Quantification of mechanical properties in long-term in vivo used silicone catheter lines according to DIN 10555-3.

BACKGROUND: Totally implantable central venous access port devices are crucial for intravenous application of chemotherapeutics and long-term therapy for chronic disease. Common complications include thrombosis and device fracture related to altered material properties through exposure in situ. This study exhibits whether uniaxial tensile properties (DIN 10555-3) of in vivo used catheters prove inferior to unused catheters. MATERIAL AND METHODS: 5 unused, originally packed silicone catheters were cut into 6 segments of 50 mm: 3 segments each were cleaned via cleaning solution (n = 15) while 3 segments were left unattended (n = 15). Distal segments (50 mm) of long-term in vivo used silicone catheters were cleaned before testing (n = 33). Overall mechanical behavior was tested in a custom-made self-centering, torsion free carrier. Maximum force stress at failure, strain at failure and Young's modulus were determined and statistically analyzed. FINDINGS: Unused catheters showed no significant difference in testing. in vivo used catheters exhibited 20% lower maximal force than unused catheters (p < 0.001), strain at break (p ã€ˆ0,001), and 7% higher elastic modulus (p = 0.004; power: 0.845). Due to a constant cross section area, stress at failure was proportional to maximum force (p < 0.001). Relation between determined parameters and dwell times was non-significant. INTERPRETATION: In vivo long-term used silicone catheters showed significantly lower ultimate strength than unused ones. It is likely that in situ altering changes the mechanical properties of catheters and may potentially lead to failure.

[Postmortem imaging of the lung in cases of COVID-19 deaths]. / Postmortale Bildgebung der Lunge bei COVID-19-Todesfällen.

CLINICAL/METHODOLOGICAL ISSUE: COVID-19 is a new viral disease that is associated with inflammatory pulmonary changes which can be detected in computed tomography (CT). So far postmortem CT (PMCT) has not been used as a screening instrument for the evaluation of deaths with and without autopsy. In this respect, its validity has to be proved in comparison to clinical-radiological experiences. STANDARD RADIOLOGICAL METHODS: Postmortem CT METHODICAL INNOVATIONS: So far, PMCT can be regarded as a methodological innovation that has not yet been sufficiently evaluated for pneumonia. PERFORMANCE: CT in clinical routine has a high sensitivity for pneumonia. However, to what extent postmortem artifacts are relevant to PMCT still has to be determined. ACHIEVEMENTS: There is still no standard procedure for the postmortem radiological diagnosis of COVID-19 disease. Despite postmortem artifacts, PMCT can provide valuable information about the presence of pneumonia with interstitial character, especially without autopsy. PRACTICAL RECOMMENDATIONS: PMCT is particularly useful in the assessment of suspected cases of COVID-19 pneumonia for morphological assessment in the context of monitoring deaths in the current pandemic situation.

Visualization of spatial and temporal temperature distributions with magnetic particle imaging for liver tumor ablation therapy.

Temperature-resolved magnetic particle imaging (MPI) represents a promising tool for medical imaging applications. In this study an approach based on a single calibration measurement was applied for highlighting the potential of MPI for monitoring of temperatures during thermal ablation of liver tumors. For this purpose, liver tissue and liver tumor phantoms embedding different superparamagnetic iron oxide nanoparticles (SPION) were prepared, locally heated up to 70 °C and recorded with MPI. Optimal temperature MPI SPIONs and a corresponding linear model for temperature calculation were determined. The temporal and spatial temperature distributions were compared with infrared (IR) camera results yielding quantitative agreements with a mean absolute deviation of 1 °C despite mismatches in boundary areas.

First magnetic particle imaging angiography in human-sized organs by employing a multimodal ex vivo pig kidney perfusion system.

