about mask

Dear experts,

I have a question about making mask. I want to make a mask according to the result of one sample t-test, including significant regions from one sample t-test both in patient and control groups. In the image calculator the expression is (i1>0)+(i2>0)>0. But this only results in a image that includes regions significantly higher than the mean value. What if I also want to include regions lower than the mean value? In the course video I caught that the expression could be (i1~0)+(i2~0)>0, but I got an error with this expression. What is the right expression format?

Thank you!

Best wishes.

Charlotte