Juan F P J Abascal

Spectral photon-counting computed tomography (SPCCT) is a new technique with the capability to provide mono-energetic (monoE) images with high signal to noise ratio. We demonstrate the feasibility of SPCCT to characterize at the same time cartilage and subchondral bone cysts (SBCs) without contrast agent in osteoarthritis (OA). To achieve this goal...

Spectral Photon-Counting Computed Tomography (SPCCT) is a new technique with the capability to provide mono-energetic (monoE) images with high signal to noise ratio. We demonstrate the feasibility of SPCCT to characterize at the same time cartilage and subchondral bone cysts (SBCs) without contrast agent in osteoarthritis (OA). To achieve this goal...

Single-pixel imaging acquires an image by measuring its coefficients in a transform domain, thanks to a spatial light modulator. However, as measurements are sequential, only a few coefficients can be measured in the real-time applications. Therefore, single-pixel reconstruction is usually an underdetermined inverse problem that requires regulariza...

Spectral computed tomography acquires energy-resolved data that allows recovery of densities of constituents of an object. This can be achieved by decomposing the measured spectral projection into material projections, and passing these decomposed projections through a tomographic reconstruction algorithm, to get the volumetric mass density of each...

Introduction Les modalités d’imagerie qui aident à mieux comprendre le processus arthrosique sont la radiographie, l’IRM, la tomographie X, les ultrasons, la DXA et le TEP. À ce jour, seuls l’IRM et la tomographie sont des modalités tri-dimensionnelles (3D). L’analyse du cartilage sous forme de cartographie 3D ont été largement développé en IRM ave...

Introduction Les modalités d’imagerie qui aident à mieux comprendre le processus arthrosique sont la radiographie, l’IRM, la tomographie X, les ultrasons, la DXA et le TEP. A ce jour, seules l’IRM et la tomographie X sont des modalités tri-dimensionnelles (3D). Au niveau osseux, l’IRM permet surtout de visualiser l’existence d’un œdème sous chondra...

Current model-based variational methods used for solving the nonlinear material decomposition problem in spectral computed tomography rely on prior knowledge of the scanner energy response, but this is generally unknown or spatially varying. We propose a twostep deep transfer learning approach that can learn the energy response of the scanner and i...

Purpose The objective of this technical note was to investigate the accuracy of proton stopping power relative to water (RSP) estimation using a novel dual‐layer, dual‐energy computed tomography (DL‐DECT) scanner for potential use in proton therapy planning. DL‐DECT allows dual‐energy reconstruction from scans acquired at a single x‐ray tube voltag...

Compressed sensing reconstruction based on a prior image for fMRI

Electrical resistance tomography (ERT) is an imaging technique to recover the conductivity distribution with boundary measurements via attached electrodes. There are a wide range of applications using ERT for image reconstruction or parameter calculation due to high speed data collection, low cost, and the advantages of being non-invasive and porta...

Purpose Magnetic induction tomography (MIT) is a tomographic imaging technique with a wide range of potential industrial applications. Planar array MIT is a convenient setup but unable to access freely from the entire periphery as it only collects measurements from one surface, so it remains challenging given the limited data. This study aims to a...

In this paper, we address the resolution of material decomposition, which is a nonlinear inverse problem encountered in spectral computed tomography (CT). The problem is usually solved in a variational framework but, due to the nonlinearity of the forward operator, the objective function may be nonconvex and standard approaches may fail. Regularize...

Landmines are often be made out of plastic with almost no metallic components which makes detection difficult. A plausible solution is to detect superficial buried plastic objects using planar array Electrical Capacitance Tomography (ECT). Distance detection is a big limiting factor of planar array ECT. Given the ill-posedness and loss of sensitivi...

Electrical resistance tomography (ERT) has been considered as a data collection and image reconstruction method in many multi-phase flow application areas due to its advantages of high speed, low cost and being non-invasive. In order to improve the quality of the reconstructed images, the Total Variation algorithm attracts abundant attention due to...

