title: Magnetic resonance diffusion tensor imaging for the pedunculopontine nucleus: proof of concept and histological correlation.
abstract: The pedunculopontine nucleus (PPN) has been proposed as target for deep brain stimulation (DBS) in patients with postural instability and gait disorders due to its involvement in muscle tonus adjustments and control of locomotion. However, it is a deep-seated brainstem nucleus without clear imaging or electrophysiological markers. Some studies suggested that diffusion tensor imaging (DTI) may help guiding electrode placement in the PPN by showing the surrounding fiber bundles, but none have provided a direct histological correlation. We investigated DTI fractional anisotropy (FA) maps from in vivo and in situ post-mortem magnetic resonance images (MRI) compared to histological evaluations for improving PPN targeting in humans. A post-mortem brain was scanned in a clinical 3T MR system in situ. Thereafter, the brain was processed with a special method ideally suited for cytoarchitectonic analyses. Also, nine volunteers had in vivo brain scanning using the same MRI protocol. Images from volunteers were compared to those obtained in the post-mortem study. FA values of the volunteers were obtained from PPN, inferior colliculus, cerebellar crossing fibers and medial lemniscus using histological data and atlas information. FA values in the PPN were significantly lower than in the surrounding white matter region and higher than in areas with predominantly gray matter. In Nissl-stained histologic sections, the PPN extended for more than 10 mm in the rostro-caudal axis being closely attached to the lateral parabrachial nucleus. Our DTI analyses and the spatial correlation with histological findings proposed a location for PPN that matched the position assigned to this nucleus in the literature. Coregistration of neuroimaging and cytoarchitectonic features can add value to help establishing functional architectonics of the PPN and facilitate neurosurgical targeting of this extended nucleus.
authors.affiliation: Hospital Israelita Albert Einstein, Instituto do Cérebro, São Paulo, Brazil.|Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, Instituto de Radiologia, São Paulo, Brazil.|Grupo de Estudos em Envelhecimento Cerebral e LIM 22, Department of Pathology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: A T D L
authors.initials: ATDL
authors.lastname: Alho
authors.affiliation: Division of Neurosurgery, Toronto Western Hospital, University of Toronto, Centre for Addiction and Mental Health, Toronto, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Hamani
authors.affiliation: Department of Neurology Faculdade de Medicina da Universidade de São Paulo, Divisão de Neurocirurgia Funcional do, Instituto de Psiquiatria-HCFMUSP, São Paulo, Brazil.
authors.forename: E J L
authors.initials: EJL
authors.lastname: Alho
authors.affiliation: Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, Instituto de Radiologia, São Paulo, Brazil.
authors.forename: R E
authors.initials: RE
authors.lastname: da Silva
authors.affiliation: Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, Instituto de Radiologia, São Paulo, Brazil.
authors.forename: G A B
authors.initials: GAB
authors.lastname: Santos
authors.affiliation: Grupo de Estudos em Envelhecimento Cerebral e LIM 22, Department of Pathology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: R C
authors.initials: RC
authors.lastname: Neves
authors.affiliation: Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, Instituto de Radiologia, São Paulo, Brazil.
authors.forename: L L
authors.initials: LL
authors.lastname: Carreira
authors.affiliation: Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, Instituto de Radiologia, São Paulo, Brazil.|Grupo de Estudos em Envelhecimento Cerebral e LIM 22, Department of Pathology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: C M M
authors.initials: CMM
authors.lastname: Araújo
authors.affiliation: Hospital Israelita Albert Einstein, Instituto do Cérebro, São Paulo, Brazil.|Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, Instituto de Radiologia, São Paulo, Brazil.|Grupo de Estudos em Envelhecimento Cerebral e LIM 22, Department of Pathology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: G
authors.initials: G
authors.lastname: Magalhães
authors.affiliation: Escola de Educação Física e Esporte da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: D B
authors.initials: DB
authors.lastname: Coelho
authors.affiliation: Hospital Israelita Albert Einstein, Instituto do Cérebro, São Paulo, Brazil.|Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, Instituto de Radiologia, São Paulo, Brazil.|Memory and Aging Center, Department of Neurology, University of California, San Francisco, USA.
authors.forename: M C
authors.initials: MC
authors.lastname: Alegro
authors.affiliation: Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, Instituto de Radiologia, São Paulo, Brazil.
authors.forename: M G M
authors.initials: MGM
authors.lastname: Martin
authors.affiliation: Grupo de Estudos em Envelhecimento Cerebral e LIM 22, Department of Pathology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.|Department of Pathology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.|Memory and Aging Center, Department of Neurology, University of California, San Francisco, USA.
authors.forename: L T
authors.initials: LT
authors.lastname: Grinberg
authors.affiliation: Grupo de Estudos em Envelhecimento Cerebral e LIM 22, Department of Pathology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.|Department of Pathology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: C A
authors.initials: CA
authors.lastname: Pasqualucci
authors.affiliation: Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, Instituto de Radiologia, São Paulo, Brazil.|Grupo de Estudos em Envelhecimento Cerebral e LIM 22, Department of Pathology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.|Department of Psychiatry, Psychiatric Clinic, Julius-Maximilians-University Würzburg, Universitätsklinikum Würzburg, Würzburg, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Heinsen
authors.affiliation: Department of Neurology Faculdade de Medicina da Universidade de São Paulo, Divisão de Neurocirurgia Funcional do, Instituto de Psiquiatria-HCFMUSP, São Paulo, Brazil. fonoffet@usp.br.
authors.forename: E T
authors.initials: ET
authors.lastname: Fonoff
authors.affiliation: Hospital Israelita Albert Einstein, Instituto do Cérebro, São Paulo, Brazil.|Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, Instituto de Radiologia, São Paulo, Brazil.
authors.forename: E
authors.initials: E
authors.lastname: Amaro
mesh_terms: D000328:Adult; D000368:Aged; D059925:Anatomic Landmarks; D016880:Anisotropy; D001344:Autopsy; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D045042:Pedunculopontine Tegmental Nucleus / Q000000981:diagnostic imaging* / Q000473:pathology*; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D055815:Young Adult
keywords: Deep brain stimulation; Diffusion tensor imaging; Histology; Pedunculopontine nucleus