Free propagation phase-contrast breast CT provides higher image quality than cone-beam breast-CT at low radiation doses: a feasibility study on human mastectomies.

In this study we demonstrate the first direct comparison between synchrotron x-ray propagation-based CT (PB-CT) and cone-beam breast-CT (CB-CT) on human mastectomy specimens (N = 12) including different benign and malignant lesions. The image quality and diagnostic power of the obtained data sets were compared and judged by two independent expert radiologists. Two cases are presented in detail in this paper including a comparison with the corresponding histological evaluation. Results indicate that with PB-CT it is possible to increase the level of contrast-to-noise ratio (CNR) keeping the same level of dose used for the CB-CT or achieve the same level of CNR reached by CB-CT at a lower level of dose. In other words, PB-CT can achieve a higher diagnostic potential compared to the commercial breast-CT system while also delivering a considerably lower mean glandular dose. Therefore, we believe that PB-CT technique, if translated to a clinical setting, could have a significant impact in improving breast cancer diagnosis.

X-ray-Based 3D Virtual Histology-Adding the Next Dimension to Histological Analysis.

Histology and immunohistochemistry of thin tissue sections have been the standard diagnostic procedure in many diseases for decades. This method is highly specific for particular tissue regions or cells, but mechanical sectioning of the specimens is required, which destroys the sample in the process and can lead to non-uniform tissue deformations. In addition, regions of interest cannot be located beforehand and the analysis is intrinsically two-dimensional. Micro X-ray computed tomography (µCT) on the other hand can provide 3D images at high resolution and allows for quantification of tissue structures, as well as the localization of small regions of interest. These advantages advocate the use of µCT for virtual histology tool with or without subsequent classical histology. This review summarizes the most recent examples of virtual histology and provides currently known possibilities of improving contrast and resolution of µCT. Following a background in µCT imaging, ex vivo staining procedures for contrast enhancement are presented as well as label-free virtual histology approaches and the technologies, which could rapidly advance it, such as phase-contrast CT. Novel approaches such as zoom tomography and nanoparticulate contrast agents will also be considered. The current evidence suggests that virtual histology may present a valuable addition to the workflow of histological analysis, potentially reducing the workload in pathology, refining tissue classification, and supporting the detection of small malignancies.

Optimization of propagation-based x-ray phase-contrast tomography for breast cancer imaging.

The aim of this study was to optimise the experimental protocol and data analysis for in-vivo breast cancer x-ray imaging. Results are presented of the experiment at the SYRMEP beamline of Elettra Synchrotron using the propagation-based phase-contrast mammographic tomography method, which incorporates not only absorption, but also x-ray phase information. In this study the images of breast tissue samples, of a size corresponding to a full human breast, with radiologically acceptable x-ray doses were obtained, and the degree of improvement of the image quality (from the diagnostic point of view) achievable using propagation-based phase-contrast image acquisition protocols with proper incorporation of x-ray phase retrieval into the reconstruction pipeline was investigated. Parameters such as the x-ray energy, sample-to-detector distance and data processing methods were tested, evaluated and optimized with respect to the estimated diagnostic value using a mastectomy sample with a malignant lesion. The results of quantitative evaluation of images were obtained by means of radiological assessment carried out by 13 experienced specialists. A comparative analysis was performed between the x-ray and the histological images of the specimen. The results of the analysis indicate that, within the investigated range of parameters, both the objective image quality characteristics and the subjective radiological scores of propagation-based phase-contrast images of breast tissues monotonically increase with the strength of phase contrast which in turn is directly proportional to the product of the radiation wavelength and the sample-to-detector distance. The outcomes of this study serve to define the practical imaging conditions and the CT reconstruction procedures appropriate for low-dose phase-contrast mammographic imaging of live patients at specially designed synchrotron beamlines.

Microenvironmental interactions between endothelial and lymphoma cells: a role for the canonical WNT pathway in Hodgkin lymphoma.

