Magnetic Resonance Imaging (MRI)
Magnetic resonance uses a large circular magnet and radio frequencies to generate signals from atoms in the body. These signals are used to construct images of the brain and body organs.
The MRI machine looks like a large box with an opening in the center. A technician takes you to the scanning table, which resembles a narrow bed, and positions you for the test.
During the procedure, you hear several series of loud, repetitive pulsing noises. These noises are harmless and indicate that the machine is working. It is particularly important to remain completely still during these sequences of noises because the MRI machine is obtaining images at these times.
An entire MRI exam may take from 20 minutes to 1.5 hours, depending on the type of information required by the radiologist and your physician, and the quality of the images needed to make a diagnosis.
Magnetic Resonance Venography (MRV) and Magnetic Resonance Angiography (MRA)
MRV and MRA examinations are similar to an MRI, but they focus exclusively on the venous and arterial blood vessels in the head and neck area. A strong magnetic field is used to evaluate blood flow patterns and blood vessel abnormalities.
In some cases, dye is injected into the bloodstream to improve the visibility of certain structures. A typical MRA examination and a typical MRV examination take approximately 10 minutes each to complete.