Norberto Malpica

Norberto Malpica
King Juan Carlos University | URJC · Medical Image Analysis and Biometry Lab

PhD

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104
Publications
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Introduction
Skills and Expertise

Publications

Publications (104)
Article
Full-text available
Objective: This study aimed to prove the concept of a new optical video-based system to measure Parkinson's disease (PD) remotely using an accessible standard webcam. Methods: We consecutively enrolled a cohort of 42 patients with PD and healthy subjects (HSs). The participants were recorded performing MDS-UPDRS III bradykinesia upper limb tasks wi...
Article
Full-text available
Medical imaging is considered one of the most important advances in the history of medicine and has become an essential part of the diagnosis and treatment of patients. Earlier prediction and treatment have been driving the acquisition of higher image resolutions as well as the fusion of different modalities, raising the need for sophisticated hard...
Article
Attenuation correction (AC) remains a challenge in pelvis PET/MR imaging. In addition to the segmentation/model-based approaches, deep learning methods have shown promise in synthesizing accurate pelvis attenuation maps (μ-maps). However, these methods often misclassify air pockets in the digestive tract, which can introduce bias in the reconstruct...
Article
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Typically, pseudo-Computerized Tomography (CT) synthesis schemes proposed in the literature rely on complete atlases acquired with the same field of view (FOV) as the input volume. However, clinical CTs are usually acquired in a reduced FOV to decrease patient ionization. In this work, we present the Franken-CT approach, showing how the use of a no...
Article
Collaborative projects allow engineering students to learn from one another and improve the skills necessary for working in a team. We conducted a study in the Spring of 2018 in which 12 Spanish students studying industrial engineering and 12 Indian students studying computer engineering worked together in small teams to solve projects on digital e...
Article
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Open source hardware for scientific equipment needs to provide source files and enough documentation to allow the study, replication and modification of the design. In addition, parametric modeling is encouraged in order to facilitate customization for other experiments. Parametric design using a solid modeling programming language allows customiza...
Article
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Background: Gadolinium-perfusion magnetic resonance (MR) identifies gray matter abnormalities in early multiple sclerosis (MS), even in the absence of structural differences. These perfusion changes could be related to the cognitive disability of these patients, especially in the working memory. Arterial spin labeling (ASL) is a relatively recent...
Article
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Fluorescent cytometry refers to the quantification of cell physical properties and surface biomarkers using fluorescently-tagged antibodies. The generally preferred techniques to perform such measurements are flow cytometry, which performs rapid single cell analysis by flowing cells one-by-one through a channel, and microscopy, which eliminates the...
Article
When a seismometer network records an earthquake, operators will manually review the waveforms and identify the wave phases, a task known as phase picking. Manual phase picking is a time-consuming process that can be automated using machine learning; however, automatic methods have not yet achieved human-level performance, and open-source implement...
Article
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We present a study of multiple sclerosis segmentation algorithms conducted at the international MICCAI 2016 challenge. This challenge was operated using a new open-science computing infrastructure. This allowed for the automatic and independent evaluation of a large range of algorithms in a fair and completely automatic manner. This computing infra...
Article
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Whole-body attenuation correction (AC) is still challenging in combined PET/MR scanners. We describe Dixon-VIBE Deep Learning (DIVIDE), a deep learning network architecture that allows synthesizing pelvis pseudo-CT maps based only on the standard Dixon volumetric interpolated breath-hold examination (Dixon-VIBE) images currently acquired for AC in...
Article
Robust identification and tracking of the pupil provides key information that can be used in several applications such as controlling gaze-based HMIs (human machine interfaces), designing new diagnostic tools for brain diseases, improving driver safety, detecting drowsiness, performing cognitive research, among others. We propose a deep convolution...
Article
Objective: The purpose is to prove that computer-vision techniques allow synthesizing water-fat separation maps for local specific absorption rate (SAR) estimation, when patient-specific water-fat images are not available. Methods: We obtained ground truth head models by using patient-specific water-fat images. We obtained two different label-fu...
Preprint
Full-text available
We present a study of multiple sclerosis segmentation algorithms conducted at the international MICCAI 2016 challenge. This challenge was operated using a new open-science computing infrastructure. This allowed for the automatic and independent evaluation of a large range of algorithms in a fair and completely automatic manner. This computing infra...
