Tal-

MRIcron just helps you draw the lesion. You will want to use a different tool for statistics. For ANCOVA, you would want to use VLSM, and should direct your questions to that group https://aphasialab.org/vlsm/

Another option would be to conduct a permutation-thresholded Freedman-Lane analysis using NiiStat
  https://www.nitrc.org/plugins/mwiki/index.php/niistat:MainPage
For this, your Excel file would look like this

ID PD AGE IQ
C1 0 25 98
C2 0 36 92
C3 0 37 99
C4 0 38 102
P1 1 39 104
P2 1 30 100
P3 1 50 98
P4 1 33 96

And your analysis would be a [1 0 0] analysis. Since NiiStat is designed for lesion work, we tend to assume that most brain injury impairs behavior, so we have conduct a one-tailed test. Based on the distribution of the data, the two tails may not be symmetrical, so you can have different scores for the positive end of the tail and the negative. I am a huge fan of permutation thresholding, it solves a lot of ills in Neuroimaging.

By the way, NiiStat should report Z-scores not F or T scores. With F and T scores, you need to know the degrees of freedom to interpret them. Computers are extremely efficient at transforming F/T scores to z-scores. Humans are much less good at this. So I let the computers do the hard work of converting the statistical values to this intuitive metric.