title: Nerve Fascicles and Epineurium Volume Segmentation of Peripheral Nerve Using Magnetic Resonance Micro-neurography.
abstract: The aims of this study were to propose a semiautomated technique to segment and measure the volume of different nerve components of the tibial nerve, such as the nerve fascicles and the epineurium, based on magnetic resonance microneurography and a segmentation tool derived from brain imaging; and to assess the reliability of this method by measuring interobserver and intraobserver agreement.
  
  
  
  The tibial nerve of 20 healthy volunteers (age range = 23-69; mean = 47; standard deviation = 15) was investigated at the ankle level. High-resolution images were obtained through tailored microneurographic sequences, covering 28 mm of nerve length. Two operators manually segmented the nerve using the in-phase image. This region of interest was used to mask the nerve in the water image, and two-class segmentation was performed to measure the fascicular volume, epineurial volume, nerve volume, and fascicular to nerve volume ratio (FNR). Interobserver and intraobserver agreements were calculated.
  
  
  
  The nerve structure was clearly visualized with distinction of the fascicles and the epineurium. Segmentation provided absolute volumes for nerve volume, fascicular volume, and epineurial volume. The mean FNR resulted in 0.69 with a standard deviation of 0.04 and appeared to be not correlated with age and sex. Interobserver and intraobserver agreements were excellent with alpha values >0.9 for each parameter investigated, with measurements free of systematic errors at the Bland-Altman analysis.
  
  
  
  We concluded that the method is reproducible and the parameter FNR is a novel feature that may help in the diagnosis of neuropathies detecting changes in volume of the fascicles or the epineurium.
authors.affiliation: Institute of Radiology, University of Pavia, Viale Camillo Golgi 19, 27100 Pavia PV, Italy. Electronic address: paolo.felisaz@gmail.com.
authors.forename: Paolo Florent
authors.initials: PF
authors.lastname: Felisaz
authors.affiliation: Institute of Radiology, University of Pavia, Viale Camillo Golgi 19, 27100 Pavia PV, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Balducci
authors.affiliation: Institute of Radiology, University of Pavia, Viale Camillo Golgi 19, 27100 Pavia PV, Italy.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Gitto
authors.affiliation: Department of Radiology, IRCCS Salvatore Maugeri Foundation, Scientific Institute of Pavia, Pavia PV, Italy.
authors.forename: Irene
authors.initials: I
authors.lastname: Carne
authors.affiliation: Department of Radiology, IRCCS Salvatore Maugeri Foundation, Scientific Institute of Pavia, Pavia PV, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Montagna
authors.affiliation: Institute of Radiology, University of Pavia, Viale Camillo Golgi 19, 27100 Pavia PV, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: De Icco
authors.affiliation: Department of Neuroradiology, C. Mondino National Neurological Institute, Pavia PV, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Pichiecchio
authors.affiliation: Department of Radiology, IRCCS Salvatore Maugeri Foundation, Scientific Institute of Pavia, Pavia PV, Italy.
authors.forename: Maurizia
authors.initials: M
authors.lastname: Baldi
authors.affiliation: Institute of Radiology, University of Pavia, Viale Camillo Golgi 19, 27100 Pavia PV, Italy; Institute of Radiology, IRCCS Foundation Policlinico San Matteo, Pavia PV, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Calliada
authors.affiliation: Department of Neuroradiology, C. Mondino National Neurological Institute, Pavia PV, Italy; Department of Brain and Behavioral Sciences, University of Pavia, Pavia PV, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Bastianello
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010525:Peripheral Nerves / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D012016:Reference Values; D015203:Reproducibility of Results; D013979:Tibial Nerve / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D055815:Young Adult
keywords: MRI; micro; nerve; neurography; segmentation