Transcranial focused ultrasound is a booming noninvasive therapy for brain stimuli. The Kelvin–Voigt equations are employed to calculate the sound field created by focusing a 256-element planar phased array through a...Transcranial focused ultrasound is a booming noninvasive therapy for brain stimuli. The Kelvin–Voigt equations are employed to calculate the sound field created by focusing a 256-element planar phased array through a monkey skull with the time-reversal method. Mode conversions between compressional and shear waves exist in the skull. Therefore, the wave field separation method is introduced to calculate the contributions of the two waves to the acoustic intensity and the heat source, respectively. The Pennes equation is used to depict the temperature field induced by ultrasound. Five computational models with the same incident angle of 0？and different distances from the focus for the skull and three computational models at different incident angles and the same distance from the focus for the skull are studied. Numerical results indicate that for all computational models, the acoustic intensity at the focus with mode conversions is 12.05%less than that without mode conversions on average. For the temperature rise, this percentage is 12.02%. Besides, an underestimation of both the acoustic intensity and the temperature rise in the skull tends to occur if mode conversions are ignored. However, if the incident angle exceeds 30？, the rules of the over-and under-estimation may be reversed. Moreover,shear waves contribute 20.54% of the acoustic intensity and 20.74% of the temperature rise in the skull on average for all computational models. The percentage of the temperature rise in the skull from shear waves declines with the increase of the duration of the ultrasound.展开更多
AIM: To experimentally investigate the acoustical behavior of different dual-mode nanosized contrast agents(NPCAs) for echographic medical imaging at low ultrasound(US) frequency. METHODS: We synthesized three differe...AIM: To experimentally investigate the acoustical behavior of different dual-mode nanosized contrast agents(NPCAs) for echographic medical imaging at low ultrasound(US) frequency. METHODS: We synthesized three different nanosized structures:(1) Pure silica nanospheres(SiNSs);(2) FePt-iron oxide(FePt-IO)-coated SiNSs; and(3) IOcoated SiNSs, employing three different diameter of SiNS-core(160, 330 and 660 nm). Tissue mimicking phantoms made of agarose gel solution containing 5 mg of different NPCAs in 2 mL-Eppendorf tubes, were insonified by a commercial echographic system at three different low US pulse values(2.5, 3.5 and 4.5 MHz). The raw radiofrequency signal, backscattered from each considered NPCA containing sample, has been processed in order to calculate the US average backscatter intensity and compare the acoustic behavior of the different NPCA types. RESULTS: The highest US contrast was exhibited by pure SiNSs; FePt-IO-coated SiNSs acoustical behavior followed a similar trend of pure SiNSs with a slight difference in terms of brightness values. The acoustic response of the examined NPCAs resulted function of both SiNS diameter and US frequency. Specifically, higher US frequencies determined higher value of the backscatter for a given SiNS diameter. Frequencydependent enhancement was marked for pure SiNSs and became less remarkable for FePt-IO-coated SiNSs, whereas IO-coated SiNSs resulted almost unaffected by such frequency variations. Pure and FePt-IO-coated SiNSs evidenced an image backscatter increasing with the diameter up to 330 nm. Conversely, among the types of NPCA tested, IO-coated SiNSs showed the lowest acoustical response for each synthesized diameter and employed US frequency, although a diameter-dependent raising trend was evidenced. CONCLUSION: The US characterization of magnetically covered SiNS shows that FePt-IO, rather than IO, was the best magnetic coating for realizing NPCAs suitable for dual mode imaging of deep organs, combining US and magnetic resonance imaging.展开更多
