The Experts below are selected from a list of 60 Experts worldwide ranked by ideXlab platform

William E Butler - One of the best experts on this subject based on the ideXlab platform.

  • wavelet Brain Angiography suggests arteriovenous pulse wave phase locking
    PLOS ONE, 2017
    Co-Authors: William E Butler
    Abstract:

    When a stroke volume of arterial blood arrives to the Brain, the total blood volume in the bony cranium must remain constant as the proportions of arterial and venous blood vary, and by the end of the cardiac cycle an equivalent volume of venous blood must have been ejected. I hypothesize the Brain to support this process by an extraluminally mediated exchange of information between its arterial and venous circulations. To test this I introduce wavelet Angiography methods to resolve single moving vascular pulse waves (PWs) in the Brain while simultaneously measuring Brain pulse motion. The wavelet methods require angiographic data acquired at significantly faster rate than cardiac frequency. I obtained these data in humans from Brain surface optical angiograms at craniotomy and in piglets from ultrasound angiograms via cranial window. I exploit angiographic time of flight to resolve arterial from venous circulation. Initial wavelet reconstruction proved unsatisfactory because of angiographic motion alias from Brain pulse motion. Testing with numerically simulated cerebral angiograms enabled the development of a vascular PW cine imaging method based on cross-correlated wavelets of mixed high frequency and high temporal resolution respectively to attenuate frequency and motion alias. Applied to the human and piglet data, the method resolves individual arterial and venous PWs and finds them to be phase locked each with separate phase relations to Brain pulse motion. This is consistent with arterial and venous PW coordination mediated by pulse motion and points to a testable hypothesis of a function of cerebrospinal fluid in the ventricles of the Brain.

Pierre Lasjaunias - One of the best experts on this subject based on the ideXlab platform.

  • aneurysmal malformation of the vein of galen in three patients clinical and radiological follow up
    Neuroradiology, 1998
    Co-Authors: A Campi, Georges Rodesch, G Scotti, Pierre Lasjaunias
    Abstract:

    We studied three patients with aneurysmal malformations of the vein of Galen: all underwent embolisation followed by MRI and conventional Angiography; two also underwent postembolisation magnetic resonance Angiography (MRA). MRI was performed before treatment in two patients, MRA in only one, diagnosed prenatally. Two patients had normal appearances on follow-up MR studies and were completely cured by embolisation. However, the last patient, after two embolisations, despite the stabilisation of the clinical condition, underwent surgery and died. We think MRI is mandatory before endoarterial treatment, to assess the conditions of the Brain. Angiography is mandatory only at the time of endovascular treatment, while MRA and MRI have a role in follow-up. Endoarterial embolisation remains the treatment of choice, and surgery is not advisable.

Jun Qian - One of the best experts on this subject based on the ideXlab platform.

  • aggregation induced emission nanoparticles for in vivo three photon fluorescence microscopic rat Brain Angiography
    Journal of Innovative Optical Health Sciences, 2019
    Co-Authors: Hequn Zhang, Weisi Xie, Ming Chen, Liang Zhu, Zhe Feng, Yalun Wang, Ben Zhong Tang, Jun Qian
    Abstract:

    Rodents are popular biological models for physiological and behavioral research in neuroscience and rats are better models than mice due to their higher genome similarity to human and more accessib...

  • fluorescence resonance energy transfer fret based nanoparticles composed of aie luminogens and nir dyes with enhanced three photon near infrared emission for in vivo Brain Angiography
    Nanoscale, 2018
    Co-Authors: Wen Liu, Liang Zhu, Yalun Wang, Xiao Han, Chaowei Sun, Jun Qian
    Abstract:

    Near-infrared (NIR) fluorescence is very important for high-contrast biological imaging of high-scattering tissues such as Brain tissue. Unfortunately, commercial NIR dyes are excited usually by visible light, and their multi-photon absorption (MPA) cross-sections are small. Here, we design new co-encapsulated NIR nanoparticles (NPs) with a large three-photon (3PA) absorption cross-section. A form of aggregation-induced emission (AIE) luminogen (AIEgen), 2,3-bis(4'-(diphenylamino)-[1,1'-biphenyl]-4-yl) fumaronitrile (TPATCN), is introduced as the donor, and a form of NIR dye, silicon 2,3-naphthalocyanine bis-(trihexylsilyloxide) (NIR775), is adopted as the acceptor. Under the excitation of a 1550 nm fs laser, TPATCN-NIR775 NPs demonstrated a bright three-photon fluorescence centered at 785 nm. The energy transfer efficiency of the TPATCN-NIR775 NPs was calculated to be as high as 90%, which could be attributed to the good spectral overlap between the emission of TPATCN and the absorption of NIR775. By injection with TPATCN-NIR775 NPs, a vivid 3D reconstruction of mouse Brain vasculature was obtained with even small blood vessels clearly visualized. The design strategy used for the co-encapsulated AIE-NIR NPs would be helpful in synthesizing more NIR probes for deep-tissue biological imaging in the future.

