12 research outputs found
Left Ventricle Quantification Using Direct Regression with Segmentation Regularization and Ensembles of Pretrained 2D and 3D CNNs
Cardiac left ventricle (LV) quantification provides a tool for diagnosing
cardiac diseases. Automatic calculation of all relevant LV indices from cardiac
MR images is an intricate task due to large variations among patients and
deformation during the cardiac cycle. Typical methods are based on segmentation
of the myocardium or direct regression from MR images. To consider cardiac
motion and deformation, recurrent neural networks and spatio-temporal
convolutional neural networks (CNNs) have been proposed. We study an approach
combining state-of-the-art models and emphasizing transfer learning to account
for the small dataset provided for the LVQuan19 challenge. We compare 2D
spatial and 3D spatio-temporal CNNs for LV indices regression and cardiac phase
classification. To incorporate segmentation information, we propose an
architecture-independent segmentation-based regularization. To improve the
robustness further, we employ a search scheme that identifies the optimal
ensemble from a set of architecture variants. Evaluating on the LVQuan19
Challenge training dataset with 5-fold cross-validation, we achieve mean
absolute errors of 111 +- 76mm^2, 1.84 +- 0.9mm and 1.22 +- 0.6mm for area,
dimension and regional wall thickness regression, respectively. The error rate
for cardiac phase classification is 6.7%.Comment: Accepted at the MICCAI Workshop STACOM 201
Leveraging Disease Progression Learning for Medical Image Recognition
Unlike natural images, medical images often have intrinsic characteristics
that can be leveraged for neural network learning. For example, images that
belong to different stages of a disease may continuously follow a certain
progression pattern. In this paper, we propose a novel method that leverages
disease progression learning for medical image recognition. In our method,
sequences of images ordered by disease stages are learned by a neural network
that consists of a shared vision model for feature extraction and a long
short-term memory network for the learning of stage sequences. Auxiliary vision
outputs are also included to capture stage features that tend to be discrete
along the disease progression. Our proposed method is evaluated on a public
diabetic retinopathy dataset, and achieves about 3.3% improvement in disease
staging accuracy, compared to the baseline method that does not use disease
progression learning
Recurrent Neural Networks for Aortic Image Sequence Segmentation with Sparse Annotations
Segmentation of image sequences is an important task in medical image analysis, which enables clinicians to assess the anatomy and function of moving organs. However, direct application of a segmentation algorithm to each time frame of a sequence may ignore the temporal continuity inherent in the sequence. In this work, we propose an image sequence segmentation algorithm by combining a fully convolutional network with a recurrent neural network, which incorporates both spatial and temporal information into the segmentation task. A key challenge in training this network is that the available manual annotations are temporally sparse, which forbids end-to-end training. We address this challenge by performing non-rigid label propagation on the annotations and introducing an exponentially weighted loss function for training. Experiments on aortic MR image sequences demonstrate that the proposed method significantly improves both accuracy and temporal smoothness of segmentation, compared to a baseline method that utilises spatial information only. It achieves an average Dice metric of 0.960 for the ascending aorta and 0.953 for the descending aorta