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Gould, RT-(R)(MR)(ARRT), Todd A. "How MRI Works." 01 April 2000. HowStuffWorks.com. <http://health.howstuffworks.com/mri.htm> 11 May 2008.
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MRI Scan
If you have ever seen an MRI machine, you know that the basic design used in most is a giant cube. The cube in a typical system might be 7 feet tall by 7 feet wide by 10 feet long (2 m by 2 m by 3 m), although new models are rapidly shrinking. There is a horizontal tube running through the magnet from front to back. This tube is known as the bore of the magnet. The patient, lying on his or her back, slides into the bore on a special table. Whether or not the patient goes in head first or feet first, as well as how far in the magnet they will go, is determined by the type of exam to be performed. MRI scanners vary in size and shape, and newer models have some degree of openness around the sides, but the basic design is the same. Once the body part to be scanned is in the exact center or isocenter of the magnetic field, the scan can begin.In conjunction with radio wave pulses of energy, the MRI scanner can pick out a very small point inside the patient's body and ask it, essentially, "What type of tissue are you?" The point might be a cube that is half a millimeter on each side. The MRI system goes through the patient's body point by point, building up a 2-D or 3-D map of tissue types. It then integrates all of this information together to create 2-D images or 3-D models.
MRI provides an unparalleled view inside the human body. The level of detail we can see is extraordinary compared with any other imaging modality. MRI is the method of choice for the diagnosis of many types of injuries and conditions because of the incredible ability to tailor the exam to the particular medical question being asked. By changing exam parameters, the MRI system can cause tissues in the body to take on different appearances. This is very helpful to the radiologist (who reads the MRI) in determining if something seen is normal or not. We know that when we do "A," normal tissue will look like "B" -- if it doesn't, there might be an abnormality. MRI systems can also image flowing blood in virtually any part of the body. This allows us to perform studies that show the arterial system in the body, but not the tissue around it. In many cases, the MRI system can do this without a contrast injection, which is required in vascular radiology.
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Please copy/paste the following text to properly cite this How Stuff Works article:
Gould, RT-(R)(MR)(ARRT), Todd A. "How MRI Works." 01 April 2000. HowStuffWorks.com. <http://health.howstuffworks.com/mri.htm> 11 May 2008.
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Heel Pain Hemolytic Crisis Hepatomegaly Heterochromia Hiccups Hip Pain Hoarseness Or Changing Voice Hump Behind The Shoulders Hyperactivity Hyperelastic Skin Hypermobile Joints Hyperventilation Hypotonia Impaired Smell Increased Head Circumference Indigestion Infantile Reflexes Intercostal Retractions Intertrigo Irritability Itching Jaundice (Yellow Skin) Joint Pain Joint Swelling Knee Pain Leg Pain Lichenified Limited Range Of Motion Lordosis Low Nasal Bridge Lower Back Pain Macule Malaise Memory Loss Metopic Ridge Microcephaly Micrognathia Morbid Obesity Morning Sickness Moro Reflex Motormental Retardation Mouth Sores Muscle Aches Muscle Atrophy Muscle Cramps Muscle Function Loss Muscle Twitching Nail Abnormalities Nasal Congestion Nasal Discharge Nasal Flaring Natal Teeth Nausea And Vomiting Neck Lumps Neck Pain Night Blindness Nightmares Nikolsky’s Sign Nipple Discharge Nodules Nosebleed Numbness And Tingling Obesity Opisthotonos Pain During Sexual Intercourse Painful Menstrual Periods Painful Urination Pale or Clay-Colored Stools Paleness Papule Patches Patchy Skin Color Pectus Carinatum Pectus Excavatum Penis Pain Photophobia Pilonidal Dimple Pinna Abnormalities And Low-set Ear... Point Tenderness Polydactyly Polyhydramnios Poor Feeding In Infants Preauricular Tag Or Pit Premenstrual Breast Tenderness and ... Prognathism Pupils That Are Different Sizes Purpura Pustules Rapid Shallow Breathing Rash in a Child Under 2 Years Rashes Rib Cage Pain Ridged Sutures Scales Scrotal Swelling Seizures Sensorineural Deafness Separated Sutures Shin Splints Short Philtrum Short Stature Shoulder Pain Simian Crease Skeletal Limb Abnormalities Skin Blushing/flushing Skin Discoloration Skin Lumps Skin Turgor Sleeping Difficulty Sneezing Snoring Sore Throat Spasticity Speech Impairment (adult) Splenomegaly Splinter Hemorrhages Strange Behavior Stress And Anxiety Striae Subcutaneous Emphysema Sunburn Sunken Fontanelles Supernumerary Nipples Swallowing Difficulty Swallowing Pain Or Burning Sweating Sweating Decrease Swelling Swollen Glands Swollen Gums Taste Impairment Telangiectasia Tenesmus Testicle Lump Testicle Pain Tinnitus Tongue Problems Tooth Discoloration Toothaches Ulcers Uncontrollable Eye Movements Uncontrollable Movement Uncontrolled Or Slow Movement Uncoordinated Movement Unpredictable Or Jerky Movement Urinary Incontinence Urine Discoloration Vaginal Bleeding Between Periods Vaginal Bleeding In Pregnancy Vaginal Discharge Vaginal Itching Vesicles Vision Problems Vomiting Blood Walking Abnormalities Watery Eyes Weak or Absent Pulse Weakness Webbing Of The Fingers Or Toes Weight Gain Weight Loss Wheezing White Spots in the Pupil Whitehead Widely Spaced Teeth Wrinkles Wrist Pain Yawning