Okka W Hamer

University Hospital Regensburg, Ratisbon, Bavaria, Germany

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Publications (126)312.79 Total impact

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    ABSTRACT: In this review article, state-of-the-art diagnostic tools and innovative treatments of thymoma and thymic carcinoma (TC) are described with special respect to advanced tumour stages. Complete surgical resection (R0) remains the standard therapeutic approach for almost all a priori resectable mediastinal tumours as defined by preoperative standard computed tomography (CT). If lymphoma or germ-cell tumours are differential diagnostic considerations, biopsy may be indicated. Resection status is the most important prognostic factor in thymoma and TC, followed by tumour stage. Advanced (Masaoka-Koga stage III and IVa) tumours require interdisciplinary therapy decisions based on distinctive findings of preoperative CT scan and ancillary investigations [magnetic resonance imaging (MRI)] to select cases for primary surgery or neoadjuvant strategies with optional secondary resection. In neoadjuvant settings, octreotide scans and histological evaluation of pretherapeutic needle biopsies may help to choose between somatostatin agonist/prednisolone regimens and neoadjuvant chemotherapy as first-line treatment. Finally, a multimodality treatment regime is recommended for advanced and unresectable thymic tumours. In conclusion, advanced stage thymoma and TC should preferably be treated in experienced centres in order to provide all modern diagnostic tools (imaging, histology) and innovative therapy techniques. Systemic and local (hyperthermic intrathoracic chemotherapy) medical treatments together with extended surgical resections have increased the therapeutic options in patients with advanced or recurrent thymoma and TC.
    No preview · Article · Dec 2015 · European journal of cardio-thoracic surgery: official journal of the European Association for Cardio-thoracic Surgery

  • No preview · Article · Sep 2015 · European Respiratory Journal
  • D Wormanns · O W Hamer
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    ABSTRACT: The Fleischner Society has published several recommendations for terms for thoracic imaging. The most recent glossary was released in 2008. One glossary in German language was published in 1996. This review provides an updated German glossary of terms for thoracic imaging. It closely adheres to the Fleischner Society terminology. In some instances adaptions to the usage of German language were necessary, as well as some additions of terms which were later defined or redefined. These deviations are summarized in a revision report. Key Points: • The Fleischner Society has published a revised version of her glossary of terms for thoracic imaging in 2008. This paper presents a German adaption of this glossary.• Some terms not contained in the original version have been added.• The general use of the presented terminology in radiological reports is recommended. © Georg Thieme Verlag KG Stuttgart · New York.
    No preview · Article · Aug 2015 · RöFo - Fortschritte auf dem Gebiet der R
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    ABSTRACT: Macrophages are crucially involved in the pathophysiology of acute pancreatitis. Soluble CD163 (sCD163) is specifically released from macrophages and systemic levels are increased in inflammatory diseases. Here, sCD163 was measured in serum of 50 patients with acute pancreatitis to find out possible associations with disease activity. Admission levels of systemic sCD163 were nearly three-fold higher in patients with acute pancreatitis compared to controls. In patients sCD163 did not correlate with C-reactive protein and leukocyte count as established markers of inflammation. Levels were not associated with disease severity assessed by the Schroeder score, Balthazar score, Acute Physiology, Age, and Chronic Health Evaluation (Apache) II score and peripancreatic necrosis score. Soluble CD163 was not related to complications of acute pancreatitis. These data show that serum sCD163 is increased in acute pancreatitis indicating activation of macrophages but is not associated with disease severity and outcome. Copyright © 2015. Published by Elsevier Inc.
