James J. Peters VA Medical Center, Mental Health Patient Care Center and Mental Illness, Research Education Clinical Center, Bronx, NY, USA; Icahn School of Medicine at Mount Sinai, Department of Psychiatry, New York, NY, USA.
GE Global Research, Niskayuna, NY, USA.
Prog Neuropsychopharmacol Biol Psychiatry. 2018 Feb 2;81:114-121. doi: 10.1016/j.pnpbp.2017.10.019. Epub 2017 Oct 28.
Standard diffusion tensor imaging measures (e.g., fractional anisotropy; FA) are difficult to interpret in brain regions with crossing white-matter (WM) fibers. Diffusion spectrum imaging (DSI) can be used to resolve fiber crossing, but has been difficult to implement in studies of patients with psychosis given long scan times.
We used four fold accelerated compressed sensing to accelerate DSI acquisition to investigate the superior longitudinal fasciculus (SLF) in 27 (20M/7F) patients with recent onset psychosis and 23 (11M/12F) healthy volunteers. Dependent measures included the number of crossing fiber directions, multi directional anisotropy (MDA), which is a measure sensitive to the anisotropy of the underlying water diffusion in regions of crossing fibers, generalized FA (GFA) computed from the orientation distribution function, FA and tract volume.
Patients demonstrated a greater number of crossing WM fibers, lower MDA, GFA and FA in the left SLF compared to healthy volunteers. Patients also demonstrated a reversal in the normal (R>L) asymmetry of crossing fiber directions in the SLF and a lack of normal (L>R) asymmetry in MDA, GFA and FA compared to healthy volunteers. Lower GFA correlated significantly (p<0.05) with worse overall neuropsychological functioning; posthoc tests revealed significant effects with verbal functioning and processing speed.
Our findings provide the first in vivo evidence for abnormal crossing fibers within the SLF among individuals with psychosis and their functional correlates. A reversal in the normal pattern of WM asymmetry of crossing fibers in patients may be consistent with an aberrant neurodevelopmental process.
标准的弥散张量成像测量（例如，各向异性分数；FA）在存在交叉白质（WM）纤维的脑区较难解释。弥散频谱成像（DSI）可用于解析纤维交叉，但由于扫描时间长，在精神病患者的研究中较难实施。
我们使用四折加速压缩感知来加速 DSI 采集，以研究 27 名（20 名男性/7 名女性）近期发病的精神病患者和 23 名（11 名男性/12 名女性）健康志愿者的上纵束（SLF）。依赖指标包括交叉纤维方向的数量、多向各向异性（MDA），这是一种对交叉纤维区域下水扩散各向异性敏感的指标，从方向分布函数计算的广义各向异性（GFA）、FA 和束流体积。
与健康志愿者相比，患者在左侧 SLF 中表现出更多的交叉 WM 纤维、更低的 MDA、GFA 和 FA。与健康志愿者相比，患者还表现出 SLF 中交叉纤维方向的正常（R>L）不对称性逆转，以及 MDA、GFA 和 FA 中正常（L>R）不对称性缺失。较低的 GFA 与整体神经心理学功能显著相关（p<0.05）；事后检验显示与言语功能和处理速度有显著影响。
我们的研究结果首次提供了精神病患者 SLF 中存在异常交叉纤维及其功能相关性的体内证据。患者中 WM 交叉纤维的正常不对称模式的逆转可能与异常的神经发育过程一致。