This paper deals with the temperature correlation of gray scale of B-mode ultrasound image from heated tissue. In this study, many in-vitro fresh pig livers are heated in a temperature range from 28 ℃ to 45℃, from w...This paper deals with the temperature correlation of gray scale of B-mode ultrasound image from heated tissue. In this study, many in-vitro fresh pig livers are heated in a temperature range from 28 ℃ to 45℃, from which a series of B-mode ultrasonic images of livers were obtained. The gray-value is evaluated from the ultrasound images respectively. A correlation of the mean gray value of the selected regions (12×12 pixels) in B-mode ultrasonic images of liver and its temperature was pointed out. And the experiment results agreed the evaluation well. And it is possible to monitor the tissue temperature changing in hyperthermia using this correlation.展开更多
In this study, the performance of chirplet signal decomposition (CSD) and empirical mode decomposition (EMD) coupled with Hilbert spectrum have been evaluated and compared for ultrasonic imaging applications. Numerica...In this study, the performance of chirplet signal decomposition (CSD) and empirical mode decomposition (EMD) coupled with Hilbert spectrum have been evaluated and compared for ultrasonic imaging applications. Numerical and experimental results indicate that both the EMD and CSD are able to decompose sparsely distributed chirplets from noise. In case of signals consisting of multiple interfering chirplets, the CSD algorithm, based on successive search for estimating optimal chirplet parameters, outperforms the EMD algorithm which estimates a series of intrinsic mode functions (IMFs). In particular, we have utilized the EMD as a signal conditioning method for Hilbert time-frequency representation in order to estimate the arrival time and center frequency of chirplets in order to quantify the ultrasonic signals. Experimental results clearly exhibit that the combined EMD and CSD is an effective processing tools to analyze ultrasonic signals for target detection and pattern recognition.展开更多
目的研究将基于影像归档和通信(Picture Archiving and Communication System,PACS)系统与以案例为基础的学习(Case-based Learning,CBL)相结合的教学模式用于超声诊断实践教学中的效果。方法选取2022年7月—2024年1月于齐齐哈尔医学院...目的研究将基于影像归档和通信(Picture Archiving and Communication System,PACS)系统与以案例为基础的学习(Case-based Learning,CBL)相结合的教学模式用于超声诊断实践教学中的效果。方法选取2022年7月—2024年1月于齐齐哈尔医学院附属第一医院进行实习的48名影像学专业本科生为研究对象,按带教方法不同分为对照组和观察组,各24名。对照组行传统带教法,观察组行基于PACS系统联合CBL教学模式。比较两组实践成绩(理论成绩、阅片成绩)、积极学习主动性(学习驱动力、学习目标、深入学习、控制学习、扎实学习)以及教学效果(激发学习兴趣、提高学习效率、提高临床思维能力、提高表达能力、调动课堂教学氛围)。结果观察组理论成绩为(45.30±0.86)分阅片成绩为为(45.18±0.90)分均高于对照组的(40.89±1.26)分、(41.11±1.17)分,差异有统计学意义(t=14.162、13.507,P均<0.05)。观察组积极学习主动性评分以及教学效果评分均高于对照组,差异有统计学意义(P均<0.05)。结论在超声诊断学实践教学中采取基于PACS系统联合CBL教学模式可提高实习生超声诊断教学成绩、积极学习主动性,从而提高教学效果。展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.81527901,11604361,and 91630309)
文摘Transcranial focused ultrasound is a booming noninvasive therapy for brain stimuli. The Kelvin–Voigt equations are employed to calculate the sound field created by focusing a 256-element planar phased array through a monkey skull with the time-reversal method. Mode conversions between compressional and shear waves exist in the skull. Therefore, the wave field separation method is introduced to calculate the contributions of the two waves to the acoustic intensity and the heat source, respectively. The Pennes equation is used to depict the temperature field induced by ultrasound. Five computational models with the same incident angle of 0？and different distances from the focus for the skull and three computational models at different incident angles and the same distance from the focus for the skull are studied. Numerical results indicate that for all computational models, the acoustic intensity at the focus with mode conversions is 12.05%less than that without mode conversions on average. For the temperature rise, this percentage is 12.02%. Besides, an underestimation of both the acoustic intensity and the temperature rise in the skull tends to occur if mode conversions are ignored. However, if the incident angle exceeds 30？, the rules of the over-and under-estimation may be reversed. Moreover,shear waves contribute 20.54% of the acoustic intensity and 20.74% of the temperature rise in the skull on average for all computational models. The percentage of the temperature rise in the skull from shear waves declines with the increase of the duration of the ultrasound.
