Vascular 3D Printing with a Novel Biological Tissue Mimicking Resin for Patient-Specific Procedure Simulations in Interventional Radiology: a Feasibility Study.

Three-dimensional (3D) printing of vascular structures is of special interest for procedure simulations in Interventional Radiology, but remains due to the complexity of the vascular system and the lack of biological tissue mimicking 3D printing materials a technical challenge. In this study, the technical feasibility, accuracy, and usability of a recently introduced silicone-like resin were evaluated for endovascular procedure simulations and technically compared to a commonly used standard clear resin. Fifty-four vascular models based on twenty-seven consecutive embolization cases were fabricated from preinterventional CT scans and each model was checked for printing success and accuracy by CT-scanning and digital comparison to its original CT data. Median deltas (Δ) of luminal diameters were 0.35 mm for clear and 0.32 mm for flexible resin (216 measurements in total) with no significant differences (p > 0.05). Printing success was 85.2% for standard clear and 81.5% for the novel flexible resin. In conclusion, vascular 3D printing with silicone-like flexible resin was technically feasible and highly accurate. This is the first and largest consecutive case series of 3D-printed embolizations with a novel biological tissue mimicking material and is a promising next step in patient-specific procedure simulations in Interventional Radiology.

Complication rates of percutaneous brachial artery puncture: effect of live ultrasound guidance.

PURPOSE: The current literature on the use of brachial artery access is controversial. Some studies found increased puncture site complications. Others found no higher complication rates than in patients with femoral or radial access. The purpose of this study was to determine the impact of ultrasound (US)-guidance on access site complications. MATERIALS AND METHODS: This is a single-center retrospective study of all consecutive patients with brachial arterial access for interventional procedures. Complications were classified into minor complications (conservative treatment only) and major complications (requiring surgical intervention). The brachial artery was cannulated in the antecubital fossa under US-guidance. After the intervention, manual compression or closure devices, both followed by a compression bandage for 3 h, either achieved hemostasis. RESULTS: Seventy-five procedures in seventy-one patients were performed in the study period using brachial access. Access was successful in all cases (100%). Procedures in different vascular territories were performed: neurovascular (10/13.5%), upper extremity (32/43.2%), visceral (20/27.0%), and lower extremity (12/16.3%). Sheath size ranged from 3.2F to 8F (mean: 5F). Closure devices were used in 17 cases (22.7%). In total, six complications were observed (8.0%), four minor complications (5.3%, mostly puncture site hematomas), and two major complications, that needed surgical treatment (2.7%). No brachial artery thrombosis or upper extremity ischemia occurred. CONCLUSION: Exclusive use of US-guidance resulted in a low risk of brachial artery access site complications in our study compared to the literature. US-guidance has been proven to reduce the risk of access site complications in several studies in femoral access. In addition, brachial artery access yields a high technical success rate and requires no additional injection of spasmolytic medication. Sheath size was the single significant predictor for complications.

A double crystal von Hamos spectrometer for traceable x-ray emission spectroscopy.

A novel double full-cylinder crystal x-ray spectrometer for x-ray emission spectroscopy (XES) has been realized based on a modified von Hamos geometry. The spectrometer is characterized by its compact dimensions, its versatility with respect to the number of crystals used in series in the detection path, and the option to perform calibrated XES measurements. The full-cylinder crystals used are based on highly annealed pyrolytic graphite with a thickness of 40 µm, which was bent to a radius of curvature of 50 mm. The flexible design of the spectrometer allows for an easy change-within the same setup-between measurements with one crystal for maximized efficiency or two crystals for increased spectral resolving power. The spectrometer realized can be used at different end-stations of synchrotron radiation beamlines or can be laboratory-based. The main application focus of the spectrometer is the determination of x-ray fundamental atomic parameters in the photon energy range from 2.4 to 18 keV. The evaluation of chemical speciation is also an area of application, as demonstrated in the example of battery electrodes using resonant inelastic x-ray scattering.

