title: Aneurysm wall thickness measurements of experimental aneurysms: in vivo high-field MR imaging versus direct microscopy.
abstract: BACKGROUND
  Thin cerebral aneurysm wall thickness (AWT) is connected to high aneurysm rupture risk. MR imaging of AWT leads to overestimations. The aim of the present study was to quantify MR inaccuracy by comparison with accurate light microscopic measurements.
  
  
  METHODS
  In 13 experimental microsurgical bifurcation aneurysms in rabbits, 3 Tesla (3 T)-MR imaging using contrast-enhanced T1 Flash sequences (resolution: 0.4 × 0.4 × 1.5 mm³) was performed. The aneurysms were retrieved immediately after MR acquisition, cut longitudinally, and calibrated photographs were obtained. AWT (dome, neck) and parent vessel thickness (PVT) were measured on the MR images and microscopic photographs by independent investigators. All parameters were statistically compared (Wilcoxon test, Spearman correlation).
  
  
  RESULTS
  AWT and PVT could be imaged and measured in all aneurysms with good quality. Comparison with the "real" light microscopic measurements showed a progressive tendency of MR AWT overestimation with smaller AWT: AWT at the dome (0.24 ± 0.06 mm vs. MR 0.30 ± 0.08 mm; p = 0.0078; R = 0.6125), AWT at the neck (0.25 ± 0.07 mm vs. MR 0.29 ± 0.07 mm; p = 0.0469; R = 0.7451), and PVT (0.46 ± 0.06 mm vs. MR 0.48 ± 0.06 mm; p = 0.5; R = 0.8568).
  
  
  CONCLUSIONS
  In this experimental setting, 3 T-MR imaging of cerebral AWT showed unacceptable inaccuracies only below the image resolution threshold. Theoretically, AWT for clinical usage could be classified in ranges, defined by the maximum image resolution.
authors.affiliation: Department of Neurosurgery, Krankenanstalt Rudolfstiftung, Juchgasse 25, A-1030, Wien, Vienna, Austria, camillo.sherif@cerebrovascular.at.
authors.forename: Camillo
authors.initials: C
authors.lastname: Sherif
authors.forename: Günther
authors.initials: G
authors.lastname: Kleinpeter
authors.forename: Michel
authors.initials: M
authors.lastname: Loyoddin
authors.forename: Georg
authors.initials: G
authors.lastname: Mach
authors.forename: Roberto
authors.initials: R
authors.lastname: Plasenzotti
authors.forename: Thomas
authors.initials: T
authors.lastname: Haider
authors.forename: Erwin
authors.initials: E
authors.lastname: Herbich
authors.forename: Martin
authors.initials: M
authors.lastname: Krssak
mesh_terms: D017542:Aneurysm, Ruptured / Q000473:pathology*; D000818:Animals; D002533:Cerebral Angiography / Q000379:methods; D002536:Cerebral Arteries / Q000473:pathology*; D004195:Disease Models, Animal; D021621:Imaging, Three-Dimensional / Q000379:methods; D002532:Intracranial Aneurysm / Q000473:pathology*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008853:Microscopy / Q000379:methods*; D011817:Rabbits; D012680:Sensitivity and Specificity