title: Heads-up intraoperative endoscopic imaging: a prospective evaluation of techniques and limitations.
abstract: OBJECTIVE
  Endoscopes have been used adjunctively for spinal and cranial microsurgical procedures and directly for ventricular exploration, fenestration, and catheterization. Technological advances now allow for multi-imaging technologies, including a so-called "heads-up display," allowing the surgeon to view the operative field and the endoscopic image simultaneously.
  
  
  METHODS
  A high-resolution, active matrix liquid crystal display is built into the frame of the eyewear, with a display density of 182,000 pixels (280 x 650 pixels) and a resolution of 200 lines. The display occupies approximately 20% of the visual field. The headgear weighs 4 oz, with dimensions of 9 x 18 x 17 cm. The modular interface weighs 7 oz. Two different visualization systems can be used. The first uses a single integrated interface (IM 300), whereas the second (remote 900) is a 900-MHz frequency modulation wireless system that provides for a line-of-sight link between the NTSC source and the modular interface (range = 100 ft).
  
  
  RESULTS
  Heads-up adjunctive endoscopy was used in 60 patients during 18 months. The procedures included 16 craniotomies, 1 intradural lumbar biopsy, and 42 ventriculoperitoneal shunt placements. Follow-up was obtained at a minimum of 1 year. Patient age ranged from 1 month to 58 years. The only complication was a transient loss of auditory evoked potentials after contact of the eighth nerve by the endoscope.
  
  
  CONCLUSIONS
  We describe a portable, light-weight heads-up display imaging system, which we have used in 60 operative procedures. Benefits of the heads-up system include portability and a high-resolution digital monocular image, which reduces eye strain and vertigo. The ideal headgear will likely be an extremely high-resolution liquid crystal display-based or cathode ray tube-based semi-immersive system, with all of the benefits currently described for two-dimensional heads-up systems (i.e., light weight, portability, image quality, and the avoidance of complications associated with immersive systems).
authors.affiliation: Division of Neurological Surgery, Children's Hospital Los Angeles, University of Southern California, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: Levy
authors.forename: J D
authors.initials: JD
authors.lastname: Day
authors.forename: F
authors.initials: F
authors.lastname: Albuquerque
authors.forename: G
authors.initials: G
authors.lastname: Schumaker
authors.forename: S L
authors.initials: SL
authors.lastname: Giannotta
authors.forename: J G
authors.initials: JG
authors.lastname: McComb
mesh_terms: D000293:Adolescent; D000328:Adult; D001706:Biopsy / Q000295:instrumentation*; D001921:Brain / Q000473:pathology* / Q000601:surgery; D002648:Child; D002675:Child, Preschool; D003399:Craniotomy / Q000295:instrumentation; D019723:Endoscopes; D004867:Equipment Design; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008866:Microsurgery / Q000295:instrumentation*; D008875:Middle Aged; D013116:Spinal Cord / Q000473:pathology* / Q000601:surgery; D014584:User-Computer Interface; D017287:Ventriculoperitoneal Shunt / Q000295:instrumentation; D014741:Video Recording / Q000295:instrumentation*