Hi there, 
I am trying to generate some tumor-free FLAIR images using TumorSim.
(The goal is to generate some ground truth healthy MRI data to compare with the corresponding
images with tumors.)  Look like the program expects a "correct" tumor seed to work
(I try to cheat the program with an empty seed, but without luck. It gave the warning about the
bad seed and crashed after running for a little while ). 

I am wondering is there a simple way that I could skip the step of "planting" tumors into the image?
Thanks a lot!

-best,
Xiaoxiao