The interaction between vascular endothelial cells (ECs) and cancer cells is of vital importance to understand tumor dissemination. A paradigmatic cancer to study cell-cell interactions is classical Hodgkin Lymphoma (cHL) owing to its complex microenvironment. The role of the interplay between cHL and ECs remains poorly understood. Here we identify canonical WNT pathway activity as important for the mutual interactions between cHL cells and ECs. We demonstrate that local canonical WNT signaling activates cHL cell chemotaxis toward ECs, adhesion to EC layers and cell invasion using not only the Wnt-inhibitor Dickkopf, tankyrases and casein kinase 1 inhibitors but also knockdown of the lymphocyte enhancer binding-factor 1 (LEF-1) and ß-catenin in cHL cells. Furthermore, LEF-1- and ß-catenin-regulated cHL secretome promoted EC migration, sprouting and vascular tube formation involving vascular endothelial growth factor A (VEGF-A). Importantly, high VEGFA expression is associated with a worse overall survival of cHL patients. These findings strongly support the concept that WNTs might function as a regulator of lymphoma dissemination by affecting cHL cell chemotaxis and promoting EC behavior and thus angiogenesis through paracrine interactions.

WNT5A: a motility-promoting factor in Hodgkin lymphoma.

Classical Hodgkin lymphoma (cHL) has a typical clinical manifestation, with dissemination involving functionally neighboring lymph nodes. The factors involved in the spread of lymphoma cells are poorly understood. Here we show that cHL cell lines migrate with higher rates compared with non-Hodgkin lymphoma cell lines. cHL cell migration, invasion and adhesion depend on autocrine WNT signaling as revealed by the inhibition of WNT secretion with the porcupine inhibitors Wnt-C59/IWP-2, but did not affect cell proliferation. While application of recombinant WNT5A or WNT5A overexpression stimulates HL cell migration, neither WNT10A, WNT10B nor WNT16 did so. Time-lapse studies revealed an amoeboid type of cell migration modulated by WNT5A. Reduced migration distances and velocity of cHL cells, as well as altered movement patterns, were observed using porcupine inhibitor or WNT5A antagonist. Knockdown of Frizzled5 and Dishevelled3 disrupted the WNT5A-mediated RHOA activation and cell migration. Overexpression of DVL3-K435M or inhibition of ROCK (Rho-associated protein kinase) by Y-27632/H1152P disrupted cHL cell migration. In addition to these mechanistic insights into the role of WNT5A in vitro, global gene expression data revealed an increased WNT5A expression in primary HL cells in comparison with normal B-cell subsets and other lymphomas. Furthermore, the activity of both porcupine and WNT5A in cHL cells had an impact on lymphoma development in the chick chorionallantoic membrane assay. Massive bleeding of these lymphomas was significantly reduced after inhibition of WNT secretion by Wnt-C59. Therefore, a model is proposed where WNT signaling has an important role in regulating tumor-promoting processes.

X-Ray based Lung Function measurement-a sensitive technique to quantify lung function in allergic airway inflammation mouse models.

In mice, along with the assessment of eosinophils, lung function measurements, most commonly carried out by plethysmography, are essential to monitor the course of allergic airway inflammation, to examine therapy efficacy and to correlate animal with patient data. To date, plethysmography techniques either use intubation and/or restraining of the mice and are thus invasive, or are limited in their sensitivity. We present a novel unrestrained lung function method based on low-dose planar cinematic x-ray imaging (X-Ray Lung Function, XLF) and demonstrate its performance in monitoring OVA induced experimental allergic airway inflammation in mice and an improved assessment of the efficacy of the common treatment dexamethasone. We further show that XLF is more sensitive than unrestrained whole body plethysmography (UWBP) and that conventional broncho-alveolar lavage and histology provide only limited information of the efficacy of a treatment when compared to XLF. Our results highlight the fact that a multi-parametric imaging approach as delivered by XLF is needed to address the combined cellular, anatomical and functional effects that occur during the course of asthma and in response to therapy.

Clinical application of low-dose phase contrast breast CT: methods for the optimization of the reconstruction workflow.

