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BRL Abstracts Database |
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Your search for ultrasound produced 3296 results. Page 211 out of 330
| Title |
Quantitative ultrasound assessment of breast cancer using a multiparameter approach. |
| Author |
Oelze ML, O'Brien WD Jr, Zachary JF. |
| Journal |
Proc Ultrason Symp IEEE |
| Volume |
|
| Year |
2007 |
| Abstract |
Abstract—Early detection and diagnosis of breast cancer leads to
improved prognosis. Quantitative ultrasound (QUS) techniques
utilizing a multiparameter set have been developed for classifying
rodent models of breast cancer. The improvement in detection
and diagnosis of breast cancer using QUS will have significant
medical impact. Two kinds of mammary tumors, carcinoma and
sarcoma, were examined in mice using QUS imaging. Ten tumors
for each kind of cancer were scanned with a 20-MHz singleelement
transducer (f/3). The tumors contained microstructural
differences in size, shape, and organizational patterns of the
scatterers. Cells were identified as a prominent source of
scattering in the tumors. The average scatterer diameter (ASD)
and average acoustic concentration (AAC) were estimated by
comparing the normalized backscattered power spectra from the
tumors with newly developed models of cell scattering. The
organizational structure of the tumors was also characterized by
a clustering parameter (the β parameter) and the randomness of
the scatterer locations (the S parameter) by comparing the
envelope statistics of the backscatter to a homodyned-K
distribution. F-tests conducted on the backscattered power
spectra from the two kinds of tumors revealed statistically
significant differences for frequencies above 16 MHz. QUS
images of the tumors utilizing the ASD, AAC, β, and S parameter
estimates from the new model and the envelope statistics were
constructed. Statistically significant differences were observed
between the carcinomas and sarcomas for all estimated
parameters for ultrasonic frequencies above 16 MHz. Feature
analysis plots incorporating all four parameters indicated cancer
classification was improved compared with analysis using only
two parameters. High-frequency QUS utilizing a multiparameter
feature set improved the diagnostic potential of ultrasound for
breast cancer detection. (Supported by NIH Grants CA 079179
and CA111289) |
| Title |
Quantitative ultrasound assessment of cervical microstructure. |
| Author |
Feltovich H, Nam K, Hall TJ. |
| Journal |
Ultrason Imaging |
| Volume |
|
| Year |
2010 |
| Abstract |
The objective of this preliminary study was to determine whether quantitative ultrasound (QUS) can provide insight into, and characterization of, uterine cervical microstructure. Throughout pregnancy, cervical collagen reorganizes (from aligned and anisotropic to disorganized and isotropic) as the cervix changes in preparation for delivery. Premature changes in collagen are associated with premature birth in mammals. Because QUS is able to detect structural anisotropy/isotropy, we hypothesized that it may provide a means of noninvasively assessing cervical microstructure. Thorough study of cervical microstructure has been limited by lack of technology to detect small changes in collagen organization, which has in turn limited our ability to detect abnormal and/or premature changes in collagen that may lead to preterm birth. In order to determine whether QUS may be useful for detection of cervical microstructure, radiofrequency (rf) echo data were acquired from the cervices of human hysterectomy specimens (n = 10). The angle between the acoustic beam and tissue was used to assess anisotropic acoustic propagation by control of transmit/receive angles from -20 degrees to +20 degrees. The power spectrum of the echo signals from within a region of interest was computed in order to investigate the microstructure of the tissue. An identical analysis was performed on a homogeneous phantom with spherical scatterers for system calibration. Power spectra of backscattered rf from the cervix were 6 dB higher for normal (0 degree) than steered (+/- 20 degrees) beams. The spectral power for steered beams decreased monotonically (0.4 dB at +5 degrees to 3.6 dB at +20 degrees). The excess difference (compared to similar analysis for the phantom) in normally-incident (0 degree) versus steered beams is consistent with scattering from an aligned component of the cervical microstructure. Therefore, QUS appears to reliably identify an aligned component of cervical microstructure; because collagen is ubiquitously and abundantly present in the cervix, this is the most likely candidate. Detection of changes in cervical collagen and microstructure may provide information about normal versus abnormal cervical change and thus guide development of earlier, more specific interventions for preterm birth. |
| Title |
Quantitative ultrasound assessment of HIFU induced lesions in rodent liver. |
| Author |
Kemmerer J, Ghoshal G, Oelze M. |
| Journal |
IEEE Int Ultrasonics Symp Proc |
| Volume |
|
| Year |
2010 |
| Abstract |
Quantitative ultrasound (QUS) techniques have been used for tissue characterization by discriminating between tissues of differing microstructure. High Intensity Focused Ultrasound (HIFU) is a means for minimal or non-invasive therapy, which results in changes in tissue microstructure. However, significant
challenges remain for the monitoring and assessment of HIFU therapy. Conventional B-mode imaging is not reliable for detection and assessment of thermal lesions produced by HIFU. Because of QUS sensitivity to microstructure changes, it was
hypothesized that QUS could assess thermal lesions. A 1-MHz single-element focused transducer (f/1.1) was used to produce thermal lesions in ex-vivo rat liver. The focal intensities used to generate lesions were measured to be between 1500 and 2500 W/cm2 in degassed water using a calibrated needle hydrophone.