    No preview · Article · Jul 2015 · Experimental and Molecular Pathology
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    ABSTRACT: Medikamenteninduzierte interstitielle Lungenerkrankungen (engl. „drug-induced interstitial lung diseases“, DILD) sind wahrscheinlich häufiger, als sie diagnostiziert werden. Aufgrund ihrer potenziellen Reversibilität ist eine erhöhte Vigilanz gegenüber DILD auch seitens der Radiologie angebracht, da diese regelmäßig ein radiomorphologisches Korrelat in der hochauflösenden Computertomographie („high-resolution CT“, HRCT) der Lunge aufweisen. Typische, nach eigener Erfahrung relativ häufige Manifestationsformen von DILD sind der diffuse Alveolarschaden (engl. „diffuse alveolar damage“, DAD), die eosinophile Pneumonie (EP), die Hypersensitivitätspneumonitis (HP), die organisierende Pneumonie (OP), die nichtspezifische interstitielle Pneumonie (NSIP) und die gewöhnliche interstitielle Pneumonie („usual interstitial pneumonia“, UIP). Diese Muster werden anhand von Fallbeispielen vorgestellt, wobei auf die Einbettung in den klinischen Kontext Wert gelegt wird. Dies soll die Bedeutung des interdisziplinären Austauschs bei der Diagnose von DILD unterstreichen, da es sich fast immer um eine Ausschluss- bzw. Wahrscheinlichkeitsdiagnose handelt. Differenzialdiagnostisch hilfreiche Hinweise auf das Vorliegen einer DILD, wie z. B. eine Eosinophilie oder die erhöhte CT-Dichte pulmonaler Konsolidierungen bei der Amiodaron-induzierten Pneumopathie, werden erwähnt und die frei verfügbare Online-Datenbank http://www.pneumotox.com vorgestellt.
    No preview · Article · Dec 2014 · Der Radiologe
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    ABSTRACT: Structural and functional integrity of the right heart is important in the prognosis after acute myocardial infarction (AMI). The objective of this study was to assess the impact of sleep disordered breathing (SDB) on structure and function of the right heart early after AMI. 54 patients underwent cardiovascular magnetic resonance 3-5 days and 12 weeks after AMI, and were stratified according to the presence of SDB, defined as an apnoea-hypopnoea index of ≥15 events·h(-1). 12 weeks after AMI, end-diastolic volume of the right ventricle had increased significantly in patients with SDB (n = 27) versus those without (n = 25) (mean±sd 14±23% versus 0±17%, p = 0.020). Multivariable linear regression analysis accounting for age, sex, body mass index, smoking, left ventricular mass and left ventricular end-systolic volume showed that the apnoea-hypopnoea index was significantly associated with right ventricular end-diastolic volume (B-coefficient 0.315 (95% CI 0.013-0.617); p = 0.041). From baseline to 12 weeks, right atrial diastolic area increased more in patients with SDB (2.9±3.7 cm(2) versus 1.0±2.4 cm(2), p = 0.038; when adjusted for left ventricular end systolic volume, p = 0.166). SDB diagnosed shortly after AMI predicts an increase of right ventricular end-diastolic volume and possibly right atrial area within the following 12 weeks. Thus, SDB may contribute to enlargement of the right heart after AMI.
    No preview · Article · Oct 2014 · European Respiratory Journal
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    ABSTRACT: Background: Knowledge about the molecular pathomechanisms of sarcopenia is still sparse, especially with regard to nutritional risk factors and the subtype of sarcopenic obesity. Objective: The aim of this study was to characterize diet-induced and age-related changes on the quality and quantity of the quadriceps muscle in a rat model of sarcopenia by different magnetic resonance (MR) techniques. Methods: A total of 36 6-month-old male Sprague-Dawley rats were randomly subdivided into 2 groups and received either a high-fat diet (HFD) or a control diet (CD). At the age of 16 months, 15 HFD and 18 CD rats underwent MR at 1.5 T. T1-weighted images as well as T2 relaxation time maps were acquired perpendicular to the long axis of the quadriceps muscles. Maximum cross-sectional area (CSA) of the quadriceps muscle was measured on T1-weighted images, and T2 relaxation times of muscle were assessed in a region without visible intramuscular fat (T2lean muscle) and across the complete CSA (T2muscle). Furthermore, (1)H-MR spectroscopy was performed to evaluate the relative lipid content of the quadriceps muscles. These measurements were repeated 5 months later in the surviving 8 HFD and 14 CD rats. Results: HFD rats revealed significantly decreased CSA and CSA per body weight (BW) as well as prolonged T2 relaxation times of muscle. A higher weight gain (upper tertile during the first 6 months of diet in CD rats) resulted in a significant change of T2muscle, but had no relevant impact on CSA. Advancing age up to 21 months led to significantly decreased BW, CSA and CSA/BW, significantly prolonged T2muscle and T2lean muscle and enlarged lipid content in the quadriceps muscle. Conclusions: In an experimental setting a chronically fat-enriched diet was shown to have a relevant and age-associated influence on both muscle quantity and quality. By translational means the employed MR techniques give rise to the possibility of an early detection and noninvasive quantification of sarcopenia in humans, which is highly relevant for the field of geriatrics. © 2014 S. Karger AG, Basel.