Results are presented of a feasibility study of three-dimensional X-ray tomographic mammography utilising in-line phase contrast. Experiments were performed at SYRMEP beamline of Elettra synchrotron. A specially designed plastic phantom and a mastectomy sample containing a malignant lesion were used to study the reconstructed image quality as a function of different image processing operations. Detailed evaluation and optimization of image reconstruction workflows have been carried out using combinations of several advanced computed tomography algorithms with different pre-processing and post-processing steps. Special attention was paid to the effect of phase retrieval on the diagnostic value of the reconstructed images. A number of objective image quality indices have been applied for quantitative evaluation of the results, and these were compared with subjective assessments of the same images by three experienced radiologists and one pathologist. The outcomes of this study provide practical guidelines for the optimization of image processing workflows in synchrotron-based phase-contrast mammo-tomography.

[Image-guided minimal-invasive cochlear implantation--experiments on cadavers]. / Navigationsgeführte minimal-invasive Cochlea-Implantation--Untersuchungen am humanen Felsenbein.

BACKGROUND: The accuracy of navigation systems can be improved significantly by using high-resolution flat panel-based Volume Computed Tomography (fpVCT) so that new surgical therapeutic concepts become feasible. A navigation-guided minimally-invasive cochleostomy places highest requirements on the accuracy of intraoperative navigation. METHODS: A flat-panel Volume Computed Tomograph (fpVCT) was used to scan four human temporal bones. The isometric voxel size was 200 microm. The preoperative planning was used to define an optimized drilling channel from the mastoid surface to the round window niche and the scala tympani providing a safety margin to critical anatomical structures such as facial nerve, chorda tympani, sigmoid sinus and posterior wall of auditory canal. The canal was drilled hand-operated with a navigated drill following the previously planned trajectory. Afterwards the drilled canal was imaged by fpVCT. Conventional dissection including mastoidectomy and posterior tympanotomy assured correct localization of the cochleostomy. RESULTS: Path planning took an average of 54 minutes (range 35-85 minutes). Installation took an average of 16 minutes (range 14-19 minutes). The drilling procedure itself took an average of 7.75 min (range 5-12 minutes.) The RMSE-values varied between 0.1 and 0.2 mm (Table 1). All four specimens showed a cochleostomy located at the scala tympani anterior inferior to the round window. The chorda tympani was damaged in one specimen--this was preoperatively planned as a narrow facial recess was encountered. The time needed for planning and system-installation could be reduced continuously. CONCLUSIONS: This feasibility study demonstrates that using current image-guided surgery technology in combination with fpVCT allows drilling of a minimally invasive channel to the cochlea with loco typico cochleostomy. The necessary accuracy of intraoperative navigation can be achieved by use of fpVCT (technical accuracy between 0.1 and 0.2 mm). Our results demonstrate the feasibility of a navigation-guided minimally-invasive cochleostomy loco typico. While we are enthused by this preliminary work, we recognize the barriers which exist in translation to clinical application. These include surgical issues (e.g. control of unexpected bleeding) and electrode issues (e.g. development of insertion tools).

[Determination of renal carcinoma progression in small animals by means of flat-panel volumetric computer tomography]. / Die Erfassung der Progression des Nierenzellkarzinoms in Kleintieren mittels Flachdetektor-Volumen-CT.

PURPOSE: We investigated the feasibility of using flat panel volumetric computer tomography (fpVCT) for the detection of orthotopically implanted renal carcinomas in nude mice. MATERIALS AND METHODS: One million renal cell carcinoma cells [A-498 line (Braunschweig, Germany), in 0.2 ml phosphate-buffered solution (PBS), pH 7.4] were injected into the left kidney of each of the eight nude mice. Each mouse was imaged twice (12 and 16 weeks after implantation) with fpVCT (GE prototype with circular gantry with two 1024 x 1024, 200 microm pixel size, aSi/CsI flat panel detector) after injection of 200 microl contrast medium to check for tumour spread. After 16 weeks the mice were killed and dissected, and the imaging findings in liver, kidneys and lung were compared with the macroscopic findings. RESULTS: No local evidence of tumour or of metastatic spread was seen on fpVCT after 12 weeks in any of the mice. After 16 weeks fpVCT revealed tumour growth in 6 of the 16 kidneys. Two mice had each developed a multifocal renal cell carcinoma and one mouse, a bilateral renal tumour manifestation. In one mouse liver metastases were seen. The fpVCT findings correlated well with the observations recorded in the pathological examination. CONCLUSION: fpVCT is an innovative and noninvasive imaging procedure that can be used for longitudinal investigation of tumour progression following orthotopic implantation of renal cell carcinoma to small animals. The use of a system of this kind will make a decisive contribution to reducing the number of animals used in experimental test projects.

