8 research outputs found
On Improving Generalization of CNN-Based Image Classification with Delineation Maps Using the CORF Push-Pull Inhibition Operator
Deployed image classification pipelines are typically dependent on the images captured in real-world environments. This means that images might be affected by different sources of perturbations (e.g. sensor noise in low-light environments). The main challenge arises by the fact that image quality directly impacts the reliability and consistency of classification tasks. This challenge has, hence, attracted wide interest within the computer vision communities. We propose a transformation step that attempts to enhance the generalization ability of CNN models in the presence of unseen noise in the test set. Concretely, the delineation maps of given images are determined using the CORF push-pull inhibition operator. Such an operation transforms an input image into a space that is more robust to noise before being processed by a CNN. We evaluated our approach on the Fashion MNIST data set with an AlexNet model. It turned out that the proposed CORF-augmented pipeline achieved comparable results on noise-free images to those of a conventional AlexNet classification model without CORF delineation maps, but it consistently achieved significantly superior performance on test images perturbed with different levels of Gaussian and uniform noise
Topology-preserving augmentation for cnn-based segmentation of congenital heart defects from 3d paediatric cmr
Patient-specific 3D printing of congenital heart anatomy demands an accurate
segmentation of the thin tissue interfaces which characterise these diagnoses.
Even when a label set has a high spatial overlap with the ground truth,
inaccurate delineation of these interfaces can result in topological errors.
These compromise the clinical utility of such models due to the anomalous
appearance of defects. CNNs have achieved state-of-the-art performance in
segmentation tasks. Whilst data augmentation has often played an important
role, we show that conventional image resampling schemes used therein can
introduce topological changes in the ground truth labelling of augmented
samples. We present a novel pipeline to correct for these changes, using a
fast-marching algorithm to enforce the topology of the ground truth labels
within their augmented representations. In so doing, we invoke the idea of
cardiac contiguous topology to describe an arbitrary combination of congenital
heart defects and develop an associated, clinically meaningful metric to
measure the topological correctness of segmentations. In a series of five-fold
cross-validations, we demonstrate the performance gain produced by this
pipeline and the relevance of topological considerations to the segmentation of
congenital heart defects. We speculate as to the applicability of this approach
to any segmentation task involving morphologically complex targets.Comment: To be published at MICCAI PIPPI 201
Smoking and Second Hand Smoking in Adolescents with Chronic Kidney Disease: A Report from the Chronic Kidney Disease in Children (CKiD) Cohort Study
The goal of this study was to determine the prevalence of smoking and second hand smoking [SHS] in adolescents with CKD and their relationship to baseline parameters at enrollment in the CKiD, observational cohort study of 600 children (aged 1-16 yrs) with Schwartz estimated GFR of 30-90 ml/min/1.73m2. 239 adolescents had self-report survey data on smoking and SHS exposure: 21 [9%] subjects had “ever” smoked a cigarette. Among them, 4 were current and 17 were former smokers. Hypertension was more prevalent in those that had “ever” smoked a cigarette (42%) compared to non-smokers (9%), p\u3c0.01. Among 218 non-smokers, 130 (59%) were male, 142 (65%) were Caucasian; 60 (28%) reported SHS exposure compared to 158 (72%) with no exposure. Non-smoker adolescents with SHS exposure were compared to those without SHS exposure. There was no racial, age, or gender differences between both groups. Baseline creatinine, diastolic hypertension, C reactive protein, lipid profile, GFR and hemoglobin were not statistically different. Significantly higher protein to creatinine ratio (0.90 vs. 0.53, p\u3c0.01) was observed in those exposed to SHS compared to those not exposed. Exposed adolescents were heavier than non-exposed adolescents (85th percentile vs. 55th percentile for BMI, p\u3c 0.01). Uncontrolled casual systolic hypertension was twice as prevalent among those exposed to SHS (16%) compared to those not exposed to SHS (7%), though the difference was not statistically significant (p= 0.07). Adjusted multivariate regression analysis [OR (95% CI)] showed that increased protein to creatinine ratio [1.34 (1.03, 1.75)] and higher BMI [1.14 (1.02, 1.29)] were independently associated with exposure to SHS among non-smoker adolescents. These results reveal that among adolescents with CKD, cigarette use is low and SHS is highly prevalent. The association of smoking with hypertension and SHS with increased proteinuria suggests a possible role of these factors in CKD progression and cardiovascular outcomes
Ultrasensitive detection of toxocara canis excretory-secretory antigens by a nanobody electrochemical magnetosensor assay.
peer reviewedHuman Toxocariasis (HT) is a zoonotic disease caused by the migration
of the larval stage of the roundworm Toxocara canis in the human host.
Despite of being the most cosmopolitan helminthiasis worldwide, its
diagnosis is elusive. Currently, the detection of specific immunoglobulins
IgG against the Toxocara Excretory-Secretory Antigens (TES), combined
with clinical and epidemiological criteria is the only strategy to diagnose
HT. Cross-reactivity with other parasites and the inability to distinguish
between past and active infections are the main limitations of this
approach. Here, we present a sensitive and specific novel strategy to
detect and quantify TES, aiming to identify active cases of HT. High
specificity is achieved by making use of nanobodies (Nbs), recombinant
single variable domain antibodies obtained from camelids, that due to
their small molecular size (15kDa) can recognize hidden epitopes not
accessible to conventional antibodies. High sensitivity is attained by the
design of an electrochemical magnetosensor with an amperometric readout
with all components of the assay mixed in one single step. Through
this strategy, 10-fold higher sensitivity than a conventional sandwich
ELISA was achieved. The assay reached a limit of detection of 2 and15
pg/ml in PBST20 0.05% or serum, spiked with TES, respectively. These
limits of detection are sufficient to detect clinically relevant toxocaral
infections. Furthermore, our nanobodies showed no cross-reactivity
with antigens from Ascaris lumbricoides or Ascaris suum. This is to our
knowledge, the most sensitive method to detect and quantify TES so far,
and has great potential to significantly improve diagnosis of HT. Moreover,
the characteristics of our electrochemical assay are promising for the
development of point of care diagnostic systems using nanobodies as a
versatile and innovative alternative to antibodies. The next step will be the
validation of the assay in clinical and epidemiological contexts