    No preview · Article · Jun 2014 · Gerontology
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    ABSTRACT: Objective: In patients with acute necrotizing pancreatitis, we analyzed whether laboratory and clinical findings determined in the early phase of disease and morphologic features on contrast-enhanced CT (CECT) at the beginning of the late phase of disease are helpful in predicting patient outcome and whether CECT findings provide additional information in establishing prognosis compared with the laboratory and clinical findings. Materials and methods: A retrospective analysis of 99 patients with acute necrotizing pancreatitis was performed. Four laboratory variables (albumin, calcium, C-reactive protein, WBC count) and three clinical variables (Acute Physiology, Age, Chronic Health Evaluation [APACHE] II score; Simplified Acute Physiology Score [SAPS] II; persistent organ failure) were assessed. Five morphologic features on CECT including Balthazar grade and CT severity index were reviewed. The endpoints of patient outcome were peripancreatic or pancreatic infection, need for intervention, duration of organ failure, ICU and hospital stays, and death. Based on receiver operating characteristic curve analysis for infection, high-and low-risk groups for each prognostic variable were calculated and univariable and multivariable Cox regression analyses were carried out. Results: In our study population of 99 patients (63 men, 36 women; median age, 52 years; age range, 18-84 years), 25 patients (25%) developed infection, 42 patients (42%) experienced organ failure, and 12 patients (12%) died. Regarding the laboratory and clinical variables, albumin level, APACHE II score, and particularly persistent organ failure were the strongest independent predictors of patient outcome. Regarding the imaging variables, Balthazar grade and a morphologic feature that takes the distribution of intrapancreatic necrosis into account were the strongest independent predictors. In the multivariable analysis of all studied variables, imaging variables were independent and strong predictors of patient outcome and provided additional information in establishing prognosis compared with clinical and laboratory findings. Conclusion: In patients with suspected or proven acute necrotizing pancreatitis, performing CECT at the beginning of the late phase of disease is recommended to identify patients at increased risk for adverse outcomes.
    No preview · Article · Jun 2014 · American Journal of Roentgenology
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    ABSTRACT: The increasing availability of computed tomography has meant that the number of incidentally detected solitary pulmonary nodules (SPN) has greatly increased in recent years. A reasonable management of these SPN is necessary in order to firstly be able to detect malignant lesions early on and secondly to avoid upsetting the patient unnecessarily or carrying out further stressful diagnostic procedures. This review article shows how the dignity of SPNs can be estimated and based on this how the management can be accomplished taking established guidelines into consideration.
    Full-text · Article · May 2014 · Der Radiologe

  • No preview · Article · Nov 2013 · European Heart Journal Cardiovascular Imaging
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    ABSTRACT: Sleep-disordered breathing (SDB) may be a risk factor for expansion of infarct size early after acute myocardial infarction (MI) by exposing the heart to repetitive oxygen desaturations and increased cardiac afterload. The objective of this study was to assess the impact of SDB on myocardial salvage and infarct size within 3 months after acute MI. Patients with acute MI and percutaneous coronary intervention were enrolled in this prospective observational study. All patients underwent cardiovascular magnetic resonance (CMR) to define salvaged myocardium and infarct size within three to five days and at 3 months after acute MI. Patients were stratified according to apnoea-hypopnoea index (AHI) assessed by polysomnography at baseline into those with (AHI ≥15/h) and without (AHI <15/h) SDB. Of the 56 patients included, 29 (52%) had SDB. The area at risk between both groups was similar (40 ± 12% vs. 40 ± 14%, P = 0.925). Patients with SDB had significantly less salvaged myocardium (myocardial salvage index 52% vs. 77%, P < 0.001), smaller reduction in infarct size (0.3% vs. 6.5%, P < 0.001) within 3 months after acute MI, a larger final infarct size (23% vs. 12%, P < 0.001), and a lower final left ventricular ejection fraction (48% vs. 54%, P = 0.023). In a multivariate analysis, including established risk factors for large MI, AHI was independently associated with less myocardial salvage and a larger infarct size 3 months after acute MI. Sleep-disordered breathing was associated with less myocardial salvage and a smaller reduction in infarct size. These findings suggest a contribution of SDB to impaired healing of MI.
