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Liu TT, Wong EC, Bolar DS, Chen C, Barnes RS. A mathematical model for velocity-selective arterial spin labeling. Magn Reson Med 2024; 91:1384-1403. [PMID: 38181170 DOI: 10.1002/mrm.29935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 10/04/2023] [Accepted: 11/03/2023] [Indexed: 01/07/2024]
Abstract
PURPOSE To present a theoretical framework that rigorously defines and analyzes key concepts and quantities for velocity selective arterial spin labeling (VSASL). THEORY AND METHODS An expression for the VSASL arterial delivery function is derived based on (1) labeling and saturation profiles as a function of velocity and (2) physiologically plausible approximations of changes in acceleration and velocity across the vascular system. The dependence of labeling efficiency on the amplitude and effective bolus width of the arterial delivery function is defined. Factors that affect the effective bolus width are examined, and timing requirements to minimize quantitation errors are derived. RESULTS The model predicts that a flow-dependent negative bias in the effective bolus width can occur when velocity selective inversion (VSI) is used for the labeling module and velocity selective saturation (VSS) is used for the vascular crushing module. The bias can be minimized by choosing a nominal labeling cutoff velocity that is lower than the nominal cutoff velocity of the vascular crushing module. CONCLUSION The elements of the model are specified in a general fashion such that future advances can be readily integrated. The model can facilitate further efforts to understand and characterize the performance of VSASL and provide critical theoretical insights that can be used to design future experiments and develop novel VSASL approaches.
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Affiliation(s)
- Thomas T Liu
- Center for Functional MRI, University of California San Diego, La Jolla, California, USA
- Department of Radiology, University of California San Diego, La Jolla, California, USA
- Department of Psychiatry, University of California San Diego, La Jolla, California, USA
| | - Eric C Wong
- Center for Functional MRI, University of California San Diego, La Jolla, California, USA
- Department of Radiology, University of California San Diego, La Jolla, California, USA
- Department of Psychiatry, University of California San Diego, La Jolla, California, USA
| | - Divya S Bolar
- Center for Functional MRI, University of California San Diego, La Jolla, California, USA
- Department of Radiology, University of California San Diego, La Jolla, California, USA
| | - Conan Chen
- Center for Functional MRI, University of California San Diego, La Jolla, California, USA
- Department of Radiology, University of California San Diego, La Jolla, California, USA
- Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California, USA
| | - Ryan S Barnes
- Center for Functional MRI, University of California San Diego, La Jolla, California, USA
- Department of Radiology, University of California San Diego, La Jolla, California, USA
- Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California, USA
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2
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Daher A, Payne S. The conducted vascular response as a mediator of hypercapnic cerebrovascular reactivity: A modelling study. Comput Biol Med 2024; 170:107985. [PMID: 38245966 DOI: 10.1016/j.compbiomed.2024.107985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 12/29/2023] [Accepted: 01/13/2024] [Indexed: 01/23/2024]
Abstract
It is well established that the cerebral blood flow (CBF) shows exquisite sensitivity to changes in the arterial blood partial pressure of CO2 ( [Formula: see text] ), which is reflected by an index termed cerebrovascular reactivity. In response to elevations in [Formula: see text] (hypercapnia), the vessels of the cerebral microvasculature dilate, thereby decreasing the vascular resistance and increasing CBF. Due to the challenges of access, scale and complexity encountered when studying the microvasculature, however, the mechanisms behind cerebrovascular reactivity are not fully understood. Experiments have previously established that the cholinergic release of the Acetylcholine (ACh) neurotransmitter in the cortex is a prerequisite for the hypercapnic response. It is also known that ACh functions as an endothelial-dependent agonist, in which the local administration of ACh elicits local hyperpolarization in the vascular wall; this hyperpolarization signal is then propagated upstream the vascular network through the endothelial layer and is coupled to a vasodilatory response in the vascular smooth muscle (VSM) layer in what is known as the conducted vascular response (CVR). Finally, experimental data indicate that the hypercapnic response is more strongly correlated with the CO2 levels in the tissue than in the arterioles. Accordingly, we hypothesize that the CVR, evoked by increases in local tissue CO2 levels and a subsequent local release of ACh, is responsible for the CBF increase observed in response to elevations in [Formula: see text] . By constructing physiologically grounded dynamic models of CBF and control in the cerebral vasculature, ones that integrate the available knowledge and experimental data, we build a new model of the series of signalling events and pathways underpinning the hypercapnic response, and use the model to provide compelling evidence that corroborates the aforementioned hypothesis. If the CVR indeed acts as a mediator of the hypercapnic response, the proposed mechanism would provide an important addition to our understanding of the repertoire of metabolic feedback mechanisms possessed by the brain and would motivate further in-vivo investigation. We also model the interaction of the hypercapnic response with dynamic cerebral autoregulation (dCA), the collection of mechanisms that the brain possesses to maintain near constant CBF despite perturbations in pressure, and show how the dCA mechanisms, which otherwise tend to be overlooked when analysing experimental results of cerebrovascular reactivity, could play a significant role in shaping the CBF response to elevations in [Formula: see text] . Such in-silico models can be used in tandem with in-vivo experiments to expand our understanding of cerebrovascular diseases, which continue to be among the leading causes of morbidity and mortality in humans.
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Affiliation(s)
- Ali Daher
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, United Kingdom.
| | - Stephen Payne
- Institute of Applied Mechanics, National Taiwan University, Taiwan
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3
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Lalou AD, Czosnyka ZH, Czosnyka M. Observational study of intracranial pressure instability in patients with pseudotumour cerebri syndrome. BRAIN & SPINE 2024; 4:102758. [PMID: 38510634 PMCID: PMC10951771 DOI: 10.1016/j.bas.2024.102758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 01/15/2024] [Accepted: 01/21/2024] [Indexed: 03/22/2024]
Abstract
Introduction A fixed CSF pressure (CSFp) of 25 cmH2O (18 mmHg) has been utilised to date to define and classify pseudotumour cerebri syndrome (PTCS). Furthermore, ICP monitoring, and CSF infusion tests have not been frequently performed in this group of patients. Research question We aimed to report typical, unusual and unstable patterns of ICP in patients with PTCS. Material and methods We reviewed the recordings of CSF infusion tests and overnight ICP monitoring of patients with suspected or confirmed IIH between January 2003-December 2020.We excluded all patients with a shunt in situ and selected recordings that represented unstable patterns of ICP changes in PTCS. Results 463 CSF infusion tests and 26 ICP monitorings of PTCS patients had been performed in this timeframe. We divided results of observed pattern into two group: those with known venous sinus measurements (Group A) and those without (Group B). Observed recordings formed a total of 5 and 4 different patterns respectively, based on the behaviour of ICP and slow waves at rest, overnight, and during infusion as well as in relationship to the clinical presentation of each patient. Discussion and conclusion Accurate monitoring of ICP in PTCS is quintessential. Full understanding of each element of its pathophysiology and their interaction would be essential and include quantification of the CSF pressure not only as a number, but also with consideration of its dynamic contents. Cerebral venous pressure measurements and/or monitoring may be useful. Consideration of the presence or absence of papilloedema in the context of disturbed CSF dynamics could reveal further diagnostic and therapeutic insights.
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Affiliation(s)
- Afroditi D. Lalou
- Department of Clinical Neurosciences, Division of Neurosurgery, Brain Physics Laboratory, University of Cambridge & Cambridge University Hospital NHS Foundation Trust, United Kingdom
- Department of Neurology, King's College Hospital NHS Foundation Trust, London, United Kingdom
- Department of Radiation Sciences, Faculty of Medicine, Umeå University, Umeå, Sweden
| | - Zofia H. Czosnyka
- Department of Clinical Neurosciences, Division of Neurosurgery, Brain Physics Laboratory, University of Cambridge & Cambridge University Hospital NHS Foundation Trust, United Kingdom
| | - Marek Czosnyka
- Department of Clinical Neurosciences, Division of Neurosurgery, Brain Physics Laboratory, University of Cambridge & Cambridge University Hospital NHS Foundation Trust, United Kingdom
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Goudot G, Jimenez A, Mohamedi N, Sitruk J, Khider L, Mortelette H, Papadacci C, Hyafil F, Tanter M, Messas E, Pernot M, Mirault T. Assessment of Takayasu's arteritis activity by ultrasound localization microscopy. EBioMedicine 2023; 90:104502. [PMID: 36893585 PMCID: PMC10017361 DOI: 10.1016/j.ebiom.2023.104502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 02/10/2023] [Accepted: 02/10/2023] [Indexed: 03/09/2023] Open
Abstract
BACKGROUND Ultrasound localization microscopy (ULM) based on ultrafast ultrasound imaging of circulating microbubbles (MB) can image microvascular blood flows in vivo up to the micron scale. Takayasu arteritis (TA) has an increased vascularisation of the thickened arterial wall when active. We aimed to perform vasa vasorum ULM of the carotid wall and demonstrate that ULM can provide imaging markers to assess the TA activity. METHODS Patients with TA were consecutively included with assessment of activity by the National Institute of Health criteria: 5 had active TA (median age 35.8 [24.5-46.0] years) and 11 had quiescent TA (37.2 [31.7-47.3] years). ULM was performed using a 6.4 MHz probe and a dedicated imaging sequence (plane waves with 8 angles, frame rate 500 Hz), coupled with the intravenous injection of MB. Individual MB were localised at a subwavelength scale then tracked, allowing the reconstruction of the vasa vasorum flow anatomy and velocity. FINDINGS ULM allowed to show microvessels and to measure their flow velocity within the arterial wall. The number of MB detected per second in the wall was 121 [80-146] in active cases vs. 10 [6-15] in quiescent cases (p = 0.0005), with a mean velocity of 40.5 [39.0-42.9] mm.s-1 in active cases. INTERPRETATION ULM allows visualisation of microvessels within the thickened carotid wall in TA, with significantly greater MB density in active cases. ULM provides a precise visualisation in vivo of the vasa vasorum and gives access to the arterial wall vascularisation quantification. FUNDING French Society of Cardiology. ART (Technological Research Accelerator) biomedical ultrasound program of INSERM, France.
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Affiliation(s)
- Guillaume Goudot
- Vascular Medicine Department, Georges Pompidou European Hospital, APHP, Paris, France; Université Paris Cité, INSERM U970 PARCC, F-75015 Paris, France.
| | - Anatole Jimenez
- Physics for Medicine Paris, INSERM U1273, ESPCI Paris, CNRS UMR 8631, PSL Research University, Paris, France
| | - Nassim Mohamedi
- Vascular Medicine Department, Georges Pompidou European Hospital, APHP, Paris, France; Université Paris Cité, INSERM U970 PARCC, F-75015 Paris, France
| | - Jonas Sitruk
- Vascular Medicine Department, Georges Pompidou European Hospital, APHP, Paris, France; Université Paris Cité, INSERM U970 PARCC, F-75015 Paris, France
| | - Lina Khider
- Vascular Medicine Department, Georges Pompidou European Hospital, APHP, Paris, France; Université Paris Cité, INSERM U970 PARCC, F-75015 Paris, France
| | - Hélène Mortelette
- Vascular Medicine Department, Georges Pompidou European Hospital, APHP, Paris, France
| | - Clément Papadacci
- Physics for Medicine Paris, INSERM U1273, ESPCI Paris, CNRS UMR 8631, PSL Research University, Paris, France
| | - Fabien Hyafil
- Nuclear Medicine Department, Georges Pompidou European Hospital, APHP, Université Paris Cité, Paris, France
| | - Mickaël Tanter
- Physics for Medicine Paris, INSERM U1273, ESPCI Paris, CNRS UMR 8631, PSL Research University, Paris, France
| | - Emmanuel Messas
- Vascular Medicine Department, Georges Pompidou European Hospital, APHP, Paris, France; Université Paris Cité, INSERM U970 PARCC, F-75015 Paris, France
| | - Mathieu Pernot
- Physics for Medicine Paris, INSERM U1273, ESPCI Paris, CNRS UMR 8631, PSL Research University, Paris, France
| | - Tristan Mirault
- Vascular Medicine Department, Georges Pompidou European Hospital, APHP, Paris, France; Université Paris Cité, INSERM U970 PARCC, F-75015 Paris, France; French National Reference Centre for Rare Vascular Diseases, FAVA-MULTI, Member of the European Reference Network on Rare Multisystemic Vascular Diseases (VASCERN), F-75015 Paris, France
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5
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Kovtanyuk A, Turova V, Sidorenko I, Chebotarev A, Lampe R. Modeling of the cerebral blood circulation in a capillary network accounting for the influence of the endothelial surface layer. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 224:107008. [PMID: 35901640 DOI: 10.1016/j.cmpb.2022.107008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 06/22/2022] [Accepted: 07/05/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND AND OBJECTIVE The paper describes a mathematical model of blood flow in capillaries with accounting for the endothelial surface layer (ESL). METHOD The influence of ESL is modeled by a boundary layer with zero flow velocity. Finite element modeling and an analytical approach based on the homogenization of the core region of blood flow occupied by erythrocytes are developed to describe the resistance of a capillary. The reliability of the results obtained is verified for different values of the discharge hematocrit and vessel diameter using known in vivo data. RESULTS The proposed approach is applied to the numerical simulation of blood circulation in a capillary network of the germinal matrix of infants born at 25 gestational weeks. The influence of the hematocrit level and effective thickness of ESL on the resistance of the capillary network of the germinal matrix of preterm infants is studied. It was found that a decrease in the effective thickness of ESL in the capillary network (and/or a decrease in the hematocrit) leads to reducing the resistance of the capillary network. CONCLUSION A decrease in the effective thickness of ESL in the capillary network leads to an increase in the pressure drop in arterioles, which may be considered as an additional risk factor for hemorrhages in fragile blood vessels within the germinal matrix.
