A cath lab is an examination room with diagnostic imaging equipment where doctors perform minimally invasive procedures to diagnose and treat a wide range of cardiovascular issues. In the cath lab, doctors use fluoroscopy to see catheters move through vessels and arteries, and from there can deploy a variety of methods to diagnose and treat various diseases.
One thing that stands a cath lab apart from other modalities is the image to diagnosis to treatment timeline. Modalities such as MRI, CT, Rad Rooms, etc. are diagnostics that provide data to enable treatments. In a cath lab, they are diagnosing and treating, often in the same study.
You'll find cath labs in facilities like Hospitals, Imaging Centers, Office Based Labs, and Ambulatory Surgery Centers.