Whats the difference between MRI & cat scan ?!
Question: Whats the difference between MRI & cat scan .?
and how are they different.Health Question & Answer
Answers:
Cat scans are a specialized type of x-ray. The patient lies down on a couch which slides into a large circular opening. The x-ray tube rotates around the patient and a computer collects the results. These results are translated into images that look like a "slice" of the person.
Sometimes a radiologist will decide that contrast agents should be used. Contrast agents are iodine based and are absorbed by abnormal tissues. They make it easier for the doctor to see tumors within the brain tissue. There are some (rare) risks associated with contrast agents and you should make sure that you discuss this with the doctor before arriving for the examination.
CT is very good for imaging bone structures. In fact, it's usually the imaging mode of choice when looking at the inner ears. It can easily detect tumors within the auditory canals and can demonstrate the entire cochlea on most patients.
MRI is a completely different animal! Unlike CT it uses magnets and radio waves to create the images. No x-rays are used in an MRI scanner.
The patient lies on a couch that looks very similar the ones used for CT. They are then placed in a very long cylinder and asked to remain perfectly still. The machine will produce a lot of noise and examinations typically run about 30 minutes.
The cylinder that you are lying in is actually a very large magnet. The computer will send radio waves through your body and collect the signal that is emitted from the hydrogen atoms in your cells. This information is collected by an antenna and fed into a sophisticated computer that produces the images. These images look similar to a CAT scan but they have much higher detail in the soft tissues. Unfortunately, MRI does not do a very good job with bones.
One of the great advantages of MRI is the ability to change the contrast of the images. Small changes in the radio waves and the magnetic fields can completely change the contrast of the image. Different contrast settings will highlight different types of tissue.
Another advantage of MRI is the ability to change the imaging plane without moving the patient. If you look at the images to the left you should notice that they look very different. The top two images are what we call axial images. This is what you would see if you cut the patient in half and looked at them from the top. The image on the bottom is a coronal image. This slices the patient from front to back. Most MRI machines can produce images in any plane. CT can not do this.
Contrast agents are also used in MRI but they are not made of iodine. There are fewer documented cases of reactions to MRI contrast and it is considered to be safer than x-ray dye. Once again, you should discuss contrast agents with your physician before you arrive for the examination.Health Question & Answer
Sometimes a radiologist will decide that contrast agents should be used. Contrast agents are iodine based and are absorbed by abnormal tissues. They make it easier for the doctor to see tumors within the brain tissue. There are some (rare) risks associated with contrast agents and you should make sure that you discuss this with the doctor before arriving for the examination.
CT is very good for imaging bone structures. In fact, it's usually the imaging mode of choice when looking at the inner ears. It can easily detect tumors within the auditory canals and can demonstrate the entire cochlea on most patients.
MRI is a completely different animal! Unlike CT it uses magnets and radio waves to create the images. No x-rays are used in an MRI scanner.
The patient lies on a couch that looks very similar the ones used for CT. They are then placed in a very long cylinder and asked to remain perfectly still. The machine will produce a lot of noise and examinations typically run about 30 minutes.
The cylinder that you are lying in is actually a very large magnet. The computer will send radio waves through your body and collect the signal that is emitted from the hydrogen atoms in your cells. This information is collected by an antenna and fed into a sophisticated computer that produces the images. These images look similar to a CAT scan but they have much higher detail in the soft tissues. Unfortunately, MRI does not do a very good job with bones.
One of the great advantages of MRI is the ability to change the contrast of the images. Small changes in the radio waves and the magnetic fields can completely change the contrast of the image. Different contrast settings will highlight different types of tissue.
Another advantage of MRI is the ability to change the imaging plane without moving the patient. If you look at the images to the left you should notice that they look very different. The top two images are what we call axial images. This is what you would see if you cut the patient in half and looked at them from the top. The image on the bottom is a coronal image. This slices the patient from front to back. Most MRI machines can produce images in any plane. CT can not do this.
Contrast agents are also used in MRI but they are not made of iodine. There are fewer documented cases of reactions to MRI contrast and it is considered to be safer than x-ray dye. Once again, you should discuss contrast agents with your physician before you arrive for the examination.Health Question & Answer
MRI:
More expensive
Great image resolution of soft tissue
Uses a big magnet and noninvasive (so far)
Loud bangs
Exclusion: claustrophobics, metal in the body
CT:
Cheaper & relatively quick procedure
OK image resolution overall
X-ray & must inject a contrast dye
But good thing is the contrast dye can image calcium deposits in the brain
No major exclusions (except maybe allergy to the dye)Health Question & Answer
More expensive
Great image resolution of soft tissue
Uses a big magnet and noninvasive (so far)
Loud bangs
Exclusion: claustrophobics, metal in the body
CT:
Cheaper & relatively quick procedure
OK image resolution overall
X-ray & must inject a contrast dye
But good thing is the contrast dye can image calcium deposits in the brain
No major exclusions (except maybe allergy to the dye)Health Question & Answer