An Inter-observer Study to Determine Radiotherapy Planning Target Volumes for Recurrent Gynaecological Cancer Comparing Magnetic Resonance Imaging Only With Computed Tomography-Magnetic Resonance Imaging

AIMS

Target delineation uncertainty is arguably the largest source of geometric uncertainty in radiotherapy. Several factors can affect it, including the imaging modality used for delineation. It is accounted for by applying safety margins to the target to produce a planning target volume (PTV), to which treatments are designed. To determine the margin, the delineation uncertainty is measured as the delineation error, and then a margin recipe used. However, there is no published evidence of such analysis for recurrent gynaecological cancers (RGC). The aims of this study were first to quantify the delineation uncertainty for RGC gross tumour volumes (GTVs) and to calculate the associated PTV margins and then to quantify the difference in GTV, delineation uncertainty and PTV margin, between a computed tomography-magnetic resonance imaging (CT-MRI) and MRI workflow.

MATERIALS AND METHODS

Seven clinicians delineated the GTV for 20 RGC tumours on co-registered CT and MRI datasets (CT-MRI) and on MRI alone. The delineation error, the standard deviation of distances from each clinician's outline to a reference, was measured and the required PTV margin determined. Differences between using CT-MRI and MRI alone were assessed.

RESULTS

The overall delineation error and the resulting margin were 3.1 mm and 8.5 mm, respectively, for CT-MRI, reducing to 2.5 mm and 7.1 mm, respectively, for MRI alone. Delineation errors and therefore the theoretical margins, varied widely between patients. MRI tumour volumes were on average 15% smaller than CT-MRI tumour volumes.

DISCUSSION

This study is the first to quantify delineation error for RGC tumours and to calculate the corresponding PTV margin. The determined margins were larger than those reported in the literature for similar patients, bringing into question both current margins and margin calculation methods. The wide variation in delineation error between these patients suggests that applying a single population-based margin may result in PTVs that are suboptimal for many. Finally, the reduced tumour volumes and safety margins suggest that patients with RGC may benefit from an MRI-only treatment workflow.

Preferential grazing and repackaging of small polyethylene microplastic particles (≤ 5 μm) by the ciliate Sterkiella sp

Microplastic (MP) particles are pollutants of global concern and are ubiquitously distributed in the ocean by physical and biological processes. It has been shown that zooplankton can ingest MP yet the interaction between ciliates and MP is still poorly understood. The discrimination and preferential uptake of MP rather than algal prey by ciliates was assessed in this study. The ciliate Sterkiella sp. was fed a diet that consisted of only Isochrysis galbana or a mixture of the same algae and similarly sized polyethylene beads in a 1:3 ratio. Significant, preferential MP grazing was observed in the Plastic-Algae treatment, which is the first reported evidence of proto-zooplankton preferentially ingesting MP over algal food. The mixed treatment contained fecal pellets with embedded MP. Preferential uptake of MP suggests that Sterkiella sp. is capable of ingesting and then "repackaging" MP that would otherwise be too small for larger taxa. This process would thus offer a mechanism for the reintroduction of MP into different compartments of the marine food web. As a consequence, it is necessary to account for small-sized MP (<5 μm) particles, that may have additional and yet unknown, impacts on marine food webs.

Impact of catheter ablation on HFpEF in people with comorbid atrial fibrillation and HFpEF using invasive haemodynamic testing

Background

The impact of catheter ablation (CA) for atrial fibrillation (AF) in patients with heart failure with preserved ejection fraction (HFpEF) is unknown.

Objectives

To determine whether CA for AF reverses adverse haemodynamic changes associated with HFpEF.

Methods

Consecutive consenting patients with EF ≥50% scheduled for index CA underwent baseline exercise right heart catheterisation (exRHC), cardiac output (CO) measurement, cardiac MRI, echocardiogram, QOL questionnaires and BNP testing. HFpEF was defined by resting pulmonary capillary wedge pressure (PCWP) ≥15mmHg or peak exercise PCWP ≥25 mmHg during exRHC. Patients with HFpEF were offered follow-up exRHC ≥6 months post-CA.

