title: MRI compatible head phantom for ultrasound surgery.
abstract: OBJECTIVE
  Develop a magnetic resonance imaging (MRI) compatible head phantom with acoustic attenuation closely matched to the human attenuation, and suitable for testing focused ultrasound surgery protocols.
  
  
  METHODS
  Images from an adult brain CT scan were used to segment the skull bone from adjacent cerebral tissue. The segmented model was manufactured in a 3-D printer using (Acrylonitrile Butadiene Styrene) ABS plastic. The cerebral tissue was mimicked by an agar-evaporated milk-silica gel (2% w/v-25% v/v-1.2% w/v) which was molded inside a skull model.
  
  
  RESULTS
  The measured attenuation of the ABS skull was 16 dB/cm MHz. The estimated attenuation coefficient of the gel replicating brain tissue was 0.6 dB/cm MHz. The estimated agar-silica gel's T1 and T2 relaxation times in a 1.5 Tesla magnetic field were 852 ms and 66 ms respectively. The effectiveness of the skull to reduce ultrasonic heating was demonstrated using MRI thermometry.
  
  
  CONCLUSIONS
  Due to growing interest in using MRI guided focused ultrasound (MRgFUS) for treating brain cancer and its application in sonothrombolysis, the proposed head phantom can be utilized as a very useful tool for evaluating ultrasonic protocols, thus minimizing the need for animal models and cadavers.
authors.affiliation: City University, London, UK.
authors.forename: Georgios
authors.initials: G
authors.lastname: Menikou
authors.affiliation: University Medical Center Freiburg, Radiology - Medical Physics, Freiburg, Germany.
authors.forename: Tetiana
authors.initials: T
authors.lastname: Dadakova
authors.affiliation: University Medical Center Freiburg, Radiology - Medical Physics, Freiburg, Germany.
authors.forename: Matt
authors.initials: M
authors.lastname: Pavlina
authors.affiliation: University Medical Center Freiburg, Radiology - Medical Physics, Freiburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Bock
authors.affiliation: Cyprus University of Technology, Limassol, Cyprus. Electronic address: cdamianou@cytanet.com.cy.
authors.forename: Christakis
authors.initials: C
authors.lastname: Damianou
mesh_terms: D000328:Adult; D001921:Brain / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008959:Models, Neurological; D019047:Phantoms, Imaging; D066330:Printing, Three-Dimensional; D011859:Radiography; D012886:Skull / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D025321:Surgery, Computer-Assisted / Q000379:methods*; D062125:Thermometry; D014464:Ultrasonic Therapy / Q000379:methods*; D014463:Ultrasonography
keywords: Brain; MRI; Ultrasound