What is the difference between CT scan and MRI? indication and contraindications?

Answer 1

CT Scan: Practically speaking, X rays are used, and are indicated in soft tissue evaluation e.g.hematoma of brain, differentiate between a cyst and solid mass, cardiac scanning, etc.
Contraindications are the same as that of Xray e.g. pregnancy.

MRI: A strong magnetic field is applied, mostly indicated in bony outline of vertebras, thecal matter, e.g in osteoarthritis.
Contraindications: PPM patients, Austin Moore prosthesis etc.

In combination with Nuclear Isotopes both, are used in diagnosis, demarcation of field for surgery, palliative treatment of joint pain, Boron for Ca brain treatment.

In short you can see physiology and pathology at work.

Answer 2

They look at different things. CT is more like Xrays that look at bones and tissues in a multiple plane but involves radiation exposure. It is very fast and can look at many structures in several slices. It is widely available on an emergent basis as well. The CT scanner uses X-rays, a type of ionizing radiation, to acquire its images, making it a good tool for examining tissue composed of elements of a relatively higher atomic number than the tissue surrounding them, such as bone and calcifications (calcium based) within the body (carbon based flesh), or of structures (vessels, bowel).
MRI is primarily used in medical imaging to demonstrate pathological or other physiological alterations of living tissues
MRI, on the other hand, uses non-ionizing radio frequency (RF) signals to acquire its images and is best suited for non-calcified tissue.

CT may be enhanced by use of contrast agents containing elements of a higher atomic number than the surrounding flesh (iodine, barium). Contrast agents for MRI are those which have paramagnetic properties. One example is gadolinium.

Both CT and MRI scanners can generate multiple two-dimensional cross-sections (slices) of tissue and three-dimensional reconstructions. Unlike CT, which uses only X-ray attenuation to generate image contrast, MRI has a long list of properties that may be used to generate image contrast. By variation of scanning parameters, tissue contrast can be altered and enhanced in various ways to detect different features.
MRI can generate cross-sectional images in any plane (including oblique planes). CT was limited to acquiring images in the axial (or near axial) plane in the past. (CAT scans). However, the development of multi-detector CT scanners with near-isotropic resolution, allows the CT scanner to produce data that can be retrospectively reconstructed in any plane with minimal loss of image quality.
For purposes of tumor detection and identification, MRI is generally superior[ However, CT usually is more widely available, faster, much less expensive, and may be less likely to require the person to be sedated or anesthetized.

Answer 3

Find your answers at these two links. Both are from MedlinePlus.

CT Scan
http://www.nlm.nih.gov/medlineplus/ctscans.html

MRI
http://www.nlm.nih.gov/medlineplus/mriscans.html

Terry

I'm not a doctor, so I gave you good sources.