Results

Of 252 patients scheduled for CA between April 2017 and Sept 2019, 131 (51.9%) qualified for inclusion, 65 (49.6%) consented to exRHC and 11 (16.9%) were excluded due to a subsequent decrease in EF (10) and uncontrolled hypertension (1). Fifty-four underwent exRHC, with 35 (65%) meeting criteria for HFpEF. Of them 26 (74.3%) who underwent CA, 20 (77%) had a follow up exRHC at 12±6 months follow-up, showing an overall decrease in peak exercise PCWP from 30.3±4.2 to 26.8±4.7 mmHg (p&lt;0.05). Patients without arrhythmia recurrence showed significant improvements in peak exercise PCWP (29.2±3.7 to 22.9±2.0 mmHg (p&lt;0.01). Their cardiac output increased from 10.3±3.0 to 12.1±4.0 mmHg p=0.1), and BNP decreased from (94.6±101.6 to 38.0±34.0 mmHg (p=0.06),whereas those with arrhythmia recurrence did not. Overall, 9 patients (45.0%) no longer met criteria for HFpEF.

Conclusion

There is a high prevalence of HFpEF in people referred for AF ablation. Successful CA for AF reverses the adverse haemodynamic changes associated with HFpEF

Changes in PCWP following AF ablation

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): NHMRC, NHF, RACP

Considerations for Antiplatelet Management of Carotid Stenting in the Setting of Mechanical Thrombectomy: A Delphi Consensus Statement

BACKGROUND AND PURPOSE

There are only few data and lack of consensus regarding antiplatelet management for carotid stent placement in the setting of endovascular stroke treatment. We aimed to develop a consensus-based algorithm for antiplatelet management in acute ischemic stroke patients undergoing endovascular treatment and simultaneous emergent carotid stent placement.

MATERIALS AND METHODS

We performed a literature search and a modified Delphi approach used Web-based questionnaires that were sent in several iterations to an international multidisciplinary panel of 19 neurointerventionalists from 7 countries. The first round included open-ended questions and formed the basis for subsequent rounds, in which closed-ended questions were used. Participants continuously received feedback on the results from previous rounds. Consensus was defined as agreement of ≥70% for binary questions and agreement of ≥50% for questions with >2 answer options. The results of the Delphi process were then summarized in a draft manuscript that was circulated among the panel members for feedback.

RESULTS

A total of 5 Delphi rounds were performed. Panel members preferred a single intravenous aspirin bolus or, in jurisdictions in which intravenous aspirin is not available, a glycoprotein IIb/IIIa receptor inhibitor as intraprocedural antiplatelet regimen and a combination therapy of oral aspirin and a P2Y12 inhibitor in the postprocedural period. There was no consensus on the role of platelet function testing in the postprocedural period.

CONCLUSIONS

More and better data on antiplatelet management for carotid stent placement in the setting of endovascular treatment are urgently needed. Panel members preferred intravenous aspirin or, alternatively, a glycoprotein IIb/IIIa receptor inhibitor as an intraprocedural antiplatelet agent, followed by a dual oral regimen of aspirin and a P2Y12 inhibitor in the postprocedural period.

Antiplatelet Management for Stent-Assisted Coiling and Flow Diversion of Ruptured Intracranial Aneurysms: A DELPHI Consensus Statement

BACKGROUND AND PURPOSE

There is a paucity of data regarding antiplatelet management strategies in the setting of stent-assisted coiling/flow diversion for ruptured intracranial aneurysms. This study aimed to identify current challenges in antiplatelet management during stent-assisted coiling/flow diversion for ruptured intracranial aneurysms and to outline possible antiplatelet management strategies.

