Deep learning denoising reconstruction enables faster T2-weighted FLAIR sequence acquisition with satisfactory image quality.

INTRODUCTION: Deep learning reconstruction (DLR) technologies are the latest methods attempting to solve the enduring problem of reducing MRI acquisition times without compromising image quality. The clinical utility of this reconstruction technique is yet to be fully established. This study aims to assess whether a commercially available DLR technique applied to 2D T2-weighted FLAIR brain images allows a reduction in scan time, without compromising image quality and thus diagnostic accuracy. METHODS: 47 participants (24 male, mean age 55.9 ± 18.7 SD years, range 20-89 years) underwent routine, clinically indicated brain MRI studies in March 2022, that included a standard-of-care (SOC) T2-weighted FLAIR sequence, and an accelerated acquisition that was reconstructed using the DLR denoising product. Overall image quality, lesion conspicuity, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and artefacts for each sequence, and preferred sequence on direct comparison, were subjectively assessed by two readers. RESULTS: There was a strong preference for SOC FLAIR sequence for overall image quality (P = 0.01) and head-to-head comparison (P < 0.001). No difference was observed for lesion conspicuity (P = 0.49), perceived SNR (P = 1.0), and perceived CNR (P = 0.84). There was no difference in motion (P = 0.57) nor Gibbs ringing (P = 0.86) artefacts. Phase ghosting (P = 0.038) and pseudolesions were significantly more frequent (P < 0.001) on DLR images. CONCLUSION: DLR algorithm allowed faster FLAIR acquisition times with comparable image quality and lesion conspicuity. However, an increased incidence and severity of phase ghosting artefact and presence of pseudolesions using this technique may result in a reduction in reading speed, efficiency, and diagnostic confidence.

Common Era sea-level budgets along the U.S. Atlantic coast.

Sea-level budgets account for the contributions of processes driving sea-level change, but are predominantly focused on global-mean sea level and limited to the 20th and 21st centuries. Here we estimate site-specific sea-level budgets along the U.S. Atlantic coast during the Common Era (0-2000 CE) by separating relative sea-level (RSL) records into process-related signals on different spatial scales. Regional-scale, temporally linear processes driven by glacial isostatic adjustment dominate RSL change and exhibit a spatial gradient, with fastest rates of rise in southern New Jersey (1.6 ± 0.02 mm yr-1). Regional and local, temporally non-linear processes, such as ocean/atmosphere dynamics and groundwater withdrawal, contributed between -0.3 and 0.4 mm yr-1 over centennial timescales. The most significant change in the budgets is the increasing influence of the common global signal due to ice melt and thermal expansion since 1800 CE, which became a dominant contributor to RSL with a 20th century rate of 1.3 ± 0.1 mm yr-1.

Publisher Correction: Cosmogenic exposure dating reveals limited long-term variability in erosion of a rocky coastline.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Cosmogenic exposure dating reveals limited long-term variability in erosion of a rocky coastline.

Predicted sea-level rise and increased storminess are anticipated to lead to increases in coastal erosion. However, assessing if and how rocky coasts will respond to changes in marine conditions is difficult due to current limitations of monitoring and modelling. Here, we measured cosmogenic 10Be concentrations across a sandstone shore platform in North Yorkshire, UK, to model the changes in coastal erosion within the last 7 kyr and for the first time quantify the relative long-term erosive contribution of landward cliff retreat, and down-wearing and stripping of rock from the shore platform. The results suggest that the cliff has been retreating at a steady rate of 4.5 ± 0.63 cm yr-1, whilst maintaining a similar profile form. Our results imply a lack of a direct relationship between relative sea level over centennial to millennial timescales and the erosion response of the coast, highlighting a need to more fully characterise the spatial variability in, and controls on, rocky coast erosion under changing conditions.

Organic pollutants, heavy metals and toxicity in oil spill impacted salt marsh sediment cores, Staten Island, New York City, USA.

