The Experts below are selected from a list of 342 Experts worldwide ranked by ideXlab platform
Licia Uccelli - One of the best experts on this subject based on the ideXlab platform.
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recent achievements in tc 99m radiopharmaceutical direct production by medical cyclotrons
Drug Development and Industrial Pharmacy, 2017Co-Authors: Alessandra Boschi, Petra Martini, Micol Pasquali, Licia UccelliAbstract:Abstract99mTc is the most commonly used radionuclide in the field of Diagnostic imaging, a noninvasive method intended to diagnose a disease, assess the disease state and monitor the effects of treatments. Annually, the use of 99mTc, covers about 85% of nuclear medicine applications. This isotope releases gamma rays at about the same wavelength as conventional X-ray Diagnostic Equipment, and owing to its short half-life (t½ = 6 h) is ideal for Diagnostic nuclear imaging. A patient can be injected with a small amount of 99mTc and within 24 h almost 94% of the injected radionuclide would have decayed and left the body, limiting the patient’s radiation exposure. 99mTc is usually supplied to hospitals through a 99Mo/99mTc radionuclide generator system where it is produced from the β decay of the parent nuclide 99Mo (t½ = 66 h), which is produced in nuclear reactors via neutron fission. Recently, the interruption of the global supply chain of reactor-produced 99Mo, has forced the scientific community to invest...
Hiroshi Kanai - One of the best experts on this subject based on the ideXlab platform.
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development of an ultrasonic probe to measure both radial arterial pressure and diameter change at the same position for early diagnosis of vascular endothelial function preliminary study
Sensors and Actuators A-physical, 2019Co-Authors: Mototaka Arakawa, Takumi Saito, Shohei Mori, S Ohba, Kazuto Kobayashi, Hiroshi KanaiAbstract:Abstract We have evaluated the viscoelastic properties of arterial walls by measuring the relationship from radial arterial pressure to the change in arterial diameter to evaluate vascular endothelial functions. In our previous study, these parameters were measured at different positions, which caused timing errors. In the present study, a novel probe was developed to measure both radial arterial pressure and the change in arterial diameter at the same position. The central piezoelectric element of the linear array probe was disconnected from the ultrasonic Diagnostic Equipment and used to measure the arterial pressure. To obtain the blood pressure waveform, the output was integrated and calibrated using the systolic and diastolic pressures measured by a conventional sphygmomanometer. The arterial diameter was measured using the other 191 elements of the ultrasonic Diagnostic apparatus via the phased-tracking method. The hysteresis loop, which is the relationship between the change in diameter and instantaneous pressure during a heartbeat, and thus reflects the viscoelasticity of the arterial wall, was measured successfully. The reproducibility for successive two heartbeats was confirmed for two subjects.
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high frame rate echocardiography using diverging transmit beams and parallel receive beamforming
Journal of Medical Ultrasonics, 2014Co-Authors: Hideyuki Hasegawa, Hiroshi KanaiAbstract:Echocardiography is a widely used modality for diagnosis of the heart. It enables observation of the shape of the heart and estimation of global heart function based on B-mode and M-mode imaging. Subsequently, methods for estimating myocardial strain and strain rate have been developed to evaluate regional heart function. Furthermore, it has recently been shown that measurements of transmural transition of myocardial contraction/relaxation and propagation of vibration caused by closure of a heart valve would be useful for evaluation of myocardial function and viscoelasticity. However, such measurements require a frame rate much higher than that achieved by conventional ultrasonic Diagnostic Equipment. In the present study, a method based on parallel receive beamforming was developed to achieve high-frame-rate (over 300 Hz) echocardiography. To increase the frame rate, the number of transmits was reduced to 15 with angular intervals of 6°, and 16 receiving beams were created for each transmission to obtain the same number and density of scan lines as realized by conventional sector scanning. In addition, several transmits were compounded to obtain each scan line to reduce the differences in transmit–receive sensitivities among scan lines. The number of transmits for compounding was determined by considering the width of the transmit beam. For transmission, plane waves and diverging waves were investigated. Diverging waves showed better performance than plane waves because the widths of plane waves did not increase with the range distance from the ultrasonic probe, whereas lateral intervals of scan lines increased with range distance. The spatial resolution of the proposed method was validated using fine nylon wires. Although the widths at half-maxima of the point spread functions obtained by diverging waves were slightly larger than those obtained by conventional beamforming and parallel beamforming with plane waves, point spread functions very similar to those obtained by conventional beamforming could be realized by parallel beamforming with diverging beams and compounding. However, there was an increase in the lateral sidelobe level in the case of parallel beamforming with plane and diverging waves. Furthermore, the heart of a 23-year-old healthy male was measured. Although the contrast of the B-mode image obtained by the proposed method was degraded due to the increased sidelobe level, a frame rate of 316 Hz, much higher than that realized by conventional sector scanning of several tens of Hertz, was realized with a full lateral field of view of 90°.
