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Yang R, Lin TH, Zhan J, Lai S, Song C, Sun P, Ye Z, Wallendorf M, George A, Cross AH, Song SK. Diffusion basis spectrum imaging measures anti-inflammatory and neuroprotective effects of fingolimod on murine optic neuritis. NEUROIMAGE-CLINICAL 2021; 31:102732. [PMID: 34166868 PMCID: PMC8240023 DOI: 10.1016/j.nicl.2021.102732] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 06/12/2021] [Accepted: 06/14/2021] [Indexed: 10/30/2022]
Abstract
OBJECTIVE To prospectively determine whether diffusion basis spectrum imaging (DBSI) detects, differentiates and quantitates coexisting inflammation, demyelination, axonal injury and axon loss in mice with optic neuritis (ON) due to experimental autoimmune encephalomyelitis (EAE), and to determine if DBSI accurately measures effects of fingolimod on underlying pathology. METHODS EAE was induced in 7-week-old C57BL/6 female mice. Visual acuity (VA) was assessed daily to detect onset of ON after which daily oral-treatment with either fingolimod (1 mg/kg) or saline was given for ten weeks. In vivo DBSI scans of optic nerves were performed at baseline, 2-, 6- and 10-weeks post treatment. DBSI-derived metrics including restricted isotropic diffusion tensor fraction (putatively reflecting cellularity), non-restricted isotropic diffusion tensor fraction (putatively reflecting vasogenic edema), DBSI-derived axonal volume, axial diffusivity, λ∥ (putatively reflecting axonal integrity), and increased radial diffusivity, λ⊥ (putatively reflecting demyelination). Mice were killed immediately after the last DBSI scan for immunohistochemical assessment. RESULTS Optic nerves of fingolimod-treated mice exhibited significantly better (p < 0.05) VA than saline-treated group at each time point. During ten-week of treatment, DBSI-derived non-restricted and restricted-isotropic-diffusion-tensor fractions, and axonal volumes were not significantly different (p > 0.05) from the baseline values in fingolimod-treated mice. Transient DBSI-λ∥ decrease and DBSI-λ⊥ increase were detected during Fingolimod treatment. DBSI-derived metrics assessed in vivo significantly correlated (p < 0.05) with the corresponding histological markers. CONCLUSION DBSI was used to assess changes of the underlying optic nerve pathologies in EAE mice with ON, exhibiting great potential as a noninvasive outcome measure for monitoring disease progression and therapeutic efficacy for MS.
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Affiliation(s)
- Ruimeng Yang
- Department of Radiology, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, Guangdong 510640, China; Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Tsen-Hsuan Lin
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jie Zhan
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Shengsheng Lai
- Department of Medical Equipment, Guangdong Food and Drug Vocational College, Guangzhou, Guangdong 510520, China
| | - Chunyu Song
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Peng Sun
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Zezhong Ye
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Michael Wallendorf
- Department of Biostatistics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Ajit George
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Anne H Cross
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Sheng-Kwei Song
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO 63130, USA.
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Zhang Z, Vernekar D, Qian W, Kim M. Non-local means based Rician noise filtering for diffusion tensor and kurtosis imaging in human brain and spinal cord. BMC Med Imaging 2021; 21:16. [PMID: 33516178 PMCID: PMC7847150 DOI: 10.1186/s12880-021-00549-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 01/18/2021] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND To investigate the effect of using a Rician nonlocal means (NLM) filter on quantification of diffusion tensor (DT)- and diffusion kurtosis (DK)-derived metrics in various anatomical regions of the human brain and the spinal cord, when combined with a constrained linear least squares (CLLS) approach. METHODS Prospective brain data from 9 healthy subjects and retrospective spinal cord data from 5 healthy subjects from a 3 T MRI scanner were included in the study. Prior to tensor estimation, registered diffusion weighted images were denoised by an optimized blockwise NLM filter with CLLS. Mean kurtosis (MK), radial kurtosis (RK), axial kurtosis (AK), mean diffusivity (MD), radial diffusivity (RD), axial diffusivity (AD) and fractional anisotropy (FA), were determined in anatomical structures of the brain and the spinal cord. DTI and DKI metrics, signal-to-noise ratio (SNR) and Chi-square values were quantified in distinct anatomical regions for all subjects, with and without Rician denoising. RESULTS The averaged SNR significantly increased with Rician denoising by a factor of 2 while the averaged Chi-square values significantly decreased up to 61% in the brain and up to 43% in the spinal cord after Rician NLM filtering. In the brain, the mean MK varied from 0.70 (putamen) to 1.27 (internal capsule) while AK and RK varied from 0.58 (corpus callosum) to 0.92 (cingulum) and from 0.70 (putamen) to 1.98 (corpus callosum), respectively. In the spinal cord, FA varied from 0.78 in lateral column to 0.81 in dorsal column while MD varied from 0.91 × 10-3 mm2/s (lateral) to 0.93 × 10-3 mm2/s (dorsal). RD varied from 0.34 × 10-3 mm2/s (dorsal) to 0.38 × 10-3 mm2/s (lateral) and AD varied from 1.96 × 10-3 mm2/s (lateral) to 2.11 × 10-3 mm2/s (dorsal). CONCLUSIONS Our results show a Rician denoising NLM filter incorporated with CLLS significantly increases SNR and reduces estimation errors of DT- and KT-derived metrics, providing the reliable metrics estimation with adequate SNR levels.