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Affiliation(s)
- Andrey Kovtanyuk
- Klinikum rechts der Isar, Technische Universität München, Ismaningerstr. 22, München, 81675, Germany.
| | - Varvara Turova
- Klinikum rechts der Isar, Technische Universität München, Ismaningerstr. 22, München, 81675, Germany.
| | - Irina Sidorenko
- Fakultät für Mathematik, Technische Universität München, Boltzmannstr. 3, Garching bei München, 85747, Germany.
| | - Alexander Chebotarev
- Far Eastern Federal University, Far Eastern Center for Research and Education in Mathematics, Ajax Bay 10, Russky Island, Vladivostok, 690922, Russia.
| | - Renée Lampe
- Klinikum rechts der Isar, Technische Universität München, Ismaningerstr. 22, München, 81675, Germany.
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6
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A novel computational model for cerebral blood flow rate control mechanisms to evaluate physiological cases. Biomed Signal Process Control 2022. [DOI: 10.1016/j.bspc.2022.103851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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7
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Functional ultrasound localization microscopy reveals brain-wide neurovascular activity on a microscopic scale. Nat Methods 2022; 19:1004-1012. [PMID: 35927475 PMCID: PMC9352591 DOI: 10.1038/s41592-022-01549-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 06/14/2022] [Indexed: 12/02/2022]
Abstract
The advent of neuroimaging has increased our understanding of brain function. While most brain-wide functional imaging modalities exploit neurovascular coupling to map brain activity at millimeter resolutions, the recording of functional responses at microscopic scale in mammals remains the privilege of invasive electrophysiological or optical approaches, but is mostly restricted to either the cortical surface or the vicinity of implanted sensors. Ultrasound localization microscopy (ULM) has achieved transcranial imaging of cerebrovascular flow, up to micrometre scales, by localizing intravenously injected microbubbles; however, the long acquisition time required to detect microbubbles within microscopic vessels has so far restricted ULM application mainly to microvasculature structural imaging. Here we show how ULM can be modified to quantify functional hyperemia dynamically during brain activation reaching a 6.5-µm spatial and 1-s temporal resolution in deep regions of the rat brain. Functional ultrasound localization microscopy monitors cerebrovascular blood flow by detecting the flow of injected microbubbles, providing access to brain activity at high spatiotemporal resolution.
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8
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Li W, Xu F, Zhu D, van Zijl PCM, Qin Q. T 2 -oximetry-based cerebral venous oxygenation mapping using Fourier-transform-based velocity-selective pulse trains. Magn Reson Med 2022; 88:1292-1302. [PMID: 35608208 PMCID: PMC9247032 DOI: 10.1002/mrm.29300] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 04/19/2022] [Accepted: 04/20/2022] [Indexed: 12/14/2022]
Abstract
Purpose To develop a T2‐oximetry method for quantitative mapping of cerebral venous oxygenation fraction (Yv) using Fourier‐transform–based velocity‐selective (FT‐VS) pulse trains. Methods The venous isolation preparation was achieved by using an FT‐VS inversion plus a nonselective inversion (NSI) pulse to null the arterial blood signal while minimally affected capillary blood flows out into the venular vasculature during the outflow time (TO), and then applying an Fourier transform based velocity selective saturation (FT‐VSS) pulse to suppress the tissue signal. A multi‐echo readout was employed to obtain venous T2 (T2,v) efficiently with the last echo used to detect the residual CSF signal and correct its contamination in the fitting. Here we compared the performance of this FT‐VS–based venous isolation preparations with a traditional velocity‐selective saturation (VSS)–based approach (quantitative imaging of extraction of oxygen and tissue consumption [QUIXOTIC]) with different cutoff velocities for Yv mapping on 6 healthy volunteers at 3 Tesla. Results The FT‐VS–based methods yielded higher venous blood signal and temporal SNR with less CSF contamination than the velocity‐selective saturation–based results. The averaged Yv values across the whole slice measured in different experiments were close to the global Yv measured from the individual internal jugular vein. Conclusion The feasibility of the FT‐VS–based Yv estimation was demonstrated on healthy volunteers. The obtained high venous signal as well as the mitigation of CSF contamination led to a good agreement between the T2,v and Yv measured in the proposed method with the values in the literature. Click here for author‐reader discussions
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Affiliation(s)
- Wenbo Li
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Feng Xu
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Dan Zhu
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Peter C M van Zijl
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Qin Qin
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
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9
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Intensity distribution segmentation in ultrafast Doppler combined with scanning laser confocal microscopy for assessing vascular changes associated with ageing in murine hippocampi. Sci Rep 2022; 12:6784. [PMID: 35473942 PMCID: PMC9042937 DOI: 10.1038/s41598-022-10457-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 04/06/2022] [Indexed: 11/21/2022] Open
Abstract
The hippocampus plays an important role in learning and memory, requiring high-neuronal oxygenation. Understanding the relationship between blood flow and vascular structure—and how it changes with ageing—is physiologically and anatomically relevant. Ultrafast Doppler (\documentclass[12pt]{minimal}
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\begin{document}$$\mu$$\end{document}μDoppler) and scanning laser confocal microscopy (SLCM) are powerful imaging modalities that can measure in vivo cerebral blood volume (CBV) and post mortem vascular structure, respectively. Here, we apply both imaging modalities to a cross-sectional and longitudinal study of hippocampi vasculature in wild-type mice brains. We introduce a segmentation of CBV distribution obtained from \documentclass[12pt]{minimal}
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\begin{document}$$\mu$$\end{document}μDoppler and show that this mice-independent and mesoscopic measurement is correlated with vessel volume fraction (VVF) distribution obtained from SLCM—e.g., high CBV relates to specific vessel locations with large VVF. Moreover, we find significant changes in CBV distribution and vasculature due to ageing (5 vs. 21 month-old mice), highlighting the sensitivity of our approach. Overall, we are able to associate CBV with vascular structure—and track its longitudinal changes—at the artery-vein, venules, arteriole, and capillary levels. We believe that this combined approach can be a powerful tool for studying other acute (e.g., brain injuries), progressive (e.g., neurodegeneration) or induced pathological changes.
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Réaux-Le-Goazigo A, Beliard B, Delay L, Rahal L, Claron J, Renaudin N, Rivals I, Thibaut M, Nouhoum M, Deffieux T, Tanter M, Pezet S. Ultrasound localization microscopy and functional ultrasound imaging reveal atypical features of the trigeminal ganglion vasculature. Commun Biol 2022; 5:330. [PMID: 35393515 PMCID: PMC8989975 DOI: 10.1038/s42003-022-03273-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 03/15/2022] [Indexed: 12/26/2022] Open
Abstract
The functional imaging within the trigeminal ganglion (TG) is highly challenging due to its small size and deep localization. This study combined a methodological framework able to dive into the rat trigeminal nociceptive system by jointly providing 1) imaging of the TG blood vasculature at microscopic resolution, and 2) the measurement of hemodynamic responses evoked by orofacial stimulations in anesthetized rats. Despite the small number of sensory neurons within the TG, functional ultrasound imaging was able to image and quantify a strong and highly localized hemodynamic response in the ipsilateral TG, evoked not only by mechanical or chemical stimulations of corneal nociceptive fibers, but also by cutaneous mechanical stimulations of the ophthalmic and maxillary orofacial regions using a von Frey hair. The in vivo quantitative imaging of the TG’s vasculature using ultrasound localization microscopy combined with in toto labelling reveals particular features of the vascularization of the area containing the sensory neurons, that are likely the origin of this strong vaso-trigeminal response. This innovative imaging approach opens the path for future studies on the mechanisms underlying changes in trigeminal local blood flow and evoked hemodynamic responses, key mechanisms for the understanding and treatment of debilitating trigeminal pain conditions. Visualisation of rat trigeminal ganglia activation during ophthalmic or maxillary nociceptive stimulations shows atypical tortuous vascularisation and a somatotopic hemodynamic response.
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Affiliation(s)
| | - Benoit Beliard
- Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research University, 17 rue Moreau, 75012, Paris, France
| | - Lauriane Delay
- Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research University, 17 rue Moreau, 75012, Paris, France
| | - Line Rahal
- Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research University, 17 rue Moreau, 75012, Paris, France
| | - Julien Claron
- Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research University, 17 rue Moreau, 75012, Paris, France
| | - Noémi Renaudin
- Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research University, 17 rue Moreau, 75012, Paris, France
| | - Isabelle Rivals
- Equipe de Statistique Appliquée, ESPCI Paris, PSL Research University, UMRS 1158, 10 rue Vauquelin, 75005, Paris, France
| | - Miguel Thibaut
- Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research University, 17 rue Moreau, 75012, Paris, France
| | - Mohamed Nouhoum
- Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research University, 17 rue Moreau, 75012, Paris, France.,Iconeus, 27 Rue du Faubourg Saint-Jacques, 75014, Paris, France
| | - Thomas Deffieux
- Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research University, 17 rue Moreau, 75012, Paris, France
| | - Mickael Tanter
- Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research University, 17 rue Moreau, 75012, Paris, France
| | - Sophie Pezet
- Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research University, 17 rue Moreau, 75012, Paris, France.
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11
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Zhang Z, Hwang M, Kilbaugh TJ, Sridharan A, Katz J. Cerebral microcirculation mapped by echo particle tracking velocimetry quantifies the intracranial pressure and detects ischemia. Nat Commun 2022; 13:666. [PMID: 35115552 PMCID: PMC8814032 DOI: 10.1038/s41467-022-28298-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 01/14/2022] [Indexed: 12/26/2022] Open
Abstract
Affecting 1.1‰ of infants, hydrocephalus involves abnormal accumulation of cerebrospinal fluid, resulting in elevated intracranial pressure (ICP). It is the leading cause for brain surgery in newborns, often causing long-term neurologic disabilities or even death. Since conventional invasive ICP monitoring is risky, early neurosurgical interventions could benefit from noninvasive techniques. Here we use clinical contrast-enhanced ultrasound (CEUS) imaging and intravascular microbubble tracking algorithms to map the cerebral blood flow in hydrocephalic pediatric porcine models. Regional microvascular perfusions are quantified by the cerebral microcirculation (CMC) parameter, which accounts for the concentration of micro-vessels and flow velocity in them. Combining CMC with hemodynamic parameters yields functional relationships between cortical micro-perfusion and ICP, with correlation coefficients exceeding 0.85. For cerebral ischemia cases, the nondimensionalized cortical micro-perfusion decreases by an order of magnitude when ICP exceeds 50% of the MAP. These findings suggest that CEUS-based CMC measurement is a plausible noninvasive method for assessing the ICP and detecting ischemia.
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Affiliation(s)
- Zeng Zhang
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Misun Hwang
- Department of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, USA.,Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Todd J Kilbaugh
- Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Anush Sridharan
- Department of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Joseph Katz
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, USA.
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12
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Accounting for arterial and capillary blood gases for calculation of cerebral blood flow in preterm infants. Eur J Pediatr 2022; 181:2087-2096. [PMID: 35150310 PMCID: PMC9056440 DOI: 10.1007/s00431-022-04392-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 01/14/2022] [Accepted: 01/22/2022] [Indexed: 12/04/2022]
Abstract
UNLABELLED One of the most feared neurological complications of premature birth is intraventricular hemorrhage, frequently triggered by fluctuations in cerebral blood flow (CBF). Although several techniques for CBF measurement have been developed, they are not part of clinical routine in neonatal intensive care. A promising tool for monitoring of CBF is its numerical assessment using standard clinical parameters such as mean arterial pressure, carbon dioxide partial pressure (pCO2) and oxygen partial pressure (pO2). A standard blood gas analysis is performed on arterial blood. In neonates, capillary blood is widely used for analysis of blood gas parameters. The purpose of this study was the assessment of differences between arterial and capillary analysis of blood gases and adjustment of the mathematical model for CBF calculation to capillary values. The statistical analysis of pCO2 and pO2 values collected from 254 preterm infants with a gestational age of 23-30 weeks revealed no significant differences between arterial and capillary pCO2 and significantly lower values for capillary pO2. The estimated mean differences between arterial and capillary pO2 of 15.15 mmHg (2.02 kPa) resulted in a significantly higher CBF calculated for capillary pO2 compared to CBF calculated for arterial pO2. Two methods for correction of capillary pO2 were proposed and compared, one based on the mean difference and another one based on a regression model. CONCLUSION Capillary blood gas analysis with correction for pO2 as proposed in the present work is an acceptable alternative to arterial sampling for the assessment of CBF. WHAT IS KNOWN • Arterial blood analysis is the gold standard in clinical practice. However, capillary blood is widely used for estimating blood gas parameters. • There is no significant difference between the arterial and capillary pCO2 values, but the capillary pO2 differs significantly from the arterial one. WHAT IS NEW • The lower capillary pO2 values yield significantly higher values of calculated CBF compared to CBF computed from arterial pO2 measurements. • Two correction methods for the adjustment of capillary pO2 to arterial pO2 that made the difference in the calculated CBF insignificant have been proposed.
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13
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Sidorenko I, Turova V, Rieger-Fackeldey E, Felderhoff-Müser U, Kovtanyuk A, Brodkorb S, Lampe R. Mathematical modeling of the hematocrit influence on cerebral blood flow in preterm infants. PLoS One 2021; 16:e0261819. [PMID: 34962951 PMCID: PMC8714087 DOI: 10.1371/journal.pone.0261819] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 12/10/2021] [Indexed: 11/19/2022] Open
Abstract
Premature birth is one of the most important factors increasing the risk for brain damage in newborns. Development of an intraventricular hemorrhage in the immature brain is often triggered by fluctuations of cerebral blood flow (CBF). Therefore, monitoring of CBF becomes an important task in clinical care of preterm infants. Mathematical modeling of CBF can be a complementary tool in addition to diagnostic tools in clinical practice and research. The purpose of the present study is an enhancement of the previously developed mathematical model for CBF by a detailed description of apparent blood viscosity and vessel resistance, accounting for inhomogeneous hematocrit distribution in multiscale blood vessel architectures. The enhanced model is applied to our medical database retrospectively collected from the 254 preterm infants with a gestational age of 23-30 weeks. It is shown that by including clinically measured hematocrit in the mathematical model, apparent blood viscosity, vessel resistance, and hence the CBF are strongly affected. Thus, a statistically significant decrease in hematocrit values observed in the group of preterm infants with intraventricular hemorrhage resulted in a statistically significant increase in calculated CBF values.
