Is 1.5 filum terminale considered thick?

Forget it.

The position of the cone is half to two vertebral bodies lower than the normal, the filum terminale is only slightly thickened, and the diameter of the filum terminale is greater than 1.5 mm. This mild thickening of the filum terminale is difficult to determine on MR. So the filament terminale is 1.5mm thick.

The filum terminale is a non-nervous spinal pial filament that connects the end of the spinal conus and the dorsal side of the caudal vertebral body.