  • bright aie nanoparticles with f127 encapsulation for deep tissue three photon intravital Brain Angiography
    Advanced Healthcare Materials, 2017
    Co-Authors: Yalun Wang, Xiao Han, Anna W Roe, Jun Qian
    Abstract:

    Deep-tissue imaging is of great significance to biological applications. In this paper, a deep-red emissive luminogen 2,3-bis(4'-(diphenylamino)-[1,1'-biphenyl]-4-yl) fumaronitrile (TPATCN) with aggregation-induced emission (AIE) feature is prepared. TPATCN molecules were then encapsulated within a polymeric matrix of Pluronic F-127 to form nanoparticles (NPs). TPATCN NPs exhibit bright three-photon fluorescence (3PF) in deep-red region, together with high chemical stability, good photostability, and biocompatibility. They are further utilized for in vivo 3PF imaging of the Brain vasculature of mice, under the excitation of a 1550 nm femtosecond laser. A vivid 3D reconstruction of the Brain vasculature is then built with a penetration depth of 875 µm, which is the largest in ever reported 3PF imaging based on AIE NPs. After that, by collecting both of the 3PF and third-harmonic generation signals, multichannel nonlinear optical imaging of the Brain blood vessels is further realized. These results will be helpful to study the structures and functions of the Brain in the future.

Stephen J Riederer - One of the best experts on this subject based on the ideXlab platform.

  • 3d high temporal and spatial resolution contrast enhanced mr Angiography of the whole Brain
    Magnetic Resonance in Medicine, 2008
    Co-Authors: Clifton R Haider, Norbert G Campeau, John Huston, Stephen J Riederer
    Abstract:

    Sensitivity encoding (SENSE) and partial Fourier techniques have been shown to reduce the acquisition time and provide high diagnostic image quality. However, for time-resolved acquisitions there is a need for both high temporal and spatial resolution. View sharing can be used to provide an increased frame rate but at the cost of acquiring spatial frequencies over a duration longer than a frame time. In this work, we hypothesize that a CArtesian Projection Reconstruction-like (CAPR) technique in combination with 2D SENSE, partial Fourier, and view sharing can provide 1 to 2 mm isotropic resolution with sufficient temporal resolution to distinguish intracranial arterial and venous phases of contrast passage in whole-Brain Angiography. In doing so, the parameter of "temporal footprint" is introduced as a descriptor for characterizing and comparing time-resolved view-shared pulse sequences. It is further hypothesized that short temporal footprint sequences have higher temporal fidelity than similar sequences with longer temporal footprints. The tradeoff of temporal footprint and temporal acceleration is presented and characterized in numerical simulations. Results from 11 whole-Brain CE-MRA studies with the new method with SENSE acceleration factors R = 4 and 5.3 are shown to provide images of comparable or higher diagnostic quality than the unaccelerated reference.

Motiei-langroudi Rouzbeh - One of the best experts on this subject based on the ideXlab platform.

  • Brain Computed Tomography Angiography as an Ancillary Test in the Confirmation of Brain Death
    'Cureus Inc.', 2017
    Co-Authors: Sadeghian Homa, Raeisi, Mohammad Ali, Dolati Parviz, Motiei-langroudi Rouzbeh
    Abstract:

    Introduction: Brain death (BD) is the irreversible termination of the functioning of the Brain. The diagnosis should be first made by clinical criteria and confirmed by using paraclinical confirmatory techniques (ancillary tests). While conventional Brain Angiography remains the standard method of choice, computed tomography Angiography (CTA) has emerged as an alternative method. In this study, we tried to evaluate the accuracy of CTA for the diagnosis of BD. Methods: In this study, we included nine patients with a clinical diagnosis of BD, confirmed by electroencephalography (EEG). CTA was then performed to compare the results. Results: The most frequent cause for BD was multiple trauma (7/9) in our patients, followed by aneurysm rupture and Brain infarct. CTA examination in all patients showed opacification of extracranial arteries and major branches of external carotid artery (ECA), including superficial temporal arteries (STAs), while no opacification was observed in the internal carotid arteries (ICA) including and beyond the cavernous segment, middle cerebral arteries (MCAs), anterior cerebral arteries (ACAs), distal vertebral arteries (VAs), and basilar artery (BA). Moreover, no opacification was observed in the internal cerebral veins (ICVs) or great cerebral vein (GCV). Conclusion: The accuracy rate of CTA in the detection of intracranial circulatory arrest was 100%. CTA examinations confirmed BD diagnoses in all patients who had clinical and EEG BD diagnoses, and no confliction between CTA findings and clinical diagnoses was observed