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Affiliation(s)
- Irina Sidorenko
- Chair of Mathematical Modeling, Mathematical Faculty, Technical University of Munich, Garching, Germany
| | - Varvara Turova
- Research Unit for Pediatric Neuroorthopedics and Cerebral Palsy of the Buhl-Strohmaier Foundation, Orthopedic Department, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Esther Rieger-Fackeldey
- Department of Pediatrics, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Ursula Felderhoff-Müser
- Neonatology, Pediatric Intensive Care, Pediatric Neurology, Department of Pediatrics I, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Andrey Kovtanyuk
- Research Unit for Pediatric Neuroorthopedics and Cerebral Palsy of the Buhl-Strohmaier Foundation, Orthopedic Department, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Silke Brodkorb
- Neonatology Department, Munich Clinic Harlaching, Munich, Germany
| | - Renée Lampe
- Research Unit for Pediatric Neuroorthopedics and Cerebral Palsy of the Buhl-Strohmaier Foundation, Orthopedic Department, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
- * E-mail:
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14
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Koep JL, Taylor CE, Coombes JS, Bond B, Ainslie PN, Bailey TG. Autonomic control of cerebral blood flow: fundamental comparisons between peripheral and cerebrovascular circulations in humans. J Physiol 2021; 600:15-39. [PMID: 34842285 DOI: 10.1113/jp281058] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 11/25/2021] [Indexed: 01/12/2023] Open
Abstract
Understanding the contribution of the autonomic nervous system to cerebral blood flow (CBF) control is challenging, and interpretations are unclear. The identification of calcium channels and adrenoreceptors within cerebral vessels has led to common misconceptions that the function of these receptors and actions mirror those of the peripheral vasculature. This review outlines the fundamental differences and complex actions of cerebral autonomic activation compared with the peripheral circulation. Anatomical differences, including the closed nature of the cerebrovasculature, and differential adrenoreceptor subtypes, density, distribution and sensitivity, provide evidence that measures on peripheral sympathetic nerve activity cannot be extrapolated to the cerebrovasculature. Cerebral sympathetic nerve activity seems to act opposingly to the peripheral circulation, mediated at least in part by changes in intracranial pressure and cerebral blood volume. Additionally, heterogeneity in cerebral adrenoreceptor distribution highlights region-specific autonomic regulation of CBF. Compensatory chemo- and autoregulatory responses throughout the cerebral circulation, and interactions with parasympathetic nerve activity are unique features to the cerebral circulation. This crosstalk between sympathetic and parasympathetic reflexes acts to ensure adequate perfusion of CBF to rising and falling perfusion pressures, optimizing delivery of oxygen and nutrients to the brain, while attempting to maintain blood volume and intracranial pressure. Herein, we highlight the distinct similarities and differences between autonomic control of cerebral and peripheral blood flow, and the regional specificity of sympathetic and parasympathetic regulation within the cerebrovasculature. Future research directions are outlined with the goal to further our understanding of autonomic control of CBF in humans.
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Affiliation(s)
- Jodie L Koep
- Physiology and Ultrasound Laboratory in Science and Exercise, Centre for Research on Exercise, Physical Activity and Health, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia.,Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Chloe E Taylor
- School of Health Sciences, Western Sydney University, Sydney, Australia
| | - Jeff S Coombes
- Physiology and Ultrasound Laboratory in Science and Exercise, Centre for Research on Exercise, Physical Activity and Health, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Bert Bond
- Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Tom G Bailey
- Physiology and Ultrasound Laboratory in Science and Exercise, Centre for Research on Exercise, Physical Activity and Health, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia.,School of Nursing, Midwifery and Social Work, The University of Queensland, Brisbane, Queensland, Australia
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15
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Li W, Liu D, van Zijl PCM, Qin Q. Three-dimensional whole-brain mapping of cerebral blood volume and venous cerebral blood volume using Fourier transform-based velocity-selective pulse trains. Magn Reson Med 2021; 86:1420-1433. [PMID: 33955583 DOI: 10.1002/mrm.28815] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 03/28/2021] [Accepted: 04/01/2021] [Indexed: 12/21/2022]
Abstract
PURPOSE To develop 3D MRI methods for cerebral blood volume (CBV) and venous cerebral blood volume (vCBV) estimation with whole-brain coverage using Fourier transform-based velocity-selective (FT-VS) pulse trains. METHODS For CBV measurement, FT-VS saturation pulse trains were used to suppress static tissue, whereas CSF contamination was corrected voxel-by-voxel using a multi-readout acquisition and a fast CSF T2 scan. The vCBV mapping was achieved by inserting an arterial-nulling module that included a FT-VS inversion pulse train. Using these methods, CBV and vCBV maps were obtained on 6 healthy volunteers at 3 T. RESULTS The mean CBV and vCBV values in gray matter and white matter in different areas of the brain showed high correlation (r = 0.95 and P < .0001). The averaged CBV and vCBV values of the whole brain were 5.4 ± 0.6 mL/100 g and 2.5 ± 0.3 mL/100 g in gray matter, and 2.6 ± 0.5 mL/100 g and 1.5 ± 0.2 mL/100 g in white matter, respectively, comparable to the literature. CONCLUSION The feasibility of FT-VS-based CBV and vCBV estimation was demonstrated for 3D acquisition with large spatial coverage.
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Affiliation(s)
- Wenbo Li
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Dapeng Liu
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Peter C M van Zijl
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Qin Qin
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
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16
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de Haan W, Dheedene W, Apelt K, Décombas-Deschamps S, Vinckier S, Verhulst S, Conidi A, Deffieux T, Staring MW, Vandervoort P, Caluwé E, Lox M, Mannaerts I, Takagi T, Jaekers J, Berx G, Haigh J, Topal B, Zwijsen A, Higashi Y, van Grunsven LA, van IJcken WFJ, Mulugeta E, Tanter M, Lebrin FPG, Huylebroeck D, Luttun A. Endothelial Zeb2 preserves the hepatic angioarchitecture and protects against liver fibrosis. Cardiovasc Res 2021; 118:1262-1275. [PMID: 33909875 PMCID: PMC8953454 DOI: 10.1093/cvr/cvab148] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 04/26/2021] [Indexed: 02/06/2023] Open
Abstract
Aims Hepatic capillaries are lined with specialized liver sinusoidal endothelial cells (LSECs) which support macromolecule passage to hepatocytes and prevent fibrosis by keeping hepatic stellate cells (HSCs) quiescent. LSEC specialization is co-determined by transcription factors. The zinc-finger E-box-binding homeobox (Zeb)2 transcription factor is enriched in LSECs. Here, we aimed to elucidate the endothelium-specific role of Zeb2 during maintenance of the liver and in liver fibrosis. Methods and results To study the role of Zeb2 in liver endothelium we generated EC-specific Zeb2 knock-out (ECKO) mice. Sequencing of liver EC RNA revealed that deficiency of Zeb2 results in prominent expression changes in angiogenesis-related genes. Accordingly, the vascular area was expanded and the presence of pillars inside ECKO liver vessels indicated that this was likely due to increased intussusceptive angiogenesis. LSEC marker expression was not profoundly affected and fenestrations were preserved upon Zeb2 deficiency. However, an increase in continuous EC markers suggested that Zeb2-deficient LSECs are more prone to dedifferentiation, a process called ‘capillarization’. Changes in the endothelial expression of ligands that may be involved in HSC quiescence together with significant changes in the expression profile of HSCs showed that Zeb2 regulates LSEC–HSC communication and HSC activation. Accordingly, upon exposure to the hepatotoxin carbon tetrachloride (CCl4), livers of ECKO mice showed increased capillarization, HSC activation, and fibrosis compared to livers from wild-type littermates. The vascular maintenance and anti-fibrotic role of endothelial Zeb2 was confirmed in mice with EC-specific overexpression of Zeb2, as the latter resulted in reduced vascularity and attenuated CCl4-induced liver fibrosis. Conclusion Endothelial Zeb2 preserves liver angioarchitecture and protects against liver fibrosis. Zeb2 and Zeb2-dependent genes in liver ECs may be exploited to design novel therapeutic strategies to attenuate hepatic fibrosis.
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Affiliation(s)
- Willeke de Haan
- Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Wouter Dheedene
- Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Katerina Apelt
- Department of Internal Medicine (Nephrology), Einthoven Laboratory for Experimental Vascular Medicine. Leiden University Medical Center, . Leiden, The Netherlands
| | - Sofiane Décombas-Deschamps
- Physics for Medicine Paris, Inserm, CNRS, ESPCI Paris, Paris Sciences et Lettres University, Paris, France
| | - Stefan Vinckier
- Department of Oncology, Laboratory of Angiogenesis and Vascular Metabolism, KU Leuven, Leuven, Belgium.,Laboratory of Angiogenesis and Vascular Metabolism, Center for Cancer Biology, Vlaams Instituut voor Biotechnologie (VIB), Leuven, Belgium
| | - Stefaan Verhulst
- Liver Cell Biology research group, Vrije Universiteit Brussel, Brussels, Belgium
| | - Andrea Conidi
- Department of Cell Biology, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Thomas Deffieux
- Physics for Medicine Paris, Inserm, CNRS, ESPCI Paris, Paris Sciences et Lettres University, Paris, France
| | - Michael W Staring
- Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Petra Vandervoort
- Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Ellen Caluwé
- Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Marleen Lox
- Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Inge Mannaerts
- Liver Cell Biology research group, Vrije Universiteit Brussel, Brussels, Belgium
| | - Tsuyoshi Takagi
- Department of Disease Model, Institute of Developmental Research, Aichi Developmental Disability Center, Aichi, Japan
| | | | - Geert Berx
- Molecular and Cellular Oncology Laboratory, Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium.,Cancer Research Institute Ghent (CRIG), Ghent, Belgium
| | - Jody Haigh
- Department of Pharmacology and Therapeutics, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada.,Research Institute in Oncology and Hematology, Cancer Care Manitoba, Winnipeg, Manitoba, Canada
| | - Baki Topal
- Abdominal Surgery, UZ Leuven, Leuven, Belgium
| | - An Zwijsen
- Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Yujiro Higashi
- Department of Disease Model, Institute of Developmental Research, Aichi Developmental Disability Center, Aichi, Japan
| | - Leo A van Grunsven
- Liver Cell Biology research group, Vrije Universiteit Brussel, Brussels, Belgium
| | - Wilfred F J van IJcken
- Department of Cell Biology, Erasmus University Medical Center, Rotterdam, The Netherlands.,Center for Biomics-Genomics, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Eskeatnaf Mulugeta
- Department of Cell Biology, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Mickael Tanter
- Physics for Medicine Paris, Inserm, CNRS, ESPCI Paris, Paris Sciences et Lettres University, Paris, France
| | - Franck P G Lebrin
- Department of Internal Medicine (Nephrology), Einthoven Laboratory for Experimental Vascular Medicine. Leiden University Medical Center, . Leiden, The Netherlands.,Physics for Medicine Paris, Inserm, CNRS, ESPCI Paris, Paris Sciences et Lettres University, Paris, France
| | - Danny Huylebroeck
- Department of Cell Biology, Erasmus University Medical Center, Rotterdam, The Netherlands.,Department of Development and Regeneration, KU Leuven, Leuven, Belgium
| | - Aernout Luttun
- Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
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17
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Burley CV, Francis ST, Thomas KN, Whittaker AC, Lucas SJE, Mullinger KJ. Contrasting Measures of Cerebrovascular Reactivity Between MRI and Doppler: A Cross-Sectional Study of Younger and Older Healthy Individuals. Front Physiol 2021; 12:656746. [PMID: 33912073 PMCID: PMC8072486 DOI: 10.3389/fphys.2021.656746] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 03/10/2021] [Indexed: 12/12/2022] Open
Abstract
Cerebrovascular reactivity (CVR) is used as an outcome measure of brain health. Traditionally, lower CVR is associated with ageing, poor fitness and brain-related conditions (e.g. stroke, dementia). Indeed, CVR is suggested as a biomarker for disease risk. However, recent findings report conflicting associations between ageing or fitness and CVR measures. Inconsistent findings may relate to different neuroimaging modalities used, which include transcranial Doppler (TCD) and blood-oxygen-level-dependant (BOLD) contrast magnetic resonance imaging (MRI). We assessed the relationship between CVR metrics derived from two common imaging modalities, TCD and BOLD MRI, within the same individuals and with expected significant differences (i.e., younger vs. older) to maximise the expected spread in measures. We conducted two serial studies using TCD- and MRI-derived measures of CVR (via inspired 5% CO2 in air). Study 1 compared 20 younger (24 ± 7 years) with 15 older (66 ± 7 years) participants, Study 2 compared 10 younger (22 ± 2 years) with 10 older (72 ± 4 years) participants. Combining the main measures across studies, no significant correlation (r = 0.15, p = 0.36) was observed between individual participant TCD- and BOLD-CVR measures. Further, these measures showed differential effects between age groups; with TCD-CVR higher in the older compared to younger group (4 ± 1 vs. 3 ± 1 %MCAv/mmHg P ET CO2; p < 0.05, Hedges' g = 0.75), whereas BOLD-CVR showed no difference (p = 0.104, Hedges' g = 0.38). In Study 2 additional measures were obtained to understand the origin of the discrepancy: phase contrast angiography (PCA) MRI of the middle cerebral artery, showed a significantly lower blood flow (but not velocity) CVR response in older compared with younger participants (p > 0.05, Hedges' g = 1.08). The PCA CVR metrics did not significantly correlate with the BOLD- or TCD-CVR measures. The differing CVR observations between imaging modalities were despite expected, correlated (r = 0.62-0.82), age-related differences in resting CBF measures across modalities. Taken together, findings across both studies show no clear relationship between TCD- and BOLD-CVR measures. We hypothesize that CVR differences between imaging modalities are in part due to the aspects of the vascular tree that are assessed (TCD:arteries; BOLD:venules/veins). Further work is needed to understand the between-modality CVR response differences, but caution is needed when comparing CVR metrics derived from different imaging modalities.