Article
Multicolor in situ hybridization (mFISH) is a karyotyping technique used to detect major chromosomal alterations using fluorescent probes and imaging techniques. Manual interpretation of mFISH images is a time consuming step that can be automated using machine learning; in previous works, pixel or patch wise classification was employed, overlooking...
Article
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Fetal health is critically dependent on placental function, especially placental transport of oxygen from mother to fetus. When fetal growth is compromised, placental insufficiency must be distinguished from modest genetic growth potential. If placental insufficiency is present, the physician must trade off the risk of prolonged fetal exposure to p...
Conference Paper
Reconstruction of source neural activity has an increasing importance due to its high time resolution, promoting its application in diagnosis of neurodegenerative and cognitive tasks. To improve the accuracy of reconstruction, we study the influence of anisotropic blood vessels in the EEG-based source localization solution, including several tissue...
Conference Paper
European and Spanish legislation set hourly limits for Nitrogen Dioxide, \(NO_2\), that are enforced with traffic restrictions. In this context it is important to warn the citizens in advance, which can only be done if the \(NO_2\) levels are forecasted. In this paper we propose a deep learning based air quality forecasting system that uses air qua...
Conference Paper
Eyelid identification provides key data that can be used in several application such as controlling gaze-based HMIs (human machine interfaces), the design of new diagnostic tools for brain diseases, improving driver safety, drowsiness detection, research on advertisement, etc. We propose a novel eyetracking algorithm by learning a deep deconvolutio...
Article
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The synthesis of patient data of a certain medical image modality by applying an image processing pipeline starting from other modality is receiving a lot of interest recently, as it allows to save acquisition time and sometimes avoid radiation to the patient. An example of this is the creation of computerized tomography volumes from magnetic reson...
Article
Purpose: To present a method for spatiotemporal alignment of in-utero magnetic resonance imaging (MRI) time series acquired during maternal hyperoxia for enabling improved quantitative tracking of blood oxygen level-dependent (BOLD) signal changes that characterize oxygen transport through the placenta to fetal organs. Materials and methods: The...
Article
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The pathogenesis of orthostatic tremor (OT) remains unclear, although some evidence points to dysfunction in the brainstem or cerebellum. We used single voxel proton magnetic resonance spectroscopy (1H-MRS) (3 T) to investigate whether neurochemical changes underlie abnormal cerebellar or cortical function in OT. Fourteen OT patients and 14 healthy...
Conference Paper
MRI-based bone segmentation is a challenging task because bone tissue and air both present low signal intensity on MR images, making it difficult to accurately delimit the bone boundaries. However, estimating bone from MRI images may allow decreasing patient ionization by removing the need of patient-specific CT acquisition in several applications....
Conference Paper
Full-text available
Magnetic resonance imaging (MRI) is a medical technique used in radiology to obtain anatomical images of healthy and pathological tissues. Due to hardware limitations and clinical protocols, MRI data are often acquired with low-resolution. For this reason, the scientific community has been developing super-resolution (SR) methodologies in order to...
Article
MRI-based bone segmentation is a challenging task because bone tissue and air both present low signal intensity on MR images, making it difficult to accurately delimit the bone boundaries. However, estimating bone from MRI images may allow decreasing patient ionization by removing the need of patient-specific CT acquisition in several applications....
Article
Methods: We propose a fast pseudo-CT generation from a patient-specific MRI T1-weighted image using a group-wise patch-based approach and a MRI-CT atlas dictionary. For every voxel in the input MR image, we compute the similarity of the patch containing that voxel with the patches of all MR images in the database, that lie in a certain anatomical...
Conference Paper
Cardiovascular disease is one of the leading causes of death worldwide. Epicardial adipose tissue (EAT) has emerged as an independent predictor of high cardiometabolic risk. Cardiovascular MRI has proven to be a feasible and reproducible method to assess EAT quantitatively. We present a novel approach for the automated quantification of EAT using "...
Chapter
In each newgeneration of PET scanners, the axial field-of-view(FOV) has been increased as a way to improve their sensitivity and obtain better images, faster and with lower injected doses. Nevertheless, in neurological studies, the use of larger axial FOV can introduce errors in the PET attenuation correction (AC), as possible movements of the pati...
Article
MRI-based skull segmentation is a useful procedure for many imaging applications. This study describes a methodology for automatic segmentation of the complete skull from a single T1-weighted volume. The skull is estimated using a multi-atlas segmentation approach. Using a whole head computed tomography (CT) scan database, the skull in a new MRI vo...
