De Vis J B, Hendrikse J, Groenendaal F, de Vries L S, Kersbergen K J, Benders M J N L, Petersen E T
Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.
Department of Neonatology, University Medical Center Utrecht, Utrecht, The Netherlands.
Neuroimage Clin. 2014 Mar 19;4:517-25. doi: 10.1016/j.nicl.2014.03.006. eCollection 2014.
The longitudinal relaxation time of blood (T 1b) is influenced by haematocrit (Hct) which is known to vary in neonates. The purpose of this study was threefold: to obtain T 1b values in neonates, to investigate how the T 1b influences quantitative arterial spin labelling (ASL), and to evaluate if known relationships between T 1b and haematocrit (Hct) hold true when Hct is measured by means of a point-of-care device.
One hundred and four neonates with 120 MR scan sessions (3 T) were included. The T 1b was obtained from a T 1 inversion recovery sequence. T 1b-induced changes in ASL cerebral blood flow estimates were evaluated. The Hct was obtained by means of a point-of-care device. Linear regression analysis was used to investigate the relation between Hct and MRI-derived R1 of blood (the inverse of the T 1b).
Mean T 1b was 1.85 s (sd 0.2 s). The mean T 1b in preterm neonates was 1.77 s, 1.89 s in preterm neonates scanned at term-equivalent age (TEA) and 1.81 s in diseased neonates. The T 1b in the TEA was significantly different from the T 1b in the preterm (p < 0.05). The change in perfusion induced by the T 1b was -11% (sd 9.1%, p < 0.001). The relation between arterial-drawn Hct and R1b was R1b = 0.80 × Hct + 0.22, which falls within the confidence interval of the previously established relationships, whereas capillary-drawn Hct did not correlate with R1b.
We demonstrated a wide variability of the T 1b in neonates and the implications it could have in methods relying on the actual T 1b as for instance ASL. It was concluded that arterial-drawn Hct values obtained from a point-of-care device can be used to infer the T 1b whereas our data did not support the use of capillary-drawn Hct for T 1b correction.
血液的纵向弛豫时间(T1b)受血细胞比容(Hct)影响,已知新生儿的血细胞比容会有所变化。本研究有三个目的:获取新生儿的T1b值,研究T1b如何影响定量动脉自旋标记(ASL),以及评估当通过即时检测设备测量血细胞比容时,T1b与血细胞比容(Hct)之间的已知关系是否成立。
纳入104例接受120次磁共振扫描(3T)的新生儿。T1b通过T1反转恢复序列获得。评估T1b引起的ASL脑血流量估计值的变化。血细胞比容通过即时检测设备获得。采用线性回归分析研究血细胞比容与磁共振成像得出的血液R1(T1b的倒数)之间的关系。
平均T1b为1.85秒(标准差0.2秒)。早产儿的平均T1b为1.77秒,足月等效年龄(TEA)扫描的早产儿为1.89秒,患病新生儿为1.81秒。TEA时的T1b与早产儿的T1b有显著差异(p < 0.05)。T1b引起的灌注变化为-11%(标准差9.1%,p < 0.001)。动脉抽取的血细胞比容与R1b的关系为R1b = 0.80×Hct + 0.22,该结果在先前建立的关系的置信区间内,而毛细血管抽取的血细胞比容与R1b无相关性。
我们证明了新生儿T1b的广泛变异性及其对依赖实际T1b的方法(如ASL)可能产生的影响。得出的结论是,从即时检测设备获得的动脉抽取的血细胞比容值可用于推断T1b,而我们的数据不支持使用毛细血管抽取的血细胞比容进行T1b校正。