scholarly journals 4D flow MRI for non-invasive measurement of blood flow in the brain: A systematic review

2020 ◽  
pp. 0271678X2095201
Author(s):  
Alasdair G Morgan ◽  
Michael J Thrippleton ◽  
Joanna M Wardlaw ◽  
Ian Marshall
Keyword(s):  
Blood Flow ◽  
Imaging Techniques ◽  
Acquisition Time ◽  
4D Flow ◽  
Non Invasive ◽  
Major Vessel ◽  
Dynamic Velocity ◽  
Blood Flow Dynamics ◽  
Cerebrovascular Imaging

The brain’s vasculature is essential for brain health and its dysfunction contributes to the onset and development of many dementias and neurological disorders. While numerous in vivo imaging techniques exist to investigate cerebral haemodynamics in humans, phase-contrast magnetic resonance imaging (MRI) has emerged as a reliable, non-invasive method of quantifying blood flow within intracranial vessels. In recent years, an advanced form of this method, known as 4D flow, has been developed and utilised in patient studies, where its ability to capture complex blood flow dynamics within any major vessel across the acquired volume has proved effective in collecting large amounts of information in a single scan. While extremely promising as a method of examining the vascular system’s role in brain-related diseases, the collection of 4D data can be time-consuming, meaning data quality has to be traded off against the acquisition time. Here, we review the available literature to examine 4D flow’s capabilities in assessing physiological and pathological features of the cerebrovascular system. Emerging techniques such as dynamic velocity-encoding and advanced undersampling methods, combined with increasingly high-field MRI scanners, are likely to bring 4D flow to the forefront of cerebrovascular imaging studies in the years to come.

Integration Between Computed Tomography and Nuclear Medicine for Non-invasive Assessment of Coronary Anatomy and Myocardial Perfusion

2009 ◽  
Vol 5 (2) ◽  
pp. 15
Author(s):  
Wanda Acampa ◽  
Mario Petretta ◽  
Carmela Nappi ◽  
Alberto Cuocolo ◽  
◽  
...  
Keyword(s):  
Computed Tomography ◽  
Coronary Heart Disease ◽  
Blood Flow ◽  
Heart Disease ◽  
Myocardial Perfusion ◽  
Myocardial Blood Flow ◽  
Imaging Techniques ◽  
Emission Computed Tomography ◽  
Coronary Anatomy ◽  
Non Invasive

Many non-invasive imaging techniques are available for the evaluation of patients with known or suspected coronary heart disease. Among these, computed-tomography-based techniques allow the quantification of coronary atherosclerotic calcium and non-invasive imaging of coronary arteries, whereas nuclear cardiology is the most widely used non-invasive approach for the assessment of myocardial perfusion. The available single-photon-emission computed tomography flow agents are characterised by a cardiac uptake proportional to myocardial blood flow. In addition, different positron emission tomography tracers may be used for the quantitative measurement of myocardial blood flow and coronary flow reserve. Extensive research is being performed in the development of non-invasive coronary angiography and myocardial perfusion imaging using cardiac magnetic resonance. Finally, new multimodality imaging systems have recently been developed bringing together anatomical and functional information. This article provides a description of the available non-invasive imaging techniques in the assessment of coronary anatomy and myocardial perfusion in patients with known or suspected coronary heart disease.

scholarly journals In Vivo Imaging of Biodegradable Implants and Related Tissue Biomarkers

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2348
Author(s):  
Leon Riehakainen ◽  
Chiara Cavallini ◽  
Paolo Armanetti ◽  
Daniele Panetta ◽  
Davide Caramella ◽  
...  
Keyword(s):  
Imaging Modality ◽  
Imaging Techniques ◽  
Special Focus ◽  
Tissue Remodelling ◽  
Biodegradable Implant ◽  
Advantages And Disadvantages ◽  
Non Invasive ◽  
Positron Emission ◽  
Longitudinal Imaging