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Affiliation(s)
- Zhongping Zhang
- Department of Diagnostic Radiology, The University of Hong Kong, Hong Kong SAR, China.,Philips Healthcare, Shanghai, China
| | - Dhanashree Vernekar
- Department of Diagnostic Radiology, The University of Hong Kong, Hong Kong SAR, China
| | - Wenshu Qian
- Department of Diagnostic Radiology, The University of Hong Kong, Hong Kong SAR, China.,Laboratory of Clinical Investigation, National Institute on Aging, NIH, Baltimore, USA
| | - Mina Kim
- Department of Diagnostic Radiology, The University of Hong Kong, Hong Kong SAR, China. .,Department of Neuroinflammation, Faculty of Brain Sciences, UCL Queen Square Institute of Neurology, London, UK.
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Zaninovich OA, Avila MJ, Kay M, Becker JL, Hurlbert RJ, Martirosyan NL. The role of diffusion tensor imaging in the diagnosis, prognosis, and assessment of recovery and treatment of spinal cord injury: a systematic review. Neurosurg Focus 2020; 46:E7. [PMID: 30835681 DOI: 10.3171/2019.1.focus18591] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 01/07/2019] [Indexed: 12/19/2022]
Abstract
OBJECTIVEDiffusion tensor imaging (DTI) is an MRI tool that provides an objective, noninvasive, in vivo assessment of spinal cord injury (SCI). DTI is significantly better at visualizing microstructures than standard MRI sequences. In this imaging modality, the direction and amplitude of the diffusion of water molecules inside tissues is measured, and this diffusion can be measured using a variety of parameters. As a result, the potential clinical application of DTI has been studied in several spinal cord pathologies, including SCI. The aim of this study was to describe the current state of the potential clinical utility of DTI in patients with SCI and the challenges to its use as a tool in clinical practice.METHODSA search in the PubMed database was conducted for articles relating to the use of DTI in SCI. The citations of relevant articles were also searched for additional articles.RESULTSAmong the most common DTI metrics are fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity. Changes in these metrics reflect changes in tissue integrity. Several DTI metrics and combinations thereof have demonstrated significant correlations with clinical function both in model species and in humans. Its applications encompass the full spectrum of the clinical assessment of SCI including diagnosis, prognosis, recovery, and efficacy of treatments in both the spinal cord and potentially the brain.CONCLUSIONSDTI and its metrics have great potential to become a powerful clinical tool in SCI. However, the current limitations of DTI preclude its use beyond research and into clinical practice. Further studies are needed to significantly improve and resolve these limitations as well as to determine reliable time-specific changes in multiple DTI metrics for this tool to be used accurately and reliably in the clinical setting.
