Kaller Simon, Rullmann Michael, Patt Marianne, Becker Georg-Alexander, Luthardt Julia, Girbardt Johanna, Meyer Philipp M, Werner Peter, Barthel Henryk, Bresch Anke, Fritz Thomas H, Hesse Swen, Sabri Osama
Department of Nuclear Medicine, University of Leipzig, Liebigstrasse 18, D-04103, Leipzig, Germany.
Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
Eur J Nucl Med Mol Imaging. 2017 Jun;44(6):1025-1032. doi: 10.1007/s00259-017-3645-0. Epub 2017 Feb 14.
The role of dopamine D-type receptor (DR)-expressing neurons in the regulation of motivated behavior and reward prediction has not yet been fully established. As a prerequisite for future research assessing D-mediated neuronal network regulation using simultaneous PET/MRI and DR-selective [C]SCH23390, this study investigated the stability of central DR measurements between two independent PET/MRI sessions under baseline conditions.
Thirteen healthy volunteers (7 female, age 33 ± 13 yrs) underwent 90-min emission scans, each after 90-s bolus injection of 486 ± 16 MBq [C]SCH23390, on two separate days within 2-4 weeks using a PET/MRI system. Parametric images of DR distribution volume ratio (DVR) and binding potential (BP) were generated by a multi-linear reference tissue model with two parameters and the cerebellar cortex as receptor-free reference region. Volume-of-interest (VOI) analysis was performed with manual VOIs drawn on consecutive transverse MRI slices for brain regions with high and low DR density.
The DVR varied from 2.5 ± 0.3 to 2.9 ± 0.5 in regions with high DR density (e.g. the head of the caudate) and from 1.2 ± 0.1 to 1.6 ± 0.2 in regions with low DR density (e.g. the prefrontal cortex). The absolute variability of the DVR ranged from 2.4% ± 1.3% to 5.1% ± 5.3%, while Bland-Altman analyses revealed very low differences in mean DVR (e.g. 0.013 ± 0.17 for the nucleus accumbens). Intraclass correlation (one-way, random) indicated very high agreement (0.93 in average) for both DVR and BP values. Accordingly, the absolute variability of BP ranged from 7.0% ± 4.7% to 12.5% ± 10.6%; however, there were regions with very low DR content, such as the occipital cortex, with higher mean variability.
The test-retest reliability of DR measurements in this study was very high. This was the case not only for DR-rich brain areas, but also for regions with low DR density. These results will provide a solid base for future joint PET/MRI data analyses in stimulation-dependent mapping of DR-containing neurons and their effects on projections in neuronal circuits that determine behavior.
表达多巴胺D型受体（DR）的神经元在动机行为调节和奖赏预测中的作用尚未完全明确。作为未来使用同步PET/MRI和DR选择性[C]SCH23390评估D介导的神经网络调节研究的前提条件，本研究调查了在基线条件下两次独立PET/MRI检查之间中枢DR测量的稳定性。
13名健康志愿者（7名女性，年龄33±13岁）在2至4周内的两个不同日期，使用PET/MRI系统，在静脉推注486±16MBq[C]SCH23390 90秒后，分别进行90分钟的发射扫描。通过具有两个参数且以小脑皮质作为无受体参考区域的多线性参考组织模型生成DR分布体积比（DVR）和结合潜能（BP）的参数图像。利用在连续横向MRI切片上手动绘制的感兴趣区（VOI），对DR密度高和低的脑区进行感兴趣区分析。
在DR密度高的区域（如尾状核头部），DVR在2.5±0.3至2.9±0.5之间变化；在DR密度低的区域（如前额叶皮质），DVR在1.2±0.1至1.6±0.2之间变化。DVR的绝对变异性范围为2.4%±1.3%至5.1%±5.3%，而Bland-Altman分析显示平均DVR差异非常小（如伏隔核为0.013±0.17）。组内相关（单向，随机）表明DVR和BP值的一致性非常高（平均为0.93）。因此，BP的绝对变异性范围为7.0%±4.7%至12.5%±10.6%；然而，在DR含量非常低的区域，如枕叶皮质，平均变异性较高。
本研究中DR测量的重测信度非常高。不仅富含DR的脑区如此，DR密度低的区域也是如此。这些结果将为未来在刺激依赖的含DR神经元及其对决定行为的神经回路投射影响的映射研究中联合PET/MRI数据分析提供坚实基础。
