The Experts below are selected from a list of 27798 Experts worldwide ranked by ideXlab platform
Juha Töyräs - One of the best experts on this subject based on the ideXlab platform.
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author correction artificial neural network analysis of the oxygen Saturation Signal enables accurate diagnostics of sleep apnea
2020Co-Authors: Sami Nikkonen, Isaac O. Afara, Timo Leppänen, Juha TöyräsAbstract:This Article incorrectly states that informed consent was obtained. Consent for research was not sought, because under Finnish law (Law on medical research 2 § (23.4.2004/295)) the need for consent is not required for retrospective chart reviews.
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Artificial neural network analysis of the oxygen Saturation Signal enables accurate diagnostics of sleep apnea
2019Co-Authors: Sami Nikkonen, Isaac O. Afara, Timo Leppänen, Juha TöyräsAbstract:The severity of obstructive sleep apnea (OSA) is classified using apnea-hypopnea index (AHI). Accurate determination of AHI currently requires manual analysis and complicated registration setup making it expensive and labor intensive. Partially for these reasons, OSA is a heavily underdiagnosed disease as only 7% of women and 18% of men suffering from OSA have diagnosis. To resolve these issues, we introduce an artificial neural network (ANN) that estimates AHI and oxygen deSaturation index (ODI) using only the blood oxygen Saturation Signal (SpO2), recorded during ambulatory polygraphy, as an input. Therefore, hypopneas associated only with an arousal were not considered in this study. SpO2 Signals from 1692 patients were used for training and 99 for validation. Two test sets were used consisting of 198 and 1959 patients. In the primary test set, the median absolute errors of ANN estimated AHI and ODI were 0.78 events/hour and 0.68 events/hour respectively. Based on the ANN estimated AHI and ODI, 90.9% and 94.4% of the test patients were classified into the correct OSA severity category. In conclusion, AHI and ODI can be reliably determined using neural network analysis of SpO2 Signal. The developed method may enable a more affordable screening of OSA.
Jinyuan Zhou - One of the best experts on this subject based on the ideXlab platform.
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in vivo three dimensional whole brain pulsed steady state chemical exchange Saturation transfer at 7 t
2012Co-Authors: Craig K Jones, Daniel Polders, Hans Hoogduin, Jinyuan Zhou, Peter R Luijten, Peter C M Van ZijlAbstract:Chemical exchange Saturation transfer (CEST) is a technique to indirectly detect pools of exchangeable protons through the water Signal. To increase its applicability to human studies, it is needed to develop sensitive pulse sequences for rapidly acquiring whole-organ images while adhering to stringent amplifier duty cycle limitations and specific absorption rate restrictions. In addition, the interfering effects of direct water Saturation and conventional magnetization transfer contrast complicate CEST quantification and need to be reduced as much as possible. It is shown that for protons exchanging with rates of less than 50–100 Hz, such as imaged in amide proton transfer experiments, these problems can be addressed by using a three-dimensional steady state pulsed acquisition of limited B1 strength (∼1 μT). Such an approach exploits the fact that the direct water Saturation width, magnetization transfer contrast magnitude, and specific absorption rate increase strongly with B1, while the size of the CEST effect for such protons depends minimally on B1. A short repetition time (65 ms) steady-state sequence consisting of a brief Saturation pulse (25 ms) and a segmented echo-planar imaging train allowed acquisition of a three-dimensional whole-brain volume in approximately 11 s per Saturation frequency, while remaining well within specific absorption rate and duty cycle limits. Magnetization transfer contrast was strongly reduced, but substantial Saturation effects were found at frequencies upfield from water, which still confound the use of magnetization transfer asymmetry analysis. Fortunately, the limited width of the direct water Saturation Signal could be exploited to fit it with a Lorentzian function allowing CEST quantification. Amide proton transfer effects ranged between 1.5% and 2.5% in selected white and grey matter regions. This power and time-efficient 3D pulsed CEST acquisition scheme should aid endogenous CEST quantification at both high and low fields. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.
