Pub Date : 2012-05-03DOI: 10.2174/1874347101206010062
Yosuke Hashimoto, S. Yokoyama, R. Kawashima
While a clear variability of canonical word order across languages has been found, such a finding is not reflected in recent neuroimaging studies of language processing. Languages having a canonical word order of Subject- Object-Verb (SOV) in a sentence make up approximately 43% of world languages, while languages having a Subject- Verb-Object (SVO) word order make up approximately 37%. Sufficient attention has not been given to this typological difference in neuroimaging studies. In this article, we review neuroimaging studies of sentence processing to examine whether the typological difference of canonical word order in a sentence is represented in brain activation results or not. As a result of this literature survey, an effect from the difference in canonical word order was found to exist between SVO and SOV languages for brain activation during sentence comprehension. This effect was found mainly in the left inferior and middle frontal gyri, precentral gyrus, supplemental motor area, inferior and middle temporal gyri, temporal pole, hippocampus, and cerebellum. These results imply that a difference in canonical word order causes a different sentence processing pattern, as well as a different load in the working memory process.
{"title":"Neurotypology of Sentence Comprehension: Cross-Linguistic Difference in Canonical Word Order Affects Brain Responses during Sentence Comprehension","authors":"Yosuke Hashimoto, S. Yokoyama, R. Kawashima","doi":"10.2174/1874347101206010062","DOIUrl":"https://doi.org/10.2174/1874347101206010062","url":null,"abstract":"While a clear variability of canonical word order across languages has been found, such a finding is not reflected in recent neuroimaging studies of language processing. Languages having a canonical word order of Subject- Object-Verb (SOV) in a sentence make up approximately 43% of world languages, while languages having a Subject- Verb-Object (SVO) word order make up approximately 37%. Sufficient attention has not been given to this typological difference in neuroimaging studies. In this article, we review neuroimaging studies of sentence processing to examine whether the typological difference of canonical word order in a sentence is represented in brain activation results or not. As a result of this literature survey, an effect from the difference in canonical word order was found to exist between SVO and SOV languages for brain activation during sentence comprehension. This effect was found mainly in the left inferior and middle frontal gyri, precentral gyrus, supplemental motor area, inferior and middle temporal gyri, temporal pole, hippocampus, and cerebellum. These results imply that a difference in canonical word order causes a different sentence processing pattern, as well as a different load in the working memory process.","PeriodicalId":90366,"journal":{"name":"The open medical imaging journal","volume":"12 1","pages":"62-69"},"PeriodicalIF":0.0,"publicationDate":"2012-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77075174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-05-03DOI: 10.2174/1874347101206010047
Ina Bornkessel-Schlesewsky, Matthias Schlesewsky
Since language necessarily unfolds over time, language comprehension involves the processing of a sequentially ordered input. In this paper, we review neuroimaging findings on syntactic processing and word order variations in order to shed light on the neural bases of linguistic sequencing, focusing particularly on the role of prefrontal cortex (including Broca's region). On the basis of the full range of available data from several languages, we argue that different types of sequencing cues correlate with activation along an anterior-posterior gradient in frontal cortex, with highly local sequencing cues eliciting activation in the most posterior frontal regions (premotor cortex and the cytoarchitectonically corresponding frontal operculum) and less local sequencing cues (requiring relational comparisons between the current input element and the current sentence or discourse context, respectively) engendering activation in successively more anterior regions of the left inferior frontal gyrus. We argue that this neurocognitive gradient of linguistic sequence processing can be associated with a more general hierarchy of cognitive control in prefrontal cortex, which has also been shown to vary along an anterior-posterior gradient (1). We conclude that the processing of linguistic sequences and the concomitant extraction of information (e.g. semantic relations) from them, as an essential component of language processing, follows more general principles of neurocognitive organisation in prefrontal cortex.