OBJECTIVE: Magnetic particle imaging (MPI) is a new, fast 3D imaging technique, which is considered promising for angiographies. As available MPI scanners suffer from restricted spatial resolution and are mostly constructed for small animal imaging, no vessels within one organ have been depicted by MPI, yet. The purpose of this study was to develop an ex vivo organ perfusion system to display vessels within one organ of human size by MPI and to compare the results to an established 3D imaging technique. APPROACH: An ex vivo porcine kidney perfusion system compatible with digital subtraction angiography (DSA), magnetic resonance tomography and MPI was developed. DSA was used to exemplarily prove intact vessel structures under ex vivo perfusion in two organs. Perfusion in nine organs was displayed by the 3D imaging techniques magnetic resonance angiography (MRA) and MPI angiography. All visible vessels in MRA and MPI were counted and their number compared between both techniques. MAIN RESULTS: The ex vivo organ perfusion system allowed us to perform angiographies by DSA, MRA and MPI. With it, organs of human size could be imaged in small animal scanners, which permitted us to depict vessels within one organ by MPI for the first time. In comparison to MRA, 33% of all vessels were visible in MPI, a difference probably caused by restricted spatial resolution in MPI. SIGNIFICANCE: The presented ex vivo organ perfusion system can serve to practically evaluate MPI's potential for angiography in human-sized organs. This is especially relevant as long as available, for angiography-suited MPI scanners still suffer from size and spatial resolution restrictions.

[Recurrent vomiting and headaches in a 26-year-old male patient]. / Rezidivierendes Erbrechen und Kopfschmerzen bei einem 26-jährigen Patienten.

This article reports the case of a 26-year-old male patient with recurrent emesis and headache due to central nervous system tuberculosis. The thoracic computed tomography showed bilateral disseminated pulmonary micronodular infiltrates and a cavern connecting to the bronchial system. The cranial magnetic resonance imaging showed multiple supratentorial and infratentorial microabscesses with concomitant meningitis. Mycobacterium tuberculosis was detected in sputum, bronchoalveolar lavage and cerebrospinal fluid. The patient received first-line antituberculous drug treatment, including streptomycin (instead of ethambutol) and adjuvant prednisolone.

Test method for mechanical properties of implantable catheters according to DIN 10555-3.

To enable causal analysis of port catheter failure, this study aimed to develop an experimental setup for uniaxial tensile tests that addresses the specific requirements of highly elastic medical catheters; and to quantify parameters of the catheters' mechanical competence with respect to effects of artificial aging. Segments of 6F-polyurethane catheters were tested in their native status, after chemical and after mechanical aging. Tension experiments were performed with a rate of 220 mm/min until catheter failure. Material behavior was analyzed based on load cell measurements of the universal test system and an additional optical distance registration. The Young's modulus, the ultimate stress and the ultimate strain were determined. Chemical aging significantly decreased Young's modulus (84%; p = 0.001) and ultimate stress (83%; p < 0.001), whereas mechanical aged samples demonstrated similar results for the Young's modulus (p = 0.772) and a non-significant rise of ultimate stress (13%; p = 0.128). Ultimate strain did not differ significantly regardless of the pretreatment. The results proof reliability, reproducibility and sensitivity to quantify artificial aging induced variations and also promise to detect deviations in material features caused by long-term clinical usage of catheters.

Noise reduction angiographic imaging technology reduces radiation dose during bronchial artery embolization.

PURPOSE: Comparison of radiation doses in patients undergoing angiographic bronchial artery embolization (BAE) before and after a noise reduction imaging technology upgrade. METHODS: We performed a retrospective study of 70 patients undergoing BAE. Procedures were performed before (n=32) and after (n=38) the technology upgrade containing additional filters and improved image-processing. Cumulative air kerma (AK), cumulative dose area product (DAP), number of exposure frames, total fluoroscopy time and amount of contrast agent were recorded. Mean values were calculated and compared using two-tailed t-tests. DSA image quality was assessed independently by two blinded readers and compared using the Wilcoxon signed-rank test. RESULTS: Using the new technology resulted in a significant reduction of 59% in DAP (149.2 (103.1-279.1) vs. 54.8 (38.2-100.7) Gy*cm2, p<0.001) and a significant reduction of 60% for AK (1.3 (0.6-1.9) vs. 0.5 (0.3-0.9) Gy, p<0.001) in comparison to procedures before the upgrade. There was no significant difference between the number of exposure frames in both groups (251±181 vs. 254±133 frames, p=0.07), time of fluoroscopy (28.8 (18.5-50.4) vs. 28.1 (23.3-38.7) min, p=0.73), or the amount of contrast agent used (139.5±70.8 vs. 163.1±63.1ml, p=0.11). No significant difference regarding image quality could be detected (3 (2,3) vs. 3 (2-4), p=0.64). CONCLUSIONS: The new angiographic noise reduction technology significantly decreases the radiation dose during bronchial artery embolization without compromising image quality or increasing time of fluoroscopy or contrast volume.

In vivo liver visualizations with magnetic particle imaging based on the calibration measurement approach.

Magnetic particle imaging (MPI) facilitates the rapid determination of 3D in vivo magnetic nanoparticle distributions. In this work, liver MPI following intravenous injections of ferucarbotran (Resovist®) was studied. The image reconstruction was based on a calibration measurement, the so called system function. The application of an enhanced system function sample reflecting the particle mobility and aggregation status of ferucarbotran resulted in significantly improved image reconstructions. The finding was supported by characterizations of different ferucarbotran compositions with the magnetorelaxometry and magnetic particle spectroscopy technique. For instance, similar results were obtained between ferucarbotran embedded in freeze-dried mannitol sugar and liver tissue harvested after a ferucarbotran injection. In addition, the combination of multiple shifted measurement patches for a joint reconstruction of the MPI data enlarged the field of view and increased the covering of liver MPI on magnetic resonance images noticeably.

Endoscopic ultrasound-guided drainage of abdominal fluid collections after pancreatic surgery: Efficacy and long-term follow-up.

BACKGROUND/PURPOSE: Endoscopic ultrasound-guided drainage (EUS-GD) of postoperative abdominal fluid collections (POFC) following pancreatic surgery is used as an alternative or complement to percutaneous drainage (PD) procedure. The present single-center retrospective study evaluates its efficacy and safety. METHOD: We included consecutive cases with POFC treated by EUS-GD between September 2009 and November 2014 in our department. Technical success, long-term clinical success, recurrence rate and need for surgery were analyzed. RESULTS: 24 procedures in 20 patients (95 % after pancreatic resection) were assessed. Indications for surgery included tumors/lesions located in the pancreas (15/20), chronic pancreatitis (3/20) and duodenal adenoma not completely resectable endoscopically (2/20). EUS-GD was performed within a median of 30 days (IQR: 8.25) for a median fluid collection size of 72.5 mm (IQR: 46.25), requiring a mean of 1.2 sessions with placement of a mean of 2.1 plastic stents (7 Fr/10 Fr) per patient for a mean of 89 days (IQR: 127). Microbiology of aspirated fluid revealed positive cultures in 13 patients, mostly polymicrobial, isolated positive for fungal and 3 multidrug-resistant gram negative (MRGN) in 4 cases. An additional transpapillary drainage was inserted in 1/20 patients. 4/20 patients received PD, mostly before EUS-GD. Technical and clinical success was achieved in 20/20 (100 %) and 18/20 (90 %) patients, respectively, while 2 patients required re-operation. During follow-up (median 630 days after stent removal, range: 45 - 2160), recurrence occurred in 1/18 (5.5 %) patient that was referred for surgery. No death or severe adverse events were noted. CONCLUSION: EUS-GD is an effective, minimally invasive and safe method for therapy of POFC after pancreatic surgery offering long-term remission in about 95 % of cases.

Geometry planning and image registration in magnetic particle imaging using bimodal fiducial markers.

