Knee MRI
Magnetic resonance imaging (MRI) uses a magnetic field, radio waves and a computer to create detailed image slices (cross sections) of the knee. These images allow the physician to evaluate different types of body tissue, including the meniscus (shock absorbers in the knee joint), cartilage, ligaments and tendons, as well as distinguish normal, healthy tissue from diseased tissue.
If patients are claustrophobic (fearful of small, enclosed areas) or experience pain when lying on the back for more than 30 minutes, the doctor may prescribe a relaxant or pain medication t help them through the procedure.
During the exam, the patient is positioned on the scanning table feet first with arms at the side. Coils (special devices to improve image quality) may be placed on or around the knee area. The scanning table slides into the magnet, covering the lower body. During the scan patients do not feel anything, but they hear intermittent humming, thumping, clicking and knocking sounds. Earplugs are provided to help mask the noise.
In some cases, the radiologist requests a contrast agent (dye) to improve the quality of the images. Before the exam, patients must inform the technologist, radiology nurse and/or physician if they have allergies, are pregnant or are nursing. Patients may eat and drink before the exam. The contrast agent is injected into a vein in the arm, which may cause a cool sensation. As pictures are taken, the patient must hold very still, and in some cases, hold their breath. The technologist is always able to see and hear the patient during the approximately 45- to 60-minute exam.