Non-invasive longitudinal imaging of osseointegration of bone implants is essential to ensure a comprehensive, physical and biochemical understanding of the processes related to a successful implant integration and its long-term clinical outcome. This study critically reviews the present imaging techniques that may play a role to assess the initial stability, bone quality and quantity, associated tissue remodelling dependent on implanted material, implantation site (surrounding tissues and placement depth), and biomarkers that may be targeted. An updated list of biodegradable implant materials that have been reported in the literature, from metal, polymer and ceramic categories, is provided with reference to the use of specific imaging modalities (computed tomography, positron emission tomography, ultrasound, photoacoustic and magnetic resonance imaging) suitable for longitudinal and non-invasive imaging in humans. The advantages and disadvantages of the single imaging modality are discussed with a special focus on preclinical imaging for biodegradable implant research. Indeed, the investigation of a new implant commonly requires histological examination, which is invasive and does not allow longitudinal studies, thus requiring a large number of animals for preclinical testing. For this reason, an update of the multimodal and multi-parametric imaging capabilities will be here presented with a specific focus on modern biomaterial research.

scholarly journals Study of Osteocyte Behavior by High-Resolution Intravital Imaging Following Photo-Induced Ischemia

Molecules ◽  
2018 ◽  
Vol 23 (11) ◽  
pp. 2874
Author(s):  
Hengfeng Yuan ◽  
Wen Jiang ◽  
Yuanxin Chen ◽  
Betty Kim
Keyword(s):  
Imaging Techniques ◽  
Avascular Osteonecrosis ◽  
Functional Changes ◽  
Cellular Processes ◽  
Non Invasive ◽  
Behavioral Dynamics ◽  
Bony Anatomy ◽  
Magnetic Resonance Imaging Mri

Ischemic injuries and local hypoxia can result in osteocytes dysfunction and play a key role in the pathogenesis of avascular osteonecrosis. Conventional imaging techniques including magnetic resonance imaging (MRI) and computed tomography (CT) can reveal structural and functional changes within bony anatomy; however, characterization of osteocyte behavioral dynamics in the setting of osteonecrosis at the single cell resolution is limited. Here, we demonstrate an optical approach to study real-time osteocyte functions in vivo. Using nicotinamide adenine dinucleotide (NADH) as a biomarker for metabolic dynamics in osteocytes, we showed that NADH level within osteocytes transiently increase significantly after local ischemia through non-invasive photo-induced thrombosis of afferent arterioles followed by a steady decline. Our study presents a non-invasive optical approach to study osteocyte behavior through the modulation of local environmental conditions. Thus it provides a powerful toolkit to study cellular processes involved in bone pathologies in vivo.

scholarly journals 1050: Cross-modality, in-vivo validation of 4D-Flow MRI evaluation of uterine artery blood flow in human pregnancy

2019 ◽  
Vol 220 (1) ◽  
pp. S673-S674
Author(s):  
Nadav Schwartz ◽  
Eileen Hwuang ◽  
Ana Rodriguez-Soto ◽  
Felix Wehrli ◽  
Marta Vidorreta ◽  
...  
Keyword(s):  
Blood Flow ◽  
Uterine Artery ◽  
Artery Blood Flow ◽  
4D Flow Mri ◽  
4D Flow ◽  
Human Pregnancy ◽  
Flow Mri ◽  
Mri Evaluation ◽  
In Vivo Validation

scholarly journals Microcirculatory model predicts blood flow and autoregulation range in the human retina: in vivo investigation with laser speckle flowgraphy

2020 ◽  
Vol 319 (6) ◽  
pp. H1253-H1273
Author(s):  
Konstantinos Pappelis ◽  
Lars Choritz ◽  
Nomdo M. Jansonius
Keyword(s):  
Blood Flow ◽  
Healthy Subjects ◽  
Imaging Techniques ◽  
Physiological Model ◽  
Laser Speckle ◽  
Retinal Blood Flow ◽  
Laser Speckle Flowgraphy ◽  
New Approach ◽  
Pressure Drops