[Passive and active magnetic resonance cholangiopancreatography : Technique, indications, and typical anatomy]. / Passive und aktive Magnetresonanz-Cholangiopankreatikographie : Technik, Indikation und typische Anatomie.

CLINICAL/METHODICAL ISSUE: In daily routine, every radiologist is confronted with a variety of questions concerning the biliary tract and pancreatic system. STANDARD RADIOLOGICAL METHODS: Today, besides sonography, magnetic resonance cholangiopancreatography (MRCP) is considered the method of choice in the investigation of many disorders of the hepatobiliary and pancreatic system and is commonly preferred over invasive ERCP in a mere diagnostic setting. METHODICAL INNOVATIONS: Since its introduction in 1991, MRCP has constantly evolved. Major innovations have been the reduction of acquisition time by using fast spin echo (FSE) sequences, the use of respiratory gating and contrast-enhanced imaging of the bile ducts with hepatobiliary-specific MRI contrast agents. PERFORMANCE: Many diagnoses may already be made with noncontrast enhanced images. By supplemental administration of a hepatobiliary-specific contrast agent, it is also possible to evaluate the flow dynamics of the bile. This is of additional value especially in patients who underwent surgery of the biliodigestive system or endoscopic interventions. ACHIEVEMENTS: Aside from robustness and reproducibility, a major advantage of this technique is the modular design of imaging protocols, which can easily be adapted to the clinical question. PRACTICAL RECOMMENDATIONS: MRCP is a reliable and low-risk imaging method for primary diagnosis and follow-up of biliary and pancreatic pathologies.

ESGAR consensus statement on liver MR imaging and clinical use of liver-specific contrast agents.

OBJECTIVES: To develop a consensus and provide updated recommendations on liver MR imaging and the clinical use of liver-specific contrast agents. METHODS: The European Society of Gastrointestinal and Abdominal Radiology (ESGAR) formed a multinational European panel of experts, selected on the basis of a literature review and their leadership in the field of liver MR imaging. A modified Delphi process was adopted to draft a list of statements. Descriptive and Cronbach's statistics were used to rate levels of agreement and internal reliability of the consensus. RESULTS: Three Delphi rounds were conducted and 76 statements composed on MR technique (n = 17), clinical application of liver-specific contrast agents in benign, focal liver lesions (n = 7), malignant liver lesions in non-cirrhotic (n = 9) and in cirrhotic patients (n = 18), diffuse and vascular liver diseases (n = 12), and bile ducts (n = 13). The overall mean score of agreement was 4.84 (SD ±0.17). Full consensus was reached in 22 % of all statements in all working groups, with no full consensus reached on diffuse and vascular diseases. CONCLUSIONS: The consensus provided updated recommendations on the methodology, and clinical indications, of MRI with liver specific contrast agents in the study of liver diseases. KEY POINTS: • Liver-specific contrast agents are recommended in MRI of the liver. • The hepatobiliary phase improves the detection and characterization of hepatocellular lesions. • Liver-specific contrast agents can improve the detection of HCC.

Safety of Radioembolization with (90)Yttrium Resin Microspheres Depending on Coiling or No-Coiling of Aberrant/High-Risk Vessels.

PURPOSE: To evaluate the safety of radioembolization (RE) with (90)Yttrium ((90)Y) resin microspheres depending on coiling or no-coiling of aberrant/high-risk vessels. MATERIALS AND METHODS: Early and late toxicity after 566 RE procedures were analyzed retrospectively in accordance with the National Cancer Institute's Common Terminology Criteria for Adverse Events (CTCAE v3.0). For optimal safety, aberrant vessels were either coil embolized (n = 240/566, coiling group) or a more peripheral position of the catheter tip was chosen to treat right or left liver lobes (n = 326/566, no-coiling group). RESULTS: Clinically relevant late toxicities (≥ Grade 3) were observed in 1% of our overall cohort. The no-coiling group had significantly less "any" (P = 0.0001) or "clinically relevant" (P = 0.0003) early toxicity. There was no significant difference (P > 0.05) in delayed toxicity in the coiling versus the no-coiling group. No RE-induced liver disease was noted after all 566 procedures. CONCLUSION: RE with (90)Y resin microspheres is a safe and effective treatment option. Performing RE without coil embolization of aberrant vessels prior to treatment could be an alternative for experienced centers.