Purpose: Exploiting the x-ray measurements obtained in different energy bins, spectral computed tomography (CT) has the ability to recover the 3-D description of a patient in a material basis. This may be achieved solving two subproblems, namely the material decomposition and the tomographic reconstruction problems. In this work, we address the ma...

We propose a regularized least-squares method for reconstructing 2D velocity vector fields within the left ventricular cavity from single-view color Doppler echocardiographic images. Vector flow mapping is formulated as a quadratic optimization problem based on an L2-norm minimization of a cost function composed of a Doppler data-fidelity term and...

Recent progress in X-ray CT is contributing to the advent of new clinical applications. A common challenge for these applications is the need for new image reconstruction methods that meet tight constraints in radiation dose and geometrical limitations in the acquisition. The recent developments in sparse reconstruction methods provide a framework...

Diffusion MRI measurements using hyperpolarized gases are generally acquired during patient breath hold, which yields a compromise between achievable image resolution, lung coverage and number of b-values. In this work, we propose a novel method that accelerates the acquisition of MR diffusion data by undersampling in both spatial and b-value dimen...

Diffusion MRI measurements using hyperpolarized gases are generally acquired during patient breath hold, which yields a compromise between achievable image resolution, lung coverage and number of b-values. In this work, we propose a novel method that accelerates the acquisition of MR diffusion data by undersampling in both spatial and b-value dimen...

Magnetic induction tomography (MIT) is an imaging modality with a wide range of potential applications due to its non-contact nature. MIT is a member of the electrical tomography family that faces the most difficult imaging challenges, due to its demanding measurement accuracy requirements and its difficult forward and inverse problems. This paper...

Electrical capacitance tomography (ECT) is an imaging technology used to reconstruct the permittivity distribution within the sensing region. So far, ECT has been primarily used to image non-conductive media only, since if the conductivity of the imaged object is high, the capacitance measuring circuit will be almost shortened by the conductivity p...

Low-dose protocols for respiratory gating in cardiothoracic small-animal imaging lead to streak artifacts in the images reconstructed with a Feldkamp-Davis-Kress (FDK) method. We propose a novel prior- and motion-based reconstruction (PRIMOR) method, which improves prior-based reconstruction (PBR) by adding a penalty function that includes a model...

This repository contains a demo that shows how to use a novel prior- and motion-based reconstruction (PRIMOR) method for respiratory gated CT, as presented in the paper A novel prior- and motion-based compressed sensing methods for small-animal respiratory gated CT. JFPJ Abascal, M Abella, E Marinetto, J Pascau, and M Desco. PLOS ONE 9;11(3):e01498...

This repository contains a demo that shows how to use Spatiotemporal Total Variation efficiently implemented using the Split Bregman formulation, as used in the paper: P Montesinos, J F P J Abascal, L Cussó, J J Vaquero, M Desco. Application of the compressed sensing technique to self-gated cardiac cine sequences in small animals. Magn Reson Med.,...

CODE AVAILABLE (DEMO): https://github.com/HGGM-LIM/Split Bregman PICCS_fMRI RAW DATA: http://biig.uc3m.es/fmri_rat_data/ ABSTRACT Purpose: Compressed sensing is a technique used to accelerate magnetic resonance imaging (MRI) acquisition without compromising image quality. While it has proven particularly useful in dynamic imaging procedures such...

CODE AVAILABLE (DEMO): https://github.com/HGGM-LIM/Split Bregman PICCS_fMRI RAW DATA: http://biig.uc3m.es/fmri_rat_data/ ABSTRACT Purpose: Compressed sensing is a technique used to accelerate magnetic resonance imaging (MRI) acquisition without compromising image quality. While it has proven particularly useful in dynamic imaging procedures such...

Respiratory gating helps to overcome the problem of breathing motion in cardiothoracic small-animal imaging by acquiring multiple images for each projection angle and then assigning projections to different phases. When this approach is used with a dose similar to that of a static acquisition, a low number of noisy projections are available for the...

Purpose Compressed sensing (CS) has been widely applied to prospective cardiac cine MRI. The aim of this work is to study the benefits obtained by including motion estimation in the CS framework for small-animal retrospective cardiac cine. Methods We propose a novel B-spline-based compressed sensing method (SPLICS) that includes motion estimation...

Self-gated cine sequences are a common choice for cardiac MRI in preclinical applications. The aims of our work were to apply the compressed sensing technique to IntraGateFLASH cardiac MRI studies on rats and to find the maximum acceleration factor achievable with this technique. Our reconstruction method extended the Split Bregman formulation to m...

Motion-Based Reconstruction (MBR) and Prior-Based Reconstruction (PBR) are compressed sensing approaches for cardiac cine MRI that achieve high acceleration factors by exploiting temporal sparsity based on a prior image. It would be appealing to reconstruct only the image variation with respect to the prior image, as this is sparser than the image...

Compressed Sensing (CS) techniques are becoming increasingly popular to speed up data acquisition in many modalities. However, most of CS theory is devoted to undetermined problems and there are few contributions that apply it to ill-posed problems. In this work we present a novel approach to CS for fluorescence diffuse optical tomography (fDOT), n...

Over the lasts years many works have addressed the potential of compressed sensing techniques to accelerate acquisition of cardiac MRI. However, most of these works claimed the achievement of acceleration factors solely based on simulated data or on fully sampled acquisition data retrospectively undersampled. In this work the practical feasibility...

Dual energy x-ray computed tomography (DECT) is a valuable research tool for both clinical and preclinical studies and a field of extensive research. Current implementations of DECT rely on the acquisition of two datasets either by using two source-detector pairs or by rapidly switching the kVp of the x-ray source between consecutive projections. B...

Dynamic PET images suffer from low signal-to-noise ratio (SNR), especially for fast contrast uptake measurements due to the small number of counts available in those time frames. In this work, we propose a 4D reconstruction method based on spatiotemporal total variation (ST-TV) which takes advantage of image redundancies in 4D. The 4D ST-TV method...

The acceleration of dynamic MRI studies such as fMRI would be a killing application of the recently developed compressed sensing techniques. We present the application of a spatiotemporal total variation reconstruction algorithm to undersampled rat fMRI series. In addition to the t maps extraction, a quantitative analysis of the percentage signal c...

Fluorescence diffuse optical tomography (fDOT) is a noninvasive imaging technique that makes it possible to quantify the spatial distribution of fluorescent tracers in small animals. fDOT image reconstruction is commonly performed by means of iterative methods such as the algebraic reconstruction technique (ART). The useful results yielded by more...

Respiratory gating is necessary in cardio-thoracic small-animal imaging because of the physiological motions that are present during scanning. When applying a low-dose protocol, fewer than 180 noisy projections may be left for the reconstruction of each respiratory phase, leading to streak artifacts. The Prior Image Constrained Compressed Sensing (...

Reconstruction algorithms for imaging fluorescence in near infrared ranges usually normalize fluorescence light with respect to excitation light. Using this approach, we investigated the influence of absorption and scattering heterogeneities on quantification accuracy when assuming a homogeneous model and explored possible reconstruction improvemen...

Standard image reconstruction methods for fluorescence Diffuse Optical Tomography (fDOT) generally make use of L2-regularization. A better choice is to replace the L2 by a total variation functional that effectively removes noise while preserving edges. Among the wide range of approaches available, the recently appeared Split Bregman method has bee...

Dynamic cardiac magnetic resonance imaging in small animals is an important tool in the study of cardiovascular diseases. The reduction of the long acquisition times required for cardiovascular applications is crucial to achieve good spatiotemporal resolution and signal-to-noise ratio. Nowadays there are many acceleration techniques which can reduc...

Fluorescence diffuse optical tomography (fDOT) is an imaging modality that provides images of the fluorochrome distribution within the object of study. The image reconstruction problem is ill-posed and highly underdetermined and, therefore, regularisation techniques need to be used. In this paper we use a nonlinear anisotropic diffusion regularisat...

