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Krishnamoorthy S, Surti S. Advances in Breast PET Instrumentation. PET Clin 2024; 19:37-47. [PMID: 37949606 DOI: 10.1016/j.cpet.2023.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
Dedicated breast PET scanners currently have a spatial resolution in the 1.5 to 2 mm range, and the ability to provide tomographic images and quantitative data. They are also commercially available from a few vendors. A review of past and recent advances in the development and performance of dedicated breast PET scanners is summarized.
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Affiliation(s)
- Srilalan Krishnamoorthy
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA.
| | - Suleman Surti
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
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Allen MS, Scipioni M, Catana C. New Horizons in Brain PET Instrumentation. PET Clin 2024; 19:25-36. [PMID: 37806894 PMCID: PMC10840690 DOI: 10.1016/j.cpet.2023.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Dedicated brain PET scanners are optimized to provide high sensitivity and high spatial resolution compared with existing whole-body PET systems, and they can be much cheaper to produce and install in various clinical and research settings. Advancements in detector technology over the past few years have placed several standalone PET, PET/computed tomography, and PET/MR systems on or near the commercial market; the features and capabilities of these systems will be reviewed here.
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Affiliation(s)
- Magdelena S Allen
- Department of Radiology, A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital; Department of Physics, Massachusetts Institute of Technology
| | - Michele Scipioni
- Department of Radiology, A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital; Harvard Medical School
| | - Ciprian Catana
- Department of Radiology, A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital; Harvard Medical School.
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Nitta M, Nishikido F, Inadama N, Hirano Y, Yamaya T. Discrimination of inter-crystal scattering events by signal processing for the X'tal cube PET detector. Radiol Phys Technol 2023; 16:516-531. [PMID: 37782423 DOI: 10.1007/s12194-023-00740-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 08/29/2023] [Accepted: 08/30/2023] [Indexed: 10/03/2023]
Abstract
Inter-crystal scattering (ICS) events cause degradation of the contrast in PET images. We developed the X'tal cube PET detector with submillimeter spatial resolution, which consisted of a segmented LYSO scintillator and 96 MPPCs. For this high spatial resolution PET detector, the ICS event was not negligible. In this study, we proposed a method to discriminate the ICS events and showed its feasibility by the following method. For each 96 MPPC, we measured the mean and standard deviation of the peak in the pulse height distribution obtained by the photoabsorption events in a scintillator pixel. Every time a newly detected event was identified as the segment, we monitored the reduced chi-square value that was calculated with the pulse height and the prepared mean and the standard deviation for each 96 MPPC. Since the pulse height caused by the photoabsorption event resulted in a small reduced chi-square value, we could eliminate the ICS events by setting a threshold on the reduced chi-square value. We carried out both a Monte Carlo simulation and a scanning experiment. By the simulation, we confirmed that the threshold of the reduced chi square significantly discriminated the ICS event. We obtained the response function by a scanning experiment with a 0.2 mm slit beam of 511 keV gamma-ray. The standard deviation of the response function was improved from 1.6 to 1.06 mm by eliminating the ICS events. The proposed method could significantly eliminate the ICS events and retain the true events.
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Affiliation(s)
- Munetaka Nitta
- Faculty of Science, Chiba University, 1-33 Yayoi-Cho, Inage-ku, Chiba, Japan.
- National Institutes of Quantum and Radiological Science and Technology (QST), 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan.
| | - Fumihiko Nishikido
- National Institutes of Quantum and Radiological Science and Technology (QST), 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Naoko Inadama
- National Institutes of Quantum and Radiological Science and Technology (QST), 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Yoshiyuki Hirano
- Graduate School of Medicine, Nagoya University, 65, Tsurumai-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan
| | - Taiga Yamaya
- National Institutes of Quantum and Radiological Science and Technology (QST), 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
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Chen G, Shi Y, Wang R, Ren C, Ng E, Fang X, Ren Z. Integrating weather observations and local-climate-zone-based landscape patterns for regional hourly air temperature mapping using machine learning. Sci Total Environ 2022; 841:156737. [PMID: 35716755 DOI: 10.1016/j.scitotenv.2022.156737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 05/27/2022] [Accepted: 06/12/2022] [Indexed: 06/15/2023]
Abstract
Air temperature is a crucial variable of urban meteorology and is essential to many urban environments, urban climate and climate-change-related studies. However, due to the limited observational records of air temperature and the complex urban morphology and environment, it might not be easy to map the hourly air temperature with a fine resolution at the surface level within and around cities via conventional methods. Thus, this study employed machine learning (ML) algorithms and meteorological and landscape data to develop hourly air temperature mapping techniques and methods at the 1-km resolution over a multi-year warm seasons period. Guangdong Province, China was selected for the case study. Random forest algorithm was employed for the hourly air temperature mapping. The validation results showed that the hourly air temperature maps exhibit good accuracy from 2008 to 2019, with mean R2, root mean square error (RMSE) and mean absolute error (MAE) values of 0.8001, 1.4821 °C and 1.0872 °C, respectively. The importance assessment of the driving factors showed that meteorological factors, especially relative humidity, contributed the most to the air temperature mapping. Simultaneously, landscape factors also played a non-negligible role. Further analysis revealed that the maps steadily maintained high accuracy at nighttime (20:00-7:00), which is essential for investigating nighttime urban climate conditions, especially the urban heat island effect. Moreover, a correlation existed between the nighttime air temperature changes and urban morphology represented by the local climate zones. Air temperatures tended to fall more slowly in the core of metropolitan areas than in the urban fringe. Using ML, this study reliably improves the spatial refinement of hourly air temperature mapping and reveals the spatially explicit air temperature patterns in and around cities at different times in a day during the warm seasons. Moreover, it provides a novel valuable and reliable dataset for air-temperature-related implementation and studies.
