He Lili, Wang Jinghua, Lu Zhong-Lin, Kline-Fath Beth M, Parikh Nehal A
Perinatal Institute, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., MLC 7009, Cincinnati, OH, 45229, USA.
Pediatric Neuroimaging Research Consortium, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
Pediatr Radiol. 2018 Aug;48(8):1139-1151. doi: 10.1007/s00247-018-4140-x. Epub 2018 May 2.
Sequence optimization in neonates might improve detection sensitivity of abnormalities for a variety of conditions. However this has been historically challenging because tissue properties such as the longitudinal relaxation time and proton density differ significantly between neonates and adults.
To optimize the magnetization-prepared rapid gradient echo (MP-RAGE) sequence to enhance both signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) efficiencies.
We optimized neonatal MP-RAGE sequence through (1) reducing receive bandwidth to decrease noise, (2) shortening acquisition train length (acquisition number per repetition time or total number of read-out radiofrequency rephrasing pulses) using slice partial Fourier acquisition and (3) simulating the solution of Bloch's equation under optimal receive bandwidth and acquisition train length. Using the optimized sequence parameters, we scanned 12 healthy full-term infants within 2 weeks of birth and four preterm infants at 40 weeks' corrected age.
Compared with a previously published neonatal protocol, we were able to reduce the total scan time by reduce the total scan time by 60% and increase the average SNR efficiency by 160% (P<0.001) and the average CNR efficiency by 26% (P=0.029).
Our in vivo neonatal brain imaging experiments confirmed that both SNR and CNR efficiencies significantly increased with our proposed protocol. Our proposed optimization methodology could be readily extended to other populations (e.g., older children, adults), as well as different organ systems, field strengths and MR sequences.
新生儿序列优化可能会提高多种病症异常的检测灵敏度。然而，由于新生儿和成人之间的组织特性（如纵向弛豫时间和质子密度）存在显著差异，这在历史上一直具有挑战性。
优化磁化准备快速梯度回波（MP-RAGE）序列，以提高信噪比（SNR）和对比噪声比（CNR）效率。
我们通过以下方式优化新生儿MP-RAGE序列：（1）降低接收带宽以减少噪声；（2）使用切片部分傅里叶采集缩短采集序列长度（每个重复时间的采集次数或读出射频重聚脉冲的总数）；（3）在最佳接收带宽和采集序列长度下模拟布洛赫方程的解。使用优化后的序列参数，我们对12名出生后2周内的健康足月儿和4名矫正年龄为40周的早产儿进行了扫描。
与之前发表的新生儿方案相比，我们能够将总扫描时间减少60%，平均SNR效率提高160%（P<0.001），平均CNR效率提高26%（P=0.029）。
我们的新生儿脑成像体内实验证实，我们提出的方案显著提高了SNR和CNR效率。我们提出的优化方法可以很容易地扩展到其他人群（如大龄儿童、成人），以及不同的器官系统、场强和磁共振序列。
