The measurement of backscatter coefficient from a broadband pulse-echo system: a new formulation

Chen, Xucai; Phillips, Daniel; Schwarz, Karl Q.; Mottley, Jack G.; Parker, Kevin J.

doi:10.1109/58.585136

Cited by 122 publications

(25 citation statements)

References 8 publications

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“…Eleven equally spaced slices were imaged for each sample, and the number of A-lines per sample varied depending on the transducer frequency and sample size. The BSC was estimated from the RF data using a planar reference method [39] to remove equipment-dependent effects. To generate a BSC versus frequency curve for a sample scanned by a single transducer, 1) a BSC estimate was made for each ROI based on the gated RF echo data from that ROI; 2) a mean BSC was estimated for each of the 11 slices by averaging the BSCs from all the ROIs within that slice; and 3) the 11 mean BSCs were averaged.…”

Section: Methodsmentioning

confidence: 99%

Structure function for high-concentration biophantoms of polydisperse scatterer sizes

Han

O’Brien

2015

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

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Ultrasonic backscattering coefficient (BSC) has been used extensively to characterize tissue. In most cases, sparse scatterer concentrations are assumed. However, many types of tissues have dense scattering media. This study addresses the problem of dense media scattering by taking into account the correlation among scatterers using the structure functions. The effect of scatterer polydispersity on the structure functions is investigated. Structure function models based on polydisperse scatterers are theoretically developed and experimentally evaluated against the structure functions obtained from cell pellet biophantoms. The biophantoms were constructed by placing live cells of known concentration in coagulation media to form a clot. The BSCs of the biophantoms were estimated using single-element transducers over the frequency range from 11 to 105 MHz. Experimental structure functions were obtained by comparing the BSCs of two cell concentrations. The structure functions predicted by the models agreed with the experimental structure functions. Fitting the models yielded cell radius estimates that were consistent with direct light microscope measures. The results demonstrate the role of scatterer position correlation on dense media scattering, and the significance of scatterer polydispersity on structure functions. This work may lead to more accurate modeling of ultrasonic scattering in dense medium for improved tissue characterization.

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Section: Methodsmentioning

confidence: 99%

Structure function for high-concentration biophantoms of polydisperse scatterer sizes

Han

O’Brien

2015

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

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“…From each data block the backscatter coefficient versus frequency was estimated by the method of Chen et al [1997] and based on studies by Lavarello et al [2011]. For calculation of the backscatter coefficient, a reference spectrum for each depth location was acquired by measuring the signal reflected from a smooth planar surface of known reflectivity (Plexiglas).…”

Section: Methodsmentioning

confidence: 99%

Characterization of Thyroid Cancer in Mouse Models Using High-Frequency Quantitative Ultrasound Techniques

Lavarello

Ridgway

Sarwate

et al. 2013

Ultrasound in Medicine & Biology

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Currently, the evaluation of thyroid cancer relies on the use of fine needle aspiration biopsy as non-invasive imaging methods do not provide sufficient levels of accuracy for the diagnosis of this disease. In this study, the potential of quantitative ultrasound methods for characterizing thyroid tissues was studied using a rodent model ex vivo. A high-frequency ultrasonic scanning system (40 MHz) was used to scan thyroids extracted from mice that had spontaneously developed thyroid lesions (cancerous or benign). Three sets of mice were acquired having different predispositions to developing thyroid anomalies (a C-cell adenoma, a papillary thyroid carcinoma (PTC), and a follicular variant papillary thyroid carcinoma (FV-PTC)). A fourth set of mice did not develop thyroid anomalies (normal mice) and were used as controls. The backscatter coefficient was estimated from excised thyroid lobes for the different mice. From the backscatter coefficient versus frequency (25 to 45 MHz), the effective scatterer diameter (ESD) and effective acoustic concentration (EAC) were estimated. From the envelope of the backscattered signal, the homodyned K distribution was used to estimate the k parameter (ratio of coherent to incoherent signal energy) and the μ parameter (number of scatterers per resolution cell). Statistically significant differences were observed between the malignant thyroids and the normal thyroids based on the ESD, EAC and μ parameters. The mean values of the ESDs were 18.0 ± 0.92, 15.9 ± 0.81, and 21.5 ± 1.80 µm for the PTC, FV-PTC and the normal thyroids, respectively. The mean values of the EACs were 59.4 ± 1.74, 62.7 ± 1.61, and 52.9 ± 3.42 dB (mm−3) for the PTC, FV-PTC and the normal thyroids, respectively. The mean values of the μ parameters were 2.55 ± 0.37, 2.59 ± 0.43, and 1.56 ± 0.99 for the PTC, FV-PTC and the normal thyroids, respectively. Statistically significant differences were observed between the malignant thyroids and the C-cell adenomas based on the ESD and EAC parameters with estimated values for the ESD of 21.3 ± 1.50 µm and EAC of 54.7 ± 2.24 dB (mm−3) for the C-cell adenomas. These results suggest that high frequency quantitative ultrasound may enhance the ability to detect and classify diseased thyroid tissues.

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“…Since the target is placed in focal point of the laser, and the diameter of the laser spot is negligible compared to aperture of the transducer, diffraction of PA signal originated from the target and detected by a focused transducer can be expressed as [15,16]…”

Section: Theorymentioning

confidence: 99%

Measuring non-radiative relaxation time of fluorophores with biomedical applications by intensity-modulated laser-induced photoacoustic effect

Soroushian¹,

Yang²

2011

Biomed. Opt. Express

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Modulated tone-burst light was employed to measure non-radiative relaxation time of fluorophores with biomedical importance through photoacoustic effect. Non-radiative relaxation time was estimated through the frequency dependence of photoacoustic signal amplitude. Experiments were performed on solutions of new indocyanine green (IR-820), which is a near infrared dye and has biomedical applications, in two different solvents (water and dimethyl sulfoxide (DMSO)). A 1.5 times slower non-radiative relaxation for the solution of dye in DMSO was observed comparing with the aqueous solution. This result agrees well with general finding that non-radiative relaxation of molecules in triplet state depends on viscosity of solvents in which they are dissolved. Measurements of the non-radiative relaxation time can be used as a new source of contrast mechanism in photoacoustic imaging technique. The proposed method has potential applications such as imaging tissue oxygenation and mapping of other chemophysical differences in microenvironment of exogenous biomarkers.

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The measurement of backscatter coefficient from a broadband pulse-echo system: a new formulation

Cited by 122 publications

References 8 publications

Structure function for high-concentration biophantoms of polydisperse scatterer sizes

Structure function for high-concentration biophantoms of polydisperse scatterer sizes

Characterization of Thyroid Cancer in Mouse Models Using High-Frequency Quantitative Ultrasound Techniques

Measuring non-radiative relaxation time of fluorophores with biomedical applications by intensity-modulated laser-induced photoacoustic effect

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