Ear, Nose and Throat Clinic, Sahlgrenska University Hospital, Gröna Stråket 5, 41345 Gothenburg, Sweden; Institute of Neuroscience and Physiology, Department of Clinical Neuroscience and Rehabilitation, University of Gothenburg, Per Dubbsgatan 14, 41345 Gothenburg, Sweden.
Department of Medical Physics and Medical Engineering, Sahlgrenska University Hospital, 41345 Gothenburg, Sweden.
Epilepsy Res. 2014 Mar;108(3):481-90. doi: 10.1016/j.eplepsyres.2014.01.017. Epub 2014 Feb 2.
Diffusion tensor tractography of the anterior extent of the optic radiation - Meyer's loop - prior to temporal lobe resection (TLR) may reduce the risk for postoperative visual field defect. Currently there is no standardized way to perform tractography.
To visualize Meyer's loop using deterministic (DTG) and probabilistic tractography (PTG) at different probability levels, with the primary aim to explore possible differences between methods, and the secondary aim to explore anatomical accuracy.
Twenty-three diffusion tensor imaging exams (11 controls and 7 TLR-patients, pre- and post-surgical) were analyzed using DTG and PTG thresholded at probability levels 0.2%, 0.5%, 1%, 5% and 10%. The distance from the tip of the temporal lobe to the anterior limit of Meyer's loop (TP-ML) was measured in 46 optic radiations. Differences in TP-ML between the methods were compared. Results of the control group were compared to dissection studies and to a histological atlas.
For controls and patients together, there were statistically significant differences (p<0.01) for TP-ML between all methods thresholded at PTG ≤1% compared to all methods thresholded at PTG ≥5% and DTG. There were no statistically significant differences between PTG 0.2%, 0.5% and 1% or between PTG 5%, 10% and DTG. For the control group, PTG ≤1% showed a closer match to dissection studies and PTG 1% showed the best match to histological tracings of Meyer's loop.
Choice of tractography method affected the visualized location of Meyer's loop significantly in a heterogeneous, clinically relevant study group. For the controls, PTG at probability levels ≤1% was a closer match to dissection studies. To determine the anterior extent of Meyer's loop, PTG is superior to DTG and the probability level of PTG matters.
在进行颞叶切除术（TLR）之前，对视辐射的前部-迈耶环（Meyer's loop）进行弥散张量纤维束成像（tractography），可能会降低术后视野缺损的风险。目前，尚无对其进行成像的标准化方法。
使用确定性（DTG）和概率性纤维束成像（PTG）在不同概率水平上对迈耶环进行可视化，主要目的是探索不同方法之间的差异，次要目的是探索解剖学准确性。
对 23 例弥散张量成像检查（11 例对照和 7 例 TLR 患者，术前和术后）进行分析，使用 DTG 和 PTG 分别在概率水平为 0.2%、0.5%、1%、5%和 10%进行阈值化。在 46 条视辐射中测量从颞叶尖端到迈耶环前界的距离（TP-ML）。比较不同方法之间 TP-ML 的差异。将对照组的结果与解剖研究和组织学图谱进行比较。
对于对照组和患者，在所有阈值为 PTG ≤1%的方法与所有阈值为 PTG ≥5%和 DTG 的方法相比，TP-ML 存在统计学显著差异（p<0.01）。PTG 0.2%、0.5%和 1%之间或 PTG 5%、10%和 DTG 之间无统计学显著差异。对于对照组，PTG ≤1%与解剖研究更匹配，而 PTG 1%与迈耶环的组织学轨迹更匹配。
在一个异质的、具有临床相关性的研究组中，纤维束成像方法的选择显著影响了迈耶环的可视化位置。对于对照组，PTG 在概率水平≤1%与解剖研究更匹配。为了确定迈耶环的前部范围，PTG 优于 DTG，且 PTG 的概率水平很重要。
