title: Magnetic resonance imaging of canine mast cell tumors.
abstract: Mast cell tumors (MCT) are the most common cutaneous tumors in dogs. Our purpose was to describe the magnetic resonance (MR) imaging characteristics of cutaneous MCT and to identify imaging characteristics that allow differentiation of metastatic from normal lymph nodes. Eight dogs with a total of nineMCT were imaged as were their presumed draining and associated contralateral lymph nodes. The signal intensity of tumors and lymph nodes was compared to adjacent musculature. On T2-W images, 7/9 MCT were hyperintense to muscle and 2/9 were isointense. On T1-W images, 8/9 MCT were isointense and 1/9 were mildly hypointense. All tumors were strongly contrast enhancing; 5/9 were homogeneous and 4/9 heterogeneous in their enhancement patterns. Six lymph node pairs were included in the evaluation (five sentinel lymph nodes with metastases, one without, and six contralateral lymph nodes). Metastatic lymph nodes were significantly larger than their contralateral lymph nodes (P = 0.039). All lymph nodes were isointense on T1-W images and hyperintense on T2-W images. 5/5 metastatic and 2/7 normal lymph nodes were heterogeneously T2-hyperintense. All lymph nodes were moderately to strongly contrast enhancing. 4/5 metastatic and 2/7 normal lymph nodes had heterogeneous enhancement patterns. While heterogeneity was more common in metastatic than in normal lymph nodes, this difference was not significant (P = 0.058 for T2-W images; P = 0.234 for postcontrast images). MR imaging may be useful in the presurgical evaluation and clinical staging of cutaneous MCT.
authors.affiliation: Department of Small Animal Clinical Sciences, C247 Veterinary Medical Center, University of Tennessee College of Veterinary Medicine, Knoxville, TN 37996-4544, USA.
authors.forename: Esteban
authors.initials: E
authors.lastname: Pokorny
authors.forename: Silke
authors.initials: S
authors.lastname: Hecht
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Sura
authors.forename: Amy K
authors.initials: AK
authors.lastname: LeBlanc
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Phillips
authors.forename: Gordon A
authors.initials: GA
authors.lastname: Conklin
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Haifley
authors.forename: Kim
authors.initials: K
authors.lastname: Newkirk
mesh_terms: D000818:Animals; D004283:Dog Diseases / Q000175:diagnosis*; D004285:Dogs; D008207:Lymphatic Metastasis; D008279:Magnetic Resonance Imaging / Q000662:veterinary*; D012515:Mast-Cell Sarcoma / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D012878:Skin Neoplasms / Q000175:diagnosis / Q000662:veterinary*