MRI vs. CT. A ct (or cat) scan uses xrays and special computers to image the body. An MRI uses a combination of strong and weak magnets, radiofrequency coils and special computers to create images. There are certain body parts and disease processes that are better visualized with ct vs. Mri. Your doctor and/or the radiologist decide which test to perform based on many factors.
Radiation vs magneti. Cat scan are base on analyzing pictures from passing radiation through your body mri. Measure the effect of differents cells in a magnetic field.
Physics. The physical phenomena on which these imaging techniques are built are very different, each is best suited for different purposes. Cat scans are sophisticated x ray, they rely on the degree of absorption of gamma rays (bones, ca, other metals will contrast most). Mri is better for softer tissue imaging because it depends more on the behavior of hydrogen atoms and h2o in the strong magnetic field.
MRI/CT. A CT scan uses x-ray radiation to generate an image. An MRI uses magnetic fields "tuned" to the frequency of protons in the body. Since each scan essentially measures a different property of tissues in the body, they are complementary tests. That is why if one doesn't provide a definitive answer, often the other will be ordered.
What is the difference in diagnostics between mri, cat scan and colonoscopy? Which one is best for identifying problems?
Depends. Mri and ct scans are noninvasive imaging techniques. They have their own inherent advantages and disadvantages, and to compare them would be too complicated here. Colonoscopy is invasive, where a camera is extended via the rectum into the colon to see what the inside of the colon looks like, usually for cancer screening.
Big differences. Each of the tests you mentioned (mri, ct, colonoscopy) are used to diagnose different things. Therefore, depending on the problem you are trying to figure out, one test will be better than another. For example, colonoscopy is great for picking up colon polyps, but a regular ct would probably miss them. However, a ct would be great for appendicitis, and a colonoscopy would not be.