M Galanski

Hannover Medical School, Hanover, Lower Saxony, Germany

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Publications (278)694.04 Total impact

  • First Russian Edition 01/2014; Thieme.
  • H. Shin, G. Stamm, D. Högemann, M. Galanski
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    ABSTRACT: Die Erstellung eines Modells für die virtuelle Realität untergliedert sich in mehrere Einzelschritte. Ziel der Datenakquisition ist die Gewinnung eines annähernd isotropen (gleiche Auflösung in allen 3 Raumachsen), rauscharmen Datensatzes. Eine annähernde Isotropie kann durch geeignete Wahl der Scanparameter erreicht werden. Für die Rohdatenrekonstruktion verbietet sich die Anwendung von hochauflösenden Rekonstruktionsalgorithmen aufgrund des erhöhten Rauschens. Die nachfolgende Bildverarbeitung kann eine fehlende Isotropie durch Interpolation zumindest rechnerisch annähern. Eine weitere Rauschunterdrückung wird durch den Einsatz von Filtern erzielt. Zusätzlich kann durch Bildverarbeitungsoperatoren der Kontrast zwischen dem zu segmentierenden Objekt und dem Hintergrund verstärkt werden. Die richtige Wahl des Segmentationsverfahrens und der Editierwerkzeuge ist entscheidend für eine genaue Segmentation mit geringem Interaktionsaufwand. Vor der Visualisierung kann durch Konturglättung (formbasierte oder morphologische Interpolation, Polygonreduktion von Drahtgittermodellen ) ein optisch ansprechendes 3D-Modell angefertigt werden. Creating models for virtual reality subdivides into several steps. The aim of the data acquisition is the extraction of nearly isotropic (same solution in all three axes) data sets with low noise content. An approximate isotropy can be achieved by suitable choice of scan parameters. For raw data reconstruction, the application of high-resolution reconstruction algorithms is prohibited due to increased noise. A missing isotropy can computationally be approximated by interpolation. Further noise suppression is achieved by applying filters. Additionally, the contrast of the object for segmentation can be increased by image processing operators. The correct choice of the segmentation method and the editing tools is essential for a precise segmentation with minimal user interaction. Prior to visualization, smoothing the shape of the segmented model (shape-based or morphological interpolation, polygon reduction of wire frame model) further improves the visual appearance of the 3D model.
    Der Radiologe 04/2012; 40(3):304-312. · 0.41 Impact Factor
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    ABSTRACT: More than 100,000 chemicals are in use but have not been tested for their safety. To overcome limitations in the cancer bioassay several alternative testing strategies are explored. The inability to monitor non-invasively onset and progression of disease limits, however, the value of current testing strategies. Here, we report the application of in vivo imaging to a c-Myc transgenic mouse model of liver cancer for the development of a short-term cancer bioassay. μCT and ¹⁸F-FDG μPET were used to detect and quantify tumor lesions after treatment with the genotoxic carcinogen NDEA, the tumor promoting agent BHT or the hepatotoxin paracetamol. Tumor growth was investigated between the ages of 4 to 8.5 months and contrast-enhanced μCT imaging detected liver lesions as well as metastatic spread with high sensitivity and accuracy as confirmed by histopathology. Significant differences in the onset of tumor growth, tumor load and glucose metabolism were observed when the NDEA treatment group was compared with any of the other treatment groups. NDEA treatment of c-Myc transgenic mice significantly accelerated tumor growth and caused metastatic spread of HCC in to lung but this treatment also induced primary lung cancer growth. In contrast, BHT and paracetamol did not promote hepatocarcinogenesis. The present study evidences the accuracy of in vivo imaging in defining tumor growth, tumor load, lesion number and metastatic spread. Consequently, the application of in vivo imaging techniques to transgenic animal models may possibly enable short-term cancer bioassays to significantly improve hazard identification and follow-up examinations of different organs by non-invasive methods.
