What is the difference between the CT scan and magnetic resonance?

Unlike CT scans, which use X-rays, MRI scans use powerful magnetic fields and radio frequency pulses to produce detailed pictures of organs, soft tissues, bone and other internal body structures. Differences between normal and abnormal tissue is often clearer on an MRI image than a CT.

MRI is useful in multiplanar imaRegarding safety,

 MRI is a safer modality than CT, both the imaging system itself ging 

CT can outline bone inside the body very accurately, but MRI is more versatile than the X-Ray and is used to examine a large variety of medical conditions.

CT scan usually complets within 5 minutes. Actual scan time usually takes less than 30 seconds. Therefore, CT is less sensitive to the patient movement than MRI.  Whereas MRI, depending on what is looking for and where it is needing to look, the scan may be quick (finished in 10-15 minutes) or may take a long time (2 hours).

Physical principles: CT is basicly X-rays, and MR are corelations between magnetic fields.

1. C.T : SHOW US BONES CORRECTLY AND SOME SOFT TISSUE
2. M.R.I : SHOW US ANY THING WE NEED TO SEE IT INSIDE THE HUMEN BODY

MRI uses water molecules signal resonance which is non-radiating and is better use to evaluate soft tissue, differentiating normal and abnormal soft tissue, evaluate extension of disease in soft tissue and for early detection of clinically suspected stroke.  However, it is time consuming and expensive.

CT uses radiation to produce image, usefull in evaluation of haemorrhagic stroke, bone disease and staging.  It is readyly available, fast and less expensive.

In CT scan we use Xrays, and MRI we use Magnetic Field to produce images..

as like CT we have two dimensional images although in MRI we have 3 dimensional images 

MRI uses Magnetic field in Producing Image while CT scan uses Radiation 

MRI is preferred in evalation of soft tissue 

CT is advised as 1st aid of evaluation in some cases such as scan of post traumatic brain haemorrage 

ct is better in assessment of bone

• CT scans

  Radiation – Since CT scans are created by multiple x-rays, there is radiation exposure, although minimal. It is not usually appropriate during pregnancy.
• Uses – Excellent for looking at bones, but very good for soft tissues, especially with intravenous contrast dye.
• Cost – Usually less expensive than MRI
• Time – Very quick. The test only takes about 5 minutes, depending on the area that is being scanned.
• Patient comfort – The machine is very open, so concerns about confined space is rarely a problem.
• Reactions – The intravenous contrast rarely causes allergic reactions. It does have the potential to injure kidneys, especially with people who already have kidney problems or diabetes or those who are very dehydrated.
• Limitations – Patients who weigh more than 300 pounds may have to be sent to a location with a table designed to handle their weight.

• MRI

  • Radiation – None
  • Uses – Excellent for detecting very slight differences in soft tissues.
  • Cost – Often more expensive than CT scans.
  • Time – The time depends on the part of the body being examined and can range from 15 minutes up to 2 hours.
  • Patient comfort – The narrow tube can cause anxiety. Open MRI machines have been developed to handle patients who aren’t comfortable with the regular machine.
  • Reactions – Very rare allergic reactions to the IV contrast.
  • Limitations – Size of the tube may limit the size of the patient, although large patients may be handled with the open MRI machine. Certain metal objects implanted in the body, such as pacemakers, some prosthetic joints and rods and even some tattoos, may be affected by the magnetic field, preventing the test.

A CT scanner sends X-ray beams through the body as it moves through an arc taking many pictures. A CT scan sees different levels of density and tissues inside a solid organ, and can provide detailed information about the body, including the head (brain and its vessels, eyes, inner ear, and sinuses), chest (heart and lungs), skeletal system (neck, shoulders and spine), pelvis and hips, reproductive systems, bladder and gastrointestinal tract.

• Unlike CT scans, which use X-rays, MRI scans use powerful magnetic fields and radio frequency pulses to produce detailed pictures of organs, soft tissues, bone and other internal body structures. Differences between normal and abnormal tissue is often clearer on an MRI image than a CT. And while there is no radiation involved in an MRI scan, it can be a noisy exam and takes longer than a CT. A specially trained radiologist can interpret either scan, helping to achieve a quick and accurate diagnosis.