Measuring the regulation of keratin filament network dynamics.

The organization of the keratin intermediate filament cytoskeleton is closely linked to epithelial function. To study keratin network plasticity and its regulation at different levels, tools are needed to localize and measure local network dynamics. In this paper, we present image analysis methods designed to determine the speed and direction of keratin filament motion and to identify locations of keratin filament polymerization and depolymerization at subcellular resolution.

Signal and noise modeling in confocal laser scanning fluorescence microscopy.

Fluorescence confocal laser scanning microscopy (CLSM) has revolutionized imaging of subcellular structures in biomedical research by enabling the acquisition of 3D time-series of fluorescently-tagged proteins in living cells, hence forming the basis for an automated quantification of their morphological and dynamic characteristics. Due to the inherently weak fluorescence, CLSM images exhibit a low SNR. We present a novel model for the transfer of signal and noise in CLSM that is both theoretically sound as well as corroborated by a rigorous analysis of the pixel intensity statistics via measurement of the 3D noise power spectra, signal-dependence and distribution.

Comprehensive validation of computational fluid dynamics simulations of in-vivo blood flow in patient-specific cerebral aneurysms.

Purpose: Recently, image-based computational fluid dynamic (CFD) simulations have been proposed to investigate the local hemodynamics inside human cerebral aneurysms. It was suggested that the knowledge of the computed three-dimensional flow fields can be used to assist clinical risk assessment and treatment decision making. Therefore, it was desired to know the reliability of CFD for cerebral blood flow simulation, and be able to provide clinical feedback.

3D segmentation of keratin intermediate filaments in confocal laser scanning microscopy.

In this paper, we propose and compare different methods for the 3D segmentation of keratin intermediate filaments (KFs) in images acquired using confocal laser scanning microscopy (CLSM). KFs are elastic cables forming a complex scaffolding within epithelial cells. They are involved in many basic cell functions.

Gap detection in endoscopic video sequences using graphs.

In minimal invasive surgery (MIS) a complete and seamless inspection of organs, e.g. the urinary bladder, using video endoscopes is often required for diagnostics.

Inertial navigation system for bladder endoscopy.

The usage of video endoscopes in cystoscopic interventions of the urinary bladder impedes an intuitive navigation. Although image-based solutions such as panorama images can provide extended views of the surgical field, a real-time 3-D navigation is not supported. Furthermore, the integration of common tracking systems in ambulant clinics is often hindered due to low usability and high costs.

Computer-based classification of small colorectal polyps by using narrow-band imaging with optical magnification.

Background: Recent studies have shown that narrow-band imaging (NBI) is a powerful diagnostic tool for the differentiation between neoplastic and non-neoplastic colorectal polyps.

Objective: To develop a computer-based method for classification of colorectal polyps.

Design: A prospective study.

Activity quantification combining conjugate-view planar scintigraphies and SPECT/CT data for patient-specific 3-D dosimetry in radionuclide therapy.

Purpose: Three-dimensional dosimetry based on quantitative SPECT/CT has potential advantages over planar approaches, but may be impractical due to acquisition durations. We combine one SPECT/CT with improved quantification of multiple planar scintigraphies to shorten acquisitions.

Methods: A hybrid 2-D/3-D quantification technique is proposed, using SPECT/CT information for robust planar image quantification and creating virtual SPECTs out of conjugate-view planar scintigraphies; these are included in a 3-D absorbed dose calculation.

Design and implementation of multisteerable matched filters.

Image analysis problems such as feature tracking, edge detection, image enhancement, or texture analysis require thedetection of multi-oriented patterns which can appear at arbitrary orientations. Direct rotated matched filtering for feature detection is computationally expensive, but can be sped up with steerable filters. So far, steerable filter approaches were limited to only one direction.

Venous tree separation in the liver: graph partitioning using a non-ising model.

Entangled tree-like vascular systems are commonly found in the body (e.g., in the peripheries and lungs).

Simultaneous reconstruction of activity and attenuation for PET/MR.

Medical investigations targeting a quantitative analysis of the position emission tomography (PET) images require the incorporation of additional knowledge about the photon attenuation distribution in the patient. Today, energy range adapted attenuation maps derived from computer tomography (CT) scans are used to effectively compensate for image quality degrading effects, such as attenuation and scatter. Replacing CT by magnetic resonance (MR) is considered as the next evolutionary step in the field of hybrid imaging systems.

Phantom-based experimental validation of computational fluid dynamics simulations on cerebral aneurysms.

Purpose: Recently, image-based computational fluid dynamics (CFD) simulation has been applied to investigate the hemodynamics inside human cerebral aneurysms. The knowledge of the computed three-dimensional flow fields is used for clinical risk assessment and treatment decision making. However, the reliability of the application specific CFD results has not been thoroughly validated yet.

Geometric calibration of lens and filter distortions for multispectral filter-wheel cameras.

High-fidelity color image acquisition with a multispectral camera utilizes optical filters to separate the visible electromagnetic spectrum into several passbands. This is often realized with a computer-controlled filter wheel, where each position is equipped with an optical bandpass filter. For each filter wheel position, a grayscale image is acquired and the passbands are finally combined to a multispectral image.

