Hilderley A J, Taylor M J, Fehlings D, Chen J L, Wright F V
Bloorview Research Institute, Holland Bloorview Kids Rehabilitation Hospital, 150 Kilgour Rd, Toronto, M4K 1E1, Canada; Rehabilitation Sciences Institute, University of Toronto, 500 University Ave, Toronto, M5G 1V7, Canada.
Diagnostic Imaging, Hospital for Sick Children, 555 University Avenue, Toronto, M5G 1X8, Canada; Department of Medical Imaging, University of Toronto, 263 McCaul Street, Toronto, M5T 1W7, Canada; Department of Psychology, University of Toronto, 100 St. George Street, Toronto, M5S 3G3, Canada.
Int J Dev Neurosci. 2018 May;66:54-62. doi: 10.1016/j.ijdevneu.2018.01.004. Epub 2018 Feb 2.
Measurement of laterality of motor cortical activations may provide valuable information about lower limb control in children with unilateral cerebral palsy (UCP). Evidence from upper limb research suggests that increased contralateral activity may accompany functional gains. However, lower limb areas of activation and associated changes have been underexplored due to challenges with imaging motor cortical leg representations. In this study, methods for a task-based functional magnetic resonance imaging (fMRI) ankle dorsiflexion paradigm were refined with three pilot groups of participants: (i) adults (n = 5); (ii) typically developing (TD) children (n = 5) and; (iii) children with UCP (n = 4). Parameters of experimental design, task resistance, reproducibility, and pre-scan procedures were tested/refined using a staged development approach with additions or changes introduced if image quality did not meet pre-defined standards. When image quality was acceptable for two consecutive participants, the next participant group was recruited to test/refine the next parameter. The final paradigm involved an event-related design of a single dorsiflexion movement against individualized resistance, with two runs per leg. It included a pre-scan session to increase child comfort and determine task resistance. This paradigm produced valid data for laterality index (LI) calculations to determine the ratio of activity in each hemisphere. Ventricle and lesion masks were used in non-linear image registration, and individual thresholds were used for extent-based LI calculations. LI of dominant ankle movements were contralateral (LI ≥ +0.2) for TD children (mean LI = +0.89, std = 0.27) and children with UCP (mean LI = +0.86, std = 0.26). For the affected ankle of children with UCP, LI values indicated ipsilateral and/or contralateral activation (mean LI = +0.02, std = 0.71, range -0.92 to +1.00). This fMRI paradigm will support investigations of cortical activation and mechanisms of skill improvement following lower limb interventions.
测量运动皮层激活的偏侧性可能为单侧脑瘫（UCP）儿童的下肢控制提供有价值的信息。上肢研究的证据表明，对侧活动增加可能伴随着功能改善。然而，由于对运动皮层腿部表征进行成像存在挑战，下肢激活区域及相关变化尚未得到充分研究。在本研究中，通过三组试点参与者对基于任务的功能磁共振成像（fMRI）踝关节背屈范式的方法进行了优化：（i）成年人（n = 5）；（ii）发育正常（TD）儿童（n = 5）；以及（iii）UCP儿童（n = 4）。采用分阶段开发方法测试/优化实验设计参数、任务阻力、可重复性和扫描前程序，如果图像质量未达到预定义标准，则进行补充或更改。当连续两名参与者的图像质量可接受时，招募下一组参与者来测试/优化下一个参数。最终范式涉及针对个体化阻力进行单次背屈运动的事件相关设计，每条腿进行两次扫描。它包括一次扫描前环节，以提高儿童的舒适度并确定任务阻力。该范式产生了用于计算偏侧性指数（LI）以确定每个半球活动比率的有效数据。在非线性图像配准中使用了脑室和病变掩码，并且基于范围的LI计算使用了个体阈值。TD儿童（平均LI = +0.89，标准差 = 0.27）和UCP儿童（平均LI = +0.86，标准差 = 0.26）优势踝关节运动的LI为对侧（LI≥+0.2）。对于UCP儿童的患侧踝关节，LI值表明同侧和/或对侧激活（平均LI = +0.02，标准差 = 0.71，范围 -0.92至 +1.00）。这种fMRI范式将支持对下肢干预后皮层激活和技能改善机制的研究。