{"title":"Linguistic Sequence Processing and the Prefrontal Cortex","authors":"Ina Bornkessel-Schlesewsky, Matthias Schlesewsky","doi":"10.2174/1874347101206010047","DOIUrl":"https://doi.org/10.2174/1874347101206010047","url":null,"abstract":"Since language necessarily unfolds over time, language comprehension involves the processing of a sequentially ordered input. In this paper, we review neuroimaging findings on syntactic processing and word order variations in order to shed light on the neural bases of linguistic sequencing, focusing particularly on the role of prefrontal cortex (including Broca's region). On the basis of the full range of available data from several languages, we argue that different types of sequencing cues correlate with activation along an anterior-posterior gradient in frontal cortex, with highly local sequencing cues eliciting activation in the most posterior frontal regions (premotor cortex and the cytoarchitectonically corresponding frontal operculum) and less local sequencing cues (requiring relational comparisons between the current input element and the current sentence or discourse context, respectively) engendering activation in successively more anterior regions of the left inferior frontal gyrus. We argue that this neurocognitive gradient of linguistic sequence processing can be associated with a more general hierarchy of cognitive control in prefrontal cortex, which has also been shown to vary along an anterior-posterior gradient (1). We conclude that the processing of linguistic sequences and the concomitant extraction of information (e.g. semantic relations) from them, as an essential component of language processing, follows more general principles of neurocognitive organisation in prefrontal cortex.","PeriodicalId":90366,"journal":{"name":"The open medical imaging journal","volume":"53 1","pages":"47-61"},"PeriodicalIF":0.0,"publicationDate":"2012-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79902756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-05-03DOI: 10.2174/1874347101206010045
S. Yokoyama
Language is one of the most important higher brain functions for humans. Using medical imaging techniques, such as MRI, PET, MEG, EEG, and NIRS, scientists have been investigating how the brain processes and acquires language. This special issue concerns the processing and acquisition of languages, and the investigations that apply medical imaging techniques to functional brain imaging studies. Hence the purpose of this special issue is to collect articles on studies of language processing and acquisition in humans utilizing medical imaging techniques. This special issue will contribute to uncovering the mechanisms of language processing and acquisition, and also to clarifying some of the questions concerning the clinical aspects of language deficits. APPLICATION OF MEDICAL IMAGING TECHNIQUES TO LANGUAGE STUDIES Language is one of the most important higher brain functions for humans, because in our daily lives we have to live with others and to communicate with them. All humans can acquire at least one language by themselves and can process it, if they have a language environment. Since language processing is conducted in the brain, there is no doubt that medical imaging techniques are highly useful to examine how the brain uses or processes a language. Of course, lesion studies for language have been conducted using medical imaging to see to see how certain brain injuries affect language. However, now we can use medical imaging techniques to not only see brain structures, but also to measure brain activation. This enables us to use brain activation data to investigate how our minds process language. Hence, researchers can use medical imaging techniques, such as functional magnetic resonance imaging (fMRI), positron emission topography (PET), electroencephalography (EEG), magnetoencephalography (MEG), and *Address correspondence to this author at the Department of Functional Brain Imaging, Institute of Development, Aging, and Cancer, Tohoku University, Japan; Tel: +81-22-717-7988; Fax: +81-22-717-7988; E-mail: yokoyama@idac.tohoku.ac.jp near-infrared spectroscopy (NIRs), to measure brain activation patterns during language processing. THE PURPOSE OF THIS SPECIAL ISSUE Because of recent developments in medical imaging techniques, many researchers have applied such techniques to researching human cognitive processes, including language processing. This special issue concerns the processing and acquisition of both one’s mother language and foreign languages, as well as the investigations that apply medical imaging techniques to functional brain imaging studies. Hence, the purpose of this special issue is to collect articles on studies which utilize medical imaging techniques to investigate language processing and acquisition in humans. ARTICLES IN THIS SPECIAL ISSUE This special issue includes two interesting review articles on language processing in the human brain, and one experimental research paper on human language processing using the techniqu
