title: High-resolution TOF MR angiography at 4.7 Tesla for volumetric and morphologic evaluation of coiled aneurysm neck remnants in a rat model.
abstract: BACKGROUND
  Detection of morphologic and volumetric changes in aneurysm necks is important when evaluating the effects of endovascular devices for aneurysm occlusion.
  
  
  OBJECTIVE
  To optimize high-resolution 3D-TOF MRA at 4.7 T in order to achieve the best aneurysm-to-background contrast in experimental rat aneurysms, and to quantify the volume of the aneurysm neck by imaging.
  
  
  METHODS
  Saccular aneurysms in the abdominal aorta of rats were coiled with platinum coils. Tissue relaxation times were measured, and used in a mathematical simulation. To optimize 3D-TOF angiography, imaging parameters were varied within the range obtained from the simulations. Tissue contrast and contrast-to-noise ratio were measured from MR images. TOF images were compared to conventional spin echo and gradient echo images and to endoscopic and histological analyses.
  
  
  RESULTS
  Parameters yielding the best aneurysm-to-background contrast and contrast-to-noise ratio were determined. The agreement between the results from in vivo imaging and simulation was good. The optimized 3D-TOF MRA sequence (TR/TE/FA = 60 ms/6.6 ms/20°) had an isotropic voxel size of 117 µm, which enabled measurement of the aneurysm neck volume.
  
  
  CONCLUSIONS
  High-resolution 3D-TOF angiography enables non-invasive quantification of changes in neck remnants of endovascularly coiled experimental aneurysms. In this model innovations like bioactive coils can be accurately tested for their efficacy for aneurysm occlusion.
authors.affiliation: Neurosurgery Research Group, Biomedicum Helsinki, Finland. johan.marjamaa@hus.fi
authors.forename: Johan
authors.initials: J
authors.lastname: Marjamaa
authors.forename: Henrik
authors.initials: H
authors.lastname: Antell
authors.forename: Usama
authors.initials: U
authors.lastname: Abo-Ramadan
authors.forename: Juha A
authors.initials: JA
authors.lastname: Hernesniemi
authors.forename: Mika R
authors.initials: MR
authors.lastname: Niemelä
authors.forename: Marko
authors.initials: M
authors.lastname: Kangasniemi
mesh_terms: D000818:Animals; D017544:Aortic Aneurysm, Abdominal / Q000628:therapy*; D003198:Computer Simulation; D004195:Disease Models, Animal; D004621:Embolization, Therapeutic / Q000295:instrumentation*; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D018810:Magnetic Resonance Angiography / Q000379:methods*; D010984:Platinum; D051381:Rats
chemical_list: D010984:Platinum