5 doctors weighed in:

Are there times when both CT and MRI procedures may be necessary? What are the main differences, and is one more risky than the others?

5 doctors weighed in
Dr. Neil Halin
Radiology - Interventional
2 doctors agree

In brief: Yes

There are times when both are used.
CT uses xrays to make the images, MRI uses both magnetic waves and radio waves. Both have sensitivities that make them good for certain things and worse for others. We often get both because they tell different things. Since CT uses x-rays we try to keep that in mind so that we don't irradiate people needlessly. CT scans can theoretically increase cancer risks.

In brief: Yes

There are times when both are used.
CT uses xrays to make the images, MRI uses both magnetic waves and radio waves. Both have sensitivities that make them good for certain things and worse for others. We often get both because they tell different things. Since CT uses x-rays we try to keep that in mind so that we don't irradiate people needlessly. CT scans can theoretically increase cancer risks.
Dr. Neil Halin
Dr. Neil Halin
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Dr. John Fung
Surgery
1 doctor agrees

In brief: CT

Ct and MRI are cross sectional imaging techniques which have revolutionized the ability to make diagnoses that previously required invasive studies.
Ct scans utilize ionizing radiation, like a chest x-ray. Mri scans utilize a very powerful magnet field that causes water and other molecules to line up like a compass in a magnetic field. When the magnetic field is released, the energy released by the movement of molecules leads to distinct signals that can be analyzed and used to reconstruct an image. In both scans, contrast agents can be used to increase the ability to look at specific structures, such as blood vessels and other hollow structures. While both scans provide internal images, each type of scan has some distinct advantage over the other. Occasionally it may be necessary to get both scans, but in general, depending on the situation, one or the other is generally used.

In brief: CT

Ct and MRI are cross sectional imaging techniques which have revolutionized the ability to make diagnoses that previously required invasive studies.
Ct scans utilize ionizing radiation, like a chest x-ray. Mri scans utilize a very powerful magnet field that causes water and other molecules to line up like a compass in a magnetic field. When the magnetic field is released, the energy released by the movement of molecules leads to distinct signals that can be analyzed and used to reconstruct an image. In both scans, contrast agents can be used to increase the ability to look at specific structures, such as blood vessels and other hollow structures. While both scans provide internal images, each type of scan has some distinct advantage over the other. Occasionally it may be necessary to get both scans, but in general, depending on the situation, one or the other is generally used.
Dr. John Fung
Dr. John Fung
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1 comment
Dr. Neil Halin
CT is very good at visualizing anatomy with high resolution. It can see calcifications well (such as in blood vessels or stones). MRI is better at more physiological things such as finding some kinds of tumors, looking at functional brain imaging, etc. MRI contrast is different from CT contrast and often if someone is allergic to CT contrast they can have imaging with MR.
Dr. Michael Gabor
Diagnostic Radiology

In brief: Yes,

both may be indicated in certain situations.
Each produces images based on different tissue characteristics. CT uses xray radiation to detect differences in absorption or "attenuation" between tissues, and MRI uses magnetic fields and radiofrequency pulses to measure the behavior of hydrogen atoms in different tissues. CT risks relate to theoretical cancer risks from cumulative exposure.

In brief: Yes,

both may be indicated in certain situations.
Each produces images based on different tissue characteristics. CT uses xray radiation to detect differences in absorption or "attenuation" between tissues, and MRI uses magnetic fields and radiofrequency pulses to measure the behavior of hydrogen atoms in different tissues. CT risks relate to theoretical cancer risks from cumulative exposure.
Dr. Michael Gabor
Dr. Michael Gabor
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