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Affiliation(s)
| | | | - Matthew Kay
- 3Department of Medical Imaging, University of Arizona, Tucson, Arizona
| | - Jennifer L Becker
- 3Department of Medical Imaging, University of Arizona, Tucson, Arizona
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Epprecht L, Kozin ED, Piccirelli M, Kanumuri VV, Tarabichi O, Remenschneider A, Barker FG, McKenna MJ, Huber AM, Cunnane ME, Reinshagen KL, Lee DJ. Super-resolution Diffusion Tensor Imaging for Delineating the Facial Nerve in Patients with Vestibular Schwannoma. J Neurol Surg B Skull Base 2019; 80:648-654. [PMID: 31754597 DOI: 10.1055/s-0039-1677864] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 12/16/2018] [Indexed: 10/27/2022] Open
Abstract
Objectives Predicting the course of cranial nerves (CNs) VII and VIII in the cerebellopontine angle on preoperative imaging for vestibular schwannoma (VS) may help guide surgical resection and reduce complications. Diffusion magnetic resonance imaging dMRI is commonly used for this purpose, but is limited by its resolution. We investigate the use of super-resolution reconstruction (SRR), where several different dMRIs are combined into one dataset. We hypothesize that SRR improves the visualization of the CN VII and VIII. Design Retrospective case review. Setting Tertiary referral center. SRR was performed on the basis of axial and parasagittal single-shot epiplanar diffusion tensor imaging on a 3.0-tesla MRI scanner. Participants Seventeen adult patients with suspected neoplasms of the lateral skull base. Main Outcome Measures We assessed separability of the two distinct nerves on fractional anisotropy (FA) maps, the tractography of the nerves through the cerebrospinal fluid (CSF), and FA in the CSF as a measure of noise. Results SRR increases separability of the CN VII and VIII (16/17 vs. 0/17, p = 0.008). Mean FA of CSF surrounding the nerves is significantly lower in SRRs (0.07 ± 0.02 vs. 0.13 ± 0.03 [axial images]/0.14 ± 0.05 [parasagittal images], p = 0.00003/ p = 0.00005). Combined scanning times (parasagittal and axial) used for SRR were shorter (8 minute 25 seconds) than a comparable high-resolution scan (15 minute 17 seconds). Conclusion SRR improves the resolution of CN VII and VIII. The technique can be readily applied in the clinical setting, improving surgical counseling and planning in patients with VS.
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Affiliation(s)
- Lorenz Epprecht
- Eaton Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States.,Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts, United States
| | - Elliott D Kozin
- Eaton Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States.,Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts, United States
| | - Marco Piccirelli
- Department of Neuroradiology, University Hospital of Zurich, Zurich, Switzerland.,Clinical Neuroscience Center, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Vivek V Kanumuri
- Eaton Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States.,Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts, United States
| | - Osama Tarabichi
- Eaton Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States.,Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts, United States
| | - Aaron Remenschneider
- Eaton Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States.,Department of Otolaryngology, University of Massachusetts Medical School, Boston, Massachusetts, United States
| | - Frederick G Barker
- Department of Neurosurgery, Massachusetts General Hospital, Boston Massachusetts, United States
| | - Michael J McKenna
- Eaton Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States.,Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts, United States
| | - Alexander M Huber
- Department of Otorhinolaryngology and Head and Neck Surgery, University Hospital of Zurich, Zurich, Switzerland
| | - Marybeth E Cunnane
- Department of Radiology, Massachusetts Eye and Ear Infirmary and Harvard Medical School, Boston, Massachusetts, United States
| | - Katherine L Reinshagen
- Department of Radiology, Massachusetts Eye and Ear Infirmary and Harvard Medical School, Boston, Massachusetts, United States
| | - Daniel J Lee
- Eaton Peabody Laboratories, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States.,Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts, United States
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MRI-based assessment of function and dysfunction in myelinated axons. Proc Natl Acad Sci U S A 2018; 115:E10225-E10234. [PMID: 30297414 DOI: 10.1073/pnas.1801788115] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Repetitive electrical activity produces microstructural alteration in myelinated axons, which may afford the opportunity to noninvasively monitor function of myelinated fibers in peripheral nervous system (PNS)/CNS pathways. Microstructural changes were assessed via two different magnetic-resonance-based approaches: diffusion fMRI and dynamic T2 spectroscopy in the ex vivo perfused bullfrog sciatic nerves. Using this robust, classical model as a platform for testing, we demonstrate that noninvasive diffusion fMRI, based on standard diffusion tensor imaging (DTI), can clearly localize the sites of axonal conduction blockage as might be encountered in neurotrauma or other lesion types. It is also shown that the diffusion fMRI response is graded in proportion to the total number of electrical impulses carried through a given locus. Dynamic T2 spectroscopy of the perfused frog nerves point to an electrical-activity-induced redistribution of tissue water and myelin structural changes. Diffusion basis spectrum imaging (DBSI) reveals a reversible shift of tissue water into a restricted isotropic diffusion signal component. Submyelinic vacuoles are observed in electron-microscopy images of tissue fixed during electrical stimulation. A slowing of the compound action potential conduction velocity accompanies repetitive electrical activity. Correlations between electrophysiology and MRI parameters during and immediately after stimulation are presented. Potential mechanisms and interpretations of these results are discussed.
