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Elisabeth Schültke,
Michael E Kelly,
Christian Nemoz, Stefan Fiedler,
Lissa Ogieglo,
Paul Crawford,
Jessica Paterson,
Cole Beavis,
Francois Esteve,
Thierry Brochard,
Michel Renier,
Herwig Requardt,
Dominique Dallery,
Geraldine Le Duc,
Kotoo Meguro
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ABSTRACT: Although the quality of imaging techniques available for neurovascular angiography in the hospital environment has significantly improved over the last decades, the equipment used for clinical work is not always suited for neurovascular research in animal models. We have previously investigated the suitability of synchrotron-based K-edge digital subtraction angiography (KEDSA) after intravenous injection of iodinated contrast agent for neurovascular angiography in radiography mode in both rabbit and pig models. We now have used the KEDSA technique for the acquisition of three-dimensional images and dual energy CT.
All experiments were conducted at the biomedical beamline ID 17 of the European Synchrotron Radiation Facility (ESRF). A solid state germanium (Ge) detector was used for the acquisition of image pairs at 33.0 and 33.3 keV. Three-dimensional images were reconstructed from an image series containing 60 single images taken throughout a full rotation of 360°. CT images were reconstructed from two half-acquisitions with 720 projections each.
The small detector field of view was a limiting factor in our experiments. Nevertheless, we were able to show that dual energy CT using the KEDSA technique available at ID 17 is suitable for neurovascular research in animal models.
European journal of radiology 08/2011; 79(2):323-7. · 2.65 Impact Factor
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Elisabeth Schültke, Stefan Fiedler,
Christian Nemoz,
Lissa Ogieglo,
Michael E Kelly,
Paul Crawford,
Francois Esteve,
Thierry Brochard,
Michel Renier,
Herwig Requardt,
Geraldine Le Duc,
Bernhard Juurlink,
Kotoo Meguro
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ABSTRACT: K-edge digital subtraction angiography (KEDSA) combined with the tunability of synchrotron beam yields an imaging technique that is highly sensitive to low concentrations of contrast agents. Thus, contrast agent can be administered intravenously, obviating the need for insertion of a guided catheter to deliver a bolus of contrast agent close to the target tissue. With the high-resolution detectors used at synchrotron facilities, images can be acquired at high spatial resolution. Thus, the KEDSA appears particularly suited for studies of neurovascular pathology in animal models, where the vascular diameters are significantly smaller than in human patients.
This feasibility study was designed to test the suitability of KEDSA after intravenous injection of iodine-based contrast agent for use in a pig model. Four adult male pigs were used for our experiments. Neurovascular angiographic images were acquired using KEDSA with a solid state Germanium (Ge) detector at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France.
After intravenous injection of 0.9 ml/kg iodinated contrast agent (Xenetix), the peak iodine concentrations in the internal carotid and middle cerebral arteries reached 35 mg/ml. KEDSA images in radiography mode allowed the visualization of intracranial arteries of less than 1.5mm diameter.
European journal of radiology 03/2009; 73(3):677-81. · 2.65 Impact Factor
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Jani Keyriläinen,
Manuel Fernández,
Marja-Liisa Karjalainen-Lindsberg,
Pekka Virkkunen,
Marjut Leidenius,
Karl von Smitten,
Petri Sipilä, Stefan Fiedler,
Heikki Suhonen,
Pekka Suortti,
Alberto Bravin
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ABSTRACT: This study was approved by the local research ethics committee, and patient informed consent was obtained. The purpose of this study was to demonstrate that high-spatial-resolution low-dose analyzer-based x-ray computed tomography (CT) can substantially improve the radiographic contrast of breast tissue in vitro when compared with that attained by using diagnostic mammography and CT. An excised human breast tumor was examined by using analyzer-based x-ray imaging with synchrotron radiation. The correspondence between analyzer-based x-ray images and diagnostic mammograms, CT images, and histopathologic findings was determined. Calcifications and fine details of soft tissue, which are at the contrast detection limit on diagnostic mammograms, are clearly visible on planar analyzer-based x-ray images. Analyzer-based x-ray CT yields high contrast from smoothly varying internal structures, such as tumorous mass lesions, corresponding to information on actual structures seen at histopathologic analysis. The mean glandular dose of 1.9 mGy in analyzer-based x-ray CT is approximately equivalent to the dose administered during single-view screening mammography. The improved visibility of mammographically indistinguishable lesions in vitro suggests that analyzer-based x-ray CT may be a valuable method in radiographic evaluation of the breast, thereby justifying further investigations.