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Affiliation(s)
- Guangzhao Chen
- Institute of Future Cities (IOFC), The Chinese University of Hong Kong, Hong Kong, China; Division of Landscape Architecture, Department of Architecture, Faculty of Architecture, The University of Hong Kong, Hong Kong, China
| | - Yuan Shi
- Department of Geography & Planning, University of Liverpool, Liverpool, UK
| | | | - Chao Ren
- Division of Landscape Architecture, Department of Architecture, Faculty of Architecture, The University of Hong Kong, Hong Kong, China.
| | - Edward Ng
- School of Architecture, The Chinese University of Hong Kong, Hong Kong, China
| | - Xiaoyi Fang
- Chinese Academy of Meteorological Sciences, China
| | - Zhihua Ren
- National Meteorological Information Center, China
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Li M, Yang Q, Yuan Q, Zhu L. Estimation of high spatial resolution ground-level ozone concentrations based on Landsat 8 TIR bands with deep forest model. Chemosphere 2022; 301:134817. [PMID: 35523298 DOI: 10.1016/j.chemosphere.2022.134817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2021] [Revised: 04/04/2022] [Accepted: 04/29/2022] [Indexed: 06/14/2023]
Abstract
In recent years, China has been facing severe ozone (O3) pollution, which poses a remarkable threat to human health. Most estimation methods only provide ozone products at a relatively coarse resolution, such as 5 km, but high-resolution ozone data are essential for ozone pollution prevention and control. To this end, we proposed a new framework for estimating ozone concentrations at 300 m resolution in China based on Landsat 8 infrared (IR) bands and meteorological data using a deep forest (DF) model. DF combines the excellent performance of tree integration with the expressive power of hierarchical distributed representations of neural networks. The accuracy and mapping results of DF are considerably better than some widely used machine learning methods (generalized regression neural regression network and random forest). The sample-based cross-validation (CV), station-based CV, time-based CV, and extrapolation validation show that the estimations of DF are in high agreement with the station observations with determination coefficient values of 0.938, 0.926, 0.687, and 0.660, respectively. The proposed method was used to analyze the spatial and temporal ozone variations at fine scales in three typical Chinese cities (Beijing, Wuhan and Guangzhou), where the mean ozone concentrations during the polluted season are consistent with the land use and urban heat island distribution. The rationality of ozone estimates was verified, and the advantages of high-resolution mapping was demonstrated by comparing the monitoring data from municipal controlling stations in Beijing, 10 km ozone products, and satellite images. Our product can represent spatial details and locate local pollution sources, such as temples. The proposed method has important implications for the fine-scale monitoring of ozone pollution.
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Affiliation(s)
- Muyu Li
- School of Geodesy and Geomatics, Wuhan University, Wuhan, Hubei, 430079, China.
| | - Qianqian Yang
- School of Geodesy and Geomatics, Wuhan University, Wuhan, Hubei, 430079, China.
| | - Qiangqiang Yuan
- School of Geodesy and Geomatics, Wuhan University, Wuhan, Hubei, 430079, China; The Key Laboratory of Geospace Environment and Geodesy, Ministry of Education, Wuhan University, Wuhan, Hubei, 430079, China.
| | - Liye Zhu
- School of Atmospheric Sciences and Key Laboratory of Tropical Atmosphere-Ocean System, Sun Yat-sen University, Ministry of Education and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, Guangdong, 519082, China.
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Wang Y, Hu D, Yu C, Di Y, Wang S, Liu M. Appraising regional anthropogenic heat flux using high spatial resolution NTL and POI data: A case study in the Beijing-Tianjin-Hebei region, China. Environ Pollut 2022; 292:118359. [PMID: 34648842 DOI: 10.1016/j.envpol.2021.118359] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 10/08/2021] [Accepted: 10/10/2021] [Indexed: 06/13/2023]
Abstract
Rapid urbanization and the aggregation of human activities in cities have resulted in large amounts of anthropogenic heat (AH) emission, which affects urban climate. Quantifying and assessing the AH emission values accurately and analyzing their spatial distribution characteristics is important to understand the energy exchange processes of urban areas. In this study, the high spatial resolution anthropogenic heat flux (AHF) quantification and spatial distribution analysis were conducted using multi-source data in the Beijing-Tianjin-Hebei region (BTH region) of China. First, the AH emission in district and city level were estimated using inventory method based on energy consumption and socio-economic statistical data; Then, AHF spatial quantification models were constructed based on high spatial resolution nighttime light (NTL) data and Point of interests (POI) data, and 130 m × 130 m gridded AHF quantification result in BTH region was realized; Finally, the potential numerical and spatial distribution patterns of AHF were analyzed using various indicators including contribution rate and aggregation index. The results show that: (1) The parameterized index constructed based on NTL and POI data shows a strong correlation with AHF, with R2 ranging from 0.79 to 0.94 and a mean absolute error (MAE) value of 0.72 w·m-2, which can be applied to the quantification of gridded AHF values with high resolution. The highest total AHF in the study area is 214 w·m-2, and the average value is 2.24 w·m-2. (2) Considering the sources of AHF, industrial emission sources in BTH region contribute the most to the total AHF, but commercial building emission sources in Beijing have a higher contribution, which can reach 33.8%. (3) Different types of AHF have different spatial aggregation levels. Commercial building emission and human metabolic emission have the highest aggregation level, and transportation emission has the lowest aggregation level.
