García Santos José María, Ordóñez Cristina, Torres del Río Silvia
Area de Neurorradiología, Cabeza y Cuello, Servicio de Radiodiagnóstico, Hospital General Universitario Morales Meseguer, Murcia, Spain.
Magn Reson Imaging. 2008 Jan;26(1):35-44. doi: 10.1016/j.mri.2007.04.004. Epub 2007 Jun 4.
To demonstrate drop in brain ADC measurements from low to high b values; to evaluate the structural information provided based on those changes; and to discuss the anatomical reasons for ADC differences.
Four cerebral ROI (precuneus-PRC, hippocampus-HIP, and the genu-GCC and splenium-SCC of the corpus callosum-CC) were drawn for ADC measurements with low (1000) and high (3000) b-value DWI in 50 normal subjects. ANOVA and Bonferroni correction tested ADC differences between areas, between both hemispheres, between GCC and SCC, and between b-value related ADC drop within areas. Pearson test evaluated dependence of interhemispheric and intercallosum ADC measurements obtained with the same b-value, dependence between areas of intrazonal drop, and the interhemispheric and intercallosum dependence of intrazonal drop.
ADCs differed between areas (P<.0001). Interhemispheric ADC only differed in PRC with low b-value (P<.027). No HIP asymmetries occurred regardless the b-value. ADC drop within PRC and HIP was similar but differed (P<.0001) from ADC drop within both CC ROI. ADC drop was also different between GCC and SCC (P<.0001). In PRC and HIP, ADC showed a significant interhemispheric and intrazonal dependence (P<.0001). There was no GCC to SCC ADC dependence. Intrazonal dependence in the CC was only significant in the SCC (P<.001). Interhemispheric dependence of intrazonal drop was significant (PRC P=.007; HIP P<.0001) but failed to reach significance in the CC.
Low and high b-value measurements show different diffusion behaviours within different tissues, especially in a highly anisotropic structure as the corpus callosum. This fact can provide valuable information about brain structure and different diffusion compartments in clinical DWI.
证明脑ADC测量值从低b值到高b值的下降；评估基于这些变化所提供的结构信息；并讨论ADC差异的解剖学原因。
在50名正常受试者中，绘制四个脑区感兴趣区（楔前叶-PRC、海马-HIP以及胼胝体的膝部-GCC和压部-SCC），用于在低（1000）和高（3000）b值的扩散加权成像（DWI）上进行ADC测量。方差分析和Bonferroni校正检验了不同区域之间、两个半球之间、GCC和SCC之间以及区域内与b值相关的ADC下降之间的ADC差异。Pearson检验评估了在相同b值下获得的半球间和胼胝体间ADC测量值的相关性、区域内下降区域之间的相关性以及区域内下降的半球间和胼胝体间相关性。
不同区域的ADC值存在差异（P<0.0001）。仅在低b值时，PRC的半球间ADC存在差异（P<0.027）。无论b值如何，HIP均未出现不对称性。PRC和HIP内的ADC下降相似，但与两个胼胝体感兴趣区内的ADC下降不同（P<0.0001）。GCC和SCC之间的ADC下降也不同（P<0.0001）。在PRC和HIP中，ADC显示出显著的半球间和区域内相关性（P<0.0001）。GCC与SCC的ADC之间不存在相关性。胼胝体内的区域内相关性仅在SCC中显著（P<0.001）。区域内下降的半球间相关性显著（PRC中P=0.007；HIP中P<0.0001），但在胼胝体中未达到显著水平。
低b值和高b值测量在不同组织中显示出不同的扩散行为，尤其是在像胼胝体这样高度各向异性的结构中。这一事实可为临床扩散加权成像中有关脑结构和不同扩散腔室提供有价值的信息。
