Brain, TRI and Department of Neurosurgery, University Hospital Antwerp, Antwerp, Belgium.
J Nucl Med. 2012 Oct;53(10):1550-7. doi: 10.2967/jnumed.112.102939. Epub 2012 Aug 23.
In tinnitus, PET and other functional imaging modalities have shown functional changes not only in the auditory cortex but also in nonauditory regions such as the limbic, frontal, and parietal areas. Nonetheless, disparities in task dimension among studies, low statistical power due to small sample size, and the intrinsic uncertainty of a modality that measures activity indirectly limit the comprehensive understanding of the results from PET studies. These difficulties prompted us to undertake a metaanalysis of PET studies on tinnitus using a coordinate-based technique (activation-likelihood estimation) to retrieve the most consistent activation areas across different task dimensions and to compare the results with those from other imaging modalities.
We performed 2 activation-likelihood estimation metaanalyses on data from 10 studies with 56 foci in which we examined the contrast between tinnitus individuals and controls and the difference in activation between sound stimuli and resting state in tinnitus individuals.
The studies show that the most consistently activated regions in tinnitus subjects, compared with controls, were the left primary and bilateral secondary auditory cortices, left middle and bilateral inferior temporal gyri, left parahippocampal area, left geniculum body, left precuneus, right anterior cingulate cortex, right claustrum, right middle and inferior frontal gyri, and right angular gyrus. The relatively activated area under sound stimuli, compared with resting state, in tinnitus subjects was the secondary auditory cortex. Our study reconfirms the findings of previous quantitative electroencephalography or magnetoencephalography studies because most of the 14 brain areas with significant activation found in our metaanalysis replicate these earlier data. Our results suggest that the areas described in the tinnitus network are solidly replicable regardless of the applied functional imaging technique.
This study proves that PET is a useful modality for tinnitus research and solidifies human tinnitus research itself by confirming previously described brain areas involved in the generation and maintenance of tinnitus.
在耳鸣中，PET 和其他功能成像方式不仅在听觉皮层中显示出功能变化，而且在边缘、额叶和顶叶等非听觉区域中也显示出功能变化。尽管如此，由于样本量小，研究中的任务维度差异、统计能力低以及间接测量活动的模态固有不确定性限制了对 PET 研究结果的全面理解。这些困难促使我们使用基于坐标的技术（激活似然估计）对耳鸣的 PET 研究进行荟萃分析，以检索不同任务维度下最一致的激活区域，并将结果与其他成像方式进行比较。
我们对 10 项研究的数据进行了 2 次激活似然估计荟萃分析，其中包括 56 个焦点，我们检查了耳鸣个体与对照组之间的对比，以及耳鸣个体在声音刺激和静息状态之间的激活差异。
与对照组相比，这些研究表明耳鸣患者最一致激活的区域是左侧初级和双侧次级听觉皮层、左侧中颞叶和双侧下颞叶、左侧海马旁回、左侧膝状体体、左侧楔前叶、右侧前扣带皮层、右侧屏状核、右侧中颞叶和下额回以及右侧角回。与静息状态相比，耳鸣患者在声音刺激下相对激活的区域是次级听觉皮层。我们的研究再次证实了以前的定量脑电图或脑磁图研究的发现，因为我们荟萃分析中发现的 14 个具有显著激活的大脑区域中的大多数都复制了这些早期数据。我们的结果表明，无论应用何种功能成像技术，描述的耳鸣网络区域都具有很强的可重复性。
这项研究证明 PET 是耳鸣研究的有用方式，并通过确认先前描述的涉及耳鸣产生和维持的大脑区域，巩固了人类耳鸣研究本身。
