title: The value of radiographic screening for metallic particles in the equine foot and size of related artifacts on low-field MRI.
abstract: Magnetic susceptibility artifacts as a result of metal debris from shoeing are a common problem in magnetic resonance imaging of the equine foot. Our purpose was to determine the suitability of radiography as a screening tool for the presence and location of metallic particles in the equine foot and to predict the size of the resultant magnetic susceptibility artifact. Radiography had 100% sensitivity for detection of metal particles > or = 1 mm diameter. Metal particles of known diameter were placed within the hoof wall of 22 cadaver feet and scanned with a low-field strength MR imaging unit (0.21 T). Magnetic resonance images were characterized by a signal void with a hyperintense rim and adjacent image distortion at the level of the known metal location. T2* weighted sequences were the most and fast spin echo (FSE) sequences the least affected. For all four sequences (T1 gradient echo [GRE]; T2*W GRE; T2 FSE; and short tau inversion recovery FSE), linear relationships were observed between particle and resultant artifact size. Magnetic susceptibility artifact size, location and superimposition on clinically relevant anatomic structures can be predicted radiographically for particles larger than 1 mm. If metal debris cannot be removed, the least artifact-prone FSE sequences should be selected.
authors.affiliation: Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Roslin EH25 9RG, UK. carolina.urraca@ed.ac.uk
authors.forename: Carolina I
authors.initials: CI
authors.lastname: Urraca del Junco
authors.forename: Darren J
authors.initials: DJ
authors.lastname: Shaw
authors.forename: Martin P
authors.initials: MP
authors.lastname: Weaver
authors.forename: Tobias
authors.initials: T
authors.lastname: Schwarz
mesh_terms: D000818:Animals; D016477:Artifacts; D005528:Foot / Q000000981:diagnostic imaging*; D006736:Horses; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000662:veterinary; D008670:Metals; D011859:Radiography; D012680:Sensitivity and Specificity; D013193:Stainless Steel; D015898:Tomography Scanners, X-Ray Computed / Q000662:veterinary*
chemical_list: D008670:Metals; D013193:Stainless Steel