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Affiliation(s)
- Yichen Wang
- College of Resource Environment and Tourism, Capital Normal University, Beijing, 100048, China; Key Laboratory of 3D Information Acquisition and Application, Ministry of Education, Beijing, 100048, China
| | - Deyong Hu
- College of Resource Environment and Tourism, Capital Normal University, Beijing, 100048, China; Key Laboratory of 3D Information Acquisition and Application, Ministry of Education, Beijing, 100048, China.
| | - Chen Yu
- College of Resource Environment and Tourism, Capital Normal University, Beijing, 100048, China; Key Laboratory of 3D Information Acquisition and Application, Ministry of Education, Beijing, 100048, China
| | - Yufei Di
- College of Resource Environment and Tourism, Capital Normal University, Beijing, 100048, China; Key Laboratory of 3D Information Acquisition and Application, Ministry of Education, Beijing, 100048, China
| | - Shasha Wang
- Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology, International Institute for Earth System Science, Nanjing University, Nanjing, Jiangsu, 210023, China
| | - Manqing Liu
- State Key Laboratory of Remote Sensing Science, Faculty of Geographical Science, Beijing Normal University, Beijing, 100875, China
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Chen JE, Glover GH, Fultz NE, Rosen BR, Polimeni JR, Lewis LD. Investigating mechanisms of fast BOLD responses: The effects of stimulus intensity and of spatial heterogeneity of hemodynamics. Neuroimage 2021; 245:118658. [PMID: 34656783 DOI: 10.1016/j.neuroimage.2021.118658] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 09/18/2021] [Accepted: 10/12/2021] [Indexed: 12/17/2022] Open
Abstract
Recent studies have demonstrated that fast fMRI can track neural activity well above the temporal limit predicted by the canonical hemodynamic response model. While these findings are promising, the biophysical mechanisms underlying these fast fMRI phenomena remain underexplored. In this study, we discuss two aspects of the hemodynamic response, complementary to several existing hypotheses, that can accommodate faster fMRI dynamics beyond those predicted by the canonical model. First, we demonstrate, using both visual and somatosensory paradigms, that the timing and shape of hemodynamic response functions (HRFs) vary across graded levels of stimulus intensity-with lower-intensity stimulation eliciting faster and narrower HRFs. Second, we show that as the spatial resolution of fMRI increases, voxel-wise HRFs begin to deviate from the canonical model, with a considerable portion of voxels exhibiting faster temporal dynamics than predicted by the canonical HRF. Collectively, both stimulus/task intensity and image resolution can affect the sensitivity of fMRI to fast brain activity, which may partly explain recent observations of fast fMRI signals. It is further noteworthy that, while the present investigations focus on fast neural responses, our findings suggest that a revised hemodynamic model may benefit the many fMRI studies using paradigms with wide ranges of contrast levels (e.g., resting or naturalistic conditions) or with modern, high-resolution MR acquisitions.
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Shi S, Xu AG, Rui YY, Zhang X, Romanski LM, Gothard KM, Roe AW. Infrared neural stimulation with 7T fMRI: A rapid in vivo method for mapping cortical connections of primate amygdala. Neuroimage 2021; 231:117818. [PMID: 33548458 DOI: 10.1016/j.neuroimage.2021.117818] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 12/18/2020] [Accepted: 01/25/2021] [Indexed: 11/23/2022] Open
Abstract
We have previously shown that INS-fMRI is a rapid method for mapping mesoscale brain networks in the macaque monkey brain. Focal stimulation of single cortical sites led to the activation of connected cortical locations, resulting in a global connectivity map. Here, we have extended this method for mapping brainwide networks following stimulation of single subcortical sites. As a testbed, we focused on the basal nucleus of the amygdala in the macaque monkey. We describe methods to target basal nucleus locations with submillimeter precision, pulse train stimulation methods, and statistical tests for assessing non-random nature of activations. Using these methods, we report that stimulation of precisely targeted loci in the basal nucleus produced sparse and specific activations in the brain. Activations were observed in the insular and sensory association cortices as well as activations in the cingulate cortex, consistent with known anatomical connections. What is new here is that the activations were focal and, in some cases, exhibited shifting topography with millimeter shifts in stimulation site. The precision of the method enables networks mapped from different nearby sites in the basal nucleus to be distinguished. While further investigation is needed to improve the sensitivity of this method, our analyses do support the reproducibility and non-random nature of some of the activations. We suggest that INS-fMRI is a promising method for mapping large-scale cortical and subcortical networks at high spatial resolution.
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Uludag K, Havlicek M. Determining laminar neuronal activity from BOLD fMRI using a generative model. Prog Neurobiol 2021; 207:102055. [PMID: 33930519 DOI: 10.1016/j.pneurobio.2021.102055] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 03/12/2021] [Accepted: 04/20/2021] [Indexed: 11/17/2022]
Abstract
Laminar fMRI using the BOLD contrast enables the non-invasive investigation of mesoscopic functional circuits in the human brain. However, the laminar neuronal activity is spatiotemporally biased in the observed cortical depth profiles of the BOLD signal. In this study, we propose a generative fMRI signal model, comprehensively covering the relationship between cortical depth-dependent changes in excitatory and inhibitory neuronal activity with the sampling of the BOLD signal with finite voxels. The generative model allowed us to investigate pertinent questions regarding the accuracy of the laminar BOLD signal relative to the neuronal activity, and we found that: a) condition differences in laminar BOLD signals may be more reflective of neuronal activity than single condition BOLD signal depth profiles; b) angular dependence of the BOLD signal induces significant signal variability, which can mask underlying activity profiles; c) even if only three neuronal depths are of interest, more BOLD signal depths should be considered in the analysis. In addition, we recommend that the laminar BOLD data should be displayed using the centroid method to appreciate its spatial distribution in the original resolution. Finally, we showed that Bayesian model inversion of the generative model can improve sensitivity and specificity of assessing depth-dependent neuronal changes both for steady-state and dynamically.
