Sokoloff model, as in Sokoloff-Phelps paper (Annals of Neurology 1979, vol.6 No. 5) is

This  is the formula that was used by Dr. Wai Tsui (Mony's team). He sets k4=0.   So after that the expression could be rewritten:  alpha1 = 0,  alpha2 = k2+k3

This is exactly the formula used by Wai and is presently in FireVoxel Build 134 (the Anne was using for the abstract).

Now there is a second paper by Reivich (Journal of Cerebral Blood flow and Metabolism 5:179-192 1985), brought up by Fernando.  This paper references an earlier (Sokoloff 1977) paper: with

However, those 2 formulas are substantially different, which can be the easiest observe if we substitute k2=0 to both.  So which one should I use?

Fixing defect, when the 4D volume crop, the absolute values of times are lost and relative times are preserved.  This causes the problem for some registration functions.