187 results on '"Daniel A. Rüfenacht"'
Search Results
2. Change in aneurysmal flow pulsatility after flow diverter treatment.
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Ignacio Larrabide, Arjan J. Geers, Hernán G. Morales, Philippe Bijlenga, and Daniel A. Rüfenacht
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- 2016
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3. Spatial Stabilization Strategies Applied to Multiphysics Modeling of Blood Clotting Using a Modified PTT Model.
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Julien Egger, Ajit S. Mallik, Dominik Szczerba, Daniel A. Rüfenacht, Gábor Székely, and Sven Hirsch
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- 2013
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4. Outlook for Grid Service technologies within the @neurIST eHealth environment.
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Antonio Arbona, Siegfried Benkner, Jochen Fingberg, Alejandro F. Frangi, M. Hofmann, D. Rodney Hose, Guy Lonsdale, Daniel A. Rüfenacht, and Marco Viceconti
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- 2006
5. Lattice Boltzmann Analysis of the Flow Reduction Mechanism in Stented Cerebral Aneurysms for the Endovascular Treatment.
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Miki Hirabayashi, Makoto Ohta, Daniel A. Rüfenacht, and Bastien Chopard
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- 2003
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6. Fast virtual deployment of self-expandable stents: Method and in vitro evaluation for intracranial aneurysmal stenting.
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Ignacio Larrabide, Minsuok Kim, Luca Augsburger, Maria-Cruz Villa-Uriol, Daniel A. Rüfenacht, and Alejandro F. Frangi
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- 2012
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7. The Role of Computational Fluid Dynamics in the Management of Unruptured Intracranial Aneurysms: A Clinicians' View.
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Pankaj Kumar Singh 0001, Alberto Marzo, Stuart C. Coley, Guntram Berti, Philippe Bijlenga, Patricia V. Lawford, Maria-Cruz Villa-Uriol, Daniel A. Rüfenacht, Keith M. McCormack, Alejandro F. Frangi, Umang J. Patel, and D. Rodney Hose
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- 2009
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8. Light transport in tissue by 3D Monte Carlo: Influence of boundary voxelization.
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Tiziano Binzoni, T. S. Leung, R. Giust, Daniel A. Rüfenacht, and Amir Gandjbakhche
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- 2008
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9. Thrombosis modeling in intracranial aneurysms: a lattice Boltzmann numerical algorithm.
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Rafik Ouared, Bastien Chopard, Bernd Stahl, Daniel A. Rüfenacht, Hasan Yilmaz, and Guy Courbebaisse
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- 2008
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10. A lattice Boltzmann simulation of clotting in stented aneursysms and comparison with velocity or shear rate reductions.
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Bastien Chopard, Rafik Ouared, and Daniel A. Rüfenacht
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- 2006
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11. Numerical analysis of the flow pattern in stented aneurysms and its relation to velocity reduction and stent efficiency.
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Miki Hirabayashi, Makoto Ohta, Krisztina Baráth, Daniel A. Rüfenacht, and Bastien Chopard
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- 2006
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12. A lattice Boltzmann study of blood flow in stented aneurism.
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Miki Hirabayashi, Makoto Ohta, Daniel A. Rüfenacht, and Bastien Chopard
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- 2004
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13. Giant intracranial aneurysms of the posterior circulation and their relation to the brainstem: analysis of risk factors for neurological deficits
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Nils Ole Schmidt, Daniel A. Rüfenacht, Adisa Kursumovic, Bujung Hong, Jan-Karl Burkhardt, Julius Dengler, Philippe Bijlenga, Christian Hohaus, Peter Vajkoczy, Nicolai Maldaner, and Pavlina Lenga
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Male ,medicine.medical_specialty ,Databases, Factual ,Cohort Studies ,Aneurysm ,Risk Factors ,Internal medicine ,medicine ,Humans ,In patient ,Prospective Studies ,Aged ,business.industry ,Intracranial Aneurysm ,General Medicine ,Middle Aged ,medicine.disease ,Hydrocephalus ,Cardiology ,Female ,Brainstem ,Nervous System Diseases ,Mr images ,Evans index ,business ,Motor Deficit ,Partial thrombosis ,Brain Stem - Abstract
OBJECTIVEGiant posterior circulation aneurysms (GPCirAs) usually cause substantial mass effect on the brainstem, which may lead to neurological deficits. So far, there has been no systematic investigation of factors associated with such deficits in GPCirA. The authors aim to examine the risk factors for cranial nerve deficit (CND), motor deficit, and disability in patients with GPCirA.METHODSUsing MR images obtained in 30 patients with unruptured GPCirA, the authors examined GPCirA volume, presence of hydrocephalus or partial thrombosis (PT) of the aneurysm, and the degree of brainstem displacement measured by the distance between the McRae line and the tip of the GPCirA (∆MT). They evaluated associations between these factors and neurological deficits.RESULTSThirty GPCirAs in 30 patients were included. The prevalence of CNDs was 50%. Patients with CNDs significantly differed from those without CNDs in terms of age (mean 51.0 years [SD 15.0 years] vs 69.0 years [SD 21.0 years], p = 0.01) and in ∆MT (median 50.7 mm [IQR 39.2–53.9 mm] vs 39.0 mm [IQR 32.3–45.9 mm], p = 0.02). The prevalence of motor deficits was 33.3%. Patients with motor deficits showed a larger ∆MT (median 50.5 mm [IQR 40.8–54.6 mm]) compared with those without (∆MT: median 39.1 mm [IQR 32.8–50.5 mm], p = 0.04). GPCirA volume was larger in patients with poor modified Rankin Scale (mRS) scores (median 14.9 cm3 [IQR 8.6–18.7 cm3]) than in those with mRS scores of 0–2 (median 6.8 cm3 [IQR 4.4–11.7 cm3], p = 0.03). After adjusting for patient age and the occurrence of hydrocephalus or PT, the authors found that higher degrees of disability were significantly associated with aneurysm volume (OR 1.13, 95% CI 1.0–1.3; p = 0.04), but not with ∆MT. The occurrence of CND or motor deficit was not associated with any of the examined variables. There was no correlation between GPCirA volume and ∆MT (rs = 0.01, p = 0.96). The prevalence of neurological deficits did not differ between GPCirA at the basilar apex, the basilar trunk, the vertebrobasilar junction, or the vertebral artery.CONCLUSIONSIn this study, the neurological condition of the patients was associated only with GPCirA volume and not with the degree of brainstem displacement, the occurrence of PT or hydrocephalus, or the exact location of the GPCirA. These findings highlight the clinical relevance of GPCirA volume and suggest that factors such as brainstem displacement or PT should play less of a role when finding arguments for or against treatment of GPCirA.Clinical trial registration no.: NCT02066493 (clinicaltrials.gov)
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- 2019
14. Three- to five-dimensional biomedical multisensor imaging for the assessment of neurological (dys)function.
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Luc M. Bidaut, Roberto D. Pascual-Marqui, Jacqueline Delavelle, Alain Naimi, Margitta Seeck, Christophe Michel, Daniel Slosman, Osman Ratib, Daniel A. Rüfenacht, Theodor Landis, Nicolas de Tribolet, Jean-Raoul Scherrer, and François Terrier
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- 1996
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15. Shape irregularity of the intracranial aneurysm lumen exhibits diagnostic value
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Daniel A. Rüfenacht, Philippe Bijlenga, Norman Juchler, Sven Hirsch, Sandrine Morel, Sabine Schilling, Vartan Kurtcuoglu, University of Zurich, Juchler, Norman, and Hirsch, Sven
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Adult ,Male ,medicine.medical_specialty ,Disease status ,Lumen (anatomy) ,610 Medicine & health ,ddc:616.07 ,Aneurysm, Ruptured ,616: Innere Medizin und Krankheiten ,030218 nuclear medicine & medical imaging ,10052 Institute of Physiology ,Aneurysm rupture ,03 medical and health sciences ,0302 clinical medicine ,Aneurysm ,Patient age ,Irregularity ,Quantitative morphology ,medicine ,Humans ,10064 Neuroscience Center Zurich ,Neuroradiology ,Aged ,business.industry ,Smoking ,Intracranial Aneurysm ,Middle Aged ,medicine.disease ,Rating study ,ddc:616.8 ,2746 Surgery ,Cerebral Angiography ,2728 Neurology (clinical) ,Rough surface ,10076 Center for Integrative Human Physiology ,Hypertension ,570 Life sciences ,biology ,Surgery ,Female ,Neurology (clinical) ,Radiology ,Continuous parameter ,business ,030217 neurology & neurosurgery - Abstract
Erworben im Rahmen der Schweizer Nationallizenzen (http://www.nationallizenzen.ch), Background: Morphological irregularity is linked to intracranial aneurysm wall instability and manifests in the lumen shape. Yet there is currently no consent on how to assess shape irregularity. The aims of this work are to quantify irregularity as perceived by clinicians, to break down irregularity into morphological attributes, and to relate these to clinically relevant factors such as rupture status, aneurysm location, and patient age or sex. Methods: Thirteen clinicians and 26 laypersons assessed 134 aneurysm lumen segmentations in terms of overall perceived irregularity and five different morphological attributes (presence/absence of a rough surface, blebs, lobules, asymmetry, complex geometry of the parent vasculature). We examined rater agreement and compared the ratings with clinical factors by means of regression analysis or binary classification. Results: Using rank-based aggregation, the irregularity ratings of clinicians and laypersons did not differ statistically. Perceived irregularity showed good agreement with curvature (coefficient of determination R2 = 0.68 ± 0.08) and was modeled very accurately using the five morphological rating attributes plus shape elongation (R2 = 0.95 ± 0.02). In agreement with previous studies, irregularity was associated with aneurysm rupture status (AUC = 0.81 ± 0.08); adding aneurysm location as an explanatory variable increased the AUC to 0.87 ± 0.09. Besides irregularity, perceived asymmetry, presence of blebs or lobules, aneurysm size, non-sphericity, and curvature were linked to rupture. No association was found between morphology and any of patient sex, age, and history of smoking or hypertension. Aneurysm size was linked to morphology. Conclusions: Irregular lumen shape carries significant information on the aneurysm’s disease status. Irregularity constitutes a continuous parameter that shows a strong association with the rupture status. To improve the objectivity of morphological assessment, we suggest examining shape through six different morphological attributes, which can characterize irregularity accurately.
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- 2020
16. Cranial nerve deficits in giant cavernous carotid aneurysms and their relation to aneurysm morphology and location
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Maria Teresa Pedro, Philippe Bijlenga, Dorothee Mielke, Peter Vajkoczy, M Piano, Joachim K. Krauss, Nicolai Maldaner, Susanne Guhl, G Durner, Christian Hohaus, Edoardo Boccardi, Pavlina Lenga, N Etminan, Jan-Karl Burkhardt, Daniel Hänggi, Julius Dengler, Daniel A. Rüfenacht, and Jens Lehmberg
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Adult ,Male ,medicine.medical_specialty ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,Aneurysm ,Humans ,Medicine ,Aged ,Neuroradiology ,medicine.diagnostic_test ,business.industry ,Cranial nerves ,Cranial Nerves ,Angiography, Digital Subtraction ,Intracranial Aneurysm ,Magnetic resonance imaging ,Interventional radiology ,Odds ratio ,Digital subtraction angiography ,Middle Aged ,medicine.disease ,Magnetic Resonance Imaging ,Thrombosis ,Female ,Surgery ,Neurology (clinical) ,Radiology ,business ,Carotid Artery, Internal ,030217 neurology & neurosurgery - Abstract
Giant cavernous carotid aneurysms (GCCAs) usually exert substantial mass effect on adjacent intracavernous cranial nerves. Since predictors of cranial nerve deficits (CNDs) in patients with GCCA are unknown, we designed a study to identify associations between CND and GCCA morphology and the location of mass effect. This study was based on data from the prospective clinical and imaging databases of the Giant Intracranial Aneurysm Registry. We used magnetic resonance imaging and digital subtraction angiography to examine GCCA volume, presence of partial thrombosis (PT), GCCA origins, and the location of mass effect. We also documented whether CND was present. We included 36 GCCA in 34 patients, which had been entered into the registry by eight participating centers between January 2009 and March 2016. The prevalence of CND was 69.4%, with one CND in 41.7% and more than one in 27.5%. The prevalence of PT was 33.3%. The aneurysm origin was most frequently located at the anterior genu (52.8%). The prevalence of CND did not differ between aneurysm origins (p = 0.29). Intracavernous mass effect was lateral in 58.3%, mixed medial/lateral in 27.8%, and purely medial in 13.9%. CND occurred significantly more often in GCCA with lateral (81.0%) or mixed medial/lateral (70.0%) mass effect than in GCCA with medial mass effect (20.0%; p = 0.03). After adjusting our data for the effects of the location of mass effect, we found no association between the prevalence of CND and aneurysm volume (odds ratio (OR) 1.30 (0.98–1.71); p = 0.07), the occurrence of PT (OR 0.64 (0.07–5.73); p = 0.69), or patient age (OR 1.02 (95% CI 0.95–1.09); p = 0.59). Distinguishing between medial versus lateral location of mass effect may be more helpful than measuring aneurysm volumes or examining aneurysm thrombosis in understanding why some patients with GCCA present with CND while others do not. NCT02066493 ( clinicaltrials.gov )
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- 2018
17. Model-based blood flow quantification from DSA: quantitative evaluation on patient data and comparison with TCCD.
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Irina Wächter-Stehle, Alexandra Groth, Tom Bruijns, Olivier Brina, Daniel A. Rüfenacht, Zsolt Kulcsar, Vitor Mendes Pereira, Fabienne Perren, David J. Hawkes, and Jürgen Weese
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- 2012
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18. Clinical study of model-based blood flow quantification on cerebrovascular data.
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Alexandra Groth, Irina Wächter-Stehle, Olivier Brina, Fabienne Perren, Vitor Mendes Pereira, Daniel A. Rüfenacht, Tom Bruijns, Matthias Bertram, and Jürgen Weese
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- 2011
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19. Diffusion-weighted and perfusion-weighted magnetic resonance imaging of the prostate gland of healthy adult dogs
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Florian Willmitzer, Adriano Wang-Leandro, Patrick R Kircher, Daniel A. Rüfenacht, Beat Porcellini, Francesca Del Chicca, Dagmar Verdino, Henning Richter, Peter W Kronen, University of Zurich, and Willmitzer, Florian
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Male ,040301 veterinary sciences ,3400 General Veterinary ,610 Medicine & health ,0403 veterinary science ,Dogs ,Parenchyma ,Medicine ,Effective diffusion coefficient ,Animals ,Humans ,Clinical significance ,General Veterinary ,business.industry ,0402 animal and dairy science ,Prostate ,04 agricultural and veterinary sciences ,General Medicine ,Anatomy ,Perfusion-Weighted Magnetic Resonance Imaging ,040201 dairy & animal science ,Peripheral ,Perfusion ,medicine.anatomical_structure ,Diffusion Magnetic Resonance Imaging ,11404 Department of Clinical Diagnostics and Services ,Abdomen ,Prostate gland ,business ,Magnetic Resonance Angiography - Abstract
OBJECTIVE To describe diffusion and perfusion characteristics of the prostate gland of healthy sexually intact adult dogs as determined by use of diffusion-weighted and perfusion-weighted MRI. ANIMALS 12 healthy sexually intact adult Beagles. PROCEDURES Ultrasonography of the prostate gland was performed. Subsequently, each dog was anesthetized, and morphological, diffusion-weighted, and perfusion-weighted MRI of the caudal aspect of the abdomen was performed. The apparent diffusion coefficient was calculated for the prostate gland parenchyma in diffusion-weighted MRI images in the central ventral and peripheral dorsal areas. Perfusion variables were examined in multiple regions of interest (ROIs) in the ventral and dorsal areas of the prostate gland and in the gluteal musculature. Signal intensity was determined, and a time-intensity curve was generated for each ROI. RESULTS Results of ultrasonographic examination of the prostate gland revealed no abnormalities for any dog. Median apparent diffusion coefficient of the prostate gland was 1.51 × 10−3 mm2/s (range, 1.04 × 10−3 mm2/s to 1.86 × 10−3 mm2/s). Perfusion-weighted MRI variables for the ROIs differed between the prostate gland parenchyma and gluteal musculature. CONCLUSIONS AND CLINICAL RELEVANCE Results provided baseline information about diffusion and perfusion characteristics of the prostate gland in healthy sexually intact adult dogs. Additional studies with dogs of various ages and breeds, with and without abnormalities of the prostate gland, will be necessary to validate these findings and investigate clinical applications.
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- 2019
20. Clinical implications and radiographic characteristics of the relation between giant intracranial aneurysms of the posterior circulation and the brainstem
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Daniel A. Rüfenacht, Peter Vajkoczy, Pavlina Lenga, Nicolai Maldaner, Julius Dengler, N. O. Schmidt, Jan-Karl Burkhardt, Julien Haemmerli, Philippe Bijlenga, Adisa Kursumovic, and Bujung Hong
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Adult ,Male ,medicine.medical_specialty ,Neurology ,Intracranial Aneurysm/diagnostic imaging/pathology/therapy ,Brain Stem/diagnostic imaging/pathology ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,Aneurysm ,Modified Rankin Scale ,otorhinolaryngologic diseases ,medicine ,Humans ,Prospective cohort study ,Neuroradiology ,Aged ,medicine.diagnostic_test ,business.industry ,Interventional radiology ,Intracranial Aneurysm ,Middle Aged ,medicine.disease ,ddc:616.8 ,Treatment Outcome ,Surgery ,Female ,Neurology (clinical) ,Neurosurgery ,Brainstem ,Radiology ,business ,030217 neurology & neurosurgery ,Brain Stem - Abstract
Giant intracranial aneurysms of the posterior circulation (GPCirA) are rare entities compressing the brainstem and adjacent structures. Previous evidence has shown that the amount of brainstem shift away from the cranial base is not associated with neurological deficits. This raises the question whether other factors may be associated with neurological deficits. All data were extracted from the Giant Intracranial Aneurysm Registry, an international multicenter prospective study on giant intracranial aneurysms. We grouped GPCirA according to the mass effect on the brainstem (lateral versus medial). Brainstem compression was evaluated with two indices: (a) brainstem compression ratio (BCR) or diameter of the compressed brainstem to the assumed normal diameter of the brainstem and (b) aneurysm to brainstem ratio (ABR) or diameter of the aneurysm to the diameter of the compressed brainstem. We examined associations between neurological deficits and GPCirA characteristics using binary regression analysis. Twenty-eight GPCirA were included. Twenty GPCirA showed medial (71.4%) and 8 lateral compression of the brainstem (28.6%). Baseline characteristics did not differ between the groups for patient age, aneurysm diameter, aneurysm volume, modified Rankin Scale (mRS), motor deficit (MD), or cranial nerve deficits (CND). Mean BCR was 53.0 in the medial and 54.0 in the lateral group (p = 0.92). The mean ABR was 2.9 in the medial and 2.3 in the lateral group (p = 0.96). In the entire cohort, neither BCR nor ABR nor GPCirA volumes were associated with the occurrence of CND or MD. In contrast, disability (mRS) was significantly associated with ABR (OR 1.94 (95% CI 1.01–3.70; p = 0.045) and GPCirA volumes (OR 1.21 (95% CI 1.01–1.44); p = 0.035), but not with BCR. In this cohort of patients with GPCirA, neither the degree of lateral projection nor the amount of brainstem compression predicted neurological deficits. Disability was associated only with aneurysm volume. When designing treatment strategies for GPCirA, aneurysm laterality or the amount of brainstem compression should be viewed as less relevant while the high risk of rupture of such giant lesions should be emphasized. The registry is listed at clinicaltrials.gov under the registration no. NCT02066493.