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Lin TH, Chiang CW, Perez-Torres CJ, Sun P, Wallendorf M, Schmidt RE, Cross AH, Song SK. Diffusion MRI quantifies early axonal loss in the presence of nerve swelling. J Neuroinflammation 2017; 14:78. [PMID: 28388913 PMCID: PMC5384143 DOI: 10.1186/s12974-017-0852-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 03/26/2017] [Indexed: 11/10/2022] Open
Abstract
Background Magnetic resonance imaging markers have been widely used to detect and quantify white matter pathologies in multiple sclerosis. We have recently developed a diffusion basis spectrum imaging (DBSI) to distinguish and quantify co-existing axonal injury, demyelination, and inflammation in multiple sclerosis patients and animal models. It could serve as a longitudinal marker for axonal loss, a primary cause of permanent neurological impairments and disease progression. Methods Eight 10-week-old female C57BL/6 mice underwent optic nerve DBSI, followed by a week-long recuperation prior to active immunization for experimental autoimmune encephalomyelitis (EAE). Visual acuity of all mice was assessed daily. Longitudinal DBSI was performed in mouse optic nerves at baseline (naïve, before immunization), before, during, and after the onset of optic neuritis. Tissues were perfusion fixed after final in vivo scans. The correlation between DBSI detected pathologies and corresponding immunohistochemistry markers was quantitatively assessed. Results In this cohort of EAE mice, monocular vision impairment occurred in all animals. In vivo DBSI detected, differentiated, and quantified optic nerve inflammation, demyelination, and axonal injury/loss, correlating nerve pathologies with visual acuity at different time points of acute optic neuritis. DBSI quantified, in the presence of optic nerve swelling, ~15% axonal loss at the onset of optic neuritis in EAE mice. Conclusions Our findings support the notion that axonal loss could occur early in EAE mice. DBSI detected pathologies in the posterior visual pathway unreachable by optical coherence tomography and without confounding inflammation induced optic nerve swelling. DBSI could thus decipher the interrelationship among various pathological components and the role each plays in disease progression. Quantification of the rate of axonal loss could potentially serve as the biomarker to predict treatment outcome and to determine when progressive disease starts.
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Affiliation(s)
- Tsen-Hsuan Lin
- Radiology, Washington University School of Medicine, 660 S Euclid Ave, St. Louis, MO, 63110, USA
| | - Chia-Wen Chiang
- Radiology, Washington University School of Medicine, 660 S Euclid Ave, St. Louis, MO, 63110, USA.,Current Address: Institute of Biomedical Engineering and Nanomedicine, National Health Research Institute, 35 Keyan Road, Zhunan, Miaoli County, 35053, Taiwan
| | - Carlos J Perez-Torres
- Radiology, Washington University School of Medicine, 660 S Euclid Ave, St. Louis, MO, 63110, USA.,Current Address: School of Health Sciences, Purdue University, 550 W Stadium Ave, West Lafayette, IN, 47907, USA
| | - Peng Sun
- Radiology, Washington University School of Medicine, 660 S Euclid Ave, St. Louis, MO, 63110, USA
| | - Michael Wallendorf
- Biostatistics, Washington University School of Medicine, 660 S Euclid Ave, St. Louis, MO, 63110, USA
| | - Robert E Schmidt
- Pathology, Washington University School of Medicine, 660 S Euclid Ave, St. Louis, MO, 63110, USA
| | - Anne H Cross
- Neurology, Washington University School of Medicine, 660 S Euclid Ave, St. Louis, MO, 63110, USA.,Hope Center for Neurological Disorders, Washington University School of Medicine, 660 S Euclid Ave, St. Louis, MO, 63110, USA
| | - Sheng-Kwei Song
- Radiology, Washington University School of Medicine, 660 S Euclid Ave, St. Louis, MO, 63110, USA. .,Hope Center for Neurological Disorders, Washington University School of Medicine, 660 S Euclid Ave, St. Louis, MO, 63110, USA. .,Biomedical Engineering, Washington University, 1 Brookings Dr, St. Louis, MO, 63130, USA. .,Biomedical MR Laboratory, Washington University School of Medicine, Campus Box 8227, Room 2313, 4525 Scott Ave, St Louis, MO, 63110, USA.
