Clinical evaluation of chirp-coded excitation in medical ultrasound

Pedersen, Morten Høgholm; Misaridis, T.; Jensen, Jørgen Arendt

doi:10.1016/s0301-5629(02)00784-6

Cited by 100 publications

(59 citation statements)

References 7 publications

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“…A hypothesized imaging scheme could exploit any differences in the response to these excitations. Chirped excitation has been investigated in order to increase the signal-to-noise ratio (SNR) with [13][14][15] and without [16][17][18] contrast agents, however, long pulses also increase the effect of diffusion on the microbubble. The new simultaneous optical and acoustical system for observation of microbubbles was used here to evaluate the nonlinear components in the received echoes, the similarities and differences between echoes from increasing and decreasing frequency excitation, and the effect of diffusion on the quality of the predicted echoes.…”

Section: Nih Public Accessmentioning

confidence: 99%

Observation of contrast agent response to chirp insonation with a simultaneous optical-acoustical system

Sun¹,

Zhao²,

Dayton³

et al. 2006

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Rayleigh-Plesset analysis, ultra-high speed photography, and single bubble acoustical recordings have previously been applied independently to characterize the radial oscillation and resulting echoes from a microbubble in response to an ultrasonic pulse. In addition, high speed photography has shown that microbubbles are destroyed over a single pulse or pulse train by diffusion and fragmentation. In order to develop a single model to characterize microbubble echoes based on oscillatory and destructive characteristics, an optical-acoustical system was developed to simultaneously record the optical image and backscattered echo from each microbubble. Combined observation provides the opportunity to compare predictions for oscillation and echoes with experimental results and identify discrepancies due to diffusion or fragmentation. Optimization of agents and insonating pulse parameters may be facilitated with this system. The mean correlation of the predicted and experimental radius-time curves and echoes exceeds 0.7 for the parameters studied here. An important application of this new system is to record and analyze microbubble response to a long pulse where diffusion is shown to occur over the pulse duration. The microbubble response to an increasing or decreasing chirp is evaluated using this new tool. For chirp insonation beginning with the lower center frequency, low frequency modulation of the oscillation envelope was obvious. However, low frequency modulation was not observed in the radial oscillation produced by decreasing chirp insonation. Comparison of the echoes from similar sized microbubbles following increasing and decreasing chirp insonation demonstrated that the echoes were not time-reversed replicas. Using a transmission pressure of 620 kPa, the −6 dB echo length was 0.9 and 1.1 μs for increasing and decreasing chirp insonation, respectively (P = 0.02). The mean power in the low frequency portion of the echoes was 8 (mV) 2 and 13 (mV) 2 for increasing and decreasing chirp insonation, respectively, (P = 0.01).

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Section: Nih Public Accessmentioning

confidence: 99%

Observation of contrast agent response to chirp insonation with a simultaneous optical-acoustical system

Sun¹,

Zhao²,

Dayton³

et al. 2006

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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“…Chirp-encoded excitation, in particular, is suitable for constructing time-localized signals through regions containing high attenuation due to its spectral similarity to a broadband pulse (Pedersen et al 2003). This method calculates the cross-correlation between the transmitted and received chirp signals, producing localized pulses in time corresponding to scattering locations.…”

Section: Introductionmentioning

confidence: 99%

“…Experiments are performed in both longitudinal and shear modes. To evaluate the multi-cycle coding scheme, the measurements are compared with a broadband (pulsed) signal as well as with the linear frequency modulated chirp (Pedersen et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Spectral image reconstruction for transcranial ultrasound measurement

Clement

2005

Phys. Med. Biol.

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An approach aimed at improved ultrasound resolution and signal strength through highly attenuating media is presented. The method delivers a series of multiple-cycle bursts in order to construct a discrete spectral (frequency domain) response in one dimension. Cross-correlation of this ultrasound A-mode response with its transmitted signal results in time-localized peaks that correspond to scattering locations. The approach is particularly relevant to the problem of transcranial ultrasound imaging, as it combines numerous smaller signals into a single signal whose net power may exceed that which could be achieved using a single burst. Tests are performed with human skull fragments and nylon-wire targets embedded in a tissue phantom. Skulls are oriented to produce both lateral and shear modes of transcranial propagation. A total of 9 locations distributed over three ex vivo human skull samples are studied. Compared with pulsed and chirped signals, results indicate more localized peaks when using the multi-cycle approach, with more accurate positioning when combined with the transcranial shear mode.

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“…Modulated ultrasound has been successfully used in medical ultrasound, mostly in medical imaging as a technique to enhance signal to noise ratio. [27][28][29][30] However, it is still a new signal modality in bone measurement. Literatures search showed that only a few studies used ultrasound signals other than broadband pulse in the bone measurement.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the trabecular bone structure using frequency modulated ultrasound pulse

Lin

Xia

Qin

2009

The Journal of the Acoustical Society of America

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The objective of this study was to investigate the efficacy of modulated ultrasound signals in the measurement of bone properties as an early indicator of osteoporosis. Twenty-one trabecular bone cubes were harvested from sheep femoral condyles and the cube axes corresponded to the anatomic superior-inferior ͑SI͒, antero-posterior ͑AP͒, and medio-lateral ͑ML͒ orientations. Micro-CT measurements were made on those samples to obtain bone volume fraction ͑BV/TV͒, trabecular thickness ͑Tb.Th͒, and trabecular separation ͑Tb.Sp͒. Ultrasound tests were performed in the three orthogonal orientations using pulse and frequency modulated ultrasound. The comparison of the frequency modulated attenuation ͑FMA͒ with the broadband ultrasound attenuation ͑BUA͒ was made within the frequency band between 300 and 700 kHz. Results showed that FMA demonstrated higher correlations to the trabecular structure properties in the SI orientation ͑R 2 = 0.84 for BV/TV, R 2 = 0.77 for Tb.Th, R 2 = 0.7 for Tb.Sp͒ than BUA ͑R 2 = 0.30 for BV/TV, R 2 = 0.27 for Tb.Th, R 2 = 0.33 for Tb.Sp͒. In the AP orientation, FMA had higher correlation to Tr.Sp ͑R 2 = 0.64͒ than BUA ͑R 2 = 0.48͒, and relatively lower correlation to BV/TV ͑R 2 = 0.48͒ and Tb.Th ͑R 2 = 0.31͒ than BUA ͑R 2 = 0.64 for BV/TV and R 2 = 0.58 for Tb.Th͒. The results suggested that FMA could be a new ultrasound index for bone properties assessment.

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Clinical evaluation of chirp-coded excitation in medical ultrasound

Cited by 100 publications

References 7 publications

Observation of contrast agent response to chirp insonation with a simultaneous optical-acoustical system

Observation of contrast agent response to chirp insonation with a simultaneous optical-acoustical system

Spectral image reconstruction for transcranial ultrasound measurement

Characterization of the trabecular bone structure using frequency modulated ultrasound pulse

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