MATERIALS AND METHODS

The modified DELPHI approach with an on-line questionnaire was sent in several iterations to an international, multidisciplinary panel of 15 neurointerventionalists. The first round consisted of open-ended questions, followed by closed-ended questions in the subsequent rounds. Responses were analyzed in an anonymous fashion and summarized in the final manuscript draft. The statement received endorsement from the World Federation of Interventional and Therapeutic Neuroradiology, the Japanese Society for Neuroendovascular Therapy, and the Chinese Neurosurgical Society.

RESULTS

Data were collected from December 9, 2019, to March 13, 2020. Panel members achieved consensus that platelet function testing may not be necessary and that antiplatelet management for stent-assisted coiling and flow diversion of ruptured intracranial aneurysms can follow the same principles. Preprocedural placement of a ventricular drain was thought to be beneficial in cases with a high risk of hydrocephalus. A periprocedural dual, intravenous, antiplatelet regimen with aspirin and a glycoprotein IIb/IIIa inhibitor was preferred as a standard approach. The panel agreed that intravenous medication can be converted to oral aspirin and an oral P2Y12 inhibitor within 24 hours after the procedure.

CONCLUSIONS

More and better data on antiplatelet management of patients with ruptured intracranial aneurysms undergoing stent-assisted coiling or flow diversion are urgently needed. Panel members in this DELPHI consensus study preferred a periprocedural dual-antiplatelet regimen with aspirin and a glycoprotein IIb/IIIa inhibitor.

The effect of an ultrasound-activated needle tip tracker needle on the performance of sciatic nerve block on a soft embalmed Thiel cadaver

In this study, we measured the performance of medical students and anaesthetists using a new tracker needle during simulated sciatic nerve block on soft embalmed cadavers. The tracker needle incorporates a piezo element near its tip that generates an electrical signal in response to insonation. A circle, superimposed on the ultrasound image surrounding the needle tip, changes size and colour according to the position of the piezo element within the ultrasound beam. Our primary objective was to compare sciatic block performance with the tracker switched on and off. Our secondary objectives were to record psychometrics, procedure efficiency, participant self-regulation and focused attention using eye-tracking technology. Our primary outcome measures were the number of steps successfully performed and the number of errors committed during each block. Videos were scored by trained experts using validated checklists. Sequential tracker activation and deactivation was randomised equally within subjects. With needle activation, steps improved in 10 (25%) subjects and errors reduced in six (15%) subjects. The most important steps were: needle tip identification before injection, OR (95%CI) 2.12 (1.61-2.80; p < 0.001); and needle tip identification before advance of the needle, 1.80 (1.36-2.39; p < 0.001). The most important errors were: failure to identify the needle tip before injection, 2.40 (1.78-3.24; p < 0.001); and failure to quickly regain needle tip position when tip visibility was lost, 2.03 (1.5-2.75; p < 0.001). In conclusion, needle-tracking technology improved performance in a quarter of subjects.

Application of spike sorting algorithm to neuronal signals originated from boron doped diamond micro-electrode arrays

In this work we report on the implementation of methods for data processing signals from microelectrode arrays (MEA) and the application of these methods for signals originated from two types of MEAs to detect putative neurons and sort them into subpopulations. We recorded electrical signals from firing neurons using titanium nitride (TiN) and boron doped diamond (BDD) MEAs. In previous research, we have shown that these methods have the capacity to detect neurons using commercially-available TiN-MEAs. We have managed to cultivate and record hippocampal neurons for the first time using a newly developed custom-made multichannel BDD-MEA with 20 recording sites. We have analysed the signals with the algorithms developed and employed them to inspect firing bursts and enable spike sorting. We did not observe any significant difference between BDD- and TiN-MEAs over the parameters, which estimated spike shape variability per each detected neuron. This result supports the hypothesis that we have detected real neurons, rather than noise, in the BDD-MEA signal. BDD materials with suitable mechanical, electrical and biocompatibility properties have a large potential in novel therapies for treatments of neural pathologies, such as deep brain stimulation in Parkinson's disease.

