Mount old MS-DOS .img on Linux

Question

Is there a way to mount an old .img file that's most likely a copy of a CD-ROM made for MS-DOS on Linux? All attempts have failed yet. file sees it just as "data", fdisk -l only says

646,75 MiB, 678163456 bytes, 1324538 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

Mounting with either mount -o loop and mount -o loop,offset=512 fails. I can mount it with losetup to any /dev/loop-device, but I can't mount that anywhere. for mount I get the output

wrong fs type, bad option, bad superblock on /dev/loop0, missing codepage or helper program, or other error.
       dmesg(1) may have more information after failed mount system call.

and dmseg tells me

[39452.042543] loop0: detected capacity change from 0 to 1324537
[39452.051688] EXT4-fs (loop0): VFS: Can't find ext4 filesystem
[39452.051889] EXT4-fs (loop0): VFS: Can't find ext4 filesystem
[39452.051986] EXT4-fs (loop0): VFS: Can't find ext4 filesystem
[39452.052096] FAT-fs (loop0): bogus number of reserved sectors
[39452.052100] FAT-fs (loop0): Can't find a valid FAT filesystem

The first lines of the hexdump are:

00000000  00 ff ff ff ff ff ff ff  ff ff ff 00 00 02 00 01  |................|
00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|

What can I do to access the content?

Answer 1

My file was in the Alcohol 120% proprietary format called MDF.

I found the tool mdf2iso (native Linux CLI tool) to convert the image into an ISO and I could afterwards mount it.