{"title":"Editorial - Application of Medical Imaging Techniques to Studies of Human Language Processing and Acquisition","authors":"S. Yokoyama","doi":"10.2174/1874347101206010045","DOIUrl":"https://doi.org/10.2174/1874347101206010045","url":null,"abstract":"Language is one of the most important higher brain functions for humans. Using medical imaging techniques, such as MRI, PET, MEG, EEG, and NIRS, scientists have been investigating how the brain processes and acquires language. This special issue concerns the processing and acquisition of languages, and the investigations that apply medical imaging techniques to functional brain imaging studies. Hence the purpose of this special issue is to collect articles on studies of language processing and acquisition in humans utilizing medical imaging techniques. This special issue will contribute to uncovering the mechanisms of language processing and acquisition, and also to clarifying some of the questions concerning the clinical aspects of language deficits. APPLICATION OF MEDICAL IMAGING TECHNIQUES TO LANGUAGE STUDIES Language is one of the most important higher brain functions for humans, because in our daily lives we have to live with others and to communicate with them. All humans can acquire at least one language by themselves and can process it, if they have a language environment. Since language processing is conducted in the brain, there is no doubt that medical imaging techniques are highly useful to examine how the brain uses or processes a language. Of course, lesion studies for language have been conducted using medical imaging to see to see how certain brain injuries affect language. However, now we can use medical imaging techniques to not only see brain structures, but also to measure brain activation. This enables us to use brain activation data to investigate how our minds process language. Hence, researchers can use medical imaging techniques, such as functional magnetic resonance imaging (fMRI), positron emission topography (PET), electroencephalography (EEG), magnetoencephalography (MEG), and *Address correspondence to this author at the Department of Functional Brain Imaging, Institute of Development, Aging, and Cancer, Tohoku University, Japan; Tel: +81-22-717-7988; Fax: +81-22-717-7988; E-mail: yokoyama@idac.tohoku.ac.jp near-infrared spectroscopy (NIRs), to measure brain activation patterns during language processing. THE PURPOSE OF THIS SPECIAL ISSUE Because of recent developments in medical imaging techniques, many researchers have applied such techniques to researching human cognitive processes, including language processing. This special issue concerns the processing and acquisition of both one’s mother language and foreign languages, as well as the investigations that apply medical imaging techniques to functional brain imaging studies. Hence, the purpose of this special issue is to collect articles on studies which utilize medical imaging techniques to investigate language processing and acquisition in humans. ARTICLES IN THIS SPECIAL ISSUE This special issue includes two interesting review articles on language processing in the human brain, and one experimental research paper on human language processing using the techniqu","PeriodicalId":90366,"journal":{"name":"The open medical imaging journal","volume":"6 1","pages":"45-46"},"PeriodicalIF":0.0,"publicationDate":"2012-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81996589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-05-03DOI: 10.2174/1874347101206010070
Masatoshi Koizumi, Jungho Kim, Naoki Kimura, S. Yokoyama, Shigeru Sato, K. Horie, R. Kawashima
In order to clarify the relationship among grammatical knowledge, processing components, and neural substrates in sentence comprehension, we used functional magnetic resonance imaging to investigate how brain activation is affected by two types of scrambling (short scrambling and middle scrambling) in ditransitive sentences in Japanese. Short scrambling and middle scrambling enhanced activation in the anterior and posterior left inferior frontal gyrus respectively. This finding accords with the view that the anterior left inferior frontal gyrus is involved in the automatic processing that establishes a dependency relation between a verb and its arguments, and the posterior left inferior frontal gyrus supports this kind of processing through its role in verbal working memory. This result is more congruent with a process-based approach to neural bases for sentence processing, which searches for neurological correlates of psycholinguistically defined processing components, than with a grammar-based approach, which probes neural networks with the assumption that major grammatical operations are neurologically individuated.