Sediment cores from Staten Island's salt marsh contain multiple historical oil spill events that impact ecological health. Microtox solid phase bioassay indicated moderate to high toxicity. Multiple spikes of TPH (6524 to 9586 mg/kg) and Σ16 PAH (15.5 to 18.9 mg/kg) were co-incident with known oil spills. A high TPH background of 400-700 mg/kg was attributed to diffuse sources. Depth-profiled metals Cu (1243 mg/kg), Zn (1814 mg/kg), Pb (1140 mg/kg), Ni (109 mg/kg), Hg (7 mg/kg), Cd 15 (mg/kg) exceeded sediment quality guidelines confirming adverse biological effects. Changes in Pb206/207 suggested three metal contaminant sources and diatom assemblages responded to two contamination events. Organic and metal contamination in Saw Mill Creek Marsh may harm sensitive biota, we recommend caution in the management of the 20-50 cm sediment interval because disturbance could lead to remobilisation of pre-existing legacy contamination into the waterway.

Goals of care conversations and documentation in patients triggering medical emergency team calls.

BACKGROUND: It is widely accepted that early discussions about goals of care (GOC) should occur during a hospital admission. Whilst rapid response systems such as Medical Emergency Team (MET) calls were designed to identify patients at risk of deterioration early enough in their illness to intervene, it is becoming apparent that these teams frequently diagnose the dying patient. AIMS: To determine how frequently Launceston General Hospital MET doctors are involved in discussions surrounding GOC. METHODS: A retrospective audit of all MET calls and Code Blues at the Launceston General Hospital over an 18 month period was performed. RESULTS: 50% of MET calls occurred in patients with no valid GOC form completed prior. At 3% of events, the GOC form was completed for the first time, and at 3% it was modified. At a further 3% the notes implied there had been a modification to the GOC but the form had not been completed. CONCLUSIONS: This audit confirms that documentation surrounding GOC is inadequate, and that at 9% of MET calls, MET doctors are involved in discussions surrounding treatment limitations. This suggests that further education and training is required for doctors working in inpatient care, including those who staff the MET.

Rapid response team trigger modifications: are we using them safely?

BACKGROUND: Rapid response teams (RRT) were first proposed as a means of reducing inpatient morbidity and mortality. Modifying RRT activation triggers poses a potential risk for delayed recognition of a deteriorating patient. Trigger modifications have not been validated for safety. AIMS: To determine if RRT trigger modifications are associated with: increased frequency of recurrent RRT activation; increased length of stay (LOS); increased intensive care admission; and increased in-hospital mortality. METHODS: A retrospective audit of all RRT activations occurring at the Launceston General Hospital (LGH) over an 18-month period was performed. RESULTS: Rate of recurrent RRT activations did not decrease with the use of trigger modifications around the time of RRT activation, and for patients with two modifications, the frequency increased (1.98 vs 1.32, P = 0.007). LGH LOS increased for patients with any trigger modifications compared to those with none (11 vs 9, P = 0.0002), and for patients with two modifications (11.5 vs 9, P = 0.010). Total hospital LOS increased for patients with any modifications compared to patients with none (12 vs 10, P = 0.002). There was no significant association between trigger modifications and frequency of intensive care unit admission. The relative risk of in-hospital death increased with increasing numbers of trigger modifications (relative risk 1.38-4.89). CONCLUSIONS: Trigger modifications are associated with increased hospital LOS and increased rate of in-hospital death and do not reduce the number of recurrent events. For patients in whom escalation of care is not appropriate, the presence of multiple trigger modifications at the time of an RRT activation may be a useful trigger for conversations around goals of care.

Comparison of pre-filter and post-filter ionised calcium monitoring in continuous veno-venous hemodiafiltration (CVVHD-F) with citrate anti-coagulation.

BACKGROUND: It is widespread practice during citrate anticoagulated renal replacement therapy to monitor circuit ionised calcium (iCa2+) to evaluate the effectiveness of anticoagulation. Whether the optimal site to sample the blood path is before or after the haemofilter is a common question. METHODS: Using a prospectively collected observational dataset from intensive care patients receiving pre-dilution continuous veno-venous haemodiafiltration (CVVHD-F) with integrated citrate anticoagulation we compared paired samples of pre and post filter iCa2+ where the target range was 0.3-0.5 mmol.L-1 as well as concurrently collected arterial iCa2+. Two nested mixed methods linear models were fitted to the data describing post vs pre filter iCa2+, and the relationship of pre, post and arterial samples. SETTING: An 11 bed general intensive care unit. PARTICIPANTS: 450 grouped samples from 152 time periods in seven patients on CRRT with citrate anticoagulation. RESULTS: The relationship of post to pre-filter iCa2+ was not 1:1 with post = 0.082 + 0.751 x pre-filter iCa2+ (95% CI intercept: 0.015-0.152, slope 0.558-0.942). Variation was greatest between patients rather than between circuits within the same patient or citrate dose. Compared to arterial iCa2+ there was no significant difference between pre and post-filter sampling sites (F-value 0.047, p = 0.827). CONCLUSION: These results demonstrate that there is minimal difference between pre and post filter samples for iCa2+ monitoring of circuit anticoagulation in citrate patients relative to the arterial iCa2+ in CVVHD-F however compared to pre-filter sampling, post filter sampling has a flatter response and greater variation.

Non anti-coagulant factors associated with filter life in continuous renal replacement therapy (CRRT): a systematic review and meta-analysis.

BACKGROUND: Optimising filter life and performance efficiency in continuous renal replacement therapy has been a focus of considerable recent research. Larger high quality studies have predominantly focussed on optimal anticoagulation however CRRT is complex and filter life is also affected by vascular access, circuit and management factors. We performed a systematic search of the literature to identify and quantify the effect of vascular access, circuit and patient factors that affect filter life and presented the results as a meta-analysis. METHODS: A systematic review and meta-analysis was performed by searching Pubmed (MEDLINE) and Ovid EMBASE libraries from inception to 29th February 2016 for all studies with a comparator or independent variable relating to CRRT circuits and reporting filter life. Included studies documented filter life in hours with a comparator other than anti-coagulation intervention. All studies comparing anticoagulation interventions were searched for regression or hazard models pertaining to other sources of variation in filter life. RESULTS: Eight hundred nineteen abstracts were identified of which 364 were selected for full text analysis. 24 presented data on patient modifiers of circuit life, 14 on vascular access modifiers and 34 on circuit related factors. Risk of bias was high and findings are hypothesis generating. Ranking of vascular access site by filter longevity favours: tunnelled semi-permanent catheters, femoral, internal jugular and subclavian last. There is inconsistency in the difference reported between femoral and jugular catheters. Amongst published literature, modality of CRRT consistently favoured continuous veno-venous haemodiafiltration (CVVHD-F) with an associated 44% lower failure rate compared to CVVH. There was a trend favouring higher blood flow rates. There is insufficient data to determine advantages of haemofilter membranes. Patient factors associated with a statistically significant worsening of filter life included mechanical ventilation, elevated SOFA or LOD score, elevations in ionized calcium, elevated platelet count, red cell transfusion, platelet factor 4 (PF-4) antibodies, and elevated fibrinogen. Majority of studies are observational or report circuit factors in sub-analysis. Risk of bias is high and findings require targeted investigations to confirm. CONCLUSION: The interaction of patient, pathology, anticoagulation, vascular access, circuit and staff factors contribute to CRRT filter life. There remains an ambiguity from published data as to which site and side should be the first choice for vascular access placement and what interaction this has with patient factors and timing. Early consideration of tunnelled semi-permanent access may provide optimal filter life if longer periods of CRRT are anticipated. There remains an absence of robust evidence outside of anti-coagulation strategies despite over 20 years of therapy delivery however trends favour CVVHD-F over CVVH.