These exposures were monitored using a clinical ultrasound array (L14-5, Ultrasonix). Treated and untreated regions as determined by histology and visual inspection were compared to parametric images of QUS parameters (Effective Scatterer Diameter (ESD), and Effective Acoustic Concentration (EAC)).An average increase in ESD of 15% was observed in three samples, while EAC estimates decreased by 4.3 dB. These findings suggest that QUS can be used for non-invasive
assessment of thermal lesions. |
| Title |
Quantitative ultrasound assessment of the rat cervix. |
| Author |
McFarlin BL, O'Brien WD Jr, Oelze ML, Zachary JF, White-Traut RC. |
| Journal |
J Ultrasound Med |
| Volume |
|
| Year |
2006 |
| Abstract |
Objective. The purpose of this research was to detect cervical ripening with a new quantitative ultrasound technique. Methods. Cervices of 13 nonpregnant and 65 timed pregnant (days 15, 17, 19, 20, and 21 of pregnancy) Sprague Dawley rats were scanned ex vivo with a 70-MHz ultrasound transducer. Ultrasound scatterer property estimates (scatterer diameter [SD], acoustic concentration [AC], and scatterer strength factor [SSF]) from the cervices were quantified and then compared to hydroxyproline and water content. Insertion loss (attenuation) was measured in 3 rats in each of the 6 groups. Discriminant analysis was used to predict gestational age group (cervical ripening) from the ultrasound variables SD, SSF, and AC. Results. Differences were observed between the groups (SD, AC, and SSF; P < .0001). Quantitative ultrasound measures changed as the cervix ripened: (1) SD increased from days 15 to 21; (2) AC decreased from days 15 to 21; and (3) SSF was the greatest in the nonpregnant group and the least in the day 21 group. Cervix hydroxyproline content increased as pregnancy progressed (P < .003) and correlated with group, SD, AC, and SSF (P < .001). Discriminant analysis of ultrasound variables predicted 56.4% of gestational group assignment (P < .001) and increased to 77% within 2 days of the predicted analysis. Cervix insertion loss was greatest for the nonpregnant group and least for the day 21 group. Conclusions. Quantitative ultrasound predicted cervical ripening in the rat cervix, but before use in humans, quantitative ultrasound will need to predict gestational age in the later days of gestation with more precision. |
| Title |
Quantitative ultrasound assessment of the rat cervix. |
| Author |
McFarlin B. |
| Journal |
Thesis(PhD): Univ of Illinois Chicago |
| Volume |
|
| Year |
2005 |
| Abstract |
The birth of a healthy baby is the expectation of every mother and family as they
anticipate the birth of their new family member. It is the beginning of a new future and a potential of a new human being. As Blake noted in his poem, it has been an expectation that has been anticipated by families throughout history (Blake, 1982). It is not only the expectation of the mother and family, but the birth of a healthy baby at term is also the goal of midwives and obstetric health providers when providing prenatal care (Cunningham, Leveno, MacDonald, Gant, & Gilstrap, 1993). The importance of starting life healthy not only has value for individuals and families but also for societies.Societies need productive members who can contribute to the growth and well-being of
the society. |
| Title |
Quantitative ultrasound assessment of thermal damage in excised liver |
| Author |
Kemmerer JP, Ghoshal G, Oelze ML |
| Journal |
AIP Conf Proc |
| Volume |
|
| Year |
2012 |
| Abstract |
Quantitative ultrasound (QUS) is a novel approach for characterizing tissue
