title: MR-compatible assistance system for biopsy in a high-field-strength system: initial results in patients with suspicious prostate lesions.
abstract: OBJECTIVE
  To examine the feasibility and safety of magnetic resonance (MR)-guided biopsy by using a transgluteal approach in patients with suspicious prostate lesions by using an MR-compatible robotic system and a 1.5-T MR system.
  
  
  METHODS
  The study was approved by the institutional review board of University Frankfurt, and informed consent was obtained from each patient. A total of 20 patients (age range, 57.8-71.9 years; mean age, 65.1 years) underwent biopsy in a closed-bore high-field-strength MR system. Biopsy was performed with an MR-compatible pneumatically driven robotic system. T1-weighted gradient-echo fast low-angle shot and T2-weighted true fast imaging with steady-state precession sequences were used to plan and guide the intervention with a transgluteal access on the external planning computer of the assistance system. The system calculated the trajectory and then moved the guiding arm to the insertion point. The cannula was advanced manually, and biopsies were performed with the coaxial technique by using a 15-gauge pencil tip needle. Intervention time, complications, and biopsy findings were documented.
  
  
  RESULTS
  The MR-compatible robotic system did not interfere with image quality, nor did MR imaging cause dysfunction of the robot. In one patient, the interventionist caused a fail-safe system shutdown. This was due to inadvertent displacement of the guiding arm during cannula insertion. This problem was solved by increasing the displacement threshold. Accurate coaxial cannula biopsy could be performed in all subsequent patients. Sufficient histopathologic assessment was performed in 19 patients. Insufficient material was retrieved in the patient who experienced fail-safe system shutdown. The median intervention time was 39 minutes (23-65 minutes). No procedure-related complications were observed.
  
  
  CONCLUSIONS
  Preliminary results indicate that MR-guided robot-assisted biopsy is feasible and can be performed safely with highly accurate cannula placement.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Johann Wolfgang Goethe-University, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany. Zangos@em.uni-frankfurt.de
authors.forename: Stephan
authors.initials: S
authors.lastname: Zangos
authors.forename: Andreas
authors.initials: A
authors.lastname: Melzer
authors.forename: Katrin
authors.initials: K
authors.lastname: Eichler
authors.forename: Cyrus
authors.initials: C
authors.lastname: Sadighi
authors.forename: Axel
authors.initials: A
authors.lastname: Thalhammer
authors.forename: Boris
authors.initials: B
authors.lastname: Bodelle
authors.forename: Renate
authors.initials: R
authors.lastname: Wolf
authors.forename: Tatjana
authors.initials: T
authors.lastname: Gruber-Rouh
authors.forename: Dirk
authors.initials: D
authors.lastname: Proschek
authors.forename: Renate
authors.initials: R
authors.lastname: Hammerstingl
authors.forename: Cindy
authors.initials: C
authors.lastname: Müller
authors.forename: Martin G
authors.initials: MG
authors.lastname: Mack
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Vogl
mesh_terms: D000368:Aged; D016477:Artifacts; D001707:Biopsy, Needle / Q000295:instrumentation*; D005240:Feasibility Studies; D006801:Humans; D053783:Magnetic Resonance Imaging, Interventional / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D016684:Prone Position; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000473:pathology; D012371:Robotics / Q000295:instrumentation*; D012449:Safety; D012984:Software