[Rational imaging of hepatocellular carcinoma. The challenge of multimodal diagnostic criteria]. / Rationale Schnittbildgebung des hepatozellulären Karzinoms. Die Herausforderung multimodaler Diagnosekriterien.

CLINICAL/METHODICAL ISSUE: Both computed tomography (CT) and magnetic resonance imaging (MRI) constitute the gold standard in radiological imaging of hepatocellular carcinoma (HCC). In cases of typical contrast behavior each modality as a single dynamic technique allows the diagnosis of HCC. There is still a challenge in detection of small HCCs < 2 cm, in differentiating HCC and high-grade dysplasia from other benign liver lesions as well as the evaluation of hypovascular liver lesions in the cirrhotic liver. PERFORMANCE: Nowadays, both modalities achieve high detection rates of 90-100 % for lesions > 2 cm. Regarding lesions between 1 and 2 cm there is a higher sensitivity for MRI ranging between 80 and 90 % compared to 60-75 % with CT. Besides the multimodal diagnostic criteria, MRI provides significant benefits with the use of hepatobiliary contrast. Especially in combination with diffusion- weighted imaging (DWI) increased sensitivity and diagnostic accuracy compared to CT has been described for lesions sized < 2 cm. Regarding the differentiation from other hepatic nodules in the cirrhotic liver there is strong evidence that the coexistence of arterial enhancement and hypointensity on hepatobiliary imaging is specific for HCC. Moreover, hypointensity on hepatobiliary imaging is associated with a high positive predictive value (PPV) of up to 100 % for the presence of high-grade dysplasia and HCC. ACHIEVEMENTS: The use of MRI including hepatobiliary imaging and DWI has to be regarded as the best non-invasive imaging modality for the detection of HCC and for the characterization of nodules in patients with liver cirrhosis. In comparison to CT there are benefits regarding detection of small lesions < 2 cm and evaluation of hypovascular liver lesions in the context of the hepatocarcinogenesis including prognostic values of premalignant lesions. PRACTICAL RECOMMENDATIONS: Both MRI and CT provide a high diagnostic performance in evaluation of HCC in liver cirrhosis. With MRI there are considerable advantages regarding the detection rate and specificity. For daily clinical routine, CT offers a fast, reliable and easy available modality with benefits for patients in reduced general state of health and restricted compliance.

Randomized multicentre trial of gadoxetic acid-enhanced MRI versus conventional MRI or CT in the staging of colorectal cancer liver metastases.

BACKGROUND: This multicentre international randomized trial compared the impact of gadoxetic acid-enhanced magnetic resonance imaging (MRI), MRI with extracellular contrast medium (ECCM-MRI) and contrast-enhanced computed tomography (CE-CT) as a first-line imaging method in patients with suspected colorectal cancer liver metastases (CRCLM). METHODS: Between October 2008 and September 2010, patients with suspected CRCLM were randomized to one of the three imaging modalities. The primary endpoint was the proportion of patients for whom further imaging after initial imaging was required for a confident diagnosis. Secondary variables included confidence in the therapeutic decision, intraoperative deviations from the initial imaging-based surgical plan as a result of additional operative findings, and diagnostic efficacy of the imaging modalities versus intraoperative and pathological extent of the disease. RESULTS: A total of 360 patients were enrolled. Efficacy was analysed in 342 patients (118, 112 and 112 with gadoxetic acid-enhanced MRI, ECCM-MRI and CE-CT respectively as the initial imaging procedure). Further imaging was required in 0 of 118, 19 (17.0 per cent) of 112 and 44 (39.3 per cent) of 112 patients respectively (P < 0.001). Diagnostic confidence was high or very high in 98.3 per cent of patients for gadoxetic acid-enhanced MRI, 85.7 per cent for ECCM-MRI and 65.2 per cent for CE-CT. Surgical plans were changed during surgery in 28, 32 and 47 per cent of patients in the respective groups. CONCLUSION: The diagnostic performance of gadoxetic acid-enhanced MRI was better than that of CE-CT and ECCM-MRI as the initial imaging modality. No further imaging was needed in the gadoxetic acid-enhanced MRI group and comparison of diagnostic efficacy parameters demonstrated the diagnostic superiority of gadoxetic acid-enhanced MRI. REGISTRATION NUMBER: NCT00764621(http://clinicaltrials.gov); EudraCT number: 2008-000583-16 (https://eudract.ema.europa.eu/).

