Metal Artifact Reduction Sequence MRN

Evaluation of the Lumbosacral Plexus in Patients with Metallic Implants1

Shivani Ahlawat, M.D.; Jan Fritz, M.D., P.D., D.A.B.R.
Johns Hopkins University School of Medicine, Baltimore, MD, USA

Magnetic resonance neurography (MRN) is a reliable and accurate modality in the assessment of patients with peripheral neuropathy, which can be useful for distinguishing intrinsic and extrinsic etiologies of neuropathy
following surgery. However, MRN surrounding metal implants1 can be challenging to both perform and interpret. The diagnosis of abnormal peripheral nerves often heavily relies on fluid sensitive MR pulse sequences,
but the presence of metal in the field of view introduces image artifacts, distortion and interferes with fat suppression. Conventional turbo spin echo pulse sequences with optimization for metal artifact reduction are best suited for nerve imaging as advanced multispectral, and multi-spatial pulse sequences introduce a degree of blur that obscured nerve details. As such, metal artifact reduction sequence (MARS) techniques can be applied to improve the image quality of MRN in patients with pelvic metallic implants, when compared with standard fast spin echo sequences. We share and describe a high-resolution MARS MRN protocol that yields high image quality and validated diagnostic accuracy for the assessment of lumbosacral neuropathies in patients with metallic implants of the pelvis and hips.

1The MRI restrictions (if any) of the metal implant must be considered prior to patient undergoing MRI exam. MR imaging of patients with metallic implants brings specific risks. However, certain implants are approved by the governing regulatory bodies to be MR conditionally safe. For such implants, the previously mentioned warning may not be applicable. Please contact the implant manufacturer for the specific conditional information. The conditions for MR safety are the responsibility of the implant manufacturer, not of Siemens.