    No preview · Article · Oct 2013 · European Heart Journal
  • Florian Poschenrieder · Christian Schulz · Okka Wilkea Hamer
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    ABSTRACT: Case Report. German Language. No abstract available.
    No preview · Article · Aug 2013 · RöFo - Fortschritte auf dem Gebiet der R
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    ABSTRACT: AimsWe investigated predictors of left atrial volume reduction (LAVR) in patients with atrial fibrillation (AF) undergoing AF ablation.Methods and resultsSixty patients with AF underwent pulmonary vein isolation (PVI) using a pulmonary vein ablation catheter (PVAC). All patients underwent cardiac imaging by computed tomography or magnetic resonance imaging to determine LAV 1 day before and 140 ± 9.5 days after PVI. Clinical follow-up and 72 h electrocardiogram Holter monitoring were performed 1, 3, and 6 months after ablation, and every 6 months thereafter. Significant LAVR (n = 60, 89.3 ± 3.9 vs. 79.5 ± 3.6 mL, P < 0.0001) was shown for the study group as a whole, caused particularly by the subgroup of patients with ablation success (n = 45, 85.2 ± 4.6 vs. 72.5 ± 3.7 mL, P < 0.0001). In addition, significant LAVR was shown for patients with lone AF (n = 25, 88.8 ± 6.8 vs. 72.7 ± 5.3 mL, P < 0.0001), but not for patients with AF and concomitant arterial hypertension (n = 32, 89 ± 4.8 vs. 86.7 ± 5 mL, P = 0.3), coronary artery disease (n = 12, 91.6 ± 7.8 vs. 89.1 ± 7.8 mL, P = 0.26), or left ventricular hypertrophy (n = 10, 86.3 ± 5.5 vs. 83.1 ± 5.3 mL, P = 0.27). Multivariate analysis revealed absence of arterial hypertension, lone AF, ablation success, and initial LA enlargement as independent predictors for significant LAVR following ablation (each P < 0.05).Conclusion Based on the subgroup of patients with lone AF, PVI leads to a significant LAVR 4 months after the procedure, especially in patients with clinical success in terms of AF freedom. Comorbidities such as arterial hypertension may prevent this reverse atrial remodelling, despite AF freedom. Clinical implications need to be further elucidated.
    Full-text · Article · Jun 2013 · Europace
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    ABSTRACT: Background: The complex anatomy of the aortic annulus warrants the use of three dimensional (3D) modalities for prosthesis sizing in transcatheter aortic valve implantation (TAVI). Multislice computed tomography (MSCT) has been used for this purpose, but its use may be restricted because of contrast administration. 3D transesophageal echocardiography (3D-TEE) lacks this limitation and data on comparison with MSCT is scarce. We compared 3D-TEE with MSCT for prosthesis sizing in TAVI. Methods: Aortic annulus diameters in the sagittal and coronal plane and annulus areas in 3D-TEE and MSCT were compared in 57 patients undergoing TAVI. Final prosthesis size was left at the operator's discretion and the agreement with 3D-TEE and MSCT was calculated. Results: Sagittal diameters on 3D-TEE and MSCT correlated well (r=.754, p<.0001) and means were comparable (22.3±2.1 vs. 22.5±2.3 mm; p=0.2; mean difference: -0.3 mm [-3.3-2.8]). On 3D-TEE, coronal diameter and annulus area were significantly smaller (p<.0001 for both) with moderate correlation (r=0.454 and r=0.592). Interobserver variability was comparable for both modalities. TAVI was successful in all patients with no severe post-procedural insufficiency. Final prosthesis size was best predicted by sagittal annulus diameters in 84% and 79% by 3D-TEE and MSCT, respectively. Agreement between both modalities was 77%. Conclusions: Annulus diameters and areas for pre-procedural TAVI assessment by 3D-TEE are significantly smaller than MSCT with exception of sagittal diameters. Using sagittal diameters, both modalities predicted well final prosthesis size and excellent procedural results were obtained. 3D-TEE can thus be a useful alternative in patients with contraindications to MSCT.
