15 research outputs found
Adversarial Inpainting of Medical Image Modalities
Numerous factors could lead to partial deteriorations of medical images. For
example, metallic implants will lead to localized perturbations in MRI scans.
This will affect further post-processing tasks such as attenuation correction
in PET/MRI or radiation therapy planning. In this work, we propose the
inpainting of medical images via Generative Adversarial Networks (GANs). The
proposed framework incorporates two patch-based discriminator networks with
additional style and perceptual losses for the inpainting of missing
information in realistically detailed and contextually consistent manner. The
proposed framework outperformed other natural image inpainting techniques both
qualitatively and quantitatively on two different medical modalities.Comment: To be submitted to ICASSP 201
Retrospective correction of Rigid and Non-Rigid MR motion artifacts using GANs
Motion artifacts are a primary source of magnetic resonance (MR) image
quality deterioration with strong repercussions on diagnostic performance.
Currently, MR motion correction is carried out either prospectively, with the
help of motion tracking systems, or retrospectively by mainly utilizing
computationally expensive iterative algorithms. In this paper, we utilize a new
adversarial framework, titled MedGAN, for the joint retrospective correction of
rigid and non-rigid motion artifacts in different body regions and without the
need for a reference image. MedGAN utilizes a unique combination of
non-adversarial losses and a new generator architecture to capture the textures
and fine-detailed structures of the desired artifact-free MR images.
Quantitative and qualitative comparisons with other adversarial techniques have
illustrated the proposed model performance.Comment: 5 pages, 2 figures, under review for the IEEE International Symposium
for Biomedical Image
AeGAN: Time-Frequency Speech Denoising via Generative Adversarial Networks
Automatic speech recognition (ASR) systems are of vital importance nowadays
in commonplace tasks such as speech-to-text processing and language
translation. This created the need for an ASR system that can operate in
realistic crowded environments. Thus, speech enhancement is a valuable building
block in ASR systems and other applications such as hearing aids, smartphones
and teleconferencing systems. In this paper, a generative adversarial network
(GAN) based framework is investigated for the task of speech enhancement, more
specifically speech denoising of audio tracks. A new architecture based on
CasNet generator and an additional feature-based loss are incorporated to get
realistically denoised speech phonetics. Finally, the proposed framework is
shown to outperform other learning and traditional model-based speech
enhancement approaches.Comment: 5 pages, 4 figures and 2 Tables. Accepted in EUSIPCO 202
MedGAN: Medical Image Translation using GANs
Image-to-image translation is considered a new frontier in the field of
medical image analysis, with numerous potential applications. However, a large
portion of recent approaches offers individualized solutions based on
specialized task-specific architectures or require refinement through
non-end-to-end training. In this paper, we propose a new framework, named
MedGAN, for medical image-to-image translation which operates on the image
level in an end-to-end manner. MedGAN builds upon recent advances in the field
of generative adversarial networks (GANs) by merging the adversarial framework
with a new combination of non-adversarial losses. We utilize a discriminator
network as a trainable feature extractor which penalizes the discrepancy
between the translated medical images and the desired modalities. Moreover,
style-transfer losses are utilized to match the textures and fine-structures of
the desired target images to the translated images. Additionally, we present a
new generator architecture, titled CasNet, which enhances the sharpness of the
translated medical outputs through progressive refinement via encoder-decoder
pairs. Without any application-specific modifications, we apply MedGAN on three
different tasks: PET-CT translation, correction of MR motion artefacts and PET
image denoising. Perceptual analysis by radiologists and quantitative
evaluations illustrate that the MedGAN outperforms other existing translation
approaches.Comment: 16 pages, 8 figure
Person Identification and Body Mass Index: A Deep Learning-Based Study on Micro-Dopplers
Obtaining a smart surveillance requires a sensing system that can capture
accurate and detailed information for the human walking style. The radar
micro-Doppler (-D) analysis is proved to be a reliable metric
for studying human locomotions. Thus, -D signatures can be
used to identify humans based on their walking styles. Additionally, the
signatures contain information about the radar cross section (RCS) of the
moving subject. This paper investigates the effect of human body
characteristics on human identification based on their -D
signatures. In our proposed experimental setup, a treadmill is used to collect
-D signatures of 22 subjects with different genders and body
characteristics. Convolutional autoencoders (CAE) are then used to extract the
latent space representation from the -D signatures. It is
then interpreted in two dimensions using t-distributed stochastic neighbor
embedding (t-SNE). Our study shows that the body mass index (BMI) has a
correlation with the -D signature of the walking subject. A
50-layer deep residual network is then trained to identify the walking subject
based on the -D signature. We achieve an accuracy of 98% on
the test set with high signal-to-noise-ratio (SNR) and 84% in case of different
SNR levels.Comment: Accepted in IEEE Radarconf1
ipA-MedGAN: Inpainting of Arbitrary Regions in Medical Imaging
Local deformations in medical modalities are common phenomena due to a
multitude of factors such as metallic implants or limited field of views in
magnetic resonance imaging (MRI). Completion of the missing or distorted
regions is of special interest for automatic image analysis frameworks to
enhance post-processing tasks such as segmentation or classification. In this
work, we propose a new generative framework for medical image inpainting,
titled ipA-MedGAN. It bypasses the limitations of previous frameworks by
enabling inpainting of arbitrary shaped regions without a prior localization of
the regions of interest. Thorough qualitative and quantitative comparisons with
other inpainting and translational approaches have illustrated the superior
performance of the proposed framework for the task of brain MR inpainting.Comment: Submitted to IEEE ICIP 202
The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance
INTRODUCTION
Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic.
RATIONALE
We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs).
RESULTS
Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants.
CONCLUSION
Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century
Wavelet-based Unsupervised Label-to-Image Translation
Semantic Image Synthesis (SIS) is a subclass of image-to-image translation
where a semantic layout is used to generate a photorealistic image.
State-of-the-art conditional Generative Adversarial Networks (GANs) need a huge
amount of paired data to accomplish this task while generic unpaired
image-to-image translation frameworks underperform in comparison, because they
color-code semantic layouts and learn correspondences in appearance instead of
semantic content. Starting from the assumption that a high quality generated
image should be segmented back to its semantic layout, we propose a new
Unsupervised paradigm for SIS (USIS) that makes use of a self-supervised
segmentation loss and whole image wavelet based discrimination. Furthermore, in
order to match the high-frequency distribution of real images, a novel
generator architecture in the wavelet domain is proposed. We test our
methodology on 3 challenging datasets and demonstrate its ability to bridge the
performance gap between paired and unpaired models.Comment: arXiv admin note: substantial text overlap with arXiv:2109.1471