and CT are very different and used for different needs and
reasons; both are valuable and both have specific applications;
they are not interchangeable and one is not a better test than
the other for all things. The decision whether to use one or the
other is based according to the density of the body tissue that
needs to be seen. Softer tissues that have more water molecules
or hydrogen atoms in them are better seen by MRI because of the
physics used. This is what an MR image of the brain looks like.
Body tissue that is composed of a greater number of hydrogen
atoms are seen well using MR. Thus, MR imaging shows us the
spinal cord, and tendons and ligaments in the knee and shoulder
and brain tissue well but not the skull bone. Brain tissue that
is dying from loss of blood supply and tumors of the brain are
best seen on MR imaging. Neurological diseases of the brain,
like Multiple Sclerosis, are detectable on MR imaging and
present as plaque deposits on the brain surface. This makes MRI
the modality used to l