    PLoS ONE 02/2012; 7(2):e30432. · 3.53 Impact Factor
  • 01/2012; Lavoisier.
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    ABSTRACT: To evaluate MR diffusion tensor imaging (DTI) as non-invasive diagnostic tool for detection of acute and chronic allograft dysfunction and changes of organ microstructure. 15 kidney transplanted patients with allograft dysfunction and 14 healthy volunteers were examined using a fat-saturated echo-planar DTI-sequence at 1.5 T (6 diffusion directions, b = 0, 600 s/mm²). Mean apparent diffusion coefficient (ADC) and mean fractional anisotropy (FA) were calculated separately for the cortex and for the medulla and compared between healthy and transplanted kidneys. Furthermore, the correlation between diffusion parameters and estimated GFR was determined. The ADC in the cortex and in the medulla were lower in transplanted than in healthy kidneys (p < 0.01). Differences were more distinct for FA, especially in the renal medulla, with a significant reduction in allografts (p < 0.001). Furthermore, in transplanted patients a correlation between mean FA in the medulla and estimated GFR was observed (r = 0.72, p < 0.01). Tractography visualized changes in renal microstructure in patients with impaired allograft function. Changes in allograft function and microstructure can be detected and quantified using DTI. However, to prove the value of DTI for standard clinical application especially correlation of imaging findings and biopsy results is necessary.
    European Radiology 06/2011; 21(11):2427-33. · 4.34 Impact Factor
  • 05/2011; Editorial Médica Panamericana.
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    ABSTRACT: We report on a patient with terminal renal insufficiency undergoing hemodialysis since four months. Imaging studies showed complete renal artery occlusion of a single kidney with collateral perfusion. Interventional recanalization of the renal artery was successful with a drop of serum creatinine from 1138 to 163 mol/l sparing the patient from further hemodialysis.
    Journal of Radiology Case Reports 05/2011; 5(5):19-23.
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    ABSTRACT: Up to now, due to a better image quality, for brain imaging the substantially slower sequential examination mode has been preferred during CT in polytraumatized patients. We aimed to re-evaluate modern ultrafast 64-row spiral CT regarding image quality in brain imaging of polytraumatized patients. In 30 polytraumatized patients, both 64-row spiral and sequential CT of the brain were performed within 24h. Retrospectively, two radiologists subjectively evaluated the delineation of the internal capsule, the pons, the medial rectus muscle of the orbita, the differentiation of grey/white matter, and the extent of artifacts at the inner skull. Image noise was also evaluated objectively. Statistics were performed using Cohen's kappa and a two-sided t-test. Perfect or clear agreements were noted regarding the delineation of the inner skull, the medial rectus muscle, the internal capsule, and grey/white matter differentiation. Due to beam hardening artifacts at the level of the pons, no agreement and no superiority of one of the CT-methods was noted. No differences were obtained regarding the objective evaluation of image noise. Image quality is generally equivalent. Since 64-row spiral CT can substantially save examination time we recommend to perform a spiral examination of the brain in polytraumatized patients.
    European journal of radiology 02/2011; 81(4):789-93. · 2.65 Impact Factor
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    ABSTRACT: Micro-computed tomography (CT) allows high-resolution imaging of the chest in mice for small animal research with a significant radiation dose applied. To report on measurement of the applied radiation dose using different scan protocols in micro-CT of the chest in mice. Repetitive dose measurements were performed for four different micro-CT protocols (with/without respiratory gating) and for micro-CT fluoroscopy used for chest imaging. Measurements were carried out using thermoluminescence dosimeters (TLD) in mouse cadavers and in a PMMA phantom allowing measurement of the radiation dose in the direct path of rays and assessment of scattered radiation. The dose measured inside and outside the chests of the cadavers varied between 190 und 210 mGy, respectively. The expected mean doses in mice in the direct path of rays for the four examined micro-CT protocols varied between 170 and 280 mGy. The mean values for 1 and 5 minutes of fluoroscopy were 17 mGy and 105 mGy, respectively. The measured dose values are similar to the dose values for micro-CT of the chest reported so far. A relevant dose can be delivered by micro-CT of the chest, which could possibly interact with small animal studies. Therefore, the applied dose for a specific protocol should be known and adverse radiation effects be considered.