Radiology 11/2008; 249(1):321-7. · 5.73 Impact Factor
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Alberto Bravin,
Jani Keyriläinen,
Manuel Fernández, Stefan Fiedler,
Christian Nemoz,
Marja-Liisa Karjalainen-Lindsberg,
Mikko Tenhunen,
Pekka Virkkunen,
Marjut Leidenius,
Karl von Smitten,
Petri Sipilä,
Pekka Suortti
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ABSTRACT: The aim of this study was to introduce high-resolution computed tomography (CT) of breast tumours using the diffraction-enhanced x-ray imaging (DEI) technique and to compare results with radiological and histo-pathological examinations. X-ray CT images of tumour-bearing breast tissue samples were acquired by monochromatic synchrotron radiation (SR). Due to the narrow beam and a large sample-to-detector distance scattering is rejected in the absorption contrast images (SR-CT). Large contrast enhancement is achieved by the use of the DEI-CT method, where the effects of refraction and scatter rejection are analysed by crystal optics. Clinical mammograms and CT images were recorded as reference material for a radiological examination. Three malignant and benign samples were studied in detail. Their radiographs were compared with optical images of stained histological sections. The DEI-CT images map accurately the morphology of the samples, including collagen strands and micro-calcifications of dimensions less than 0.1 mm. Histo-pathological examination and reading of the radiographs were done independently, and the conclusions were in general agreement. High-resolution DEI-CT images show strong contrast and permit visualization of details invisible in clinical radiographs. The radiation dose may be reduced by an order of magnitude without compromising image quality, which would make possible clinical in vivo DEI-CT with future compact SR sources.
Physics in Medicine and Biology 04/2007; 52(8):2197-211. · 2.83 Impact Factor
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ABSTRACT: The purpose of this work was to assess the imaging performance of an indirect conversion detector (taper optics CCD; FReLoN' camera) in terms of the modulation transfer function (MTF), normalized noise power spectrum (NNPS) and detective quantum efficiency (DQE). Measurements were made with a synchrotron radiation laminar beam at various monochromatic energies in the 20-51.5 keV range for a gadolinium-based fluorescent screen varying in thickness; data acquisition and analysis were made by adapting to this beam geometry protocols used for conventional cone beams. The pre-sampled MTFs of the systems were measured using an edge method. The NNPS of the systems were determined for a range of exposure levels by two-dimensional Fourier analysis of uniformly exposed radiographs. The DQEs were assessed from the measured MTF, NNPS, exposure and incoming number of photons. The MTF, for a given screen, was found to be almost energy independent and, for a given energy, higher for the thinnest screen. At 33 keV and for the 40 (100) microm screen, at 10% the MTF is 9.2 (8.6) line-pairs mm(-1). The NNPS was found to be different in the two analyzed directions in relation to frequency. Highest DQE values were found for the combination 100 microm and 25 keV (0.5); it was still equal to 0.4 at 51.5 keV (above the gadolinium K-edge). The DQE is limited by the phosphor screen conversion yield and by the CCD efficiency. At the end of the manuscript the results of the FReLoN characterization and those from a selected number of detectors presented in the literature are compared.
Journal of Synchrotron Radiation 06/2006; 13(Pt 3):260-70. · 2.73 Impact Factor
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Bernard Bertrand,
François Estève,
Hélène Elleaume,
Christian Nemoz, Stefan Fiedler,
Alberto Bravin,
Gilles Berruyer,
Thierry Brochard,
Michel Renier,
Jacques Machecourt,
William Thomlinson,
Jean-François Le Bas
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ABSTRACT: Synchrotron radiation angiography (SRA) is a novel tool for minimally invasive coronary artery imaging. The method uses subtraction of two images produced at energies bracketing the iodine K-edge after intravenous infusion of iodinated contrast agent. We investigated the accuracy of SRA for detecting in-stent restenosis (ISR).
We recruited 57 men, 4-6 months after successful PTCA. We visualized the right coronary artery (RCA) in 27 patients with 36 stented segments [12 segments with ISR>50% by quantitative coronary angiography (QCA)], and the left anterior descending artery (LAD) in 30 patients with 37 stented segments (10 ISR). SRA and QCA were performed within 2 days of each other. Two experienced observers unaware of QCA data evaluated the SRA results. Image quality was good or excellent in most patients. Global sensitivity was 64%, specificity was 95%, and positive and negative predictive values were approximately 85%. Inter-observer kappa concordance coefficient was 0.86. False negatives involved short eccentric lesions and superimposed segments, most frequently of the LAD. False positives occurred in intermediate stenoses slightly overestimated by SRA.
