title: Automatic Segmentation of the Eye in 3D Magnetic Resonance Imaging: A Novel Statistical Shape Model for Treatment Planning of Retinoblastoma.
abstract: OBJECTIVE
  Proper delineation of ocular anatomy in 3-dimensional (3D) imaging is a big challenge, particularly when developing treatment plans for ocular diseases. Magnetic resonance imaging (MRI) is presently used in clinical practice for diagnosis confirmation and treatment planning for treatment of retinoblastoma in infants, where it serves as a source of information, complementary to the fundus or ultrasonographic imaging. Here we present a framework to fully automatically segment the eye anatomy for MRI based on 3D active shape models (ASM), and we validate the results and present a proof of concept to automatically segment pathological eyes.
  
  
  METHODS
  Manual and automatic segmentation were performed in 24 images of healthy children's eyes (3.29 ± 2.15 years of age). Imaging was performed using a 3-T MRI scanner. The ASM consists of the lens, the vitreous humor, the sclera, and the cornea. The model was fitted by first automatically detecting the position of the eye center, the lens, and the optic nerve, and then aligning the model and fitting it to the patient. We validated our segmentation method by using a leave-one-out cross-validation. The segmentation results were evaluated by measuring the overlap, using the Dice similarity coefficient (DSC) and the mean distance error.
  
  
  RESULTS
  We obtained a DSC of 94.90 ± 2.12% for the sclera and the cornea, 94.72 ± 1.89% for the vitreous humor, and 85.16 ± 4.91% for the lens. The mean distance error was 0.26 ± 0.09 mm. The entire process took 14 seconds on average per eye.
  
  
  CONCLUSIONS
  We provide a reliable and accurate tool that enables clinicians to automatically segment the sclera, the cornea, the vitreous humor, and the lens, using MRI. We additionally present a proof of concept for fully automatically segmenting eye pathology. This tool reduces the time needed for eye shape delineation and thus can help clinicians when planning eye treatment and confirming the extent of the tumor.
authors.affiliation: Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland; Ophthalmic Technology Group, ARTORG Center of the University of Bern, Bern, Switzerland; Centre d'Imagerie BioMédicale, University of Lausanne, Lausanne, Switzerland. Electronic address: carlos.cillerruiz@unil.ch.
authors.forename: Carlos
authors.initials: C
authors.lastname: Ciller
authors.affiliation: Ophthalmic Technology Group, ARTORG Center of the University of Bern, Bern, Switzerland; Department of Ophthalmology, Inselspital, Bern University Hospital, Bern, Switzerland.
authors.forename: Sandro I
authors.initials: SI
authors.lastname: De Zanet
authors.affiliation: Ophthalmic Technology Group, ARTORG Center of the University of Bern, Bern, Switzerland; Department of Ophthalmology, Inselspital, Bern University Hospital, Bern, Switzerland.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Rüegsegger
authors.affiliation: Department of Radiation Oncology, Inselspital, Bern University Hospital, Bern, Switzerland.
authors.forename: Alessia
authors.initials: A
authors.lastname: Pica
authors.affiliation: Ophthalmic Technology Group, ARTORG Center of the University of Bern, Bern, Switzerland; Department of Ophthalmology, Inselspital, Bern University Hospital, Bern, Switzerland.
authors.forename: Raphael
authors.initials: R
authors.lastname: Sznitman
authors.affiliation: Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland; Signal Processing Laboratory, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Thiran
authors.affiliation: Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland.
authors.forename: Philippe
authors.initials: P
authors.lastname: Maeder
authors.affiliation: Unit of Pediatric Ocular Oncology, Jules Gonin Eye Hospital, Lausanne, Switzerland.
authors.forename: Francis L
authors.initials: FL
authors.lastname: Munier
authors.affiliation: Ophthalmic Technology Group, ARTORG Center of the University of Bern, Bern, Switzerland; Department of Ophthalmology, Inselspital, Bern University Hospital, Bern, Switzerland.
authors.forename: Jens H
authors.initials: JH
authors.lastname: Kowal
authors.affiliation: Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland; Centre d'Imagerie BioMédicale, University of Lausanne, Lausanne, Switzerland; Signal Processing Laboratory, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
authors.forename: Meritxell Bach
authors.initials: MB
authors.lastname: Cuadra
mesh_terms: D059925:Anatomic Landmarks / Q000033:anatomy & histology*; D002648:Child; D002675:Child, Preschool; D003315:Cornea / Q000033:anatomy & histology; D005123:Eye / Q000033:anatomy & histology*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007223:Infant; D007908:Lens, Crystalline / Q000033:anatomy & histology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009898:Optic Disk / Q000033:anatomy & histology; D011880:Radiotherapy Planning, Computer-Assisted; D019572:Retinal Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D012175:Retinoblastoma / Q000473:pathology / Q000532:radiotherapy*; D012590:Sclera / Q000033:anatomy & histology; D014822:Vitreous Body / Q000033:anatomy & histology