    Acta Radiologica 02/2011; 52(1):75-80. · 1.35 Impact Factor
  • 01/2011; CIC Edizioni Internazionali.
  • First Japanese Edition 01/2011; Medical Sciences International Ltd., ISBN: 978-4-89592-690-4
  • 01/2011; Artmed.
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    ABSTRACT: Preclinical and clinical topics are often separated in medical education. For example, surgery and radiology are often taught much later than anatomy. The aim of this study was to establish and to evaluate an interdisciplinary course combining these closely related subjects to enhance medical comprehension. Two tutorials each lasting one term were offered to second year medical students, in which clinical topics were implemented linking anatomy to surgical and radiological knowledge. A questionnaire was used to evaluate the success of this approach. The motivation of the students was above average and the practical work was done accurately. The students confirmed that the course improved anatomical comprehension (>95%) and that the learned matters were relevant for their future (90%). Furthermore, interest in the subjects was higher after the course (>85%). Critical suggestions were to extend the course and to include more topics. A mix of surgery, radiology and anatomy is a teaching concept, which leads to high acceptance and interest in medical students.
    Anatomia Clinica 10/2010; 32(8):791-5. · 1.33 Impact Factor
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    ABSTRACT: To develop and evaluate a novel algorithm for semiautomated segmentation and volumetry of pleural effusions in multidetector computed tomography (MDCT) datasets. A seven-step algorithm for semiautomated segmentation of pleural effusions in MDCT datasets was developed, mainly using algorithms from the ITK image processing library. Semiautomated segmentation of pleural effusions was performed in 40 MDCT datasets of the chest (males = 22, females = 18, mean age: 56.7 +/- 19.3 years). The accuracy of the semiautomated segmentation as compared with a manual segmentation approach was quantified based on the differences of the segmented volumes, the degree of over-/undersegmentation, and the Hausdorff distance. The time needed for the semiautomated and the manual segmentation process were recorded and compared. The mean volume of the pleural effusions was 557.30 mL (+/- 477.27 mL) for the semiautomated and 553.19 (+/- 473.49 mL) for the manual segmentation. The difference was not statistically significant (Student t-test, P = .133). Regression analysis confirmed a strong relationship between the semiautomated algorithm and the gold standard (r(2) = 0.998). Mean overlap of the segmented areas was 79% (+/- 9.3%) over all datasets with moderate oversegmentation (22% +/- 9.3%) and undersegmentation (21% +/- 9.7%). The mean Hausdorff distance was 17.2 mm (+/- 8.35 mm). The mean duration of the semiautomated segmentation process with user interaction was 8.4 minutes (+/- 2.6 minutes) as compared to 32.9 minutes (+/- 17.4 minutes) for manual segmentation. The semiautomated algorithm for segmentation and volumetry of pleural effusions in MDCT datasets shows a high diagnostic accuracy when compared with manual segmentation.