In men, this minimally invasive approach, using small radiation doses, detects significant ISR in the RCA, but the LAD poses difficulties because of superimposition with others structures.
European Heart Journal 08/2005; 26(13):1284-91. · 10.48 Impact Factor
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Manuel Fernández,
Jani Keyriläinen,
Ritva Serimaa,
Mika Torkkeli,
Marja-Liisa Karjalainen-Lindsberg,
Marjut Leidenius,
Karl von Smitten,
Mikko Tenhunen, Stefan Fiedler,
Alberto Bravin,
Thomas M Weiss,
Pekka Suortti
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ABSTRACT: Twenty-eight human breast tumour specimens were studied with small-angle x-ray scattering (SAXS), and 10 of those were imaged by the diffraction enhanced x-ray imaging (DEI) technique. The sample diameter was 20 mm and the thickness 1 mm. Two examples of ductal carcinoma are illustrated by histology images, DEI, and maps of the collagen d-spacing and scattered intensity in the Porod regime, which characterize the SAXS patterns from collagen-rich regions of the samples. Histo-pathology reveals the cancer-invaded regions, and the maps of the SAXS parameters show that in these regions the scattering signal differs significantly from scattering by the surrounding tissue, indicating a degradation of the collagen structure in the invaded regions. The DEI images show the borders between collagen and adipose tissue and provide a co-ordinate system for tissue mapping by SAXS. In addition, degradation of the collagen structure in an invaded region is revealed by fading contrast of the DEI refraction image. The 28 samples include fresh, defrosted tissue and formalin-fixed tissue. The d-values with their standard deviations are given. In the fresh samples there is a systematic 0.76% increase of the d-value in the invaded regions, averaged over 11 samples. Only intra-sample comparisons are made for the formalin-fixed samples, and with a long fixation time, the difference in the d-value stabilizes at about 0.7%. The correspondence between the DEI images, the SAXS maps and the histo-pathology suggests that definitive information on tumour growth and malignancy is obtained by combining these x-ray methods.
Physics in Medicine and Biology 08/2005; 50(13):2991-3006. · 2.83 Impact Factor
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ABSTRACT: The combination of X-ray 'propagation-based' and 'analyzer-based' phase-contrast imaging with a perfect crystal-analyzer is investigated. The image pattern produced using this 'hybrid' imaging technique presents peculiar features that can be interpreted as a mixture of the two independent phase-contrast signals. A quantitative analysis has been performed in terms of signal-to-noise ratio for the three techniques considered in this paper. Results show that in the 'hybrid imaging' technique this parameter has a weaker dependence on the angular alignment of the crystal analyser with respect to the 'analyser-based' imaging. This pioneering experiment indicates that this hybrid imaging technique might permit simultaneous advantage of the specific features of the two imaging methods to be taken.
Journal of Synchrotron Radiation 04/2005; 12(Pt 2):241-5. · 2.73 Impact Factor
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Elodie Pagot, Stefan Fiedler,
Peter Cloetens,
Alberto Bravin,
Paola Coan,
Kamel Fezzaa,
José Baruchel,
Jürgen Härtwig,
Karl von Smitten,
Marjut Leidenius,
Marja-Liisa Karjalainen-Lindsberg,
Jani Keyriläinen
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ABSTRACT: Two x-ray phase contrast imaging techniques are compared in a quantitative way for future mammographic applications: diffraction enhanced imaging (DEI) and phase propagation imaging (PPI). DEI involves, downstream of the sample, an analyser crystal acting as an angular filter for x-rays refracted by the sample. PPI simply uses the propagation (Fresnel diffraction) of the monochromatic and partially coherent x-ray beam over large distances. The information given by the two techniques is assessed by theoretical simulations and compared at the level of the experimental results for different kinds of samples (phantoms and real tissues). The imaging parameters such as the energy, the angular position of the analyser crystal in the DEI case or the sample to detector distance in the PPI case were varied in order to optimize the image quality in terms of contrast, visibility and figure of merit.