Fra-2/AP-1 controls adipocyte differentiation and survival by regulating PPARγ and hypoxia.

Adipocyte cell number is a crucial factor for controlling of body weight and metabolic function. The regulation of adipocyte numbers in the adult organism is not fully understood but is considered to depend on the homeostasis of cell differentiation and apoptosis. Herein, we show that targeted deletion of the activator protein (AP-1)-related transcription factor Fra-2 in adipocytes in vivo (Fra-2(Δadip) mice) induces a high-turnover phenotype with increased differentiation and apoptosis of adipocytes, leading to a decrease in body weight and fat pad mass. Importantly, adipocyte cell numbers were significantly reduced in Fra-2(Δadip) mice. At the molecular level, Fra-2 directly binds to the PPARγ2 promoter and represses PPARγ2 expression. Deletion of Fra-2 leads to increased PPARγ2 expression and adipocyte differentiation as well as increased adipocyte apoptosis through upregulation of hypoxia-inducible factors (HIFs). These findings suggest that Fra-2 is an important checkpoint to control adipocyte turnover. Therefore, inhibition of Fra-2 may emerge as a useful strategy to increase adipocyte turnover and to reduce adipocyte numbers and fat mass in the body.

Radioembolization as locoregional therapy of hepatic metastases in uveal melanoma patients.

PURPOSE: To retrospectively evaluate the overall survival, safety, and efficacy of metastatic uveal melanoma patients after radioembolization as salvage therapy. MATERIALS AND METHODS: Thirteen patients were treated with radioembolization of branches of the hepatic artery with resin-based yttrium-90 ((90)Y)-labelled microspheres. Twelve patients underwent a single application, and 1 patient underwent 4 interventions. Dosages from 644 to 2,450 MBq (mean activity 1,780) were applied. Treatment response was evaluated by way of liver magnetic resonance imaging and computed tomography (CT) as well as whole-body fluorodeoxyglucose positron emission tomography (PET)/CT with evaluation of percentage changes in SUV(max) before and at 2-3 months after therapy. Kaplan-Meier analysis was calculated to determine overall survival. RESULTS: Partial remission (PR) was observed in 8 (62 %), stable disease (SD) in 2 (15 %), and progressive disease (PD) in 3 (23 %) patients under terms of standard criteria and PR in 3 (23 %), SD in 3 (23 %), and PD in 7 (54 %) patients according to PET criteria. Neither RECIST nor PET criteria showed a significant difference in predicting overall survival (P = 0.12 and 0.11, respectively). Median survival time after radioembolization was 7 months. No acute toxicity with in-hospital morbidity was observed. One patient developed hepatomegaly, and 1 patient developed gastric ulceration. Throughout follow-up, progression of extrahepatic metastases was observed. CONCLUSION: Radioembolization may be a promising therapy in uveal melanoma patients with predominant hepatic metastases. At first follow-up, we observed PR or SD in 77 % patients under terms of standard criteria with an acceptable toxicity profile.

[Value of magnetic resonance imaging in diffuse liver diseases]. / Stellenwert der MRT bei diffusen Lebererkrankungen.

