114 research outputs found
Stima del movimento nella sintesi di immagini panoramiche in tempo reale su piattaforma DSP
La problematica centrale per la ricostruzione di immagini panoramiche da una sequenza video è la stima del movimento tra coppie di fotogrammi.
Dopo un'analisi degli stimatori di moto noti in letteratura è stato proposto e caratterizzato un nuovo operatore di stima del movimento, le cui prestazioni sono state confrontate con algoritmi noti.
Un algoritmo di stima del moto basato sul nuovo operatore è stato poi implementato su un sistema di elaborazione video in tempo reale: l'MVE I
HoVer-UNet: Accelerating HoVerNet with UNet-based multi-class nuclei segmentation via knowledge distillation
We present HoVer-UNet, an approach to distill the knowledge of the
multi-branch HoVerNet framework for nuclei instance segmentation and
classification in histopathology. We propose a compact, streamlined single UNet
network with a Mix Vision Transformer backbone, and equip it with a custom loss
function to optimally encode the distilled knowledge of HoVerNet, reducing
computational requirements without compromising performances. We show that our
model achieved results comparable to HoVerNet on the public PanNuke and Consep
datasets with a three-fold reduction in inference time. We make the code of our
model publicly available at https://github.com/DIAGNijmegen/HoVer-UNet.Comment: 4 pages, 2 figures, submitted to ISBI 202
Quantifying the effects of data augmentation and stain color normalization in convolutional neural networks for computational pathology
Stain variation is a phenomenon observed when distinct pathology laboratories
stain tissue slides that exhibit similar but not identical color appearance.
Due to this color shift between laboratories, convolutional neural networks
(CNNs) trained with images from one lab often underperform on unseen images
from the other lab. Several techniques have been proposed to reduce the
generalization error, mainly grouped into two categories: stain color
augmentation and stain color normalization. The former simulates a wide variety
of realistic stain variations during training, producing stain-invariant CNNs.
The latter aims to match training and test color distributions in order to
reduce stain variation. For the first time, we compared some of these
techniques and quantified their effect on CNN classification performance using
a heterogeneous dataset of hematoxylin and eosin histopathology images from 4
organs and 9 pathology laboratories. Additionally, we propose a novel
unsupervised method to perform stain color normalization using a neural
network. Based on our experimental results, we provide practical guidelines on
how to use stain color augmentation and stain color normalization in future
computational pathology applications.Comment: Accepted in the Medical Image Analysis journa
HookNet: multi-resolution convolutional neural networks for semantic segmentation in histopathology whole-slide images
We propose HookNet, a semantic segmentation model for histopathology
whole-slide images, which combines context and details via multiple branches of
encoder-decoder convolutional neural networks. Concentricpatches at multiple
resolutions with different fields of view are used to feed different branches
of HookNet, and intermediate representations are combined via a hooking
mechanism. We describe a framework to design and train HookNet for achieving
high-resolution semantic segmentation and introduce constraints to guarantee
pixel-wise alignment in feature maps during hooking. We show the advantages of
using HookNet in two histopathology image segmentation tasks where tissue type
prediction accuracy strongly depends on contextual information, namely (1)
multi-class tissue segmentation in breast cancer and, (2) segmentation of
tertiary lymphoid structures and germinal centers in lung cancer. Weshow the
superiority of HookNet when compared with single-resolution U-Net models
working at different resolutions as well as with a recently published
multi-resolution model for histopathology image segmentatio
Assessment Of Intra-coronary Stent Location And Extension In Intravascular Ultrasound Sequences.
Purpose An intraluminal coronary stent is a metal scaffold deployed in a stenotic artery during percutaneous coronary intervention (PCI). In order to have an effective deployment, a stent should be optimally placed with regard to anatomical structures such as bifurcations and stenoses. Intravascular ultrasound (IVUS) is a catheter-based imaging technique generally used for PCI guiding and assessing the correct placement of the stent. A novel approach that automatically detects the boundaries and the position of the stent along the IVUS pullback is presented. Such a technique aims at optimizing the stent deployment. Methods The method requires the identification of the stable frames of the sequence and the reliable detection of stent struts. Using these data, a measure of likelihood for a frame to contain a stent is computed. Then, a robust binary representation of the presence of the stent in the pullback is obtained applying an iterative and multiscale quantization of the signal to symbols using the Symbolic Aggregate approXimation algorithm. Results The technique was extensively validated on a set of 103 IVUS of sequences of in vivo coronary arteries containing metallic and bioabsorbable stents acquired through an international multicentric collaboration across five clinical centers. The method was able to detect the stent position with an overall F-measure of 86.4%, a Jaccard index score of 75% and a mean distance of 2.5 mm from manually annotated stent boundaries, and in bioabsorbable stents with an overall F-measure of 88.6%, a Jaccard score of 77.7 and a mean distance of 1.5 mm from manually annotated stent boundaries. Additionally, a map indicating the distance between the lumen and the stent along the pullback is created in order to show the angular sectors of the sequence in which the malapposition is present. Conclusions Results obtained comparing the automatic results vs the manual annotation of two observers shows that the method approaches the interobserver variability. Similar performances are obtained on both metallic and bioabsorbable stents, showing the flexibility and robustness of the method
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
Towards automatic pulmonary nodule management in lung cancer screening with deep learning
The introduction of lung cancer screening programs will produce an
unprecedented amount of chest CT scans in the near future, which radiologists
will have to read in order to decide on a patient follow-up strategy. According
to the current guidelines, the workup of screen-detected nodules strongly
relies on nodule size and nodule type. In this paper, we present a deep
learning system based on multi-stream multi-scale convolutional networks, which
automatically classifies all nodule types relevant for nodule workup. The
system processes raw CT data containing a nodule without the need for any
additional information such as nodule segmentation or nodule size and learns a
representation of 3D data by analyzing an arbitrary number of 2D views of a
given nodule. The deep learning system was trained with data from the Italian
MILD screening trial and validated on an independent set of data from the
Danish DLCST screening trial. We analyze the advantage of processing nodules at
multiple scales with a multi-stream convolutional network architecture, and we
show that the proposed deep learning system achieves performance at classifying
nodule type that surpasses the one of classical machine learning approaches and
is within the inter-observer variability among four experienced human
observers.Comment: Published on Scientific Report
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