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Affiliation(s)
- Kamil Uludag
- Techna Institute & Koerner Scientist in MR Imaging, University Health Network, Toronto, Canada; Center for Neuroscience Imaging Research, Institute for Basic Science & Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Republic of Korea.
| | - Martin Havlicek
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands
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Kim S, Jo Y, Kook G, Pasquinelli C, Kim H, Kim K, Hoe HS, Choe Y, Rhim H, Thielscher A, Kim J, Lee HJ. Transcranial focused ultrasound stimulation with high spatial resolution. Brain Stimul 2021; 14:290-300. [PMID: 33450428 DOI: 10.1016/j.brs.2021.01.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 11/30/2020] [Accepted: 01/06/2021] [Indexed: 10/22/2022] Open
Abstract
BACKGROUND Low-intensity transcranial focused ultrasound stimulation is a promising candidate for noninvasive brain stimulation and accurate targeting of brain circuits because of its focusing capability and long penetration depth. However, achieving a sufficiently high spatial resolution to target small animal sub-regions is still challenging, especially in the axial direction. OBJECTIVE To achieve high axial resolution, we designed a dual-crossed transducer system that achieved high spatial resolution in the axial direction without complex microfabrication, beamforming circuitry, and signal processing. METHODS High axial resolution was achieved by crossing two ultrasound beams of commercially available piezoelectric curved transducers at the focal length of each transducer. After implementation of the fixture for the dual-crossed transducer system, three sets of in vivo animal experiments were conducted to demonstrate high target specificity of ultrasound neuromodulation using the dual-crossed transducer system (n = 38). RESULTS The full-width at half maximum (FWHM) focal volume of our dual-crossed transducer system was under 0.52 μm3. We report a focal diameter in both lateral and axial directions of 1 mm. To demonstrate successful in vivo brain stimulation of wild-type mice, we observed the movement of the forepaws. In addition, we targeted the habenula and verified the high spatial specificity of our dual-crossed transducer system. CONCLUSIONS Our results demonstrate the ability of the dual-crossed transducer system to target highly specific regions of mice brains using ultrasound stimulation. The proposed system is a valuable tool to study the complex neurological circuitry of the brain noninvasively.
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Affiliation(s)
- Seongyeon Kim
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Yehhyun Jo
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Geon Kook
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Cristina Pasquinelli
- Danish Research Centre for Magnetic Resonance (DRCMR), Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Denmark; Center for Magnetic Resonance, Department of Health Technology, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Hyunggug Kim
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Kipom Kim
- Korea Brain Research Institute (KBRI), Daegu, 41068, Republic of Korea
| | - Hyang-Sook Hoe
- Korea Brain Research Institute (KBRI), Daegu, 41068, Republic of Korea
| | - Youngshik Choe
- Korea Brain Research Institute (KBRI), Daegu, 41068, Republic of Korea
| | - Hyewhon Rhim
- Center for Neuroscience, Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea
| | - Axel Thielscher
- Danish Research Centre for Magnetic Resonance (DRCMR), Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Denmark; Center for Magnetic Resonance, Department of Health Technology, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Jeongyeon Kim
- Korea Brain Research Institute (KBRI), Daegu, 41068, Republic of Korea.
| | - Hyunjoo Jenny Lee
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea; KAIST Institute for Health Science and Technology (KIHST), Daejeon, 34141, Republic of Korea; KAIST Institute for NanoCentury (KINC), Daejeon, 34141, Republic of Korea.
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Boillat Y, Bazin PL, van der Zwaag W. Whole-body somatotopic maps in the cerebellum revealed with 7T fMRI. Neuroimage 2020; 211:116624. [PMID: 32058002 DOI: 10.1016/j.neuroimage.2020.116624] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 12/20/2019] [Accepted: 02/06/2020] [Indexed: 12/17/2022] Open
Abstract
The cerebellum is known to contain a double somatotopic body representation. While the anterior lobe body map has shown a robust somatotopic organization in previous fMRI studies, the representations in the posterior lobe have been more difficult to observe and are less precisely characterized. In this study, participants went through a simple motor task asking them to move either the eyes (left-right guided saccades), tongue (left-right movement), thumbs, little fingers or toes (flexion). Using high spatial resolution fMRI data acquired at ultra-high field (7T), with special care taken to obtain sufficient B1 over the entire cerebellum and a cerebellar surface reconstruction facilitating visual inspection of the results, we were able to precisely map the somatotopic representations of these five distal body parts on both subject- and group-specific cerebellar surfaces. The anterior lobe (including lobule VI) showed a consistent and robust somatotopic gradient. Although less robust, the presence of such a gradient in the posterior lobe, from Crus II to lobule VIIIb, was also observed. Additionally, the eyes were also strongly represented in Crus I and the oculomotor vermis. Overall, crosstalk between the different body part representations was negligible. Taken together, these results show that multiple representations of distal body parts are present in the cerebellum, across many lobules, and they are organized in an orderly manner.
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Su S, Lu N, Jia L, Long X, Jiang C, Zhang H, Li Y, Sun K, Xue R, Dharmakumar R, Zhang L, Liu X, Xie G. High spatial resolution BOLD fMRI using simultaneous multislice excitation with echo-shifting gradient echo at 7 Tesla. Magn Reson Imaging 2018; 66:86-92. [PMID: 30172939 DOI: 10.1016/j.mri.2018.08.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 08/08/2018] [Accepted: 08/27/2018] [Indexed: 11/30/2022]
Abstract
We introduce an accelerated gradient echo (GRE) sequence combining simultaneous multislice excitation (SMS) with echo-shifting technique for high spatial resolution blood oxygen level dependent (BOLD) functional MRI (fMRI). The simulation was conducted to optimize scan parameters. To validate the feasibility of the proposed technique, the visual and motor task experiments were performed at 7.0 Tesla (T). The single-shot EPI sequence was also applied in comparison with the proposed technique. The simulation results showed that an optimized flip angle of 9° provided maximal BOLD contrast for our scanning scheme, allowing low power deposition and SMS acceleration factor of 5. Additionally, parallel acquisition imaging with acceleration factor of 2 was utilized, which allowed a total acceleration factor of 10 in volunteer study. The experiment results showed that geometric distortion-free BOLD images with voxel size of 1.0 × 1.0 × 2.5 mm3 were obtained. Significant brain activation was identified in both visual and motor task experiments, which were in accordance with previous investigations. The proposed technique has potential for high spatial resolution fMRI at ultra-high field because of its sufficient BOLD sensitivity as well as improved acquisition speed over conventional GRE-based techniques.
