Department of Diagnostic Imaging, Ottawa General Hospital, Ottawa, Ontario, Canada.
Magn Reson Med. 2011 Aug;66(2):498-504. doi: 10.1002/mrm.22856. Epub 2011 Feb 28.
Dynamic contrast-enhanced (DCE) MRI is often used to measure the transfer constant (Ktrans) and distribution volume (ve) in pelvic tumors. For optimal accuracy and reproducibility, one must quantify the arterial input function (AIF). Unfortunately, this is challenging due to inflow and signal saturation. A potential solution is to use MR signal phase (ϕ), which is relatively unaffected by these factors. We hypothesized that phase-derived AIFs (AIFϕ) would provide more reproducible Ktrans and ve values than magnitude-derived AIFs (AIF|S|). We tested this in 27 prostate dynamic contrast-enhanced MRI studies (echo time=2.56 ms, temporal resolution=13.5 s), using muscle as a standard. AIFϕ peak amplitude varied much less as a function of measurement location (inferior-superior) than AIF|S| (5.6±0.6 mM vs. 2.6±1.5 mM), likely as a result of ϕ inflow insensitivity. However, our main hypothesis was not confirmed. The best AIF|S| provided similar reproducibility versus AIFϕ (interpatient muscle Ktrans=0.039±0.021 min(-1) vs. 0.037±0.025 min(-1), ve=0.090±0.041 vs. 0.062±0.022, respectively).
动态对比增强（DCE）MRI 常用于测量盆腔肿瘤的转移常数（Ktrans）和分布容积（ve）。为了获得最佳的准确性和可重复性，必须量化动脉输入函数（AIF）。然而，由于流入和信号饱和，这具有一定挑战性。一种潜在的解决方案是使用相对不受这些因素影响的磁共振信号相位（ϕ）。我们假设相位衍生的 AIF（AIFϕ）将比幅度衍生的 AIF（AIF|S|）提供更具可重复性的 Ktrans 和 ve 值。我们在 27 项前列腺动态对比增强 MRI 研究（回波时间=2.56 ms，时间分辨率=13.5 s）中使用肌肉作为标准对此进行了测试。AIFϕ 峰值幅度随测量位置（下至上）的变化明显小于 AIF|S|（5.6±0.6 mM 与 2.6±1.5 mM），这可能是由于 ϕ 流入不敏感所致。然而，我们的主要假设并未得到证实。最佳的 AIF|S|与 AIFϕ 具有相似的可重复性（患者间肌肉 Ktrans=0.039±0.021 min(-1) 与 0.037±0.025 min(-1)，ve=0.090±0.041 与 0.062±0.022）。