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Affiliation(s)
- Claire V. Burley
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
- Centre for Human Brain Health, University of Birmingham, Birmingham, United Kingdom
- Dementia Centre for Research Collaboration, School of Psychiatry, University of New South Wales, Sydney, NSW, Australia
| | - Susan T. Francis
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom
| | - Kate N. Thomas
- Department of Surgical Sciences, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Anna C. Whittaker
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
- Faculty of Health Sciences and Sport, University of Stirling, Stirling, United Kingdom
| | - Samuel J. E. Lucas
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
- Centre for Human Brain Health, University of Birmingham, Birmingham, United Kingdom
| | - Karen J. Mullinger
- Centre for Human Brain Health, University of Birmingham, Birmingham, United Kingdom
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom
- School of Psychology, University of Birmingham, Birmingham, United Kingdom
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18
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Abstract
BACKGROUND Adenosine stress T1 mapping is an emerging magnetic resonance imaging method to investigate coronary vascular function and myocardial ischemia without application of a contrast agent. Using gene-modified mice and 2 vasodilators, we elucidated and compared the mechanisms of adenosine myocardial perfusion imaging and adenosine T1 mapping. METHODS Wild-type (WT), A2AAR-/- (adenosine A2A receptor knockout), A2BAR-/- (adenosine A2B receptor knockout), A3AR-/- (adenosine A3 receptor knockout), and eNOS-/- (endothelial nitric oxide synthase knockout) mice underwent rest and stress perfusion magnetic resonance imaging (n=8) and T1 mapping (n=10) using either adenosine, regadenoson (a selective A2AAR agonist), or saline. Myocardial blood flow and T1 were computed from perfusion imaging and T1 mapping, respectively, at rest and stress to assess myocardial perfusion reserve and T1 reactivity (ΔT1). Changes in heart rate for each stress agent were also calculated. Two-way ANOVA was used to detect differences in each parameter between the different groups of mice. RESULTS Myocardial perfusion reserve was significantly reduced only in A2AAR-/- compared to WT mice using adenosine (1.06±0.16 versus 2.03±0.52, P<0.05) and regadenoson (0.98±026 versus 2.13±0.75, P<0.05). In contrast, adenosine ΔT1 was reduced compared with WT mice (3.88±1.58) in both A2AAR-/- (1.63±1.32, P<0.05) and A2BAR-/- (1.55±1.35, P<0.05). Furthermore, adenosine ΔT1 was halved in eNOS-/- (1.76±1.46, P<0.05) versus WT mice. Regadenoson ΔT1 was approximately half of adenosine ΔT1 in WT mice (1.97±1.50, P<0.05), and additionally, it was significantly reduced in eNOS-/- mice (-0.22±1.46, P<0.05). Lastly, changes in heart rate was 2× greater using regadenoson versus adenosine in all groups except A2AAR-/-, where heart rate remained constant. CONCLUSIONS The major findings are that (1) although adenosine myocardial perfusion reserve is mediated through the A2A receptor, adenosine ΔT1 is mediated through the A2A and A2B receptors, (2) adenosine myocardial perfusion reserve is endothelial independent while adenosine ΔT1 is partially endothelial dependent, and (3) ΔT1 mediated through the A2A receptor is endothelial dependent while ΔT1 mediated through the A2B receptor is endothelial independent.
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Affiliation(s)
- Soham A Shah
- Department of Biomedical Engineering (S.A.S., C.E.R., B.A.F., F.H.E.), University of Virginia, Charlottesville, VA
| | - Claire E Reagan
- Department of Radiology (B.A.F., F.H.E.), University of Virginia, Charlottesville, VA
| | - Brent A French
- Department of Biomedical Engineering (S.A.S., C.E.R., B.A.F., F.H.E.), University of Virginia, Charlottesville, VA.,Department of Radiology (B.A.F., F.H.E.), University of Virginia, Charlottesville, VA.,The Robert M. Berne Cardiovascular Research Center (B.A.F., F.H.E.), University of Virginia, Charlottesville, VA
| | - Frederick H Epstein
- Department of Biomedical Engineering (S.A.S., C.E.R., B.A.F., F.H.E.), University of Virginia, Charlottesville, VA.,Department of Radiology (B.A.F., F.H.E.), University of Virginia, Charlottesville, VA.,The Robert M. Berne Cardiovascular Research Center (B.A.F., F.H.E.), University of Virginia, Charlottesville, VA
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19
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Sidorenko I, Turova V, Botkin N, Kovtanyuk A, Eckardt L, Alves-Pinto A, Felderhoff-Müser U, Rieger-Fackeldey E, Lampe R. Assessing haemorrhage-critical values of cerebral blood flow by modelling biomechanical stresses on capillaries in the immature brain. Sci Rep 2020; 10:14196. [PMID: 32848187 PMCID: PMC7449973 DOI: 10.1038/s41598-020-71087-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 08/06/2020] [Indexed: 11/09/2022] Open
Abstract
The development of intraventricular haemorrhages (IVH) in preterm newborns is triggered by a disruption of the vessels responsible for cerebral microcirculation. Analysis of the stresses exerted on vessel walls enables the identification of the critical values of cerebral blood flow (CBF) associated with the development of IVH in preterm infants. The purpose of the present study is the estimation of these critical CBF values using the biomechanical stresses obtained by the finite element modelling of immature brain capillaries. The properties of the endothelial cells and basement membranes employed were selected on the basis of published nanoindentation measurements using atomic force microscopes. The forces acting on individual capillaries were derived with a mathematical model that accounts for the peculiarities of microvascularity in the immature brain. Calculations were based on clinical measurements obtained from 254 preterm infants with the gestational age ranging from 23 to 30 weeks, with and without diagnosis of IVH. No distinction between the affected and control groups with the gestational age of 23 to 26 weeks was possible. For infants with the gestational age of 27 to 30 weeks, the CBF value of 17.03 ml/100 g/min was determined as the critical upper value, above which the likelihood of IVH increases.
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Affiliation(s)
- Irina Sidorenko
- Mathematical Faculty, Chair of Mathematical Modelling, Technical University of Munich, Boltzmannstr. 3, 85748, Garching, Germany
| | - Varvara Turova
- School of Medicine, Klinikum Rechts Der Isar, Orthopedic Department, Research Unit for Pediatric Neuroorthopedics and Cerebral Palsy of the Buhl-Strohmaier Foundation, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany
| | - Nikolai Botkin
- Mathematical Faculty, Chair of Mathematical Modelling, Technical University of Munich, Boltzmannstr. 3, 85748, Garching, Germany
| | - Andrey Kovtanyuk
- School of Medicine, Klinikum Rechts Der Isar, Orthopedic Department, Research Unit for Pediatric Neuroorthopedics and Cerebral Palsy of the Buhl-Strohmaier Foundation, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany
| | - Laura Eckardt
- Department of Pediatrics I, Neonatology, Pediatric Intensive Care, Pediatric Neurology, Department of Pediatrics III, Pediatric Oncology, University Duisburg-Essen, University Hospital Essen, Hufelandstraße 55, 45147, Essen, Germany
| | - Ana Alves-Pinto
- School of Medicine, Klinikum Rechts Der Isar, Orthopedic Department, Research Unit for Pediatric Neuroorthopedics and Cerebral Palsy of the Buhl-Strohmaier Foundation, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany
| | - Ursula Felderhoff-Müser
- Department of Pediatrics I, Neonatology, Pediatric Intensive Care, Pediatric Neurology, Department of Pediatrics III, Pediatric Oncology, University Duisburg-Essen, University Hospital Essen, Hufelandstraße 55, 45147, Essen, Germany
| | - Esther Rieger-Fackeldey
- School of Medicine, Klinikum Rechts Der Isar, Department of Pediatrics, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany
| | - Renée Lampe
- School of Medicine, Klinikum Rechts Der Isar, Orthopedic Department, Research Unit for Pediatric Neuroorthopedics and Cerebral Palsy of the Buhl-Strohmaier Foundation, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany.
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20
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Nonstationary Model of Oxygen Transport in Brain Tissue. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2020; 2020:4861654. [PMID: 32733594 PMCID: PMC7369669 DOI: 10.1155/2020/4861654] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 05/16/2020] [Indexed: 11/18/2022]
Abstract
The paper addresses the mathematical study of a nonstationary continuum model describing oxygen propagation in cerebral substance. The model allows to estimate the rate of oxygen saturation and stabilization of oxygen concentration in relatively large parts of cerebral tissue. A theoretical and numerical analysis of the model is performed. The unique solvability of the underlying initial-boundary value problem for a system of coupled nonlinear parabolic equations is proved. In the numerical experiment, the tissue oxygen saturation after hypoxia is analyzed for the case when a sufficient amount of oxygen begins to flow into the capillary network. A fast stabilization of the tissue oxygen concentration is demonstrated. The reliability of the results of the numerical simulation is discussed.
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Rahal L, Thibaut M, Rivals I, Claron J, Lenkei Z, Sitt JD, Tanter M, Pezet S. Ultrafast ultrasound imaging pattern analysis reveals distinctive dynamic brain states and potent sub-network alterations in arthritic animals. Sci Rep 2020; 10:10485. [PMID: 32591574 PMCID: PMC7320008 DOI: 10.1038/s41598-020-66967-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 05/29/2020] [Indexed: 01/20/2023] Open
Abstract
Chronic pain pathologies, which are due to maladaptive changes in the peripheral and/or central nervous systems, are debilitating diseases that affect 20% of the European adult population. A better understanding of the mechanisms underlying this pathogenesis would facilitate the identification of novel therapeutic targets. Functional connectivity (FC) extracted from coherent low-frequency hemodynamic fluctuations among cerebral networks has recently brought light on a powerful approach to study large scale brain networks and their disruptions in neurological/psychiatric disorders. Analysis of FC is classically performed on averaged signals over time, but recently, the analysis of the dynamics of FC has also provided new promising information. Keeping in mind the limitations of animal models of persistent pain but also the powerful tool they represent to improve our understanding of the neurobiological basis of chronic pain pathogenicity, this study aimed at defining the alterations in functional connectivity, in a clinically relevant animal model of sustained inflammatory pain (Adjuvant-induced Arthritis) in rats by using functional ultrasound imaging, a neuroimaging technique with a unique spatiotemporal resolution (100 μm and 2 ms) and sensitivity. Our results show profound alterations of FC in arthritic animals, such as a subpart of the somatomotor (SM) network, occurring several weeks after the beginning of the disease. Also, we demonstrate for the first time that dynamic functional connectivity assessed by ultrasound can provide quantitative and robust information on the dynamic pattern that we define as brain states. While the main state consists of an overall synchrony of hemodynamic fluctuations in the SM network, arthritic animal spend statistically more time in two other states, where the fluctuations of the primary sensory cortex of the inflamed hind paws show asynchrony with the rest of the SM network. Finally, correlating FC changes with pain behavior in individual animals suggest links between FC alterations and either the cognitive or the emotional aspects of pain. Our study introduces fUS as a new translational tool for the enhanced understanding of the dynamic pain connectome and brain plasticity in a major preclinical model of chronic pain.
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Affiliation(s)
- Line Rahal
- Laboratory of Brain Plasticity, ESPCI Paris, PSL Research University, CNRS UMR 8249, 10 rue Vauquelin, 75005, Paris, France
- Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research University, Paris, France
| | - Miguel Thibaut
- Laboratory of Brain Plasticity, ESPCI Paris, PSL Research University, CNRS UMR 8249, 10 rue Vauquelin, 75005, Paris, France
| | - Isabelle Rivals
- Equipe de Statistique Appliquée, ESPCI Paris, PSL Research University, UMRS 1158, 10 rue Vauquelin, 75005, Paris, France
| | - Julien Claron
- Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research University, Paris, France
| | - Zsolt Lenkei
- Laboratory of Brain Plasticity, ESPCI Paris, PSL Research University, CNRS UMR 8249, 10 rue Vauquelin, 75005, Paris, France
- Center of Psychiatry and Neurosciences, INSERM U894, 102 rue de la Santé, 75014, Paris, France
| | - Jacobo D Sitt
- Institut du Cerveau et de la Moelle, INSERM U1127, CNRS UMR 7225, Sorbonne University, UPMC Univ Paris 06 UMR, S 1127, Paris, France
| | - Mickael Tanter
- Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research University, Paris, France
| | - Sophie Pezet
- Laboratory of Brain Plasticity, ESPCI Paris, PSL Research University, CNRS UMR 8249, 10 rue Vauquelin, 75005, Paris, France.
- Physics for Medicine Paris, Inserm, ESPCI Paris, CNRS, PSL Research University, Paris, France.
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Driver ID, Traat M, Fasano F, Wise RG. Most Small Cerebral Cortical Veins Demonstrate Significant Flow Pulsatility: A Human Phase Contrast MRI Study at 7T. Front Neurosci 2020; 14:415. [PMID: 32431591 PMCID: PMC7214844 DOI: 10.3389/fnins.2020.00415] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 04/06/2020] [Indexed: 12/22/2022] Open
Abstract
Phase contrast MRI (pcMRI) has been used to investigate flow pulsatility in cerebral arteries, larger cerebral veins, and the cerebrospinal fluid (CSF). Such measurements of intracranial pulsatility and compliance are beginning to inform understanding of the pathophysiology of conditions including normal pressure hydrocephalus, multiple sclerosis, and dementias. We demonstrate the presence of flow pulsatility in small cerebral cortical veins, for the first time using pcMRI at 7 T, with the aim of improving our understanding of the hemodynamics of this little-studied vascular compartment. A method for establishing where venous flow is pulsatile is introduced, revealing significant pulsatility in 116 out of 146 veins, across eight healthy participants, assessed in parietal and frontal regions. Distributions of pulsatility index (PI) and pulse waveform delay were characterized, indicating a small, but statistically significant (p < 0.05), delay of 59 ± 41 ms in cortical veins with respect to the superior sagittal sinus, but no differences between veins draining different arterial supply territories. Measurements of pulsatility in smaller cortical veins, a hitherto unstudied compartment closer to the capillary bed, could lead to a better understanding of intracranial compliance and cerebrovascular (patho)physiology.
