Gelation Dynamics upon Pressure-Induced Liquid-Liquid Phase Separation in a Water-Lysozyme Solution.

Employing X-ray photon correlation spectroscopy, we measure the kinetics and dynamics of a pressure-induced liquid-liquid phase separation (LLPS) in a water-lysozyme solution. Scattering invariants and kinetic information provide evidence that the system reaches the phase boundary upon pressure-induced LLPS with no sign of arrest. The coarsening slows down with increasing quench depths. The g2 functions display a two-step decay with a gradually increasing nonergodicity parameter typical for gelation. We observe fast superdiffusive (γ ≥ 3/2) and slow subdiffusive (γ < 0.6) motion associated with fast viscoelastic fluctuations of the network and a slow viscous coarsening process, respectively. The dynamics age linearly with time τ ∝ tw, and we observe the onset of viscoelastic relaxation for deeper quenches. Our results suggest that the protein solution gels upon reaching the phase boundary.

Performance of a cryo-cooled crystal monochromator illuminated by hard X-rays with MHz repetition rate at the European X-ray Free-Electron Laser.

Due to the high intensity and MHz repetition rate of photon pulses generated by the European X-ray Free-Electron Laser, the heat load on silicon crystal monochromators can become large and prevent ideal transmission in Bragg diffraction geometry due to crystal deformation. Here, we present experimental data illustrating how heat load affects the performance of a cryogenically cooled monochromator under such conditions. The measurements are in good agreement with a depth-uniform model of X-ray dynamical diffraction taking beam absorption and heat deformation of the crystals into account.

Materials Imaging and Dynamics (MID) instrument at the European X-ray Free-Electron Laser Facility.

The Materials Imaging and Dynamics (MID) instrument at the European X-ray Free-Electron Laser (EuXFEL) facility is described. EuXFEL is the first hard X-ray free-electron laser operating in the MHz repetition range which provides novel science opportunities. The aim of MID is to enable studies of nano-structured materials, liquids, and soft- and hard-condensed matter using the bright X-ray beams generated by EuXFEL. Particular emphasis is on studies of structure and dynamics in materials by coherent scattering and imaging using hard X-rays. Commission of MID started at the end of 2018 and first experiments were performed in 2019.

Evaluation of ankle ligaments with CT: A feasibility study.

PURPOSE: This study aims to systematically investigate if normal ankle ligaments can be assessed with CT imaging, using MRI as reference standard. METHODS: 35 patients (mean age: 47 ±â€¯15 years; female n = 19) with combined CT and MRI exams and without MR-morphologic signs of ankle ligamental injury were retrospectively identified. 3 readers independently evaluated the syndesmotic, the lateral and medial ankle ligaments in terms of visibility on a 4-point Likert scale (0-3 points) in multiplanar MDCT images in standard bone kernel reconstructions. In consensus CT-based ligament density and thickness were measured and the appearance was rated for each ligament. Results were compared and validated with corresponding MRI images. RESULTS: Almost all ankle ligaments identified in MRI images could be adequately depicted in standard multiplanar bone kernel CT images with a mean visual score of 2.7/3 (± 0.2). Difficulties in CT morphological delineation of ankle ligaments occurred in cases of filiform TNL and TCL and in cases of concurrent soft tissue edema. Interreader agreement for the CT-assessment of ankle ligaments was excellent, with Fleiss Kappa values >0.8. Mean density of evaluated medial and lateral ankle ligaments was 68 ±â€¯2.9 HU, with substantially inter- and intraindividual variations. Thickness measurements and assessment of appearance of ankle ligaments showed a good concordance between CT and MRI. CONCLUSIONS: Assessment of normal ankle ligaments via standard CT in bone kernel reconstructions is feasible, with some restrictions concerning the medial collateral ligaments and in the presence of soft tissue edema.

A preclinical Talbot-Lau prototype for x-ray dark-field imaging of human-sized objects.

PURPOSE: Talbot-Lau x-ray interferometry provides information about the scattering and refractive properties of an object - in addition to the object's attenuation features. Until recently, this method was ineligible for imaging human-sized objects as it is challenging to adapt Talbot-Lau interferometers (TLIs) to the relevant x-ray energy ranges. In this work, we present a preclinical Talbot-Lau prototype capable of imaging human-sized objects with proper image quality at clinically acceptable dose levels. METHODS: The TLI is designed to match a setup of clinical relevance as closely as possible. The system provides a scan range of 120 × 30 cm2 by using a scanning beam geometry. Its ultimate load is 100 kg. High aspect ratios and fine grid periods of the gratings ensure a reasonable setup length and clinically relevant image quality. The system is installed in a university hospital and is, therefore, exposed to the external influences of a clinical environment. To demonstrate the system's capabilities, a full-body scan of a euthanized pig was performed. In addition, freshly excised porcine lungs with an extrinsically provoked pneumothorax were mounted into a human thorax phantom and examined with the prototype. RESULTS: Both examination sequences resulted in clinically relevant image quality - even in the case of a skin entrance air kerma of only 0.3 mGy which is in the range of human thoracic imaging. The presented case of a pneumothorax and a reader study showed that the prototype's dark-field images provide added value for pulmonary diagnosis. CONCLUSION: We demonstrated that a dedicated design of a Talbot-Lau interferometer can be applied to medical imaging by constructing a preclinical Talbot-Lau prototype. We experienced that the system is feasible for imaging human-sized objects and the phase-stepping approach is suitable for clinical practice. Hence, we conclude that Talbot-Lau x-ray imaging has potential for clinical use and enhances the diagnostic power of medical x-ray imaging.