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in vivo three dimensional whole brain pulsed steady state chemical exchange Saturation transfer at 7 t
2012Co-Authors: Craig K Jones, Daniel Polders, Hans Hoogduin, Jinyuan Zhou, Jun Hua, He ZhuAbstract:Chemical exchange Saturation transfer (CEST) is a technique to indirectly detect pools of exchangeable protons through the water Signal. To increase its applicability to human studies, it is needed to develop sensitive pulse sequences for rapidly acquiring whole-organ images while adhering to stringent amplifier duty cycle limitations and specific absorption rate restrictions. In addition, the interfering effects of direct water Saturation and conventional magnetization transfer contrast complicate CEST quantification and need to be reduced as much as possible. It is shown that for protons exchanging with rates of less than 50-100 Hz, such as imaged in amide proton transfer experiments, these problems can be addressed by using a three-dimensional steady state pulsed acquisition of limited B(1) strength (≈ 1 μT). Such an approach exploits the fact that the direct water Saturation width, magnetization transfer contrast magnitude, and specific absorption rate increase strongly with B(1) , while the size of the CEST effect for such protons depends minimally on B(1) . A short repetition time (65 ms) steady-state sequence consisting of a brief Saturation pulse (25 ms) and a segmented echo-planar imaging train allowed acquisition of a three-dimensional whole-brain volume in approximately 11 s per Saturation frequency, while remaining well within specific absorption rate and duty cycle limits. Magnetization transfer contrast was strongly reduced, but substantial Saturation effects were found at frequencies upfield from water, which still confound the use of magnetization transfer asymmetry analysis. Fortunately, the limited width of the direct water Saturation Signal could be exploited to fit it with a Lorentzian function allowing CEST quantification. Amide proton transfer effects ranged between 1.5% and 2.5% in selected white and grey matter regions. This power and time-efficient 3D pulsed CEST acquisition scheme should aid endogenous CEST quantification at both high and low fields.
Craig K Jones - One of the best experts on this subject based on the ideXlab platform.
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in vivo three dimensional whole brain pulsed steady state chemical exchange Saturation transfer at 7 t
2012Co-Authors: Craig K Jones, Daniel Polders, Hans Hoogduin, Jinyuan Zhou, Peter R Luijten, Peter C M Van ZijlAbstract:Chemical exchange Saturation transfer (CEST) is a technique to indirectly detect pools of exchangeable protons through the water Signal. To increase its applicability to human studies, it is needed to develop sensitive pulse sequences for rapidly acquiring whole-organ images while adhering to stringent amplifier duty cycle limitations and specific absorption rate restrictions. In addition, the interfering effects of direct water Saturation and conventional magnetization transfer contrast complicate CEST quantification and need to be reduced as much as possible. It is shown that for protons exchanging with rates of less than 50–100 Hz, such as imaged in amide proton transfer experiments, these problems can be addressed by using a three-dimensional steady state pulsed acquisition of limited B1 strength (∼1 μT). Such an approach exploits the fact that the direct water Saturation width, magnetization transfer contrast magnitude, and specific absorption rate increase strongly with B1, while the size of the CEST effect for such protons depends minimally on B1. A short repetition time (65 ms) steady-state sequence consisting of a brief Saturation pulse (25 ms) and a segmented echo-planar imaging train allowed acquisition of a three-dimensional whole-brain volume in approximately 11 s per Saturation frequency, while remaining well within specific absorption rate and duty cycle limits. Magnetization transfer contrast was strongly reduced, but substantial Saturation effects were found at frequencies upfield from water, which still confound the use of magnetization transfer asymmetry analysis. Fortunately, the limited width of the direct water Saturation Signal could be exploited to fit it with a Lorentzian function allowing CEST quantification. Amide proton transfer effects ranged between 1.5% and 2.5% in selected white and grey matter regions. This power and time-efficient 3D pulsed CEST acquisition scheme should aid endogenous CEST quantification at both high and low fields. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.
