👍

Honestly it is not easy, if not impossible, to tell them apart. In this particularly case, we went with arachnoid cyst first because it's much more common than web, and also it doesn't look like there was a definitive ventral herniation (again, very difficult to tell). We could have done CT myelogram first, but the surgeon went ahead and decompressed it, and confirmed it to be arachnoid cyst. Even with great resolution imaging, I don't think you can visualize the web/band directly.