0886 Changes in Parent Knowledge and Self-Efficacy and Association With Adherence Following the Steps Towards Achieving Restful Sleep (STARS) Pediatric PAP Therapy Desensitization Program

Introduction

Obstructive sleep apnea (OSA) presents in 2-5 % of youth and has been consistently linked to sleepiness, cognitive deficits, behavior difficulties, and cardiovascular morbidity. PAP effectively treats OSA, however, nonadherence is the most common cause of PAP treatment failure in children. Few adherence interventions have been empirically studied for youth with OSA. The STARS (Steps Towards Achieving Restful Sleep) Clinic is a behavioral program to optimize child tolerance to PAP therapy through a parent class, and in vivo practice. The goal of the study was to examine parent knowledge and self-efficacy following participation in STARS, and associations with subsequent PAP adherence.

Methods

A retrospective chart review was conducted for patients in the STARS program. Items queried included patient demographics, diagnostic and treatment characteristics, pre- and post- STARS responses to a parent self-efficacy and knowledge questionnaire, and polysomnography and PAP adherence data. Paired-samples t-tests examined changes in parent self-efficacy and knowledge pre- to post STARS, and regression analyses examined associations between self-efficacy and knowledge with demographics, treatment-related characteristics, and PAP adherence.

Results

130 patients completed the STARS program from October 2016 to February 2019. Participants were 8.3 years old ±6.3, 63% male, 57% white, 33% Hispanic, with severe OSA (OAHI =22 ±33). Most participants (87%) had at least one medical comorbidity (e.g, Down Syndrome, 41%). Both parent knowledge and self-efficacy increased significantly from pre- to post- STARS. Approximately 60% of patients were adherent following STARS (defined as ≥4 h use and ≥70% of days used). Higher post- knowledge, but not efficacy score, was significantly associated with better PAP adherence.

Conclusion

Parent knowledge and self-efficacy for PAP improved following the STARS program, and greater knowledge was associated with better adherence. Future research evaluating the efficacy and effectiveness of the STARS program is needed but preliminary evidence suggests it may be a promising model for improving youth PAP adherence.

Support

None

Persistence and compliance with osteoporosis therapies among postmenopausal women in the UK Clinical Practice Research Datalink

Gaining full benefits from osteoporosis medications requires long-term treatment. Investigating the real-world persistence of women receiving osteoporosis medications in the UK, we found that most patients stop treatment within a year. To prevent osteoporotic fragility fractures, long-term treatment persistence must be improved.

INTRODUCTION

Persistence with osteoporosis therapies has historically been poor. To treat this chronic and progressive disease, it is essential that patients receive the full benefit of these medications. We estimated persistence and compliance with osteoporosis therapies in a large sample of postmenopausal women in the UK.

METHODS

Data were obtained from the Clinical Practice Research Datalink for all women aged 50 years and over or women with early menopause, who received at least one prescription in primary care for any licensed osteoporosis therapy between January 1, 2010 and December 31, 2015. Persistence and compliance at 24 months (primary objective) and at 5 years (exploratory objective) were estimated in three patient cohorts: "All Patients," "Naïve Patients," and "Drug-Specific."

RESULTS

The All Patients cohort included 72,256 women. Persistence with any therapy was 56.1%, 43.6%, 36.4%, and 31.0% at 6, 12, 18, and 24 months, respectively, and 23.2% and 13.1% at 3 years and 5 years, respectively. Patients were generally more persistent and compliant if evaluated from their first exposure to osteoporosis therapy (Naïve Patients cohort). In the drug-specific analysis, 64% of patients receiving denosumab (administered subcutaneously every 6 months) were persistent at 24 months compared with 28% and 23% of those taking oral bisphosphonates and intravenous bisphosphonates, respectively.

CONCLUSIONS

Only about one in three patients who received osteoporosis therapy continued to be on treatment after 2 years. There is a need to improve persistence with osteoporosis therapy, especially for high-risk patients.