title: Direct application of MR images to computer-assisted bone tumor surgery.
abstract: BACKGROUND
  We describe a method for the direct application of MR images to navigation-assisted bone tumor surgery as an alternative to CT-MRI fusion.
  
  
  METHODS
  Six patients with an orthopedic malignancy were employed for this method during navigation-assisted tumor resection. Tumor types included osteosarcoma (4), high-grade chondrosarcoma (1), and adamantinoma (1). Mean patient age was 25.3 years (range 18-52 years). Mean duration of follow-up was 25.8 months (range 18-32 months). Resorbable pin placement and rapid 3-dimensional spoiled gradient echo sequences made the direct application of MR images to computer-assisted bone tumor surgery without CT-MR image fusion possible. A paired-point registration technique was employed for patient-image registration in all patients.
  
  
  RESULTS
  It took 20 min on average to set up the navigation (range 15-25 min). The mean registration error was 0.98 mm (range 0.4-1.7 mm). On histologic examination, distances from tumors to resection margins were in accord with preoperative plans. No patient had a local recurrence or distant metastasis at the last follow-up.
  
  
  CONCLUSIONS
  Direct patient-to-MRI registration is a very useful method for bone tumor surgery, permitting the application of MR images to intraoperative visualization without any additional costs or exposure of the patient to radiation from the preoperative CT scan.
authors.affiliation: Department of Orthopedic Surgery, Kyungpook National University College of Medicine, Daegu, Korea. mdchs111@snu.ac.kr
authors.forename: Hwan Seong
authors.initials: HS
authors.lastname: Cho
authors.forename: Il-Hyung
authors.initials: IH
authors.lastname: Park
authors.forename: In-Ho
authors.initials: IH
authors.lastname: Jeon
authors.forename: Young-Gun
authors.initials: YG
authors.lastname: Kim
authors.forename: Ilkyu
authors.initials: I
authors.lastname: Han
authors.forename: Han-Soo
authors.initials: HS
authors.lastname: Kim
mesh_terms: D050398:Adamantinoma / Q000175:diagnosis / Q000601:surgery; D000293:Adolescent; D000328:Adult; D001858:Bone Nails; D001859:Bone Neoplasms / Q000175:diagnosis* / Q000601:surgery; D002813:Chondrosarcoma / Q000175:diagnosis / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D019637:Orthopedic Procedures / Q000295:instrumentation*; D012516:Osteosarcoma / Q000175:diagnosis / Q000601:surgery; D015203:Reproducibility of Results; D012189:Retrospective Studies; D025321:Surgery, Computer-Assisted / Q000379:methods*; D055815:Young Adult