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Figini M, Scotti A, Marcuzzo S, Bonanno S, Padelli F, Moreno-Manzano V, García-Verdugo JM, Bernasconi P, Mantegazza R, Bruzzone MG, Zucca I. Comparison of Diffusion MRI Acquisition Protocols for the In Vivo Characterization of the Mouse Spinal Cord: Variability Analysis and Application to an Amyotrophic Lateral Sclerosis Model. PLoS One 2016; 11:e0161646. [PMID: 27560686 PMCID: PMC4999133 DOI: 10.1371/journal.pone.0161646] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Accepted: 08/09/2016] [Indexed: 11/18/2022] Open
Abstract
Diffusion-weighted Magnetic Resonance Imaging (dMRI) has relevant applications in the microstructural characterization of the spinal cord, especially in neurodegenerative diseases. Animal models have a pivotal role in the study of such diseases; however, in vivo spinal dMRI of small animals entails additional challenges that require a systematical investigation of acquisition parameters. The purpose of this study is to compare three acquisition protocols and identify the scanning parameters allowing a robust estimation of the main diffusion quantities and a good sensitivity to neurodegeneration in the mouse spinal cord. For all the protocols, the signal-to-noise and contrast-to noise ratios and the mean value and variability of Diffusion Tensor metrics were evaluated in healthy controls. For the estimation of fractional anisotropy less variability was provided by protocols with more diffusion directions, for the estimation of mean, axial and radial diffusivity by protocols with fewer diffusion directions and higher diffusion weighting. Intermediate features (12 directions, b = 1200 s/mm2) provided the overall minimum inter- and intra-subject variability in most cases. In order to test the diagnostic sensitivity of the protocols, 7 G93A-SOD1 mice (model of amyotrophic lateral sclerosis) at 10 and 17 weeks of age were scanned and the derived diffusion parameters compared with those estimated in age-matched healthy animals. The protocols with an intermediate or high number of diffusion directions provided the best differentiation between the two groups at week 17, whereas only few local significant differences were highlighted at week 10. According to our results, a dMRI protocol with an intermediate number of diffusion gradient directions and a relatively high diffusion weighting is optimal for spinal cord imaging. Further work is needed to confirm these results and for a finer tuning of acquisition parameters. Nevertheless, our findings could be important for the optimization of acquisition protocols for preclinical and clinical dMRI studies on the spinal cord.
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Affiliation(s)
- Matteo Figini
- Scientific Direction, Fondazione IRCCS Istituto Neurologico “Carlo Besta” Milan, Italy
- * E-mail:
| | - Alessandro Scotti
- Scientific Direction, Fondazione IRCCS Istituto Neurologico “Carlo Besta” Milan, Italy
| | - Stefania Marcuzzo
- Neurology IV—Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico “Carlo Besta”, Milan, Italy
| | - Silvia Bonanno
- Neurology IV—Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico “Carlo Besta”, Milan, Italy
| | - Francesco Padelli
- Scientific Direction, Fondazione IRCCS Istituto Neurologico “Carlo Besta” Milan, Italy
| | - Victoria Moreno-Manzano
- Neuronal and Tissue Regeneration Laboratory, Centro de Investigación Príncipe Felipe, Valencia, Spain
| | | | - Pia Bernasconi
- Neurology IV—Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico “Carlo Besta”, Milan, Italy
| | - Renato Mantegazza
- Neurology IV—Neuroimmunology and Neuromuscular Diseases Unit, Fondazione IRCCS Istituto Neurologico “Carlo Besta”, Milan, Italy
| | | | - Ileana Zucca
- Scientific Direction, Fondazione IRCCS Istituto Neurologico “Carlo Besta” Milan, Italy
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Imaging of spontaneous ventriculomegaly and vascular malformations in Wistar rats: implications for preclinical research. J Neuropathol Exp Neurol 2015; 73:1152-65. [PMID: 25383642 DOI: 10.1097/nen.0000000000000140] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Wistar rats are widely used in biomedical research and commonly serve as a model organism in neuroscience studies. In most cases when noninvasive imaging is not used, studies assume a consistent baseline condition in rats that lack visible differences. While performing a series of traumatic brain injury studies, we discovered mild spontaneous ventriculomegaly in 70 (43.2%) of 162 Wistar rats that had been obtained from 2 different vendors. Advanced magnetic resonance (MR) imaging techniques, including MR angiography and diffusion tensor imaging, were used to evaluate the rats. Multiple neuropathologic abnormalities, including presumed arteriovenous malformations, aneurysms, cysts, white matter lesions, and astrogliosis were found in association with ventriculomegaly. Postmortem microcomputed tomography and immunohistochemical staining confirmed the presence of aneurysms and arteriovenous malformations. Diffusion tensor imaging showed significant decreases in fractional anisotropy and increases in mean diffusivity, axial diffusivity, and radial diffusivity in multiple white matter tracts (p < 0.05). These results could impact the interpretation, for example, of a pseudo-increase of axon integrity and a pseudo-decrease of myelin integrity, based on characteristics intrinsic to rats with ventriculomegaly. We suggest the use of baseline imaging to prevent the inadvertent introduction of a high degree of variability in preclinical studies of neurologic disease or injury in Wistar rats.
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