1,989 research outputs found
Elastic Registration of Geodesic Vascular Graphs
Vascular graphs can embed a number of high-level features, from morphological
parameters, to functional biomarkers, and represent an invaluable tool for
longitudinal and cross-sectional clinical inference. This, however, is only
feasible when graphs are co-registered together, allowing coherent multiple
comparisons. The robust registration of vascular topologies stands therefore as
key enabling technology for group-wise analyses. In this work, we present an
end-to-end vascular graph registration approach, that aligns networks with
non-linear geometries and topological deformations, by introducing a novel
overconnected geodesic vascular graph formulation, and without enforcing any
anatomical prior constraint. The 3D elastic graph registration is then
performed with state-of-the-art graph matching methods used in computer vision.
Promising results of vascular matching are found using graphs from synthetic
and real angiographies. Observations and future designs are discussed towards
potential clinical applications
Differentiable Topology-Preserved Distance Transform for Pulmonary Airway Segmentation
Detailed pulmonary airway segmentation is a clinically important task for
endobronchial intervention and treatment of peripheral located lung cancer
lesions. Convolutional Neural Networks (CNNs) are promising tools for medical
image analysis but have been performing poorly for cases when existing a
significant imbalanced feature distribution, which is true for the airway data
as the trachea and principal bronchi dominate most of the voxels whereas the
lobar bronchi and distal segmental bronchi occupy a small proportion. In this
paper, we propose a Differentiable Topology-Preserved Distance Transform
(DTPDT) framework to improve the performance of airway segmentation. A
Topology-Preserved Surrogate (TPS) learning strategy is first proposed to
balance the training progress within-class distribution. Furthermore, a
Convolutional Distance Transform (CDT) is designed to identify the breakage
phenomenon with superior sensitivity and minimize the variation of the distance
map between the predictionand ground-truth. The proposed method is validated
with the publically available reference airway segmentation datasets. The
detected rate of branch and length on public EXACT'09 and BAS datasets are
82.1%/79.6% and 96.5%/91.5% respectively, demonstrating the reliability and
efficiency of the method in terms of improving the topology completeness of the
segmentation performance while maintaining the overall topology accuracy.Comment: 10 page
Multi-site, Multi-domain Airway Tree Modeling (ATM'22): A Public Benchmark for Pulmonary Airway Segmentation
Open international challenges are becoming the de facto standard for
assessing computer vision and image analysis algorithms. In recent years, new
methods have extended the reach of pulmonary airway segmentation that is closer
to the limit of image resolution. Since EXACT'09 pulmonary airway segmentation,
limited effort has been directed to quantitative comparison of newly emerged
algorithms driven by the maturity of deep learning based approaches and
clinical drive for resolving finer details of distal airways for early
intervention of pulmonary diseases. Thus far, public annotated datasets are
extremely limited, hindering the development of data-driven methods and
detailed performance evaluation of new algorithms. To provide a benchmark for
the medical imaging community, we organized the Multi-site, Multi-domain Airway
Tree Modeling (ATM'22), which was held as an official challenge event during
the MICCAI 2022 conference. ATM'22 provides large-scale CT scans with detailed
pulmonary airway annotation, including 500 CT scans (300 for training, 50 for
validation, and 150 for testing). The dataset was collected from different
sites and it further included a portion of noisy COVID-19 CTs with ground-glass
opacity and consolidation. Twenty-three teams participated in the entire phase
of the challenge and the algorithms for the top ten teams are reviewed in this
paper. Quantitative and qualitative results revealed that deep learning models
embedded with the topological continuity enhancement achieved superior
performance in general. ATM'22 challenge holds as an open-call design, the
training data and the gold standard evaluation are available upon successful
registration via its homepage.Comment: 32 pages, 16 figures. Homepage: https://atm22.grand-challenge.org/.
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Label Refinement Network from Synthetic Error Augmentation for Medical Image Segmentation
Deep convolutional neural networks for image segmentation do not learn the
label structure explicitly and may produce segmentations with an incorrect
structure, e.g., with disconnected cylindrical structures in the segmentation
of tree-like structures such as airways or blood vessels. In this paper, we
propose a novel label refinement method to correct such errors from an initial
segmentation, implicitly incorporating information about label structure. This
method features two novel parts: 1) a model that generates synthetic structural
errors, and 2) a label appearance simulation network that produces synthetic
segmentations (with errors) that are similar in appearance to the real initial
segmentations. Using these synthetic segmentations and the original images, the
label refinement network is trained to correct errors and improve the initial
segmentations. The proposed method is validated on two segmentation tasks:
airway segmentation from chest computed tomography (CT) scans and brain vessel
segmentation from 3D CT angiography (CTA) images of the brain. In both
applications, our method significantly outperformed a standard 3D U-Net and
other previous refinement approaches. Improvements are even larger when
additional unlabeled data is used for model training. In an ablation study, we
demonstrate the value of the different components of the proposed method
Statistical Shape Modelling and Segmentation of the Respiratory Airway
The human respiratory airway consists of the upper (nasal cavity, pharynx) and the lower (trachea, bronchi) respiratory tracts. Accurate segmentation of these two airway tracts can lead to better diagnosis and interpretation of airway-specific diseases, and lead to improvement in the localization of abnormal metabolic or pathological sites found within and/or surrounding the respiratory regions. Due to the complexity and the variability displayed in the anatomical structure of the upper respiratory airway along with the challenges in distinguishing the nasal cavity from non-respiratory regions such as the paranasal sinuses, it is difficult for existing algorithms to accurately segment the upper airway without manual intervention. This thesis presents an implicit non-parametric framework for constructing a statistical shape model (SSM) of the upper and lower respiratory tract, capable of distinct shape generation and be adapted for segmentation. An SSM of the nasal cavity was successfully constructed using 50 nasal CT scans. The performance of the SSM was evaluated for compactness, specificity and generality. An averaged distance error of 1.47 mm was measured for the generality assessment. The constructed SSM was further adapted with a modified locally constrained random walk algorithm to segment the nasal cavity. The proposed algorithm was evaluated on 30 CT images and outperformed comparative state-of-the-art and conventional algorithms. For the lower airway, a separate algorithm was proposed to automatically segment the trachea and bronchi, and was designed to tolerate the image characteristics inherent in low-contrast CT images. The algorithm was evaluated on 20 clinical low-contrast CT from PET-CT patient studies and demonstrated better performance (87.1±2.8 DSC and distance error of 0.37±0.08 mm) in segmentation results against comparative state-of-the-art algorithms
Human treelike tubular structure segmentation: A comprehensive review and future perspectives
Various structures in human physiology follow a treelike morphology, which often expresses complexity at very fine scales. Examples of such structures are intrathoracic airways, retinal blood vessels, and hepatic blood vessels. Large collections of 2D and 3D images have been made available by medical imaging modalities such as magnetic resonance imaging (MRI), computed tomography (CT), Optical coherence tomography (OCT) and ultrasound in which the spatial arrangement can be observed. Segmentation of these structures in medical imaging is of great importance since the analysis of the structure provides insights into disease diagnosis, treatment planning, and prognosis. Manually labelling extensive data by radiologists is often time-consuming and error-prone. As a result, automated or semi-automated computational models have become a popular research field of medical imaging in the past two decades, and many have been developed to date. In this survey, we aim to provide a comprehensive review of currently publicly available datasets, segmentation algorithms, and evaluation metrics. In addition, current challenges and future research directions are discussed
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