Range flow in varying illumination: algorithms and comparisons.

We extend estimation of range flow to handle brightness changes in image data caused by inhomogeneous illumination. Standard range flow computes 3D velocity fields using both range and intensity image sequences. Toward this end, range flow estimation combines a depth change model with a brightness constancy model.

The keratin-filament cycle of assembly and disassembly.

Continuous and regulated remodelling of the cytoskeleton is crucial for many basic cell functions. In contrast to actin filaments and microtubules, it is not understood how this is accomplished for the third major cytoskeletal filament system, which consists of intermediate-filament polypeptides. Using time-lapse fluorescence microscopy of living interphase cells, in combination with photobleaching, photoactivation and quantitative fluorescence measurements, we observed that epithelial keratin intermediate filaments constantly release non-filamentous subunits, which are reused in the cell periphery for filament assembly.

Texture classification by modeling joint distributions of local patterns with gaussian mixtures.

Texture classification generally requires the analysis of patterns in local pixel neighborhoods. Statistically, the underlying processes are comprehensively described by their joint probability density functions (jPDFs). Even for small neighborhoods, however, stable estimation of jPDFs by joint histograms (jHSTs) is often infeasible, since the number of entries in the jHST exceeds by far the number of pixels in a typical texture region.

Local and global panoramic imaging for fluorescence bladder endoscopy.

Endoscopic treatment of bladder cancer is more and more often based on photodynamic diagnostics (PDD), a specialized endoscopic technique where a narrow-band bluish illumination causes tumors to fluoresce reddish. Contrast between tumors and healthy bladder tissue is thus noticeably increased compared to white light endoscopy. A downside of PDD is the low illumination power, which requires that the distance between endoscope and bladder wall be kept low, thus resulting in a small field of view (FOV).

Temperature responses of roots: impact on growth, root system architecture and implications for phenotyping.

Root phenotyping is a challenging task, mainly because of the hidden nature of this organ. Only recently, imaging technologies have become available that allow us to elucidate the dynamic establishment of root structure and function in the soil. In root tips, optical analysis of the relative elemental growth rates in root expansion zones of hydroponically-grown plants revealed that it is the maximum intensity of cellular growth processes rather than the length of the root growth zone that control the acclimation to dynamic changes in temperature.

Analysis of multiple orientations.

Estimation of local orientations in multivariate signals is an important problem in image processing and computer vision. This general problem formulation also covers optical flow estimation, which can be regarded as orientation estimation in space-time-volumes. Modelling a signal using only a single orientation, however, is often too restrictive, since occlusions and transparencies occur frequently, thus necessitating the modelling and analysis of multiple orientations.

Toward a multimodal cell analysis of brush biopsies for the early detection of oral cancer.

Background: This report describes what to the authors' knowledge is the first clinical application of semiautomated multimodal cell analysis (MMCA), a novel technique for the early detection of cancer for cases with a limited number of suspicious cells. In this clinical study, MMCA was applied to oral cancer diagnostics on brush biopsies. The MMCA approach was based on the sequential application of multiple stainings of identical, slide-based cells and repeated relocalizations and measurements of their diagnostic features, resulting in multiparametric features of individual cells.

Video-based measuring of quality parameters for tricuspid xenograft heart valve implants.

Defective heart valves are often replaced by implants in open-heart surgery. Both mechanical and biological implants are available. Among biological implants, xenograft ones-i.

Directional view interpolation for compensation of sparse angular sampling in cone-beam CT.

In flat detector cone-beam computed tomography and related applications, sparse angular sampling frequently leads to characteristic streak artifacts. To overcome this problem, it has been suggested to generate additional views by means of interpolation. The practicality of this approach is investigated in combination with a dedicated method for angular interpolation of 3-D sinogram data.

Multispectral filter-wheel cameras: geometric distortion model and compensation algorithms.

Multispectral image acquisition considerably improves color accuracy in comparison to RGB technology. A common multispectral camera design concept features a filter-wheel consisting of six or more optical bandpass filters. By shifting the filters sequentially into the optical path, the electromagnetic spectrum is acquired through the channels, thus making an approximate reconstruction of the spectrum feasible.

Timing and targeting of cell-based VEGF165 gene expression in ischemic tissue.

Background: Therapeutic angiogenesis has become a key technology in experimental and clinical medicine. Only few data are available on the effects of timing and targeting of therapeutic proteins after cell-based gene transfer. This work investigates such effects after temporary expression of vascular endothelial growth factor 165 (VEGF(165)), the most commonly used angiogenic protein for therapeutic purposes.

Computer-assisted diagnosis for early stage pleural mesothelioma: towards automated detection and quantitative assessment of pleural thickening from thoracic CT images.

Objectives: Pleural thickenings as biomarker of exposure to asbestos may evolve into malignant pleural mesothelioma. For its early stage, pleurectomy with perioperative treatment can reduce morbidity and mortality. The diagnosis is based on a visual investigation of CT images, which is a time-consuming and subjective procedure.