Mamach Martin, Wilke Florian, Durisin Martin, Beger Frank A, Finke Mareike, Büchner Andreas, Schultz Barbara, Schultz Arthur, Geworski Lilli, Bengel Frank M, Lenarz Thomas, Lesinski-Schiedat Anke, Berding Georg
Department of Nuclear Medicine, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.
Cluster of Excellence Hearing4all, Hannover Medical School, Hannover, Germany.
EJNMMI Res. 2018 Feb 5;8(1):11. doi: 10.1186/s13550-018-0362-z.
O-Water positron emission tomography (PET) enables functional imaging of the auditory system during stimulation via a promontory electrode or cochlear implant, which is not possible using functional magnetic resonance imaging (fMRI). Although PET has been introduced in this context decades ago, its feasibility when performed during general anesthesia has not yet been explored. However, due to a shift to earlier (and bilateral) auditory implantation, the need to study children during general anesthesia appeared, since they are not able to cooperate during scanning. Therefore, we evaluated retrospectively results of individual SPM (statistical parametric mapping) analysis of O-water PET in 17 children studied during general anesthesia and compared them to those in 9 adults studied while awake. Specifically, the influence of scan duration, smoothing filter kernel employed during preprocessing, and cut-off value used for statistical inferences were evaluated. Frequencies, peak heights, and extents of activations in auditory and extra-auditory brain regions (AR and eAR) were registered.
It was possible to demonstrate activations in auditory brain regions during general anesthesia; however, the frequency and markedness of positive findings were dependent on some of the abovementioned influence factors. Scan duration (60 vs. 90 s) had no significant influence on peak height of auditory cortex activations. To achieve a similar frequency and extent of AR activations during general anesthesia compared to waking state, a lower cut-off for statistical inferences (p < 0.05 or p < 0.01 vs. p < 0.001) had to be applied. However, this lower cut-off was frequently associated with unexpected, "artificial" activations in eAR. These activations in eAR could be slightly reduced by the use of a stronger smoothing filter kernel during preprocessing of the data (e.g., [30 mm]).
Our data indicate that it is feasible to detect auditory cortex activations in O-water PET during general anesthesia. Combined with the improved signal to noise ratios of modern PET scanners, this suggests reasonable prospects for further evaluation of the method for clinical use in auditory implant users. Adapted parameters for data analysis seem to be helpful to improve the proportion of signals in AR versus eAR.
O水正电子发射断层扫描（PET）能够在通过岬电极或人工耳蜗刺激时对听觉系统进行功能成像，而功能磁共振成像（fMRI）则无法做到这一点。尽管PET在这一领域几十年前就已被引入，但其在全身麻醉期间进行的可行性尚未得到探索。然而，由于向更早（且双侧）的听觉植入转变，出现了在全身麻醉期间研究儿童的需求，因为他们在扫描过程中无法配合。因此，我们回顾性评估了17名在全身麻醉期间接受研究的儿童的O水PET的个体统计参数映射（SPM）分析结果，并将其与9名清醒状态下接受研究的成年人的结果进行比较。具体而言，评估了扫描持续时间、预处理期间使用的平滑滤波核以及用于统计推断的截止值的影响。记录了听觉和听觉外脑区（AR和eAR）激活的频率、峰值高度和范围。
在全身麻醉期间能够证明听觉脑区的激活；然而，阳性结果的频率和显著性取决于上述一些影响因素。扫描持续时间（60秒与90秒）对听觉皮层激活的峰值高度没有显著影响。为了在全身麻醉期间与清醒状态下相比获得相似的AR激活频率和范围，必须应用更低的统计推断截止值（p < 0.05或p < 0.01与p < 0.001）。然而，这种较低的截止值经常与eAR中意外的“人工”激活相关。在数据预处理期间使用更强的平滑滤波核（例如，[30毫米]）可以略微减少eAR中的这些激活。
我们的数据表明，在全身麻醉期间通过O水PET检测听觉皮层激活是可行的。结合现代PET扫描仪提高的信噪比，这表明该方法在听觉植入使用者临床应用的进一步评估方面具有合理的前景。适应的数据分析参数似乎有助于提高AR与eAR中信号的比例。
