title: Changes in cyst volume following intraoperative MRI-guided Ommaya reservoir placement for cystic craniopharyngioma.
abstract: BACKGROUND
  Intracavitary treatment of solitary cystic craniopharyngiomas with (32)P is an emerging treatment option, especially for pediatric patients. We have treated two patients with solitary cystic craniopharyngiomas using intraoperative MRI (iMRI)-guided catheter placement.
  
  
  METHODS
  The optical tracking system of the General Electric Signa SP iMRI system was utilized for preoperative planning and intraoperative catheter tracking during insertion. Intraoperative volumetric imaging was then used to confirm final catheter position. Patients were brought back to the iMRI suite approximately 8 weeks later and diluted gadolinium was injected with further MRI to confirm the absence of communication between the cyst lumen and surrounding CSF spaces and for volumetric analysis.
  
  
  RESULTS
  Intraoperative imaging illustrated deformation and changes in the cyst wall during catheter placement and cyst aspiration and confirmed final catheter placement. Images acquired 8 weeks following catheter placement prior to the instillation of (32)P showed decreases in cyst volume of 40 and 85%.
  
  
  CONCLUSIONS
  iMRI-guided catheter placement for cystic craniopharyngiomas helps to assure successful catheter placement. Significant decreases in cyst volume occur in the interval between catheter placement and (32)P administration and must be accounted for to prevent overdosing of the radioisotope.
authors.affiliation: Department of Neurological Surgery, University of Louisville School of Medicine and Norton Healthcare Intraoperative MRI Center, Louisville, Ky., USA.
authors.forename: T W
authors.initials: TW
authors.lastname: Vitaz
authors.forename: S
authors.initials: S
authors.lastname: Hushek
authors.forename: C B
authors.initials: CB
authors.lastname: Shields
authors.forename: T
authors.initials: T
authors.lastname: Moriarty
mesh_terms: D000293:Adolescent; D001918:Brachytherapy / Q000295:instrumentation*; D002408:Catheters, Indwelling; D002675:Child, Preschool; D003131:Combined Modality Therapy; D003397:Craniopharyngioma / Q000532:radiotherapy* / Q000601:surgery; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008297:Male; D010761:Phosphorus Radioisotopes / Q000627:therapeutic use; D010911:Pituitary Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D018714:Radiotherapy, Adjuvant; D013238:Stereotaxic Techniques / Q000295:instrumentation*; D013396:Suction / Q000295:instrumentation; D025321:Surgery, Computer-Assisted / Q000295:instrumentation*
chemical_list: D010761:Phosphorus Radioisotopes