PURPOSE: Magnetic particle imaging (MPI) is a quantitative imaging modality that allows the distribution of superparamagnetic nanoparticles to be visualized. Compared to other imaging techniques like x-ray radiography, computed tomography (CT), and magnetic resonance imaging (MRI), MPI only provides a signal from the administered tracer, but no additional morphological information, which complicates geometry planning and the interpretation of MP images. The purpose of the authors' study was to develop bimodal fiducial markers that can be visualized by MPI and MRI in order to create MP-MR fusion images. METHODS: A certain arrangement of three bimodal fiducial markers was developed and used in a combined MRI/MPI phantom and also during in vivo experiments in order to investigate its suitability for geometry planning and image fusion. An algorithm for automated marker extraction in both MR and MP images and rigid registration was established. RESULTS: The developed bimodal fiducial markers can be visualized by MRI and MPI and allow for geometry planning as well as automated registration and fusion of MR-MP images. CONCLUSIONS: To date, exact positioning of the object to be imaged within the field of view (FOV) and the assignment of reconstructed MPI signals to corresponding morphological regions has been difficult. The developed bimodal fiducial markers and the automated image registration algorithm help to overcome these difficulties.

Increasing the sensitivity for stem cell monitoring in system-function based magnetic particle imaging.

The use of superparamagnetic iron oxide nanoparticles (SPIONs) has provided new possibilities in biophysics and biomedical imaging technologies. The magnetization dynamics of SPIONs, which can be influenced by the environment, are of central interest. In this work, different biological SPION environments are used to investigate three different calibration methods for stem cell monitoring in magnetic particle imaging. It is shown that calibrating using SPIONs immobilized via agarose gel or intracellular uptake results in superior stem cell image quality compared to mobile SPIONs in saline. This superior image quality enables more sensitive localization and identification of a significantly smaller number of magnetically labeled stem cells. The results are important for cell tracking and monitoring of future SPION based therapies such as hyperthermia based cancer therapies, targeted drug delivery, or tissue regeneration approaches where it is crucial to image a sufficiently small number of SPIONs interacting with biological matter.

Combined Preclinical Magnetic Particle Imaging and Magnetic Resonance Imaging: Initial Results in Mice.

PURPOSE: Magnetic particle imaging (MPI) is a new radiologic imaging modality. For the first time, a commercial preclinical scanner is installed. The goal of this study was to establish a workflow between MPI and magnetic resonance imaging (MRI) scanners for a complete in vivo examination of a mouse and to generate the first co-registered in vivo MR-MP images. MATERIALS AND METHODS: The in vivo examination of five mice were performed on a preclinical MPI scanner and a 7 Tesla preclinical MRI system. MRI measurements were used for anatomical referencing and validation of the injection of superparamagnetic iron oxide (SPIO) particles during a dynamic MPI scan. We extracted MPI data of the injection phase and co-registered it with MRI data. RESULTS: A workflow process for a combined in vivo MRI and MPI examination was established. A successful injection of ferucarbotran was proven in MPI and MRI. MR-MPI co-registration allocated the SPIOs in the inferior vena cava and the heart during and shortly after the injection. CONCLUSION: The acquisition of preclinical MPI and MRI data is feasible and allows the combined analysis of MR-MPI information.

Radiologic management of haemoptysis: diagnostic and interventional bronchial arterial embolisation.

UNLABELLED: Hemoptysis can be a life-threatening pulmonary emergency with high mortality, is symptomatic of an underlying severe pulmonary disease and requires immediate diagnosis and treatment. Diagnostically, bronchoscopy, conventional chest x-ray and contrast-enhanced multislice computed tomography (MSCT) with CT angiography (CTA) provide information regarding the underlying pulmonary disease, bleeding site, the vascular anatomy of the bronchial arteries (BA) and extrabronchial branches, as well a basis for planning of endovascular intervention. Therapeutically, bronchial artery embolization (BAE) is a safe and effective technique in the hands of an experienced interventionist with profound knowledge of the BA anatomy and possible pitfalls as well as experience with first-line therapy of recurrent and massive hemoptysis or as an intervention prior to elective surgery. Recurrent episodes of hemoptysis are not uncommon and require a prompt repeat BAE after exclusion of extrabronchial systemic and pulmonary artery bleeding sources. This review article should give an overview of the history, anatomical and pathophysiological basics and the clinical context of hemoptysis and diagnosis, as well as a survey of management, treatment and results of BAE. KEY POINTS: Hemoptyses are life threatening and require urgent diagnostic and therapy. Chest x-ray, bronchoscopy, and contrast-enhanced MSCT with CTA should be carried out before therapeutic bronchial artery embolization (BAE). BAE for the treatment of massive and recurrent hemoptysis is safe and effective. False embolization in spinal branches of BA are the most serious complication of a BAE. Repeatedly BAE refractory cases should undergo elective surgery.

