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.

[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.

[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.

Postmortem computed tomography (PMCT) and autopsy in deadly gunshot wounds--a comparative study.

INTRODUCTION: Postmortem computed tomography (PMCT) data in gunshot-related death were evaluated by two reader groups and compared to the gold standard autopsy for the determination of forensic pathology criteria. MATERIALS AND METHODS: Reader group I consisted of two board-certified radiologists whereas one board-certified radiologist and one board-certified forensic pathologist formed group II. PMCT data of 51 gunshot-related deaths were evaluated for the forensic pathology criteria number of gun shots, localization of gunshot injury, caliber, and direction of the gunshot differentiating between entry and exit wound as well as associated injury to surrounding tissue. The results of both reader groups were compared to the each other and to autopsy findings considered as gold standard. RESULTS: Reader groups I and II and as gold standard the autopsy evaluation showed in general a good correlation between all results. The overall discrepancy rate was 12/51 (23.4%) cases for group I and 8/51 (15.6%) for group II. DISCUSSION: Ultimately, the designated reader is able to draw the following conclusion from the presented data. At first, physical autopsy is better than PMCT regarding the localization of most gunshot injuries. Second, PMCT presents with better results than physical autopsy in locating fragmented bullets/fragment clouds, and finally, PMCT results of two radiologists were equivalent to the results of one evaluating radiologist and one pathologist with the exception of caliber assessment. However, referring to the pure numbers, the slight but not significant difference in the overall discrepancy rate of both reader groups might indicate the advantage of combining expertise in evaluating imaging in cases of gunshot-related death.

Contrast-Enhanced Ultrasound (CEUS) of the Kidneys by Using the Bosniak Classification.

Ultrasound is the most used interdisciplinary non-ionizing imaging technique in clinical routine. Therefore, ultrasound has a special value in the diagnosis and monitoring of cystic renal lesions, which can be classified as non-complicated or complicated and by means of occurrence as solitary or multifocal lesions. The Bosniak classification (I-IV) classifies renal cysts in 5 different categories with the help of ultrasound and computed tomography image criteria and is used for decisions of further clinical treatment. Additionally to normal native B-mode sonography, several new methods are in clinical use to improve diagnostic accuracy of unclear cases. Contrast enhanced ultrasound and MRI/CT are able to find and characterize difficult pathologies. This review explains the most important pathologies of cystic lesions of the kidney and stresses the different imaging methods of native B-mode sonography and the new techniques of contrast enhanced ultrasound.

[Stent-assisted recanalization of femoropopliteal arterial occlusive disease. Influence of stent design on patency rates]. / Stentgestützte Rekanalisation der femoropoplitealen arteriellen Verschlusskrankheit. Einfluss des Stentdesigns auf die Offenheitsrate.

BACKGROUND: Despite enormous technical progress the results of endovascular treatment of the femoropopliteal vasculature are unsatisfactory and its role is still controversially discussed. In the past decade numerous new stent designs have come onto the market but it is unclear whether they have benefits with respect to patency rates. OBJECTIVES: Comparison of published data on patency rates and target lesion revascularization rates after use of different stent designs in the femoropopliteal vasculature. MATERIAL AND METHODS: Analysis of 25 published studies and registries from 2006 to 2015 for classical open-cell stents, interwoven stents and partially or fully covered stents. RESULTS AND CONCLUSION: The published data are heterogeneous and comparative studies for different stent designs are completely missing. Over the past decade the patency rates after femoropopliteal stenting could be improved. According to available data stenting of short lesions < 5 cm does not show any benefit compared to isolated balloon angioplasty. Primary stenting is now recommended for intermediate and longer lesions > 6.4 cm. Due to the heterogeneity of published data a clear benefit for a specific stent design is not obvious; however, data for interwoven stents are promising and show a tendency towards improved patency, at least for certain lesions. Randomized controlled comparative trials are needed to confirm this result.

[Changing the internal cost allocation (ICA) on DRG shares : Example of computed tomography in a university radiology setting]. / Umstellung der internen Leistungsverrechnung (ILV) auf DRG-Anteile : Beispiel der Computertomographie einer universitären Radiologie.