{"title":"Left Inferior Frontal Activations Differentially Modulated by Scrambling in Ditransitive Sentences","authors":"Masatoshi Koizumi, Jungho Kim, Naoki Kimura, S. Yokoyama, Shigeru Sato, K. Horie, R. Kawashima","doi":"10.2174/1874347101206010070","DOIUrl":"https://doi.org/10.2174/1874347101206010070","url":null,"abstract":"In order to clarify the relationship among grammatical knowledge, processing components, and neural substrates in sentence comprehension, we used functional magnetic resonance imaging to investigate how brain activation is affected by two types of scrambling (short scrambling and middle scrambling) in ditransitive sentences in Japanese. Short scrambling and middle scrambling enhanced activation in the anterior and posterior left inferior frontal gyrus respectively. This finding accords with the view that the anterior left inferior frontal gyrus is involved in the automatic processing that establishes a dependency relation between a verb and its arguments, and the posterior left inferior frontal gyrus supports this kind of processing through its role in verbal working memory. This result is more congruent with a process-based approach to neural bases for sentence processing, which searches for neurological correlates of psycholinguistically defined processing components, than with a grammar-based approach, which probes neural networks with the assumption that major grammatical operations are neurologically individuated.","PeriodicalId":90366,"journal":{"name":"The open medical imaging journal","volume":"10 1","pages":"70-79"},"PeriodicalIF":0.0,"publicationDate":"2012-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84641434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-04-06DOI: 10.2174/1874347101206010014
Sanjit Peter, G. Beache
Blood oxygenation level-dependent (BOLD) imaging is firmly established as a powerful tool for clinical and research studies in the brain. Though, borrowing from the brain methodology, the technique was early adapted for the heart, due to artifacts unique to myocardial imaging; cardiac and respiratory motion, flow and blood pool effects, and magnetic susceptibility effects arising from the adjacent lungs and bowel, and from the veins at the surface of the heart, cardiac application has largely been limited to research groups. In this paper we aim to focus on these factors affecting ease and reliability of BOLD myocardial imaging, and highlight advances which have the potential to make this methodology more widely accessible to clinicaland physiologybased practioners who may have an interest in exploring this area in collaboration with technical magnetic resonance imaging colleagues
{"title":"BOLD Myocardial Imaging: Advances for Clinical and PhysiologicalApplications","authors":"Sanjit Peter, G. Beache","doi":"10.2174/1874347101206010014","DOIUrl":"https://doi.org/10.2174/1874347101206010014","url":null,"abstract":"Blood oxygenation level-dependent (BOLD) imaging is firmly established as a powerful tool for clinical and research studies in the brain. Though, borrowing from the brain methodology, the technique was early adapted for the heart, due to artifacts unique to myocardial imaging; cardiac and respiratory motion, flow and blood pool effects, and magnetic susceptibility effects arising from the adjacent lungs and bowel, and from the veins at the surface of the heart, cardiac application has largely been limited to research groups. In this paper we aim to focus on these factors affecting ease and reliability of BOLD myocardial imaging, and highlight advances which have the potential to make this methodology more widely accessible to clinicaland physiologybased practioners who may have an interest in exploring this area in collaboration with technical magnetic resonance imaging colleagues","PeriodicalId":90366,"journal":{"name":"The open medical imaging journal","volume":"31 1","pages":"14-17"},"PeriodicalIF":0.0,"publicationDate":"2012-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85417535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-04-06DOI: 10.2174/1874347101206010031
R. Dharmakumar, S. Tsaftaris, Debiao Li
The current state of myocardial Blood-Oxygen-Level-Dependent (BOLD) MRI with balanced steady-state free precession (SSFP) approaches is reviewed. Initial studies forming the basis for SSFP-based detection of oxygenation changes beginning with whole blood studies, progressing through controlled studies that consider microcirculatory changes in oxygenation in skeletal muscle and kidney, culminating in basic myocardial studies are outlined. The theoretical basis to observe signal changes and the mechanisms that facilitate such observations are elucidated. Methods to overcome limitations in sensitivity are described.
