title: Phase-Contrast MRI CSF Flow Measurements for the Diagnosis of Normal-Pressure Hydrocephalus: Observer Agreement of Velocity Versus Volume Parameters.
abstract: OBJECTIVE
  Manual segmentation of the aqueduct for CSF flow analysis may induce measurement variability. The aim of our study was to assess observer agreement of manual segmentation and to compare the repeatability and accuracy of different flow parameters in differentiating normal-pressure hydrocephalus (NPH) from brain atrophy.
  
  
  METHODS
  Thirty-two subjects were included and were divided into three groups: control, NPH, and brain atrophy. Subjects underwent phase-contrast MRI. Quantitative analysis of aqueductal CSF flow using manual ROI placement was performed by two independent readers. Reader 1 repeated measurements 3 months after the first session to assess interobserver and intraobserver agreement. Intraclass correlation coefficients (ICCs), within-subject SD, and repeatability were calculated. Peak systolic velocity (PSV), peak mean velocity, and aqueductal CSF stroke volume, which we refer to as "stroke volume," were recorded and compared between the three patient groups. The ROC curves of diagnostic accuracy for NPH were compared.
  
  
  RESULTS
  PSV was ROI-independent, so only one measurement was obtained. The NPH group had significantly higher PSV, peak mean velocity, and stroke volume values in all readings than both the control and brain atrophy groups. The accuracy of PSV for the diagnosis of NPH was 82.7%, and the accuracy of peak mean velocity was 92.5-93.3% for the three readings. Stroke volume had perfect accuracy of 100% for the three readings. The stroke volume had higher ICCs (0.97 and 0.98) than the peak mean velocity (0.88). The intraobserver repeatability and interobserver repeatability of peak mean velocity were 1.9 cm/s, and the intraobserver repeatability and interobserver repeatability of stroke volume were 27.4 and 19.6 µL/cycle, respectively.
  
  
  CONCLUSIONS
  Stroke volume had better agreement and repeatability and was more accurate than peak mean velocity for the diagnosis of NPH. PSV lacks variability but was the least accurate.
authors.affiliation: 1 Department of Diagnostic and Interventional Radiology, Mansoura University, 12 El-Gomhoreya St, Mansoura 35112, Egypt.
authors.forename: Ahmed Mohamed
authors.initials: AM
authors.lastname: Tawfik
authors.affiliation: 1 Department of Diagnostic and Interventional Radiology, Mansoura University, 12 El-Gomhoreya St, Mansoura 35112, Egypt.
authors.forename: Lamiaa
authors.initials: L
authors.lastname: Elsorogy
authors.affiliation: 1 Department of Diagnostic and Interventional Radiology, Mansoura University, 12 El-Gomhoreya St, Mansoura 35112, Egypt.
authors.forename: Rabab
authors.initials: R
authors.lastname: Abdelghaffar
authors.affiliation: 2 Department of Neurology, Mansoura University, Mansoura, Egypt.
authors.forename: Ayman Abdel
authors.initials: AA
authors.lastname: Naby
authors.affiliation: 2 Department of Neurology, Mansoura University, Mansoura, Egypt.
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Elmenshawi
mesh_terms: D002555:Cerebrospinal Fluid / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000134:cerebrospinal fluid* / Q000000981:diagnostic imaging*; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012212:Rheology / Q000379:methods*; D012680:Sensitivity and Specificity
keywords: CSF flow; aqueductal stroke volume; normal-pressure hydrocephalus (NPH); phase-contrast MRI