Electrical impedance tomography is an imaging method, with which volumetric images of conductivity are produced by injecting electrical current and measuring boundary voltages. It has the potential to become a portable non-invasive medical imaging technique. Until now, most implementations have neglected anisotropy even though human tissues like bo...

Eddy-current nondestructive testing is widely used to detect defects within a metal structure. It is also useful to characterize their location and shape provided that proper maps of variations of impedance that the defects induce are available. Imaging of void defects in the wall of a hollow, nonmagnetic metal tube, is performed herein by controll...

The retrieval of a volumetric defect (singly- or multiply-connected) affecting the wall of a hollow metal tube is investigated from measurements of variations of impedances of an inner probe. Both non-ferromagnetic and ferromagnetic materials are taken into account in view of potential applications. This inverse problem is modeled as the estimation...

Electrical impedance tomography has the potential to provide a portable non-invasive method for imaging brain function. Clinical data collection has largely been undertaken with time difference data and linear image reconstruction methods. The purpose of this work was to determine the best method for selecting the regularization parameter of the in...

Electrical Impedance Tomography (EIT) is an imaging method which enables a volume conductivity map of a subject to be produced from multiple impedance measurements. It has the potential to become a portable non-invasive imaging technique of particular use in imaging brain function. Accurate numerical forward models may be used to improve image reco...

The retrieval of a volumetric defect (singly- or multiply-connected) affecting the wall of a hollow metal tube is investigated from measurements of variations of impedances of an inner probe. Both non-ferromagnetic and ferromagnetic materials are taken into account in view of potential applications. This inverse problem is modeled as the estimation...

Electrical Impedance Tomography has the potential to become a portable non-invasive medical imaging technique. Until now, implementations have neglected anisotropy even though human tissues like bone, muscle, and brain white matter are markedly anisotropic. We present a numerical solution using the finite element method that has been modified for m...

Electrical impedance tomography is an imaging method, with which volumetric images of conductivity are produced by injecting electrical current and measuring boundary voltages. It has the potential to become a portable non-invasive medical imaging technique. Until now, implementations have neglected anisotropy even though human tissues such as bone...

Electrical Impedance Tomography (EFT) is a relatively new medical imaging method which, by injecting current and measuring voltage, estimates a volume conductivity map of the sub ject. It has the potential to become a portable noninvasive imaging technique of particular use in imaging brain function. A good estimate of the modelling parameters is e...

Impedance Tomography (EIT) seeks to provide a portable non-invasive method for imaging brain function; one attractive application lies in assessing brain development in newborn infants by imaging blood flow responses to evoked physiological activity. However, in previous EIT studies, there was a low signal-to-noise ratio (SNR). In order to try and...

Electrical Impedance Tomography has the potential to become a portable non-invasive medical imaging technique. Until now, implementations have neglected anisotropyeven though human tissue like bone, muscle, and braine white matter are markedly anisotropic. We present a numerical solution the finite element method that has been modified for moddelin...

Electrical impedance tomography (EIT) has the potential to produce images during epileptic seizures. This might improve the accuracy of the localization of epileptic foci in patients undergoing presurgical assessment for curative neurosurgery. It has already been shown that impedance increases by up to 22% during induced epileptic seizures in anima...

The possible use of EIT for rapid neuroimaging in acute stroke is very attractive, as it could be used in Casualty or the community to distinguish haemorrhagic from ischaemic stroke and so permit the use of thrombolytic (clot-busting) drugs. In our group at UCL, we have been developing the UCLH Mk2 Multifrequency (MF) EIT system for this purpose (1...

Anisotropic conductivity arises in bio-medical EIT, for example in muscle tissue, however the anisotropic inverse conductivity problem can be solved uniquely only up to a diffeomorphism which fixes all points on the boundary. Although a scalar conductivity can be reconstructed from current and voltage measurements, extra information must be provide...