A VBM study demonstrating 'apparent' effects of a single dose of medication on T1-weighted MRIs.
A VBM study demonstrating 'apparent' effects of a single dose of medication on T1-weighted MRIs.
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DOI：
10.1007/s00429-012-0385-6
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发表时间：
2013-01
影响因子：
3.1
通讯作者：
Childress, Anna Rose
中科院分区：
文献类型：
--
作者：
Franklin, Teresa R.;Wang, Ze;Shin, Joshua;Jagannathan, Kanchana;Suh, Jesse J.;Detre, John A.;O'Brien, Charles P.;Childress, Anna Rose
关键词：
基于体素的形态测量学（VBM）研究已将T1加权磁共振成像（MRI）上观察到的纵向药物或行为诱导的变化解释为神经元结构的变化。虽然神经发生或萎缩肯定会发生，但使用T1加权扫描来识别人类体内脑结构的变化具有脆弱性：动脉血和灰质的T1弛豫时间无法清楚区分，因此，明显报告的结构发现可能至少部分与血流或其他生理信号的变化有关。为了检验这一假设，即明显的结构改变可能反映了与潜在的神经元生长/萎缩无关的其他机制引起的变化，我们获得了高分辨率T1加权结构扫描和5分钟灌注fMRI扫描（血流量的测量），在急性药理学操作给药之前和之后，在受试者内设计中，15名受试者未接受药物治疗或在获取T1加权扫描和伪连续动脉自旋标记（pCASL）灌注fMRI扫描前约110分钟接受20 mg剂量的巴氯芬（FDA批准的抗痉挛药）给药。通过SPM 7中的指数李代数（DARTEL）使用神经形态解剖学配准，我们观察到了与血流变化重叠的背侧头侧前扣带回中的VBM“灰质”信号的肉眼可见的，因此是不可信的，Bacterium诱导的减少[在p < 0.04，T= 6.54，范围：1460体素时校正的家族误差（FWE）]。考虑到单次给药后灰质不太可能减少，这些结果表明，无论基线测量和纵向操作之间的时间间隔如何，血流变化都伪装成T1加权扫描上的灰质减少。这些结果强调了开发人体体内神经成像生物标志物的关键和迫切需要，这些生物标志物可以独特地捕获与血流或其他生理信号相关的神经元结构变化。
Voxel-based morphometry (VBM) studies have interpreted longitudinal medication- or behaviorally-induced changes observed on T1-weighted magnetic resonance images (MRIs) as changes in neuronal structure. Although neurogenesis or atrophy certainly occurs, the use of T1-weighted scans to identify change in brain structure in vivo in humans has a vulnerability: the T1 relaxation time for arterial blood and gray matter are not clearly distinguishable and therefore, apparent reported structural findings might be at least partially related to changes in blood flow or other physiological signals. To examine the hypothesis that apparent structural modifications may reflect changes introduced by additional mechanisms irrespective of potential neuronal growth/atrophy, we acquired a high resolution T1-weighted structural scan and a 5-minute perfusion fMRI scan (a measurement of blood flow), prior to and after administration of an acute pharmacological manipulation, In a within subjects design, 15 subjects were either un-medicated or were administered a 20 mg dose of baclofen (an FDA-approved anti-spastic) approximately 110 minutes prior to acquiring a T1-weighted scan and a pseudo continuous arterial spin labeled (pCASL) perfusion fMRI scan. Using diffeomorphic anatomical registration through exponentiated lie algebra (DARTEL) within SPM7 we observed macroscopic, and therefore implausible, baclofen-induced decreases in VBM ‘gray matter’ signal in the dorsal rostral anterior cingulate [Family-wise error (FWE) corrected at p < 0.04, T= 6.54, extent: 1460 voxels] that overlapped with changes in blood flow. Given that gray matter reductions are unlikely following a single dose of medication these findings suggest that changes in blood flow are masquerading as reductions in gray matter on the T1-weighted scan irrespective of the temporal interval between baseline measures and longitudinal manipulations. These results underscore the crucial and immediate need to develop in vivo neuroimaging biomarkers for humans that can uniquely capture changes in neuronal structure dissociable from those related to blood flow or other physiological signals.
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