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Affiliation(s)
- Shi Su
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Na Lu
- Department of Biomedical Engineering, School of Basic Sciences, Guangzhou Medical University, Guangzhou, China
| | - Lin Jia
- The Second Affiliated Hospital of Xinjiang Medical University, Urumqi, China
| | - Xiaojing Long
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Chunxiang Jiang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Hang Zhang
- Institutes of Psychological Sciences, Hangzhou Normal University, Hangzhou, China
| | - Ye Li
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Kaibao Sun
- State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Rong Xue
- State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | | | - Lijuan Zhang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Xin Liu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Guoxi Xie
- Department of Biomedical Engineering, School of Basic Sciences, Guangzhou Medical University, Guangzhou, China; The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan, China.
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Fingerhut S, Sperling M, Holling M, Niederstadt T, Allkemper T, Radbruch A, Heindel W, Paulus W, Jeibmann A, Karst U. Gadolinium-based contrast agents induce gadolinium deposits in cerebral vessel walls, while the neuropil is not affected: an autopsy study. Acta Neuropathol 2018; 136:127-38. [PMID: 29748901 DOI: 10.1007/s00401-018-1857-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 04/23/2018] [Accepted: 04/29/2018] [Indexed: 02/02/2023]
Abstract
Recent studies showed gadolinium depositions following serial administrations of gadolinium-based contrast agents (GBCAs) for magnetic resonance imaging examinations in various parts of the brain with the dentate nucleus (DN) being most affected. Even though no clinical correlates of the deposits are known yet, an intensive debate developed if this might be harmful. The aim of the current study was to specify the gadolinium distribution in brain tissue of patients who received serial injections of GBCAs in the low-µm range and to explore any potential pathological tissue changes caused by gadolinium deposits. Thirteen autopsy cases-eight receiving GBCA administrations, five serving as controls-were identified and analyzed. For all patients, total gadolinium quantification after acidic digestion by means of inductively coupled plasma-mass spectrometry (ICP-MS) was performed. Six cases were utilized for the spatially resolved quantification of gadolinium within the cerebellum and the basal ganglia by means of high-resolution laser ablation (LA)-ICP-MS. Histopathological and immunohistochemical examinations were performed to determine tissue reactions. LA-ICP-MS revealed gadolinium depositions in the walls of small blood vessels of the DN in all GBCA exposed patients, while no gadolinium was found in the control group. Additionally, the detection of phosphorus and metals like copper, zinc and iron provides evidence that transmetalation reactions might have occurred. No significant pathological changes of the brain tissue in the vicinity of the DN with respect to micro-/astrogliosis and neuronal loss were found in any of the patients. This notably holds true even for a patient who died from nephrogenic systemic fibrosis exhibiting extremely high gadolinium concentrations within the DN. The findings show that gadolinium depositions in the brain are restricted to blood vessel walls, while the neuropil is spared and apparent cellular reactions are absent.
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Bizino MB, Tao Q, Amersfoort J, Siebelink HMJ, van den Bogaard PJ, van der Geest RJ, Lamb HJ. High spatial resolution free-breathing 3D late gadolinium enhancement cardiac magnetic resonance imaging in ischaemic and non-ischaemic cardiomyopathy: quantitative assessment of scar mass and image quality. Eur Radiol 2018; 28:4027-4035. [PMID: 29626239 PMCID: PMC6096581 DOI: 10.1007/s00330-018-5361-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 01/13/2018] [Accepted: 01/30/2018] [Indexed: 11/28/2022]
Abstract
PURPOSE To compare breath-hold (BH) with navigated free-breathing (FB) 3D late gadolinium enhancement cardiac MRI (LGE-CMR) MATERIALS AND METHODS: Fifty-one patients were retrospectively included (34 ischaemic cardiomyopathy, 14 non-ischaemic cardiomyopathy, three discarded). BH and FB 3D phase sensitive inversion recovery sequences were performed at 3T. FB datasets were reformatted into normal resolution (FB-NR, 1.46x1.46x10mm) and high resolution (FB-HR, isotropic 0.91-mm voxels). Scar mass, scar edge sharpness (SES), SNR and CNR were compared using paired-samples t-test, Pearson correlation and Bland-Altman analysis. RESULTS Scar mass was similar in BH and FB-NR (mean ± SD: 15.5±18.0 g vs. 15.5±16.9 g, p=0.997), with good correlation (r=0.953), and no bias (mean difference ± SD: 0.00±5.47 g). FB-NR significantly overestimated scar mass compared with FB-HR (15.5±16.9 g vs 14.4±15.6 g; p=0.007). FB-NR and FB-HR correlated well (r=0.988), but Bland-Altman demonstrated systematic bias (1.15±2.84 g). SES was similar in BH and FB-NR (p=0.947), but significantly higher in FB-HR than FB-NR (p<0.01). SNR and CNR were lower in BH than FB-NR (p<0.01), and lower in FB-HR than FB-NR (p<0.01). CONCLUSION Navigated free-breathing 3D LGE-CMR allows reliable scar mass quantification comparable to breath-hold. During free-breathing, spatial resolution can be increased resulting in improved sharpness and reduced scar mass. KEY POINTS • Navigated free-breathing 3D late gadolinium enhancement is reliable for myocardial scar quantification. • High-resolution 3D late gadolinium enhancement increases scar sharpness • Ischaemic and non-ischaemic cardiomyopathy patients can be imaged using free-breathing LGE CMR.