We describe and test a new approach to quantify retinal blood flow, based on standard clinical examinations and imaging techniques, linked together with a physiological model. We use these findings to generate individualized estimates of the autoregulation range. We provide evidence that healthy subjects are closer to the lower autoregulation limit than thought before. This suggests that some retinas are less prepared to withstand hypoperfusion, even after small intraocular pressure rises or blood pressure drops.

scholarly journals Non-Invasive Assessment of Intravascular Pressure Gradients: A Review of Current and Proposed Novel Methods

Diagnostics ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 5 ◽  
Author(s):  
Tin-Quoc Nguyen ◽  
Kristoffer Hansen ◽  
Thor Bechsgaard ◽  
Lars Lönn ◽  
Jørgen Jensen ◽  
...  
Keyword(s):  
Stokes Equations ◽  
Imaging Techniques ◽  
Navier Stokes ◽  
Pressure Gradients ◽  
Bernoulli Equation ◽  
Strong Correlations ◽  
Navier Stokes Equations ◽  
Non Invasive ◽  
Invasive Techniques

Invasive catheterization is associated with a low risk of serious complications. However, although it is the gold standard for measuring pressure gradients, it induces changes to blood flow and requires significant resources. Therefore, non-invasive alternatives are urgently needed. Pressure gradients are routinely estimated non-invasively in clinical settings using ultrasound and calculated with the simplified Bernoulli equation, a method with several limitations. A PubMed literature search on validation of non-invasive techniques was conducted, and studies were included if non-invasively estimated pressure gradients were compared with invasively measured pressure gradients in vivo. Pressure gradients were mainly estimated from velocities obtained with Doppler ultrasound or magnetic resonance imaging. Most studies used the simplified Bernoulli equation, but more recent studies have employed the expanded Bernoulli and Navier–Stokes equations. Overall, the studies reported good correlation between non-invasive estimation of pressure gradients and catheterization. Despite having strong correlations, several studies reported the non-invasive techniques to either overestimate or underestimate the invasive measurements, thus questioning the accuracy of the non-invasive methods. In conclusion, more advanced imaging techniques may be needed to overcome the shortcomings of current methods.

Non-invasive pulmonary blood flow analysis and blood pressure mapping derived from 4D flow MRI

2015 ◽  
Author(s):  
Michael Delles ◽  
Fabian Rengier ◽  
Yoo-Jin Azad ◽  
Sebastian Bodenstedt ◽  
Hendrik von Tengg-Kobligk ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Flow Analysis ◽  
4D Flow Mri ◽  
4D Flow ◽  
Non Invasive ◽  
Pressure Mapping ◽  
Flow Mri ◽  
Blood Flow Analysis

Monitoring of Blood Flow by Drug Stimulation on Mouse Brain Using Non-Invasive Photoacoustic Imaging Technology

2007 ◽  
Vol 364-366 ◽  
pp. 1123-1127
Author(s):  
Shi Hua Yang ◽  
Ye Qi Lao
Keyword(s):  
Blood Flow ◽  
Mouse Brain ◽  
Light Absorption ◽  
Brain Function ◽  
Photoacoustic Imaging ◽  
Non Invasive ◽  
Mouse Cerebral Cortex ◽  
Flow Changes ◽  
The Brain

The highlight of photoacosutic imaging (PAI) is a method that combines ultrasonic resolution with high contrast due to light absorption. Photoacoustic signals carry the information of the light absorption distribution of biological tissue, which is often related to its character of structure, physiological and pathological changes because of different physiology conditions in response to different light absorption coefficients. A non-invasive PAI system was developed and successfully acquired in vivo images of mouse brain. Based on the intrinsic PA signals from the brain, the vascular network and the detailed structures of the mouse cerebral cortex were clearly visualized. The ability of PAI monitoring of cerebral hemodynamics was also demonstrated by mapping of the mouse superficial cortex with and without drug stimulation. The extracted PA signals intensity profiles obviously testified that the cerebral blood flow (CBF) in the mouse brain was changed under the stimulation of acetazolamide (ACZ). The experimental results suggest that PAI can provide non-invasive images of blood flow changes, and has the potential for brain function detection.

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