I've gone through a lot of forums, and i see that GPSMapEdit 1.0.66.7 can open NT formats (based on the experience of users). Not a version less or more, but this exact version. Said it's some kind of bug that processes the img file. But if your are lucky to have GPSMapEdit 1.0.66.7, kindly share, because I'm quite sure its of the internet. I have tried and tired...

Cheerio