基金Supported by Italian Ministry of Instruction and Research,No.DM18604-Bando Laboratori-DD MIUR 14.5.2005 n.602/Ric/2005FESR PO Apulia Region 2007-2013-Action 1.2.4,No.3Q5AX31the Progetto Bandiera NANOMAX ENCODER
文摘AIM: To experimentally investigate the acoustical behavior of different dual-mode nanosized contrast agents(NPCAs) for echographic medical imaging at low ultrasound(US) frequency. METHODS: We synthesized three different nanosized structures:(1) Pure silica nanospheres(SiNSs);(2) FePt-iron oxide(FePt-IO)-coated SiNSs; and(3) IOcoated SiNSs, employing three different diameter of SiNS-core(160, 330 and 660 nm). Tissue mimicking phantoms made of agarose gel solution containing 5 mg of different NPCAs in 2 mL-Eppendorf tubes, were insonified by a commercial echographic system at three different low US pulse values(2.5, 3.5 and 4.5 MHz). The raw radiofrequency signal, backscattered from each considered NPCA containing sample, has been processed in order to calculate the US average backscatter intensity and compare the acoustic behavior of the different NPCA types. RESULTS: The highest US contrast was exhibited by pure SiNSs; FePt-IO-coated SiNSs acoustical behavior followed a similar trend of pure SiNSs with a slight difference in terms of brightness values. The acoustic response of the examined NPCAs resulted function of both SiNS diameter and US frequency. Specifically, higher US frequencies determined higher value of the backscatter for a given SiNS diameter. Frequencydependent enhancement was marked for pure SiNSs and became less remarkable for FePt-IO-coated SiNSs, whereas IO-coated SiNSs resulted almost unaffected by such frequency variations. Pure and FePt-IO-coated SiNSs evidenced an image backscatter increasing with the diameter up to 330 nm. Conversely, among the types of NPCA tested, IO-coated SiNSs showed the lowest acoustical response for each synthesized diameter and employed US frequency, although a diameter-dependent raising trend was evidenced. CONCLUSION: The US characterization of magnetically covered SiNS shows that FePt-IO, rather than IO, was the best magnetic coating for realizing NPCAs suitable for dual mode imaging of deep organs, combining US and magnetic resonance imaging.
基金The research was supported by National Nature Science Foundation (30470450) Education Committee Foundation( KP0608200201 ) Elitist Foundation( KW5800200351 ) from Beijing City,China.
文摘This paper deals with the temperature correlation of gray scale of B-mode ultrasound image from heated tissue. In this study, many in-vitro fresh pig livers are heated in a temperature range from 28 ℃ to 45℃, from which a series of B-mode ultrasonic images of livers were obtained. The gray-value is evaluated from the ultrasound images respectively. A correlation of the mean gray value of the selected regions (12×12 pixels) in B-mode ultrasonic images of liver and its temperature was pointed out. And the experiment results agreed the evaluation well. And it is possible to monitor the tissue temperature changing in hyperthermia using this correlation.
文摘In this study, the performance of chirplet signal decomposition (CSD) and empirical mode decomposition (EMD) coupled with Hilbert spectrum have been evaluated and compared for ultrasonic imaging applications. Numerical and experimental results indicate that both the EMD and CSD are able to decompose sparsely distributed chirplets from noise. In case of signals consisting of multiple interfering chirplets, the CSD algorithm, based on successive search for estimating optimal chirplet parameters, outperforms the EMD algorithm which estimates a series of intrinsic mode functions (IMFs). In particular, we have utilized the EMD as a signal conditioning method for Hilbert time-frequency representation in order to estimate the arrival time and center frequency of chirplets in order to quantify the ultrasonic signals. Experimental results clearly exhibit that the combined EMD and CSD is an effective processing tools to analyze ultrasonic signals for target detection and pattern recognition.
文摘目的研究将基于影像归档和通信(Picture Archiving and Communication System,PACS)系统与以案例为基础的学习(Case-based Learning,CBL)相结合的教学模式用于超声诊断实践教学中的效果。方法选取2022年7月—2024年1月于齐齐哈尔医学院附属第一医院进行实习的48名影像学专业本科生为研究对象,按带教方法不同分为对照组和观察组,各24名。对照组行传统带教法,观察组行基于PACS系统联合CBL教学模式。比较两组实践成绩(理论成绩、阅片成绩)、积极学习主动性(学习驱动力、学习目标、深入学习、控制学习、扎实学习)以及教学效果(激发学习兴趣、提高学习效率、提高临床思维能力、提高表达能力、调动课堂教学氛围)。结果观察组理论成绩为(45.30±0.86)分阅片成绩为为(45.18±0.90)分均高于对照组的(40.89±1.26)分、(41.11±1.17)分,差异有统计学意义(t=14.162、13.507,P均<0.05)。观察组积极学习主动性评分以及教学效果评分均高于对照组,差异有统计学意义(P均<0.05)。结论在超声诊断学实践教学中采取基于PACS系统联合CBL教学模式可提高实习生超声诊断教学成绩、积极学习主动性,从而提高教学效果。
