To install dcm2niix, run the following command in macOS terminal (Applications->Utilities->Terminal)
sudo port install dcm2niix
To see what files were installed by dcm2niix, run:
port contents dcm2niix
To later upgrade dcm2niix, run:
sudo port selfupdate && sudo port upgrade dcm2niix
Reporting an issue on MacPorts Trac
The MacPorts Project uses a system called Trac to file tickets to report bugs and enhancement requests.
Though anyone may search Trac for tickets, you must have a GitHub account in order to login to Trac to create tickets.