title: Quantification of cerebral volumes on MRI 6 months after aneurysmal subarachnoid hemorrhage.
abstract: OBJECTIVE
  MRI can be used to assess structural damage to the brain after aneurysmal subarachnoid hemorrhage. We tuned, validated, and applied k-Nearest Neighbor-based segmentation to quantify cerebral volumes on MRI 6 months after aneurysmal subarachnoid hemorrhage.
  
  
  METHODS
  After tuning, the accuracy of k-Nearest Neighbor-based segmentation was assessed with manual segmentations. Next, supratentorial cerebral parenchymal, peripheral cerebrospinal fluid, and lateral ventricular volumes of 55 patients were compared with those of 25 age- and sex-matched control subjects and related to clinical outcome (modified Rankin Scale).
  
  
  RESULTS
  k-Nearest Neighbor-based segmentation showed good agreement with manual segmentations. Compared with control subjects, patients had a larger lateral ventricular volume (difference: log-transformed values 0.54; 95% CI,0.33-0.75), smaller peripheral cerebrospinal fluid volume (-26 mL; 95% CI, -40 to -11), and similar cerebral parenchymal volume (2 mL; 95% CI, -10 to 15). In patients, parenchymal (median split; OR, 38.8; 95% CI, 4.6-329.0) and ventricular volumes (7.4; 95% CI, 1.6-33.5) correlated with functional outcome.
  
  
  CONCLUSIONS
  k-Nearest Neighbor-based segmentation provides accurate cerebral volume measurements after aneurysmal subarachnoid hemorrhage. In this proof-of-principle study of this volumetric technique, we demonstrated volume changes relative to controls, which correlated with functional outcome.
authors.affiliation: Image Sciences Institute, Department of Neurology and Neurosurgery, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, The Netherlands. J.deBresser@umcutrecht.nl
authors.forename: Jeroen
authors.initials: J
authors.lastname: de Bresser
authors.forename: Koen L
authors.initials: KL
authors.lastname: Vincken
authors.forename: Anne J
authors.initials: AJ
authors.lastname: Kaspers
authors.forename: Gabriel J E
authors.initials: GJ
authors.lastname: Rinkel
authors.forename: Max A
authors.initials: MA
authors.lastname: Viergever
authors.forename: Geert Jan
authors.initials: GJ
authors.lastname: Biessels
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology* / Q000503:physiopathology*; D016022:Case-Control Studies; D002555:Cerebrospinal Fluid; D054022:Cerebrum / Q000473:pathology / Q000503:physiopathology; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D020547:Lateral Ventricles / Q000473:pathology / Q000503:physiopathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D013345:Subarachnoid Hemorrhage / Q000175:diagnosis / Q000473:pathology* / Q000503:physiopathology; D013997:Time Factors