title: In vivo DTI tractography of the rat brain: an atlas of the main tracts in Paxinos space with histological comparison.
abstract: Diffusion tensor imaging (DTI) is a magnetic resonance modality that permits to characterize the orientation and integrity of white matter (WM). DTI-based tractography techniques, allowing the virtual reconstruction of WM tract pathways, have found wide application in preclinical neurological research. Recently, anatomically detailed rat brain atlases including DTI data were constructed from ex vivo DTI images, but tractographic atlases of normal rats in vivo are still lacking. We propose here a probabilistic tractographic atlas of the main WM tracts in the healthy rat brain based on in vivo DTI acquisition. Our study was carried out on 10 adult female Sprague-Dawley rats using a 7T preclinical scanner. The MRI protocol permitted a reliable reconstruction of the main rat brain bundles: corpus callosum, cingulum, external capsule, internal capsule, anterior commissure, optic tract. The reconstructed fibers were compared with histological data, proving the viability of in vivo DTI tractography in the rat brain with the proposed acquisition and processing protocol. All the data were registered to a rat brain template in the coordinate system of the commonly used atlas by Paxinos and Watson; then the individual tracts were binarized and averaged, obtaining a probabilistic atlas in Paxinos-Watson space of the main rat brain WM bundles. With respect to the recent high-resolution MRI atlases, the resulting tractographic atlas, available online, provides complementary information about the average anatomical position of the considered WM tracts and their variability between normal animals. Furthermore, reference values for the main DTI-derived parameters, mean diffusivity and fractional anisotropy, were provided. Both these results can be used as references in preclinical studies on pathological rat models involving potential alterations of WM.
authors.affiliation: Scientific Direction, IRCCS Fondazione Istituto Neurologico "C. Besta", Milano, Italy; Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Figini
authors.affiliation: Scientific Direction, IRCCS Fondazione Istituto Neurologico "C. Besta", Milano, Italy. Electronic address: ileana.zucca@istituto-besta.it.
authors.forename: Ileana
authors.initials: I
authors.lastname: Zucca
authors.affiliation: Neuroradiology Department, IRCCS Fondazione Istituto Neurologico "C. Besta", Milano, Italy.
authors.forename: Domenico
authors.initials: D
authors.lastname: Aquino
authors.affiliation: Clinical Epileptology and Experimental Neurophysiology Unit, IRCCS Fondazione Istituto Neurologico "C. Besta", Milano, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Pennacchio
authors.affiliation: Neuroradiology Department, IRCCS Fondazione Istituto Neurologico "C. Besta", Milano, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: Nava
authors.affiliation: Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Di Marzio
authors.affiliation: Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Italy; IRCCS S. Maria Nascente, Fondazione Don Carlo Gnocchi ONLUS, Milano, Italy.
authors.forename: Maria Giulia
authors.initials: MG
authors.lastname: Preti
authors.affiliation: Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Italy.
authors.forename: Guseppe
authors.initials: G
authors.lastname: Baselli
authors.affiliation: Clinical Epileptology and Experimental Neurophysiology Unit, IRCCS Fondazione Istituto Neurologico "C. Besta", Milano, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Spreafico
authors.affiliation: Clinical Epileptology and Experimental Neurophysiology Unit, IRCCS Fondazione Istituto Neurologico "C. Besta", Milano, Italy.
authors.forename: Carolina
authors.initials: C
authors.lastname: Frassoni
mesh_terms: D000818:Animals; D016880:Anisotropy; D001921:Brain / Q000473:pathology*; D001931:Brain Mapping / Q000379:methods; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D009413:Nerve Fibers, Myelinated / Q000473:pathology; D009474:Neurons / Q000473:pathology; D011336:Probability; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values
keywords: DTI; Histology; MRI; Rat brain; Tractographic atlas