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increasing bandwidth of ultrasound radio frequency echoes using wiener filter for improvement of accuracy in measurement of intima media thickness
Japanese Journal of Applied Physics, 2013Co-Authors: Sho Kageyama, Hideyuki Hasegawa, Hiroshi KanaiAbstract:It is very important to make early diagnoses of atherosclerosis for the prevention of lifestyle-related diseases. The intima–media thickness (IMT) is used as a Diagnostic index of cerebrovascular diseases and atherosclerosis throughout the body including the coronary artery. In the field of the medical Diagnostics, ultrasonic Equipment using a pulse–echo method is widely used. In conventional ultrasonic Diagnostic Equipment, ultrasonic images are obtained by receiving ultrasonic echoes and converting their amplitudes into brightness. In general, ultrasonic B-mode images are degraded by the narrow-band characteristics of the ultrasonic transducer. In the present study, a method was proposed for shortening the lengths of the received ultrasonic pulses from an object of interest using a Wiener filter. As a result, the lengths of ultrasonic pulses were shortened and the visibility of interfaces of the intima–media complex of the carotid arterial wall was improved by the proposed method, which realizes accurate measurement of the IMT.
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improving accuracy in estimation of artery wall displacement by referring to center frequency of rf echo
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control, 2006Co-Authors: Hideyuki Hasegawa, Hiroshi KanaiAbstract:Noninvasive measurement of mechanical properties, such as elasticity, of the arterial wall, is useful for diagnosis of atherosclerosis. The elasticity of the arterial wall can be estimated by combining measurement of displacement of the arterial wall with that of blood pressure. In general, the displacement of the arterial wall is estimated from the phase shift of radio frequency (RF) echoes between two consecutive frames using a correlation estimator with quadrature demodulated complex signals. Recently, digitized data of broadband RF echoes are available in modern Diagnostic Equipment. The Fourier transform can be used to estimate the phase of the RF echo at each frequency within the RF frequency bandwidth. Therefore, the phase shifts between RF echoes of two consecutive frames can be estimated at multiple frequencies. In this estimation, due to object displacement, the RF echo is time shifted in comparison with that of the previous frame. However, the position of the time window for the Fourier transform is not changed between two consecutive frames. This change in relative position between the RF echo and the time window has a strong influence on the estimation of the artery-wall displacement, resulting in error. To suppress this error, the phase shift should be estimated at the actual RF center frequency. In this paper, this error suppression was investigated through simulation experiments and in vivo experiments on the human carotid artery.
Alessandra Boschi - One of the best experts on this subject based on the ideXlab platform.
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recent achievements in tc 99m radiopharmaceutical direct production by medical cyclotrons
Drug Development and Industrial Pharmacy, 2017Co-Authors: Alessandra Boschi, Petra Martini, Micol Pasquali, Licia UccelliAbstract:Abstract99mTc is the most commonly used radionuclide in the field of Diagnostic imaging, a noninvasive method intended to diagnose a disease, assess the disease state and monitor the effects of treatments. Annually, the use of 99mTc, covers about 85% of nuclear medicine applications. This isotope releases gamma rays at about the same wavelength as conventional X-ray Diagnostic Equipment, and owing to its short half-life (t½ = 6 h) is ideal for Diagnostic nuclear imaging. A patient can be injected with a small amount of 99mTc and within 24 h almost 94% of the injected radionuclide would have decayed and left the body, limiting the patient’s radiation exposure. 99mTc is usually supplied to hospitals through a 99Mo/99mTc radionuclide generator system where it is produced from the β decay of the parent nuclide 99Mo (t½ = 66 h), which is produced in nuclear reactors via neutron fission. Recently, the interruption of the global supply chain of reactor-produced 99Mo, has forced the scientific community to invest...
Andrea B Maier - One of the best experts on this subject based on the ideXlab platform.
