How to identify noise in medical image?

in preprocessing of an image, first we have to identify whether an image having noise or not. if so we have use filtering technique to reduce noise effects in image. first of all how to identify noise in an image? is there any measure for identifying noise especially for medical image for further procesing namely segmentation?

Answer 1

[Mohammad Abouali]

May be this could be useful in your case

Noise Level Estimation from a single image

or this

How noisy are your images