Ultra-deep through-skull mouse brain imaging via the combination of skull optical clearing and three-photon microscopy

Optical microscopy has enabled in vivo monitoring of brain structures and functions with high spatial resolution. However, the strong optical scattering in turbid brain tissue and skull impedes the observation of microvasculature and neuronal structures at large depth. Herein, we proposed a strategy to overcome the influence induced by the high scattering effect of both skull and brain tissue via the combination of skull optical clearing (SOC) technique and thee-photon fluorescence microscopy (3PM). The Visible-NIR-II compatible Skull Optical Clearing Agents (VNSOCA) we applied reduced the skull scattering and water absorption in long wavelength by refractive index matching and H2O replacement to D2O respectively. 3PM with the excitation in the 1300-nm window reached 1.5 mm cerebrovascular imaging depth in cranial window. Combining the two advanced technologies together, we achieved so far the largest cerebrovascular imaging depth of 1 mm and neuronal imaging depth of >700 μm through intact mouse skull. Dual-channel through-skull imaging of both brain vessels and neurons was also successfully realized, giving an opportunity of non-invasively monitoring the deep brain structures and functions at single-cell level simultaneously.

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Imaging depth extension of optical coherence tomography in rabbit eyes using optical clearing agents

Experimental Biology and Medicine ◽

10.1177/1535370220949834 ◽

2020 ◽

Vol 245 (18) ◽

pp. 1629-1636

Author(s):

Ruiming Kong ◽

Wenjuan Wu ◽

Rui Qiu ◽

Lei Gao ◽

Fengxian Du ◽

...

Keyword(s):

Optical Coherence Tomography ◽

Ex Vivo ◽

Light Attenuation ◽

Anterior Segment ◽

Posterior Segment ◽

Glycerol Solution ◽

Optical Coherence ◽

Optical Clearing ◽

Imaging Depth

Optical coherence tomography has become an indispensable diagnostic tool in ophthalmology for imaging the retina and the anterior segment of the eye. However, the imaging depth of optical coherence tomography is limited by light attenuation in tissues due to optical scattering and absorption. In this study of rabbit eye both ex vivo and in vivo, optical coherence tomography imaging depth of the anterior and posterior segments of the eye was extended by using optical clearing agents to reduce multiple scattering. The sclera, the iris, and the ciliary body were clearly visualized by direct application of glycerol at an incision on the conjunctiva, and the posterior boundary of sclera and even the deeper tissues were detected by submerging the posterior segment of eye in glycerol solution ex vivo or by retro-bulbar injection of glycerol in vivo. The ex vivo rabbit eyes recovered to their original state in 60 s after saline-wash treatment, and normal optical coherence tomography images of the posterior segment of the sample eyes proved the self-recovery of in vivo performance. Signal intensities of optical coherence tomography images obtained before and after glycerol treatment were compared to analysis of the effect of optical clearing. To the best of our knowledge, this is the first study for imaging depth extension of optical coherence tomography in both the anterior and posterior segments of eye by using optical clearing agents.

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TMOD-37. IN VIVO COMPRESSION AND IMAGING FOR CAUSAL STUDIES OF MECHANICAL FORCES IN THE BRAIN

Neuro-Oncology ◽

10.1093/neuonc/noaa215.987 ◽

2020 ◽

Vol 22 (Supplement_2) ◽

pp. ii235-ii236

Author(s):

Meenal Datta ◽

Hadi Nia ◽

Giorgio Seano ◽

Sylvie Roberge ◽

Peigen Huang ◽

...

Keyword(s):

Brain Tissue ◽

Biological Effects ◽

Neurological Dysfunction ◽

Normal Brain ◽

Mechanical Forces ◽

Mechanistic Studies ◽

Cranial Window ◽

Solid Stress ◽

The Brain

Abstract Clinicians have long observed the effects of abnormal mechanical forces – edema (fluid pressure) in particular – in brain tumors and the surrounding normal brain tissue. However, it was not previously possible to dissect the direct effects of solid stress (i.e., “mass effect”), a mechanopathology resulting from solid components of the tumor tissue, on the brain from the biological and physiological adverse effects exerted by cancer cells. We recently developed for the first time an in vivo compression device that allows for causal and mechanistic studies that delineate the solid mechanical forces of a tumor growing in the brain from its biological effects. The brain poses a unique anatomical consideration of abnormal mechanical forces due to its physical confinement by the skull. We adapted standard transparent cranial windows normally used for intravital imaging studies in mice to include a tunable screw for controlled and acute or chronic compression and decompression in the brain. This compressive cranial window allows for longitudinal imaging of the surrounding brain tissue (cortex or cerebellum) over time (weeks or months) as the screw is lowered further into the brain tissue to recapitulate tumor growth-induced solid stress. Using this device, we have demonstrated that solid stress is causally linked to vascular and neurological dysfunction in the brain. We have also been able to utilize this preclinical system to screen for effective therapeutic interventions to reduce solid stress-induced neuronal death and improve neurological function. Beyond cancer, this technique can be used to study a variety of diseases or disorders that present with abnormal solid masses in the brain, including cysts and benign growths. Thus, mechanistic studies enabled by the compressive cranial window can elucidate the role of mechanics in brain tumor progression, and reveal novel targets for treatment.

