Compatibility of cervical spine braces with MR imaging: a study of nine nonferrous devices.

Several cervical spine braces and orthoses were evaluated for their compatibility with imaging in the MR scanner. Nine such devices were investigated: EXO cervical collar, Philadelphia collar, S.O.M.I. cervical orthosis, Guilford cervical orthosis, modified Guilford cervical orthosis, PMT halo cervical orthosis, modified PMT halo cervical orthosis, Bremer halo system, and Bremer MR-compatible halo system. Devices containing ferrous materials detected by a small bar magnet were not scanned. The remaining devices applied to a volunteer or a patient were scanned to evaluate image quality in the generation of images of the cervical spine and, in some cases, the brain. Orthoses that contained electrically conductive loops produced unsatisfactory scans. Replacement of ferrous materials with nonferrous metals and alloys and elimination of electrical loops proved to be necessary to make cervical braces and orthoses MR-compatible. Cervical orthoses with aluminum or graphite-carbon composite components that are interconnected with plastic joints such as the plastic ball-and-socket joints are, to date, the most successfully designed devices for MR compatibility. To make these orthoses CT compatible, low electron density materials are presently being evaluated to replace the titanium skull pins.