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- 2019
21. MRI-guided, transrectal, intraprostatic steam application as potential focal therapeutic modality for prostatic diseases in a large animal translational model: A feasibility follow-up study
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Adriano Wang-Leandro, Emile Hiltbrand, Florian Willmitzer, Agnieszka Karol, Beat Porcellini, Daniel A. Rüfenacht, Patrick R Kircher, Henning Richter, Peter W Kronen, University of Zurich, Celik, Haydar, and Wang-Leandro, Adriano
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Ablation Techniques ,Male ,Prostatic Diseases ,Biopsy ,030232 urology & nephrology ,Pathology and Laboratory Medicine ,Diagnostic Radiology ,Prostate cancer ,0302 clinical medicine ,Ultrasound Imaging ,Medicine and Health Sciences ,Immune Response ,Mammals ,Multidisciplinary ,medicine.diagnostic_test ,Radiology and Imaging ,Prostate Cancer ,Prostate ,Prostate Diseases ,Eukaryota ,Pain scale ,Magnetic Resonance Imaging ,10226 Department of Molecular Mechanisms of Disease ,Coagulative necrosis ,Oncology ,030220 oncology & carcinogenesis ,Vertebrates ,11404 Department of Clinical Diagnostics and Services ,Chronic inflammatory response ,Medicine ,Radiology ,Anatomy ,Research Article ,medicine.medical_specialty ,Imaging Techniques ,Urology ,Science ,Immunology ,Surgical and Invasive Medical Procedures ,610 Medicine & health ,Research and Analysis Methods ,Necrosis ,03 medical and health sciences ,Dogs ,Exocrine Glands ,Signs and Symptoms ,Diagnostic Medicine ,medicine ,Animals ,Inflammation ,1000 Multidisciplinary ,business.industry ,Organisms ,Prostatic Neoplasms ,Biology and Life Sciences ,Cancers and Neoplasms ,Magnetic resonance imaging ,medicine.disease ,Steam ,Genitourinary Tract Tumors ,Amniotes ,Feasibility Studies ,Prostate Gland ,Prostate surgery ,business - Abstract
Parallel to establishment of diagnostic surveillance protocols for detection of prostatic diseases, novel treatment strategies should be developed. The aim of the present study is to evaluate the feasibility and possible side effects of transrectal, MRI-targeted intraprostatic steam application in dogs as an established large animal translational model for prostatic diseases in humans. Twelve healthy experimental, intact, male beagle dogs without evidence of prostatic pathology were recruited. An initial MRI examination was performed, and MRI-targeted steam was applied intraprostatically immediately thereafter. Serum levels of C-reactive protein (CRP), clinical and ultrasonographic examinations were performed periodically following the procedure to assess treatment effect. Four weeks after treatment, all dogs underwent follow-up MRI examinations and three needle-core biopsies were obtained from each prostatic lobe. Descriptive statistics were performed. MRI-guided intraprostatic steam application was successfully performed in the study population. The first day after steam application, 7/12 dogs had minimal signs of discomfort (grade 1/24 evaluated with the short-form Glasgow Composite Measure Pain Scale) and no dogs showed any sign of discomfort by day 6. CRP elevations were detected in 9/12 dogs during the first week post steam application. Mild to moderate T2 hyperintense intraparenchymal lesions were identified during follow-up MRI in 11/12 dogs four weeks post procedure. Ten of these lesions enhanced mild to moderately after contrast administration. Coagulative necrosis or associated chronic inflammatory response was detected in 80.6% (58/72) of the samples obtained. MRI-targeted intraprostatic steam application is a feasible technique and displays minimal side effects in healthy dogs as translational model for human prostatic diseases. This opens the possibility of minimally invasive novel treatment strategies for intraprostatic lesions.
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- 2019
22. Effect of Flow Diverter Porosity on Intraaneurysmal Blood Flow
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Luca Augsburger, Nikos Stergiopulos, Mohamed Farhat, Edouard Fonck, Daniel A. Rüfenacht, Zsolt Kulcsar, and Philippe Reymond
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medicine.medical_specialty ,Pulsatile flow ,Prosthesis Design ,Blood vessel prosthesis ,medicine ,Humans ,Computer Simulation ,Radiology, Nuclear Medicine and imaging ,Porosity ,business.industry ,Models, Cardiovascular ,Intracranial Aneurysm ,Mechanics ,Blood flow ,Vorticity ,Blood Vessel Prosthesis ,Surgery ,Equipment Failure Analysis ,Flow conditions ,Particle image velocimetry ,Flow (mathematics) ,Computer-Aided Design ,Stents ,Neurology (clinical) ,business ,Blood Flow Velocity - Abstract
Background and Purpose: : Growth and rupture, the two events that dominate the evolution of an intracranial aneurysm, are both dependent on intraaneurysmal flow. Decrease of intraaneurysmal flow is considered an attractive alternative for treating intracranial aneurysms by minimally invasive techniques. Such modification can be achieved by inserting stents or flow diverters alone. In the present paper, the effect of different commercial and innovative flow diverters' porosity was studied in intracranial aneurysm models. Material and Methods: : Single and stent-in-stent combination of Neuroform II as well as single and stent-in-stent combination of a new innovative, low-porosity, intracranial stent device (D1, D2, D1 + D2) were inserted in models of intracranial aneurysms under shear-driven flow and inertia-driven flow configurations. Steady and pulsating flow rates were applied using a blood-like fluid. Particle image velocimetry was used to measure velocity vector fields in the aneurysm midplane along the vessel axis. Flow and vorticity patterns, velocity and vorticity magnitudes were quantified and their value compared with the same flows in absence of the flow diverter. Results: : In absence of flow diverters, a solid-like rotation could be observed in both shear-driven and inertia-driven models under steady and pulsatile flow conditions. The flow effects due to the insertion of low-porous devices such as D1 or D2 provoked a complete alteration of the flow patterns and massive reduction of velocity or vorticity magnitudes, whereas the introduction of clinically adopted high-porous devices provoked less effect in the aneurysm cavity. As expected, results showed that the lower the porosity the larger the reduction in velocity and vorticity within the aneurysm cavity. The lowest-porosity device combination (D1 and D2) reached an averaged reduction of flow parameters of 80% and 88% under steady and pulsatile flow conditions, respectively. The reduction in mean velocity and vorticity was much more significant in the shear-driven flows as compared to the inertia-driven flows. Conclusion: : Although device porosity is the main parameter influencing flow reduction, other parameters such as device design and local flow conditions may influence the level of flow reduction within intracranial aneurysms
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- 2018
23. Radiation dose in vertebroplasty
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S. G. Wetzel, Daniel A. Rüfenacht, Hasan Yilmaz, Alexis Kelekis, K. E. Wilhelm, German Abdo, A. Mehdizade, Karl-Olof Lövblad, Jean-Baptiste Martin, J. M. Viera, and T. Somon
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Male ,Health Personnel ,Pain ,Radiation Dosage ,Radiography, Interventional ,Injections ,fashion ,Medicine ,Humans ,Pain Management ,Radiology, Nuclear Medicine and imaging ,Absorbed Radiation Dose ,Aged ,Dosimeter ,Spinal Neoplasms ,business.industry ,Radiation dose ,Palliative Care ,Bone Cements ,Hand ,Spine ,fashion.garment ,Fluoroscopy ,Lead apron ,Female ,Neurology (clinical) ,Cardiology and Cardiovascular Medicine ,business ,Nuclear medicine - Abstract
We wished to measure the absorbed radiation dose during fluoroscopically controlled vertebroplasty and to assess the possibility of deterministic radiation effects to the operator. The dose was measured in 11 consecutive procedures using thermoluminescent ring dosimeters on the hand of the operator and electronic dosimeters inside and outside of the operator's lead apron. We found doses of 0.022-3.256 mGy outside and 0.01-0.47 mGy inside the lead apron. Doses on the hand were higher, 0.5-8.5 mGy. This preliminary study indicates greater exposure to the operator's hands than expected from traditional apron measurements.