microstructure and changes in tissue microstructure due to therapy. In this report, we discuss changes in QUS parameters in liver tissues after being exposed to thermal insult. Effective scatterer diameter (ESD) and effective acoustic
concentration (EAC) from the normalized backscattered power spectrum were examined in ra t liver specimens heated in a degassed saline bath. Individual liver samples were bisected, with half of each sample heated to a therapeutic
temperature of 60 °C for 10 minutes and the other half held at 37 °C. The ultrasonic backscatter and attenuation coefficient were then estimated at 37 °C from both halves. ESD was observed to decrease by an average of 34% in exposed co
mpared to unexposed sample sections, EAC increased by 18 dB, and the attenuation coefficient increased by 70%. Histological slides from these samples indicate cell size and/or concentration may be affected by heating. This work was
supported by NIH R01-EB008992. |
| Title |
Quantitative ultrasound assessment of thermal damage in excised liver |
| Author |
Kemmer JP, Ghoshal G, Oelze ML. |
| Journal |
11th Int Symp on Therapeutic Ultrasound |
| Volume |
|
| Year |
2012 |
| Abstract |
Quantitative ultrasound (QUS) is a novel approach for characterizing tissue
microstructure and changes in tissue microstructure due to therapy. In this report, we discuss changes in QUS parameters in liver tissues after being exposed to thermal insult. Effective scatterer diameter (ESD) and effective acoustic concentration (EAC) from the normalized backscattered power spectrum were examined in rat liver specimens heated in a degassed saline bath. Individual liver samples were bisected, with half of each sample heated to a therapeutic temperature of 60 °C for 10 minutes and the other half held at 37 °C. The ultrasonic backscatter
and attenuation coefficient were then estimated at 37 °C from both halves. ESD was observed to decrease by an average of 34% in exposed compared to unexposed sample sections, EAC increased by 18 dB, and the attenuation coefficient increased by 70%. Histological slides from these samples indicate cell size and/or concentration may be affected by heating. This work was supported by NIH R01-EB008992. |
| Title |
Quantitative ultrasound assessment of ultrasound therapy in rodent mammary tumors: In vivo and ex vivo results |
| Author |
Kemmerer J, Ghoshal G, Oelze M |
| Journal |
2013 Joint UFFC, EFTF and PFM Symposium |
| Volume |
|
| Year |
2013 |
| Abstract |
High-intensity focused ultrasound (HIFU) is a promising means of non-invasive therapy for the treatment of tumors. Monitoring and assessment challenges for HIFU therapy remain, however, and ultrasound is under investigation to accomplish non-invasive treatment feedback. Quantitative ultrasound (QUS) was investigated for acute HIFU therapy assessment as well as temperature monitoring in a rat model mammary tumor both in vivo and ex vivo. In the in
vivo study, 40 rodent mammary tumors were exposed to focused ultrasound produced by a 1-MHz single-element transducer (f/1.1) at three spatial-peak temporal-average intensity levels (335, 360, and 502 W/cm2). Ultrasound
assessment scans were performed on each tumor before and again immediately after HIFU exposure using clinical (Ultrasonix L14/5, 3-8 MHz) and small-animal high-frequency (VisualSonics MS-200, 6-14 MHz) ultrasound systems.
For comparison purposes, twelve additional tumors were excised and scanned using a 20-MHz single element transducer before and again immediately after treatment in a 60 ºC saline bath for 30 minutes to determine both scattering
and attenuation changes with thermal insult. These treated tumors were again scanned at elevated temperature (40, 45, and 50 ºC). For the excised tumors, a bandwidth of 7 to 25 MHz was used for backscatter analysis.
