Any advice on getting rid of intrusive thoughts?

Sometimes when I am thinking, these bad thoughts come into my mind, specifically images. I would rather elaborate not elaborate what the images are but they are all connected by a single object.

I have tried meditation, and while I feel at peace for a few hours after meditating, the thoughts haven't really left long-term or gone down in frequency. Maybe I am meditating wrong. I am blindsided every time the thoughts appear.

Anyone have any experience with this?