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Improving imaging depth by dynamic laser speckle imaging and topical optical clearing for in vivo blood flow monitoring

Lasers in Medical Science ◽

10.1007/s10103-020-03059-2 ◽

2020 ◽

Author(s):

Xu Sang ◽

Dong Li ◽

Bin Chen

Keyword(s):

Blood Flow ◽

Laser Speckle ◽

Laser Speckle Imaging ◽

Speckle Imaging ◽

Optical Clearing ◽

Flow Monitoring ◽

Imaging Depth

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Faculty Opinions recommendation of In vivo three-photon microscopy of subcortical structures within an intact mouse brain.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.718303489.793492009 ◽

2014 ◽

Author(s):

Joe Fetcho

Keyword(s):

Mouse Brain ◽

Subcortical Structures ◽

Intact Mouse

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Monocytes as Carriers of Magnetic Nanoparticles for Tracking Inflammation in the Epileptic Rat Brain

Current Drug Delivery ◽

10.2174/1567201816666190619122456 ◽

2019 ◽

Vol 16 (7) ◽

pp. 637-644 ◽

Cited By ~ 4

Author(s):

Hadas Han ◽

Sara Eyal ◽

Emma Portnoy ◽

Aniv Mann ◽

Miriam Shmuel ◽

...

Keyword(s):

Brain Tissue ◽

Ex Vivo ◽

In Vivo Studies ◽

Nanoparticle Distribution ◽

Spontaneous Seizures ◽

Systemic Distribution ◽

Hippocampal Ca1 ◽

Pilocarpine Model

Background: Inflammation is a hallmark of epileptogenic brain tissue. Previously, we have shown that inflammation in epilepsy can be delineated using systemically-injected fluorescent and magnetite- laden nanoparticles. Suggested mechanisms included distribution of free nanoparticles across a compromised blood-brain barrier or their transfer by monocytes that infiltrate the epileptic brain. Objective: In the current study, we evaluated monocytes as vehicles that deliver nanoparticles into the epileptic brain. We also assessed the effect of epilepsy on the systemic distribution of nanoparticleloaded monocytes. Methods: The in vitro uptake of 300-nm nanoparticles labeled with magnetite and BODIPY (for optical imaging) was evaluated using rat monocytes and fluorescence detection. For in vivo studies we used the rat lithium-pilocarpine model of temporal lobe epilepsy. In vivo nanoparticle distribution was evaluated using immunohistochemistry. Results: 89% of nanoparticle loading into rat monocytes was accomplished within 8 hours, enabling overnight nanoparticle loading ex vivo. The dose-normalized distribution of nanoparticle-loaded monocytes into the hippocampal CA1 and dentate gyrus of rats with spontaneous seizures was 176-fold and 380-fold higher compared to the free nanoparticles (p<0.05). Seizures were associated with greater nanoparticle accumulation within the liver and the spleen (p<0.05). Conclusion: Nanoparticle-loaded monocytes are attracted to epileptogenic brain tissue and may be used for labeling or targeting it, while significantly reducing the systemic dose of potentially toxic compounds. The effect of seizures on monocyte biodistribution should be further explored to better understand the systemic effects of epilepsy.

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Protein Kinase A Distribution in Meningioma

Cancers ◽

10.3390/cancers11111686 ◽

2019 ◽

Vol 11 (11) ◽

pp. 1686 ◽

Cited By ~ 1

Author(s):

Caretta ◽

Denaro ◽

D’Avella ◽

Mucignat-Caretta

Keyword(s):

Brain Tissue ◽

Catalytic Subunit ◽

Therapeutic Interventions ◽

Normal Brain ◽

Local Concentration ◽

Correlation Pattern ◽

Catalytic Subunits ◽

Tissue Specimens ◽

Pka Catalytic Subunit

Deregulation of intracellular signal transduction pathways is a hallmark of cancer cells, clearly differentiating them from healthy cells. Differential intracellular distribution of the cAMP-dependent protein kinases (PKA) was previously detected in cell cultures and in vivo in glioblastoma and medulloblastoma. Our goal is to extend this observation to meningioma, to explore possible differences among tumors of different origins and prospective outcomes. The distribution of regulatory and catalytic subunits of PKA has been examined in tissue specimens obtained during surgery from meningioma patients. PKA RI subunit appeared more evenly distributed throughout the cytoplasm, but it was clearly detectable only in some tumors. RII was present in discrete spots, presumably at high local concentration; these aggregates could also be visualized under equilibrium binding conditions with fluorescent 8-substituted cAMP analogues, at variance with normal brain tissue and other brain tumors. The PKA catalytic subunit showed exactly overlapping pattern to RII and in fixed sections could be visualized by fluorescent cAMP analogues. Gene expression analysis showed that the PKA catalytic subunit revealed a significant correlation pattern with genes involved in meningioma. Hence, meningioma patients show a distinctive distribution pattern of PKA regulatory and catalytic subunits, different from glioblastoma, medulloblastoma, and healthy brain tissue. These observations raise the possibility of exploiting the PKA intracellular pathway as a diagnostic tool and possible therapeutic interventions.