BACKGROUND: In hospitals, the radiological services provided to non-privately insured in-house patients are mostly distributed to requesting disciplines through internal cost allocation (ICA). In many institutions, computed tomography (CT) is the modality with the largest amount of allocation credits. OBJECTIVES: The aim of this work is to compare the ICA to respective DRG (Diagnosis Related Groups) shares for diagnostic CT services in a university hospital setting. MATERIALS AND METHODS: The data from four CT scanners in a large university hospital were processed for the 2012 fiscal year. For each of the 50 DRG groups with the most case-mix points, all diagnostic CT services were documented including their respective amount of GOÄ allocation credits and invoiced ICA value. As the German Institute for Reimbursement of Hospitals (InEK) database groups the radiation disciplines (radiology, nuclear medicine and radiation therapy) together and also lacks any modality differentiation, the determination of the diagnostic CT component was based on the existing institutional distribution of ICA allocations. RESULTS: Within the included 24,854 cases, 63,062,060 GOÄ-based performance credits were counted. The ICA relieved these diagnostic CT services by € 819,029 (single credit value of 1.30 Eurocent), whereas accounting by using DRG shares would have resulted in € 1,127,591 (single credit value of 1.79 Eurocent). The GOÄ single credit value is 5.62 Eurocent. CONCLUSIONS: The diagnostic CT service was basically rendered as relatively inexpensive. In addition to a better financial result, changing the current ICA to DRG shares might also mean a chance for real revenues. However, the attractiveness considerably depends on how the DRG shares are distributed to the different radiation disciplines of one institution.

[Differentiation between acute osteoporotic and metastatic vertebral body fractures by imaging]. / Unterscheidung akuter osteoporotischer und metastasenbedingter Wirbelkörperfrakturen in der Bildgebung.

OBJECTIVES: This article discusses the morphological criteria for the differentiation between acute osteoporotic and metastatic vertebral body fractures and new imaging methods, such as diffusion-weighted and chemical shift magnetic resonance imaging (MRI) are presented. BACKGROUND: The differential diagnostics of osteoporotic and metastatic vertebral body fractures can be difficult in some cases. Both entities normally occur without adequate trauma and predominantly in elderly patients. IMAGING: Conventional X-ray examination is the initial imaging method of choice but is not able to reliably differentiate between the osteoporotic or metastatic etiology of a fracture. Computed tomography (CT) clearly depicts osseous destruction in metastatic fractures but lacks specificity. Magnetic resonance imaging (MRI) shows a higher sensitivity and specificity in differentiating osteoporotic and metastatic fractures. DIFFERENTIAL DIAGNOSTICS: The combination CT and MRI allows an accurate diagnosis with respect to an osteoprorotic or metastatic etiology in most of cases but bone marrow edema in acute fractures sometimes leads to ambiguous results and differential diagnostic problems.

[New Applications and Indications for Contrast-Enhanced Sonography in Endovascular Aortic Repair]. / Neue Applikationen und Indikationen der Kontrastmittelsonografie im Rahmen des Aortenstentings.

After edovascular repair of infrarenal aortic aneurysms (EVAR) endoleaks may occur necessitating further therapy. Therefore a reliable method for follow-up imaging after EVAR for detection and control of endoleaks is of high importance. Contrast-enhanced sonography (CEUS) does not require the application of nephrotoxid contrast media and does not stress the patient. CEUS is increasingly used and enables a quick, non-invasive follow-up examination for patient after EVAR. In addition, interventions as therapy for endoleaks may be executed using ultrasound. Initial experience with CEUS-guided aortic stenting shows that the amount of contrast media as well as X-ray time may be reduced.

Role of diffusion-weighted MRI in differentiation of hepatic abscesses from non-infected fluid collections.