[X­ray Phase Contrast : Principles, potential and advances in clinical translation]. / Röntgen-Phasenkontrast : Grundlagen, Potenzial und Fortschritte in der klinischen Translation.

More than 100 years ago Max von Laue in Munich discovered that X­rays can be interpreted not only as X­ray quanta in a particle picture, but also show a wave character. This property has been used for a long time in basic research (e.g. in crystallography for determining the structure of proteins), but so far has had no application in medical imaging. In the last 10 years, however, very impressive technological progress could be made in preclinical research, which also makes the utilization of the wave character of X­ray light possible for medical imaging. These novel radiography procedures, so-called phase-contrast and dark-field imaging, have a great potential for a pronounced improvement in X­ray imaging and therefore, also the diagnosis of important diseases. This article describes the basic principles of these novel procedures, summarizes the preclinical research results already achieved exemplified by various organs and shows the potential for future clinical utilization in radiography and computed tomography.

The diagnostic value of contrast-enhanced ultrasound (CEUS) as a new technique for imaging of vascular complications in renal transplants compared to standard imaging modalities.

BACKGROUND: Vascular complications in renal transplant patients are a well-known issue in post transplant patient care. If malfunctioning of the renal transplant is suspected to be caused by vascular complications an early diagnosis and therapy is required to maintain the renal transplant. Computed tomography (CT), digital substraction angiography (DSA) and radioisotope renography are the gold standard imaging modalities to diagnose vascular complications. OBJECTIVE: To analyse the sensitivity and specificity of contrast-enhanced ultrasound (CEUS) in comparison to the standard imaging modalities CT, DSA and radioisotope renography in the diagnosis of vascular complications in renal transplant patients. METHODS: A total of 33 renal transplant recipients with elevated kidney function parameters with initial diagnostic imaging between 2006 and 2017 were included in the study. The imaging studies and clinical data were analysed retrospectively. The diagnostic accuracy of CEUS was compared to CT, DSA and renal scintigraphy respectively which are classified as gold standard for diagnosis of vascular complications in renal transplant patients. Out of 23 patients 15 patients showed vascular complications in CT, DSA or radioisotope renography and in 15 out of 15 patients CEUS detected the vascular complication. RESULTS: CEUS showed a sensitivity of 100%, a specificity of 66.7%, a positive predictive value (PPV) of 71.4%, and a negative predictive value (NPV) of 100%. CONCLUSIONS: CEUS is a non-nephrotoxic and safe method for the initial imaging of vascular complications in renal transplant recipients. Compared to the gold standard imaging modalities CT, DSA and radioisotope renography CEUS shows a high sensitivity and NPV in detecting vascular complications. In cases with suspected stenosis of the transplant renal artery additional DSA might be needed.

The value of contrast-enhanced ultrasound (CEUS) using a high-end ultrasound system in the characterization of endoleaks after endovascular aortic repair (EVAR).

PURPOSE: To evaluate the value of contrast-enhanced ultrasound (CEUS) using a high-end ultrasound system in the characterization of endoleaks after endovascular aortic repair (EVAR). MATERIAL AND METHODS: In this mono-center study, 41 patients were retrospectively analyzed after being examined using a modern high-end ultrasound system (RS80A with Prestige, Samsung Medison Co., Ltd., Seoul, Korea). The maximum diameters of the aneurysms were measured in two planes (right-left and ventral-dorsal). The performance of Color Doppler in comparison to CEUS was evaluated and CEUS was considered as the gold standard in endoleaks detection. RESULTS: 41 patients were included in the study. Between June and December 2016, mostly male patients (n = 38; 92,7%) were examined, corresponding to the incidence of abdominal aortic aneurysms in the population. Average age was 75±8 years (range 58-100 years). Average diameter of the treated aneurysm-sacs was 5,04±1.5 cm (range 2.7-10.5 cm) in the right-left plane and 4,75±1.36 cm (range 2.8-8.9 cm) in the ventral-dorsal plane. Using CEUS as the gold standard endoleaks could be detected in 28 patients (68,3%) with 13 patients not showing an endoleak after EVAR. Color Doppler showed a sensitivity of 32.1%, a specificity of 92.3%, a positive predictive value (PPV) of 90.0% and a negative predictive value (NPV) of 38,7% compared to CEUS being the gold standard. CONCLUSION: CEUS after EVAR using a modern high-end ultrasound system is a fast and cost-effective imaging modality for the detection and follow-up of endoleaks with superior benefits compared to Color Doppler. CEUS remains the initial standard-of-care examination for follow-up.