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Whole-brain 3D MR fingerprinting brain imaging: clinical validation and feasibility to patients with meningioma

Magnetic Resonance Materials in Physics Biology and Medicine ◽

10.1007/s10334-021-00924-1 ◽

2021 ◽

Author(s):

Thomaz R. Mostardeiro ◽

Ananya Panda ◽

Robert J. Witte ◽

Norbert G. Campeau ◽

Kiaran P. McGee ◽

...

Keyword(s):

White Matter ◽

Statistical Significance ◽

Relaxation Times ◽

Brain Structures ◽

Centrum Semiovale ◽

In Vivo Evaluation ◽

Whole Brain ◽

Mean Values ◽

Caudate Head

Abstract Purpose MR fingerprinting (MRF) is a MR technique that allows assessment of tissue relaxation times. The purpose of this study is to evaluate the clinical application of this technique in patients with meningioma. Materials and methods A whole-brain 3D isotropic 1mm3 acquisition under a 3.0T field strength was used to obtain MRF T1 and T2-based relaxometry values in 4:38 s. The accuracy of values was quantified by scanning a quantitative MR relaxometry phantom. In vivo evaluation was performed by applying the sequence to 20 subjects with 25 meningiomas. Regions of interest included the meningioma, caudate head, centrum semiovale, contralateral white matter and thalamus. For both phantom and subjects, mean values of both T1 and T2 estimates were obtained. Statistical significance of differences in mean values between the meningioma and other brain structures was tested using a Friedman’s ANOVA test. Results MR fingerprinting phantom data demonstrated a linear relationship between measured and reference relaxometry estimates for both T1 (r2 = 0.99) and T2 (r2 = 0.97). MRF T1 relaxation times were longer in meningioma (mean ± SD 1429 ± 202 ms) compared to thalamus (mean ± SD 1054 ± 58 ms; p = 0.004), centrum semiovale (mean ± SD 825 ± 42 ms; p < 0.001) and contralateral white matter (mean ± SD 799 ± 40 ms; p < 0.001). MRF T2 relaxation times were longer for meningioma (mean ± SD 69 ± 27 ms) as compared to thalamus (mean ± SD 27 ± 3 ms; p < 0.001), caudate head (mean ± SD 39 ± 5 ms; p < 0.001) and contralateral white matter (mean ± SD 35 ± 4 ms; p < 0.001) Conclusions Phantom measurements indicate that the proposed 3D-MRF sequence relaxometry estimations are valid and reproducible. For in vivo, entire brain coverage was obtained in clinically feasible time and allows quantitative assessment of meningioma in clinical practice.

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The role of cochlear implant positioning on MR imaging quality: a preclinical in vivo study with a novel implant magnet system

European Archives of Oto-Rhino-Laryngology ◽

10.1007/s00405-021-07005-y ◽

2021 ◽

Author(s):

Pietro Canzi ◽

Marianna Magnetto ◽

Anna Simoncelli ◽

Marco Manfrin ◽

Federico Aprile ◽

...

Keyword(s):

Mr Imaging ◽

Cochlear Implant ◽

Occipital Lobe ◽

Brain Structures ◽

Magnet System ◽

High Positive Correlation ◽

Imaging Quality ◽

Signal Void ◽

Mri Surveillance

Abstract Purposes To investigate the effects for Ultra 3D cochlear implant (CI) positioning on MR imaging quality, looking at a comprehensive description of intracranial structures in cases of unilateral and bilateral CI placement. Methods Four CI angular positions (90°, 120°, 135° and 160°) at 9 cm distance from the outer-ear canal were explored. The 1.5 T MRI assessment included our institutional protocol for the investigation of brain pathologies without gadolinium application. Three investigators (two experienced neuroradiologists and one experienced otoneurosurgeon) independently evaluated the MR findings. A 4-point scale was adopted to describe 14 intracranial structures and to determine which CI positioning allowed the best image quality score and how bilateral CI placement modified MRI scan visibility. Results A high positive correlation was found between the three blinded observers. Structures situated contralateral from the CI showed high-quality values in all four placements. Structures situated ipsilaterally provided results suitable for diagnostic purposes for at least one position. At 90°, artifacts mainly involved brain structures located cranially and anteriorly (e.g., temporal lobe); on the contrary, at 160°, artifacts mostly influenced the posterior fossa structures (e.g., occipital lobe). For the bilateral CI condition, MR imaging examination revealed additional artifacts involving all structures located close to either CI, where there was a signal void/distortion area. Conclusions Suitable unilateral CI positioning can allow the visualization of intracranial structures with sufficient visibility for diagnostic purposes. Bilateral CI positioning significantly deteriorates the anatomical visibility. CI positioning might play a crucial role for patients who need post-operative MRI surveillance.

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