    Academic radiology 07/2010; 17(7):841-8. · 2.09 Impact Factor
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    ABSTRACT: To test the null hypothesis that there is no quantitative or qualitative difference between respiratory-triggered three-dimensional (3D) T2-weighted magnetic resonance (MR) cholangiography performed before or after administration of gadoxetate disodium. For this retrospective HIPAA-compliant dual-center study, institutional review board approval was obtained, and a waiver of informed consent was granted. Between July and December 2008, 60 patients (age range, 18-82 years) who were referred for liver MR imaging with gadoxetate disodium underwent respiratory-triggered 3D MR cholangiography before and immediately after completion of portal venous phase contrast material-enhanced T1-weighted MR imaging. Quantitative signal-to-noise ratio (SNR) measurements were obtained in the extrahepatic biliary tract in both MR cholangiographic data sets in each patient. Qualitative assessment was performed by four readers with a four-point scale to assess the depiction of extra- and intrahepatic ducts up to the third order. Statistical analysis consisted of a one-sided Wilcoxon signed rank test, with a P value of less than .05 indicating a significant difference. There was a significant decrease in mean SNR in the MR cholangiographic data set after injection of gadoxetate disodium. SNR was 96 + or - 50 [standard deviation] and 78 + or - 47 before and after contrast media administration, respectively (P < .0001). For all readers, qualitative differences were most obvious in the depiction of the common bile duct and second- and third-order biliary branches, with the precontrast MR cholangiographic data sets being preferred (P < .0001). Precontrast data sets were also significantly preferred in the assessment of the right and left hepatic ducts by all readers. Gadoxetate disodium adversely affects respiratory-triggered 3D MR cholangiography, both qualitatively and quantitatively. We recommend that such a sequence be performed before injection of gadoxetate disodium.
    Radiology 05/2010; 255(2):451-8. · 6.21 Impact Factor
  • RöFo - Fortschritte auf dem Gebiet der R 03/2010; 182. · 1.96 Impact Factor
  • RöFo - Fortschritte auf dem Gebiet der R 03/2010; 182. · 1.96 Impact Factor
  • RöFo - Fortschritte auf dem Gebiet der R 03/2010; 182. · 1.96 Impact Factor
  • Christian von Falck, Michael Galanski, Hoen-Oh Shin
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    ABSTRACT: Current multidetector computed tomography (CT) scanners allow volumetric data acquisition with thin-section collimations and overlapping section reconstructions. The resultant nearly isotropic data sets help minimize partial-volume averaging effects and are ideal for two- and three-dimensional postprocessing and software-assisted lesion detection and quantification. However, the section thickness, image noise, and radiation dose are closely related, and when one parameter must be altered to suit the clinical setting, the others may be affected. When the clinical purpose demands both high spatial resolution and low image noise (eg, for the detection of hypoattenuating lesions in organs such as the kidneys and liver), the necessary trade-off--an increase in the radiation dose to the patient--may be unacceptable. The application of a sliding-thin-slab averaging algorithm during image postprocessing and review helps overcome this limitation by reconstructing thicker sections with lower noise levels from thin-section data obtained with dose-saving protocols. In principle, a high noise level is acceptable in the initial reconstruction of the CT volume data set. During image review at the workstation, the section thickness can be interactively increased to minimize image noise and improve lesion detectability. The combination of thin-section scanning with thick-section display allows routine volumetric imaging without a general increase in radiation dose or a reduction in the detectability of low-contrast lesions. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.302096007/-/DC1.
    Radiographics 03/2010; 30(2):317-26. · 2.73 Impact Factor
  • H Shin, A Reichelt, H Essig, M Galanski
    RöFo - Fortschritte auf dem Gebiet der R 03/2010; 182. · 1.96 Impact Factor

Publication Stats

3k Citations
694.04 Total Impact Points


  • 1988–2012
    • Hannover Medical School
      • • Department of Cardiothoracic, Transplantation and Vascular Surgery (HTTG)
      • • Department of Gastroenterology, Hepatology and Endocrinology
      • • Institute for Radiology
      Hanover, Lower Saxony, Germany
  • 2008
    • Klinikum Oldenburg
      Oldenburg, Lower Saxony, Germany
  • 2007
    • MVZ Zentrum für diagnostische Radiologie und Nuklearmedizin Braunschweig GmbH
      Brunswyck, Lower Saxony, Germany
  • 2005
    • University of Cologne
      Köln, North Rhine-Westphalia, Germany
  • 2003
    • Bundesamt für Strahlenschutz, BfS
      Brunswyck, Lower Saxony, Germany
  • 2002
    • Franziskus Hospital
      Linz, Rheinland-Pfalz, Germany
  • 2001
    • Massachusetts General Hospital
      Boston, Massachusetts, United States