Until recently, precisely localizing the site(s) of peripheral nerve damage was difficult, which made it challenging for doctors to accurately diagnose and treat peripheral nerve disorders. At HSS, we have optimized a specialized MRI technique called magnetic resonance (MR) neurography to localize abnormalities of nerves from the skull base to the tip of the toes.
Patients with a wide range of conditions that affect the nerves can now be more quickly and accurately diagnosed.
MR neurography, also known as peripheral nerve MRI, uses high-resolution techniques to visualize nerves throughout the body. A radiologist who specializes in nerve imaging reviews the images to detect abnormal features of the nerve that may indicate injury or inflammation, such as increased brightness or size. By localizing and characterizing nerve abnormalities, MR neurography aids in the diagnosis and management of various conditions.
Specially trained HSS radiologists work closely with referring physicians to determine the appropriate imaging exams for diagnosis and treatment planning.
Conventional MRIs can sometimes show nerve abnormalities, but MR neurography imaging is more sensitive, since it is specially tailored to image nerves. MR neurography uses advanced techniques to depict small nerves that may not be visualized on standard MRI exams. MR neurography is often used in conjunction with other examinations, including a physical exam, ultrasound, and electrodiagnostic testing, which includes electromyography (EMG).
MR neurography also provides visual clues about whether the muscles that an injured nerve supplies have atrophied or lost function as a result of the nerve damage.
MR neurography can be performed on almost anyone with a suspected nerve injury. Symptoms of nerve damage may include pain, numbness, tingling, and muscle weakness. MR neurography can be performed as early as several hours or days following nerve injury. This has an advantage over electrodiagnostic studies, and in particular, electromyography (EMG), which usually requires at least a two- to three-week waiting period before being sensitive to damage. MR neurography can be used to diagnose many traumatic and atraumatic conditions that cause nerve compression, entrapment, or disruption:
In many respects, MR neurography works similarly to standard MRI. It uses strong magnetic fields and radio waves to generate images. The thinly sliced, high-resolution images are designed specifically to enhance the appearance of nerves and muscle, rather than the bones, ligaments, and tendons depicted by more conventional musculoskeletal imaging. Specialized “pulse sequences” can be applied to improve nerve visualization. For example, reducing the signal (brightness) of nearby blood vessels (“vascular suppression”) or fat (“fat suppression”) enhances the appearance of the nerves.
Multiple sequences are usually required to evaluate a single region of the body. A set of pulse sequences grouped together is called the “imaging protocol.”
At HSS, all MR neurography exams are protocoled by an attending radiologist prior to the exam and monitored in real-time, in coordination with the performing technologist, to adjust the protocol as needed.
Some MR neurography exams use intravenous (IV) contrast to evaluate abnormalities or help differentiate nerves from surrounding structures. The contrast agent used in MR neurography exams is the same gadolinium-based contrast agent that is used for conventional MRI. Alternative contrast agents being investigated in our Magnetic Resonance Imaging Lab at Hospital for Special Surgery are sometimes given to patients who choose to participate in our ongoing research.
The duration of an MR neurography exam varies with the area being imaged and other factors. Generally, a single exam lasts 45 to 60 minutes, but may be longer or shorter depending on individual circumstances.
Preparing for an MR neurography exam is the same as preparing for a conventional MRI. There are no food or drink restrictions. You may take your medications as usual unless instructed otherwise.
MR neurography is a very safe and well-tolerated exam. Like MRI, MR neurography does not involve the use of ionizing radiation as do traditional X-rays or CT scans.
Patients will not experience any pain, but those with claustrophobia or aversion to loud noises may speak with their doctor ahead of time about possible modifications as well as with the technologist at the time of examination.
Patients with hip, knee, shoulder or other joint replacements can usually undergo MR neurography. Patients who have certain medical devices or prostheses may not be able to have this type of imaging, or the procedure may need to be modified. Please let our team know if you have any metallic or electronic implants in your body.
The radiologist will generate a written report, which will be made available to your referring physician within 24 to 48 hours of the exam. A copy of your report can be obtained through your MyHSS account typically within 24 hours of exam completion.
If your physician is at HSS, the images will be available immediately following the exam. Your physician will review the MR neurography test results with you and can correlate imaging results with clinical findings.
If your physician is an outside referring provider, a copy of your report will be faxed or mailed, free of charge, to that office. A disc containing the images will also be sent via FedEx. Physicians not on staff at HSS can request Portal Account access to images and reports associated with patients referred to HSS for imaging services. Additional copies of the images can also be obtained on a CD by contacting the file room at 212.606.1135.
Our Magnetic Resonance Imaging (MRI) Lab is constantly working to improve techniques in MR neurography to diagnose and help manage an even wider range of clinical conditions. Current areas of investigation include: