Simone Waerntges

Publications (4)5.84 Total impact

• Article: A new approach to assess intracranial white matter abnormalities in glaucoma patients: changes of fractional anisotropy detected by 3T diffusion tensor imaging.

  Tobias Engelhorn, Georg Michelson, Simone Waerntges, Susanne Hempel, Ahmed El-Rafei, Tobias Struffert, Arnd Doerfler
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  ABSTRACT: The aims of this study was to evaluate, using 3-T diffusion tensor imaging, changes of fractional anisotropy (FA) in the orbital and intracranial part of the optic nerve (ON), the optic chiasm, the lateral geniculate nucleus, and different parts of the optic radiation (OR) in patients with glaucoma compared to controls and to determine whether FA correlates with disease severity. Twenty patients with glaucoma and 22 age-matched controls were examined using 3-T diffusion tensor imaging. Regions of interest were positioned on the FA maps, and mean values were calculated for each ON, optic chiasm, lateral geniculate nucleus, and OR. Results were compared to those from controls and correlated with ON atrophy and reduced spatial-temporal contrast sensitivity of the retina. Compared to controls, FA in patients with glaucoma was significantly lower in the intracranial part of the ON (0.48 ± 0.15 vs 0.66 ± 0.12, P < .05) and in the OR (0.40 ± 0.16 to 0.48 ± 0.17 vs 0.53 ± 0.20 to 0.64 ± 0.11, P < .05). A high correlation between reduced FA in the intracranial ON and OR and ON atrophy and spatial-temporal contrast sensitivity of the retina was observed (r > 0.81). Otherwise, there was no significant difference in FA between patients with glaucoma and controls measured in the orbital part of the ON, optic chiasm, and lateral geniculate nucleus. Diffusion tensor imaging at 3 T allows robust FA measurements in the intracranial part of the ON and the OR. FA is significantly reduced in patients with glaucoma compared to controls, with a good correlation with established ophthalmologic examinations.
  Academic radiology 01/2012; 19(4):485-8. · 2.09 Impact Factor
• Source

  Available from: PubMed Central

  Article: Changes of radial diffusivity and fractional anisotropy in the optic nerve and optic radiation of glaucoma patients.

  Tobias Engelhorn, Georg Michelson, Simone Waerntges, Marlen Otto, Ahmed El-Rafei, Tobias Struffert, Arnd Doerfler
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  ABSTRACT: Purpose of this study was to evaluate with diffusion-tensor imaging (DTI) changes of radial diffusivity (RD) and fractional anisotropy (FA) in the optic nerve (ON) and optic radiation (OR) in glaucoma and to determine whether changes in RD and FA correlate with disease severity. Therefore, glaucoma patients and controls were examined using 3T. Regions of interest were positioned on RD and FA maps, and mean values were calculated for ON and OR and correlated with optic nerve atrophy and reduced spatial-temporal contrast sensitivity (STCS) of the retina. We found, that RD in glaucoma patients was significantly higher in the ON (0.74 ± 0.21 versus 0.58 ± 0.17·10(-3) mm(2) s(-1); P < 0.05) and OR (0.79 ± 0.23 versus 0.62 ± 0.14·10(-3) mm(2) s(-1); P < 0.05) compared to controls. Aside, FA was significantly decreased (0.48 ± 0.15 versus 0.66 ± 0.12 and 0.50 ± 0.20 versus 0.66 ± 0.11; P < 0.05). Hereby, correlation between changes in RD/FA and optic nerve atrophy/STCS was observed (r > 0.77). In conclusion, DTI at 3 Tesla allows robust RD and FA measurements in the ON and OR. Hereby, the extent of RD increase and FA decrease in glaucoma correlate with established ophthalmological examinations.
  TheScientificWorldJOURNAL 01/2012; 2012:849632. · 1.66 Impact Factor
• Article: Diffusion tensor imaging detects rarefaction of optic radiation in glaucoma patients.

  Tobias Engelhorn, Georg Michelson, Simone Waerntges, Tobias Struffert, Sultan Haider, Arnd Doerfler
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  ABSTRACT: Diffusion tensor imaging (DTI) can depict rarefaction of the optical fibres. Hence, we applied DTI to assess pathological changes of the optic radiation in glaucoma patients. Fifty glaucoma patients and 50 healthy age-matched controls were examined by a 3T high-field magnetic resonance scanner. Fiber tracts were volume rendered using a semiquantitative approach to assess rarefaction and results were correlated with the extent of optic nerve atrophy and reduced spatial-temporal contrast sensitivity of the retina using established ophthalmological examinations. Twenty-two glaucoma patients (44%) showed significant rarefaction of the optic radiation: the volume was reduced to 67 ± 16% compared with controls. Hereby, the glaucomatous optic nerve atrophy stage correlated with the presence of DTI-derived rarefied optic radiation (Kendall tau-b 0.272, P = .016). Aside, cerebral microangiopathy affecting the optic radiation was significantly higher among glaucoma patients compared to controls (10 patients compared with 2 patients, P < .05). In patients with glaucomatous optic nerve atrophy, there is anterograde and-most likely because of microangiopathic lesions within the optic radiation-retrograde transneuronal rarefaction of the optic radiation that can be assessed in vivo using DTI with good correlation to established ophthalmological examinations.
  Academic radiology 03/2011; 18(6):764-9. · 2.09 Impact Factor
• Source

  Available from: Joachim Hornegger

  Chapter: Automatic Segmentation of the Optic Radiation Using DTI in Healthy Subjects and Patients with Glaucoma

  Ahmed El-Rafei, Tobias Engelhorn, Simone Waerntges, Arnd Doerfler, Joachim Hornegger, Georg Michelson
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  ABSTRACT: The complexity of the diffusion tensor imaging (DTI) data and the interpersonal variability of the brain fiber structure make the identification of the fibers a difficult and time consuming task. In this work, an automated segmentation system of the optic radiation using DTI is proposed. The system is applicable to normal subjects and glaucoma patients. It is intended to aid future glaucoma studies. The automation of the system is based on utilizing physiological and anatomical information to produce robust initial estimates of the optic radiation. The estimated optic radiation initializes a statistical level set framework. The optic radiation is segmented by the surface evolution of the level set function. The system is tested using eighteen DTI-datasets of glaucoma patients and normal subjects. The segmentation results were compared to the manual segmentation performed by a physician experienced in neuroimaging and found to be in agreement with the known anatomy with 83% accuracy. The automation eliminates the necessity of medical experts’ intervention and facilitates studies with large number of subjects. KeywordsDiffusion tensor imaging (DTI)-Segmentation-Optic radiation-Glaucoma
  11/2010: pages 1-15;