title: Repeatability of Standardized and Normalized Relative CBV in Patients with Newly Diagnosed Glioblastoma.
abstract: OBJECTIVE
  For more widespread clinical use advanced imaging methods such as relative cerebral blood volume must be both accurate and repeatable. The aim of this study was to determine the repeatability of relative CBV measurements in newly diagnosed glioblastoma multiforme by using several of the most commonly published estimation techniques.
  
  
  METHODS
  The relative CBV estimates were calculated from dynamic susceptibility contrast MR imaging in double-baseline examinations for 33 patients with treatment-naïve and pathologically proved glioblastoma multiforme (men = 20; mean age = 55 years). Normalized and standardized relative CBV were calculated by using 6 common postprocessing methods. The repeatability of both normalized and standardized relative CBV, in both tumor and contralateral brain, was examined for each method with metrics of repeatability, including the repeatability coefficient and within-subject coefficient of variation. The minimum sample size required to detect a parameter change of 10% or 20% was also determined for both normalized relative CBV and standardized relative CBV for each estimation method.
  
  
  RESULTS
  When ordered by the repeatability coefficient, methods using postprocessing leakage correction and ΔR2*(t) techniques offered superior repeatability. Across processing techniques, the standardized relative CBV repeatability in normal-appearing brain was comparable with that in tumor (P = .31), yet inferior in tumor for normalized relative CBV (P = .03). On the basis of the within-subject coefficient of variation, tumor standardized relative CBV estimates were less variable (13%-20%) than normalized relative CBV estimates (24%-67%). The minimum number of participants needed to detect a change of 10% or 20% is 118-643 or 30-161 for normalized relative CBV and 109-215 or 28-54 for standardized relative CBV.
  
  
  CONCLUSIONS
  The ΔR2* estimation methods that incorporate leakage correction offer the best repeatability for relative CBV, with standardized relative CBV being less variable and requiring fewer participants to detect a change compared with normalized relative CBV.
authors.affiliation: From the Departments of Radiology (M.A.P., K.M.S., E.S.P.).
authors.forename: M A
authors.initials: MA
authors.lastname: Prah
authors.affiliation: Department of Radiology (S.M.S., J.K.-C., E.R.G., T.T.B., B.R.R.), Massachusetts General Hospital, Boston, Massachusetts.
authors.forename: S M
authors.initials: SM
authors.lastname: Stufflebeam
authors.affiliation: From the Departments of Radiology (M.A.P., K.M.S., E.S.P.) Radiation Oncology (E.S.P.), Medical College of Wisconsin, Milwaukee, Wisconsin.
authors.forename: E S
authors.initials: ES
authors.lastname: Paulson
authors.affiliation: Department of Radiology (S.M.S., J.K.-C., E.R.G., T.T.B., B.R.R.), Massachusetts General Hospital, Boston, Massachusetts.
authors.forename: J
authors.initials: J
authors.lastname: Kalpathy-Cramer
authors.affiliation: Department of Radiology (S.M.S., J.K.-C., E.R.G., T.T.B., B.R.R.), Massachusetts General Hospital, Boston, Massachusetts.
authors.forename: E R
authors.initials: ER
authors.lastname: Gerstner
authors.affiliation: Department of Radiology (S.M.S., J.K.-C., E.R.G., T.T.B., B.R.R.), Massachusetts General Hospital, Boston, Massachusetts.
authors.forename: T T
authors.initials: TT
authors.lastname: Batchelor
authors.affiliation: Department of Radiology (D.P.B.), Duke University Medical Center, Durham, North Carolina.
authors.forename: D P
authors.initials: DP
authors.lastname: Barboriak
authors.affiliation: Department of Radiology (S.M.S., J.K.-C., E.R.G., T.T.B., B.R.R.), Massachusetts General Hospital, Boston, Massachusetts.
authors.forename: B R
authors.initials: BR
authors.lastname: Rosen
authors.affiliation: From the Departments of Radiology (M.A.P., K.M.S., E.S.P.) kathleen@mcw.edu.
authors.forename: K M
authors.initials: KM
authors.lastname: Schmainda
mesh_terms: D000328:Adult; D000368:Aged; D001811:Blood Volume Determination / Q000379:methods* / Q000592:standards*; D001932:Brain Neoplasms / Q000503:physiopathology*; D005260:Female; D005909:Glioblastoma / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012015:Reference Standards