In vivo imaging in experimental preclinical tumor research--a review.

The multiparametric molecular cell and tissue analysis in vitro and in vivo is characterized by rapid progress in the field of image generation technologies, sensor biotechnology, and computational modeling. Fascinating new potentials in unraveling the detailed functions of single cells, organs, and whole organisms are presently emerging and permit the close monitoring i.e. tumor development or basic cell development processes with an unprecedented multiplicity of promising investigative possibilities. To answer basic questions of in vivo tumor development and progression fluorescence based imaging techniques provide new insights into molecular pathways and targets. Genetic reporter systems (eGFP, DsRED) are available and high sensitive detection systems are on hand. These techniques could be used for in vitro assays and quantified e.g. by microscopy and CCD based readouts. The introduction of novel fluorescent dyes emitting in the near infrared range (NIR) combined with the development of sensitive detector systems and monochromatic powerful NIR-lasers for the first time permits the quantification and imaging of fluorescence and/or bioluminescence in deeper tissues. Laser based techniques particularly in the NIR-range (like two-photon microscopy) offer superb signal to noise ratios, and thus the potential to detect molecular targets in vivo. In combination with flat panel volumetric computed tomography (fpVCT), questions dealing e.g. with tumor size, tumor growth, and angiogenesis/vascularization could be answered noninvasively using the same animal. The resolution of down to 150 microm/each direction can be achieved using fpVCT. It is demonstrated by many groups that submillimeter resolutions can be achieved in small animal imaging at high sensitivity and molecular specificity. Since the resolution in preclinical small animal imaging is down to approximately 10 microm by the use of microCT and to subcellular resolutions using ( approximately 1 microm) microscope based systems, the advances of different techniques can now be combined to "multimodal" preclinical imaging and the possibilities for in vivo intravital cytometry now become within one's reach.

Three-dimensional, non-destructive visualization of vertical root fractures using flat panel volume detector computer tomography: an ex vivo in vitro case report.

AIM: To detect and to visualize radiographically vertical root fractures in extracted teeth with a prototype of a novel, high resolution, three-dimensional flat panel volume detector computer tomograph (FD-VCT) system. SUMMARY: Five teeth with root fillings and clinical symptoms such as fistulas and isolated periodontal pockets of 8 mm or more were extracted after dental radiography indicating lateral or periapical lesions. Vertical root fractures or cracks were suspected because of the symptoms and clinical findings were evident after extraction in all cases but fracture lines were not visible on routine dental radiographs acquired before extraction. The extracted teeth were explored with a prototype of a FD-VCT. Using the FD-VCT, in all cases vertical root fractures or crack lines could be detected clearly in different views, depiction-modes and cross-sections at a spatial resolution of 140 microm. The evaluation of the fracture lines and teeth could be performed in three-dimensional views. The FD-VCT findings were confirmed by detailed inspection of the extracted teeth. KEY LEARNING POINTS: The FD-VCT is an innovative diagnostic tool for non-destructive, three-dimensional evaluation of extracted teeth in pre-clinical and experimental studies. The FD-VCT allows precise visualization and evaluation of vertical root fractures or cracks in extracted teeth. Clinical application of the system may be possible if technical modifications reduce the exposure dose: the high resolution detector systems of the FD-VCT should be combined with radiation systems that focus the radiation to the area of interest.