Kudomi Nobuyuki, Koivuviita Niina, Liukko Kaisa E, Oikonen Vesa J, Tolvanen Tuula, Iida Hidehiro, Tertti Risto, Metsärinne Kaj, Iozzo Patricia, Nuutila Pirjo
Turku PET Centre, University of Turku, Turku, Finland.
Eur J Nucl Med Mol Imaging. 2009 Apr;36(4):683-91. doi: 10.1007/s00259-008-0994-8. Epub 2008 Dec 3.
The quantitative assessment of renal blood flow (RBF) may help to understand the physiological basis of kidney function and allow an evaluation of pathophysiological events leading to vascular damage, such as renal arterial stenosis and chronic allograft nephropathy. The RBF may be quantified using PET with H(2)(15)O, although RBF studies that have been performed without theoretical evaluation have assumed the partition coefficient of water (p, ml/g) to be uniform over the whole region of renal tissue, and/or radioactivity from the vascular space (V(A). ml/ml) to be negligible. The aim of this study was to develop a method for calculating parametric images of RBF (K(1), k(2)) as well as V(A) without fixing the partition coefficient by the basis function method (BFM).
The feasibility was tested in healthy subjects. A simulation study was performed to evaluate error sensitivities for possible error sources.
The experimental study showed that the quantitative accuracy of the present method was consistent with nonlinear least-squares fitting, i.e. K(1,BFM)=0.93K(1,NLF)-0.11 ml/min/g (r=0.80, p<0.001), k(2,BFM)=0.96k(2,NLF)-0.13 ml/min/g (r=0.77, p<0.001), and V(A,BFM)=0.92V(A,NLF)-0.00 ml/ml (r=0.97, p<0.001). Values of the Akaike information criterion from this fitting were the smallest for all subjects except two. The quality of parametric images obtained was acceptable.
The simulation study suggested that delay and dispersion time constants should be estimated within an accuracy of 2 s. V(A) and p cannot be neglected or fixed, and reliable measurement of even relative RBF values requires that V(A) is fitted. This study showed the feasibility of measurement of RBF using PET with H(2)(15)O.
肾血流量（RBF）的定量评估有助于理解肾功能的生理基础，并能够评估导致血管损伤的病理生理事件，如肾动脉狭窄和慢性移植肾肾病。虽然已经有使用H(2)(15)O进行PET的RBF研究，但在没有理论评估的情况下进行的这些研究假定水的分配系数（p，ml/g）在整个肾组织区域是均匀的，和/或血管空间的放射性（V(A)，ml/ml）可忽略不计。本研究的目的是开发一种通过基函数法（BFM）计算RBF（K(1)，k(2)）以及V(A)的参数图像的方法，而不固定分配系数。
在健康受试者中测试了可行性。进行了一项模拟研究以评估可能误差来源的误差敏感性。
实验研究表明，本方法的定量准确性与非线性最小二乘法拟合一致，即K(1,BFM)=0.93K(1,NLF)-0.11 ml/min/g（r=0.80，p<0.001），k(2,BFM)=0.96k(2,NLF)-0.13 ml/min/g（r=0.77，p<0.001），以及V(A,BFM)=0.92V(A,NLF)-0.00 ml/ml（r=0.97，p<0.001）。除两名受试者外，所有受试者的该拟合的赤池信息准则值最小。获得的参数图像质量可接受。
模拟研究表明，延迟和弥散时间常数应在2 s的精度内估计。V(A)和p不能被忽略或固定，并且即使是相对RBF值的可靠测量也需要拟合V(A)。本研究表明了使用H(2)(15)O进行PET测量RBF的可行性。
