Of preference, a magnetic resonance imaging (MRI) of the lumbosacral spine with contrast is ideal, more precise and less injurious. The MRI uses a magnetic field and radio waves to produce cross-sectional images of particular organs and bodily tissues. To obtain the best results is imperative that an intravenous dye is administered only a few minutes before the test in order to be able to have the optimal images, especially within the dural sac, ideally obtaining axial and saggital views of the lumbosacral region. However, the presence of certain non-titanium metal objects (screws, wires, etc.) makes the MRI contraindicated since it may heat certain metals. If an MRI is contraindicated, the diagnosis of arachnoiditis will have to be made using a computed tomography (CT) scan, which requires the administration of contrast media into the intrathecal compartment; however the images are not as informative as those obtained from an MRI. The intrathecal injection of a dye (myelogram) presents one more obstacle, as it may be hazardous, especially in cases of infections. An intrathecal injection refers to injecting a substance directly into the cerebrospinal fluid that surrounds the brain and spinal cord.
The full evidence report prepared by ECRI is available from the Agency for Healthcare Research and Quality. Printed copies may be obtained free of charge from the AHRQ Publications Clearinghouse by calling 1-800-358-9295 and asking for Evidence Report/Technology Assessment No. 32, Treatment of Degenerative Lumbar Spinal Stenosis (AHRQ Publication No. 01-E048). Internet users can access the report online through AHRQ’s Web site at http:// . ECRI is a nonprofit health services research agency and a Collaborating Center for Healthcare Technology Assessment of the World Health Organization.