title: Two methods for semi-automated quantification of changes in ventricular volume and their use in schizophrenia.
abstract: Two semi-automated methods for quantification of ventricular volume change from baseline and follow-up magnetic resonance imaging scans have been developed. Technique 1 employs direct segmentation of the ventricles from both the scans using thresholding and contour extraction. Technique 2 operates on difference images produced by voxel based intensity subtraction of the baseline from the registered follow-up images. Here, all voxels with intensities above a noise threshold and in a restricted area are monitored to compute volumetric changes. In phantom measurements the first technique was accurate to 0.0046%, the second to 0.167% of the phantom volume. Results from normal volunteers was that the average ventricular volume changed by 1.52% and 1.54% for images acquired within 9 months using techniques 1 and 2, respectively. With schizophrenic patients mean change of 10.78% and 9.43% were found employing the first and second procedures, respectively. All measurements agreed with a radiologist's visual grading of the changes. Robust, objective, fast, easy-to-use, and fairly accurate procedures have been developed and validated to quantify volumetric changes.
authors.affiliation: Picker Research Group, MRI Unit, Imperial College School of Medicine, Hammersmith Hospital, London, United Kingdom. nsaeed@rpms.ac.uk
authors.forename: N
authors.initials: N
authors.lastname: Saeed
authors.forename: B K
authors.initials: BK
authors.lastname: Puri
authors.forename: A
authors.initials: A
authors.lastname: Oatridge
authors.forename: J V
authors.initials: JV
authors.lastname: Hajnal
authors.forename: I R
authors.initials: IR
authors.lastname: Young
mesh_terms: D000328:Adult; D000465:Algorithms; D016477:Artifacts; D002552:Cerebral Ventricles / Q000473:pathology*; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D019047:Phantoms, Imaging; D012016:Reference Values; D012559:Schizophrenia / Q000175:diagnosis*; D013997:Time Factors