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- 2018
24. Flow diversion treatment: intra-aneurismal blood flow velocity and WSS reduction are parameters to predict aneurysm thrombosis
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Philippe Reymond, Ajit S. Mallik, John Millar, Luca Augsburger, Sven Hirsch, Isabel Wanke, Daniel A. Rüfenacht, Zsolt Kulcsar, Stephan G. Wetzel, Vitor Mendes Pereira, University of Zurich, and Kulcsár, Zsolt
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Adult ,Male ,medicine.medical_specialty ,medicine.medical_treatment ,Medizin ,Hemodynamics ,610 Medicine & health ,Computational fluid dynamics ,Wall shear stress ,Aneurysm ,Predictive Value of Tests ,Humans ,Medicine ,cardiovascular diseases ,skin and connective tissue diseases ,Reduction (orthopedic surgery) ,Cerebral aneurysm ,Aged ,Neuroradiology ,Flow diversion ,Flow diverter ,Thrombosis ,medicine.diagnostic_test ,business.industry ,Intracranial Aneurysm ,Interventional radiology ,Blood flow ,Middle Aged ,medicine.disease ,10020 Clinic for Cardiac Surgery ,2746 Surgery ,Cerebral Angiography ,10022 Division of Surgical Research ,2728 Neurology (clinical) ,cardiovascular system ,Female ,Surgery ,sense organs ,Neurology (clinical) ,Radiology ,business ,human activities ,Blood Flow Velocity ,Carotid Artery, Internal ,Follow-Up Studies - Abstract
Acta Neurochirurgica, 154 (10), ISSN:0001-6268, ISSN:0942-0940
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- 2018
25. In vivo visualization and analysis of 3-D hemodynamics in cerebral aneurysms with flow-sensitized 4-D MR imaging at 3T
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Aurélien F. Stalder, Stephan Meckel, Stephan G. Wetzel, Michael Markl, Francesco Santini, Daniel A. Rüfenacht, and Ernst W. Radü
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medicine.medical_specialty ,Hemodynamics ,Magnetic resonance angiography ,Aneurysm ,Imaging, Three-Dimensional ,In vivo ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,cardiovascular diseases ,Neuroradiology ,medicine.diagnostic_test ,business.industry ,Reproducibility of Results ,Intracranial Aneurysm ,Blood flow ,Middle Aged ,medicine.disease ,Mr imaging ,Cerebrovascular Circulation ,Cerebral Angiography ,cardiovascular system ,Feasibility Studies ,Female ,Vascular Resistance ,Neurology (clinical) ,Radiology ,Cardiology and Cardiovascular Medicine ,Nuclear medicine ,business ,Blood Flow Velocity ,Magnetic Resonance Angiography - Abstract
Introduction: Blood-flow patterns and wall shear stress (WSS) are considered to play a major role in the development and rupture of cerebral aneurysms. These hemodynamic aspects have been extensively studied in vitro using geometric realistic aneurysm models. The purpose of this study was to evaluate the feasibility of in vivo flow-sensitized 4-D MR imaging for analysis of intraaneurysmal hemodynamics. Methods: Five cerebral aneurysms were examined using ECG-gated, flow-sensitized 4-D MR imaging at 3T in three patients. Postprocessing included quantification of flow velocities, visualization of time-resolved 2-D vector graphs and 3-D particle traces, vortical flow analysis, and estimation of WSS. Flow patterns were analyzed in relation to aneurysm geometry and aspect ratio. Results: Magnitude, spatial and temporal evolution of vortical flow differed markedly among the aneurysms. Particularly unstable vortical flow was demonstrated in a wide-necked parophthalmic ICA aneurysm (high aspect ratio). Relatively stable vortical flow was observed in aneurysms with a lower aspect ratio. Except for a wide-necked cavernous ICA aneurysm (low aspect ratio), WSS was reduced in all aneurysms and showed a high spatial variation. Conclusion: In vivo flow-sensitized 4-D MR imaging can be applied to analyze complex patterns of intraaneurysmal flow. Flow patterns, distribution of flow velocities, and WSS seem to be determined by the vascular geometry of the aneurysm. Temporal and spatial averaging effects are drawbacks of the MR-based analysis of flow patterns as well as the estimation of WSS, particularly in small aneurysms. Further studies are needed to establish a direct link between definitive flow patterns and different aneurysm geometries
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- 2018
26. CT angiography, MR angiography and rotational digital subtraction angiography for volumetric assessment of intracranial aneurysms. An experimental study
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Daniel A. Rüfenacht, Luc Bidaut, Jacques Moret, M. Muster, Michel Piotin, Shinya Mandai, and Philippe Gailloud
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medicine.medical_specialty ,Ultrasonography, Doppler, Transcranial ,Contrast Media ,Image subtraction ,Magnetic resonance angiography ,Aneurysm ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,cardiovascular diseases ,Neuroradiology ,Observer Variation ,medicine.diagnostic_test ,business.industry ,Angiography, Digital Subtraction ,Intracranial Aneurysm ,Digital subtraction angiography ,medicine.disease ,Cerebrovascular Circulation ,Postmortem Changes ,Pulsatile Flow ,Angiography ,cardiovascular system ,Neurology (clinical) ,Radiology ,Tomography ,Cardiology and Cardiovascular Medicine ,business ,Tomography, X-Ray Computed ,Carotid Artery, Internal ,Magnetic Resonance Angiography ,Cerebral angiography - Abstract
The purpose of our experimental study was to assess the accuracy and precision of CT angiography (CTA), MR angiography (MRA) and rotational digital subtraction angiography (DSA) for measuring the volume of an in vitro aneurysm model. A rigid model of the anterior cerebral circulation harbouring an anterior communicating aneurysm was connected to a pulsatile circuit. It was studied using unenhanced 3D time-of-flight MRA, contrast-enhanced CTA and rotational DSA angiography. The source images were then postprocessed on dedicated workstations to calculate the volume of the aneurysm. CTA was more accurate than MRA (P=0.0019). Rotational DSA was more accurate than CTA, although the difference did not reach statistical significance (P=0.1605), and significantly more accurate than MRA (P
- Published
- 2018
27. Multisociety Consensus Quality Improvement Revised Consensus Statement for Endovascular Therapy of Acute Ischemic Stroke: From the American Association of Neurological Surgeons (AANS), American Society of Neuroradiology (ASNR), Cardiovascular and Interventional Radiology Society of Europe (CIRSE), Canadian Interventional Radiology Association (CIRA), Congress of Neurological Surgeons (CNS), European Society of Minimally Invasive Neurological Therapy (ESMINT), European Society of Neuroradiology (ESNR), European Stroke Organization (ESO), Society for Cardiovascular Angiography and Interventions (SCAI), Society of Interventional Radiology (SIR), Society of NeuroInterventional Surgery (SNIS), and World Stroke Organization (WSO)
- Author
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David, Sacks, Blaise, Baxter, Bruce C V, Campbell, Jeffrey S, Carpenter, Christophe, Cognard, Diederik, Dippel, Muneer, Eesa, Urs, Fischer, Klaus, Hausegger, Joshua A, Hirsch, Muhammad Shazam, Hussain, Olav, Jansen, Mahesh V, Jayaraman, Alexander A, Khalessi, Bryan W, Kluck, Sean, Lavine, Philip M, Meyers, Stephen, Ramee, Daniel A, Rüfenacht, Clemens M, Schirmer, and Dierk, Vorwerk
- Subjects
Stroke ,Endovascular Procedures ,Humans ,Radiography, Interventional ,610 Medicine & health ,Quality Improvement ,Brain Ischemia ,Time-to-Treatment - Published
- 2018
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28. PHASES Score for the Management of Intracranial Aneurysm: A Cross-Sectional Population-Based Retrospective Study
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Sabine Schilling, Renato Gondar, Fabienne Perren, Marco Vincenzo Corniola, Karl Lothard Schaller, Johanna Cuony, Philippe Bijlenga, Sven Hirsch, Daniel A. Rüfenacht, and Sandrine Morel
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Adult ,Male ,Subarachnoid hemorrhage ,Population based ,Multidisciplinary team ,Severity of Illness Index ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,Aneurysm ,Risk Factors ,Medicine ,Humans ,Prospective Studies ,Aged ,Retrospective Studies ,Advanced and Specialized Nursing ,business.industry ,Disease Management ,Retrospective cohort study ,Intracranial Aneurysm ,Middle Aged ,medicine.disease ,Cross-Sectional Studies ,Population Surveillance ,Female ,Neurology (clinical) ,Medical emergency ,Cardiology and Cardiovascular Medicine ,business ,030217 neurology & neurosurgery - Abstract
Background and Purpose— The aim of this study is to assess whether the PHASES score allows to (1) match decisions taken by multidisciplinary team whether to observe or intervene, (2) classify patients being diagnosed with a ruptured versus unruptured intracranial aneurysm (UIA), and (3) discriminate patients at low risk of rupture from the population of patients diagnosed with intracranial aneurysm. Methods— Population-based prospective and consecutive data were collected between 2006 and 2014. Patients (n=841) were stratified into 4 groups: stable UIA; growing observed UIA; immediately treated UIA; and aneurysmal subarachnoid hemorrhage (aSAH). All patients initially observed were pooled in a follow-up UIA group; patients from growing observed UIA, immediately treated UIA, and aSAH were pooled in a high risk of rupture group. Results are expressed as median [quartile 1, quartile 3]. Results— PHASES scores of immediately treated UIA patients were significantly higher than follow-up UIA group (5 [3, 7] versus 2 [1, 4]). Patients diagnosed with UIA and PHASES score of >3 were more likely to be treated, and the score ≤3 was predictive for observation (areas under these curves=0.74). Odds of being diagnosed with an aSAH were associated with PHASES score of >3 (UIA, 4 [2, 6]; aSAH, 5 [4, 8]; areas under these curves=0.66). Scores of stable UIA patients were significantly lower than high risk of rupture group (2 [1, 4] versus 5 [4, 7]; stable UIA outcome prediction by PHASES score of ≤3: areas under these curves=0.76). Conclusions— There is a progression of PHASES score between stable UIA, growing observed UIA, immediately treated UIA, and aSAH groups. PHASES score of ≤3 is associated with a low but not negligible likelihood of aneurysm rupture, and specificity of the classifier is low.