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Affiliation(s)
- Ian D Driver
- Cardiff University Brain Research Imaging Centre, School of Psychology, Cardiff University, Cardiff, United Kingdom
| | - Maarika Traat
- Cardiff University Brain Research Imaging Centre, School of Psychology, Cardiff University, Cardiff, United Kingdom.,Institute of Psychology, University of Tartu, Tartu, Estonia
| | | | - Richard G Wise
- Cardiff University Brain Research Imaging Centre, School of Psychology, Cardiff University, Cardiff, United Kingdom.,Department of Neuroscience, Imaging and Clinical Sciences, "G. D'Annunzio University" of Chieti-Pescara, Chieti, Italy.,Institute for Advanced Biomedical Technologies, "G. D'Annunzio University" of Chieti-Pescara, Chieti, Italy
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Duffin J, Hare GM, Fisher JA. A mathematical model of cerebral blood flow control in anaemia and hypoxia. J Physiol 2020; 598:717-730. [DOI: 10.1113/jp279237] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 12/02/2019] [Indexed: 12/21/2022] Open
Affiliation(s)
- James Duffin
- Departments of Anaesthesia and PhysiologyUniversity of Toronto Toronto Ontario Canada
- Thornhill Research Inc. Toronto Ontario Canada
| | - Gregory M.T Hare
- Departments of Anaesthesia and PhysiologyUniversity of Toronto Toronto Ontario Canada
- Department of AnesthesiaKeenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St Michael's HospitalUnity Health Toronto Toronto Ontario Canada
| | - Joseph A. Fisher
- Departments of Anaesthesia and PhysiologyUniversity of Toronto Toronto Ontario Canada
- Thornhill Research Inc. Toronto Ontario Canada
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Turova V, Sidorenko I, Eckardt L, Rieger-Fackeldey E, Felderhoff-Müser U, Alves-Pinto A, Lampe R. Machine learning models for identifying preterm infants at risk of cerebral hemorrhage. PLoS One 2020; 15:e0227419. [PMID: 31940391 PMCID: PMC6961932 DOI: 10.1371/journal.pone.0227419] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 12/18/2019] [Indexed: 11/18/2022] Open
Abstract
Intracerebral hemorrhage in preterm infants is a major cause of brain damage and cerebral palsy. The pathogenesis of cerebral hemorrhage is multifactorial. Among the risk factors are impaired cerebral autoregulation, infections, and coagulation disorders. Machine learning methods allow the identification of combinations of clinical factors to best differentiate preterm infants with intra-cerebral bleeding and the development of models for patients at risk of cerebral hemorrhage. In the current study, a Random Forest approach is applied to develop such models for extremely and very preterm infants (23-30 weeks gestation) based on data collected from a cohort of 229 individuals. The constructed models exhibit good prediction accuracy and might be used in clinical practice to reduce the risk of cerebral bleeding in prematurity.
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Affiliation(s)
- Varvara Turova
- Research Unit for Pediatric Neuroorthopedics and Cerebral Palsy of the Buhl-Strohmaier Foundation, Orthopedic Department, Klinikum Rechts der Isar, Technical University of Munich, München, Germany
- * E-mail:
| | - Irina Sidorenko
- Chair of Mathematical Modelling, Mathematical Faculty, Technical University of Munich, Garching bei München, Germany
| | - Laura Eckardt
- Departments of Pediatrics and Neonatology, University Hospital Essen, University of Duisburg‐Essen, Essen, Germany
| | - Esther Rieger-Fackeldey
- Department of Pediatrics, Neonatology, Klinikum Rechts der Isar, Technical University of Munich, München, Germany
| | - Ursula Felderhoff-Müser
- Departments of Pediatrics and Neonatology, University Hospital Essen, University of Duisburg‐Essen, Essen, Germany
| | - Ana Alves-Pinto
- Research Unit for Pediatric Neuroorthopedics and Cerebral Palsy of the Buhl-Strohmaier Foundation, Orthopedic Department, Klinikum Rechts der Isar, Technical University of Munich, München, Germany
| | - Renée Lampe
- Research Unit for Pediatric Neuroorthopedics and Cerebral Palsy of the Buhl-Strohmaier Foundation, Orthopedic Department, Klinikum Rechts der Isar, Technical University of Munich, München, Germany
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Assessing key clinical parameters before and after intraventricular hemorrhage in very preterm infants. Eur J Pediatr 2020; 179:929-937. [PMID: 31993776 PMCID: PMC7220978 DOI: 10.1007/s00431-020-03585-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 01/15/2020] [Accepted: 01/16/2020] [Indexed: 11/17/2022]
Abstract
Intraventricular cerebral hemorrhage (IVH) is one of the most severe complications of premature birth, potentially leading to lifelong disability. The purpose of this paper is the assessment of the evolution of three of the most relevant parameters, before and after IVH: mean arterial pressure (MAP), arterial carbon dioxide pressure (pCO2), and cerebral blood flow (CBF). Clinical records of 254 preterm infants with a gestational age of 23-30 weeks, with and without a diagnosis of IVH, were reviewed for MAP and arterial pCO2 in the period up to 7 days before and 3 days after IVH or during the first 10 days of life in cases without IVH.Conclusion: A statistically significant increase in pCO2 and decrease in MAP in patients with IVH compared with those without were detected. Both the mean values and the mean absolute deviations of CBF were computed in this study, and the latter was significantly higher than in control group. High deviations of CBF, as well as hypercapnia and hypotension, are likely to contribute to the rupture of cerebral blood vessels in preterm infants, and consequently, to the development of IVH.What is Known:• The origin of IVH is multifactorial, but mean arterial pressure, carbon dioxide partial pressure, and cerebral blood flow are recognized as the most important parameters.• In premature infants, the autoregulation mechanisms are still underdeveloped and cannot compensate for cerebral blood flow fluctuations.What is New:• The numerical simulation of CBF is shown to be a promising approach that may be useful in the care of preterm infants.• The mean values of CBF before and after IVH in the affected group were similar to those in the control group, but the mean absolute deviations of CBF in the affected group before and after IVH were significantly higher than that in the control group.
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26
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Accounting for Tube Hematocrit in Modeling of Blood Flow in Cerebral Capillary Networks. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2019; 2019:4235937. [PMID: 31531122 PMCID: PMC6721022 DOI: 10.1155/2019/4235937] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 02/03/2019] [Accepted: 07/28/2019] [Indexed: 11/18/2022]
Abstract
The aim of this paper consists in the derivation of an analytic formula for the hydraulic resistance of capillaries, taking into account the tube hematocrit level. The consistency of the derived formula is verified using Finite Element simulations. Such an effective formula allows for assigning resistances, depending on the hematocrit level, to the edges of networks modeling biological capillary systems, which extends our earlier models of blood flow through large capillary networks. Numerical simulations conducted for large capillary networks with random topologies demonstrate the importance of accounting for the hematocrit level for obtaining consistent results.
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27
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Qin Q, Qu Y, Li W, Liu D, Shin T, Zhao Y, Lin DD, van Zijl PC, Wen Z. Cerebral blood volume mapping using Fourier-transform-based velocity-selective saturation pulse trains. Magn Reson Med 2019; 81:3544-3554. [PMID: 30737847 PMCID: PMC6820852 DOI: 10.1002/mrm.27668] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 11/28/2018] [Accepted: 12/30/2018] [Indexed: 12/21/2022]
Abstract
PURPOSE Velocity-selective saturation (VSS) pulse trains provide a viable alternative to the spatially selective methods for measuring cerebral blood volume (CBV) by reducing the sensitivity to arterial transit time. This study is to compare the Fourier-transform-based velocity-selective saturation (FT-VSS) pulse trains with the conventional flow-dephasing VSS techniques for CBV quantification. METHODS The proposed FT-VSS label and control modules were compared with VSS pulse trains utilizing double refocused hyperbolic tangent (DRHT) and 8-segment B1-insensitive rotation (BIR-8). This was done using both numerical simulations and phantom studies to evaluate their sensitivities to gradient imperfections such as eddy currents. DRHT, BIR-8, and FT-VSS prepared CBV mapping was further compared for velocity-encoding gradients along 3 orthogonal directions in healthy subjects at 3T. RESULTS The phantom studies exhibited more consistent immunity to gradient imperfections for the utilized FT-VSS pulse trains. Compared to DRHT and BIR-8, FT-VSS delivered more robust CBV results across the 3 VS encoding directions with significantly reduced artifacts along the superior-inferior direction and improved temporal signal-to-noise ratio (SNR) values. Average CBV values obtained from FT-VSS based sequences were 5.3 mL/100 g for gray matter and 2.3 mL/100 g for white matter, comparable to literature expectations. CONCLUSION Absolute CBV quantification utilizing advanced FT-VSS pulse trains had several advantages over the existing approaches using flow-dephasing VSS modules. A greater immunity to gradient imperfections and the concurrent tissue background suppression of FT-VSS pulse trains enabled more robust CBV measurements and higher SNR than the conventional VSS pulse trains.
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Affiliation(s)
- Qin Qin
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Yaoming Qu
- Department of Radiology, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong Province, China
| | - Wenbo Li
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Dapeng Liu
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Taehoon Shin
- Division of Mechanical and Biomedical Engineering, Ewha Womans University, Seoul, South Korea
- Department of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | | | - Doris D. Lin
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Peter C.M. van Zijl
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Zhibo Wen
- Department of Radiology, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong Province, China
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28
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Rosmini S, Bulluck H, Captur G, Treibel TA, Abdel-Gadir A, Bhuva AN, Culotta V, Merghani A, Fontana M, Maestrini V, Herrey AS, Chow K, Thompson RB, Piechnik SK, Kellman P, Manisty C, Moon JC. Myocardial native T1 and extracellular volume with healthy ageing and gender. Eur Heart J Cardiovasc Imaging 2019; 19:615-621. [PMID: 29617988 PMCID: PMC5963299 DOI: 10.1093/ehjci/jey034] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 02/24/2018] [Indexed: 12/13/2022] Open
Abstract
Aims To determine how native myocardial T1 and extracellular volume (ECV) change with age, both to understand aging and to inform on normal reference ranges. Methods and results Ninety-four healthy volunteers with no a history or symptoms of cardiovascular disease or diabetes underwent cardiovascular magnetic resonance at 1.5 T. Mid-ventricular short axis native and post-contrast T1 maps by Shortened MOdified Look-Locker Inversion-recovery (ShMOLLI), MOdified Look-Locker Inversion Recovery (MOLLI) [pre-contrast: 5s(3s)3s, post-contrast: 4s(1s)3s(1s)2s] and saturation recovery single-shot acquisition (SASHA) were acquired and ECV by these three techniques were derived for the mid anteroseptum. Mean age was 50 ± 14 years (range 20-76), male 52%, with no age difference between genders (males 51 ± 14 years; females 49 ± 15 years, P = 0.55). Quoting respectively ShMOLLI, MOLLI, SASHA throughout, mean myocardial T1 was 957 ± 30 ms, 1025 ± 38 ms, 1144 ± 45 ms (P < 0.0001) and ECV 28.4 ± 3.0% [95% confidence interval (CI) 27.8-29.0], 27.3 ± 2.7 (95% CI 26.8-27.9), 24.1 ± 2.9% (95% CI 23.5-24.7) (P < 0.0001), with all values higher in females for all techniques (T1 +18 ms, +35 ms, +51 ms; ECV +2.7%, +2.6%, +3.4%). Native myocardial T1 reduced slightly with age (R2 = 0.042, P = 0.048; R2 = 0.131, P < 0.0001-on average by 8-11 ms/decade-but not for SASHA (R2 = 0.033 and P = 0.083). ECV did not change with age (R2 = 0.003, P = 0.582; R2 = 0.002, P = 0.689; R2 = 0.003, P = 0.615). Heart rate decreased slightly with age (R2 = 0.075, coefficient = -0.273, P = 0.008), but there was no relationship between age and other blood T1 influences (haematocrit, iron, high density lipoprotein-cholesterol). Conclusion Gender influences native T1 and ECV with women having a higher native T1 and ECV. Native T1 measured by MOLLI and ShMOLLI was slightly lower with increasing age but not with SASHA and ECV was independent of age for all techniques.
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Affiliation(s)
| | - Heerajnarain Bulluck
- Barts Heart Centre, St. Bartholomew's Hospital, London, UK.,Institute of Cardiovascular Science, University College, West Smithfield, London EC1A 7BE, UK
| | | | | | | | - Anish N Bhuva
- Barts Heart Centre, St. Bartholomew's Hospital, London, UK
| | | | - Ahmed Merghani
- Department of Cardiovascular Sciences, St Georges, University of London, London, UK
| | | | - Viviana Maestrini
- Department of Cardiovascular, Respiratory, Nephrology, Anaesthesiology, and Geriatric Sciences, "Sapienza" University of Rome, Rome, Italy
| | - Anna S Herrey
- Barts Heart Centre, St. Bartholomew's Hospital, London, UK
| | - Kelvin Chow
- Department of Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - Richard B Thompson
- Department of Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Canada
| | - Stefan K Piechnik
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Peter Kellman
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, USA
| | | | - James C Moon
- Barts Heart Centre, St. Bartholomew's Hospital, London, UK.,Institute of Cardiovascular Science, University College, West Smithfield, London EC1A 7BE, UK
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Juttukonda MR, Donahue MJ. Neuroimaging of vascular reserve in patients with cerebrovascular diseases. Neuroimage 2019; 187:192-208. [PMID: 29031532 PMCID: PMC5897191 DOI: 10.1016/j.neuroimage.2017.10.015] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 10/01/2017] [Accepted: 10/07/2017] [Indexed: 12/21/2022] Open
Abstract
Cerebrovascular reactivity, defined broadly as the ability of brain parenchyma to adjust cerebral blood flow in response to altered metabolic demand or a vasoactive stimulus, is being measured with increasing frequency and may have a use for portending new or recurrent stroke risk in patients with cerebrovascular disease. The purpose of this review is to outline (i) the physiological basis of variations in cerebrovascular reactivity, (ii) available approaches for measuring cerebrovascular reactivity in research and clinical settings, and (iii) clinically-relevant cerebrovascular reactivity findings in the context of patients with cerebrovascular disease, including atherosclerotic arterial steno-occlusion, non-atherosclerotic arterial steno-occlusion, anemia, and aging. Literature references summarizing safety considerations for these procedures and future directions for standardizing protocols and post-processing procedures across centers are presented in the specific context of major unmet needs in the setting of cerebrovascular disease.