CLINICAL PROBLEM: Diffuse liver diseases show an increasing prevalence. The diagnostic gold standard of liver biopsy has several disadvantages. There is a clinical demand for non-invasive imaging-based techniques to qualitatively and quantitatively evaluate the entire liver. STANDARD RADIOLOGICAL METHODS: Ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI) are routinely used. METHODICAL INNOVATIONS: Steatosis: chemical shift and frequency selective imaging, MR spectroscopy (MRS). Hemochromatosis: MR-based iron quantification. Fibrosis: MR elastography, diffusion, intravoxel incoherent motion (IVIM) and MR perfusion. PERFORMANCE/ACHIEVEMENTS/PRACTICAL RECOMMENDATIONS: T1-weighted in and opposed phase imaging is the clinically most frequently used MR technique to noninvasively detect and quantify steatosis. New methods for quantification that are not influenced by confounders like iron overload are under investigation. The most sensitive method to measure the fat content of the liver is MRS. As data acquisition and analysis remain complex and there is no whole organ coverage, MRS of the liver is not a routine method. With an optimized protocol incorporating T2* sequences, MRI is the modality of choice to quantify iron overload in hemochromatosis. Standard MR sequences cannot depict early stages of liver fibrosis. Advanced MR techniques (e.g. elastography, diffusion, IVIM and perfusion) for noninvasive assessment of liver fibrosis appear promising but their role has to be further investigated.

[Practical implementation of a quality management system in a radiological department]. / Praktische Umsetzung von Qualitätsmanagement in einer radiologischen Abteilung.

This article describes the architecture of a project aiming to implement a DIN EN ISO 9001 quality management system in a radiological department. It is intended to be a practical guide to demonstrate each step of the project leading to certification of the system. In a planning phase resources for the implementation of the project have to be identified and a quality management (QM) group as core team has to be formed. In the first project phase all available documents have to be checked and compiled in the QM manual. Moreover all relevant processes of the department have to be described in so-called process descriptions. In a second step responsibilities for the project are identified. Customer and employee surveys have to be carried out and a nonconformity management system has to be implemented. In this phase internal audits are also needed to check the new QM system, which is finally tested in the external certification audit with reference to its conformity with the standards.

[Diffusion-weighted magnetic resonance imaging of the abdomen]. / Diffusionsgewichtete Magnetresonanztomographie des Abdomens.

Diffusion-weighted magnetic resonance imaging (DW-MRI) provides qualitative and quantitative information of tissue cellularity and the integrity of cellular membranes. Since DW-MRI can be performed without ionizing radiation exposure and contrast media application, DW-MRI is a particularly attractive tool for patients with allergies for gadolinium-based contrast agents or renal failure. Recent technical developments have made DW-MRI a robust and feasible technique for abdominal imaging. DW-MRI provides information on the detection and characterization of focal liver lesions and can also visualize treatment effects and early changes in chronic liver disease. In addition DW-MRI is a promising tool for the detection of inflammatory changes in patients with Crohn's disease.

[Diagnosis and multimodal therapy for hepatocellular carcinoma]. / Diagnose und multimodale Therapie des hepatozellulären Karzinoms.

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death in the world. The majority of HCCs develops on the basis of a chronic liver disease. This often complicates diagnosis and therapy. Non-invasive diagnostic criteria are based on dynamic imaging techniques and the serum level of AFP (alpha-fetoprotein). When evaluating HCC patients for therapy, besides tumor burden and localisation, the therapeutic evaluation must also consider the general condition of the patient and his/her liver function. For this purpose, the BCLC algorithm of the Barcelona Clinic for Liver Disease has proven helpful. Only one-third of the patients can be cured by resection, transplantation or local tumour ablation. In locally advanced cases transarterial procedures including transarterial chemoembolisation and radioembolisation are applied. HCC is a chemo-resistant tumour and chemotherapy is not accepted as standard of care in HCC. Sorafenib is the first systemic treatment with proven efficacy approved for the treatment of advanced and metastatic HCC. Interdisciplinary management of HCC patients is essential in order to provide every patient with the optimal therapy at his specific stage of disease.