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- 2017
29. Neuroradiologie et neurochirurgie: Anévrisme intracrânien de découverte fortuite
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Daniel A. Rüfenacht, Philippe Bijlenga, and Isabel Wanke
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- 2017
30. Neuroradiologie und Neurochirurgie: Zufallsbefund intrakranielles Aneurysma
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Isabel Wanke, Philippe Bijlenga, and Daniel A. Rüfenacht
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business.industry ,Medicine ,business - Published
- 2017
31. Multidisciplinary Consensus on Assessment of Unruptured Intracranial Aneurysms
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Seppo Juvela, Timo Koivisto, Julian Spears, Michael T. Lawton, J Mocco, Daniel Hänggi, David Hasan, Isabel Wanke, Peter D. LeRoux, Colin P. Derdeyn, John H. Wong, Nima Etminan, Yuichi Murayama, Daniel L. Barrow, Kentaro Mori, Shinji Nagahiro, Andreas Raabe, Gabriel J.E. Rinkel, Joshua B. Bederson, Hans Jakob Steiger, Daniel A. Rüfenacht, Edward W. Mee, Cameron G. McDougall, Peter J. Kirkpatrick, Alberto Pasqualin, Robert Brown, George K.C. Wong, Andrew J. Molyneux, Peter Vajkoczy, Giuseppe Lanzino, Volker Seifert, Jean Raymond, E. Sander Connolly, Kerim Beseoglu, Akio Morita, R. Loch Macdonald, Helmuth Steinmetz, James C. Torner, Neville W. Knuckey, Hidetoshi Kasuya, Michael Kerin Morgan, Clinicum, and Department of Neurosciences
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Adult ,medicine.medical_specialty ,Subarachnoid hemorrhage ,education ,Population ,Medizin ,Delphi method ,3124 Neurology and psychiatry ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,Aneurysm ,RUPTURE ,LESS-THAN-7 MM YES ,Multidisciplinary approach ,Delphi technique ,therapeutics ,Humans ,Medicine ,Family history ,Psychiatry ,SUBARACHNOID HEMORRHAGE ,METAANALYSIS ,POPULATION ,Advanced and Specialized Nursing ,education.field_of_study ,business.industry ,Intracranial Aneurysm ,NATURAL-HISTORY ,CEREBRAL ANEURYSMS ,medicine.disease ,3. Good health ,incidental aneurysm ,Natural history ,cerebral aneurysm ,consensus ,natural history ,ENDOVASCULAR TREATMENT ,Emergency medicine ,Life expectancy ,Neurology (clinical) ,TIME TRENDS ,Cardiology and Cardiovascular Medicine ,business ,EMPHASIS ,030217 neurology & neurosurgery - Abstract
Background and Purpose— To address the increasing need to counsel patients about treatment indications for unruptured intracranial aneurysms (UIA), we endeavored to develop a consensus on assessment of UIAs among a group of specialists from diverse fields involved in research and treatment of UIAs. Methods— After composition of the research group, a Delphi consensus was initiated to identify and rate all features, which may be relevant to assess UIAs and their treatment by using ranking scales and analysis of inter-rater agreement (IRA) for each factor. IRA was categorized as very high, high, moderate, or low. Results— Ultimately, 39 specialists from 4 specialties agreed (high or very high IRAs) on the following key factors for or against UIA treatment decisions: (1) patient age, life expectancy, and comorbid diseases; (2) previous subarachnoid hemorrhage from a different aneurysm, family history for UIA or subarachnoid hemorrhage, nicotine use; (3) UIA size, location, and lobulation; (4) UIA growth or de novo formation on serial imaging; (5) clinical symptoms (cranial nerve deficit, mass effect, and thromboembolic events from UIAs); and (6) risk factors for UIA treatment (patient age and life expectancy, UIA size, and estimated risk of treatment). However, IRAs for features rated with low relevance were also generally low, which underlined the existing controversy about the natural history of UIAs. Conclusions— Our results highlight that neurovascular specialists currently consider many features as important when evaluating UIAs but also highlight that the appreciation of natural history of UIAs remains uncertain, even within a group of highly informed individuals.
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- 2014
32. Pulssynchroner Tinnitus – radiologische Diagnostik und Therapie
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Isabel Wanke, Daniel A. Rüfenacht, and Michael Forsting
- Abstract
Ein pulssynchroner Tinnitus zeichnet sich durch ein rhythmisches Gerausch aus, das vom Patienten im Ohr wahrgenommen wird und dem Pulsschlag angepasst ist. Anders als beim klassischen Dauerpfeifton im Ohr lassen sich beim pulssynchronen Tinnitus oft krankhafte, vaskulare Ursachen in der Bildgebung feststellen. Dieser Beitrag soll zeigen, welche Ursachen es gibt, wie man sie darstellt und klar machen, dass es gefahrliche Ursachen fur ein pulssynchrones Ohrgerausch gibt, die behandelt werden mussen.
- Published
- 2014
33. Plea for an international Aneurysm Data Bank: description and perspectives
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Sandrine Morel, Philippe Bijlenga, Sven Hirsch, Karl Lothard Schaller, and Daniel A. Rüfenacht
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Databases, Factual ,Computer science ,International Cooperation ,Data management ,0206 medical engineering ,005: Computerprogrammierung, Programme und Daten ,02 engineering and technology ,Disease ,ddc:616.07 ,computer.software_genre ,616: Innere Medizin und Krankheiten ,03 medical and health sciences ,0302 clinical medicine ,Multidisciplinary approach ,Database, factual ,Humans ,Computer Simulation ,Information Dissemination ,business.industry ,Information technology ,Intracranial Aneurysm ,General Medicine ,020601 biomedical engineering ,ddc:616.8 ,Data sharing ,Disease modeling ,Risk analysis (engineering) ,Information model ,Epidemiological Monitoring ,Data integration ,Surgery ,Neurology (clinical) ,Personalized medicine ,business ,computer ,030217 neurology & neurosurgery ,Human - Abstract
The disease resulting in the formation, growth, and rupture of intracranial aneurysms is complex. Research is accumulating evidence that the disease is driven by many different factors, some constant and others variable over time. Combinations of factors may induce specific biophysical reactions at different stages of the disease. A better understanding of the biophysical mechanisms responsible for the disease initiation and progression is essential to predict the natural history of the disease. More accurate predictions are mandatory to adequately balance risks between observation and intervention at the individual level as expected in the age of personalized medicine. Multidisciplinary exploration of the disease also opens an avenue to the discovery of possible preventive actions or medical treatments. Modern information technologies and data processing methods offer tools to address such complex challenges requiring 1) the collection of a high volume of information provided globally, 2) integration and harmonization of the information, and 3) management of data sharing with a broad spectrum of stakeholders.Over the last decade an infrastructure has been set up and is now made available to the academic community to support and promote exploration of intracranial disease, modeling, and clinical management simulation and monitoring.The background and purpose of the infrastructure is reviewed. The infrastructure data flow architecture is presented. The basic concepts of disease modeling that oriented the design of the core information model are explained. Disease phases, milestones, cases stratification group in each phase, key relevant factors, and outcomes are defined. Data processing and disease model visualization tools are presented. Most relevant contributions to the literature resulting from the exploitation of the infrastructure are reviewed, and future perspectives are discussed.
- Published
- 2019
34. Multisociety consensus quality improvement guidelines for intraarterial catheter-directed treatment of acute ischemic stroke, from the American Society of Neuroradiology, Canadian Interventional Radiology Association, Cardiovascular and Interventional Rad
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Christophe Cognard, Daniel A. Rüfenacht, Stephen R. Ramee, Tudor G. Jovin, Donald Frei, Bryan Kluck, J.J. Connors, Rishi Gupta, Dierk Vorwerk, Philip M. Meyers, Kieran J. Murphy, Carl M. Black, M.J. Bernadette Stallmeyer, and David Sacks
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medicine.medical_specialty ,Consensus ,Time Factors ,Quality management ,medicine.medical_treatment ,MEDLINE ,Revascularization ,Brain Ischemia ,Fibrinolytic Agents ,Predictive Value of Tests ,Modified Rankin Scale ,medicine ,Humans ,Infusions, Intra-Arterial ,Thrombolytic Therapy ,Radiology, Nuclear Medicine and imaging ,Intensive care medicine ,Stroke ,Quality Indicators, Health Care ,Neuroradiology ,medicine.diagnostic_test ,business.industry ,Endovascular Procedures ,Interventional radiology ,General Medicine ,Guideline ,medicine.disease ,Quality Improvement ,Surgery ,Benchmarking ,Treatment Outcome ,Door-to-balloon ,Cardiology and Cardiovascular Medicine ,business ,Fibrinolytic agent - Abstract
Purpose In this international multispecialty document, quality benchmarks for processes of care and clinical outcomes are defined. It is intended that these benchmarks be used in a quality assurance program to assess and improve processes and outcomes in acute stroke revascularization. Materials and Methods Members of the writing group were appointed by the American Society of Neuroradiology, Canadian Interventional Radiology Association, Cardiovascular and Interventional Radiological Society of Europe, Society of Cardiac Angiography and Interventions, Society of Interventional Radiology, Society of NeuroInterventional Surgery, European Society of Minimally Invasive Neurological Therapy, and Society of Vascular and Interventional Neurology. The writing group reviewed the relevant literature from 1986 through February 2012 to create an evidence table summarizing processes and outcomes of care. Performance metrics and thresholds were then created by consensus. The guideline was approved by the sponsoring societies. It is intended that this guideline be fully updated in 3 years. Results In this international multispecialty document, quality benchmarks for processes of care and clinical outcomes are defined. These include process measures of time to imaging, arterial puncture, and revascularization and measures of clinical outcome up to 90 days. Conclusions Quality improvement guidelines are provided for endovascular acute ischemic stroke revascularization procedures. © 2013 Wiley Periodicals, Inc.
- Published
- 2013
35. Endovaskuläre Aneurysmatherapie
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Michael Forsting, Daniel A. Rüfenacht, and Isabel Wanke
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Medizin ,Neurology (clinical) ,Family Practice - Abstract
ZusammenfassungDas Blutungsrisiko intrakranieller Aneurysmen ist multifaktoriell und hängt neben anderen Faktoren nicht nur von der Aneurysmalokalisation und -größe ab, sondern auch von der Aneurysmakonfiguration. Ein unregelmäßig geformtes Aneurysma ist gekennzeichnet durch umschriebene Schwachstellen, entstanden als mögliche Reaktion thrombusinduzierter reaktiver Entzündung. Dies wird als Vorläufer der Aneurysmaruptur angesehen. Aktuelle Metaanalysen zeigen, dass die endovaskuläre Therapie (EVT) nicht rupturierter Aneurysmen im Vergleich zur neurochirurgischen Ausschaltung mit niedrigerer Morbidität und Letalität durchgeführt werden kann. Zu berücksichtigen ist, dass Rezidivbehandlungen nach EVT insbesondere bei Aneurysmen größer als 15 mm vorkommen. Die Indikation zur Behandlung eines nicht rupturierten Aneurysmas sollten in der Aneurysmatherapie erfahrene Ärzte interdisziplinär vornehmen. Die Verfahren und die sich stetig neu entwickelnden medizinischen Produkte zur endovaskulären Aneurysmatherapie ermöglichen, dass eine Vielzahl von Aneurysmen endovaskulär mit hoher Effizienz versorgt werden können. Der Einsatz eines Flow diverter ist sehr effektiv zur Aneurysmabehandlung, die Indikation muss aufgrund von Ischämierisiken, insbesondere an Gefäßen mit Perforatoren, jedoch sehr streng gestellt werden.
