2,058 research outputs found
Similarity enhancement for automatic segmentation of cardiac structures in computed tomography volumes.
International audienceThe aim of this research is proposing a 3-D similarity enhancement technique useful for improving the segmentation of cardiac structures in Multi-Slice Computerized Tomography (MSCT) volumes. The similarity enhancement is obtained by subtracting the intensity of the current voxel and the gray levels of their adjacent voxels in two volumes resulting after preprocessing. Such volumes are: a. - a volume obtained after applying a Gaussian distribution and a morphological top-hat filter to the input and b. - a smoothed volume generated by processing the input with an average filter. Then, the similarity volume is used as input to a region growing algorithm. This algorithm is applied to extract the shape of cardiac structures, such as left and right ventricles, in MSCT volumes. Qualitative and quantitative results show the good performance of the proposed approach for discrimination of cardiac cavities
Deep Learning from Dual-Energy Information for Whole-Heart Segmentation in Dual-Energy and Single-Energy Non-Contrast-Enhanced Cardiac CT
Deep learning-based whole-heart segmentation in coronary CT angiography
(CCTA) allows the extraction of quantitative imaging measures for
cardiovascular risk prediction. Automatic extraction of these measures in
patients undergoing only non-contrast-enhanced CT (NCCT) scanning would be
valuable. In this work, we leverage information provided by a dual-layer
detector CT scanner to obtain a reference standard in virtual non-contrast
(VNC) CT images mimicking NCCT images, and train a 3D convolutional neural
network (CNN) for the segmentation of VNC as well as NCCT images.
Contrast-enhanced acquisitions on a dual-layer detector CT scanner were
reconstructed into a CCTA and a perfectly aligned VNC image. In each CCTA
image, manual reference segmentations of the left ventricular (LV) myocardium,
LV cavity, right ventricle, left atrium, right atrium, ascending aorta, and
pulmonary artery trunk were obtained and propagated to the corresponding VNC
image. These VNC images and reference segmentations were used to train 3D CNNs
for automatic segmentation in either VNC images or NCCT images. Automatic
segmentations in VNC images showed good agreement with reference segmentations,
with an average Dice similarity coefficient of 0.897 \pm 0.034 and an average
symmetric surface distance of 1.42 \pm 0.45 mm. Volume differences [95%
confidence interval] between automatic NCCT and reference CCTA segmentations
were -19 [-67; 30] mL for LV myocardium, -25 [-78; 29] mL for LV cavity, -29
[-73; 14] mL for right ventricle, -20 [-62; 21] mL for left atrium, and -19
[-73; 34] mL for right atrium, respectively. In 214 (74%) NCCT images from an
independent multi-vendor multi-center set, two observers agreed that the
automatic segmentation was mostly accurate or better. This method might enable
quantification of additional cardiac measures from NCCT images for improved
cardiovascular risk prediction
A Survey on Deep Learning in Medical Image Analysis
Deep learning algorithms, in particular convolutional networks, have rapidly
become a methodology of choice for analyzing medical images. This paper reviews
the major deep learning concepts pertinent to medical image analysis and
summarizes over 300 contributions to the field, most of which appeared in the
last year. We survey the use of deep learning for image classification, object
detection, segmentation, registration, and other tasks and provide concise
overviews of studies per application area. Open challenges and directions for
future research are discussed.Comment: Revised survey includes expanded discussion section and reworked
introductory section on common deep architectures. Added missed papers from
before Feb 1st 201
Vessel tractography using an intensity based tensor model with branch detection
In this paper, we present a tubular structure seg- mentation method that utilizes a second order tensor constructed from directional intensity measurements, which is inspired from diffusion tensor image (DTI) modeling. The constructed anisotropic tensor which is fit inside a vessel drives the segmen- tation analogously to a tractography approach in DTI. Our model is initialized at a single seed point and is capable of capturing whole vessel trees by an automatic branch detection algorithm developed in the same framework. The centerline of the vessel as well as its thickness is extracted. Performance results within the Rotterdam Coronary Artery Algorithm Evaluation framework are provided for comparison with existing techniques. 96.4% average overlap with ground truth delineated by experts is obtained in addition to other measures reported in the paper. Moreover, we demonstrate further quantitative results over synthetic vascular datasets, and we provide quantitative experiments for branch detection on patient Computed Tomography Angiography (CTA) volumes, as well as qualitative evaluations on the same CTA datasets, from visual scores by a cardiologist expert
Faster 3D cardiac CT segmentation with Vision Transformers
Accurate segmentation of the heart is essential for personalized blood flow
simulations and surgical intervention planning. A recent advancement in image
recognition is the Vision Transformer (ViT), which expands the field of view to
encompass a greater portion of the global image context. We adapted ViT for
three-dimensional volume inputs. Cardiac computed tomography (CT) volumes from
39 patients, featuring up to 20 timepoints representing the complete cardiac
cycle, were utilized. Our network incorporates a modified ResNet50 block as
well as a ViT block and employs cascade upsampling with skip connections.
Despite its increased model complexity, our hybrid Transformer-Residual U-Net
framework, termed TRUNet, converges in significantly less time than residual
U-Net while providing comparable or superior segmentations of the left
ventricle, left atrium, left atrial appendage, ascending aorta, and pulmonary
veins. TRUNet offers more precise vessel boundary segmentation and better
captures the heart's overall anatomical structure compared to residual U-Net,
as confirmed by the absence of extraneous clusters of missegmented voxels. In
terms of both performance and training speed, TRUNet exceeded U-Net, a commonly
used segmentation architecture, making it a promising tool for 3D semantic
segmentation tasks in medical imaging. The code for TRUNet is available at
github.com/ljollans/TRUNet
Coronary Artery Segmentation and Motion Modelling
Conventional coronary artery bypass surgery requires invasive sternotomy and the
use of a cardiopulmonary bypass, which leads to long recovery period and has high
infectious potential. Totally endoscopic coronary artery bypass (TECAB) surgery
based on image guided robotic surgical approaches have been developed to allow the
clinicians to conduct the bypass surgery off-pump with only three pin holes incisions
in the chest cavity, through which two robotic arms and one stereo endoscopic camera
are inserted. However, the restricted field of view of the stereo endoscopic images leads
to possible vessel misidentification and coronary artery mis-localization. This results
in 20-30% conversion rates from TECAB surgery to the conventional approach.
We have constructed patient-specific 3D + time coronary artery and left ventricle
motion models from preoperative 4D Computed Tomography Angiography (CTA)
scans. Through temporally and spatially aligning this model with the intraoperative
endoscopic views of the patient's beating heart, this work assists the surgeon to identify
and locate the correct coronaries during the TECAB precedures. Thus this work has
the prospect of reducing the conversion rate from TECAB to conventional coronary
bypass procedures.
This thesis mainly focus on designing segmentation and motion tracking methods
of the coronary arteries in order to build pre-operative patient-specific motion models.
Various vessel centreline extraction and lumen segmentation algorithms are presented,
including intensity based approaches, geometric model matching method and
morphology-based method. A probabilistic atlas of the coronary arteries is formed
from a group of subjects to facilitate the vascular segmentation and registration procedures.
Non-rigid registration framework based on a free-form deformation model
and multi-level multi-channel large deformation diffeomorphic metric mapping are
proposed to track the coronary motion. The methods are applied to 4D CTA images
acquired from various groups of patients and quantitatively evaluated
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