Centre d'Imagerie Moléculaire de Sherbrooke, Département de Médecine Nucléaire et Radiobiologie, Université de Sherbrooke, 3001 12e Avenue Nord, Sherbrooke, Quebec, Canada.
Magn Reson Med. 2013 Mar 1;69(3):781-92. doi: 10.1002/mrm.24318. Epub 2012 May 8.
Reaching the full potential of magnetic resonance imaging (MRI)-positron emission tomography (PET) dual modality systems requires new methodologies in quantitative image analyses. In this study, methods are proposed to convert an arterial input function (AIF) derived from gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA) in MRI, into a (18)F-fluorodeoxyglucose ((18)F-FDG) AIF in PET, and vice versa. The AIFs from both modalities were obtained from manual blood sampling in a F98-Fisher glioblastoma rat model. They were well fitted by a convolution of a rectangular function with a biexponential clearance function. The parameters of the biexponential AIF model were found statistically different between MRI and PET. Pharmacokinetic MRI parameters such as the volume transfer constant (K(trans)), the extravascular-extracellular volume fraction (ν(e)), and the blood volume fraction (ν(p)) calculated with the Gd-DTPA AIF and the Gd-DTPA AIF converted from (18)F-FDG AIF normalized with or without blood sample were not statistically different. Similarly, the tumor metabolic rates of glucose (TMRGlc) calculated with (18) F-FDG AIF and with (18) F-FDG AIF obtained from Gd-DTPA AIF were also found not statistically different. In conclusion, only one accurate AIF would be needed for dual MRI-PET pharmacokinetic modeling in small animal models.
要充分发挥磁共振成像（MRI）-正电子发射断层扫描（PET）双模系统的潜力，需要在定量图像分析中采用新的方法。本研究提出了一种方法，可将 MRI 中的钆二乙烯三胺五乙酸（Gd-DTPA）动脉输入函数（AIF）转换为 PET 中的（18）F-氟代脱氧葡萄糖（（18）F-FDG）AIF，反之亦然。两种模式的 AIF 均通过在 F98-Fisher 胶质母细胞瘤大鼠模型中进行手动采血获得。它们都可以通过矩形函数与双指数清除函数的卷积很好地拟合。发现 MRI 和 PET 之间双指数 AIF 模型的参数在统计学上存在差异。用 Gd-DTPA AIF 计算的 MRI 药代动力学参数，如体积转移常数（K(trans)）、血管外-细胞外体积分数（ν(e)）和血容量分数（ν(p)），以及用 Gd-DTPA AIF 转换的 Gd-DTPA AIF，无论是归一化还是不依赖于血样，均无统计学差异。同样，用（18）F-FDG AIF 计算的肿瘤葡萄糖代谢率（TMRGlc）与用 Gd-DTPA AIF 获得的（18）F-FDG AIF 计算的 TMRGlc 也无统计学差异。总之，在小动物模型中进行双 MRI-PET 药代动力学建模，仅需一个准确的 AIF 即可。
