isolation of strains SoZ1 and GD2 from the pelagic redoxcline of the Black Sea and the Baltic Sea, respectively. Both strains are gram-stain-negative and appear as short and slightly curved motile rods. The autecological preferences for growth of strain SoZ1 were 0-25°C (optimum 20°C), pH 6.5-9.0 (optimum pH 7.5-8.0) and salinity 10-40gL-1 (optimum 25gL-1). Preferences for growth of strain GD2 were 0-20°C (optimum 15°C), pH 7.0-8.0 (optimum pH 7.0-7.5) and salinity 5-40gL-1 (optimum 21gL-1). Strain SoZ1 grew chemolithoautotrophically, while strain GD2 also showed heterotrophic growth with short chained fatty acids as carbon source. Both species utilized hydrogen (H2), sulfide (H2S here taken as the sum of H2S, HS- and S2-), elemental sulfur (S0) and thiosulfate (S2O32-) as electron donors and nitrate (NO3-), oxygen (O2) and particulate manganese oxide (MnO2) as electron acceptors. Based on 16S rRNA gene sequence similarity, both strains cluster within the genus Sulfurimonas with Sulfurimonas gotlandica GD1T as the closest cultured relative species with a sequence similarity of 96.74% and 96.41% for strain SoZ1 and strain GD2, respectively. Strains SoZ1 and GD2 share a ribosomal 16S sequence similarity of 99.27% and were demarcated based on average nucleotide identity and average amino acid identity of the whole genome sequence. These calculations have been applied to the whole genus. We propose the names Candidatus Sulfurimonas marisnigri sp. nov. and Candidatus Sulfurimonas baltica sp. nov. for the thiotrophic manganese reducing culture isolates from the Black Sea and Baltic Sea, respectively.

Performance evaluation of fifth-generation ultra-high-resolution SPECT system with two stationary detectors and multi-pinhole imaging.

BACKGROUND: Small-animal single-photon emission computed tomography (SPECT) systems with multi-pinhole collimation and large stationary detectors have advantages compared to systems with moving small detectors. These systems benefit from less labour-intensive maintenance and quality control as fewer prone parts are moving, higher accuracy for focused scans and maintaining high resolution with increased sensitivity due to focused pinholes on the field of view. This study aims to investigate the performance of a novel ultra-high-resolution scanner with two-detector configuration (U-SPECT5-E) and to compare its image quality to a conventional micro-SPECT system with three stationary detectors (U-SPECT+). METHODS: The new U-SPECT5-E with two stationary detectors was used for acquiring data with 99mTc-filled point source, hot-rod and uniformity phantoms to analyse sensitivity, spatial resolution, uniformity and contrast-to-noise ratio (CNR). Three dedicated multi-pinhole mouse collimators with 75 pinholes each and 0.25-, 0.60- and 1.00-mm pinholes for extra ultra-high resolution (XUHR-M), general-purpose (GP-M) and ultra-high sensitivity (UHS-M) imaging were examined. For CNR analysis, four different activity ranges representing low- and high-count settings were investigated for all three collimators. The experiments for the performance assessment were repeated with the same GP-M collimator in the three-detector U-SPECT+ for comparison. RESULTS: Peak sensitivity was 237 cps/MBq (XUHR-M), 847 cps/MBq (GP-M), 2054 cps/MBq (UHS-M) for U-SPECT5-E and 1710 cps/MBq (GP-M) for U-SPECT+. In the visually analysed sections of the reconstructed mini Derenzo phantoms, rods as small as 0.35 mm (XUHR-M), 0.50 mm (GP-M) for the two-detector as well as the three-detector SPECT and 0.75 mm (UHS-M) were resolved. Uniformity for maximum resolution recorded 40.7% (XUHR-M), 29.1% (GP-M, U-SPECT5-E), 16.3% (GP-M, U-SPECT+) and 23.0% (UHS-M), respectively. UHS-M reached highest CNR values for low-count images; for rods smaller than 0.45 mm, acceptable CNR was only achieved by XUHR-M. GP-M was superior for imaging rods sized from 0.60 to 1.50 mm for intermediate activity concentrations. U-SPECT5-E and U-SPECT+ both provided comparable CNR. CONCLUSIONS: While uniformity and sensitivity are negatively affected by the absence of a third detector, the investigated U-SPECT5-E system with two stationary detectors delivers excellent spatial resolution and CNR comparable to the performance of an established three-detector-setup.

Capabilities of multi-pinhole SPECT with two stationary detectors for in vivo rat imaging.

We aimed to investigate the image quality of the U-SPECT5/CT E-Class a micro single-photon emission computed tomography (SPECT) system with two large stationary detectors for visualization of rat hearts and bones using clinically available 99mTc-labelled tracers. Sensitivity, spatial resolution, uniformity and contrast-to-noise ratio (CNR) of the small-animal SPECT scanner were investigated in phantom studies using an ultra-high-resolution rat and mouse multi-pinhole collimator (UHR-RM). Point source, hot-rod, and uniform phantoms with 99mTc-solution were scanned for high-count performance assessment and count levels equal to animal scans, respectively. Reconstruction was performed using the similarity-regulated ordered-subsets expectation maximization (SROSEM) algorithm with Gaussian smoothing. Rats were injected with ~ 100 MBq [99mTc]Tc-MIBI or ~ 150 MBq [99mTc]Tc-HMDP and received multi-frame micro-SPECT imaging after tracer distribution. Animal scans were reconstructed for three different acquisition times and post-processed with different sized Gaussian filters. Following reconstruction, CNR was calculated and image quality evaluated by three independent readers on a five-point scale from 1 = "very poor" to 5 = "very good". Point source sensitivity was 567 cps/MBq and radioactive rods as small as 1.2 mm were resolved with the UHR-RM collimator. Collimator-dependent uniformity was 55.5%. Phantom CNR improved with increasing rod size, filter size and activity concentration. Left ventricle and bone structures were successfully visualized in rat experiments. Image quality was strongly affected by the extent of post-filtering, whereas scan time did not have substantial influence on visual assessment. Good image quality was achieved for resolution range greater than 1.8 mm in bone and 2.8 mm in heart. The recently introduced small animal SPECT system with two stationary detectors and UHR-RM collimator is capable to provide excellent image quality in heart and bone scans in a rat using standardized reconstruction parameters and appropriate post-filtering. However, there are still challenges in achieving maximum system resolution in the sub-millimeter range with in vivo settings under limited injection dose and acquisition time.