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Affiliation(s)
- Maurice B Bizino
- Department of Radiology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands.
| | - Qian Tao
- Department of Radiology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Jacob Amersfoort
- Department of Radiology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Hans-Marc J Siebelink
- Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Pieter J van den Bogaard
- Department of Radiology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Rob J van der Geest
- Department of Radiology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
| | - Hildo J Lamb
- Department of Radiology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands
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Choi W, Ranasinghe D, DeShazo JR, Kim JJ, Paulson SE. Where to locate transit stops: Cross-intersection profiles of ultrafine particles and implications for pedestrian exposure. Environ Pollut 2018; 233:235-245. [PMID: 29096296 DOI: 10.1016/j.envpol.2017.10.055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 10/11/2017] [Accepted: 10/13/2017] [Indexed: 06/07/2023]
Abstract
Epidemiological studies have shown that exposure to traffic-related pollutants increases incidence of adverse health outcomes. Transit users in cities across the globe commonly spend 15-45 min or more waiting at transit stops each day, often at locations with high levels of pollution from traffic. Here, we investigate the characteristics of concentration profiles of ultrafine particles (UFP) with 5 m spatial resolution across intersections, to determine the best place to site transit stops to minimize exposures. Cross-intersection UFP profiles were derived from 1744 profiles covering 90 m before and after each intersection center with a mobile monitoring platform. Measurements were made at 10 signalized intersections located at six urban sites, each with a distinct built environment, during both mornings and afternoons. Measurements were made within 1.5 m of the sidewalk and approximately at breathing height (1.5 m above ground level) to approximate sidewalk exposures. UFP profiles were strongly influenced by high emissions from vehicle stops and accelerations, and peaked within 30 m of intersection centers; from there concentrations decreased sharply with distance. Peak concentrations averaged about 90% higher than the minima along the block. They were accompanied by more frequent and larger transient concentration spikes, increasing the chance of people near the intersection being exposed to both short-term extremely high concentration spikes and higher average concentrations. The decays are somewhat larger before the intersection than after the intersection, however as siting transit stops after intersections is preferred for smooth traffic flow, we focus on after the intersection. Simple time-duration exposure calculations combined with breathing rates suggest moving a bus stop from 20 to 40-50 m after the intersection can reduce transit-users' exposure levels to total UFP substantially, in proportion to the reciprocal of the magnitude of elevation at the intersection.
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Affiliation(s)
- Wonsik Choi
- University of California, Los Angeles, Department of Atmospheric and Oceanic Sciences, Los Angeles, CA, USA; Pukyong National University, Department of Environmental Atmospheric Science, Busan, South Korea
| | - Dilhara Ranasinghe
- University of California, Los Angeles, Department of Atmospheric and Oceanic Sciences, Los Angeles, CA, USA
| | - J R DeShazo
- University of California, Los Angeles, Luskin Center for Innovation, Luskin School of Public Affairs, Los Angeles, CA, USA
| | - Jae-Jin Kim
- Pukyong National University, Department of Environmental Atmospheric Science, Busan, South Korea
| | - Suzanne E Paulson
- University of California, Los Angeles, Department of Atmospheric and Oceanic Sciences, Los Angeles, CA, USA.
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Abstract
Quantitative myelin water imaging (MWI) from signal T2* decay acquired with multiple Gradient-Recalled Echo (mGRE) sequence has been widely used since its first report. A recent study showed that with low resolution data (2mm isotropic voxels), direct application of complex fitting to a three-pool WM model with frequency shift terms could produce more stable parameter estimation for myelin water fraction mapping. MWI maps of higher spatial resolution resulting in more detailed tissue structures and reduced partial volume effects around white matter/gray matter (WM/GM) interface, however, is more desirable. Furthermore, as signal-to-noise ratio (SNR) of original images decreases due to reduced voxel size, the direct complex fitting procedure of myelin water imaging becomes more prone to systematic errors which severely compromised stability and reliability of the result. Instead of using the original part of T2* decay, this work presents a new method based on the WM-induced phase from tissue susceptibility calculated with the same mGRE dataset, in a three-pool WM model (water of myelin, axonal and extracellular water), to improve high resolution MWI. Compared with direct complex fitting for the higher spatial resolution case, the proposed method is shown to provide a more stable and accurate estimation of MWI parameters, and finer details near WM/GM boundaries with greatly reduced partial volume effects.
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Affiliation(s)
- Zhe Wu
- Center for Brain Imaging Science and Technology, Key Laboratory for Biomedical Engineering of Ministry of Education, College of Biomedical Engineering and Instrumental Science, Zhejiang University, Hangzhou, Zhejiang, China
| | - Hongjian He
- Center for Brain Imaging Science and Technology, Key Laboratory for Biomedical Engineering of Ministry of Education, College of Biomedical Engineering and Instrumental Science, Zhejiang University, Hangzhou, Zhejiang, China.
| | - Yi Sun
- MR Collaboration NE Asia, Siemens Healthcare, Shanghai, China
| | - Yiping Du
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Jianhui Zhong
- Center for Brain Imaging Science and Technology, Key Laboratory for Biomedical Engineering of Ministry of Education, College of Biomedical Engineering and Instrumental Science, Zhejiang University, Hangzhou, Zhejiang, China; Center for Innovative and Collaborative Detection and Treatment of Infectious Diseases, Zhejiang University, Hangzhou, Zhejiang, China; Department of Imaging Sciences, University of Rochester, NY, USA.
