46 research outputs found
Self-Supervised Discovery of Anatomical Shape Landmarks
Statistical shape analysis is a very useful tool in a wide range of medical
and biological applications. However, it typically relies on the ability to
produce a relatively small number of features that can capture the relevant
variability in a population. State-of-the-art methods for obtaining such
anatomical features rely on either extensive preprocessing or segmentation
and/or significant tuning and post-processing. These shortcomings limit the
widespread use of shape statistics. We propose that effective shape
representations should provide sufficient information to align/register images.
Using this assumption we propose a self-supervised, neural network approach for
automatically positioning and detecting landmarks in images that can be used
for subsequent analysis. The network discovers the landmarks corresponding to
anatomical shape features that promote good image registration in the context
of a particular class of transformations. In addition, we also propose a
regularization for the proposed network which allows for a uniform distribution
of these discovered landmarks. In this paper, we present a complete framework,
which only takes a set of input images and produces landmarks that are
immediately usable for statistical shape analysis. We evaluate the performance
on a phantom dataset as well as 2D and 3D images.Comment: Early accept at MICCAI 202
Probabilistic 3D surface reconstruction from sparse MRI information
Surface reconstruction from magnetic resonance (MR) imaging data is
indispensable in medical image analysis and clinical research. A reliable and
effective reconstruction tool should: be fast in prediction of accurate well
localised and high resolution models, evaluate prediction uncertainty, work
with as little input data as possible. Current deep learning state of the art
(SOTA) 3D reconstruction methods, however, often only produce shapes of limited
variability positioned in a canonical position or lack uncertainty evaluation.
In this paper, we present a novel probabilistic deep learning approach for
concurrent 3D surface reconstruction from sparse 2D MR image data and aleatoric
uncertainty prediction. Our method is capable of reconstructing large surface
meshes from three quasi-orthogonal MR imaging slices from limited training sets
whilst modelling the location of each mesh vertex through a Gaussian
distribution. Prior shape information is encoded using a built-in linear
principal component analysis (PCA) model. Extensive experiments on cardiac MR
data show that our probabilistic approach successfully assesses prediction
uncertainty while at the same time qualitatively and quantitatively outperforms
SOTA methods in shape prediction. Compared to SOTA, we are capable of properly
localising and orientating the prediction via the use of a spatially aware
neural network.Comment: MICCAI 202
Biomechanics-informed Neural Networks for Myocardial Motion Tracking in MRI
Image registration is an ill-posed inverse problem which often requires
regularisation on the solution space. In contrast to most of the current
approaches which impose explicit regularisation terms such as smoothness, in
this paper we propose a novel method that can implicitly learn
biomechanics-informed regularisation. Such an approach can incorporate
application-specific prior knowledge into deep learning based registration.
Particularly, the proposed biomechanics-informed regularisation leverages a
variational autoencoder (VAE) to learn a manifold for biomechanically plausible
deformations and to implicitly capture their underlying properties via
reconstructing biomechanical simulations. The learnt VAE regulariser then can
be coupled with any deep learning based registration network to regularise the
solution space to be biomechanically plausible. The proposed method is
validated in the context of myocardial motion tracking on 2D stacks of cardiac
MRI data from two different datasets. The results show that it can achieve
better performance against other competing methods in terms of motion tracking
accuracy and has the ability to learn biomechanical properties such as
incompressibility and strains. The method has also been shown to have better
generalisability to unseen domains compared with commonly used L2
regularisation schemes.Comment: The paper is early accepted by MICCAI 202
Human attentionâinspired volume reconstruction method on serial section electron microscopy images
Antibacterial and antifungal activities from leaf extracts of Cassia fistula l.: An ethnomedicinal plant
This study was carried out with an objective to investigate the antibacterial and antifungal potentials of leaves of Cassia fistula Linn. The aim of the study is to assess the antimicrobial activity and to determine the zone of inhibition of extracts on some bacterial and fungal strains. In the present study, the microbial activity of hydroalcohol extracts of leaves of Cassia fistula Linn. (an ethnomedicinal plant) was evaluated for potential antimicrobial activity against medically important bacterial and fungal strains. The antimicrobial activity was determined in the extracts using agar disc diffusion method. The antibacterial and antifungal activities of extracts (5, 25, 50, 100, 250 ÎŒg/ml) of Cassia fistula were tested against two Gram-positiveâStaphylococcus aureus, Streptococcus pyogenes; two Gram-negativeâEscherichia coli, Pseudomonas aeruginosa human pathogenic bacteria; and three fungal strainsâAspergillus niger, Aspergillus clavatus, Candida albicans. Zone of inhibition of extracts were compared with that of different standards like ampicillin, ciprofloxacin, norfloxacin, and chloramphenicol for antibacterial activity and nystatin and griseofulvin for antifungal activity. The results showed that the remarkable inhibition of the bacterial growth was shown against the tested organisms. The phytochemical analyses of the plants were carried out. The microbial activity of the Cassia fistula was due to the presence of various secondary metabolites. Hence, these plants can be used to discover bioactive natural products that may serve as leads in the development of new pharmaceuticals research activities