Is MRI or CT better?

[scilearner]

Hello guys,

I have few questions

1. I know MRI is best for soft tissue masses? What does soft tissues mean? I searched on the internet and the definition is vague. Is it simply all the tissue apart from bone in the body, which means its includes organs such as liver. Or is it all supporting tissue in the body such as connective tissue.

2. If soft tissue includes organs such as liver, pancreas. Does this mean since MRI is best for soft tissue masses, it is always the best investigation for liver pathologies when given the choice of performing CT or MRI. I know this depends on the disease and in some cases biopsy, USS may be better options but I'm just asking if given the choice between CT and MRI.

3. I know CT is good for bones. But I read somewhere MRI spine is better than CT spine when detecting spinal fractures.

4. Also is MRI or PET scan better when finding for metasates of certain cancers.

5. Also is CT or MRI better for bones.

Thanks a lot

[fiveworlds]

MRI avoids the use of ionizing radiation. For this reason you can take many MRI scans but with the CT scan you are limited because of the risks to the patient.

[CharonY]

Soft tissue is generally anything that is not bone or other highly calcified structure. That being said the question is actually not quite trivial to answer. It depends highly on what you need to see and the amount of fine structure which is present. For example looking at bone marrow tumors MRI is as good or better than CT. Same is generally true for tumors in soft tissue. However, if you want to look at fractures, CT allows you to see them better. Same is true for calcific deposits.

Thus, often when fractures or other injuries are suspected CTs may be ordered over MRI. On the other hand, metanalyses showed that MRI was superior for diagnostics of liver lesions (Lee et al. Radiology 2015). Except for the cases where one is clearly superior to the other, the expertise of the readiologist will also play an important role. So both instruments have their respective value and are to a degree complimentary to each other.

[scilearner]

Thanks for all the replies. Charony answer was more what I was after