Liver remnant regeneration in donors after living donor liver transplantation: long-term follow-up using CT and MR imaging.

PURPOSE: To assess liver remnant volume regeneration and maintenance, and complications in the long-time follow-up of donors after living donor liver transplantation using CT and MRI. MATERIALS AND METHODS: 47 donors with a mean age of 33.5 years who donated liver tissue for transplantation and who were available for follow-up imaging were included in this retrospective study. Contrast-enhanced CT and MR studies were acquired for routine follow-up. Two observers evaluated pre- and postoperative images regarding anatomy and pathological findings. Volumes were manually measured on contrast-enhanced images in the portal venous phase, and potential postoperative complications were documented. Pre- and postoperative liver volumes were compared for evaluating liver remnant regeneration. RESULTS: 47 preoperative and 89 follow-up studies covered a period of 22.4 months (range: 1 - 84). After right liver lobe (RLL) donation, the mean liver remnant volume was 522.0 ml (±â€Š144.0; 36.1 %; n = 18), after left lateral section (LLS) donation 1,121.7 ml (±â€Š212.8; 79.9 %; n = 24), and after left liver lobe (LLL) donation 1,181.5 ml (±â€Š279.5; 72.0 %; n = 5). Twelve months after donation, the liver remnant volume were 87.3 % (RLL; ±â€Š11.8; n = 11), 95.0 % (LS; ±â€Š11.6; n = 18), and 80.1 % (LLL; ±â€Š2.0; n = 2 LLL) of the preoperative total liver volume. Rapid initial regeneration and maintenance at 80 % of the preoperative liver volume were observed over the total follow-up period.  Minor postoperative complications were found early in 4 patients. No severe or late complications or mortality occurred. CONCLUSION: Rapid regeneration of liver remnant volumes in all donors and volume maintenance over the long-term follow-up period of up to 84 months without severe or late complications are important observations for assessing the safety of LDLT donors. KEY POINTS: Liver remnant volumes of LDLT donors rapidly regenerated after donation and volumes were maintained over the long-term follow-up period of up to 84 months without severe or late complications.

Superparamagnetic iron oxide nanoparticles in biomedicine: applications and developments in diagnostics and therapy.

Superparamagnetic iron oxide nanoparticles (SPIO) can be used to image physiological processes and anatomical, cellular and molecular changes in diseases. The clinical applications range from the imaging of tumors and metastases in the liver, spleen and bone marrow, the imaging of lymph nodes and the CNS, MRA and perfusion imaging to atherosclerotic plaque and thrombosis imaging. New experimental approaches in molecular imaging describe undirected SPIO trapping (passive targeting) in inflammation, tumors and associated macrophages as well as the directed accumulation of SPIO ligands (active targeting) in tumor endothelia and tumor cells, areas of apoptosis, infarction, inflammation and degeneration in cardiovascular and neurological diseases, in atherosclerotic plaques or thrombi. The labeling of stem or immune cells allows the visualization of cell therapies or transplant rejections. The coupling of SPIO to ligands, radio- and/or chemotherapeutics, embedding in carrier systems or activatable smart sensor probes and their externally controlled focusing (physical targeting) enable molecular tumor therapies or the imaging of metabolic and enzymatic processes. Monodisperse SPIO with defined physicochemical and pharmacodynamic properties may improve SPIO-based MRI in the future and as targeted probes in diagnostic magnetic resonance (DMR) using chip-based µNMR may significantly expand the spectrum of in vitro analysis methods for biomarker, pathogens and tumor cells. Magnetic particle imaging (MPI) as a new imaging modality offers new applications for SPIO in cardiovascular, oncological, cellular and molecular diagnostics and therapy.

Quantitative assessment of bone marrow attenuation values at MDCT: an objective tool for the detection of bone bruise related to occult sacral insufficiency fractures.

