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A critical issue in Deformable Registration (DR) is its validation due to the lack of a gold standard in clinical practice. We analyze Scale Invariant Feature Transform (SIFT) to quantify its potential as a tool for DR assessment. For this purpose we preliminary verify SIFT properties on both rigid and non-rigid phantoms and then apply it to evaluate DR in Head&Neck Adaptive Radiation Therapy...
Phase-contrast MRI (PC MRI) is a powerful technique for imaging the flow velocities in-vivo. In PC MRI, the velocity encoding parameter, Venc, plays a central role in fidelity of velocities acquired with this technique. Typically Venc is chosen to be the highest velocity in the flow. However, when acquiring velocity images at a number of slice locations, it may be advantageous to change the Venc as...
This paper presents a 3D reconstruction method of coronary arteries from multiple projections, that works efficiently in two steps: first, a 2D processing is performed to obtain and classify the vessels branches on the projections, estimating also the radii. Then, a novel 3D reconstruction step is performed from pair of projections, finding the best intersections between ray bundles corresponding...
This paper describes a realistic cardiac MR perfusion simulator; both the kinematic model of the perfusion process as well as breathing effects are described and a novel model for the AIF is proposed. Additionally the most common degradation factors involved in the MR image formation, such as those derived from parallel acquisition protocols, the presence of thermal noise and its correlation, the...
Compressed sensing (CS) has been successfully applied to accelerate conventional magnetic resonance imaging (MRI) with Fourier encoding. Total variation (TV) is usually used as the regularization function for image reconstruction. However, it is know that such ℓ1-based minimization algorithm needs more measurements than the ℓ0-based ones. On the other hand, ℓ0-based minimization is computational intractable...
This article presents a segmentation approach based on random walk (RW) method to delineate tumors having inhomogeneous activity distributions of 18FDG on Positron Emission Tomography (PET) images. Based on the original algorithm of RW [1], we propose an improved approach using an adaptive parameter instead of a fixed one and integrating probability densities of label into the system of linear equations...
The use of ultrasound imaging for image guidance of cardiac procedures is limited by the small field of view of the ultrasound volume. A larger view can be created by image-based registration of partially overlapping volumes, but automatic registration often fails unless the volume alignment is initialised close to the volumes' correct alignment. In this paper, we use X-ray images to track a trans-esophageal...
Circular holography is a novel reconstruction technique for Breast Microwave Radar (BMR) imaging. Compared to current state of the art BMR image formation methods, this reconstruction approach yields spatially accurate images with higher signal to noise ratios and no artifacts. Nevertheless, a preclinical study is required to assess the feasibility of this technique in realistic breast imaging scenarios...
This paper is an extension of our ISBI 2011 work, where we proposed a novel variational approach to estimate dense myocardial velocity fields from 4D ultrasound (4DUS). In this paper, we present a thorough performance evaluation of our method by comparing it with the primary method of record, which relies on cross-correlation. Our comparative performance evaluation uses several data sources, including...
We consider the problem of aligning high angular resolution diffusion images characterized by orientation distribution functions (ODFs). We cast this problem as an optimization problem where we seek the rotation that aligns the source and target ODFs. This rotation induces a linear transformation of the spherical harmonic coefficients of the ODFs, which can be parametrized by the rotation Euler angles...
The Alzheimer's Disease Neuroimaging Initiative (ADNI) employed phantom-based scaling of T1-weighted MP-RAGE brain images to improve spatial calibration of scans and longitudinal stability across study sites. Early in ADNI, errors in phantom based scaling were identified due to incorrect acquisition protocols or replacement of phantoms. Images initially made available with questionable scaling factors...
In this paper, we present a novel C-arm calibration approach for orthopedic applications that is based on a distortion correction plate with fiducials arranged in a single-plane and a novel mobile phantom. The former is designed to be rigidly attached to the image intensifier and is used together with a statistical model of the geometrical image distortion pattern for intra-operative image distortion...
A novel and efficient method to simulate the behavior of guidewires in the vascular system is proposed in this paper. The graph-theoretical method is based on the principle of minimal total potential energy. We formulate the total potential energy in the vascular interventional system as the summation of the elastic energy of the guidewire and the energy due to the deformation of the vessel wall....
Pharmacokinetic (PK) modeling of tumors provides information about perfusion and vascular permeability of tumors. Identifying arterial input function (AIF) is crucial in PK modeling using dynamic contrast enhanced (DCE)-MRI. An adaptive complex independent component analysis method is developed to identify and separate AIF from complex DCE-MRI data. The results are compared with a previously introduced...
In digital tomosynthesis (DTS), accurate scatter correction is often necessary for quantitative analysis. This is especially important because low energy x-ray of 10–40 keV, which is widely used for the breast imaging to enhance the contrast between adipose and glandular, results in high scatter fraction. In this paper, we propose an iterative scatter correction for digital tomopsynthesis using composition...
Cardiac gated SPECT imaging suffers from several degrading factors including limited data counts, depth-dependent blur, attenuation, scatter, and motion blur. In recent work we demonstrated that use of temporal processing could lead to the most improvement in 4D reconstruction. In this work we investigate how motion estimation models can affect the reconstruction in 4D, and in particular, we examine...
The dynamics of vesicle trafficking via the cell membrane and the tracking of their subsequent movements within the cell are of great interest in the biomedical sciences. One challenge of image analysis is following the vesicle's fate continuously from its formation at the membrane to its final destination, as it requires different microscopy techniques to image the complete journey. Total internal...
To reduce noise within a tag line, unsharpen tag edges in the spatial domain, and amplify the tag-to-background contrast, a 3D energy minimization framework for the enhancement of tagged Cardiac Magnetic Resonance (CMR) images, that is based on first- and second-order learned visual appearance models, is proposed. The first-order appearance modeling uses an adaptive Linear Combination of Discrete...
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