title: Smartphone-assisted guide for the placement of ventricular catheters.
abstract: OBJECTIVE
  Freehand placement of ventricular catheters (VC) is reported to be inaccurate in 10-40 %. Endoscopy, ultrasound, or neuronavigation are used in selected cases with significant technical and time-consuming efforts. We suggest a smartphone-assisted guiding tool for the placement of VC.
  
  
  METHODS
  Measurements of relevant parameters in 3D-MRI datasets in a patient cohort with narrow ventricles for a frontal precoronal VC placement were performed. In this context, a guiding tool was developed to apply the respective measures for VC placement. The guiding tool was tested in a phantom followed by CT imaging to quantify placement precision. A smartphone application was designed to assist the relevant measurements. The guide was applied in 35 patients for VC placement.
  
  
  RESULTS
  MRI measurements revealed the rectangular approach in the sagittal plane and the individual angle towards the tangent in the coronal section as relevant parameter for a frontal approach. The latter angle ranged from medial (91.96° ± 2.75°) to lateral margins (99.56° ± 4.14°) of the ventricle, which was similar in laterally shifted (±5 mm) entry points. The subsequently developed guiding tool revealed precision measurements in an agarose model with 1.1° ± 0.7° angle deviation. Using the smartphone-assisted guide in patients with narrow ventricles (frontal occipital horn ratio, 0.38 ± 0.05), a primary puncture of the ventricles was possible in all cases. No VC failure was observed during follow-up (9.1 ± 5.3 months).
  
  
  CONCLUSIONS
  VC placement in narrow ventricles requires accurate placement with simple means in an every-case routine. The suggested smartphone-assisted guide meets these criteria. Further data are planned to be collected in a prospective randomized study.
authors.affiliation: Pediatric Neurosurgery, Campus Virchow Klinikum, Charité Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany. uthomale@charite.de
authors.forename: U W
authors.initials: UW
authors.lastname: Thomale
authors.forename: T
authors.initials: T
authors.lastname: Knitter
authors.forename: A
authors.initials: A
authors.lastname: Schaumann
authors.forename: S A
authors.initials: SA
authors.lastname: Ahmadi
authors.forename: P
authors.initials: P
authors.lastname: Ziegler
authors.forename: M
authors.initials: M
authors.lastname: Schulz
authors.forename: C
authors.initials: C
authors.lastname: Miethke
mesh_terms: D000293:Adolescent; D000328:Adult; D002408:Catheters, Indwelling; D002557:Cerebrospinal Fluid Shunts / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006849:Hydrocephalus / Q000601:surgery*; D021621:Imaging, Three-Dimensional; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018709:Statistics, Nonparametric; D017216:Telemedicine / Q000295:instrumentation* / Q000379:methods*; D055815:Young Adult