For patients referred for clinical suspicion of peripheral neuropathy in the upper extremities, magnetic resonance neurography (MRN) offers significantly higher sensitivity than high-resolution ultrasound (HRUS), according to new research findings.
In the prospective study, recently published in Radiology, researchers compared HRUS and MRN in 800 patients (mean age of 47.8 years) who were referred for suspected peripheral neuropathy in the upper extremity over a six-year period.
The study authors found that MRN offers significantly higher sensitivity than HRUS for diagnosing upper extremity peripheral neuropathy (91.6 percent vs. 68.7 percent) as well as higher accuracy (85.4 percent vs. 70.6 percent).
“ … Magnetic resonance neurography (MRN) offers excellent soft tissue contrast for both deep and superficial nerves, and additionally provides information about surrounding structures including adjacent muscles. Complex patterns of nerve lesions can be detected easily,” wrote lead study author Olivia Foesleitner, M.D., Ph.D., who is affiliated with the Department of Neuroradiology at Heidelberg University Hospital in Heidelberg, Germany, and colleagues.
“Furthermore, MRN studies are reproducible and tissue properties can be characterized with different sequences and application of intravenous contrast agent.”
In subgroup analysis, the researchers also found that MRN offered over 18 percent higher sensitivity than HRUS or traumatic etiologies of peripheral neuropathy (85.8 percent vs. 67.1 percent), and over 20 percent higher sensitivity for peripheral neuropathy derived from inflammatory etiologies (97.5 percent vs. 77.3 percent) and compression etiologies (95.6 percent vs. 75.2 percent).
Three Key Takeaways
1. Higher sensitivity and accuracy of MRN. Magnetic resonance neurography (MRN) demonstrated significantly higher sensitivity (91.6 percent vs. 68.7 percent) and accuracy (85.4 percent vs. 70.6 percent) compared to high-resolution ultrasound (HRUS) in diagnosing upper extremity peripheral neuropathy.
2. Better sensitivity of MRN across multiple etiologies of peripheral neuropathies. MRN provides excellent soft tissue contrast, allowing for better visualization of both deep and superficial nerves, surrounding structures, and complex nerve lesions. It showed particularly higher sensitivity for traumatic (85.8 percent vs. 67.1 percent), inflammatory (97.5 percent vs. 77.3 percent), and compression (95.6 percent vs. 75.2 percent) neuropathies.
3. HRUS as a cost-effective alternative with higher specificity. While MRN offers superior sensitivity, HRUS demonstrated nearly 10 percent higher specificity (76 percent vs. 66.2 percent) and remains a valuable, cost-effective, and dynamic imaging modality, especially for superficially located nerves.
However, researchers emphasized judicious use of MRN in light of its time-intensive nature and higher costs. They also pointed out that HRUS demonstrated nearly 10 percent higher specificity overall than MRN (76 percent vs. 66.2 percent).
“High-resolution imaging methods have entered the field revealing essential complementary information about peripheral neuropathies, including morphology, location, and relationship to surrounding tissue. High-resolution nerve ultrasound (HRUS) is an inexpensive and dynamic modality with high spatial resolution, especially for superficially located nerves,” added Foesleitner and colleagues.
(Editor’s note: For related content, see “Philips Receives FDA Clearance for Ultrasound-Guided Needle Tracking,”“Multicenter Study Validates New MRI Scoring System for Peripheral Neuropathy” and “Can Ultrasound-Guided Hydrodissection be a Viable Alternative for Carpal Tunnel Syndrome?”)
In regard to study limitations, the authors acknowledged the results, drawn from a single academic facility, may not be applicable to broader populations. They also conceded that access to MRN and HRUS may be limited in different parts of the world. The researchers also conceded possible bias affecting the results with HRUS consistently preceding the use of MRN.
