MRI information and comparisons
| Radiation exposure: | None. MRI machines do not emit ionizing radiation. |
| Cost: | MRI costs range from $1,200 to $4,000 (with contrast), which is usually more expensive than CT scans and X-rays, and most examining methods. |
| Time taken for complete scan: | Depending on what the MRI 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). |
| Effects on the body: | No biological hazards have been reported with the use of MRI. However, some may be allergic to the contrast dye, which is also inappropriate for those suffering from kidney or liver disorders. |
| Acronym for: | Magnetic Resonance Imaging. |
| Application: | Suited for Soft tissue evaluation, e.g., ligament and tendon injury, spinal cord injury, brain tumors, etc. |
| Scope of application: | MRI is more versatile than the X-Ray and is used to examine a large variety of medical conditions. |
| Ability to change the imaging plane without moving the patient: | MRI machines can produce images in any plane. Plus, 3D isotropic imaging also can also produce Multiplanar Reformation. |
| Details of bony structures: | Less detailed compared to X-ray |
| Principle used for imaging: | Uses large external field, RF pulse and 3 different gradient fields |
| Details of soft tissues: | Provides much more soft tissue detail than a CT scan. |
| Principle: | Body tissues that contain hydrogen atoms (e.g. in water) are made to emit a radio signal which are detected by the scanner. Search for "magnetic resonance" for physics details. |
| History: | First commercial MRI was available in 1981, with significant increase in MRI resolution and choice of imaging sequences over time. |
| Image specifics: | Demonstrates subtle differences between different kinds of soft tissues. |
| Intravenous Contrast Agent: | Very rare allergic reaction. Risk of reaction in those who have or have a history of kidney or liver disorders. |
| Comfort level for patient: | Anxiety, especially anxiety caused by claustrophobia, is common, as is tiredness or annoyance over having to stay still on a hard table for a long period of time. |
| Limitation for Scanning patients: | Patients with Cardiac Pacemakers, tattoos and metal implants are contraindicated due to possible injury to patient or image distortion (artifact). Patient over 350 lb may be over table's weight limit. Any ferromagnetic object may cause trauma/burn. |
| Detail: | While an MRI is good at seeing soft tissue, however, it is a very specific test. Therefore it is not a viable option when searching for issues of unknown origin. CT is typically preferred when searching for cause of pain with unknown origin. |