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17
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De Martino F, Yacoub E, Kemper V, Moerel M, Uludağ K, De Weerd P, Ugurbil K, Goebel R, Formisano E. The impact of ultra-high field MRI on cognitive and computational neuroimaging. Neuroimage 2017; 168:366-382. [PMID: 28396293 DOI: 10.1016/j.neuroimage.2017.03.060] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 03/20/2017] [Accepted: 03/29/2017] [Indexed: 01/14/2023] Open
Abstract
The ability to measure functional brain responses non-invasively with ultra high field MRI (7 T and above) represents a unique opportunity in advancing our understanding of the human brain. Compared to lower fields (3 T and below), ultra high field MRI has an increased sensitivity, which can be used to acquire functional images with greater spatial resolution, and greater specificity of the blood oxygen level dependent (BOLD) signal to the underlying neuronal responses. Together, increased resolution and specificity enable investigating brain functions at a submillimeter scale, which so far could only be done with invasive techniques. At this mesoscopic spatial scale, perception, cognition and behavior can be probed at the level of fundamental units of neural computations, such as cortical columns, cortical layers, and subcortical nuclei. This represents a unique and distinctive advantage that differentiates ultra high from lower field imaging and that can foster a tighter link between fMRI and computational modeling of neural networks. So far, functional brain mapping at submillimeter scale has focused on the processing of sensory information and on well-known systems for which extensive information is available from invasive recordings in animals. It remains an open challenge to extend this methodology to uniquely human functions and, more generally, to systems for which animal models may be problematic. To succeed, the possibility to acquire high-resolution functional data with large spatial coverage, the availability of computational models of neural processing as well as accurate biophysical modeling of neurovascular coupling at mesoscopic scale all appear necessary.
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Affiliation(s)
- Federico De Martino
- Department of Cognitive Neurosciences, Faculty of Psychology and Neuroscience, Maastricht University, Oxfordlaan 55, 6229 ER Maastricht, The Netherlands; Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, 2021 sixth street SE, 55455 Minneapolis, MN, USA.
| | - Essa Yacoub
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, 2021 sixth street SE, 55455 Minneapolis, MN, USA
| | - Valentin Kemper
- Department of Cognitive Neurosciences, Faculty of Psychology and Neuroscience, Maastricht University, Oxfordlaan 55, 6229 ER Maastricht, The Netherlands
| | - Michelle Moerel
- Department of Cognitive Neurosciences, Faculty of Psychology and Neuroscience, Maastricht University, Oxfordlaan 55, 6229 ER Maastricht, The Netherlands; Maastricht Center for System Biology, Maastricht University, Universiteitssingel 60, 6229 ER Maastricht, The Netherlands
| | - Kâmil Uludağ
- Department of Cognitive Neurosciences, Faculty of Psychology and Neuroscience, Maastricht University, Oxfordlaan 55, 6229 ER Maastricht, The Netherlands
| | - Peter De Weerd
- Department of Cognitive Neurosciences, Faculty of Psychology and Neuroscience, Maastricht University, Oxfordlaan 55, 6229 ER Maastricht, The Netherlands
| | - Kamil Ugurbil
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, 2021 sixth street SE, 55455 Minneapolis, MN, USA
| | - Rainer Goebel
- Department of Cognitive Neurosciences, Faculty of Psychology and Neuroscience, Maastricht University, Oxfordlaan 55, 6229 ER Maastricht, The Netherlands
| | - Elia Formisano
- Department of Cognitive Neurosciences, Faculty of Psychology and Neuroscience, Maastricht University, Oxfordlaan 55, 6229 ER Maastricht, The Netherlands; Maastricht Center for System Biology, Maastricht University, Universiteitssingel 60, 6229 ER Maastricht, The Netherlands
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Dueñas ME, Carlucci L, Lee YJ. Matrix Recrystallization for MALDI-MS Imaging of Maize Lipids at High-Spatial Resolution. J Am Soc Mass Spectrom 2016; 27:1575-8. [PMID: 27349253 DOI: 10.1007/s13361-016-1422-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 05/13/2016] [Accepted: 05/14/2016] [Indexed: 05/13/2023]
Abstract
Matrix recrystallization is optimized and applied to improve lipid ion signals in maize embryos and leaves. A systematic study was performed varying solvent and incubation time. During this study, unexpected side reactions were found when methanol was used as a recrystallization solvent, resulting in the formation of a methyl ester of phosphatidic acid. Using an optimum recrystallization condition with isopropanol, there is no apparent delocalization demonstrated with a transmission electron microscopy (TEM) pattern and maize leaf images obtained at 10 μm spatial resolution. Graphical Abstract ᅟ.
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Affiliation(s)
- Maria Emilia Dueñas
- Ames Laboratory, US Department of Energy, Ames, IA, 50011, USA
- Department of Chemistry, Iowa State University of Science and Technology, Ames, IA, 50011, USA
| | - Laura Carlucci
- Ames Laboratory, US Department of Energy, Ames, IA, 50011, USA
| | - Young Jin Lee
- Ames Laboratory, US Department of Energy, Ames, IA, 50011, USA.
- Department of Chemistry, Iowa State University of Science and Technology, Ames, IA, 50011, USA.
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19
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Bianciardi M, Toschi N, Eichner C, Polimeni JR, Setsompop K, Brown EN, Hämäläinen MS, Rosen BR, Wald LL. In vivo functional connectome of human brainstem nuclei of the ascending arousal, autonomic, and motor systems by high spatial resolution 7-Tesla fMRI. MAGMA 2016; 29:451-62. [PMID: 27126248 DOI: 10.1007/s10334-016-0546-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 02/18/2016] [Accepted: 03/07/2016] [Indexed: 01/07/2023]
Abstract
OBJECTIVE Our aim was to map the in vivo human functional connectivity of several brainstem nuclei with the rest of the brain by using seed-based correlation of ultra-high magnetic field functional magnetic resonance imaging (fMRI) data. MATERIALS AND METHODS We used the recently developed template of 11 brainstem nuclei derived from multi-contrast structural MRI at 7 Tesla as seed regions to determine their connectivity to the rest of the brain. To achieve this, we used the increased contrast-to-noise ratio of 7-Tesla fMRI compared with 3 Tesla and time-efficient simultaneous multi-slice imaging to cover the brain with high spatial resolution (1.1-mm isotropic nominal resolution) while maintaining a short repetition time (2.5 s). RESULTS The delineated Pearson's correlation-based functional connectivity diagrams (connectomes) of 11 brainstem nuclei of the ascending arousal, motor, and autonomic systems from 12 controls are presented and discussed in the context of existing histology and animal work. CONCLUSION Considering that the investigated brainstem nuclei play a crucial role in several vital functions, the delineated preliminary connectomes might prove useful for future in vivo research and clinical studies of human brainstem function and pathology, including disorders of consciousness, sleep disorders, autonomic disorders, Parkinson's disease, and other motor disorders.