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Affiliation(s)
- Meher R Juttukonda
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Manus J Donahue
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Psychiatry, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, USA.
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30
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Cheng KS, Lee PF. A Physiological/Model Study on the Effects of Deep Breathing on the Respiration Rate, Oxygen Saturation, and Cerebral Oxygen Delivery in Humans. NEUROPHYSIOLOGY+ 2019. [DOI: 10.1007/s11062-019-09761-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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31
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Hua J, Lee S, Blair NIS, Wyss M, van Bergen JMG, Schreiner SJ, Kagerer SM, Leh SE, Gietl AF, Treyer V, Buck A, Nitsch RM, Pruessmann KP, Lu H, Van Zijl PCM, Albert M, Hock C, Unschuld PG. Increased cerebral blood volume in small arterial vessels is a correlate of amyloid-β-related cognitive decline. Neurobiol Aging 2019; 76:181-193. [PMID: 30738323 DOI: 10.1016/j.neurobiolaging.2019.01.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 01/01/2019] [Accepted: 01/02/2019] [Indexed: 12/22/2022]
Abstract
The protracted accumulation of amyloid-β (Aβ) is a major pathologic hallmark of Alzheimer's disease and may trigger secondary pathological processes that include neurovascular damage. This study was aimed at investigating long-term effects of Aβ burden on cerebral blood volume of arterioles and pial arteries (CBVa), possibly present before manifestation of dementia. Aβ burden was assessed by 11C Pittsburgh compound-B positron emission tomography in 22 controls and 18 persons with mild cognitive impairment (MCI), [ages: 75(±6) years]. After 2 years, inflow-based vascular space occupancy at ultra-high field strength of 7-Tesla was administered for measuring CBVa, and neuropsychological testing for cognitive decline. Crushing gradients were incorporated during MR-imaging to suppress signals from fast-flowing blood in large arteries, and thereby sensitize inflow-based vascular space occupancy to CBVa in pial arteries and arterioles. CBVa was significantly elevated in MCI compared to cognitively normal controls and regional CBVa related to local Aβ deposition. For both MCI and controls, Aβ burden and follow-up CBVa in several brain regions synergistically predicted cognitive decline over 2 years. Orbitofrontal CBVa was positively associated with apolipoprotein E e4 carrier status. Increased CBVa may reflect long-term effects of region-specific pathology associated with Aβ deposition. Additional studies are needed to clarify the role of the arteriolar system and the potential of CBVa as a biomarker for Aβ-related vascular downstream pathology.
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Affiliation(s)
- Jun Hua
- Neurosection, Division of MRI Research, Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - SeungWook Lee
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Nicholas I S Blair
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Michael Wyss
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Jiri M G van Bergen
- Institute for Regenerative Medicine (IREM), University of Zurich, Schlieren, Switzerland
| | - Simon J Schreiner
- Institute for Regenerative Medicine (IREM), University of Zurich, Schlieren, Switzerland; Hospital for Psychogeriatric Medicine, Psychiatric University Hospital Zurich (PUK), Zurich, Switzerland
| | - Sonja M Kagerer
- Institute for Regenerative Medicine (IREM), University of Zurich, Schlieren, Switzerland; Hospital for Psychogeriatric Medicine, Psychiatric University Hospital Zurich (PUK), Zurich, Switzerland
| | - Sandra E Leh
- Institute for Regenerative Medicine (IREM), University of Zurich, Schlieren, Switzerland
| | - Anton F Gietl
- Institute for Regenerative Medicine (IREM), University of Zurich, Schlieren, Switzerland
| | - Valerie Treyer
- Institute for Regenerative Medicine (IREM), University of Zurich, Schlieren, Switzerland; Department of Nuclear Medicine, University Hospital Zurich, Switzerland
| | - Alfred Buck
- Department of Nuclear Medicine, University Hospital Zurich, Switzerland
| | - Roger M Nitsch
- Institute for Regenerative Medicine (IREM), University of Zurich, Schlieren, Switzerland
| | - Klaas P Pruessmann
- Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Hanzhang Lu
- Neurosection, Division of MRI Research, Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Peter C M Van Zijl
- Neurosection, Division of MRI Research, Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Marilyn Albert
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Christoph Hock
- Institute for Regenerative Medicine (IREM), University of Zurich, Schlieren, Switzerland
| | - Paul G Unschuld
- Institute for Regenerative Medicine (IREM), University of Zurich, Schlieren, Switzerland; Hospital for Psychogeriatric Medicine, Psychiatric University Hospital Zurich (PUK), Zurich, Switzerland.
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Sidorenko I, Turova V, Botkin N, Eckardt L, Alves-Pinto A, Felderhoff-Müser U, Rieger-Fackeldey E, Kovtanyuk A, Lampe R. Modeling Cerebral Blood Flow Dependence on Carbon Dioxide and Mean Arterial Blood Pressure in the Immature Brain With Accounting for the Germinal Matrix. Front Neurol 2018; 9:812. [PMID: 30356709 PMCID: PMC6189337 DOI: 10.3389/fneur.2018.00812] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 09/10/2018] [Indexed: 12/20/2022] Open
Abstract
Intraventricular hemorrhage (IVH) is one of the most critical complications in the development of preterm infants. The likelihood of IVH is strongly associated with disturbances in cerebral blood flow (CBF) and with microvascular fragility in the germinal matrix (GM). The CBF value and its reactivity to changes in arterial carbon dioxide pressure (pCO2) and mean arterial blood pressure (MABP) are relevant indicators in the clinical assessment of preterm infants. The objective of the present study is mathematical modeling of the influence of pCO2 and MABP on CBF in immature brain, based on clinical data collected from 265 preterm infants with 23–30 gestational weeks. The model was adapted to the peculiarities of immature brain by taking into account the morphological characteristics of the GM capillary network and vascular reactivity, according to gestational and postnatal age. An analysis of model based values of CBF and its reactivity to changes in MABP and pCO2 was performed separately for each gestational week and for the first two days of life both for preterm infants with and without IVH. The developed model for the estimation of CBF was validated against equivalent experimental measurements taken from the literature. A good agreement between the estimated values of CBF, as well as its reaction on changes in MABP and pCO2 and the equivalent values obtained in experimental studies was shown.
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Affiliation(s)
- Irina Sidorenko
- Mathematical Faculty, Technical University of Munich, Garching, Germany
| | - Varvara Turova
- Orthopedic Department, University Hospital Rechts der Isar, Technical University of Munich, Munich, Germany
| | - Nikolai Botkin
- Mathematical Faculty, Technical University of Munich, Garching, Germany
| | - Laura Eckardt
- Pediatric Department I, Neonatology, Pediatric Intensive Care, Pediatric Neurology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Ana Alves-Pinto
- Orthopedic Department, University Hospital Rechts der Isar, Technical University of Munich, Munich, Germany
| | - Ursula Felderhoff-Müser
- Pediatric Department I, Neonatology, Pediatric Intensive Care, Pediatric Neurology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Esther Rieger-Fackeldey
- Pediatric Department, University Hospital Rechts der Isar, Technical University of Munich, Munich, Germany
| | - Andrey Kovtanyuk
- Orthopedic Department, University Hospital Rechts der Isar, Technical University of Munich, Munich, Germany
| | - Renée Lampe
- Orthopedic Department, University Hospital Rechts der Isar, Technical University of Munich, Munich, Germany
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Hua J, Liu P, Kim T, Donahue M, Rane S, Chen JJ, Qin Q, Kim SG. MRI techniques to measure arterial and venous cerebral blood volume. Neuroimage 2018; 187:17-31. [PMID: 29458187 DOI: 10.1016/j.neuroimage.2018.02.027] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 02/12/2018] [Accepted: 02/14/2018] [Indexed: 12/14/2022] Open
Abstract
The measurement of cerebral blood volume (CBV) has been the topic of numerous neuroimaging studies. To date, however, most in vivo imaging approaches can only measure CBV summed over all types of blood vessels, including arterial, capillary and venous vessels in the microvasculature (i.e. total CBV or CBVtot). As different types of blood vessels have intrinsically different anatomy, function and physiology, the ability to quantify CBV in different segments of the microvascular tree may furnish information that is not obtainable from CBVtot, and may provide a more sensitive and specific measure for the underlying physiology. This review attempts to summarize major efforts in the development of MRI techniques to measure arterial (CBVa) and venous CBV (CBVv) separately. Advantages and disadvantages of each type of method are discussed. Applications of some of the methods in the investigation of flow-volume coupling in healthy brains, and in the detection of pathophysiological abnormalities in brain diseases such as arterial steno-occlusive disease, brain tumors, schizophrenia, Huntington's disease, Alzheimer's disease, and hypertension are demonstrated. We believe that the continual development of MRI approaches for the measurement of compartment-specific CBV will likely provide essential imaging tools for the advancement and refinement of our knowledge on the exquisite details of the microvasculature in healthy and diseased brains.
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Affiliation(s)
- Jun Hua
- Neurosection, Div. of MRI Research, Dept. of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA.
| | - Peiying Liu
- Neurosection, Div. of MRI Research, Dept. of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Tae Kim
- Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Manus Donahue
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Swati Rane
- Radiology, University of Washington Medical Center, Seattle, WA, USA
| | - J Jean Chen
- Rotman Research Institute, Baycrest Centre, Canada; Department of Medical Biophysics, University of Toronto, Canada
| | - Qin Qin
- Neurosection, Div. of MRI Research, Dept. of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Seong-Gi Kim
- Center for Neuroscience Imaging Research, Institute for Basic Science (IBS), Suwon, South Korea; Department of Biomedical Engineering, Sungkyunkwan University, Suwon, South Korea
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Piechnik SK, Neubauer S, Ferreira VM. State-of-the-art review: stress T1 mapping-technical considerations, pitfalls and emerging clinical applications. MAGMA (NEW YORK, N.Y.) 2018; 31:131-141. [PMID: 28914389 PMCID: PMC5813075 DOI: 10.1007/s10334-017-0649-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 08/21/2017] [Accepted: 08/24/2017] [Indexed: 01/02/2023]
Abstract
In vivo mapping of the myocardial T1 relaxation time has recently attained wide clinical validation of its potential utility. In this review, we address the basic principles of the T1 mapping techniques, with particular attention to the emerging application of vasodilatory stress agents to interrogate the myocardial microvascular compartment, and differences between commonly used T1 mapping methods when applied in clinical practice.
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Affiliation(s)
- Stefan K Piechnik
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, UK.
| | - Stefan Neubauer
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, UK
| | - Vanessa M Ferreira
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, UK
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35
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Peyrounette M, Davit Y, Quintard M, Lorthois S. Multiscale modelling of blood flow in cerebral microcirculation: Details at capillary scale control accuracy at the level of the cortex. PLoS One 2018; 13:e0189474. [PMID: 29324784 PMCID: PMC5764267 DOI: 10.1371/journal.pone.0189474] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 11/28/2017] [Indexed: 11/19/2022] Open
Abstract
Aging or cerebral diseases may induce architectural modifications in human brain microvascular networks, such as capillary rarefaction. Such modifications limit blood and oxygen supply to the cortex, possibly resulting in energy failure and neuronal death. Modelling is key in understanding how these architectural modifications affect blood flow and mass transfers in such complex networks. However, the huge number of vessels in the human brain—tens of billions—prevents any modelling approach with an explicit architectural representation down to the scale of the capillaries. Here, we introduce a hybrid approach to model blood flow at larger scale in the brain microcirculation, based on its multiscale architecture. The capillary bed, which is a space-filling network, is treated as a porous medium and modelled using a homogenized continuum approach. The larger arteriolar and venular trees, which cannot be homogenized because of their fractal-like nature, are treated as a network of interconnected tubes with a detailed representation of their spatial organization. The main contribution of this work is to devise a proper coupling model at the interface between these two components. This model is based on analytical approximations of the pressure field that capture the strong pressure gradients building up in the capillaries connected to arterioles or venules. We evaluate the accuracy of this model for both very simple architectures with one arteriole and/or one venule and for more complex ones, with anatomically realistic tree-like vessels displaying a large number of coupling sites. We show that the hybrid model is very accurate in describing blood flow at large scales and further yields a significant computational gain by comparison with a classical network approach. It is therefore an important step towards large scale simulations of cerebral blood flow and lays the groundwork for introducing additional levels of complexity in the future.
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Affiliation(s)
- Myriam Peyrounette
- Institut de Mécanique des Fluides de Toulouse, IMFT, Université de Toulouse, CNRS - Toulouse, France
| | - Yohan Davit
- Institut de Mécanique des Fluides de Toulouse, IMFT, Université de Toulouse, CNRS - Toulouse, France
| | - Michel Quintard
- Institut de Mécanique des Fluides de Toulouse, IMFT, Université de Toulouse, CNRS - Toulouse, France
| | - Sylvie Lorthois
- Institut de Mécanique des Fluides de Toulouse, IMFT, Université de Toulouse, CNRS - Toulouse, France
- Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, United States of America
- * E-mail:
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36
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Botkin ND, Kovtanyuk AE, Turova VL, Sidorenko IN, Lampe R. Direct modeling of blood flow through the vascular network of the germinal matrix. Comput Biol Med 2018; 92:147-155. [DOI: 10.1016/j.compbiomed.2017.11.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 10/16/2017] [Accepted: 11/13/2017] [Indexed: 10/18/2022]
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Piechnik SK, Jerosch-Herold M. Myocardial T1 mapping and extracellular volume quantification: an overview of technical and biological confounders. Int J Cardiovasc Imaging 2017; 34:3-14. [PMID: 28849419 PMCID: PMC5851695 DOI: 10.1007/s10554-017-1235-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 08/10/2017] [Indexed: 11/24/2022]
Abstract
Novel tissue biomarkers based on the spin–lattice relaxation time T1, a fundamental property in the theory of magnetic resonance physics, have emerged as a new approach for myocardial tissue characterization with many validated clinical applications. This article is intended as an overview of the physical and physiological mechanisms underlying the interpretation and the accuracy of any practical measurement of T1, or derived biomarkers such as extravascular volume fraction, and also includes a discussion of potential pitfalls. Numerous caveats und knowledge gaps related to the precise interpretation of T1-based biomarkers remain, which are being addressed incrementally through ongoing research. Equally important, further careful standardization will pave the way for a wider clinical translation of these novel T1-based biomarkers of tissue remodeling, which have been well validated for their sensitivity to pathophysiological changes, though for the most part in single-center studies.
