title: How to operate a liver tumor you cannot see.
abstract: BACKGROUND
  As recent chemotherapy regimens for metastatic colorectal cancer become more and more effective in a neoadjuvant setting before liver surgery, a "complete" clinical response is sometimes documented on imaging. Without operation though, metastatic recurrence is likely to commence within 12 months. Surgeons now face the problem to resect non-visualizable and non-palpable lesions.
  
  
  METHODS
  Computer-based virtual surgery planning can be used to fuse pre- and postchemotherapy computed tomography data to develop an operative strategy. This information is then intraoperatively transferred to the liver surface using an image-guided stereotactically navigated ultrasound dissector. This enables the surgeon to perform a resection that is otherwise not possible.
  
  
  RESULTS
  During operation, detection of the lesion through palpation or ultrasound was impossible. After registering the virtual operation plan into the navigation system, the planned resection was performed without problems. Histopathologic workup showed vital tumor cells in the specimen.
  
  
  CONCLUSIONS
  The new image-guided stereotactic navigation technique combined with virtual surgery planning can solve the surgeon's dilemma and yield a successful operation.
authors.affiliation: Department of General and Visceral Surgery, Celle General Hospital, Siemensplatz 4, 29223, Celle, Germany. oldhafer@liversurgery.de
authors.forename: Karl J
authors.initials: KJ
authors.lastname: Oldhafer
authors.forename: Gregor A
authors.initials: GA
authors.lastname: Stavrou
authors.forename: Guido
authors.initials: G
authors.lastname: Prause
authors.forename: Heinz-Otto
authors.initials: HO
authors.lastname: Peitgen
authors.forename: Tim C
authors.initials: TC
authors.lastname: Lueth
authors.forename: Stefan
authors.initials: S
authors.lastname: Weber
mesh_terms: D015179:Colorectal Neoplasms / Q000473:pathology; D016287:Computer Peripherals; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D055096:Optical Devices; D018570:Risk Assessment; D013238:Stereotaxic Techniques; D025321:Surgery, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography