R.H. Menk

Mammography with Synchrotron Radiation: First Clinical Experience with Phase-Detection Technique

PURPOSE To prospectively evaluate the diagnostic contribution of mammography with synchrotron radiation in patients with questionable or suspicious breast abnormalities identified at combined digital mammography (DM) and ultrasonography (US). MATERIALS AND METHODS The ethics committee approved this prospective study, and written informed consent was obtained from all patients. Mammography with synchrotron radiation was performed with a phase-detection technique at a synchrotron radiation laboratory. Forty-nine women who met at least one of the inclusion criteria (palpable mass, focal asymmetry, architectural distortion, or equivocal or suspicious mass at DM; none clarified at US) were enrolled. Forty-seven women (mean age, 57.8 years ± 8.8 [standard deviation]; age range, 43-78 years) completed the study protocol, which involved biopsy or follow-up for 1 year as the reference standard. Breast Imaging Reporting and Data System (BI-RADS) scores of 1-3 were considered to indicate a negative result, while scores 4-5 were considered to indicate a positive result. The visibility of breast abnormalities and the glandular parenchymal structure at DM and at mammography with synchrotron radiation was compared by using the Wilcoxon signed rank test. RESULTS In 29 of the 31 patients with a final diagnosis of benign entity, mammography with synchrotron radiation yielded BI-RADS scores of 1-3. In 13 of the remaining 16 patients with a final diagnosis of malignancy, mammography with synchrotron radiation yielded BI-RADS scores of 4-5. Therefore, a sensitivity of 81% (13 of 16 patients) and a specificity of 94% (29 of 31 patients) were achieved with use of the described BI-RADS dichotomization system. CONCLUSION These study results suggest that mammography with synchrotron radiation can be used to clarify cases of questionable or suspicious breast abnormalities identified at DM. SUPPLEMENTAL MATERIAL http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11100745/-/DC1.

PITRE: software for phase-sensitive X-ray image processing and tomography reconstruction

Synchrotron-radiation computed tomography has been applied in many research fields. Here, PITRE (Phase-sensitive X-ray Image processing and Tomography REconstruction) and PITRE_BM (PITRE Batch Manager) are presented. PITRE supports phase retrieval for propagation-based phase-contrast imaging/tomography (PPCI/PPCT), extracts apparent absorption, refractive and scattering information of diffraction enhanced imaging (DEI), and allows parallel-beam tomography reconstruction for conventional absorption CT data and for PPCT phase retrieved and DEI-CT extracted information. PITRE_BM is a batch processing manager for PITRE: it executes a series of tasks, created via PITRE, without manual intervention. Both PITRE and PITRE_BM are coded in Interactive Data Language (IDL), and have a user-friendly graphical user interface. They are freeware and can run on Microsoft Windows systems via IDL Virtual Machine, which can be downloaded for free and does not require a license. The data-processing principle and some examples of application will be presented.

Functionalized gold nanoparticles: a detailed in vivo multimodal microscopic brain distribution study

In the present study, the in vivo distribution of polyelectrolyte multilayer coated gold nanoparticles is shown, starting from the living animal down to cellular level. The coating was designed with functional moieties to serve as a potential nano drug for prion disease. With near infrared time-domain imaging we followed the biodistribution in mice up to 7 days after intravenous injection of the nanoparticles. The peak concentration in the head of mice was detected between 19 and 24 h. The precise particle distribution in the brain was studied ex vivo by X-ray microtomography, confocal laser and fluorescence microscopy. We found that the particles mainly accumulate in the hippocampus, thalamus, hypothalamus, and the cerebral cortex.

In vivo visualization of gold-loaded cells in mice using x-ray computed tomography

UNLABELLED The ability to perform cell tracking using x-ray computed tomography combined with gold nanoparticles has been demonstrated recently on ex vivo samples using different malignant and nonmalignant cell lines. Here we proved the concept of the method for in vivo assessment in a small-animal model of malignant brain tumors. The limitations of the method due to radiation dose constraints were investigated using Monte Carlo simulations. Taking into consideration different x-ray entrance doses and the spatial resolution, the visibility of the cell clusters was evaluated. The results of the experiments conducted on mice implanted with F98 tumor cells confirmed the prediction of the Monte Carlo calculations. Small clusters of cells exogenously loaded with gold nanoparticles could be visualized using our in vivo method. FROM THE CLINICAL EDITOR This article discusses the use of CT-based detection of gold nanoparticle loaded cells of interest in small-animal models of malignant brain tumors, where small clusters of cells loaded with gold nanoparticles could be visualized.

