4,750 research outputs found
Spectral imaging of thermal damage induced during microwave ablation in the liver
Induction of thermal damage to tissue through delivery of microwave energy is
frequently applied in surgery to destroy diseased tissue such as cancer cells.
Minimization of unwanted harm to healthy tissue is still achieved subjectively,
and the surgeon has few tools at their disposal to monitor the spread of the
induced damage. This work describes the use of optical methods to monitor the
time course of changes to the tissue during delivery of microwave energy in the
porcine liver. Multispectral imaging and diffuse reflectance spectroscopy are
used to monitor temporal changes in optical properties in parallel with thermal
imaging. The results demonstrate the ability to monitor the spatial extent of
thermal damage on a whole organ, including possible secondary effects due to
vascular damage. Future applications of this type of imaging may see the
multispectral data used as a feedback mechanism to avoid collateral damage to
critical healthy structures and to potentially verify sufficient application of
energy to the diseased tissue.Comment: 4pg,6fig. Copyright 2018 IEEE. Personal use of this material is
permitted. Permission from IEEE must be obtained for all other uses, in any
current or future media, including reprinting/republishing this material for
advertising or promotional purposes, creating new collective works, for
resale or redistribution to servers or lists, or reuse of any copyrighted
component of this work in other work
Computer-assisted polyp matching between optical colonoscopy and CT colonography: a phantom study
Potentially precancerous polyps detected with CT colonography (CTC) need to
be removed subsequently, using an optical colonoscope (OC). Due to large
colonic deformations induced by the colonoscope, even very experienced
colonoscopists find it difficult to pinpoint the exact location of the
colonoscope tip in relation to polyps reported on CTC. This can cause unduly
prolonged OC examinations that are stressful for the patient, colonoscopist and
supporting staff.
We developed a method, based on monocular 3D reconstruction from OC images,
that automatically matches polyps observed in OC with polyps reported on prior
CTC. A matching cost is computed, using rigid point-based registration between
surface point clouds extracted from both modalities. A 3D printed and painted
phantom of a 25 cm long transverse colon segment was used to validate the
method on two medium sized polyps. Results indicate that the matching cost is
smaller at the correct corresponding polyp between OC and CTC: the value is 3.9
times higher at the incorrect polyp, comparing the correct match between polyps
to the incorrect match. Furthermore, we evaluate the matching of the
reconstructed polyp from OC with other colonic endoluminal surface structures
such as haustral folds and show that there is a minimum at the correct polyp
from CTC.
Automated matching between polyps observed at OC and prior CTC would
facilitate the biopsy or removal of true-positive pathology or exclusion of
false-positive CTC findings, and would reduce colonoscopy false-negative
(missed) polyps. Ultimately, such a method might reduce healthcare costs,
patient inconvenience and discomfort.Comment: This paper was presented at the SPIE Medical Imaging 2014 conferenc
Convective infux/glymphatic system: tracers injected into the CSF enter and leave the brain along separate periarterial basement membrane pathways
Tracers injected into CSF pass into the brain alongside arteries and out again. This has been recently termed the "glymphatic system" that proposes tracers enter the brain along periarterial "spaces" and leave the brain along the walls of veins. The object of the present study is to test the hypothesis that: (1) tracers from the CSF enter the cerebral cortex along pial-glial basement membranes as there are no perivascular "spaces" around cortical arteries, (2) tracers leave the brain along smooth muscle cell basement membranes that form the Intramural Peri-Arterial Drainage (IPAD) pathways for the elimination of interstitial fluid and solutes from the brain. 2 μL of 100 μM soluble, fluorescent fixable amyloid β (Aβ) were injected into the CSF of the cisterna magna of 6-10 and 24-30 month-old male mice and their brains were examined 5 and 30 min later. At 5 min, immunocytochemistry and confocal microscopy revealed Aβ on the outer aspects of cortical arteries colocalized with α-2 laminin in the pial-glial basement membranes. At 30 min, Aβ was colocalised with collagen IV in smooth muscle cell basement membranes in the walls of cortical arteries corresponding to the IPAD pathways. No evidence for drainage along the walls of veins was found. Measurements of the depth of penetration of tracer were taken from 11 regions of the brain. Maximum depths of penetration of tracer into the brain were achieved in the pons and caudoputamen. Conclusions drawn from the present study are that tracers injected into the CSF enter and leave the brain along separate periarterial basement membrane pathways. The exit route is along IPAD pathways in which Aβ accumulates in cerebral amyloid angiopathy (CAA) in Alzheimer's disease. Results from this study suggest that CSF may be a suitable route for delivery of therapies for neurological diseases, including CAA
Uncertainty in multitask learning: joint representations for probabilistic MR-only radiotherapy planning
Multi-task neural network architectures provide a mechanism that jointly
integrates information from distinct sources. It is ideal in the context of
MR-only radiotherapy planning as it can jointly regress a synthetic CT (synCT)
scan and segment organs-at-risk (OAR) from MRI. We propose a probabilistic
multi-task network that estimates: 1) intrinsic uncertainty through a
heteroscedastic noise model for spatially-adaptive task loss weighting and 2)
parameter uncertainty through approximate Bayesian inference. This allows