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in vivo three dimensional whole brain pulsed steady state chemical exchange Saturation transfer at 7 t
2012Co-Authors: Craig K Jones, Daniel Polders, Hans Hoogduin, Jinyuan Zhou, Jun Hua, He ZhuAbstract:Chemical exchange Saturation transfer (CEST) is a technique to indirectly detect pools of exchangeable protons through the water Signal. To increase its applicability to human studies, it is needed to develop sensitive pulse sequences for rapidly acquiring whole-organ images while adhering to stringent amplifier duty cycle limitations and specific absorption rate restrictions. In addition, the interfering effects of direct water Saturation and conventional magnetization transfer contrast complicate CEST quantification and need to be reduced as much as possible. It is shown that for protons exchanging with rates of less than 50-100 Hz, such as imaged in amide proton transfer experiments, these problems can be addressed by using a three-dimensional steady state pulsed acquisition of limited B(1) strength (≈ 1 μT). Such an approach exploits the fact that the direct water Saturation width, magnetization transfer contrast magnitude, and specific absorption rate increase strongly with B(1) , while the size of the CEST effect for such protons depends minimally on B(1) . A short repetition time (65 ms) steady-state sequence consisting of a brief Saturation pulse (25 ms) and a segmented echo-planar imaging train allowed acquisition of a three-dimensional whole-brain volume in approximately 11 s per Saturation frequency, while remaining well within specific absorption rate and duty cycle limits. Magnetization transfer contrast was strongly reduced, but substantial Saturation effects were found at frequencies upfield from water, which still confound the use of magnetization transfer asymmetry analysis. Fortunately, the limited width of the direct water Saturation Signal could be exploited to fit it with a Lorentzian function allowing CEST quantification. Amide proton transfer effects ranged between 1.5% and 2.5% in selected white and grey matter regions. This power and time-efficient 3D pulsed CEST acquisition scheme should aid endogenous CEST quantification at both high and low fields.
Kenji Azami - One of the best experts on this subject based on the ideXlab platform.
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224 ke Saturation Signal global shutter cmos image sensor with in pixel pinned storage and lateral overflow integration capacitor
2017Co-Authors: Yorito Sakano, Shin Sakai, Yoshiaki Tashiro, Yuri Kato, Kentaro Akiyama, Katsumi Honda, Mamoru Sato, Masaki Sakakibara, Tadayuki Taura, Kenji AzamiAbstract:The required incorporation of an additional in-pixel retention node for global shutter complementary metal-oxide semiconductor (CMOS) image sensors means that achieving a large Saturation Signal presents a challenge. This paper reports a 3.875-μm pixel single exposure global shutter CMOS image sensor with an in-pixel pinned storage (PST) and a lateral-overflow integration capacitor (LOFIC), which extends the Saturation Signal to 224 ke, thereby enabling the Saturation Signal per unit area to reach 14.9 ke/μm. This pixel can assure a large Saturation Signal by using a LOFIC for accumulation without degrading the image quality under dark and low illuminance conditions owing to the PST.
Peter C M Van Zijl - One of the best experts on this subject based on the ideXlab platform.
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in vivo three dimensional whole brain pulsed steady state chemical exchange Saturation transfer at 7 t
2012Co-Authors: Craig K Jones, Daniel Polders, Hans Hoogduin, Jinyuan Zhou, Peter R Luijten, Peter C M Van ZijlAbstract:Chemical exchange Saturation transfer (CEST) is a technique to indirectly detect pools of exchangeable protons through the water Signal. To increase its applicability to human studies, it is needed to develop sensitive pulse sequences for rapidly acquiring whole-organ images while adhering to stringent amplifier duty cycle limitations and specific absorption rate restrictions. In addition, the interfering effects of direct water Saturation and conventional magnetization transfer contrast complicate CEST quantification and need to be reduced as much as possible. It is shown that for protons exchanging with rates of less than 50–100 Hz, such as imaged in amide proton transfer experiments, these problems can be addressed by using a three-dimensional steady state pulsed acquisition of limited B1 strength (∼1 μT). Such an approach exploits the fact that the direct water Saturation width, magnetization transfer contrast magnitude, and specific absorption rate increase strongly with B1, while the size of the CEST effect for such protons depends minimally on B1. A short repetition time (65 ms) steady-state sequence consisting of a brief Saturation pulse (25 ms) and a segmented echo-planar imaging train allowed acquisition of a three-dimensional whole-brain volume in approximately 11 s per Saturation frequency, while remaining well within specific absorption rate and duty cycle limits. Magnetization transfer contrast was strongly reduced, but substantial Saturation effects were found at frequencies upfield from water, which still confound the use of magnetization transfer asymmetry analysis. Fortunately, the limited width of the direct water Saturation Signal could be exploited to fit it with a Lorentzian function allowing CEST quantification. Amide proton transfer effects ranged between 1.5% and 2.5% in selected white and grey matter regions. This power and time-efficient 3D pulsed CEST acquisition scheme should aid endogenous CEST quantification at both high and low fields. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.