Physics in Medicine and Biology 03/2005; 50(4):709-24. · 2.83 Impact Factor
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Jean-François Adam,
Christian Nemoz,
Alberto Bravin, Stefan Fiedler,
Sam Bayat,
Sylvie Monfraix,
Gilles Berruyer,
Anne Marie Charvet,
Jean-François Le Bas,
Hélène Elleaume,
François Estève
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ABSTRACT: The authors previously provided evidence of synchrotron radiation computed tomography (SRCT) efficacy for quantitative in vivo brain perfusion measurements using monochromatic X-ray beams. However, this technique was limited for small-animal studies by partial volume effects. In this paper, high-resolution absolute cerebral blood volume and blood-brain barrier permeability coefficient measurements were obtained on a rat glioma model using SRCT and a CCD camera (47x47 microm2 pixel size). This is the first report of in vivo high-resolution brain vasculature parameter assessment. The work gives interesting perspectives to quantify brain hemodynamic changes accurately in healthy and pathological small animals.
Journal of Cerebral Blood Flow & Metabolism 03/2005; 25(2):145-53. · 5.01 Impact Factor
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ABSTRACT: Six excised human breast tissue specimens carrying benign and malignant tumours were examined with the diffraction-enhanced imaging technique. Diffraction-enhanced images were compared with diagnostic screen-film mammograms and the correlation with histological information of the specimens was established. The enhanced visibility of calcifications, some of which were smaller than 0.15 mm in diameter, is reported in detail. Fine details of the structures such as strands of collagen and contours between glandular and adipose tissue, which are barely visible at the contrast detection limit in the conventional absorption-based mammograms, are clearly visible in the diffraction-enhanced images. Microscopic study of the stained histopathological sections unequivocally confirms the correlation of the radiographic findings with the morphologic changes in specimens. An increased soft tissue contrast and a combination of information obtained with disparate diffraction-enhanced images provide better visibility of mammographically indistinguishable features. This kind of additional structural information of the breast tissue is required to improve assessment accuracy and earlier detection of the breast lesions. These advances in image quality make the method a very promising candidate for mammography.
European Journal of Radiology 03/2005; 53(2):226-37. · 2.61 Impact Factor
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[show abstract]
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ABSTRACT: Two x-ray phase contrast imaging techniques are compared in a quantitative way for future mammographic applications: diffraction enhanced imaging (DEI) and phase propagation imaging (PPI). DEI involves, downstream of the sample, an analyser crystal acting as an angular filter for x-rays refracted by the sample. PPI simply uses the propagation (Fresnel diffraction) of the monochromatic and partially coherent x-ray beam over large distances. The information given by the two techniques is assessed by theoretical simulations and compared at the level of the experimental results for different kinds of samples (phantoms and real tissues). The imaging parameters such as the energy, the angular position of the analyser crystal in the DEI case or the sample to detector distance in the PPI case were varied in order to optimize the image quality in terms of contrast, visibility and figure of merit.
Physics in Medicine and Biology 02/2005; 50(4):709. · 2.83 Impact Factor
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Jean-Fran|[ccedil]|ois Adam,
Christian Nemoz,
Alberto Bravin, Stefan Fiedler,
Sam Bayat,
Sylvie Monfraix,
Gilles Berruyer,
Anne Marie Charvet,
Jean-Fran|[ccedil]|ois Le Bas,
H|[eacute]|l|[egrave]|ne Elleaume,
Fran|[ccedil]|ois Est|[egrave]|ve
[show abstract]
[hide abstract]
ABSTRACT: The authors previously provided evidence of synchrotron radiation computed tomography (SRCT) efficacy for quantitative in vivo brain perfusion measurements using monochromatic X-ray beams. However, this technique was limited for small-animal studies by partial volume effects. In this paper, high-resolution absolute cerebral blood volume and blood–brain barrier permeability coefficient measurements were obtained on a rat glioma model using SRCT and a CCD camera (47 47 m2 pixel size). This is the first report of in vivo high-resolution brain vasculature parameter assessment. The work gives interesting perspectives to quantify brain hemodynamic changes accurately in healthy and pathological small animals.Keywords: BBB permeability, blood volume, brain tumors, high-resolution CT, small-animal imaging, synchrotron radiation
Journal of Cerebral Blood Flow & Metabolism 01/2005; 25(2):145-153. · 5.01 Impact Factor
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François Estève,
Hélène Elleaume,
Bernard Bertrand,
Anne Marie Charvet, Stefan Fiedler,
Géraldine Le Duc,
Stéphanie Corde,
Christian Nemoz,
Michel Renier,
Jean Louis Lefaix,
Jean Jacques Leplat,
Pekka Suortti,
William Thomlinson,
J F Le Bas
Academic Radiology 06/2002; 9 Suppl 1:S92-7. · 1.69 Impact Factor