{"title":"Myocardial Blood-Oxygen-Level-Dependent Magnetic Resonance Imaging with Balanced Steady-State Free Precession Imaging Approaches","authors":"R. Dharmakumar, S. Tsaftaris, Debiao Li","doi":"10.2174/1874347101206010031","DOIUrl":"https://doi.org/10.2174/1874347101206010031","url":null,"abstract":"The current state of myocardial Blood-Oxygen-Level-Dependent (BOLD) MRI with balanced steady-state free precession (SSFP) approaches is reviewed. Initial studies forming the basis for SSFP-based detection of oxygenation changes beginning with whole blood studies, progressing through controlled studies that consider microcirculatory changes in oxygenation in skeletal muscle and kidney, culminating in basic myocardial studies are outlined. The theoretical basis to observe signal changes and the mechanisms that facilitate such observations are elucidated. Methods to overcome limitations in sensitivity are described.","PeriodicalId":90366,"journal":{"name":"The open medical imaging journal","volume":"22 1","pages":"31-38"},"PeriodicalIF":0.0,"publicationDate":"2012-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82088515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-04-06DOI: 10.2174/1874347101206010012
Jie Zheng
Cardiovascular disease (CVD) remains the number one cause of death in most western countries, and a major cause of hospital admissions. One major disorder of CVD is myocardial ischemia, resulting from upstream coronary artery stenosis or impaired microcirculation. The common clinical manifestations of myocardial ischemia are angina (stable and unstable), myocardial infarction (heart attack), heart failure, arrhythmia (irregular heart beat), and sudden death. The cause of myocardial ischemia is the lack of oxygen-rich blood supply to the myocardial tissue. Balance of myocardial oxygen supply and demand is essential for maintaining the integrity of myocardial metabolism and mechanical function. Strictly speaking, myocardial ischemia is defined by the imbalance of oxygen supply and demand in the myocardial tissue. The assessment of myocardial blood flow is not always adequate to determine whether the tissue is ischemic or not. Conversely, non-invasive assessment of this balance will have a significant clinical impact on the diagnosis and monitoring of cardiac patients with ischemia. Positron emission tomography (PET) has long been recognized as the gold standard for quantifying myocardial oxygenation in terms of myocardial oxygen consumption rate (MVO2) using a
{"title":"Editorial - Non-Invasive Assessment of Myocardial Oxygenation with MRI","authors":"Jie Zheng","doi":"10.2174/1874347101206010012","DOIUrl":"https://doi.org/10.2174/1874347101206010012","url":null,"abstract":"Cardiovascular disease (CVD) remains the number one cause of death in most western countries, and a major cause of hospital admissions. One major disorder of CVD is myocardial ischemia, resulting from upstream coronary artery stenosis or impaired microcirculation. The common clinical manifestations of myocardial ischemia are angina (stable and unstable), myocardial infarction (heart attack), heart failure, arrhythmia (irregular heart beat), and sudden death. The cause of myocardial ischemia is the lack of oxygen-rich blood supply to the myocardial tissue. Balance of myocardial oxygen supply and demand is essential for maintaining the integrity of myocardial metabolism and mechanical function. Strictly speaking, myocardial ischemia is defined by the imbalance of oxygen supply and demand in the myocardial tissue. The assessment of myocardial blood flow is not always adequate to determine whether the tissue is ischemic or not. Conversely, non-invasive assessment of this balance will have a significant clinical impact on the diagnosis and monitoring of cardiac patients with ischemia. Positron emission tomography (PET) has long been recognized as the gold standard for quantifying myocardial oxygenation in terms of myocardial oxygen consumption rate (MVO2) using a","PeriodicalId":90366,"journal":{"name":"The open medical imaging journal","volume":"38 1","pages":"12-13"},"PeriodicalIF":0.0,"publicationDate":"2012-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89579533","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-04-06DOI: 10.2174/1874347101206010039
D. Muccigrosso, Jie Zheng
Myocardial ischemia, resulting from imbalance in myocardial oxygen supply and demand, can be quantitatively assessed by positron emission tomography (PET) with absolute measures of myocardial blood flow and oxygen consumption rate (MVO 2 ). Cardiac Magnetic Resonance (CMR) has notable advantages over PET, with no radiation, high spatial resolution, faster scan times, and excellent soft tissue contrast. We have developed and validated new quantitative CMR oximetry techniques, including measurements of hyperemic myocardial oxygen extraction fraction and MVO 2 through Fick's Law. These may lead to a new understanding of roles of myocardial microcirculation in myocardial ischemia. Other cardiac oximetry methods for directly quantifying MVO 2 with 17 O-labelled water are also under investigation. Quantitative CMR oximetry is a promising, non-invasive, non-radiation approach for exploring the myocardial metabolism's role in cardiac patients.
