Weiss Carolin, Tursunova Irada, Neuschmelting Volker, Lockau Hannah, Nettekoven Charlotte, Oros-Peusquens Ana-Maria, Stoffels Gabriele, Rehme Anne K, Faymonville Andrea Maria, Shah N Jon, Langen Karl Josef, Goldbrunner Roland, Grefkes Christian
Department of Neurosurgery, University of Cologne, Cologne 50924, Germany.
Department of Neurosurgery, University of Cologne, Cologne 50924, Germany ; Department of Neurosurgery, University of Cologne, Cologne 50924, Germany.
Neuroimage Clin. 2015 Jan 20;7:424-37. doi: 10.1016/j.nicl.2015.01.006. eCollection 2015.
Imaging of the course of the corticospinal tract (CST) by diffusion tensor imaging (DTI) is useful for function-preserving tumour surgery. The integration of functional localizer data into tracking algorithms offers to establish a direct structure-function relationship in DTI data. However, alterations of MRI signals in and adjacent to brain tumours often lead to spurious tracking results. We here compared the impact of subcortical seed regions placed at different positions and the influences of the somatotopic location of the cortical seed and clinical co-factors on fibre tracking plausibility in brain tumour patients. The CST of 32 patients with intracranial tumours was investigated by means of deterministic DTI and neuronavigated transcranial magnetic stimulation (nTMS). The cortical seeds were defined by the nTMS hot spots of the primary motor area (M1) of the hand, the foot and the tongue representation. The CST originating from the contralesional M1 hand area was mapped as intra-individual reference. As subcortical region of interests (ROI), we used the posterior limb of the internal capsule (PLIC) and/or the anterior inferior pontine region (aiP). The plausibility of the fibre trajectories was assessed by a-priori defined anatomical criteria. The following potential co-factors were analysed: Karnofsky Performance Scale (KPS), resting motor threshold (RMT), T1-CE tumour volume, T2 oedema volume, presence of oedema within the PLIC, the fractional anisotropy threshold (FAT) to elicit a minimum amount of fibres and the minimal fibre length. The results showed a higher proportion of plausible fibre tracts for the aiP-ROI compared to the PLIC-ROI. Low FAT values and the presence of peritumoural oedema within the PLIC led to less plausible fibre tracking results. Most plausible results were obtained when the FAT ranged above a cut-off of 0.105. In addition, there was a strong effect of somatotopic location of the seed ROI; best plausibility was obtained for the contralateral hand CST (100%), followed by the ipsilesional hand CST (>95%), the ipsilesional foot (>85%) and tongue (>75%) CST. In summary, we found that the aiP-ROI yielded better tracking results compared to the IC-ROI when using deterministic CST tractography in brain tumour patients, especially when the M1 hand area was tracked. In case of FAT values lower than 0.10, the result of the respective CST tractography should be interpreted with caution with respect to spurious tracking results. Moreover, the presence of oedema within the internal capsule should be considered a negative predictor for plausible CST tracking.
通过扩散张量成像（DTI）对皮质脊髓束（CST）走行进行成像，对保留功能的肿瘤手术很有用。将功能定位器数据整合到追踪算法中有助于在DTI数据中建立直接的结构-功能关系。然而，脑肿瘤内部及其邻近区域的MRI信号改变常常导致错误的追踪结果。我们在此比较了置于不同位置的皮质下种子区域的影响，以及皮质种子的躯体定位和临床辅助因素对脑肿瘤患者纤维追踪合理性的影响。通过确定性DTI和神经导航经颅磁刺激（nTMS）对32例颅内肿瘤患者的CST进行了研究。皮质种子由手部、足部和舌部代表区的初级运动区（M1）的nTMS热点定义。将起源于对侧M1手部区域的CST映射为个体内对照。作为皮质下感兴趣区域（ROI），我们使用了内囊后肢（PLIC）和/或脑桥前下区域（aiP）。通过先验定义的解剖学标准评估纤维轨迹的合理性。分析了以下潜在的辅助因素：卡氏功能状态评分（KPS）、静息运动阈值（RMT）、T1增强扫描肿瘤体积、T2水肿体积、PLIC内是否存在水肿、引出最少纤维数量所需的各向异性分数阈值（FAT）以及最小纤维长度。结果显示，与PLIC-ROI相比，aiP-ROI的合理纤维束比例更高。低FAT值以及PLIC内存在瘤周水肿导致纤维追踪结果的合理性降低。当FAT高于0.105这个临界值时，可获得最合理的结果。此外，种子ROI的躯体定位有强烈影响；对侧手部CST获得了最佳合理性（100%），其次是同侧手部CST（>95%）、同侧足部（>85%）和舌部（>75%）CST。总之，我们发现，在脑肿瘤患者中使用确定性CST纤维束成像时，与IC-ROI相比，aiP-ROI产生了更好的追踪结果，尤其是在追踪M1手部区域时。如果FAT值低于0.10，则应谨慎解释相应CST纤维束成像的结果，因为可能存在错误追踪结果。此外，内囊内存在水肿应被视为CST合理追踪的负面预测因素。
