Measurement of the blood T 1 time using conventional myocardial T 1 mapping methods has gained clinical significance in the context of extracellular volume (ECV) mapping and synthetic hematocrit (Hct). However, its accuracy is potentially compromised by in-flow of non-inverted/non-saturated spins and in-flow of spins which are not partially saturated from previous imaging pulses. Bloch simulations were used to analyze various flow effects separately. T 1 measurements of gadolinium doped water were performed using a flow phantom with adjustable flow velocities at 3 T. Additionally, in vivo blood T 1 measurements were performed in 6 healthy subjects (26 ± 5 years, 2 female). To study the T 1 time as a function of the instantaneous flow velocity, T 1 times were evaluated in an axial imaging slice of the descending aorta. Velocity encoded cine measurements were performed to quantify the flow velocity throughout the cardiac cycle. Simulation results show more than 30% loss in accuracy for 10% non-prepared in-flowing spins. However, in- and out-flow to the imaging plane only demonstrated minor impact on the T 1 time. Phantom T 1 times were decreased by up to 200 ms in the flow phantom, due to in-flow of non-prepared spins. High flow velocities cause in-flow of spins that lack partial saturation from the imaging pulses but only lead to negligible T 1 time deviation (less than 30 ms). In vivo measurements confirm a substantial variation of the T 1 time depending on the flow velocity. The highest aortic T 1 times are observed at the time point of minimal flow with increased flow velocity leading to reduction of the measured T 1 time by up to [Formula: see text] at peak velocity. In this work we attempt to dissect the effects of flow on T 1 times, by using simulations, well-controlled, simplified phantom setup and the linear flow pattern in the descending aorta in vivo.

中文翻译：

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为了测量在流动体模和体内评估的血液T 1的影响。

在细胞外体积（ECV）作图和合成血细胞比容（Hct）的背景下，使用常规心肌T 1作图方法测量血液T 1时间已获得临床意义。但是，其准确性可能会受到非反相/非饱和自旋的流入和自先前成像脉冲未部分饱和的自旋的流入的影响。Bloch模拟被用来分别分析各种流动效应。使用流动速度可调的流动体模在3 T下进行T掺杂水的T 1测量。此外，在6位健康受试者（26±5岁，2位女性）中进行了体内血液T 1测量。为了研究T 1时间与瞬时流速的关系，在降主动脉的轴向成像切片中评估了T 1时间。进行速度编码的电影测量以量化整个心动周期的流速。仿真结果显示，对于10％未准备的流入自旋，精度损失超过30％。但是，流入和流出成像平面仅对T 1时间表现出较小的影响。由于未准备好的自旋的流入，幻影T 1的时间在流动体模中最多减少了200 ms。较高的流速会导致自旋流入，该自旋流入缺乏成像脉冲的部分饱和度，但只会导致可忽略的T 1时间偏差（小于30 ms）。体内测量结果证实了T 1时间的实质性变化取决于流速。在最小流量的时间点观察到最高的主动脉T 1次，流速增加，导致测得的T 1时间减少多达[公式：参见文字]以峰值速度。在这项工作中，我们尝试通过使用模拟，良好控制的简化体模设置以及体内降主动脉中的线性流动模式来分析流量对T 1的影响。