title: Prospective estimation of mean axon diameter and extra-axonal space of the posterior limb of the internal capsule in patients with idiopathic normal pressure hydrocephalus before and after a lumboperitoneal shunt by using q-space diffusion MRI.
abstract: OBJECTIVE
  To prospectively estimate the mean axon diameter (MAD) and extracellular space of the posterior limb of the internal capsule (PLIC) in patients with idiopathic normal pressure hydrocephalus (iNPH) before and after a lumboperitoneal (LP) shunting operation using q-space diffusion MRI analysis.
  
  
  METHODS
  We studied 12 consecutive patients with iNPH and 12 controls at our institution. After conventional magnetic resonance imaging (MRI), q-space image (QSI) data were acquired with a 3-T MRI scanner. The MAD and extra-axonal space of the PLIC before and after LP shunting were calculated using two-component q-space imaging analyses; the before and after values were compared.
  
  
  RESULTS
  After LP shunt surgery, the extracellular space of the PLIC was significantly higher than that of the same patients before the operation (one-way analysis of variance (ANOVA) with Scheffé's post-hoc test, P = 0.024). No significant differences were observed in the PLIC axon diameters among normal controls or in patients before and after surgery.
  
  
  CONCLUSIONS
  Increases in the root mean square displacement in the extra-axonal space of the PLIC in patients with iNPH after an LP shunt procedure are associated with the microstructural changes of white matter and subsequent abatement of patient symptoms.
  
  
  CONCLUSIONS
  • Q-space diffusion MRI provides information on microstructural changes in the corticospinal tract • Lumboperitoneal (LP) shunting operation is useful for idiopathic normal pressure hydrocephalus • Q-space measurement may be a biomarker for the effect of the LP shunt procedure.
authors.affiliation: Department of Radiology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan. mahori@juntendo.ac.jp.
authors.forename: Masaaki
authors.identifier: http://orcid.org/0000-0002-1791-8032
authors.initials: M
authors.lastname: Hori
authors.affiliation: Department of Radiology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.|Department of Radiology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
authors.forename: Kouhei
authors.initials: K
authors.lastname: Kamiya
authors.affiliation: Department of Radiology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Nakanishi
authors.affiliation: Department of Radiology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.|Department of Health Science, Graduate School of Human Health Sciences, Tokyo Metropolitan University, 7-2-10, Higashiogu, Arakawa-ku, Tokyo, 116-8551, Japan.
authors.forename: Issei
authors.initials: I
authors.lastname: Fukunaga
authors.affiliation: Department of Neurosurgery, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Miyajima
authors.affiliation: Department of Neurosurgery, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
authors.forename: Madoka
authors.initials: M
authors.lastname: Nakajima
authors.affiliation: Department of Radiology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
authors.forename: Michimasa
authors.initials: M
authors.lastname: Suzuki
authors.affiliation: Department of Radiology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.|C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, 2333 ZA, Netherlands.
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Suzuki
authors.affiliation: Department of Radiology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.|Department of Radiology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
authors.forename: Ryusuke
authors.initials: R
authors.lastname: Irie
authors.affiliation: Department of Radiology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Kamagata
authors.affiliation: Department of Neurosurgery, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Arai
authors.affiliation: Department of Radiology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Aoki
mesh_terms: D000368:Aged; D001369:Axons; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000000981:diagnostic imaging* / Q000601:surgery*; D020772:Internal Capsule / Q000000981:diagnostic imaging*; D008297:Male; D011446:Prospective Studies; D011712:Pyramidal Tracts / Q000000981:diagnostic imaging
keywords: Axon diameter; Diffusion MRI; Idiopathic NPH; Lumboperitoneal shunt; Q-space imaging