Optimization of Spatial Resolution and Image Reconstruction Parameters for the Small-Animal MetisTM PET/CT System

The aim of this study was to investigate the optimization of spatial resolution and image reconstruction parameters related to image quality in an iterative reconstruction algorithm for the small-animal MetisTM PET/CT system. We used a homemade Derenzo phantom to evaluate the image quality by visual assessment, signal-to-noise ratio, contrast, coefficient of variation, and contrast-to-noise ratio of the 0.8 mm hot rods of 8 slices in the centre of the phantom PET images. A healthy mouse study was performed to analyze the influence of optimal reconstruction parameters and Gaussian post-filter FWHM. In the phantom study, the best image quality was obtained by placing the phantom at one end, keeping the central axis parallel to X-axis of the system, selecting iterations between 30 and 40, with a reconstruction voxel of 0.314 mm and a Gaussian post-filter FWHM of 1.57 mm. The optimization of spatial resolution can reach 0.6-mm. In the animal study, it was suitable to choose a voxel size of 0.472-mm, iterations between 30 and 40, and 2.36-mm Gaussian post-filter FWHM. Our results indicate that optimal imaging conditions and reconstruction parameters are necessary to obtain high-resolution images and quantitative accuracy, especially for the high-precision identification of tiny lesions.

Citrate dose for continuous hemofiltration: effect on calcium and magnesium balance, parathormone and vitamin D status, a randomized controlled trial

Background Regional citrate anticoagulation may cause a negative calcium balance, systemic hypocalcemia and parathormone (PTH) activation but randomzed studies are not available. Aim was to determine the effect of citrate dose on calcium (Ca) and magnesium (Mg) balance, PTH and Vitamin D. Methods Single center prospective randomized study. Patients, requiring continuous venovenous hemofiltration (CVVH) with citrate, randomized to low dose citrate (2.5 mmol/L) vs. high dose (4.5 mmol/L) for 24 h, targeting post-filter ionized calcium (pfiCa) of 0.325–0.4 mmol/L vs. 0.2–0.275 mmol/L, using the Prismaflex® algorithm with 100% postfilter calcium replacement. Extra physician-ordered Ca and Mg supplementation was performed aiming at systemic iCa > 1.0 mmol/L. Arterial blood, effluent and post-filter aliquots were taken for balance calculations (area under the curve), intact (i), oxidized (ox) and non-oxidized (nox) PTH, 25-hydroxy-Vitamin D (25D) and 1,25-dihydroxy-Vitamin D (1,25D). Results 35 patients were analyzed, 17 to high, 18 to low citrate. Mean 24-h Ca balance was - 9.72 mmol/d (standard error 1.70) in the high vs − 1.18 mmol/d (se 1.70)) (p = 0.002) in the low citrate group and 24-h Mg-balance was − 25.99 (se 2.10) mmol/d vs. -17.63 (se 2.10) mmol/d (p = 0.008) respectively. Physician-ordered Ca supplementation, higher in the high citrate group, resulted in a positive Ca-balance in both groups. iPTH, oxPTH or noxPTH were not different between groups. Over 24 h, median PTH decreased from 222 (25th–75th percentile 140–384) to 162 (111–265) pg/ml (p = 0.002); oxPTH from 192 (124–353) to 154 pg/ml (87–231), p = 0.002. NoxPTH did not change significantly. Mean 25 D (standard deviation), decreased from 36.5 (11.8) to 33.3 (11.2) nmol/l (p = 0.003), 1,25D rose from 40.9 pg/ml (30.7) to 43.2 (30.7) pg/ml (p = 0.046), without differences between groups. Conclusions A higher citrate dose caused a more negative CVVH Ca balance than a lower dose, due to a higher effluent Calcium loss. Physician-ordered Ca supplementation, targeting a systemic iCa > 1.0 mmol/L, higher in the high citrate group, resulted in a positive Ca-balance in both groups. iPTH and oxPTH declined, suggesting decreased oxidative stress, while noxPTH did not change. 25D decreased while 1,25-D rose. Mg balance was negative in both groups, more so in the high citrate group. Trial registration ClinicalTrials.gov: NCT02194569. Registered 18 July 2014.

Biocompatibility Parameters with Standard and Increased Dose of Citrate in Hemodialysis—A Randomized Trial

Background: The dose of citrate needed in regional citrate anticoagulation (RCA) to achieve optimal biocompatibility is unknown. We performed a randomized trial comparing two doses (ACTRN12613001340729). Methods: In 30 patients a single hemodialysis with either standard (2.7 mmol/L) or increased dose of citrate (4 mmol/L) was performed. C5a-desArg, myeloperoxidase (MPO), thrombin-antithrombin complex (TAT), and platelet factor 4 (PF4) were measured and the inner surface of the dialyzer fibers was evaluated with scanning electron microscopy (SEM). Results: A good separation of anticoagulation effect was achieved (post-filter ionized calcium 0.20 vs. 0.31 mmol/L, p < 0.05). There was no effect of citrate dose on any of the biocompatibility parameters; transient and parallel increase in PF4 after 30 min and parallel increase in TAT after 4 h were observed. There were no visually detected clotting problems within the circuit and no significant hypocalcemia in either group. SEM clotting score was excellent and comparable in both groups (p = 0.59). Conclusions: Given the excellent results in both groups, absence of between group differences and inability of the increased dose of citrate to completely blunt the small residual increase in PF4 and TAT, we conclude that the standard dose of citrate seems sufficient in RCA for chronic hemodialysis.