Conference Paper
In recent years, medical images have been increasingly used as an objective method for the diagnosis of neurodegenerative diseases. Most previous studies have been based on structural or functional magnetic resonance imaging. However, the results are not yet sufficient to identify early stages of dementia. In this paper, we present an image process...
Article
PurposeSpecific absorption rate (SAR) amplification around active implantable medical devices during diagnostic MRI procedures poses a potential risk for patient safety. In this study, we present a parallel transmit (pTx) strategy that can be used to safely scan patients with deep brain stimulation (DBS) implants.Methods We performed electromagneti...
Article
PurposeLocal specific absorption rate (SAR) limits many applications of parallel transmit (pTx) in ultra high-field imaging. In this Note, we introduce the use of an array element, which is intentionally inefficient at generating spin excitation (a “dark mode”) to attempt a partial cancellation of the electric field from those elements that do gene...
Conference Paper
Rectal cancer (RC) is associated with a poor prognosis because of the risk both for metastases and for local recurrence after total mesorectal excision (TME) surgery. Preoperative assessment (cTNM) for neoadjuvant therapy (radiation therapy and/or chemotherapy) is very important to minimize recurrence rates. Therefore, the challenge for preoperativ...
Article
The Multiclinical Trial Web PACS (MCTWP) is a free software platform to support image management in clinical trials. This means not only long-term image storage, but also trial protocol support, post-processing, task management and result registration. The application makes it possible to ensure traceability and replicability in experiments and mea...
Conference Paper
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Complex pathological brain patterns generally are found in neurodegenerative diseases which can be correlated with different clinical onsets of a particular pathology. Currently, an objective method that aids to determine such signs, in terms of global and local changes, is not available in clinical practice and the whole interpretation is dependen...
Article
In this paper we propose some new box relaxation numerical schemes on staggered grids to solve the stationary system of partial differential equations arising from the dual minimization problem associated to the Total Variation operator. We present in detail the numerical schemes for the scalar case and its generalization to multichannel (vectorial...
Article
Resolution in Magnetic Resonance (MR) is limited by diverse physical, technological and economical considerations. In conventional medical practice, resolution enhancement is usually performed with bicubic or B-spline interpolations, strongly affecting the accuracy of subsequent processing steps such as segmentation or registration. This paper pres...
Article
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This paper presents an automatic approach which classifies structural Magnetic Resonance images into pathological or healthy controls. A classification model was trained to find the boundaries that allow to separate the study groups. The method uses the deformation values from a set of regions, automatically identified as relevant, in a process tha...
Article
Impairment of the olfactory sensibility can be an indicator of neurode generative disorders, such as Alzheimer's disease and Parkinson's disease. The problem lies in obtaining an objective quantitative analysis of olfactory response. For this task, we will use functional magnetic resonance imaging (fMRI) and a device that will provide a selective a...
Conference Paper
Full-text available
Quantitative analysis on diffusion tensor imaging (DTI) has shown be useful in the study of disease-related degeneration. More and more studies perform voxel-by-voxel comparisons of fractional anisotropy (FA) values, aiming at detecting white matter alterations. Overall, there is no agreement about how the normalization stage should be performed....
Conference Paper
Full-text available
This paper describes the Electronics curriculum in the Telecommunication Engineer degree at Rey Juan Carlos University (URJC) in Spain. Telecommunication Engineering started in the 2003-2004 academic year. In these years, all the electronic courses have been set up with a main practical orientation and with Project Based Learning (PBL) activities,...
Conference Paper
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The measure of leaf damage is a basic tool in plant epidemiology research. Measuring the area of a great number of leaves is subjective and time consuming. We investigate the use of machine learning approaches for the objective segmentation and quantification of leaf area damaged by mites in avocado leaves. After extraction of the leaf veins, pixel...
Conference Paper
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In this paper we present our experience in teaching digital electronic circuit and system design with FPGAs using VHDL. The course follows a project based learning methodology, in which the students learn how to design digital circuits and systems in a practical way. During the course, students design electronic circuits of incremental complexity....
Conference Paper
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In this work, a device for generating automated olfactory stimuli in functional magnetic resonance imaging (fMRI) studies is described. The novel issues of our design are: synchronization between the acquisition and the olfactory task, automated control of experimental parameters (odorants sequences, frequency, time and concentration of stimuli). F...
Conference Paper
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Digital (binary) image segmentation is a critical step in most image processing protocols, especially in medical imaging where accurate and fast segmentation and classification are a challenging issue. In this paper we present a fast relaxation algorithm to minimize an anistropic Mumford-Shah energy functional for piecewise constant approximation o...
