17 research outputs found
Semi-supervised assessment of incomplete LV coverage in cardiac MRI using generative adversarial nets
Cardiac magnetic resonance (CMR) images play a growing role in diagnostic imaging of cardiovascular diseases. Ensuring full coverage of the Left Ventricle (LV) is a basic criteria of CMR image quality. Complete LV coverage, from base to apex, precedes accurate cardiac volume and functional assessment. Incomplete coverage of the LV is identified through visual inspection, which is time-consuming and usually done retrospectively in large imaging cohorts. In this paper, we propose a novel semi-supervised method to check the coverage of LV from CMR images by using generative adversarial networks (GAN), we call it Semi-Coupled-GANs (SCGANs). To identify missing basal and apical slices in a CMR volume, a two-stage framework is proposed. First, the SCGANs generate adversarial examples and extract high-level features from the CMR images; then these image attributes are used to detect missing basal and apical slices. We constructed extensive experiments to validate the proposed method on UK Biobank with more than 6000 independent volumetric MR scans, which achieved high accuracy and robust results for missing slice detection, comparable with those of state of the art deep learning methods. The proposed method, in principle, can be adapted to other CMR image data for LV coverage assessment
Enhanced Magnetic Resonance Image Synthesis with Contrast-Aware Generative Adversarial Networks
A Magnetic Resonance Imaging (MRI) exam typically consists of the acquisition
of multiple MR pulse sequences, which are required for a reliable diagnosis.
Each sequence can be parameterized through multiple acquisition parameters
affecting MR image contrast, signal-to-noise ratio, resolution, or scan time.
With the rise of generative deep learning models, approaches for the synthesis
of MR images are developed to either synthesize additional MR contrasts,
generate synthetic data, or augment existing data for AI training. However,
current generative approaches for the synthesis of MR images are only trained
on images with a specific set of acquisition parameter values, limiting the
clinical value of these methods as various sets of acquisition parameter
settings are used in clinical practice. Therefore, we trained a generative
adversarial network (GAN) to generate synthetic MR knee images conditioned on
various acquisition parameters (repetition time, echo time, image orientation).
This approach enables us to synthesize MR images with adjustable image
contrast. In a visual Turing test, two experts mislabeled 40.5% of real and
synthetic MR images, demonstrating that the image quality of the generated
synthetic and real MR images is comparable. This work can support radiologists
and technologists during the parameterization of MR sequences by previewing the
yielded MR contrast, can serve as a valuable tool for radiology training, and
can be used for customized data generation to support AI training
Deep Learning using K-space Based Data Augmentation for Automated Cardiac MR Motion Artefact Detection
Quality assessment of medical images is essential for complete automation of
image processing pipelines. For large population studies such as the UK
Biobank, artefacts such as those caused by heart motion are problematic and
manual identification is tedious and time-consuming. Therefore, there is an
urgent need for automatic image quality assessment techniques. In this paper,
we propose a method to automatically detect the presence of motion-related
artefacts in cardiac magnetic resonance (CMR) images. As this is a highly
imbalanced classification problem (due to the high number of good quality
images compared to the low number of images with motion artefacts), we propose
a novel k-space based training data augmentation approach in order to address
this problem. Our method is based on 3D spatio-temporal Convolutional Neural
Networks, and is able to detect 2D+time short axis images with motion artefacts
in less than 1ms. We test our algorithm on a subset of the UK Biobank dataset
consisting of 3465 CMR images and achieve not only high accuracy in detection
of motion artefacts, but also high precision and recall. We compare our
approach to a range of state-of-the-art quality assessment methods.Comment: Accepted for MICCAI2018 Conferenc
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Large-scale Quality Control of Cardiac Imaging in Population Studies: Application to UK Biobank
In large population studies such as the UK Biobank (UKBB), quality control of the acquired images by visual assessment is unfeasible. In this paper, we apply a recently developed fully-automated quality control pipeline for cardiac MR (CMR) images to the first 19,265 short-axis (SA) cine stacks from the UKBB. We present the results for the three estimated quality metrics (heart coverage, inter-slice motion and image contrast in the cardiac region) as well as their potential associations with factors including acquisition details and subject-related phenotypes. Up to 14.2% of the analysed SA stacks had sub-optimal coverage (i.e. missing basal and/or apical slices), however most of them were limited to the first year of acquisition. Up to 16% of the stacks were affected by noticeable inter-slice motion (i.e. average inter-slice misalignment greater than 3.4 mm). Inter-slice motion was positively correlated with weight and body surface area. Only 2.1% of the stacks had an average end-diastolic cardiac image contrast below 30% of the dynamic range. These findings will be highly valuable for both the scientists involved in UKBB CMR acquisition and for the ones who use the dataset for research purposes
A Generalised Deep Meta-Learning Model for Automated Quality Control of Cardiovascular Magnetic Resonance Images
Background and Objectives: Cardiovascular magnetic resonance (CMR) imaging is
a powerful modality in functional and anatomical assessment for various
cardiovascular diseases. Sufficient image quality is essential to achieve
proper diagnosis and treatment. A large number of medical images, the variety
of imaging artefacts, and the workload of imaging centres are among the things
that reveal the necessity of automatic image quality assessment (IQA). However,
automated IQA requires access to bulk annotated datasets for training deep
learning (DL) models. Labelling medical images is a tedious, costly and
time-consuming process, which creates a fundamental challenge in proposing
DL-based methods for medical applications. This study aims to present a new
method for CMR IQA when there is limited access to annotated datasets. Methods:
The proposed generalised deep meta-learning model can evaluate the quality by
learning tasks in the prior stage and then fine-tuning the resulting model on a
small labelled dataset of the desired tasks. This model was evaluated on the
data of over 6,000 subjects from the UK Biobank for five defined tasks,
including detecting respiratory motion, cardiac motion, Aliasing and Gibbs
ringing artefacts and images without artefacts. Results: The results of
extensive experiments show the superiority of the proposed model. Besides,
comparing the model's accuracy with the domain adaptation model indicates a
significant difference by using only 64 annotated images related to the desired
tasks. Conclusion: The proposed model can identify unknown artefacts in images
with acceptable accuracy, which makes it suitable for medical applications and
quality assessment of large cohorts.Comment: 16 pages, 1 figure, 2 table