{"title":"Quantifying Myocardial Oxygenation with Cardiac Magnetic Resonance Imaging","authors":"D. Muccigrosso, Jie Zheng","doi":"10.2174/1874347101206010039","DOIUrl":"https://doi.org/10.2174/1874347101206010039","url":null,"abstract":"Myocardial ischemia, resulting from imbalance in myocardial oxygen supply and demand, can be quantitatively assessed by positron emission tomography (PET) with absolute measures of myocardial blood flow and oxygen consumption rate (MVO 2 ). Cardiac Magnetic Resonance (CMR) has notable advantages over PET, with no radiation, high spatial resolution, faster scan times, and excellent soft tissue contrast. We have developed and validated new quantitative CMR oximetry techniques, including measurements of hyperemic myocardial oxygen extraction fraction and MVO 2 through Fick's Law. These may lead to a new understanding of roles of myocardial microcirculation in myocardial ischemia. Other cardiac oximetry methods for directly quantifying MVO 2 with 17 O-labelled water are also under investigation. Quantitative CMR oximetry is a promising, non-invasive, non-radiation approach for exploring the myocardial metabolism's role in cardiac patients.","PeriodicalId":90366,"journal":{"name":"The open medical imaging journal","volume":"3 1","pages":"39-44"},"PeriodicalIF":0.0,"publicationDate":"2012-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90371687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-04-06DOI: 10.2174/1874347101206010001
Jeff Orchard, H. Kim, J. Yeow
Abstarct: The very hot and power-hungry x-ray filaments in today's computed tomography (CT) scanners constrain their design to be big and stationary. What if we built a CT scanner that could be deployed at the scene of a car accident to acquire tomographic images before moving the victim? Recent developments in nanotechnology have shown that carbon nanotubes can produce x-rays at room temperature, and with relatively low power needs. We propose a design for a portable and flexible CT scanner made up of an addressable array of tiny x-ray emitters and detectors. In this paper, we outline a basic design, propose a strategy for reconstruction, and demonstrate the feasibility of reconstruction using experiments on a software simulation of the flexible scanner. These simulations show that reconstruction quality is stable over a wide range of scanner geometries, while progressively larger errors in the scanner geometry induce progressively larger errors. We also raise a number of issues that still need to be overcome to build such a scanner.