    No preview · Article · May 2013 · International journal of cardiology
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    ABSTRACT: Background: Sleep-disordered breathing (SDB) may promote an increase in cardiac workload early after acute myocardial infarction (AMI). We tested the hypothesis that in the early phase after AMI, SDB is associated with increased 24-h arterial BP, heart rate (HR), and, thus, cardiac workload. Methods: In this prospective study, 55 consecutive patients with AMI and subsequent percutaneous coronary intervention (78% men; mean age, 54 ± 10 y; mean BMI, 28.3 ± 3.6 kg/m²; mean left ventricular ejection fraction [LVEF], 47% ± 8%) underwent polysomnography and 24-h ambulatory BP and heart rate monitoring within 5 days after MI. Cardiac workload was calculated as systolic BP multiplied by HR. The presence of SDB was defined as ≥ 10 apneas and hypopneas per hour of sleep. Results: Fifty-five percent of the patients had SDB, of which 40% was predominantly central in nature. Patients with SDB had higher 24-h HR and systolic and diastolic BP compared with those without SDB (115 vs 108 mm Hg, P = .029; 71 vs 67 mm Hg, P = .034; 69 vs 64 beats/min, P = .050, respectively). Use of antihypertensive medication and β-receptor blockers was similar in both groups. In a multivariate linear regression analysis, SDB was significantly associated with an increased 24-h cardiac workload (β-coefficient, 0.364; 95% CI, 0.071-0.657; P = .016), independently of age, sex, BMI, LVEF, and antihypertensive medication. Conclusion: Patients with AMI and SDB have significantly increased 24-h BP, HR, and cardiac workload. Treatment of SDB may be a valuable nonpharmacologic approach to lower cardiac workload in these patients.
    No preview · Article · May 2013 · Chest
  • OW Hamer · F Poschenrieder

    No preview · Article · Apr 2013 · RöFo - Fortschritte auf dem Gebiet der R
  • A Götz · M Brand · OW Hamer · C Stroszczynski · P Heiss

    No preview · Article · Apr 2013 · RöFo - Fortschritte auf dem Gebiet der R
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    ABSTRACT: Pulmonary hypertension (PH) often leads to dilatation of the pulmonary artery (PA), which can be measured on chest computed tomography (CT). While the predictive capability of PA dilatation is useful to distinguish PH (mean PA pressure ≥25 mmHg) from normal (mean PA pressure ≤ 20 mmHg), CT characteristics of borderline PH (mean PA pressure 21-24 mmHg) have not been described. We aimed to investigate whether patients with borderline PH already show PA dilatation and to assess the diagnostic accuracy of PA dilatation for borderline PH diagnosis. Between April 2003 and September 2008, consecutive symptomatic patients with a mean PA pressure below 25 mmHg on right heart catheterization who had a chest CT available were retrospectively included. PA diameters from chest CT were correlated with hemodynamic measurements and analyzed with respect to their accuracy of predicting borderline PH. Main PA diameters were significantly larger in 26 patients with borderline PH compared with 52 patients without PH (3.16 ± 0.53 vs. 2.78 ± 0.43 cm, P = 0.001). The main PA diameter on CT correlated with mean PA pressure (r = 0.496, P < 0.001) and pulmonary vascular resistance (r = 0.445, P < 0.001), and predicted borderline PH with sensitivity, specificity, negative and positive predictive values of 77%, 62%, 84%, and 50%, respectively, using a cutoff ≥2.9 cm. This first systematic investigation of CT parameters in symptomatic patients with mean PA pressures less than 25 mmHg could show that, even in patients with borderline PH, significant PA dilatation can be present, which was related to PA pressure and pulmonary vascular resistance. This can be useful for identification of patients with borderline PH for further study and to prompt further diagnostic work-up of possible underlying diseases.