AIM: To evaluate the role of diffusion-weighted magnetic resonance imaging (DW-MRI) in the differentiation of hepatic abscesses from non-infected fluid collections. MATERIALS AND METHODS: In this retrospective study, 22 hepatic abscesses and 27 non-infected hepatic fluid collections were examined in 27 patients who underwent abdominal MRI including DW-MRI. Two independent observers reviewed T2-weighted + DW-MRI and T2-weighted + contrast-enhanced T1-weighted (CET1W) images in two sessions. Detection rates and confidence levels were calculated and compared using McNemar's and Wilcoxon's signed rank tests, respectively. Apparent diffusion coefficient (ADC) values of abscesses and non-infected fluid collections were compared using the t-test. Receiver operating characteristic (ROC) curves were constructed. RESULTS: There was no statistically significant difference in the accuracy of detecting abscesses using T2-weighted + DW-MRI (both observers: 21/22, 95.5%) versus T2-weighted + CET1W images (observer 1: 21/22, 95.5%; observer 2: 22/22, 100%; p < 0.01). Mean ADC values were significantly lower with abscesses versus non-infected fluid collections (0.83 ± 0.24 versus 2.25 ± 0.61 × 10(-3) mm(2)/s; p < 0.001). With ROC analysis there was good discrimination of abscess from non-infected fluid collections at a threshold ADC value of 1.36 × 10(-3) mm(2)/s. CONCLUSION: DW-MRI allows qualitative and quantitative differentiation of abscesses from non-infected fluid collections in the liver.

Contrast-induced acute kidney injury after computed tomography prior to transcatheter aortic valve implantation.

AIM: To identify independent predictors of contrast medium-induced acute kidney injury (CI-AKI) after enhanced multidetector-row computed tomography (MDCT) prior to transcatheter aortic valve implantation (TAVI) in high-risk patients. MATERIALS AND METHODS: The present single-centre study analysed retrospectively 361 patients who were assessed using MDCT prior to TAVI. CI-AKI was defined as an increase in serum creatinine (SCr) of ≥ 25% or ≥ 0.5 mg/dl in at least one sample over baseline (24 h before MDCT) and at 24, 48, and 72 h after MDCT. RESULTS: A total of 38 patients (10.5%) experienced CI-AKI. As compared to patients without CI-AKI, they presented more frequently with estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m(2), (81.6% versus 64.4%, p = 0.045) and tended to receive higher volumes of iodinated contrast media (ICM; 55.3% versus 39%, p = 0.057). There was a significant interaction between baseline eGFR and the amount of intravenous ICM administered (pfor interaction = <0.001) identifying the amount of ICM >90 ml as independent predictive factor of CI-AKI only in patients with baseline eGFR <60 ml/min/1.73m(2) (OR 2.615; 95% CI: 1.21-5.64). CONCLUSION: One in ten elderly patients with aortic stenosis undergoing MDCT to plan a TAVI procedure experienced CI-AKI after intravenous ICM injection. Intravenous administration of <90 ml of ICM reduces this risk in patients with or without pre-existing impaired renal function. However, in the majority of patients renal function recovers before the TAVI procedure.

The role of follow-up ultrasound and clinical parameters after abdominal MDCT in patients with multiple trauma.

BACKGROUND: Beside its value during the initial trauma work-up (focused assessment with sonography for trauma), ultrasound (US) is recommended for early follow-up examinations of the abdomen in multiple injured patients. However, multidetector CT (MDCT) has proven to reliably diagnose traumatic lesions of abdominal organs, to depict their extent, and to assess their clinical relevance. PURPOSE: To evaluate the diagnostic impact of follow-up US studies after MDCT of the abdomen and to identify possible clinical parameters indicating the need of a follow-up US. MATERIAL AND METHODS: During a 30-month period, patients with suspected multiple trauma were allocated. Patients with admission to the ICU, an initial abdominal MDCT scan, and an US follow-up examination after 6 and 24 h were included. Two patient cohorts were defined: patients with normal abdominal MDCT (group 1), patients with trauma-related pathologic abdominal MDCT (group 2). In all patients, parameters indicating alteration of vital functions or hemorrhage within the first 24 h were obtained by reviewing the medical charts. RESULTS: Forty-four of 193 patients were included: 24 were categorized in group 1 (mean age, 41.1 years; range, 21-90 years), 20 in group 2 (mean age, 36.6 years; range, 16-71 years). In group 1, US did not provide new information compared to emergency MDCT. In group 2, there were no contradictory 6- and 24-h follow-up US findings. In patients with positive MDCT findings and alterations of clinical parameters, US did not detect progression of a previously diagnosed pathology or any late manifestation of such a lesion. In none of the patients with negative abdominal MDCT and pathological clinical parameters US indicated an abdominal injury. CONCLUSION: Routine US follow-up does not yield additional information after abdominal trauma. In patients with MDCT-proven organ lesions, follow-up MDCT should be considered if indicated by abnormal clinical and/or laboratory findings.