- Published
- 2013
36. Safety and effectiveness of large volume coils in the treatment of small aneurysms
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H Hawk, Sophia Göricke, Daniel A. Rüfenacht, Kiriaki Kolia, Isabel Wanke, Stephan G. Wetzel, Steven Quarfordt, Justin Calvert, Zsolt Kulcsar, and Blaise Baxter
- Subjects
medicine.medical_specialty ,business.industry ,Penumbra ,Medizin ,Prospective data ,General Medicine ,medicine.disease ,030218 nuclear medicine & medical imaging ,Aneurysm rupture ,03 medical and health sciences ,0302 clinical medicine ,Aneurysm ,Thromboembolic complication ,Occlusion ,medicine ,Retrospective analysis ,Surgery ,Neurology (clinical) ,Radiology ,business ,030217 neurology & neurosurgery ,Volume (compression) - Abstract
Background and purposeLarge volume soft design coils facilitate quicker aneurysm filling and high packing density. Our purpose was to analyze the feasibility, safety, and effectiveness of the Penumbra Coil 400 (PC400) system in the treatment of small aneurysms.Materials and methodsA retrospective analysis of prospective data collected at three different centers was performed on consecutive aneurysms ResultsMean aneurysm size was 5.8±2.0 mm. An average of 2.5±1.3 coils with a mean length of 18±16 cm per aneurysm was used, resulting in a mean packing density of 45.6±14.4%. The thromboembolic event rate was 3.3% and no procedural aneurysm rupture was observed. Immediate adequate occlusion was achieved in 66% of aneurysms. During a mean follow-up period of 7.4 months the number of adequate occlusions increased to 91%.ConclusionsLarge volume PC 400 coils are safe and effective in the treatment of small aneurysms with a low thromboembolic complication rate and no hemorrhagic events. High packing densities are achieved with a low average number of coils used per aneurysm treated. The aneurysms demonstrated progressive occlusion over time, which probably suggests stability in the long term.
- Published
- 2016
37. Intra-Aneurysmal Pressure and Flow Changes Induced by Flow Diverters: Relation to Aneurysm Size and Shape
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Alejandro F. Frangi, Zsolt Kulcsar, Hernán G. Morales, Daniel A. Rüfenacht, Ignacio Larrabide, A. J. Geers, and M. L. Aguilar
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medicine.medical_specialty ,Databases, Factual ,Hemodynamics ,Blood Pressure ,Fusiform Aneurysm ,Aneurysm ,Internal medicine ,medicine ,Humans ,Computer Simulation ,Radiology, Nuclear Medicine and imaging ,cardiovascular diseases ,Thrombus ,Interventional ,business.industry ,Endovascular Procedures ,Models, Cardiovascular ,Intracranial Aneurysm ,Thrombosis ,Blood flow ,medicine.disease ,Surgery ,medicine.anatomical_structure ,Blood pressure ,Cerebrovascular Circulation ,cardiovascular system ,Vascular resistance ,Cardiology ,Vascular Resistance ,Neurology (clinical) ,business ,Blood Flow Velocity - Abstract
BACKGROUND AND PURPOSE: Effects of blood flow modification by flow diverters are observed to lead often to aneurysm thrombosis and reverse remodeling. For this process, to further understand the potential roles of intra-aneurysmal blood pressure changes and aneurysm morphologies, 23 patients were studied by numeric simulation. MATERIALS AND METHODS: 3D imaging of aneurysms of different sizes and shapes, all located at the supraclinoid segment of the ICA (n 23), was prepared for CFD simulations. Hemodynamic variables were calculated for conditions before and after virtual FD implantation, reconstituting a vessel wall scaffold across the aneurysm neck. WSS, velocity, residence time, turnover time, and intra-aneurysmal pressure were assessed statistically. RESULTS: After placement of FDs, significant reductions inside the aneurysm were observed for most hemodynamic variables (P .01) except mean intra-aneurysmal pressures. For minimum/maximum intra-aneurysmal pressure values, small but significant changes were found; however, they were considered too small to be of relevance. CONCLUSIONS: Calculations in 23 cases did not reveal significant intra-aneurysmal mean or peak pressure changes, indicating a minor role of pressure changes in the rare event of secondary ruptures after FD use. Other hemodynamic variables (WSS and velocity) exhibited more significant changes, indicating their role in intra-aneurysmal thrombus formation. Size-dependent, significantly higher reduction in WSS (P .069) and velocity (P .013) was observed in small aneurysms compared with larger ones. When it came to shape, there were significantly higher reductions in WSS (P .055) and velocity (P .065) and a significantly higher increase in turnover time in fusiform aneurysms compared with saccular aneurysms. ABBREVIATIONS: CFD computational fluid dynamics; FD flow diverter; IA intracranial aneurysm; WSS wall shear stress
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- 2012
38. Influence of segmentation on morphological parameters and computed hemodynamics in cerebral aneurysms
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Rafik Ouared, Daniel A. Rüfenacht, Nikos Stergiopulos, Luca Augsburger, Vitor Mendes Pereira, Philippe Reymond, and Olivier Brina
- Subjects
medicine.medical_specialty ,Aspect ratio ,business.industry ,Mechanical Engineering ,Blood flow ,Vorticity ,Computational fluid dynamics ,medicine.disease ,Surgery ,Shear (sheet metal) ,Aneurysm ,Mechanics of Materials ,medicine ,Shear stress ,General Materials Science ,Segmentation ,business ,Biomedical engineering ,Mathematics - Abstract
This article focuses on the effects of segmentation on cerebral aneurysm's morphological parameters and on blood flow patterns computed using computational fluid dynamics. Segmentation is a non-negligible source of uncertainty that may have a consequent impact on the morphological assessment and the resulting hemodynamical simulations, the latter potentially being a key element in the decision-making therapeutic armamentarium for neuroradiologists and neurosurgeons. From the three patient-specific cases investigated, medical imaging data sets were collected, and four different three-dimensional segmentations were generated by the same senior technician. Morphological parameters were measured, and the aspect ratio was derived. Numerical simulations were performed; flow pattern changes, their impact on wall shear stress (WSS) and their sensitivity within the four reconstructed geometries were analyzed. Aneurysm velocity, vorticity and shear magnitudes were computed and compared. The morphological parameters having the highest variability were the aneurysm lobe dimensions (20 %). The neck length was the second parameter presenting the highest variability (21 %). The neck width variability reached 13.8 %, and the aspect ratio variability reached 14.2 %. The artery height and the artery width presented a variability of 13.7 and 10.8 %, respectively. Finally, the aneurysm depth, aneurysm height and aneurysm width presented variabilities of 12.8, 9.4 and 7.3 %, respectively. Differences in the flow path lines, velocity magnitude, wall shear stress and vorticity are also reported and discussed. The average variability reached 15.6 % for velocity, 25.2 % for vorticity and 25.2 % for shear, these parameters being computed inside the aneurysm. The maximum variability reached 31.0 % for velocity, 54.8 % for vorticity and 58.1 % for shear. A segmentation process reconstructing anatomies that is less sensitive to human intervention would be a future goal worth pursuing.
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- 2012
39. Fast virtual deployment of self-expandable stents: method and in vitro evaluation for intracranial aneurysmal stenting
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Minsuok Kim, Daniel A. Rüfenacht, Luca Augsburger, Alejandro F. Frangi, Maria-Cruz Villa-Uriol, and Ignacio Larrabide
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Deformable Models ,Percutaneous ,Computer science ,medicine.medical_treatment ,02 engineering and technology ,Pattern Recognition, Automated ,0302 clinical medicine ,Radiological and Ultrasound Technology ,Artery ,Computer Graphics and Computer-Aided Design ,Dynamics ,Surgery, Computer-Assisted ,In vitro validation ,Contrast injection ,cardiovascular system ,Radiographic Image Interpretation, Computer-Assisted ,Stents ,Computer Vision and Pattern Recognition ,Radiology ,Tomography ,Intracranial aneurysms ,Cfd ,Simulation ,medicine.medical_specialty ,0206 medical engineering ,Health Informatics ,Finite-Element-Analysis ,Sensitivity and Specificity ,Imaging phantom ,Expanding Stent ,Prosthesis Implantation ,03 medical and health sciences ,Blood vessel prosthesis ,medicine ,Humans ,Simplex deformable models ,Radiology, Nuclear Medicine and imaging ,cardiovascular diseases ,Coronary Stents ,Placement ,Self expandable ,Virtual stenting ,Hemodynamics ,Stent ,Reproducibility of Results ,Intracranial Aneurysm ,Virtual angiography ,equipment and supplies ,020601 biomedical engineering ,Blood Vessel Prosthesis ,Cerebral Angiography ,Tomography, X-Ray Computed ,Stent design ,030217 neurology & neurosurgery ,Object Reconstruction ,Biomedical engineering - Abstract
Introduction: Minimally invasive treatment approaches, like the implantation of percutaneous stents, are becoming more popular every day for the treatment of intracranial aneurysms. The outcome of such treatments is related to factors like vessel and aneurysm geometry, hemodynamic conditions and device design. For this reason, having a tool for assessing stenting alternatives beforehand is crucial. Methodology: The Fast Virtual Stenting (FVS) method, which provides an estimation of the configuration of intracranial stents when released in realistic geometries, is proposed in this paper. This method is based on constrained simplex deformable models. The constraints are used to account for the stent design. An algorithm for its computational implementation is also proposed. The performance of the proposed methodology was contrasted with real stents released in a silicone phantom. Results: In vitro experiments were performed on the phantom where a contrast injection was performed. Subsequently, corresponding Computational Fluid Dynamics (CFD) analyzes were carried out on a digital replica of the phantom with the virtually released stent. Virtual angiographies are used to compare in vitro experiments and CFD analysis. Contrast time–density curves for in vitro and CFD data were generated and used to compare them. Conclusions: Results of both experiments resemble very well, especially when comparing the contrast density curves. The use of FVS methodology in the clinical environment could provide additional information to clinicians before the treatment to choose the therapy that best fits the patient.
