title: High Resolution Imaging of Viscoelastic Properties of Intracranial Tumours by Multi-Frequency Magnetic Resonance Elastography.
abstract: OBJECTIVE
  In recent years Magnetic Resonance Elastography (MRE) emerged into a clinically applicable imaging technique. It has been shown that MRE is capable of measuring global changes of the viscoelastic properties of cerebral tissue. The purpose of our study was to evaluate a spatially resolved three-dimensional multi-frequent MRE (3DMMRE) for assessment of the viscoelastic properties of intracranial tumours.
  
  
  METHODS
  A total of 27 patients (63 ± 13 years) were included. All examinations were performed on a 3.0 T scanner, using a modified phase-contrast echo planar imaging sequence. We used 7 vibration frequencies in the low acoustic range with a temporal resolution of 8 dynamics per wave cycle. Post-processing included multi-frequency dual elasto-visco (MDEV) inversion to generate high-resolution maps of the magnitude |G*| and the phase angle φ of the complex valued shear modulus.
  
  
  RESULTS
  The tumour entities included in this study were: glioblastoma (n = 11), anaplastic astrocytoma (n = 3), meningioma (n = 7), cerebral metastasis (n = 5) and intracerebral abscess formation (n = 1). Primary brain tumours and cerebral metastases were not distinguishable in terms of |G*| and φ. Glioblastoma presented the largest range of |G*| values and a trend was delineable that glioblastoma were slightly softer than WHO grade III tumours. In terms of φ, meningiomas were clearly distinguishable from all other entities.
  
  
  CONCLUSIONS
  In this pilot study, while analysing the viscoelastic constants of various intracranial tumour entities with an improved spatial resolution, it was possible to characterize intracranial tumours by their mechanical properties. We were able to clearly delineate meningiomas from intraaxial tumours, while for the latter group an overlap remains in viscoelastic terms.
authors.affiliation: Department of Neuroradiology, University of Leipzig, Liebigstr. 20, 04103, Leipzig, Germany. martin.reiss-zimmermann@medizin.uni-leipzig.de.
authors.forename: M
authors.initials: M
authors.lastname: Reiss-Zimmermann
authors.affiliation: Department of Radiology, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany.
authors.forename: K-J
authors.initials: KJ
authors.lastname: Streitberger
authors.affiliation: Department of Radiology, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Sack
authors.affiliation: Department of Radiology, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Braun
authors.affiliation: Department of Neurosurgery, University of Leipzig, Liebigstr. 20, 04103, Leipzig, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Arlt
authors.affiliation: Department of Neuroradiology, University of Leipzig, Liebigstr. 20, 04103, Leipzig, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Fritzsch
authors.affiliation: Department of Neuroradiology, University of Leipzig, Liebigstr. 20, 04103, Leipzig, Germany.
authors.forename: K-T
authors.initials: KT
authors.lastname: Hoffmann
mesh_terms: D001932:Brain Neoplasms / Q000473:pathology* / Q000503:physiopathology*; D003198:Computer Simulation; D003937:Diagnosis, Differential; D055119:Elastic Modulus; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006244:Hardness; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D010865:Pilot Projects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D014783:Viscosity
keywords: Brain tumours; MR elastography; Meningioma; Multi-frequency; Viscoelastic properties