22,906 research outputs found
Simultaneous lesion and neuroanatomy segmentation in Multiple Sclerosis using deep neural networks
Segmentation of both white matter lesions and deep grey matter structures is
an important task in the quantification of magnetic resonance imaging in
multiple sclerosis. Typically these tasks are performed separately: in this
paper we present a single segmentation solution based on convolutional neural
networks (CNNs) for providing fast, reliable segmentations of multimodal
magnetic resonance images into lesion classes and normal-appearing grey- and
white-matter structures. We show substantial, statistically significant
improvements in both Dice coefficient and in lesion-wise specificity and
sensitivity, compared to previous approaches, and agreement with individual
human raters in the range of human inter-rater variability. The method is
trained on data gathered from a single centre: nonetheless, it performs well on
data from centres, scanners and field-strengths not represented in the training
dataset. A retrospective study found that the classifier successfully
identified lesions missed by the human raters.
Lesion labels were provided by human raters, while weak labels for other
brain structures (including CSF, cortical grey matter, cortical white matter,
cerebellum, amygdala, hippocampus, subcortical GM structures and choroid
plexus) were provided by Freesurfer 5.3. The segmentations of these structures
compared well, not only with Freesurfer 5.3, but also with FSL-First and
Freesurfer 6.0
Robust Representation Learning for Unreliable Partial Label Learning
Partial Label Learning (PLL) is a type of weakly supervised learning where
each training instance is assigned a set of candidate labels, but only one
label is the ground-truth. However, this idealistic assumption may not always
hold due to potential annotation inaccuracies, meaning the ground-truth may not
be present in the candidate label set. This is known as Unreliable Partial
Label Learning (UPLL) that introduces an additional complexity due to the
inherent unreliability and ambiguity of partial labels, often resulting in a
sub-optimal performance with existing methods. To address this challenge, we
propose the Unreliability-Robust Representation Learning framework (URRL) that
leverages unreliability-robust contrastive learning to help the model fortify
against unreliable partial labels effectively. Concurrently, we propose a dual
strategy that combines KNN-based candidate label set correction and
consistency-regularization-based label disambiguation to refine label quality
and enhance the ability of representation learning within the URRL framework.
Extensive experiments demonstrate that the proposed method outperforms
state-of-the-art PLL methods on various datasets with diverse degrees of
unreliability and ambiguity. Furthermore, we provide a theoretical analysis of
our approach from the perspective of the expectation maximization (EM)
algorithm. Upon acceptance, we pledge to make the code publicly accessible
Decomposition-based Generation Process for Instance-Dependent Partial Label Learning
Partial label learning (PLL) is a typical weakly supervised learning problem,
where each training example is associated with a set of candidate labels among
which only one is true. Most existing PLL approaches assume that the incorrect
labels in each training example are randomly picked as the candidate labels and
model the generation process of the candidate labels in a simple way. However,
these approaches usually do not perform as well as expected due to the fact
that the generation process of the candidate labels is always
instance-dependent. Therefore, it deserves to be modeled in a refined way. In
this paper, we consider instance-dependent PLL and assume that the generation
process of the candidate labels could decompose into two sequential parts,
where the correct label emerges first in the mind of the annotator but then the
incorrect labels related to the feature are also selected with the correct
label as candidate labels due to uncertainty of labeling. Motivated by this
consideration, we propose a novel PLL method that performs Maximum A
Posterior(MAP) based on an explicitly modeled generation process of candidate
labels via decomposed probability distribution models. Experiments on benchmark
and real-world datasets validate the effectiveness of the proposed method
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