Peripheral Nerve Imaging

Despite the tremendous advances in cross-sectional imaging modalities from the 1980’s to the present, peripheral nerves have often been ignored as unimportant or too small to be reliably seen. However today, ultrasound and magnetic resonance imaging scanners allow high quality depictions of peripheral nerves and the many disorders that may be encountered. While high frequency ultrasound is very useful in the analysis of some peripheral nerves, magnetic resonance nerve imaging has emerged into a more comprehensive and dedicated examination, often referred to as magnetic resonance neurography (MR neurography or MRN) [1]. This term was introduced by Filler and Howe et al. and includes high-resolution morphologic imaging of the peripheral nerves as well as functional imaging based on diffusion weighted imaging (DWI) and diffusion tensor imaging (DTI) [2, 3]. The concept of magnetic resonance neurography is somewhat like magnetic resonance angiography where the visualization of the vascular system is enhanced by suppressing the signal from the surrounding soft tissue. Similarly, the signal from the surrounding tissue is may be suppressed in magnetic resonance neurography for better visualization of small peripheral nerves. Advances in pulse sequences for magnetic resonance neurography are being increasingly adopted by scanner manufacturers for dedicated magnetic resonance neurography.