Harris Ashley D, Govindaraj Mirthula, Frayne Richard
Seaman Family MR Research Centre, Foothills Medical Centre, Calgary Health Region, Calgary, Alberta, Canada.
J Magn Reson Imaging. 2008 Mar;27(3):629-33. doi: 10.1002/jmri.21166.
To determine the minimum detectable difference (MDD) and investigate variability of region-of-interest (ROI) analysis of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) in acute ischemic stroke.
Ten patients with acute stroke (<24 hours) and moderate-to-large infarcts were imaged using a fast diffusion tensor technique. Four observers repeated three trials, during which each of two ROI types (free-hand polygon and ellipse) were drawn in white and gray matter (WM and GM) on FA and ADC maps. Analysis-of-variance techniques examined tissue and ROI type effects as well as inter- and intraobserver variability. F-tests examined the variability differences between ROI types.
The MDD for ADC was 0.160 x 10(-3) mm(2) s(-1) in WM and 0.212 x 10(-3) mm(2) s(-1) in GM. The FA MDD was 0.19 in WM and 0.10 in GM. Tissue but not ROI type affected the mean values for both ADC and FA maps. Intraobserver reliability was substantial, while interobserver reliability was poor-to-moderate. No variability differences were found by ROI types.
The MDD for WM and GM in normal and ischemic tissue were calculated. Inter- and intraobserver variability and tissue type affect ROI analysis of ADC and FA maps.
确定最小可检测差异（MDD），并研究急性缺血性卒中表观扩散系数（ADC）和分数各向异性（FA）感兴趣区（ROI）分析的变异性。
对10例急性卒中（<24小时）且梗死灶为中到大的患者采用快速扩散张量技术进行成像。4名观察者重复3次试验，在此期间在FA和ADC图上的白质和灰质（WM和GM）中绘制两种ROI类型（徒手多边形和椭圆形）中的每一种。方差分析技术检查了组织和ROI类型的影响以及观察者间和观察者内的变异性。F检验检查了ROI类型之间的变异性差异。
ADC在WM中的MDD为0.160×10⁻³mm²/s，在GM中为0.212×10⁻³mm²/s。FA在WM中的MDD为0.19，在GM中为0.10。组织而非ROI类型影响ADC和FA图的平均值。观察者内可靠性较高，而观察者间可靠性为差到中等。未发现ROI类型之间的变异性差异。
计算了正常和缺血组织中WM和GM的MDD。观察者间和观察者内变异性以及组织类型影响ADC和FA图的ROI分析。