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Affiliation(s)
- Stefan K Piechnik
- Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX39DU, UK
| | - Michael Jerosch-Herold
- Brigham and Women's Hospital, and Harvard Medical School, 15 Francis Street, Boston, MA, 02115, USA.
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38
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Voss HU, Dyke JP, Tabelow K, Schiff ND, Ballon DJ. Magnetic resonance advection imaging of cerebrovascular pulse dynamics. J Cereb Blood Flow Metab 2017; 37:1223-1235. [PMID: 27221244 PMCID: PMC5453446 DOI: 10.1177/0271678x16651449] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We analyze the pulsatile signal component of dynamic echo planar imaging data from the brain by modeling the dependence between local temporal and spatial signal variability. The resulting magnetic resonance advection imaging maps depict the location of major arteries. Color direction maps allow for visualization of the direction of blood vessels. The potential significance of magnetic resonance advection imaging maps is demonstrated on a functional magnetic resonance imaging data set of 19 healthy subjects. A comparison with the here introduced pulse coherence maps, in which the echo planar imaging signal is correlated with a cardiac pulse signal, shows that the magnetic resonance advection imaging approach results in a better spatial definition without the need for a pulse reference. In addition, it is shown that magnetic resonance advection imaging velocities can be estimates of pulse wave velocities if certain requirements are met, which are specified. Although for this application magnetic resonance advection imaging velocities are not quantitative estimates of pulse wave velocities, they clearly depict local pulsatile dynamics. Magnetic resonance advection imaging can be applied to existing dynamic echo planar imaging data sets with sufficient spatiotemporal resolution. It is discussed whether magnetic resonance advection imaging might have the potential to evolve into a biomarker for the health of the cerebrovascular system.
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Affiliation(s)
- Henning U Voss
- 1 Department of Radiology, Citigroup Biomedical Imaging Center, Weill Cornell Medicine, New York, NY, USA
| | - Jonathan P Dyke
- 1 Department of Radiology, Citigroup Biomedical Imaging Center, Weill Cornell Medicine, New York, NY, USA
| | - Karsten Tabelow
- 2 Weierstrass Institute for Applied Analysis and Stochastics, Berlin, Germany
| | - Nicholas D Schiff
- 3 Department of Neurology and Neuroscience, Weill Cornell Medicine, New York, NY, USA
| | - Douglas J Ballon
- 1 Department of Radiology, Citigroup Biomedical Imaging Center, Weill Cornell Medicine, New York, NY, USA
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39
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Yang T, Sun Y, Lu Z, Leak RK, Zhang F. The impact of cerebrovascular aging on vascular cognitive impairment and dementia. Ageing Res Rev 2017; 34:15-29. [PMID: 27693240 DOI: 10.1016/j.arr.2016.09.007] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 08/09/2016] [Accepted: 09/26/2016] [Indexed: 02/07/2023]
Abstract
As human life expectancy rises, the aged population will increase. Aging is accompanied by changes in tissue structure, often resulting in functional decline. For example, aging within blood vessels contributes to a decrease in blood flow to important organs, potentially leading to organ atrophy and loss of function. In the central nervous system, cerebral vascular aging can lead to loss of the integrity of the blood-brain barrier, eventually resulting in cognitive and sensorimotor decline. One of the major of types of cognitive dysfunction due to chronic cerebral hypoperfusion is vascular cognitive impairment and dementia (VCID). In spite of recent progress in clinical and experimental VCID research, our understanding of vascular contributions to the pathogenesis of VCID is still very limited. In this review, we summarize recent findings on VCID, with a focus on vascular age-related pathologies and their contribution to the development of this condition.
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Affiliation(s)
- Tuo Yang
- Department of Neurology, Pittsburgh Institute of Brain Disorders and Recovery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Yang Sun
- Department of Neurology, Pittsburgh Institute of Brain Disorders and Recovery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Zhengyu Lu
- Department of Neurology, Pittsburgh Institute of Brain Disorders and Recovery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; Department of Neurology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese, Shanghai 200437, China
| | - Rehana K Leak
- Division of Pharmaceutical Sciences, Mylan School of Pharmacy, Duquesne University, Pittsburgh, PA 15282, USA
| | - Feng Zhang
- Department of Neurology, Pittsburgh Institute of Brain Disorders and Recovery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA; Key Lab of Cerebral Microcirculation in Universities of Shandong, Taishan Medical University, Taian, Shandong, 271000, China.
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40
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Crescenzi R, Donahue PMC, Hartley KG, Desai AA, Scott AO, Braxton V, Mahany H, Lants SK, Donahue MJ. Lymphedema evaluation using noninvasive 3T MR lymphangiography. J Magn Reson Imaging 2017; 46:1349-1360. [PMID: 28245075 DOI: 10.1002/jmri.25670] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 01/30/2017] [Indexed: 01/05/2023] Open
Abstract
PURPOSE To exploit the long 3.0T relaxation times and low flow velocity of lymphatic fluid to develop a noninvasive 3.0T lymphangiography sequence and evaluate its relevance in patients with lymphedema. MATERIALS AND METHODS A 3.0T turbo-spin-echo (TSE) pulse train with long echo time (TEeffective = 600 msec; shot-duration = 13.2 msec) and TSE-factor (TSE-factor = 90) was developed and signal evolution simulated. The method was evaluated in healthy adults (n = 11) and patients with unilateral breast cancer treatment-related lymphedema (BCRL; n = 25), with a subgroup (n = 5) of BCRL participants scanned before and after manual lymphatic drainage (MLD) therapy. Maximal lymphatic vessel cross-sectional area, signal-to-noise-ratio (SNR), and results from a five-point categorical scoring system were recorded. Nonparametric tests were applied to evaluate study parameter differences between controls and patients, as well as between affected and contralateral sides in patients (significance criteria: two-sided P < 0.05). RESULTS Patient volunteers demonstrated larger lymphatic cross-sectional areas in the affected (arm = 12.9 ± 6.3 mm2 ; torso = 17.2 ± 15.6 mm2 ) vs. contralateral (arm = 9.4 ± 3.9 mm2 ; torso = 9.1 ± 4.6 mm2 ) side; this difference was significant both for the arm (P = 0.014) and torso (P = 0.025). Affected (arm: P = 0.010; torso: P = 0.016) but not contralateral (arm: P = 0.42; torso: P = 0.71) vessel areas were significantly elevated compared with control values. Lymphatic cross-sectional areas reduced following MLD on the affected side (pre-MLD: arm = 8.8 ± 1.8 mm2 ; torso = 31.4 ± 26.0 mm2 ; post-MLD: arm = 6.6 ± 1.8 mm2 ; torso = 23.1 ± 24.3 mm2 ). This change was significant in the torso (P = 0.036). The categorical scoring was found to be less specific for detecting lateralizing disease compared to lymphatic-vessel areas. CONCLUSION A 3.0T lymphangiography sequence is proposed, which allows for upper extremity lymph stasis to be detected in ∼10 minutes without exogenous contrast agents. LEVEL OF EVIDENCE 1 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:1349-1360.
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Affiliation(s)
- Rachelle Crescenzi
- Radiology and Radiological Science, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Paula M C Donahue
- Physical Medicine and Rehabilitation, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.,Dayani Center for Health and Wellness, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Katherine G Hartley
- Radiology and Radiological Science, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Aditi A Desai
- Radiology and Radiological Science, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Allison O Scott
- Radiology and Radiological Science, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Vaughn Braxton
- Radiology and Radiological Science, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Helen Mahany
- Radiology and Radiological Science, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Sarah K Lants
- Radiology and Radiological Science, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Manus J Donahue
- Radiology and Radiological Science, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.,Neurology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.,Psychiatry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.,Physics and Astronomy, Vanderbilt University, Nashville, Tennessee, USA
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41
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C. Arciero J, Causin P, Malgaroli F. Mathematical methods for modeling the microcirculation. AIMS BIOPHYSICS 2017. [DOI: 10.3934/biophy.2017.3.362] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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42
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Liu D, Xu F, Lin DD, van Zijl PCM, Qin Q. Quantitative measurement of cerebral blood volume using velocity-selective pulse trains. Magn Reson Med 2016; 77:92-101. [PMID: 27797101 DOI: 10.1002/mrm.26515] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 09/26/2016] [Accepted: 09/26/2016] [Indexed: 12/20/2022]
Abstract
PURPOSE To develop a non-contrast-enhanced MRI method for cerebral blood volume (CBV) mapping using velocity-selective (VS) pulse trains. METHODS The new pulse sequence applied velocity-sensitive gradient waveforms in the VS label modules and velocity-compensated ones in the control scans. Sensitivities to the gradient imperfections (e.g., eddy currents) were evaluated through phantom studies. CBV quantification procedures based on simulated labeling efficiencies for arteriolar, capillary, and venular blood as a function of cutoff velocity (Vc) are presented. Experiments were conducted on healthy volunteers at 3T to examine the effects of unbalanced diffusion weighting, cerebrospinal (CSF) contamination and variation of Vc. RESULTS Phantom results of the used VS pulse trains demonstrated robustness to eddy currents. The mean CBV values of gray matter and white matter for the experiments using Vc = 3.5 mm/s and velocity-compensated control with CSF-nulling were 5.1 ± 0.6 mL/100 g and 2.4 ± 0.2 mL/100 g, respectively, which were 23% and 32% lower than results from the experiment with velocity-insensitive control, corresponding to 29% and 25% lower in averaged temporal signal-to-noise ratio values. CONCLUSION A novel technique using VS pulse trains was demonstrated for CBV mapping. The results were both qualitatively and quantitatively close to those from existing methods. Magn Reson Med 77:92-101, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Dexiang Liu
- Department of Radiology, Panyu District Central Hospital, Guangzhou, Guangdong Province, China.,The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Feng Xu
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Doris D Lin
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Peter C M van Zijl
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
| | - Qin Qin
- The Russell H. Morgan Department of Radiology and Radiological Science, Division of MR Research, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA
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43
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Schmid S, Petersen ET, Van Osch MJP. Insight into the labeling mechanism of acceleration selective arterial spin labeling. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2016; 30:165-174. [PMID: 27787676 PMCID: PMC5364255 DOI: 10.1007/s10334-016-0596-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 10/11/2016] [Accepted: 10/13/2016] [Indexed: 11/21/2022]
Abstract
Objectives Acceleration selective arterial spin labeling (AccASL) is a spatially non-selective labeling technique, used in traditional ASL methods, which labels spins based on their flow acceleration rather than spatial localization. The exact origin of the AccASL signal within the vasculature is not completely understood. To obtain more insight into this, the acceleration selective module was performed followed by a velocity selective module, which is used in velocity selective arterial spin labeling (VS-ASL). Materials and methods Nine healthy volunteers were scanned with various combinations of the control and label conditions in both the acceleration and velocity selective module. The cut-off acceleration (0.59 m/s2) or velocity (2 cm/s) was kept constant in one module, while it was varied over a large range in the other module. With the right subtractions this resulted in AccASL, VS-ASL, combined AccASL and VS-ASL signal, and signal from one module with crushing from the other. Results The label created with AccASL has an overlap of approximately 50% in the vascular region with VS-ASL, but also originates from smaller vessels closer to the capillaries. Conclusion AccASL is able to label spins both in the macro- and meso-vasculature, as well as in the microvasculature. Electronic supplementary material The online version of this article (doi:10.1007/s10334-016-0596-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sophie Schmid
- Department of Radiology, C.J. Gorter Center for High Field MRI, Leiden University Medical Center, C3-Q, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands.
| | - Esben T Petersen
- Danish Research Centre for Magnetic Resonance, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark
| | - Matthias J P Van Osch
- Department of Radiology, C.J. Gorter Center for High Field MRI, Leiden University Medical Center, C3-Q, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands.,Leiden Institute for Brain and Cognition, Leiden, The Netherlands
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44
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Donahue MJ, Juttukonda MR, Watchmaker JM. Noise concerns and post-processing procedures in cerebral blood flow (CBF) and cerebral blood volume (CBV) functional magnetic resonance imaging. Neuroimage 2016; 154:43-58. [PMID: 27622397 DOI: 10.1016/j.neuroimage.2016.09.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 08/22/2016] [Accepted: 09/03/2016] [Indexed: 01/19/2023] Open
Abstract
Functional neuroimaging with blood oxygenation level-dependent (BOLD) contrast has emerged as the most popular method for evaluating qualitative changes in brain function in humans. At typical human field strengths (1.5-3.0T), BOLD contrast provides a measure of changes in transverse water relaxation rates in and around capillary and venous blood, and as such provides only a surrogate marker of brain function that depends on dynamic changes in hemodynamics (e.g., cerebral blood flow and volume) and metabolism (e.g., oxygen extraction fraction and the cerebral metabolic rate of oxygen consumption). Alternative functional neuroimaging methods that are specifically sensitive to these constituents of the BOLD signal are being developed and applied in a growing number of clinical and neuroscience applications of quantitative cerebral physiology. These methods require additional considerations for interpreting and quantifying their contrast responsibly. Here, an overview of two popular methods, arterial spin labeling and vascular space occupancy, is presented specifically in the context of functional neuroimaging. Appropriate post-processing and experimental acquisition strategies are summarized with the motivation of reducing sensitivity to noise and unintended signal sources and improving quantitative accuracy of cerebral hemodynamics.
