Hong Young T, Beech John S, Smith Rob, Baron Jean-Claude, Fryer Tim D
Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.
J Cereb Blood Flow Metab. 2011 Feb;31(2):648-57. doi: 10.1038/jcbfm.2010.141. Epub 2010 Aug 25.
In this study, we show a basis function method (BAFPIC) for voxelwise calculation of kinetic parameters (K(1), k(2), k(3), K(i)) and blood volume using an irreversible two-tissue compartment model. BAFPIC was applied to rat ischaemic stroke micro-positron emission tomography data acquired with the hypoxia tracer [(18)F]fluoromisonidazole because irreversible two-tissue compartmental modelling provided good fits to data from both hypoxic and normoxic tissues. Simulated data show that BAFPIC produces kinetic parameters with significantly lower variability and bias than nonlinear least squares (NLLS) modelling in hypoxic tissue. The advantage of BAFPIC over NLLS is less pronounced in normoxic tissue. K(i) determined from BAFPIC has lower variability than that from the Patlak-Gjedde graphical analysis (PGA) by up to 40% and lower bias, except for normoxic tissue at mid-high noise levels. Consistent with the simulation results, BAFPIC parametric maps of real data suffer less noise-induced variability than do NLLS and PGA. Delineation of hypoxia on BAFPIC k(3) maps is aided by low variability in normoxic tissue, which matches that in K(i) maps. BAFPIC produces K(i) values that correlate well with those from PGA (r(2)=0.93 to 0.97; slope 0.99 to 1.05, absolute intercept <0.00002 mL/g per min). BAFPIC is a computationally efficient method of determining parametric maps with low bias and variance.
在本研究中，我们展示了一种基于基函数的方法（BAFPIC），用于使用不可逆双组织隔室模型体素级计算动力学参数（K(1)、k(2)、k(3)、K(i)）和血容量。BAFPIC应用于用缺氧示踪剂[(18)F]氟米索硝唑获取的大鼠缺血性中风微型正电子发射断层扫描数据，因为不可逆双组织隔室建模能很好地拟合缺氧和正常组织的数据。模拟数据表明，在缺氧组织中，BAFPIC产生的动力学参数的变异性和偏差明显低于非线性最小二乘法（NLLS）建模。在正常组织中，BAFPIC相对于NLLS的优势不太明显。由BAFPIC确定的K(i)的变异性比Patlak-Gjedde图形分析（PGA）低多达40%，偏差也更低，但中高噪声水平下的正常组织除外。与模拟结果一致，真实数据的BAFPIC参数图比NLLS和PGA受噪声诱导的变异性更小。BAFPIC的k(3)图上缺氧区域的划定得益于正常组织中低变异性，这与K(i)图中的情况相匹配。BAFPIC产生的K(i)值与PGA得到的值具有良好的相关性（r(2)=0.93至0.97；斜率0.99至1.05，绝对截距<0.00002 mL/g每分钟）。BAFPIC是一种计算效率高的方法，可用于确定具有低偏差和方差的参数图。