Effect of microaggregate filter passage on feline whole blood stored for 35 days

Objectives The aim of this study was to compare the characteristics of fresh and stored feline red blood cells (RBCs) after passage through an 18 μm microaggregate filter. Methods Nine cats were recruited for a single blood donation using an open collection system. A simulated transfusion using a syringe driver and microaggregate filter was performed over 2 h with half the blood on the day of donation and the other half after 35 days of storage. Differences in haematological parameters, haemolysis percentage and osmotic fragility (OF) were compared on the day of donation pre-filter passage (D0–) vs day of donation post-filter (D0+) or day 35 storage pre-filter (D35–) and post-filter (D35+). Blood was cultured at D0+ and D35+. Results There were no statistically significant differences in the D0– vs D0+ comparisons. There were statistically significant ( P <0.05) increases in haemolysis percentage, red cell distribution width (RDW) percentage and mean OF, and decreases in packed cell volume (PCV), RBC count, haemoglobin and haematocrit for D0– vs D35–. The same was found for D0– vs D35+ with the addition of a significant increase in mean cell haemoglobin (MCH). For D35– vs D35+ only MCH significantly increased. At day 35, 6/9 units had haemolysis percentages that exceeded 1%. This increased to 8/9 of stored units post-filter passage. All blood units cultured negative. Conclusions and relevance Fresh RBCs exhibited no in vitro evidence of injury following passage through an 18 μm microaggregate filter. Increased MCH was observed in the stored blood and may represent haemolysis induced by the filter. All other changes can be explained by storage lesion rather than filter passage. The findings highlight the importance of blood banking quality controls and the need for further research to assess the effects of transfusion technique, specifically filter passage, on storage lesion-affected feline blood.

Mathematical modelling of post-filter ionized calcium during citrate anticoagulated continuous renal replacement therapy

Background/Aims Post-filter ionized calcium (iCa) measured on a blood gas analyzer (BGA) during regional citrate anticoagulated continuous renal replacement therapy (CRRT) are needed to control the regime. This increases the workload and requires attention including interpretation of blood analyses. Two algorithms were developed to calculate the post-filter iCa instead. The first algorithm used measured systemic total calcium and the second used a selected set of values from an initial blood gas sample as input. Methods Calculated post-filter iCa values were compared to real blood gas analyses. 57 patients treated at the intensive care unit at Skåne University Hospital in Lund during 2010–2017 were included after applying inclusion and exclusion criteria. Clinical and machine parameters were collected from the electronic medical records. Non-quality checked data contained 1240 measurements and quality checked data contained 1034 measurements. Results The first algorithm using measured systemic total calcium resulted in slightly better precision and trueness with an average difference between the predicted and measured post-filter iCa concentration of 0.0185±0.0453 mmol/L for quality checked data, p<0.001. Neither algorithm could detect all instances requiring intervention. Conclusion The algorithms were able to estimate in range postfilter iCa values with great trueness and precision. However, they had some difficulties to estimate out-of-range postfilter iCa values. More work is needed to improve the algorithms especially in their citrate-modelling.

Diarrhea prevalence in a randomized, controlled prospective trial of point-of-use water filters in homes and schools in the Dominican Republic

Background Lack of sustainable access to clean drinking water continues to be an issue of paramount global importance, leading to millions of preventable deaths annually. Best practices for providing sustainable access to clean drinking water, however, remain unclear. Widespread installation of low-cost, in-home, point of use water filtration systems is a promising strategy. Methods We conducted a prospective, randomized, controlled trial whereby 16 villages were selected and randomly assigned to one of four treatment arms based on the installation location of Sawyer® PointONE™ filters (filter in both home and school; filter in home only; filter in school only; control group). Water samples and self-reported information on diarrhea were collected at multiple times throughout the study. Results Self-reported household prevalence of diarrhea decreased from 25.6 to 9.76% from installation to follow-up (at least 7 days, and up to 200 days post-filter installation). These declines were also observed in diarrhea with economic or educational consequences (diarrhea which led to medical treatment and/or missing school or work) with baseline prevalence of 9.64% declining to 1.57%. Decreases in diarrhea prevalence were observed across age groups. There was no evidence of a loss of efficacy of filters up to 200 days post-filter installation. Installation of filters in schools was not associated with decreases in diarrhea prevalence in school-aged children or family members. Unfiltered water samples both at schools and homes contained potential waterborne bacterial pathogens, dissolved heavy metals and metals associated with particulates. All dissolved metals were detected at levels below World Health Organization action guidelines. Conclusions This controlled trial provides strong evidence of the effectiveness of point-of-use, hollow fiber membrane filters at reducing diarrhea from bacterial sources up to 200 days post-installation when installed in homes. No statistically significant reduction in diarrhea was found when filters were installed in schools. Further research is needed in order to explore filter efficacy and utilization after 200 days post-installation. Trial registration ClinicalTrials.gov, NCT03972618. Registered 3 June 2019—retrospectively registered.