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- 2012
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40. Combination of Rare Right Arterial Variation with Anomalous Origins of the Vertebral Artery, Aberrant Subclavian Artery and Persistent Trigeminal Artery
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Hasan Yilmaz, H. Ishihara, Karl-Olof Lövblad, German Abdo, Daniel A. Rüfenacht, Fumio Asakura, and D. San Millán Ruíz
- Subjects
Adult ,medicine.medical_specialty ,Subarachnoid hemorrhage ,Carotid Artery, Common ,Vertebral artery ,Subclavian Artery ,Aorta, Thoracic ,Aberrant subclavian artery ,Right Common Carotid Artery ,medicine.artery ,Internal medicine ,medicine ,Humans ,Right vertebral artery ,cardiovascular diseases ,Vertebral Artery ,medicine.diagnostic_test ,business.industry ,Original Articles ,Subarachnoid Hemorrhage ,medicine.disease ,Cerebral Angiography ,medicine.anatomical_structure ,Basilar Artery ,Descending aorta ,Angiography ,cardiovascular system ,Cardiology ,Trigeminal artery ,Female ,business - Abstract
A 32-year-old woman hospitalized for subarachnoid hemorrhage showed rare arterial variation on the right side with anomalous origins of the vertebral artery, aberrant subclavian artery and persistent trigeminal artery. Angiography showed the right vertebral artery to originate from the right common carotid artery, the right subclavian artery to arise separately from the descending aorta, and persistent trigeminal artery on the right side. The possible embryonic mechanism of this previously unreported variant combination is discussed.
- Published
- 2011
41. Intracranial stents being modeled as a porous medium: flow simulation in stented cerebral aneurysms
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Daniel A. Rüfenacht, Nikolaos Stergiopulos, Philippe Reymond, and Lucas Augsburger
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Materials science ,0206 medical engineering ,Biomedical Engineering ,02 engineering and technology ,Computational fluid dynamics ,Flow simulation ,Endovascular Treatment ,Intracranial Aneurysm/physiopathology/surgery ,Complex Hemodynamics ,03 medical and health sciences ,0302 clinical medicine ,Aneurysm ,Blood-Flow ,medicine ,Shear stress ,Humans ,Device ,Computer Simulation ,cardiovascular diseases ,Intracranial stent ,Cerebral aneurysm ,Placement ,business.industry ,Models, Cardiovascular ,Porous medium ,Intracranial Aneurysm ,Mechanics ,Equipment Design ,Vorticity ,medicine.disease ,020601 biomedical engineering ,ddc:616.8 ,Blood Vessel Prosthesis ,Shear (sheet metal) ,Shear rate ,Equipment Failure Analysis ,Flow (mathematics) ,Cerebrovascular Circulation ,cardiovascular system ,Computer-Aided Design ,Stents ,business ,Porosity ,Coil Embolization ,030217 neurology & neurosurgery ,Biomedical engineering - Abstract
Intracranial aneurysms may be treated by flow diverters, alternatively to stents and coils combination. Numerical simulation allows the assessment of the complex nature of aneurismal flow. Endovascular devices present a rather dense and fine strut network, increasing the complexity of the meshing. We propose an alternative strategy, which is based on the modeling of the device as a porous medium. Two patient-specific aneurysm data sets were reconstructed using conventional clinical setups. The aneurysms selection was done so that intra-aneurismal flow was shear driven in one and inertia driven in the other. Stents and their porous medium analog were positioned at the aneurysm neck. Physiological flow and standard boundary conditions were applied. The comparison between both approaches was done by analyzing the velocity, vorticity, and shear rate magnitudes inside the aneurysm as well as the wall shear stress (WSS) at the aneurysm surface. Simulations without device were also computed. The average flow reduction reaches 76 and 41% for the shear and inertia driven flow models, respectively. When comparing the two approaches, results show a remarkable similarity in the flow patterns and magnitude. WSS, iso-velocity surfaces and velocity on a trans-sectional plane are in fairly good agreement. The root mean squared error on the investigated parameters reaches 20% for aneurysm velocity, 30.6% for aneurysm shear rate, and 47.4% for aneurysm vorticity. It reaches 20.6% for WSS computed on the aneurysm surface. The advantages of this approach reside in its facility to implement and in the gain in computational time. Results predicted by the porous medium approach compare well with the real stent geometry model and allow predicting the main effects of the device on intra-aneurismal flow, facilitating thus the analysis.
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- 2011
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42. Use of the Enterprise™ Intracranial Stent for Revascularization of Large Vessel Occlusions in Acute Stroke
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Daniel A. Rüfenacht, Roman Sztajzel, Hasan Yilmaz, Zsolt Kulcsar, Benjamin Gory, Christophe Bonvin, and Karl-Olof Lövblad
- Subjects
Adult ,Male ,medicine.medical_specialty ,medicine.medical_treatment ,Intracranial stent ,Prosthesis Design ,Revascularization ,ddc:616.0757 ,Blood vessel prosthesis ,Internal medicine ,medicine ,Humans ,Radiology, Nuclear Medicine and imaging ,cardiovascular diseases ,Aged ,Acute stroke ,Neuroradiology ,Cerebral Revascularization ,business.industry ,Stent ,Thrombolysis ,Middle Aged ,Blood Vessel Prosthesis ,ddc:616.8 ,Equipment Failure Analysis ,Radiography ,Stroke ,Treatment Outcome ,Cardiology ,Female ,Stents ,Cerebral Arterial Diseases ,Neurology (clinical) ,Neurosurgery ,Radiology ,business - Abstract
Background and Purpose:: Major cerebral thromboembolism often resists recanalization with currently available techniques. The authors present their initial experience with a self-expanding stent for use in intracranial vascular reconstruction, permitting immediate recanalization of acute thromboembolic occlusions of the anterior circulation. Patients and Methods:: Patients treated with the Cordis Enterprise™ self-expanding intracranial stent system for acute thromboembolic occlusion of the major anterior cerebral arteries were included. Treatment comprised systemic and intraarterial thrombolysis, mechanical thrombectomy, and stent placement. Stent deployment, recanalization rate by means of Thrombolysis In Cerebral Infarction (TICI) scores and the clinical outcome were all assessed. Results:: Six patients presenting with acute carotid T (n = 2) or proximal middle cerebral artery occlusion (n = 4) were treated. The mean National Institutes of Health Stroke Scale (NIHSS) score at presentation was 14; the mean age was 57 years. Successful stent deployment and immediate recanalization were achieved in all six with a TICI score of ≥ 2. Neither distal emboli nor any procedure-related complications were encountered. One patient developed symptomatic intracerebral hemorrhage and two patients needed decompressive craniectomy after treatment. The mean NIHSS score at 10 days was 10, but only one patient showed a complete recovery at 3 months. Conclusion:: Intracranial placement of the Enterprise™ self-expanding stent has proven to be feasible and efficient in achieving immediate recanalization of occluded main cerebral arteries. The use of antiplatelet therapy after treatment may, however, increase the risk of reperfusion intracerebral hemorrhage
- Published
- 2010
43. Automated cement segmentation in vertebroplasty
- Author
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Nina Kozic, Stephen J. Ferguson, Daniel A. Rüfenacht, Mauricio Reyes, Miguel Ángel González Ballester, German Abdo, and Stefan Weber
- Subjects
Leak ,medicine.medical_specialty ,Computer science ,02 engineering and technology ,03 medical and health sciences ,0302 clinical medicine ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,Humans ,Segmentation ,Spinal canal ,Cement ,Vertebroplasty ,Lumbar Vertebrae ,Bone Cements ,Soft tissue ,Models, Theoretical ,Bone cement ,Computer Science Applications ,Vertebral body ,Treatment Outcome ,medicine.anatomical_structure ,Osteoporosis ,Spinal Diseases ,020201 artificial intelligence & image processing ,Surgery ,Radiology ,Tomography, X-Ray Computed ,Family Practice ,030217 neurology & neurosurgery ,Extravasation of Diagnostic and Therapeutic Materials ,Cement leakage - Abstract
Vertebroplasty is a minimally invasive procedure with many benefits; however, the procedure is not without risks and potential complications, of which leakage of the cement out of the vertebral body and into the surrounding tissues is one of the most serious. Cement can leak into the spinal canal, venous system, soft tissues, lungs and intradiscal space, causing serious neurological complications, tissue necrosis or pulmonary embolism. We present a method for automatic segmentation and tracking of bone cement during vertebroplasty procedures, as a first step towards developing a warning system to avoid cement leakage outside the vertebral body. We show that by using active contours based on level sets the shape of the injected cement can be accurately detected. The model has been improved for segmentation as proposed in our previous work by including a term that restricts the level set function to the vertebral body. The method has been applied to a set of real intra-operative X-ray images and the results show that the algorithm can successfully detect different shapes with blurred and not well-defined boundaries, where the classical active contours segmentation is not applicable. The method has been positively evaluated by physicians.
- Published
- 2010
44. Methodologies to assess blood flow in cerebral aneurysms: Current state of research and perspectives
- Author
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Edouard Fonck, Daniel A. Rüfenacht, Mohamed Farhat, Nikolaos Stergiopulos, Luca Augsburger, Makoto Ohta, Zsolt Kulcsar, and Philippe Reymond
- Subjects
medicine.medical_specialty ,Pulsatile flow ,Models, Neurological ,Diagnostic Techniques, Cardiovascular ,Computational fluid dynamics ,Aneurysm ,medicine ,Humans ,blood flow ,Cerebral aneurysms ,Radiology, Nuclear Medicine and imaging ,Arterial wall ,Blood flow assessment ,Endovascular treatment ,Radiological and Ultrasound Technology ,Models, Cardiovascular ,Intracranial Aneurysm ,Blood flow ,Flow pattern ,medicine.disease ,Particle image velocimetry ,Surgery ,cerebral aneurysm ,Particle Image Velocimetry ,Risk analysis (engineering) ,Flow (mathematics) ,Cerebrovascular Circulation ,Neurology (clinical) ,Current (fluid) - Abstract
With intracranial aneurysms disease bringing a weakened arterial wall segment to initiate, grow and potentially rupture an aneurysm, current understanding of vessel wall biology perceives the disease to follow the path of a dynamic evolution and increasingly recognizes blood flow as being one of the main stakeholders driving the process. Although currently mostly morphological information is used to decide on whether or not to treat a yet unruptured aneurysm, among other factors, knowledge of blood flow parameters may provide an advanced understanding of the mechanisms leading to further aneurismal growth and potential rupture. Flow patterns, velocities, pressure and their derived quantifications, such as shear and vorticity, are today accessible by direct measurements or can be calculated through computation. This paper reviews and puts into perspective current experimental methodologies and numerical approaches available for such purposes. In our view, the combination of current medical imaging standards, numerical simulation methods and endovascular treatment methods allow for thinking that flow conditions govern more than any other factor fate and treatment in cerebral aneurysms. Approaching aneurysms from this perspective improves understanding, and while requiring a personalized aneurysm management by flow assessment and flow correction, if indicated.
