Department of Neuroradiology, Charité, Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany.
Brain Struct Funct. 2013 Jan;218(1):151-6. doi: 10.1007/s00429-012-0389-2. Epub 2012 Feb 12.
Diffusion Tensor Imaging studies have repeatedly shown a decrease of the fractional anisotropy (FA) parameter in patients with schizophrenia. This has been interpreted as a disturbed microstructural integrity of white matter. However, FA is a relative parameter that is derived from eigenvalues of the diffusion tensor and FA reductions may be the result of decreases in parallel diffusivity (PD) or increases in radial diffusivity (RD). Despite the well-established FA reduction in schizophrenia, little is known what this reduction is based on.
Seventeen patients with schizophrenia were scanned with a DTI protocol and compared to a group of healthy control subjects. In addition to an FA comparison, a detailed analysis of PD and RD values was performed with two approaches to localize changes in diffusion values, i.e. a voxel-based analysis and an anatomically based tract specific analysis.
We found significantly decreased FA values in the patient group when compared to healthy controls. FA decreases were based on an increase in RD, while we observed no significant changes of PD. These changes were predominantly localized in frontal and temporal areas.
RD increases as the underlying change in FA decreases is suggestive of desintegration of myelin, which is in line with histopathological studies suggesting a disturbed myelination in schizophrenia.
弥散张量成像研究反复表明精神分裂症患者的各向异性分数（FA）参数降低。这被解释为白质微观结构完整性受损。然而，FA 是一个相对参数，它是从扩散张量的特征值中得出的，FA 的降低可能是平行扩散系数（PD）降低或径向扩散系数（RD）增加的结果。尽管精神分裂症中存在明确的 FA 降低，但对于这种降低的基础知之甚少。
对 17 名精神分裂症患者进行了 DTI 方案扫描，并与一组健康对照组进行了比较。除了 FA 比较外，还使用两种方法对 PD 和 RD 值进行了详细分析，即体素基分析和基于解剖的束特异性分析，以定位扩散值的变化。
与健康对照组相比，患者组的 FA 值明显降低。FA 的降低是基于 RD 的增加，而 PD 没有观察到显著变化。这些变化主要局限于额区和颞区。
RD 的增加表明 FA 降低的潜在变化提示髓鞘解体，这与提示精神分裂症髓鞘紊乱的组织病理学研究一致。
