图像法获取犬^(18)F-FDG PET/CT显像的输入函数

Input functions derived from ^(18)F-FDG PET/CT imaging in canines

目的比较^(18)F-FDG PET 图像法和动脉采血法获取输入函数的差别,寻求图像法获取输入函数的最佳部位。方法 5条犬均进行股动脉连续采血和心腔及大血管^(18)F-FDG PET 动态显像,获得动脉血浆输入函数和心腔及大血管区域显像的输入函数,比较不同输入函数计算的曲线下面积(AUC)及通过 Patlak 方法计算犬心肌的抑制指数(Ki)。结果心腔和大血管^(18)F-FDG PET 图像获得的输入函数与动脉采血法计算的 AUC 有很好的相关性(r≥0.97),其中采用主动脉弓(AC)和降主动脉(DA)区域的输入函数获得的心肌 FDG 代谢 Ki 与动脉采血法获得的值一致(两者比值分别为1.0±0.1和1.1±0.1)。结论采用 AC 和 DA 区域获得输入函数较适合进行无创的定量分析。

Objective The input functions are of necessity in quantitative PET imaging. In this study the authors tried to derive non-invasively the input functions from canine ^18F-FDG PET/CT scans, as compared with standardized input functions determined invasively from serial arterial plasma sampling. Methods Five dogs underwent serial PET/CT scans using dynamic scanning protocol after ^18F-FDG administration. Meanwhile, continuous arteries blood samples were collected through catheters inserted into femoral arteries of the dogs. Image derived input functions （IDIF） were obtained using ROI defined on dynamic PET/CT images over various cardiovascular structures such as left ventricle （ LV ）, right ventricle （ RV ）, right atria （RA）, aortic arch （AC）, ascending aorta （AA） and descending aorta （DA）. Area under curve （AUC） method was used to calculate each input function from arterial plasma sampling. Canine myocardial inhibition constant （Ki） values were estimated using Patlak graphical analyses. Results IDIF from ^18F-FDG PET/CT scans were significantly correlated with input functions derived from arterial plasma sampling using AUC （r≥0.97）. When AC and DA regions were chosen for the calculation, the mean Ki estimated thereby using IDIF were almost identical to those using input functions from artery blood sampling analyses （ the ratios between two sets of Ki being 1.0 ± 0.1 and 1.1 ± 0.1 respectively）. Conclusion It might be feasible to use IDIF derived from ROIs over AC and DA on a dynamic ^18 F-FDG PET/CT scan, as a non-invasive procedure, for quantitative analyses.