sampling of multiple segmentations and synCTs that share their network
representation. We test our model on prostate cancer scans and show that it
produces more accurate and consistent synCTs with a better estimation in the
variance of the errors, state of the art results in OAR segmentation and a
methodology for quality assurance in radiotherapy treatment planning.Comment: Early-accept at MICCAI 2018, 8 pages, 4 figure
Breast Cancer Risk Assessment and Primary Prevention Advice in Primary Care: A Systematic Review of Provider Attitudes and Routine Behaviours
Implementing risk-stratified breast cancer screening is being considered internationally. It has been suggested that primary care will need to take a role in delivering this service, including risk assessment and provision of primary prevention advice. This systematic review aimed to assess the acceptability of these tasks to primary care providers. Five databases were searched up to July–August 2020, yielding 29 eligible studies, of which 27 were narratively synthesised. The review was pre-registered (PROSPERO: CRD42020197676). Primary care providers report frequently collecting breast cancer family history information, but rarely using quantitative tools integrating additional risk factors. Primary care providers reported high levels of discomfort and low confidence with respect to risk-reducing medications although very few reported doubts about the evidence base underpinning their use. Insufficient education/training and perceived discomfort conducting both tasks were notable barriers. Primary care providers are more likely to accept an increased role in breast cancer risk assessment than advising on risk-reducing medications. To realise the benefits of risk-based screening and prevention at a population level, primary care will need to proactively assess breast cancer risk and advise on risk-reducing medications. To facilitate this, adaptations to infrastructure such as integrated tools are necessary in addition to provision of education
Modeling, Reduction, and Control of a Helically Actuated Inertial Soft Robotic Arm via the Koopman Operator
Soft robots promise improved safety and capability over rigid robots when
deployed in complex, delicate, and dynamic environments. However, the infinite
degrees of freedom and highly nonlinear dynamics of these systems severely
complicate their modeling and control. As a step toward addressing this open
challenge, we apply the data-driven, Hankel Dynamic Mode Decomposition (HDMD)
with time delay observables to the model identification of a highly inertial,
helical soft robotic arm with a high number of underactuated degrees of
freedom. The resulting model is linear and hence amenable to control via a
Linear Quadratic Regulator (LQR). Using our test bed device, a dynamic,
lightweight pneumatic fabric arm with an inertial mass at the tip, we show that
the combination of HDMD and LQR allows us to command our robot to achieve
arbitrary poses using only open loop control. We further show that Koopman
spectral analysis gives us a dimensionally reduced basis of modes which
decreases computational complexity without sacrificing predictive power.Comment: Submitted to IEEE International Conference on Robotics and
Automation, 202
The challenges of deploying artificial intelligence models in a rapidly evolving pandemic
The COVID-19 pandemic, caused by the severe acute respiratory syndrome
coronavirus 2, emerged into a world being rapidly transformed by artificial
intelligence (AI) based on big data, computational power and neural networks.
The gaze of these networks has in recent years turned increasingly towards
applications in healthcare. It was perhaps inevitable that COVID-19, a global
disease propagating health and economic devastation, should capture the
attention and resources of the world's computer scientists in academia and
industry. The potential for AI to support the response to the pandemic has been
proposed across a wide range of clinical and societal challenges, including
disease forecasting, surveillance and antiviral drug discovery. This is likely
to continue as the impact of the pandemic unfolds on the world's people,
industries and economy but a surprising observation on the current pandemic has
been the limited impact AI has had to date in the management of COVID-19. This
correspondence focuses on exploring potential reasons behind the lack of
successful adoption of AI models developed for COVID-19 diagnosis and
prognosis, in front-line healthcare services. We highlight the moving clinical
needs that models have had to address at different stages of the epidemic, and
explain the importance of translating models to reflect local healthcare
environments. We argue that both basic and applied research are essential to
accelerate the potential of AI models, and this is particularly so during a
rapidly evolving pandemic. This perspective on the response to COVID-19, may
provide a glimpse into how the global scientific community should react to
combat future disease outbreaks more effectively.Comment: Accepted in Nature Machine Intelligenc
Correction of misaligned slices in multi-slice cardiovascular magnetic resonance using slice-to-volume registration
A popular technique to reduce respiratory motion for cardiovascular magnetic resonance is to perform a multi-slice acquisition in which a patient holds their breath multiple times during the scan. The feasibility of rigid slice-to-volume registration to correct for misalignments of slice stacks in such images due to differing breath-hold positions is explored. Experimental results indicate that slice-to-volume registration can compensate for the typical misalignments expected. Correction of slice misalignment results in anatomically more correct images, as well as improved left ventricular volume measurements. The interstudy reproducibility has also been improved reducing the number of samples needed for cardiac MR studies
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