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Affiliation(s)
- Manus J Donahue
- Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Nashville, TN, USA; Neurology, Vanderbilt University School of Medicine, Nashville, TN, USA; Psychiatry, Vanderbilt University School of Medicine, Nashville, TN, USA.
| | - Meher R Juttukonda
- Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Jennifer M Watchmaker
- Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Nashville, TN, USA
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Mikhail Kellawan J, Harrell JW, Schrauben EM, Hoffman CA, Roldan-Alzate A, Schrage WG, Wieben O. Quantitative cerebrovascular 4D flow MRI at rest and during hypercapnia challenge. Magn Reson Imaging 2016; 34:422-8. [DOI: 10.1016/j.mri.2015.12.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 12/13/2015] [Indexed: 12/01/2022]
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Liu A, Wijesurendra RS, Francis JM, Robson MD, Neubauer S, Piechnik SK, Ferreira VM. Adenosine Stress and Rest T1 Mapping Can Differentiate Between Ischemic, Infarcted, Remote, and Normal Myocardium Without the Need for Gadolinium Contrast Agents. JACC Cardiovasc Imaging 2015; 9:27-36. [PMID: 26684978 PMCID: PMC4708879 DOI: 10.1016/j.jcmg.2015.08.018] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 08/25/2015] [Accepted: 08/27/2015] [Indexed: 01/10/2023]
Abstract
Objectives The aim of this study was to evaluate the potential of T1 mapping at rest and during adenosine stress as a novel method for ischemia detection without the use of gadolinium contrast. Background In chronic coronary artery disease (CAD), accurate detection of ischemia is important because targeted revascularization improves clinical outcomes. Myocardial blood volume (MBV) may be a more comprehensive marker of ischemia than myocardial blood flow. T1 mapping using cardiac magnetic resonance (CMR) is highly sensitive to changes in myocardial water content, including MBV. We propose that T1 mapping at rest and during adenosine vasodilatory stress can detect MBV changes in normal and diseased myocardium in CAD. Methods Twenty normal controls (10 at 1.5-T; 10 at 3.0-T) and 10 CAD patients (1.5-T) underwent conventional CMR to assess for left ventricular function (cine), infarction (late gadolinium enhancement [LGE]) and ischemia (myocardial perfusion reserve index [MPRI] on first-pass perfusion imaging during adenosine stress). These were compared to novel pre-contrast stress/rest T1 mapping using the Shortened Modified Look-Locker Inversion recovery technique, which is heart rate independent. T1 values were derived for normal myocardium in controls and for infarcted, ischemic, and remote myocardium in CAD patients. Results Normal myocardium in controls (normal wall motion, MPRI, no LGE) showed normal resting T1 (954 ± 19 ms at 1.5-T; 1,189 ± 34 ms at 3.0-T) and significant positive T1 reactivity during adenosine stress compared to baseline (6.2 ± 0.5% at 1.5-T; 6.3 ± 1.1% at 3.0-T; all p < 0.0001). Infarcted myocardium showed the highest resting T1 of all tissue classes (1,442 ± 84 ms), without significant T1 reactivity (0.2 ± 1.5%). Ischemic myocardium showed elevated resting T1 compared to normal (987 ± 17 ms; p < 0.001) without significant T1 reactivity (0.2 ± 0.8%). Remote myocardium, although having comparable resting T1 to normal (955 ± 17 ms; p = 0.92), showed blunted T1 reactivity (3.9 ± 0.6%; p < 0.001). Conclusions T1 mapping at rest and during adenosine stress can differentiate between normal, infarcted, ischemic, and remote myocardium with distinctive T1 profiles. Stress/rest T1 mapping holds promise for ischemia detection without the need for gadolinium contrast.
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Affiliation(s)
- Alexander Liu
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Rohan S Wijesurendra
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Jane M Francis
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Matthew D Robson
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Stefan Neubauer
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Stefan K Piechnik
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Vanessa M Ferreira
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom.
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Sun H, Fessler JA, Noll DC, Nielsen JF. Steady-state functional MRI using spoiled small-tip fast recovery imaging. Magn Reson Med 2015; 73:536-43. [PMID: 24619593 PMCID: PMC4426392 DOI: 10.1002/mrm.25146] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2013] [Revised: 12/29/2013] [Accepted: 01/03/2014] [Indexed: 11/09/2022]
Abstract
PURPOSE To determine whether a recently proposed steady-state magnetic resonance imaging (MRI) sequence, "small-tip fast recovery" (STFR), can be used for functional brain imaging. Compared to existing functional MRI (fMRI) based on T2*-contrast and long echo time, STFR has the potential for high-resolution imaging with reduced B0 artifacts such as geometric distortions, blurring, or local signal dropout. METHODS We used Monte Carlo Bloch simulations to calculate the voxel-averaged steady-state signal during rest and activation, for blood oxygen level dependent (BOLD) and STFR. STFR relies on a tailored "tip-up" radiofrequency pulse to align the spins with the longitudinal axis after each data readout segment, and here we performed proof-of-concept in vivo STFR fMRI experiments using a tip-up pulse tailored to a two-dimensional region-of-interest in motor cortex. Experiments were performed on multiple subjects to test reliability of the functional activation maps. RESULTS Bloch simulations predict a detectable functional signal that depends mainly on intravoxel dephasing, and only weakly on spin diffusion. STFR produces similar activation maps and signal change as BOLD in finger-tapping experiments, and shows reliability comparable to BOLD. CONCLUSION STFR can produce functional contrast (even with short TE), and is a potential alternative to long-TE ( T2*) fMRI. The functional contrast arises primarily from the interaction between T2*-like dephasing and the tailored tip-up pulse, and not from spin diffusion.
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Affiliation(s)
- Hao Sun
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, USA
| | - Jeffrey A. Fessler
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, USA
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Douglas C. Noll
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Jon-Fredrik Nielsen
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
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Ocwieja M, Meiser K, David OJ, Valencia J, Wagner F, Schreiber SJ, Pleyer U, Ziemer S, Schmouder R. Effect of fingolimod (FTY720) on cerebral blood flow, platelet function and macular thickness in healthy volunteers. Br J Clin Pharmacol 2014; 78:1354-65. [PMID: 24976291 PMCID: PMC4256624 DOI: 10.1111/bcp.12454] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Accepted: 06/23/2014] [Indexed: 12/16/2022] Open
Abstract
AIM Fingolimod, a sphingosine 1-phosphate receptor modulator, is the first oral disease modifying therapy approved for the treatment of relapsing multiple sclerosis. The aim of this double-blind, placebo-controlled study was to evaluate the effect of fingolimod on cerebral blood flow, platelet function and macular thickness in healthy volunteers. METHODS The study included 88 healthy volunteers who received fingolimod 0.5 mg or 1.25 mg or matched placebo over a period of 4 weeks. Transcranial colour coded sonography was performed to measure mean blood flow velocities, the platelet function was measured by the PFA-100® assay using a collagen/epinephrine cartridge and macular thickness was measured using optical coherence tomography. An assessment of non-inferiority of fingolimod vs. placebo was performed against a reference value (20% of the overall baseline value). RESULTS All 88 randomized participants completed the study. At day 28 compared with baseline value, for 0.5 mg, 1.25 mg and placebo treatments, the mean middle cerebral artery blood flow velocity decreased by 4, 1 and 3.7 cm s(-1), respectively. The platelet function analyzer closure time increase was not significant (7.8, 7.5 and 10.4 s, respectively). The mean percentage change in the central foveal thickness from baseline for both eyes was below 3% for all groups. The safety profile of fingolimod in this study was found consistent with the previous reports. CONCLUSIONS In healthy volunteers, the changes seen with both fingolimod doses were found to be within normal variability, non-inferior and comparable with those observed with placebo for all the pharmacodynamic parameters assessed.
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Affiliation(s)
| | | | | | | | - Frank Wagner
- Charité Research Organisation GmbHCharitéplatz 1, Berlin, Germany
| | - Stephan J Schreiber
- Department of Neurology, Universitätsmedizin BerlinCharitéplatz 1, Berlin, Germany
- Department of Neurology, Charité UniversitätsmedizinCharitéplatz 1, Berlin, Germany
| | - Uwe Pleyer
- Department of Ophthalmology, Universitätsmedizin BerlinAugustenburger Platz 1, Berlin, Germany
- Department of Ophthalmology, Charité UniversitätsmedizinCharitéplatz 1, Berlin, Germany
| | - Sabine Ziemer
- Institute for Laboratory Medicine, Clinical Chemistry and Pathobiochemistry, Universitätsmedizin BerlinCharitéplatz 1, Berlin, Germany
- Coagulation Laboratory, Charité UniversitätsmedizinCharitéplatz 1, Berlin, Germany
| | - Robert Schmouder
- Novartis Institutes for Biomedical Research, Inc.Massachusetts Avenue, Cambridge, MA, USA
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Mahmod M, Piechnik SK, Levelt E, Ferreira VM, Francis JM, Lewis A, Pal N, Dass S, Ashrafian H, Neubauer S, Karamitsos TD. Adenosine stress native T1 mapping in severe aortic stenosis: evidence for a role of the intravascular compartment on myocardial T1 values. J Cardiovasc Magn Reson 2014; 16:92. [PMID: 25410203 PMCID: PMC4237748 DOI: 10.1186/s12968-014-0092-y] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 11/04/2014] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Myocardial T1 relaxation times have been reported to be markedly abnormal in diverse myocardial pathologies, ascribed to interstitial changes, evaluated by T1 mapping and calculation of extracellular volume (ECV). T1 mapping is sensitive to myocardial water content of both intra- and extracellular in origin, but the effect of intravascular compartment changes on T1 has been largely neglected. We aimed to assess the role of intravascular compartment on native (pre-contrast) T1 values by studying the effect of adenosine-induced vasodilatation in patients with severe aortic stenosis (AS) before and after aortic valve replacement (AVR). METHODS 42 subjects (26 patients with severe AS without obstructive coronary artery disease and 16 controls) underwent cardiovascular magnetic resonance at 3 T for native T1-mapping (ShMOLLI), first-pass perfusion (myocardial perfusion reserve index-MPRI) at rest and during adenosine stress, and late gadolinium enhancement (LGE). RESULTS AS patients had increased resting myocardial T1 (1196±47 ms vs. 1168±27 ms, p=0.037), reduced MPRI (0.92±0.31 vs. 1.74±0.32, p<0.001), and increased left ventricular mass index (LVMI) and LGE volume compared to controls. During adenosine stress, T1 in AS was similar to controls (1240±51 ms vs. 1238±54 ms, p=0.88), possibly reflecting a similar level of maximal coronary vasodilatation in both groups. Conversely, the T1 response to stress was blunted in AS (ΔT1 3.7±2.7% vs. 6.0±4.2% in controls, p=0.013). Seven months after AVR (n=16) myocardial T1 and response to adenosine stress recovered towards normal. Native T1 values correlated with reduced MPRI, aortic valve area, and increased LVMI. CONCLUSIONS Our study suggests that native myocardial T1 values are not only influenced by interstitial and intracellular water changes, but also by changes in the intravascular compartment. Performing T1 mapping during or soon after vasodilator stress may affect ECV measurements given that hyperemia alone appears to substantially alter T1 values.
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Affiliation(s)
- Masliza Mahmod
- />University of Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, John Radcliffe Hospital, Oxford, OX3 9DU UK
| | - Stefan K Piechnik
- />University of Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, John Radcliffe Hospital, Oxford, OX3 9DU UK
| | - Eylem Levelt
- />University of Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, John Radcliffe Hospital, Oxford, OX3 9DU UK
| | - Vanessa M Ferreira
- />University of Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, John Radcliffe Hospital, Oxford, OX3 9DU UK
| | - Jane M Francis
- />University of Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, John Radcliffe Hospital, Oxford, OX3 9DU UK
| | - Andrew Lewis
- />University of Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, John Radcliffe Hospital, Oxford, OX3 9DU UK
| | - Nikhil Pal
- />University of Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, John Radcliffe Hospital, Oxford, OX3 9DU UK
| | - Sairia Dass
- />University of Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, John Radcliffe Hospital, Oxford, OX3 9DU UK
| | - Houman Ashrafian
- />University of Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, John Radcliffe Hospital, Oxford, OX3 9DU UK
| | - Stefan Neubauer
- />University of Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, John Radcliffe Hospital, Oxford, OX3 9DU UK
| | - Theodoros D Karamitsos
- />University of Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, John Radcliffe Hospital, Oxford, OX3 9DU UK
- />1st Department of Cardiology, AHEPA Hospital, Aristotle University of Thessaloniki, Thessaloniki, 54636 Greece
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Mathematical modelling of cerebral blood circulation and cerebral autoregulation: towards preventing intracranial hemorrhages in preterm newborns. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2014; 2014:965275. [PMID: 25126111 PMCID: PMC4122005 DOI: 10.1155/2014/965275] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 06/20/2014] [Accepted: 06/20/2014] [Indexed: 11/22/2022]
Abstract
Impaired cerebral autoregulation leads to fluctuations in cerebral blood flow, which can be especially dangerous for immature brain of preterm newborns. In this paper, two mathematical models of cerebral autoregulation are discussed. The first one is an enhancement of a vascular model proposed by Piechnik et al. We extend this model by adding a polynomial dependence of the vascular radius on the arterial blood pressure and adjusting the polynomial coefficients to experimental data to gain the autoregulation behavior. Moreover, the inclusion of a Preisach hysteresis operator, simulating a hysteretic dependence of the cerebral blood flow on the arterial pressure, is tested. The second model couples the blood vessel system model by Piechnik et al. with an ordinary differential equation model of cerebral autoregulation by Ursino and Lodi. An optimal control setting is proposed for a simplified variant of this coupled model. The objective of the control is the maintenance of the autoregulatory function for a wider range of the arterial pressure. The control can be interpreted as the effect of a medicament changing the cerebral blood flow by, for example, dilation of blood vessels. Advanced numerical methods developed by the authors are applied for the numerical treatment of the control problem.
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