title: 3D computerized occlusion rating of embolized experimental aneurysms using noninvasive 1.5T MR imaging.
abstract: OBJECTIVE
  For embolized cerebral aneurysms, the initial occlusion rate is the most powerful parameter to predict aneurysm rerupture and recanalization. However, the occlusion rate is only estimated subjectively in clinical routine. To minimize subjective bias, computer occlusion-rating (COR) was successfully validated for 2D images. To minimize the remaining inaccuracy of 2D-COR, COR was applied to 1.5T 3D MR imaging.
  
  
  METHODS
  Twelve experimental rabbit aneurysms were subjected to stent-assisted coil embolization followed by 2D DSA and 3D MR imaging. Subjective occlusion-rate (SOR) was estimated. Linear parameters (aneurysm length, neck width, parent vessel diameter) were measured on 2D DSA and 3D MR imaging. The occlusion rate was measured by contrast medium-based identification of the nonoccluded 2D area/3D volume in relation to the total aneurysm 2D area/3D volume. 2D and 3D parameters were statistically compared.
  
  
  RESULTS
  There were no limiting metallic artifacts by using 3D MR imaging. Linear parameters (millimeters) were nearly identical on 2D DSA and 3D MR imaging (aneurysm length: 7.5 ± 2.6 versus 7.4 ± 2.5, P = .2334; neck width: 3.8 ± 1.0 versus 3.7 ± 1.1, P = .6377; parent vessel diameter: 2.7 ± 0.6 versus 2.7 ± 0.5, P = .8438), proving the high accuracy of 3D MR imaging. COR measured on 3D MR imaging was considerably lower (61.8% ± 26.6%) compared with the following: 1) 2D-COR (65.6% ± 27.1%, P = .0537) and 2) 2D-SOR estimations (69.2% ± 27.4%, P = .002). These findings demonstrate unacceptable bias in the current clinical standard SOR estimations.
  
  
  CONCLUSIONS
  3D-COR of embolized aneurysms is easily feasible. Its accuracy is superior to that of the clinical standard 2D-SOR. The difference between 3D-COR and 2D-COR approached statistical significance. 3D-COR may add objectivity to the ability to stratify the risk of rerupture in embolized cerebral aneurysms.
authors.affiliation: Department of Neurosurgery, Kantonsspital Aarau, Aarau, Switzerland. camillo.sherif@meduniwien.ac.at
authors.forename: C
authors.initials: C
authors.lastname: Sherif
authors.forename: S
authors.initials: S
authors.lastname: Marbacher
authors.forename: J
authors.initials: J
authors.lastname: Fandino
authors.forename: S
authors.initials: S
authors.lastname: Erhardt
authors.forename: V
authors.initials: V
authors.lastname: Neuschmelting
authors.forename: M
authors.initials: M
authors.lastname: Killer
authors.forename: G
authors.initials: G
authors.lastname: Mach
authors.forename: L
authors.initials: L
authors.lastname: Remonda
mesh_terms: D000783:Aneurysm / Q000473:pathology* / Q000601:surgery*; D000818:Animals; D002340:Carotid Artery Diseases / Q000473:pathology* / Q000601:surgery*; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D011379:Prognosis; D011817:Rabbits; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome