Analysing and quantifying visual experience in medical imaging

Healthcare professionals increasingly view medical images and videos in a variety of environments. The perception and interpretation of medical visual information across all specialties, career stages, and practice settings are critical to patient care and safety. However, medical images and videos are not self-explanatory and thus need to be interpreted by humans, who are prone to errors caused by the inherent limitations of the human visual system. It is essential to understand how medical experts perceive visual content, and use this knowledge to develop new solutions to improve clinical practice. Progress has been made in the literature towards such understanding, however studies remain limited. This thesis investigates two aspects of human visual experience in medical imaging, i.e., visual quality assessment and visual attention. Visual quality assessment is important as diverse visual signal distortion may arise in medical imaging and affect the perceptual quality of visual content, and therefore potentially impact the diagnosis accuracy. We adapted existing qualitative and quantitative methods to evaluate the quality of distorted medical videos. We also analysed the impact of medical specialty on visual perception and found significant differences between specialty groups, e.g., sonographers were in general more bothered by visual distortions than radiologists. Visual attention has been studied in medical imaging using eye-tracking technology. In this thesis, we firstly investigated gaze allocation with radiologists analysing two-view mammograms and secondly assessed the impact of expertise and experience on gaze behaviour. We also evaluated to what extent state-of-the-art visual attention models can predict radiologists’ gaze behaviour and showed the limitations of existing models. This thesis provides new experimental designs and statistical processes to evaluate the perception of medical images and videos, which can be used to optimise the visual experience of image readers in clinical practice

The Role of Plasma Extracellular Vesicles and Procoagulant Phospholipid Activity in Venous Thromboembolism

Venous thromboembolism (VTE) is the formation of a blood clot in, most commonly, the deep veins of the lower extremities and the pulmonary circulation. VTE is a prevalent disease associated with severe short- and long-term complications. Negatively charged procoagulant phospholipids (PPL), and phosphatidylserine (PS) in particular, are vital to efficient coagulation activation, and found expressed on the surface of extracellular vesicles (EVs) and activated platelets. The overall aim of the present thesis was to develop an easily available and reproducible FXa-dependent clotting assay to measure PPL activity in plasma, and further use the assay to investigate the association between plasma PPL activity and the risk of VTE. In paper I, we investigate the impact of several pre-analytical conditions on EV concentration and size measured by Nanoparticle Tracking Analysis (NTA) and scanning electron microscopy (SEM). In paper II, we developed a modified FXa-dependent clotting assay by substituting the chemically phospholipid depleted plasma with PPL-depleted plasma obtained by ultracentrifugation. In paper III, we used our modified PPL assay to investigate the association between PPL clotting time (PPLCT) and the risk of incident VTE in a nested case-control study derived from a population based cohort (the Tromsø study). Previous studies have suggest that statin treatment reduced the risk of recurrent VTE. In paper IV, we investigated the impact of statin treatment (rosuvastatin) on PPL activity, using the modified PPL assay and plasma samples from the STAtins Reduce Thrombophilia trial. The impact of pre-analytical conditions (i.e. anticoagulants, centrifugation protocols, and fasting status) on EV measurements was demonstrated, and the obstacle of post-prandial lipoproteins interfering with NTA analysis was particularly highlighted. We found that the modified PPL assay displayed similar sensitivity and reproducibility compared to commercial assays based on chemically phospholipid-depleted plasma. We observed an inverse association between plasma PPLCT, assessed by the modified assay, and the risk of future VTE in a population-based nested case-control study. Additionally, rosuvastatin treatment caused a substantial decrease in plasma PPL activity in subjects with a history of VTE. The development of the modified PPL assay enabled us to perform high-quality measurements in large-scale studies. The inverse association between PPLCT and VTE risk supports an important role of plasma PPL in the pathogenesis of VTE and may partly explain the reduced risk of VTE recurrence observed by statin treatment

The impact of AI on radiographic image reporting – perspectives of the UK reporting radiographer population

Background: It is predicted that medical imaging services will be greatly impacted by AI in the future. Developments in computer vision have allowed AI to be used for assisted reporting. Studies have investigated radiologists' opinions of AI for image interpretation (Huisman et al., 2019 a/b) but there remains a paucity of information in reporting radiographers' opinions on this topic.Method: A survey was developed by AI expert radiographers and promoted via LinkedIn/Twitter and professional networks for radiographers from all specialities in the UK. A sub analysis was performed for reporting radiographers only.Results: 411 responses were gathered to the full survey (Rainey et al., 2021) with 86 responses from reporting radiographers included in the data analysis. 10.5% of respondents were using AI tools? as part of their reporting role. 59.3% and 57% would not be confident in explaining an AI decision to other healthcare practitioners and 'patients and carers' respectively. 57% felt that an affirmation from AI would increase confidence in their diagnosis. Only 3.5% would not seek second opinion following disagreement from AI. A moderate level of trust in AI was reported: mean score = 5.28 (0 = no trust; 10 = absolute trust). 'Overall performance/accuracy of the system', 'visual explanation (heatmap/ROI)', 'Indication of the confidence of the system in its diagnosis' were suggested as measures to increase trust.Conclusion: AI may impact reporting professionals' confidence in their diagnoses. Respondents are not confident in explaining an AI decision to key stakeholders. UK radiographers do not yet fully trust AI. Improvements are suggested

An evaluation of a training tool and study day in chest image interpretation

Background: With the use of expert consensus a digital tool was developed by the research team which proved useful when teaching radiographers how to interpret chest images. The training tool included A) a search strategy training tool and B) an educational tool to communicate the search strategies using eye tracking technology. This training tool has the potential to improve interpretation skills for other healthcare professionals.Methods: To investigate this, 31 healthcare professionals i.e. nurses and physiotherapists, were recruited and participants were randomised to receive access to the training tool (intervention group) or not to have access to the training tool (control group) for a period of 4-6 weeks. Participants were asked to interpret different sets of 20 chest images before and after the intervention period. A study day was then provided to all participants following which participants were again asked to interpret a different set of 20 chest images (n=1860). Each participant was asked to complete a questionnaire on their perceptions of the training provided. Results: Data analysis is in progress. 50% of participants did not have experience in image interpretation prior to the study. The study day and training tool were useful in improving image interpretation skills. Participants perception of the usefulness of the tool to aid image interpretation skills varied among respondents.Conclusion: This training tool has the potential to improve patient diagnosis and reduce healthcare costs

12th Annual Student Academic Conference: Showcasing the Work and Talents of MSUM Students

Minnesota State University Moorhead Student Academic Conference abstract book.https://red.mnstate.edu/sac-book/1011/thumbnail.jp

Anthropometric study to update minimum aircraft seating standards

This study was initiated by the Joint Aviation Authorities (JAA) under UK Civil Aviation Authority funding. The study was undertaken against a background trend of generally increasing body dimensions within the European population. This trend, when combined with an increasing number of longer duration flights and high density seating, prompted the need for a wide-ranging review of published anthropometric data that would guide JAA when considering the need for any regulation in this area. It should be noted that this report concentrates on the safety issues associated with seating arrangements. The specific aim is to ensure that seating standards are such that passengers would be able to quickly evacuate an aircraft in the event of an emergency. Thus, the study considers seating accommodation against expected population body dimensions. Software modelling has been used to make an initial assessment of the relationship between seating dimensions and evacuation difficulties. The health implications of aircraft seating are also considered. However, the comfort aspects of aircraft seating did not form part of the research study