Backscatter coefficient (BSC) and integrated backscatter coefficient (IBSC) estimates were generated in vivo for each tumor, both before and after treatment. A statistically significant (p<0.05) difference was observed in the change in IBSC with treatment for the first exposure group (335 W/cm2)
compared to controls. In ex vivo tumor samples a statistically significant difference (increase) in BSC was observed between pre-treatment and post-treatment scan data. BSC was observed to decrease with increasing tumor temperature. These changes were not statistically significant, however. These studies demonstrated increases in the BSC in rodent mammary tumors with therapy in both ex vivo, water bath exposures and in vivo HIFU exposures. This work was supported by NIH Grant R01-EB008992. |
| Title |
Quantitative ultrasound characterization of responses to radiotherapy in cancer mouse models. |
| Author |
Vlad RM, Brand S, Giles A, Kolios MC, Czarnota GJ. |
| Journal |
Clin Cancer Res |
| Volume |
|
| Year |
2009 |
| Abstract |
PURPOSE:
Currently, no imaging modality is used routinely to assess tumor responses to radiotherapy within hours to days after the delivery of treatment. In this study, we show the application of quantitative ultrasound methods to characterize tumor responses to cancer radiotherapy in vivo, as early as 24 hours after treatment administration.
EXPERIMENTAL DESIGN:
Three mouse models of head and neck cancer were exposed to radiation doses of 0, 2, 4, and 8 Gray. Data were collected with an ultrasound scanner using frequencies of 10 to 30 MHz. Ultrasound estimates calculated from normalized power spectra and parametric images (spatial maps of local estimates of ultrasound parameters) were used as indicators of response.
RESULTS:
Two of the mouse models (FaDu and C666-1) exhibited large hyperechoic regions at 24 hours after radiotherapy. The ultrasound integrated backscatter increased by 6.5 to 8.2 dB (P < 0.001) and the spectral slopes increased from 0.77 to 0.90 dB/MHz for the C666-1 tumors and from 0.54 to 0.78 dB/MHz for the FaDu tumors (P < 0.05), in these regions compared with preirradiated tumors. The hyperechoic regions in the ultrasound images corresponded in histology to areas of cell death. Parametric images could discern the tumor regions that responded to treatment. The other cancer mouse model (Hep-2) was resistant to radiotherapy.
CONCLUSIONS:
The results indicate that cell structural changes after radiotherapy have a significant influence on ultrasound spectral parameters. This provides a foundation for future investigations regarding the use of ultrasound in cancer patients to individualize treatments noninvasively based on their responses to specific interventions. |
| Title |
Quantitative ultrasound comparison of MAT and 4T1 mammary tumors in mice and rats across multiple imaging systems |
| Author |
Wirtzfeld LA, Ghoshal G, Rosado-Mendez IM, Nam K, Park Y, Pawlicki AD, Miller RJ, Simpson DG, Zagzebski JA, Oelze ML, Hall TJ, O'Brien WD Jr. |
| Journal |
J Ultrasound Med |
| Volume |
|
| Year |
2015 |
| Abstract |
Objectives—Quantitative ultrasound estimates such as the frequency-dependent
backscatter coefficient (BSC) have the potential to enhance noninvasive tissue characterization and to identify tumors better than traditional B-mode imaging. Thus, investigating system independence of BSC estimates from multiple imaging platforms is important for assessing their capabilities to detect tissue differences.
Methods—Mouse and rat mammary tumor models, 4T1 and MAT, respectively, were
used in a comparative experiment using 3 imaging systems (Siemens, Ultrasonix, and VisualSonics) with 5 different transducers covering a range of ultrasonic frequencies.
Results—Functional analysis of variance of the MAT and 4T1 BSC-versus-frequency
curves revealed statistically significant differences between the two tumor types. Variations also were found among results from different transducers, attributable to frequency range effects. At 3 to 8 MHz, tumor BSC functions using different systems showed no differences between tumor type, but at 10 to 20 MHz, there were differences between 4T1 and MAT tumors. Fitting an average spline model to the combined BSC estimates (3–22 MHz) demonstrated that the BSC differences between tumors increased with increasing frequency, with the greatest separation above 15 MHz. Confining the analysis to larger tumors resulted in better discrimination over a wider bandwidth.
Conclusions—Confining the comparison to higher ultrasonic frequencies or larger
tumor sizes allowed for separation of BSC-versus-frequency curves from 4T1 and
MAT tumors. These constraints ensure that a greater fraction of the backscattered signals originated from within the tumor, thus demonstrating that statistically significant tumor differences were detected.
Key Words—backscatter coefficient; mammary tumor models; quantitative ultrasound |
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