OBJECTIVES: To prove the feasibility of using Hounsfield attenuation values at MDCT to detect bone bruises related to sacral insufficiency fractures. METHODS: Twenty-two patients with acute sacrum trauma and no fracture findings at MDCT were included in our prospective study. Two observers independently reviewed CTs regarding visual signs of bone bruises in 132 defined regions of the sacral alae. Interobserver agreement was tested by κ statistics. Subsequently, HU values were obtained in the same regions, and attenuation differences between the two sides were calculated. Validity and reliability were assessed by intraclass correlation coefficient and Bland-Altman analysis. HU differences were subjected to ROC curve analysis to determine sensitivity, specificity, PPV and NPV. MRI served as standard reference. RESULTS: MRI revealed 19 regions with bone bruises and associated sacral insufficiency fractures. HU measurements demonstrated good validity and reliability (r = 0.989). ROC curve analysis exhibited an ideal cutoff value of 35.7 HU density difference between affected and non-affected regions. Visual evaluation revealed moderate agreement (κ = 0.48); diagnostic accuracy was inferior to objective evaluation. CONCLUSIONS: Assessment of differences in bone marrow density by HU measurements is an objective and reliable tool for detection of bone bruises associated with occult sacral insufficiency fractures. KEY POINTS : • Bone bruising is associated with occult sacral insufficiency fractures. • Assessment of differences in bone marrow CT attenuation appears valid and reliable. • Comparative HU measurements of bone marrow allow detection of bone bruises. • Comparative HU measurements have high specificity and negative predictive values. • Comparative HU measurements may make further diagnostic workup with MRI unnecessary.

[Skeletal and dermatological manifestations of the nevoid Basal cell carcinoma syndrome (Gorlin-Goltz syndrome). Results of 8 patients in 12 years]. / Skelettale und kutane Charakteristika des nävoiden Basalzellkarzinomsyndroms (Gorlin-Goltz-Syndrom). Ergebnisse von 8 Patienten aus 12 Jahren.

PURPOSE: In 1960 Gorlin and Goltz defined the nevoid basal cell carcinoma syndrome (NBCCS, Gorlin-Goltz Syndrome) as a syndrome comprising multiple basal cell carcinoma, odontogenic keratocysts, and skeletal anomalies. NBCCS is an autosomal dominantly inherited disease with an estimated prevalence of 1:150,000 and diagnosis of this syndrome is often an accidental finding of radiological investigations. The purpose of this study was to report the varied radiological and dermatological manifestations of our patients affected with NBCCS and to present this rare syndrome as a differential diagnosis of skeletal anomalies. MATERIALS AND METHODS: Between 1994 and 2005 the demographic, clinical, radiological and histological data of 8 patients with NBCCS were retrospectively analyzed. Nevoid basal cell carcinoma syndrome was diagnosed in the event of two major or one major and two minor criteria. The major criteria are more than 2 basal cell carcinoma, odontogenic keratocysts, three or more palmar pits, and calcification of the falx cerebri. RESULTS: Between 1994 and 2005 8 patients (3 females and 5 males) with NBCCS were treated in our departments. The average age at the time of diagnosis of NBCCS was 49.9 years. All patients had a minimum of two major criteria. The major criteria with the most frequency were the basal cell carcinoma (6 patients) and the odontogenic keratocysts (5 patients), followed by the calcification of the falx cerebri and palmoplantar pits (4 patients). There was no gender-related or age-related predilection and only one patient was affected with pain in his fingers which radiologically correlated to small cystic bone lesions ("flame-shaped lucencies"). CONCLUSION: Due to limitations in identification of mutations in the PTCH1 gene, clinical and radiological examination still remains a very important factor in the treatment of patients suffering from NBCCS. The knowledge of the varied skeletal manifestations and constellations is therefore essential and correlates with therapeutic consequences. Often chest, rib, spine, skull, and jaw X-rays show the way. Due to the risk of the development of an associated medulloblastoma, neurological surveillance in 6-month intervals in addition to an annual MRI of the cerebrum up to an age of 7 is strongly recommended.