Scheef Lukas, Nordmeyer-Massner Jurek A, Smith-Collins Adam Pr, Müller Nicole, Stegmann-Woessner Gaby, Jankowski Jacob, Gieseke Jürgen, Born Mark, Seitz Hermann, Bartmann Peter, Schild Hans H, Pruessmann Klaas P, Heep Axel, Boecker Henning
Department of Radiology, University of Bonn, Bonn, Germany.
Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland.
PLoS One. 2017 Jan 11;12(1):e0169392. doi: 10.1371/journal.pone.0169392. eCollection 2017.
Functional magnetic resonance imaging (fMRI) in neonates has been introduced as a non-invasive method for studying sensorimotor processing in the developing brain. However, previous neonatal studies have delivered conflicting results regarding localization, lateralization, and directionality of blood oxygenation level dependent (BOLD) responses in sensorimotor cortex (SMC). Amongst the confounding factors in interpreting neonatal fMRI studies include the use of standard adult MR-coils providing insufficient signal to noise, and liberal statistical thresholds, compromising clinical interpretation at the single subject level.
PATIENTS / METHODS: Here, we employed a custom-designed neonatal MR-coil adapted and optimized to the head size of a newborn in order to improve robustness, reliability and validity of neonatal sensorimotor fMRI. Thirteen preterm infants with a median gestational age of 26 weeks were scanned at term-corrected age using a prototype 8-channel neonatal head coil at 3T (Achieva, Philips, Best, NL). Sensorimotor stimulation was elicited by passive extension/flexion of the elbow at 1 Hz in a block design. Analysis of temporal signal to noise ratio (tSNR) was performed on the whole brain and the SMC, and was compared to data acquired with an 'adult' 8 channel head coil published previously. Task-evoked activation was determined by single-subject SPM8 analyses, thresholded at p < 0.05, whole-brain FWE-corrected.
Using a custom-designed neonatal MR-coil, we found significant positive BOLD responses in contralateral SMC after unilateral passive sensorimotor stimulation in all neonates (analyses restricted to artifact-free data sets = 8/13). Improved imaging characteristics of the neonatal MR-coil were evidenced by additional phantom and in vivo tSNR measurements: phantom studies revealed a 240% global increase in tSNR; in vivo studies revealed a 73% global and a 55% local (SMC) increase in tSNR, as compared to the 'adult' MR-coil.
Our findings strengthen the importance of using optimized coil settings for neonatal fMRI, yielding robust and reproducible SMC activation at the single subject level. We conclude that functional lateralization of SMC activation, as found in children and adults, is already present in the newborn period.
功能磁共振成像（fMRI）已被引入作为研究发育中大脑感觉运动处理的一种非侵入性方法。然而，先前的新生儿研究在感觉运动皮层（SMC）中血氧水平依赖（BOLD）反应的定位、侧化和方向性方面得出了相互矛盾的结果。解释新生儿fMRI研究的混杂因素包括使用标准成人MR线圈，其提供的信号噪声不足，以及宽松的统计阈值，这损害了单受试者水平的临床解释。
患者/方法：在此，我们采用了一种根据新生儿头部大小定制和优化的新生儿MR线圈，以提高新生儿感觉运动fMRI的稳健性、可靠性和有效性。对13名中位胎龄为26周的早产儿在足月校正年龄时使用3T的原型8通道新生儿头部线圈（Achieva，飞利浦，贝斯特，荷兰）进行扫描。以1Hz的频率通过被动伸展/弯曲肘部以块设计引发感觉运动刺激。对全脑和SMC进行时间信号噪声比（tSNR）分析，并与先前发表的使用“成人”8通道头部线圈获取的数据进行比较。任务诱发激活通过单受试者SPM8分析确定，阈值为p < 0.05，全脑FWE校正。
使用定制设计的新生儿MR线圈，我们发现所有新生儿在单侧被动感觉运动刺激后对侧SMC中存在显著的阳性BOLD反应（分析限于无伪影数据集 = 8/13）。额外的体模和体内tSNR测量证明了新生儿MR线圈改善的成像特性：体模研究显示tSNR整体增加240%；与“成人”MR线圈相比，体内研究显示tSNR整体增加73%，局部（SMC）增加55%。
我们的研究结果强化了为新生儿fMRI使用优化线圈设置的重要性，在单受试者水平上产生稳健且可重复的SMC激活。我们得出结论，儿童和成人中发现的SMC激活功能侧化在新生儿期就已存在。