    Full-text · Article · Apr 2013
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    ABSTRACT: We investigate the frequency of esophageal tissue injury (ETI) following ablation of atrial fibrillation (AF) using the pulmonary vein ablation catheter (PVAC) ascertained by esophageal endoscopy (ESE) and corresponding magnetic resonance imaging (MRI). A total of 41 patients with symptomatic AF presenting for pulmonary vein isolation (PVI) were included consecutively in two observational groups. Group A received MRI the day before and ESE plus MRI within 3–4 weeks following the ablation procedure using the PVAC. Group B received MRI the day before and ESE plus MRI within 2 days after PVI. MRI included T2-weighted and T1-weighted postcontrast with fat suppression (fs) and late-enhancement scans to demonstrate postprocedural edema and contrast enhancement of the esophageal wall. A total of 13 (32%) patients were enrolled in Group A (26 ± 11 days post-PVI), and 28 (68%) patients in Group B (2 ± 0.6 days post-PVI). ETI was found by ESE in one (2%) patient (Group B) and resolved under conservative therapy. Corresponding MRI showed a false negative result with no alterations of esophageal structures using T1-weighted, T2-weighted, and late enhancement scans. In addition, false positive results were demonstrated by late-enhancement MRI in five (12%) patients (three patients in Group A and two patients in Group B), which could not be verified by corresponding ESE. Endoluminal ETI is a rare but possible complication, which should be considered following PVAC procedures. MRI of the esophagus is currently not a reliable screening method due to false positive and negative findings compared to ESE.
    No preview · Article · Feb 2013 · Pacing and Clinical Electrophysiology
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    ABSTRACT: Obesity has been suggested as a risk factor for sarcopenia. However, the underlying pathogenic concept of sarcopenic obesity is mainly based on phenotypical data from clinical observation. The present pilot study describes a rodent animal model which opens up prospects to carry out translational research of sarcopenic obesity in an experimental setting. Starting with 2 months, male Wistar rats were fed with a diet containing either 25 en % (control diet, CD) versus 45 en % (high fat diet, HFD) of neutral fat. At the age of 20 and 23 months quadriceps muscles were examined in vivo by magnetic resonance techniques which revealed a positive correlation between muscular fat and body weight (r = 0.639) and a negative correlation between muscular fat content and muscle volume (r = -0.742). Expression and phosphorylation status of proteins within the PKB/Akt and AMPK-dependent signaling pathway were examined in muscles of the 24 month-old animals which significantly showed a 50 percent upregulation of Ser(473)P-PKB/Akt and a 90 % constitutive downregulation of S6K1 in the HFD rats. Notably, S6K1 is a key mediator for muscular protein biosynthesis with additional negative feedback on PKB/Akt. Furthermore, muscular expression of the mitochondrial key regulator PGC-1α in the aged HFD rats was only 25 % of that concurrent controls (p = 0.029). These explorative findings in the aging high-fat fed rat might serve as a firm starting point for controlled longitudinal observations in a larger animal cohort of both sexes studying the natural history of sarcopenic obesity.
    No preview · Article · Oct 2012 · Biogerontology

Publication Stats

981 Citations
312.79 Total Impact Points


  • 2002-2015
    • University Hospital Regensburg
      • • Klinik und Poliklinik für Innere Medizin I
      • • Institut für Röntgendiagnostik
      Ratisbon, Bavaria, Germany
  • 2001-2014
    • Universität Regensburg
      • • Department of Internal Medicine I
      • • Department of Internal Medicine II
      Ratisbon, Bavaria, Germany
  • 2005-2006
    • University of California, San Diego
      • Department of Pediatrics
      San Diego, California, United States