- Published
- 2009
45. Effect of Aging on Elastin Functionality in Human Cerebral Arteries
- Author
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Michael Unser, Daniel A. Rüfenacht, Daniel Sage, Jean H.D. Fasel, Georg Feigl, Nikolaos Stergiopulos, and Edouard Fonck
- Subjects
Adult ,Male ,Senescence ,Aging ,Pathology ,medicine.medical_specialty ,Cerebral arteries ,medicine ,Humans ,Arterial wall ,Aged ,Aged, 80 and over ,Advanced and Specialized Nursing ,Human aorta ,biology ,Vascular disease ,business.industry ,Cerebral Arteries ,Middle Aged ,medicine.disease ,Elastin degradation ,Biomechanical Phenomena ,Elastin ,cardiovascular system ,biology.protein ,Female ,Collagen ,Neurology (clinical) ,Tunica Intima ,Cardiology and Cardiovascular Medicine ,business - Abstract
Background and Purpose— Aging affects elastin, a key component of the arterial wall integrity and functionality. Elastin degradation in cerebral vessels is associated with cerebrovascular disease. The goal of this study is to assess the biomechanical properties of human cerebral arteries, their composition, and their geometry, with particular focus on the functional alteration of elastin attributable to aging. Methods— Twelve posterior cranial arteries obtained from human cadavers of 2 different age groups were compared morphologically and tested biomechanically before and after enzymatic degradation of elastin. Light, confocal, and scanning electron microscopy were used to analyze and determine structural differences, potentially attributed to aging. Results— Aging affects structural morphology and the mechanical properties of intracranial arteries. In contrast to main systemic arteries, intima and media thicken while outer diameter remains relatively constant with age, leading to concentric hypertrophy. The structural morphology of elastin changed from a fiber network oriented primarily in the circumferential direction to a more heterogeneously oriented fiber mesh, especially at the intima. Biomechanically, cerebral arteries stiffen with age and lose compliance in the elastin dominated regime. Enzymatic degradation of elastin led to loss in compliance and stiffening in the young group but did not affect the structural and material properties in the older group, suggesting that elastin, though present in equal quantities in the old group, becomes dysfunctional with aging. Conclusions— Elastin loses its functionality in cerebral arteries with aging, leading to stiffer less compliant arteries. The area fraction of elastin remained, however, fairly constant. The loss of functionality may thus be attributed to fragmentation and structural reorganization of elastin occurring with age.
- Published
- 2009
46. Subtracted vortex centers path line method with cinematic angiography for measurement of flow speed in cerebral aneurysms
- Author
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Makoto Ohta, Daniel A. Rüfenacht, Karl-Olof Lövblad, Naoko Fujimura, German Abdo, Hasan Yilmaz, Krisztina Barath, Luca Augsburger, University of Zurich, and Ohta, M
- Subjects
Middle Cerebral Artery ,medicine.medical_specialty ,Materials science ,Image Processing, Computer-Assisted/methods ,Pulsatile flow ,610 Medicine & health ,Image processing ,ddc:616.0757 ,Aneurysm ,10043 Clinic for Neuroradiology ,Image Processing, Computer-Assisted ,medicine ,Humans ,Slipstream ,cardiovascular diseases ,Regional Blood Flow/physiology ,medicine.diagnostic_test ,Phantoms, Imaging ,Blood Flow Velocity/physiology ,Hemodynamics ,Models, Cardiovascular ,Intracranial Aneurysm ,General Medicine ,Blood flow ,medicine.disease ,Cerebral Angiography ,ddc:616.8 ,Vortex ,2728 Neurology (clinical) ,Middle Cerebral Artery/physiopathology ,Neurology ,Flow velocity ,Regional Blood Flow ,2808 Neurology ,Angiography ,Cerebral Angiography/methods ,Intracranial Aneurysm/physiopathology ,Neurology (clinical) ,Radiology ,Blood Flow Velocity ,Biomedical engineering - Abstract
BACKGROUND AND PURPOSE: The assessment of blood flow speed by imaging modalities is of increasing importance for endovascular treatment, such as stent implantation, of cerebral aneurysms. The subtracted vortex centers path line method (SVC method) utilizes image post-processing for determining flow quantitatively. In current practice, intra-aneurysmal flow in an in vitro model is visualized by laser sheet translumination and digitally recorded. In this study, we applied this method to cinematic angiography (CA), which is the preferred imaging method for endovascular interventions, to analyse hemodynamic changes. The SVC method was applied to the images and compared with results of the slipstream line method with colored fluid. METHODS: A transparent tubular model was constructed of silicone which included an aneurysm 10 mm in diameter and having a 5 mm neck on a straight parent artery with a diameter of 3.5 mm. The model was integrated into a pulsatile circulation system. By CA, successive images at 25 frames/s with injection of contrast were obtained. RESULTS AND CONCLUSION: Rotating vortexes of contrast, which advanced along the wall of the aneurysm, were observed in successive images of the aneurysm cavity. This phenomenon was also observed in the successive images with the slipstream line method. The speed of the vortex center was calculated and the results show that the vortex speed of CA was the same as that under the slipstream line method. This indicates the possibility of applying the SVC method to medical imaging equipment for analysis of the flow in aneurysms containing stent.
- Published
- 2008
47. Three-Dimensional Reconstruction of a Cerebral Stent using Micro-CT for Computational Simulation
- Author
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Daniel A. Rüfenacht, Makoto Ohta, Akira Takahashi, Toshio Nakayama, and Chuan He
- Subjects
Computer science ,business.industry ,Mechanical Engineering ,medicine.medical_treatment ,Stent ,Fluid mechanics ,Blood flow ,Computational fluid dynamics ,medicine.disease ,Aneurysm ,Electromagnetic coil ,medicine ,General Materials Science ,cardiovascular diseases ,Implant ,business ,Image resolution ,Biomedical engineering - Abstract
The surface geometry of an intracranial stent (ICS) for a cerebral aneurysm is reconstructed by using micro-CT to import computational fluid simulations. The reconstructed stent with STL format is composed of 170,948 triangles with 0.04mm spatial resolutions. The boundary condition of the surface is clear without any reflection effects by X-ray introduced into the stainless steel stent. The computational simulations of blood flow with small implants, such as a stent or coil will be a designable way to control blood flow in/on a cerebral aneurysm and repair the disease. Micro-CT has a possibility of detecting the 3-D geometry of a small implant, such as ICS and may be useful to 3-D reconstruction and integration to computational simulation.
- Published
- 2007
48. [Not Available]
- Author
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Isabel, Wanke and Daniel A, Rüfenacht
- Subjects
Europe ,Neurology ,Neurosurgery ,Minimally Invasive Surgical Procedures ,Organizational Objectives ,Radiography, Interventional ,Radiology ,Societies, Medical - Published
- 2015
49. Changes in volume of giant intracranial aneurysms treated by surgical strategies other than direct clipping
- Author
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Nicolai Maldaner, Susanne Guhl, Dorothee Mielke, Peter Vajkoczy, Christian Musahl, Julius Dengler, Maria Wostrack, Nils Ole Schmidt, and Daniel A. Rüfenacht
- Subjects
Adult ,Male ,medicine.medical_specialty ,medicine.medical_treatment ,Medizin ,Neurosurgical Procedures ,Interquartile range ,Occlusion ,medicine ,Humans ,Neuroradiology ,Aged ,Retrospective Studies ,medicine.diagnostic_test ,business.industry ,Retrospective cohort study ,Interventional radiology ,Intracranial Aneurysm ,Clipping (medicine) ,Middle Aged ,Surgical Instruments ,Surgery ,medicine.anatomical_structure ,Ventricle ,Female ,Neurology (clinical) ,Neurosurgery ,business - Abstract
Giant intracranial aneurysms (GIA) are often not eligible for direct clip occlusion. Surgical alternatives include partial clip occlusion or the placement of a cerebrovascular bypass or the combination of both. These alternative indirect strategies are expected to lead to a decrease in GIA volume over time rather than instantaneously. To examine whether this is the case, we analyzed follow-up imaging results 1 year after surgery. We retrospectively screened the prospective GIA Registry’s imaging database for anterior circulation GIA treated by surgical strategies other than direct clipping. We measured pre- and 1-year post-treatment GIA volume, lateral ventricle volume (LVV), and mid-line shift (MLS) in 19 cases. After a mean follow-up of 466 days (standard deviation ±171) GIA volumes decreased from 9.6 cm3 (interquartile range (IQR) 6.1–14.1) to 4.3 cm3 (IQR 2.9–5.7; p
- Published
- 2015
50. European Society of Minimally Invasive Neurological Therapy (ESMINT)
- Author
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Daniel A. Rüfenacht and Isabel Wanke
- Subjects
medicine.medical_specialty ,Neurology ,business.industry ,General surgery ,Neurological therapy ,medicine ,Medizin ,Radiology, Nuclear Medicine and imaging ,Neurology (clinical) ,Neurosurgery ,business ,Neuroradiology - Published
- 2015
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