[Gastroenteropancreatic endocrine tumors]. / Gastroenteropankreatische endokrine Tumoren.

CLINICAL/METHODICAL ISSUE: Gastroenteropancreatic neuroendocrine tumors (GEP-NET) are a rare, heterogeneous group of neoplasms. Only 2% of gastrointestinal tumors belong to the group of neuroendocrine neoplasms. STANDARD RADIOLOGICAL METHODS: A wide spectrum of diagnostic imaging modalities is available: apart from ultrasound not only computed tomography (CT) but also magnetic resonance imaging (MRI) and positron emission tomography CT (PET-CT) play an important role in detection and staging of GEP-NETs. METHODICAL INNOVATIONS: The PET-CT technique with somatostatin analogues is used for staging as well as for evaluation and monitoring of treatment with peptide radionuclide radiation therapy. PERFORMANCE: According to the literature NETs of the small bowel with a size over 3 cm can be detected with a sensitivity of 84.7% and a specificity of 96.6% using CT enteroclysis and MR enteroclysis provides the detection of NETs of the small bowel in 93.3% of cases. 'The sensitivity of MRI in detection of pancreatic NETs is between 74% and 100% and is, therefore, higher than CT. Detection of small primary tumors is carried out using PET-CT and seems to be the most sensitive imaging modality to identify the exact location. On the other hand MRI has to be regarded as the best imaging modality for detection of liver metastases compared to CT and PET-CT. ACHIEVEMENTS: The role of diagnostic imaging is to identify the exact location of the primary tumor and possible metastases, to define an appropriate therapy and to monitor treatment effects; however, the choice of the most appropriate diagnostic imaging modality varies depending on the location and type of the primary tumor. PRACTICAL RECOMMENDATIONS: The GEP-NETs are predominantly well-vascularized; therefore, dual-phase CT/MR imaging with the arterial and venous phases after contrast media injection is mandatory for detection and localization of primary tumors and metastases. For whole body staging CT and PET-CT should be performed.

[Importance of multidetector CT imaging in multiple trauma]. / Stellenwert der Multidetektor-CT bei Polytrauma.

CLINICAL/METHODICAL ISSUE: Diagnostic imaging of complex multiple trauma remains a challenge for any department providing modern emergency radiology (ER) service. An early and comprehensive approach for ER imaging is crucial for a priority-oriented and timely therapy concept with the aim of identifying potentially life-threatening injuries early and initiating appropriate treatment. STANDARD RADIOLOGICAL METHODS: The basic diagnostic approach still consists of focused ultrasound using focused assessment with sonography for trauma (FAST) and conventional radiography (CR), usually limited to a single supine chest x-ray for triaging patients undergoing immediate operations. METHODICAL INNOVATIONS: Multidetector computed tomography (MDCT) has become established as early whole body CT (WBCT) as the undisputable diagnostic method. The detection rate of injuries by WBCT is outstanding and it improves the probability of survival by 20-25% compared with all other previous methods. At the same time, the spatial and temporal resolution of MDCT was improved resulting in considerably shortened examination times but WBCT is still associated with a significant radiation exposure, even in the acute single use setting. Using modern scanner and dose reduction technology, including iterative reconstruction, a dose reduction of up to 40% could be achieved. The substantial number of images in WBCT is another challenge; images must be processed priority-oriented, read and transferred to the picture archiving and communications system (PACS). For rapid diagnosis, volume image reading (VIR) offers additional options to keep the diagnostic process on time. ACHIEVEMENTS/PRACTICAL RECOMMENDATIONS: Modern WBCT after multiple trauma is performed early, comprehensively and personalized so that WBCT improves the probability of survival by 20-25%.