Advanced imaging technologies play a vital role in the diagnosis and treatment of patients with spinal problems. The most widely used advanced imaging technology is magnetic resonance imaging, or MRI. Like any imaging option, the MRI has certain strengths and weaknesses. Understanding the basics of how an MRI works allows a healthcare provider to intelligently decide whether or not it is the most appropriate test for a particular condition or complaint.
The human body has many elements and one of the most plentiful is hydrogen, which has a nucleus with an odd number of protons and neutrons. Researchers theorized that placing a human body in a magnetic field would cause the charged hydrogen atoms to “align” along the magnetic field. These same atoms can be temporarily “energized” when bombarded with radio waves. When the radio wave pulse is discontinued, the energy is released.
In the human body, different tissues have different numbers of hydrogen atoms that release energy at different rates and amounts. An MRI is a complex array of magnets and radio wave coils that magnetize and send radio wave pulses through the human body at programmable strengths, rates and pulse lengths.
There are two basic pulse sequences, T1 and T2. T1 pictures are often referred to as “fat images” because they better depict adipose tissue. T2 pictures are termed “water images” because tissues with greater fluid content are better visualized. Conditions with higher water content such as edema, tumors and infections are, in most cases, better visualized on T2 images.
In order to “light up” the hydrogen atoms surrounding abnormal or damaged tissue for better MRI visualization, technicians use gadolinium, a noniodinated contrast that decreases T1 relaxation time. When tumor or infection is suspected or when there has been previous surgery in the region under study, gadolinium should be requested to increase the diagnostic yield of the MRI.
In the evaluation and treatment of spine-related disorders, an MRI is usually used to visualize disc pathology such as a ruptured disc and annular tears. In addition, the spinal cord, marrow, soft tissues/muscles, scar tissue and most tumors and infection are best visualized with MRI.
Due to the relatively low hydrogen content of bone, osseous structures do not show up as well with MRI. CT scanning is considered the best imaging technology for assessment of bony abnormalities, the neuroforamen, and some foraminal disc herniations. CT scanning in the cervical spine allows optimal visualization of the neuroforamen but must be performed with intravenous contrast to distinguish pathology from nearby vasculature.
At Natural Pain Solutions, we are committed to reviewing and interpreting complex imaging studies with our patients. Please call us to discuss the most appropriate imaging choices available today.
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