title: PNist: interactive volumetric measurements of plexiform neurofibromas in MRI scans.
abstract: OBJECTIVE
  Volumetric measurements of plexiform neurofibromas (PNs) are time consuming and error prone, as they require the delineation of the PN boundaries, which is mostly impractical in the daily clinical setup. Accurate volumetric measurements are seldom performed for these tumors mainly due to their great dispersion, size and multiple locations. This paper presents a semiautomatic method for segmentation of PN from STIR MRI scans.
  
  
  METHODS
  Plexiform neurofibroma interactive segmentation tool (PNist) is a new tool to segment PNs in STIR MRI scans. The method is based on histogram tumor models computed from a training set.
  
  
  RESULTS
  Experimental results from 28 datasets show an average absolute volume difference of 6.8 % with an average user time of approximately 7 min versus more than 13 min with manual delineation. In complex cases, the PNist user time is less than half in compared to state-of-the-art tools.
  
  
  CONCLUSIONS
  PNist is a new method for the semiautomatic segmentation of PN lesions. Its simplicity and reliability make it unique among other state-of-the-art methods. It has the potential to become a clinical tool that allows the reliable evaluation of PN burden and progression.
authors.affiliation: School of Engineering and Computer Science and The Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University of Jerusalem, Jerusalem, Israel, weizmanl@gmail.com.
authors.forename: Lior
authors.initials: L
authors.lastname: Weizman
authors.forename: Dina
authors.initials: D
authors.lastname: Helfer
authors.forename: Dafna
authors.initials: D
authors.lastname: Ben Bashat
authors.forename: Li-Tal
authors.initials: LT
authors.lastname: Pratt
authors.forename: Leo
authors.initials: L
authors.lastname: Joskowicz
authors.forename: Shlomi
authors.initials: S
authors.lastname: Constantini
authors.forename: Ben
authors.initials: B
authors.lastname: Shofty
authors.forename: Liat
authors.initials: L
authors.lastname: Ben Sira
mesh_terms: D016543:Central Nervous System Neoplasms / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D018318:Neurofibroma, Plexiform / Q000473:pathology*; D015203:Reproducibility of Results; D047368:Tumor Burden