Wende Tim, Kasper Johannes, Wilhelmy Florian, Dietel Eric, Hamerla Gordian, Scherlach Cordula, Meixensberger Jürgen, Fehrenbach Michael Karl
Department of Neurosurgery, University Hospital Leipzig, Liebigstr. 20, 04103 Leipzig, Germany.
Department of Neuroradiology, University Hospital Leipzig, Liebigstr. 20, 04103 Leipzig, Germany.
Brain Sci. 2021 May 16;11(5):650. doi: 10.3390/brainsci11050650.
Tractography has become a standard technique for planning neurosurgical operations in the past decades. This technique relies on diffusion magnetic resonance imaging. The cutoff value for the fractional anisotropy (FA) has an important role in avoiding false-positive and false-negative results. However, there is a wide variation in FA cutoff values.
We analyzed a prospective cohort of 14 patients (six males and eight females, 50.1 ± 4.0 years old) with intracerebral tumors that were mostly gliomas. Magnetic resonance imaging (MRI) was obtained within 7 days before and within 7 days after surgery with T1 and diffusion tensor image (DTI) sequences. We, then, reconstructed the corticospinal tract (CST) in all patients and extracted the FA values within the resulting volume.
The mean FA in all CSTs was 0.4406 ± 0.0003 with the fifth percentile at 0.1454. FA values in right-hemispheric CSTs were lower ( < 0.0001). Postoperatively, the FA values were more condensed around their mean ( < 0.0001). The analysis of infiltrated or compressed CSTs revealed a lower fifth percentile (0.1407 ± 0.0109 versus 0.1763 ± 0.0040, = 0.0036).
An FA cutoff value of 0.15 appears to be reasonable for neurosurgical patients and may shorten the tractography workflow. However, infiltrated fiber bundles must trigger vigilance and may require lower cutoffs.
在过去几十年中，纤维束成像已成为神经外科手术规划的标准技术。该技术依赖于扩散磁共振成像。分数各向异性（FA）的截断值在避免假阳性和假阴性结果方面具有重要作用。然而，FA截断值存在很大差异。
我们分析了一个前瞻性队列，其中包括14例脑内肿瘤患者（6例男性和8例女性，年龄50.1±4.0岁），大多数为胶质瘤。在手术前7天内和手术后7天内，使用T1和扩散张量图像（DTI）序列进行磁共振成像（MRI）检查。然后，我们在所有患者中重建皮质脊髓束（CST），并在所得体积内提取FA值。
所有CST的平均FA为0.4406±0.0003，第五百分位数为0.1454。右半球CST的FA值较低（<0.0001）。术后，FA值更集中在其平均值周围（<0.0001）。对浸润或受压CST的分析显示，第五百分位数较低（0.1407±0.0109对0.1763±0.0040，P = 0.0036）。
对于神经外科患者，FA截断值为0.15似乎是合理的，并且可能缩短纤维束成像工作流程。然而，浸润的纤维束必须引起警惕，可能需要更低的截断值。