Vascular access site influences circuit life in continuous renal replacement therapy.

OBJECTIVE: To determine the influence of vascular access site on continuous renal replacement therapy (CRRT) filter survival. DESIGN, SETTING AND PATIENTS: Retrospective study of the records of patients who received CRRT in The Alfred intensive care unit from June 2011 to May 2012. MAIN OUTCOME MEASURE: Filter run time. METHODS: We matched filter run time to site and type of vascular access. Mean run times were compared using a linear mixed-effects model between: temporary femoral, internal jugular (IJ) and subclavian catheters, tunnelled semipermanent IJ catheters, and extracorporeal membrane oxygenation (ECMO) circuit access. The Markov chain Monte Carlo method was used to construct 95% confidence intervals, and the Wilcoxon rank sum test was used for post hoc testing of significance. RESULTS: Filter run-time data were available for 131 patients (191 occasions of vascular access) with a total of 870 individual filters analysed. Mean run times were subclavian, 14.4 h; IJ, 17.1 h; femoral, 20.2 h; tunnelled IJ, 25.2 h; and ECMO, 29.0 h. Differences were significant for all combinations except between subclavian and IJ, and between tunnelled access and ECMO. Sites in order of best performing to worst-performing were ECMO circuit, tunnelled IJ, femoral vein, direct IJ vein, and subclavian vein. CONCLUSION: Vascular access for CRRT plays a significant role in determining filter life. Our study suggests that for temporary dialysis catheters the femoral site should be favoured in ICU patients, and if CRRT is likely to continue for an extended period, a tunnelled IJ line should be considered.

Randomised trial of software algorithm driven regional citrate anticoagulation versus heparin in continuous renal replacement therapy: the Filter Life in Renal Replacement Therapy pilot trial.

OBJECTIVE: The effectiveness of continuous renal replacement therapy (CRRT) increases when unplanned circuit failure is prevented. Adequate anticoagulation is an important component. Although heparin is the predominating anticoagulant, calcium chelation with citrate is an alternative, but systemic calcium monitoring and supplementation increase the complexity of CRRT. We assessed efficacy and safety of citrate delivery via integrated software algorithms against an established regional heparin protocol. DESIGN: Prospective computer randomisation allocated eligible patients to regional citrate or heparin between April and December 2012. Citrate fluids were Prismocitrate 18 mmol/L predilution and Prism0cal B22 dialysate. Hemosol B0 was the default fluid for heparin. The primary outcome was filter running time. Electively terminated circuits were censored. Intention-totreat (ITT) and per-protocol analyses were performed. Filter survival was compared by log-rank tests and hazard ratios were explored with a mixed-effects Cox model. RESULTS: 221 filters were analysed from 30 patients (of whom 19 were randomly allocated to citrate filters and 11 to heparin filters). Patients randomly allocated to citrate were older, sicker, with a higher male:female ratio, but of similar weight. Mortality was 37% in the citrate arm and 27% in the heparin arm. All deaths were attributed to underlying disease. Significant crossover occurred from the citrate arm to use of heparin. Median filter survival, by ITT, was not significantly different (citrate, 34 hours; heparin, 30.7 hours; P=0.58). Per-protocol survival favoured citrate (citrate, 42.1 hours; heparin, 24 hours; χ(2)=8.1; P=0.004). Considerable variation in filter life existed between patients, and between vascular access sites within patients. Safety end points were reached in one heparin and three citrate patients. CONCLUSION: Although the per-protocol results favoured citrate when it was actually delivered, the significant crossover between treatment arms hampered more definitive conclusions. Until further studies support improved patient outcomes, increased complexity and complications suggest that anticoagulation choice be made using patient-specific indications.

Magnesium flux during continuous venovenous haemodiafiltration with heparin and citrate anticoagulation.