Article
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Variational methods for region classification have shown very promising results in medical image analysis. The Chan‐Vese model is one of the most popular methods, but its numerical resolution is slow and it has serious drawbacks for most multiphase applications. In this work, we extend the link, stablished by Chambolle, between the two classes bin...
Article
The evaluation of new therapies to treat allergic asthma makes frequent use of histological studies. Some of them are based on microscope observation of stained paraffin lung sections to quantify cellular infiltrate, an effect directly related to allergic processes. Currently, there is no software tool available for doing this quantification automa...
Article
Full-text available
In this work, a device for generating automated olfactory stimuli in functional magnetic resonance imaging (fMRI) studies is described. The novel issues of our design are: synchronization between the acquisition and the olfactory task, automated control of experimental parameters (odorants sequences, frequency, time and concentration of stimuli). F...
Conference Paper
Full-text available
Liver volumetry is a required step for the planning of liver surgery and resection. It is generally based on Computerized tomography images, and segmentation of the liver is the most important step of the process. We propose an automatic segmentation algorithm based on a geometric level set method which provides an accurate segmentation of the liv...
Article
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Medical information systems are not designed for clinical trials using clinical imaging. This paper presents a conceptual model for clinical trials based on medical imaging from two complementary points of view: a technical model and a business model. A Web information system (WIS) for supporting multicenter clinical trials has been designed to imp...
Article
Medical information systems are not designed for clinical trials using clinical imaging. This paper presents a conceptual model for clinical trials based on medical imaging from two complementary points of view: a technical model and a business model. A Web information system (WIS) for supporting multicen-ter clinical trials has been designed to im...
Conference Paper
The importance of the transition matrix has been recently pointed out by several research groups in 3D Positron Emission Tomography (PET) reconstruction. Analytical methods have become an alternative to Monte Carlo Simulations. In order to reduce the storage of this huge matrix and to make some calculations feasible it is possible to factorize this...
Conference Paper
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Myocardial Contrast Echocardiography (MCE) is a recent technique that allows to measure regional perfusion in the cardiac wall. Segmentation of MCE sequences would allow simultaneous evaluation of perfusion and wall motion. This paper deals with the application of partial differential equations (PDE) for tracking the endocardial wall. We use a vari...
Conference Paper
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This paper presents a new fool developed to quantify and characterize blood flow in great vessels. The aim is to quantify the flow during the cardiac cycle from sequences of magnetic resonance images of the vessel cross-section. The proposed method tracks the vessel contour to automatically quantify the maximum velocity and flow through the cardiac...
Article
The aim of this study is to analyse spatial distribution of myocardial velocities (MV) and myocardial velocity gradient (MVG) with color M-mode Doppler tissue imaging (DTI) and to analyse the influence of age in such parameters. A prospective study including 66 healthy volunteers was carried out with color M-mode DTI. Postprocessing of images was p...
Conference Paper
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The main goal of this work was to implement an easy and convenient new tool to load, visualize and segment cardiac magnetic resonance images (CMRI) in order to obtain basic parameters for cardiac function estimation and to visualize the results in a quantitative and graphical way. The proposed method tracks the contour of the left ventricle at endo...
Conference Paper
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This paper proposes a new method to compute the 2D strain tensor from gray-scale 2D echocardiographic sequences and presents a clinical trial to test its applicability to regional analysis of the left ventricle. Myocardial motion is computed using spatio-temporal nonrigid registration techniques on the whole sequence. The key feature of our method...
Article
Analysis of intramyocardial perfusion by contrast echocardiography provides quantitative parameters for the assessment of ischemic disease. This analysis can be achieved by applying an ultrasound (US) burst of high mechanical index to destroy contrast bubbles, measuring various myocardial refilling parameters from the time curves obtained from regi...
Article
Contrast echocardiography has been proposed as an indicator of myocardial perfusion in a non-invasive way. Reperfusion curves can be obtained by destroying all the microbubbles using an ultrasound pulse with high mechanical index and acquiring images during the reperfusion process. Quantitative parameters describing the process can be obtained from...
Article
Introduction: The endoepicardial ratio of myocardial blood flow is highly sensitive to ischemia. This study investigates myocardial perfusion in the endo- and epicardium, using contrast echocardiography (CE), and analyzes the correlation of different recorded parameters to a gold standard represented by colorimetric microspheres (MS). Methods: Real...