What are the similarities and differences between MRI machines and PET scan?

Answer 1

The differences between the two relate to the different ways that each machine produces images of the brain (although images of different body parts can be acquired as well).

An MRI machine contains a huge "supercooled" cylindrical magnet. You sit inside this magnet and the techs put earphones on you (because of the noise). You lie down and keep still while the magnetic field is changed (which makes sounds like hammers banging on hard plastic!) to produce an image. In MRI, water molecules give off radio signals which are converted into high resolution images that look like this http://www.mr-tip.com/exam_gifs/brain_mri_transversal_t1_001.jpg

Here is a picture of an MRI machine http://www.mcmcbr.com/pix/mri_large.jpg

In a PET scan, you are injected with a harmless solution (e.g. glucose in sterile saline) and then wait until the sugar has moved through the bloodsream to be used by different parts of the brain before going into the scanner. The glucose molecules are special because they have been treated so they emit radiation (positrons) and the PET scanner detects these positrons to provide a picture that looks like this http://www.nia.nih.gov/NR/rdonlyres/81D409B2-F2A8-470A-9AA6-1E2DDE7A9CEC/0/PET20YEAROLD_HIGH.JPG

Here is a picture of a PET scanner http://upload.wikimedia.org/wikipedia/commons/thumb/b/b8/ECAT-Exact-HR--PET-Scanner.jpg/300px-ECAT-Exact-HR--PET-Scanner.jpg

As you can see, an MRI machine and a PET scanner look very similar; only the MRI machines contain a magnet. A CT scanner also looks similar, but uses X-rays to acquire images.

As you can see, the MRI image provides very detailed images, whereas the PET image is quite "fuzzy" (i.e. has a much lower resolution), but shows how active certain regions of the brain are.

Answer 2

Pet Scan Machine Picture

Answer 3

PET scan shows brain use, making a color coded picture of it MRI scan shows physical brain structure An interesting point that illustrates this difference, is an MRI of a dead brain will look the same as an MRI of a living one. A PET of a dead brain will be all black, while a living one will have various lit up places

Answer 4

MRI machine is able to obtain detailed anatomic images (structure) by looking at the protons in each atom of your body WHILE the PET shows molecular function and activity not structure.MRI uses a magnetic field WHILE Pet Scan uses positron-emitting molecules.

Answer 5

SIMILARITIES:
>>Both are diagnostic tools to non-invasively (non-surgically) look inside the body.
>>Both are used based on the principle that certain things happen to atoms in our bodies when they absorb energy.
>>Both have a close coach structure.
>>Both can construct a three dimensional image.

DIFFERENCES:
>>MRI machine is able to obtain detailed anatomic images (structure) by looking at the protons in each atom of your body WHILE the PET shows molecular function and activity not structure.
>>MRI uses a magnetic field WHILE Pet Scan uses positron-emitting molecules.