MDX is the go-to visualization software for ROI_PAC files, and this post explains how to get it working on a Mac. You can see about installing alternative software on this post

MDX is tricky to obtain,,, here is one place.

You'll need some dated open motif libraries to run it. Fortunately, with Homebrew see this post, it's not hard to get it working on a Mac:

brew install lesstif

Assuming you have obtained mdx_190_79_03.tar

tar -xzf mdx_190_79_03.tar
cd mdx_190_79_03

Change the following two lines in Makemdx_gfortran:

XINC = -I/usr/X11R6/include/ -I/opt/X11/include/
XLIB = -L/opt/X11/lib  -lXm -L/usr/X11R6/lib -lXt -lX11

And run:

make -f Makemdx_gfortran

Now just add the MDX environment variable to SAR_CONFIG and system PATH (e.g. export PATH=/Users/scott/Software/mdx_190_79_03/mdx:$PATH). Assuming you have the ROI_PAC test data, you can see an image with the following command. More details on using MDX are here.