Study and application of hole structures as gas gain devices for two dimensional high rate X-ray detectors

Abstract Recent developments in hole structures seem to be a promising enrichment for gas-filled photon counters. Up to now, only few investigations of the performance and limitations of these structures have been carried out. In this work a micro-hole structure is presented together with investigations focused on applications with position sensitive pressurized X-ray detectors for synchrotron radiation. In particular, position resolution, gas gain, rate capability, drift field influence and pressure behavior have been studied. In addition, first two dimensional X-ray images have been measured using a gas amplifying micro-hole structure in combination with a resistive position encoding structure. Since different types of hole structures were tested, predictions of structure geometries adapted for specific applications were carried out.

Double beam bent Laue monochromator for coronary angiography

High photon fluxes are crucial in dichromatic digital subtraction angiography with line scan systems to allow for adequate image quality. To obtain images wide enough and with sufficient vertical resolution, each of the two beams used has to be at least 100 mm wide but not more than 0.5 mm high at the patient’s heart with the beam energies bracketing the iodine‐K edge at 33.17 keV. A new monochromator in Laue transmission geometry has been developed, successfully tested at beamline ID11 of the European Synchrotron Radiation Facility (ESRF) and is now in use at the angiography wiggler beamline W2 at HASYLAB. The monochromator consists of two almost identical goniometer heads which are independently controlled. Within each head a bent silicon single crystal extracts a quasimonochromatic beam and focuses it vertically to the patient thus also increasing intensity compared to an unbent crystal. With a storage ring current of 50 mA the new monochromator provides 0.8×1011 photons/mm2/s in front of the patient w...

GAS AMPLIFYING HOLE STRUCTURES WITH RESISTIVE POSITION ENCODING : A NEW CONCEPT FOR A HIGH RATE IMAGING PIXEL DETECTOR

Abstract Promising recent developments in gas amplifying hole structures (e.g. CAT, MICROMEGAS, GEM) were accompanied by a lack of appropriate readout structures. Here, a new hole structure is presented which is combined, for the first time, with a truely two-dimensional resistive position encoding device. The investigations with this prototype detector are focused on applications with high rate X-ray sources, including general studies of gas gain, energy resolution and rate capability. In addition, latest results of the imaging performance (uniformity, spatial resolution, etc.) will be reported.

Multipurpose modular experimental station for the DiProI beamline of Fermi@Elettra free electron laser.

We present a compact modular apparatus with a flexible design that will be operated at the DiProI beamline of the Fermi@Elettra free electron laser (FEL) for performing static and time-resolved coherent diffraction imaging experiments, taking advantage of the full coherence and variable polarization of the short seeded FEL pulses. The apparatus has been assembled and the potential of the experimental setup is demonstrated by commissioning tests with coherent synchrotron radiation. This multipurpose experimental station will be open to general users after installation at the Fermi@Elettra free electron laser in 2011.

Evaluation of microbubble contrast agents for dynamic imaging with x-ray phase contrast

X-rays are commonly used as a means to image the inside of objects opaque to visible light, as their short wavelength allows penetration through matter and the formation of high spatial resolution images. This physical effect has found particular importance in medicine where x-ray based imaging is routinely used as a diagnostic tool. Increasingly, however, imaging modalities that provide functional as well as morphological information are required. In this study the potential to use x-ray phase based imaging as a functional modality through the use of microbubbles that can be targeted to specific biological processes is explored. We show that the concentration of a microbubble suspension can be monitored quantitatively whilst in flow using x-ray phase contrast imaging. This could provide the basis for a dynamic imaging technique that combines the tissue penetration, spatial resolution, and high contrast of x-ray phase based imaging with the functional information offered by targeted imaging modalities.

Gas gain and signal length measurements with a triple-GEM at different pressures of Ar-, Kr- and Xe-based gas mixtures☆

Abstract We investigate the gas gain behaviour of a triple-GEM configuration in gas mixtures of argon, krypton and xenon with 10% and 30% of carbon dioxide at pressures between 1 and 3 bar . Since the signal widths affect the dead time behaviour of the detector we present signal length measurements to evaluate the use of the triple-GEM in time-resolved X-ray imaging.