Contrast-enhanced ultrasound (CEUS) prediction of focal liver lesions in patients after liver transplantation in comparison to histopathology results.

PURPOSE: To investigate the value of contrast-enhanced ultrasound (CEUS) in histologic prediction of focal liver lesions after liver transplantation. MATERIALS AND METHODS: 10 focal liver lesions in 10 patients after liver transplantation were scanned using CEUS and the CEUS results were compared with the histopathological results. RESULTS: Among 10 focal liver lesions, 7 proofed to be histopathological benign and 3 lesions proofed to be histopathological malignant. All lesions (100%) were correctly report as benign or malignant in the report of the CEUS examination. CONCLUSION: CEUS can be helpful in the differentiation of benign and malignant focal liver lesions in patients after liver transplantation and can be used in clinical management of focal liver lesions.

Diagnostic accuracy of contrast-enhanced ultrasound (CEUS) in monitoring vascular complications in patients after liver transplantation - diagnostic performance compared with histopathological results.

PURPOSE: To analyse the diagnostic performance of contrast-enhanced ultrasound (CEUS) in patients with vascular complications and transplant rejection compared to histopathological results. MATERIALS AND METHODS: Our study consisted of 45 retrospectively analysed patients that underwent liver transplantations between January 1993 and December 2015 and developed post-transplant vascular complications with transplant rejection. CEUS examinations took place between September 2006 and December 2015. CEUS findings were correlated with histopathological results. RESULTS: CEUS showed a sensitivity of 61.5%, a specificity of 100.0%, a positive predictive value (PPV) of 100.0% and a negative predictive value (NPV) of 86,5% in the detection of vascular complications with post-transplant rejection. 5 examinations were reported as normal whereas the histopathological result showed a transplant rejection (false-negative). CONCLUSION: CEUS might be a useful additional non-invasive technique for the assessment of vascular complications with post-transplant rejection in patients after liver transplantation.

[MRI of the prostate]. / MRT der Prostata.

New clinical and technological advances in the field of magnetic resonance imaging (MRI) and targeted image-guided biopsy techniques have significantly improved the detection, localization and staging as well as active surveillance of prostate cancer in recent years. Multiparametric MRI (mpMRI) is currently the main imaging technique for the detection, characterization and diagnostics of metastasizing prostate cancer and is of high diagnostic importance for local staging within the framework of the detection of prostate cancer.

[Contrast-enhanced ultrasound (CEUS) of the liver : Critical evaluation of use in clinical routine diagnostics]. / Kontrastverstärkter Ultraschall (CEUS) der Leber : Kritische Bewertung des Einsatzes in der Routinediagnostik.

CLINICAL/METHODICAL ISSUE: Focal liver lesions are common incidental findings in abdominal ultrasound diagnostics. STANDARD RADIOLOGICAL METHODS: Characterization of focal liver lesions solely based on b­mode and color duplex is not feasible in all cases. METHODICAL INNOVATIONS: Using contrast-enhanced ultrasound (CEUS) it is possible to dynamically visualize the vascularization of focal liver lesions, which enables the characterization of benign and malignant liver tumors. The advantages of CEUS are that ultrasound contrast media do not show renal, hepatic or cardiac toxicity and do not influence the thyroid gland. The approach by fusion of CEUS and contrast-enhanced cross-sectional imaging combines the advantages of both imaging modalities. PERFORMANCE: Using CEUS focal liver lesions can be characterized with a diagnostic accuracy greater than 90%. ACHIEVEMENTS: The use of CEUS has become an important imaging modality to evaluate unclear liver lesions. PRACTICAL RECOMMENDATIONS: The use of CEUS provides vital information as a supplement to cross-sectional imaging and it has become an important tool in therapy planning, control and monitoring of malignant liver lesions.

[Sonoelastography in daily clinical routine]. / Ultraschallelastographie in der klinischen Routinediagnostik.

CLINICAL ISSUE: In the daily clinical routine characterization of focal lesions using native B­mode classical ultrasound and color Doppler can be difficult or insufficient; therefore, additional diagnostic information must be taken into consideration. STANDARD RADIOLOGICAL METHODS: Standard radiological methods in the daily clinical routine include native B­mode ultrasound and color Doppler ultrasound. METHODICAL INNOVATIONS: Using sonoelastography it is possible to evaluate and characterize tissue properties and focal lesions regarding their stiffness to acquire additional information on a noninvasive basis. PERFORMANCE: Sonoelastography enables the differentiation between benign and malignant lesions especially in organs that can be easily evaluated using ultrasound. This particularly includes the liver, the thyroid gland, the breasts and the testicles. Regarding the liver, sonoelastography techniques can also be used for evaluation of the tissue flexibility in the diagnostics of fibrosis and cirrhosis. ACHIEVEMENTS: Nowadays, elastography is implemented into every modern ultrasound system and has been established as a supplementary examination technique to the conventional ultrasound techniques. PRACTICAL RECOMMENDATIONS: Sonoelastography should be used in cases with unclear findings as an additional noninvasive tool for the differentiation between benign and malignant lesions.