Repeatability of Standardized and Normalized Relative CBV in XXXX with Newly Diagnosed @entity463 .

@entity1 @entity463 @entity5
BACKGROUND AND PURPOSE: 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 @entity463 multiforme by using several of the most commonly published estimation techniques. MATERIALS AND METHODS: The relative CBV estimates were calculated from dynamic susceptibility contrast MR imaging in double-baseline examinations for 33 @entity1 with treatment-na  ve and pathologically proved @entity463 multiforme ( @entity1 = 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 @entity5 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   R2*(t) techniques offered superior repeatability. Across processing techniques, the standardized relative CBV repeatability in normal-appearing brain was comparable with that in @entity5 (P = .31), yet inferior in @entity5 for normalized relative CBV (P = .03). On the basis of the within-subject coefficient of variation, @entity5 standardized relative CBV estimates were less variable (13%-20%) than normalized relative CBV estimates (24%-67%). The minimum number of @entity1 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   R2* estimation methods that incorporate leakage correction offer the best repeatability for relative CBV, with standardized relative CBV being less variable and requiring fewer @entity1 to detect a change compared with normalized relative CBV.
