I think someone may be mixing-up the FLAIR and T1-weighted post-gadolinium images. FLAIR images often reveal many bright lesions, but post-gadolinium sequences may show a couple, if any. I've *never* seen even a single enhancing MS lesion that wasn't seen on a FLAIR sequence prior to contrast injection.

As for what else they could be - my advice is, don't try to learn this stuff piecemeal; it's too easy to misinterpret what you're reading when you take fragments of information out of context and without a firm foundation in medical imaging.