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lack of knowledge and availability of Diagnostic Equipment could hinder the diagnosis of sarcopenia and its management
PLOS ONE, 2017Co-Authors: Esmee M Reijnierse, Marian A E De Van Der Schueren, Marijke C Trappenburg, Marjan Doves, Carel G. M. Meskers, Andrea B MaierAbstract:Objectives Sarcopenia is an emerging clinical challenge in an ageing population and is associated with serious negative health outcomes. This study aimed to assess the current state of the art regarding the knowledge about the concept of sarcopenia and practice of the Diagnostic strategy and management of sarcopenia in a cohort of Dutch healthcare professionals (physicians, physiotherapists, dietitians and others) attending a lecture cycle on sarcopenia. Material and methods This longitudinal study included Dutch healthcare professionals (n = 223) who were asked to complete a questionnaire before, directly after and five months after (n = 80) attending a lecture cycle on the pathophysiology of sarcopenia, Diagnostic strategy and management of sarcopenia, i.e. interventions and collaboration. Results Before attendance, 69.7% of healthcare professionals stated to know the concept of sarcopenia, 21.4% indicated to know how to diagnose sarcopenia and 82.6% had treated patients with suspected sarcopenia. 47.5% used their clinical view as Diagnostic strategy. Handgrip strength was the most frequently used objective Diagnostic measure (33.9%). Five months after attendance, reported use of Diagnostic tests was increased, i.e. handgrip strength up to 67.4%, gait speed up to 72.1% and muscle mass up to 20.9%. Bottlenecks during implementation of the Diagnostic strategy were experienced by 67.1%; lack of awareness among other healthcare professionals, acquisition of Equipment and time constraints to perform the Diagnostic measures were reported most often. Before attendance, 36.4% stated not to consult a physiotherapists or exercise therapists (PT/ET) or dietitian for sarcopenia interventions, 10.5% consulted a PT/ET, 32.7% a dietitian and 20.5% both a PT/ET and dietitian. Five months after attendance, these percentages were 28.3%, 21.7%, 30.0% and 20.0% respectively. Conclusion The concept of sarcopenia is familiar to most Dutch healthcare professionals but application in practice is hampered, mostly by lack of knowledge, availability of Equipment, time constraints and lack of collaboration.
Lia Bittencourt - One of the best experts on this subject based on the ideXlab platform.
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validation of a portable monitoring system for the diagnosis of obstructive sleep apnea syndrome
Sleep, 2009Co-Authors: Rogerio Santossilva, Denis Eduardo Sartori, Viviane Truksinas, Eveli Truksinas, Fabiana Fernanda Alonso, Sergio Tufik, Lia BittencourtAbstract:THE CURRENT STANDARDS OF PRACTICE FOR DIAGNOSING OBSTRUCTIVE SLEEP APNEA (OSA) REQUIRE OVERNIGHT IN-LABORATORY POLYSOMNOGRAPHY (PSG).1 This conventional approach has been considered costly and technically complex and may present scheduling difficulties when there is high demand. Other approaches considered for their potential to reduce costs and increase accessibility have also been evaluated.2 Portable monitoring (PM) Equipment including at least 4 channels (airflow, respiratory movements, oxyhemoglobin saturation [SpO2] and heart rate) is classified as a type 3 portable monitor3 and has been utilized as an alternative Diagnostic test for OSA in patients with a high pre-test probability of OSA.2 Previous research has reported the equivalence of PM to PSG. Studies comparing PM with PSG have been performed on different nights.4–7 Studies simultaneously evaluating PM and PSG have been conducted using simplified PMs without the recommended 4 channels to meet the type 3 criteria,8–12 while others compared type 3 PM with PSG simultaneously.13–20 Type 3 monitors were recommended for use in attended settings if recordings were manually reviewed and patients with comorbid conditions were excluded.4 Additionally, symptomatic patients with negative PM results were recommended to have an in-laboratory evaluation with full-night attended PSG.21 The use of PM for continuous positive airway pressure (CPAP) titration or a split night protocol has not been recommended.21,22 In 2004, the Center of Medicare and Medicaid Services (CMS) reviewed its national coverage determination (NCD) (#240.4) regarding the use of PM as a basis for prescribing CPAP. The use of PM remained uncovered by insurance23 until recently, when CMS released its proposed decision for modification of NCD 240.4, which now includes PM.24 The American Academy of Sleep Medicine (AASM)2 recently published clinical guidelines for the use of unattended PM in the diagnosis of OSA and concluded that unattended PM should be performed only (1) in conjunction with a comprehensive sleep evaluation, supervised by a practitioner with qualifications for certification in sleep medicine; (2) in patients with a high pretest probability of moderate to severe OSA (without comorbid conditions or other sleep disorders); (3) in patients for whom in-lab PSG is not possible by virtue of immobility, safety, or critical illness; and (4) to monitor the response to non-CPAP treatment for OSA. Thus, there is still a need to evaluate simple and accurate home Diagnostic Equipment for reliability and accuracy in diagnosing OSA. The aim of the present study was to demonstrate that a type 3 PM device (Stardust II, Respironics, Inc., USA) would generate AHI values similar to in-laboratory PSG for diagnosis of OSA in a randomized, prospective trial. Comparisons of the PM results were made both with and without simultaneous PSG.