title: Software output from semi-automated planimetry can underestimate intracerebral haemorrhage and peri-haematomal oedema volumes by up to 41.
abstract: BACKGROUND
  Haematoma and oedema size determines outcome after intracerebral haemorrhage (ICH), with each added 10 % volume increasing mortality by 5 %. We assessed the reliability of semi-automated computed tomography planimetry using Analyze and Osirix softwares.
  
  
  METHODS
  We randomly selected 100 scans from 1329 ICH patients from two centres. We used Hounsfield Unit thresholds of 5-33 for oedema and 44-100 for ICH. Three raters segmented all scans using both softwares and 20 scans repeated for intra-rater reliability and segmentation timing. Volumes reported by Analyze and Osirix were compared to volume estimates calculated using the best practice method, taking effective individual slice thickness, i.e. voxel depth, into account.
  
  
  RESULTS
  There was excellent overall inter-rater, intra-rater and inter-software reliability, all intraclass correlation coefficients >0.918. Analyze and Osirix produced similar haematoma (mean difference: Analyze - Osirix = 1.5 ± 5.2 mL, 6 %, p ≤ 0.001) and oedema volumes (-0.6 ± 12.6 mL, -3 %, p = 0.377). Compared to a best practice approach to volume calculation, the automated haematoma volume output was 2.6 mL (-11 %) too small with Analyze and 4.0 mL (-18 %) too small with Osirix, whilst the oedema volumes were 2.5 mL (-12 %) and 5.5 mL (-25 %) too small, correspondingly. In scans with variable slice thickness, the volume underestimations were larger, -29%/-36 % for ICH and -29 %/-41 % for oedema. Mean segmentation times were 6:53 ± 4:02 min with Analyze and 9:06 ± 5:24 min with Osirix (p < 0.001).
  
  
  CONCLUSIONS
  Our results demonstrate that the method used to determine voxel depth can influence the final volume output markedly. Results of clinical and collaborative studies need to be considered in the context of these methodological differences.
authors.affiliation: Department of Medicine at the Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Teddy Y
authors.initials: TY
authors.lastname: Wu
authors.affiliation: Centre for Vascular and Stroke Research, Manchester Academic Health Sciences Centre, Salford Royal Hospital Trust, University of Manchester, Manchester, UK.
authors.forename: Oluwaseun
authors.initials: O
authors.lastname: Sobowale
authors.affiliation: Centre for Vascular and Stroke Research, Manchester Academic Health Sciences Centre, Salford Royal Hospital Trust, University of Manchester, Manchester, UK.
authors.forename: Robert
authors.initials: R
authors.lastname: Hurford
authors.affiliation: Department of Radiology, the Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Gagan
authors.initials: G
authors.lastname: Sharma
authors.affiliation: Stanford Stroke Center, Stanford University, Palo Alto, CA, USA.
authors.forename: Søren
authors.initials: S
authors.lastname: Christensen
authors.affiliation: Department of Medicine at the Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Nawaf
authors.initials: N
authors.lastname: Yassi
authors.affiliation: Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.|Department of Neurology, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors.forename: Turgut
authors.initials: T
authors.lastname: Tatlisumak
authors.affiliation: Department of Radiology, the Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Patricia M
authors.initials: PM
authors.lastname: Desmond
authors.affiliation: Department of Medicine at the Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Bruce C V
authors.initials: BC
authors.lastname: Campbell
authors.affiliation: Department of Medicine at the Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Davis
authors.affiliation: Centre for Vascular and Stroke Research, Manchester Academic Health Sciences Centre, Salford Royal Hospital Trust, University of Manchester, Manchester, UK.
authors.forename: Adrian R
authors.initials: AR
authors.lastname: Parry-Jones
authors.affiliation: Department of Medicine at the Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia. atte.meretoja@unimelb.edu.au.|Department of Neurology, Helsinki University Hospital, PK Admin, Haartmaninkatu 4E, P.O. Box 220, 00029 HUS, Helsinki, Finland. atte.meretoja@unimelb.edu.au.
authors.forename: Atte
authors.initials: A
authors.lastname: Meretoja
mesh_terms: D000368:Aged; D000465:Algorithms; D001929:Brain Edema / Q000150:complications / Q000000981:diagnostic imaging* / Q000473:pathology; D002543:Cerebral Hemorrhage / Q000150:complications / Q000000981:diagnostic imaging* / Q000473:pathology; D005188:False Negative Reactions; D005260:Female; D006407:Hematoma, Epidural, Cranial / Q000150:complications / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D007089:Image Enhancement; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D015588:Observer Variation; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Intracerebral haemorrhage; Oedema; Planimetry; Reliability; Validation