{"title":"Plausibility of Image Reconstruction Using a Proposed Flexible and Portable CT Scanner","authors":"Jeff Orchard, H. Kim, J. Yeow","doi":"10.2174/1874347101206010001","DOIUrl":"https://doi.org/10.2174/1874347101206010001","url":null,"abstract":"Abstarct: The very hot and power-hungry x-ray filaments in today's computed tomography (CT) scanners constrain their design to be big and stationary. What if we built a CT scanner that could be deployed at the scene of a car accident to acquire tomographic images before moving the victim? Recent developments in nanotechnology have shown that carbon nanotubes can produce x-rays at room temperature, and with relatively low power needs. We propose a design for a portable and flexible CT scanner made up of an addressable array of tiny x-ray emitters and detectors. In this paper, we outline a basic design, propose a strategy for reconstruction, and demonstrate the feasibility of reconstruction using experiments on a software simulation of the flexible scanner. These simulations show that reconstruction quality is stable over a wide range of scanner geometries, while progressively larger errors in the scanner geometry induce progressively larger errors. We also raise a number of issues that still need to be overcome to build such a scanner.","PeriodicalId":90366,"journal":{"name":"The open medical imaging journal","volume":"16 1","pages":"1-11"},"PeriodicalIF":0.0,"publicationDate":"2012-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82501846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-04-06DOI: 10.2174/1874347101206010018
N. Ghugre, G. Wright
The purpose of this paper is to present a literature review of the theoretical and experimental work that describes the blood-oxygen-level-dependent or BOLD effect using quantitative T2 relaxation mechanism. The BOLD effect is mediated by paramagnetic deoxyhemoglobin which generates magnetic field inhomogeneities around erythrocytes; T2 is modulated by diffusion of spins in and around erythrocytes. Early work in blood describing the mechanisms of T2 relaxation as a function of oxygen saturation, field strength and cell integrity paved the way towards in vivo determination of tissue oxygenation state. Theoretical modeling in blood and tissue microcirculation further shed light into underlying mechanisms of deoxyhemoglobin, leading the way for interrogating myocardial oxygenation state non invasively. From a clinical standpoint, ongoing pre-clinical studies indicate that quantitative T2 may potentially be more specific than signal intensity measures, allowing regional, longitudinal and cross-subject comparison. Furthermore, the T2-based BOLD technique offers greater sensitivity on a 3T scanner, compared to 1.5T, allowing reliable detection of serial changes in perfusion reserve following acute coronary syndrome. We have thus reviewed the theoretical formulations and experimental observations made over several years by many investigators who have given significant insight into the oxygen-sensitive nature of T2 relaxation in blood and hence into the T2-based BOLD effect in tissue microcirculation.
{"title":"Myocardial BOLD Imaging with T2 Relaxation","authors":"N. Ghugre, G. Wright","doi":"10.2174/1874347101206010018","DOIUrl":"https://doi.org/10.2174/1874347101206010018","url":null,"abstract":"The purpose of this paper is to present a literature review of the theoretical and experimental work that describes the blood-oxygen-level-dependent or BOLD effect using quantitative T2 relaxation mechanism. The BOLD effect is mediated by paramagnetic deoxyhemoglobin which generates magnetic field inhomogeneities around erythrocytes; T2 is modulated by diffusion of spins in and around erythrocytes. Early work in blood describing the mechanisms of T2 relaxation as a function of oxygen saturation, field strength and cell integrity paved the way towards in vivo determination of tissue oxygenation state. Theoretical modeling in blood and tissue microcirculation further shed light into underlying mechanisms of deoxyhemoglobin, leading the way for interrogating myocardial oxygenation state non invasively. From a clinical standpoint, ongoing pre-clinical studies indicate that quantitative T2 may potentially be more specific than signal intensity measures, allowing regional, longitudinal and cross-subject comparison. Furthermore, the T2-based BOLD technique offers greater sensitivity on a 3T scanner, compared to 1.5T, allowing reliable detection of serial changes in perfusion reserve following acute coronary syndrome. We have thus reviewed the theoretical formulations and experimental observations made over several years by many investigators who have given significant insight into the oxygen-sensitive nature of T2 relaxation in blood and hence into the T2-based BOLD effect in tissue microcirculation.","PeriodicalId":90366,"journal":{"name":"The open medical imaging journal","volume":"61 1","pages":"18-30"},"PeriodicalIF":0.0,"publicationDate":"2012-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83765457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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