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Affiliation(s)
- Marta Bianciardi
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Building 149, Room 2301, 13th Street, Charlestown, Boston, MA, 02129, USA.
| | - Nicola Toschi
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Building 149, Room 2301, 13th Street, Charlestown, Boston, MA, 02129, USA.,Medical Physics Section, Department of Biomedicine and Prevention, Faculty of Medicine, University of Rome "Tor Vergata", Via Montpellier 1, 00133, Rome, Italy
| | - Cornelius Eichner
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Building 149, Room 2301, 13th Street, Charlestown, Boston, MA, 02129, USA
| | - Jonathan R Polimeni
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Building 149, Room 2301, 13th Street, Charlestown, Boston, MA, 02129, USA
| | - Kawin Setsompop
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Building 149, Room 2301, 13th Street, Charlestown, Boston, MA, 02129, USA
| | - Emery N Brown
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, 55 Fruit Street, Boston, MA, 02114, USA
| | - Matti S Hämäläinen
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Building 149, Room 2301, 13th Street, Charlestown, Boston, MA, 02129, USA
| | - Bruce R Rosen
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Building 149, Room 2301, 13th Street, Charlestown, Boston, MA, 02129, USA
| | - Lawrence L Wald
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Building 149, Room 2301, 13th Street, Charlestown, Boston, MA, 02129, USA
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20
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Song Y, Conner J, Zhang X, Hayward JP. Monte Carlo simulation of a very high resolution thermal neutron detector composed of glass scintillator microfibers. Appl Radiat Isot 2015; 108:100-107. [PMID: 26708515 DOI: 10.1016/j.apradiso.2015.12.035] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 12/09/2015] [Accepted: 12/10/2015] [Indexed: 11/27/2022]
Abstract
In order to develop a high spatial resolution (micron level) thermal neutron detector, a detector assembly composed of cerium doped lithium glass microfibers, each with a diameter of 1 μm, is proposed, where the neutron absorption location is reconstructed from the observed charged particle products that result from neutron absorption. To suppress the cross talk of the scintillation light, each scintillating fiber is surrounded by air-filled glass capillaries with the same diameter as the fiber. This pattern is repeated to form a bulk microfiber detector. On one end, the surface of the detector is painted with a thin optical reflector to increase the light collection efficiency at the other end. Then the scintillation light emitted by any neutron interaction is transmitted to one end, magnified, and recorded by an intensified CCD camera. A simulation based on the Geant4 toolkit was developed to model this detector. All the relevant physics processes including neutron interaction, scintillation, and optical boundary behaviors are simulated. This simulation was first validated through measurements of neutron response from lithium glass cylinders. With good expected light collection, an algorithm based upon the features inherent to alpha and triton particle tracks is proposed to reconstruct the neutron reaction position in the glass fiber array. Given a 1 μm fiber diameter and 0.1mm detector thickness, the neutron spatial resolution is expected to reach σ∼1 μm with a Gaussian fit in each lateral dimension. The detection efficiency was estimated to be 3.7% for a glass fiber assembly with thickness of 0.1mm. When the detector thickness increases from 0.1mm to 1mm, the position resolution is not expected to vary much, while the detection efficiency is expected to increase by about a factor of ten.
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Affiliation(s)
- Yushou Song
- Key Discipline Laboratory of Nuclear Safety and Simulation Technology, Harbin Engineering University, Harbin 150001, China
| | - Joseph Conner
- Nuclear Engineering Department, University of Tennessee, Knoxville, TN 37996, USA
| | - Xiaodong Zhang
- Nuclear Engineering Department, University of Tennessee, Knoxville, TN 37996, USA
| | - Jason P Hayward
- Nuclear Engineering Department, University of Tennessee, Knoxville, TN 37996, USA.
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Kamali A, Hasan KM, Adapa P, Razmandi A, Keser Z, Lincoln J, Kramer LA. Distinguishing and quantification of the human visual pathways using high-spatial-resolution diffusion tensor tractography. Magn Reson Imaging 2014; 32:796-803. [PMID: 24856625 DOI: 10.1016/j.mri.2014.04.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2013] [Revised: 03/08/2014] [Accepted: 04/03/2014] [Indexed: 11/21/2022]
Abstract
Quantification of the living human visual system using MRI methods has been challenging, but several applications demand a reliable and time-efficient data acquisition protocol. In this study, we demonstrate the utility of high-spatial-resolution diffusion tensor fiber tractography (DTT) in reconstructing and quantifying the human visual pathways. Five healthy males, age range 24-37years, were studied after approval of the institutional review board (IRB) at The University of Texas Health Science Center at Houston. We acquired diffusion tensor imaging (DTI) data with 1-mm slice thickness on a 3.0-Tesla clinical MRI scanner and analyzed the data using DTT with the fiber assignment by continuous tractography (FACT) algorithm. By utilizing the high-spatial-resolution DTI protocol with FACT algorithm, we were able to reconstruct and quantify bilateral optic pathways including the optic chiasm, optic tract, optic radiations free of contamination from neighboring white matter tracts.
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