OBJECTIVE: To describe magnesium flux and serum concentrations in ICU patients receiving continuous venovenous haemodiafiltration (CVVHDF). DESIGN: Samples were collected from 22 CVVHDF circuits using citrate anticoagulation solutions (Prismocitrate 10/2 and Prism0cal) and from 26 circuits using Hemosol B0 and heparin anticoagulation. CVVHDF prescription, magnesium supplementation and anticoagulation choice was by the treating intensivist. We analysed 334 sample sets consisting of arterial, prefilter and postfilter blood and effluent. Magnesium loss was calculated from an equation for conservation of mass, and arterial magnesium concentration was described by an equation for exponential decay. RESULTS: Using flow rates typical of adults receiving CVVHDF, we determined a median half-life for arterial magnesium concentration to decay to a new steady state of 4.73 hours (interquartile range [IQR], 3.73-7.32 hours). Median arterial magnesium concentration was 0.88mmol/L (IQR, 0.83-0.97mmol/L) in the heparin group and 0.79mmol/L (IQR, 0.69-0.91mmol/L) in the citrate group. Arterial magnesium concentrations fell below the reference range regularly in the citrate group and, when low, there was magnesium flux from dialysate to patient. Magnesium loss was greater in patients receiving citrate. CONCLUSIONS: Exponential decline in magnesium concentrations was sufficiently rapid that subtherapeutic serum magnesium concentrations may occur well before detection when once-daily sampling was used. Measurements should be interpreted with regard to timing of magnesium infusions. We suggest that continuous renal replacement therapy fluids with higher magnesium concentrations be introduced in the critical care setting.

Calcium flux in continuous venovenous haemodiafiltration with heparin and citrate anticoagulation.

BACKGROUND: Calcium chelation with citrate is an effective alternative to heparin for anticoagulation of the extracorporeal circuit during continuous venovenous haemodiafiltration (CVVHD-F). Calcium release occurs upon citrate metabolism; however, ultrafiltration of citrate-bound and free ions also occurs. OBJECTIVE: To quantify calcium loss and improve understanding of calcium homeostasis in CVVHD-F. METHODS: Calcium loss was prospectively quantified from heparinised and citrated circuits in consecutive intensive care patients requiring CVVHD-F. CVVHD-F prescription and anticoagulation choice was by the treating intensivist using commercial solutions (Gambro, Lundia, Sweden). Sample sets comprising arterial, prefilter and postfilter blood and an effluent sample were analysed for ionised total calcium (iCa(2+)) and magnesium levels. Flow rates were then used to calculate calcium flux. Citrate dose (predilution rate) and calcium replacement followed unit protocols to maintain a circuit iCa(2+) concentration of 0.3-0.5 mmol/L and an arterial iCa(2+) concentration of 0.8-1.1 mmol/L. RESULTS: 26 heparinised circuits and 22 citrated circuits in 13 patients were included; 334 sample sets were tested. For target extracorporeal blood flows of 200 mL/min, mean predilution Prismocitrate 10/2 flows were 1660 mL/h, delivering 2.42 mmol citrate per litre of blood. For heparin, mean predilution flows of Hemosol B0 were 2058mL/h. Mean calcium loss was 4.01 mmol/h from citrate anticoagulated circuits versus a gain of 0.24mmol/h from heparinised circuits (P < 0.001). Despite calcium replacement, citrate patients experienced a mean calcium loss of 1.12 mmol/h (SD, 0.70; 95% CI 1.0-1.22mmol/h; P < 0.001). Calculated effective diffusion volume (Q(E)) for calcium was closer to total blood water volume in heparin circuits and closer to plasma water volume in citrate circuits. CONCLUSIONS: Despite supplementation to maintain arterial iCa(2+) levels, citrate anticoagulation results in a net calcium deficit. An equation for estimating required citrate dose may allow revision of citrate dosing protocols.