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34 results on '"Lloyd, Harriet O."'

14. Pulse-Encoded Ultrasound Imagine of the Vitreous With an Annular Array

Author

Silverman, Ronald H., Ketterling, Jeffrey A., Mamou, Jonathan, Lloyd, Harriet O., Filoux, Erwan, and Coleman, Donald Jackson

Subjects
Ophthalmology, genetic structures, sense organs, eye diseases
Abstract

The vitreous body is nearly transparent both optically and ultrasonically. Conventional 10- to 12-MHz diagnostic ultrasound can detect vitreous inhomogeneities at high gain settings, but has limited resolution and sensitivity, especially outside the fixed focal zone near the retina. To improve visualization of faint intravitreal fluid/gel interfaces, the authors fabricated a spherically curved 20-MHz five-element annular array ultrasound transducer, implemented a synthetic-focusing algorithm to extend the depth-of-field, and used a pulse-encoding strategy to increase sensitivity. The authors evaluated a human subject with a recent posterior vitreous detachment and compared the annular array with conventional 10-MHz ultrasound and spectral-domain optical coherence tomography. With synthetic focusing and chirp pulse-encoding, the array allowed visualization of the formed and fluid components of the vitreous with improved sensitivity and resolution compared with the conventional B-scan. Although optical coherence tomography allowed assessment of the posterior vitreoretinal interface, the ultrasound array allowed evaluation of the entire vitreous body.

Published
2011
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25. High-resolution Photoacoustic Imaging

Author

Kong, Fanting, primary, Chen, Y. C., additional, Lloyd, Harriet O., additional, Silverman, Ronald H., additional, Kim, Hyung, additional, Cannata, Jonathan M., additional, and Shung, K. Kirk, additional

Published
2009
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27. Three-dimensional ultrasound imaging

Author

Cusumano, Andrea, primary, Coleman, D. Jackson, additional, Silverman, Ronald H., additional, Reinstein, Dan Z., additional, Rondeau, Mark J., additional, Ursea, Roxana, additional, Daly, Suzanne M., additional, and Lloyd, Harriet O., additional

Published
1998
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32. Age-related macular degeneration: choroidal ischaemia?

Author

Coleman, Donald Jackson, Silverman, Ronald H., Rondeau, Mark J., Lloyd, Harriet O., Chan, Robinson Vernon Paul, and Khanifar, Aziz A.

Subjects
Ophthalmology, genetic structures, sense organs, eye diseases, 3. Good health
Abstract

Aim: Our aim is to use ultrasound to non-invasively detect differences in choroidal microarchitecture possibly related to ischaemia among normal eyes and those with wet and dry age-related macular degeneration (AMD). Design Prospective case series of subjects with dry AMD, wet AMD and age-matched controls. Methods: Digitized 20 MHz B-scan radiofrequency ultrasound data of the region of the macula were segmented to extract the signal from the retina and choroid. This signal was processed by a wavelet transform, and statistical modelling was applied to the wavelet coefficients to examine differences among dry, wet and non-AMD eyes. Receiver operating characteristic (ROC) analysis was used to evaluate a multivariate classifier. Results: In the 69 eyes of 52 patients, 18 did not have AMD, 23 had dry AMD and 28 had wet AMD. Multivariate models showed statistically significant differences between groups. Multiclass ROC analysis of the best model showed an excellent volume-under-curve of 0.892±0.17. The classifier is consistent with ischaemia in dry AMD. Conclusions: Wavelet augmented ultrasound is sensitive to the organisational elements of choroidal microarchitecture relating to scatter and fluid tissue boundaries such as seen in ischaemia and inflammation, allowing statistically significant differentiation of dry, wet and non-AMD eyes. This study further supports the association of ischaemia with dry AMD and provides a rationale for treating dry AMD with pharmacological agents to increase choroidal perfusion.

33. Noninvasive in vivo detection of prognostic indicators for high-risk uveal melanoma: Ultrasound parameter imaging

Author

Coleman, D. Jackson, Silverman, Ronald H., Rondeau, Mark J., Boldt, H. Culver, Lloyd, Harriet O., Lizzi, Frederic L., Weingeist, Thomas A., Chen, Xue, Vangveeravong, Sumalee, and Folberg, Robert

Subjects
*MELANOMA, *PROGNOSIS, *MEDICAL imaging systems, *DISCRIMINANT analysis
Abstract

: PurposePrimary malignant melanoma of the choroid and ciliary body has traditionally been treated without histologic staging, using purely clinical indicators. The presence of extravascular matrix patterns (EMP) in histologic sections of uveal melanoma has been shown to be an independent indicator of metastatic risk. These patterns are of a dimension and physical composition that are likely to be detected with ultrasound backscatter analysis. Our aim was to determine whether ultrasound parameter imaging could detect the presence of EMP at a diagnostically significant level for treatment staging and for planning investigational studies of therapeutic modalities.: DesignProspective, masked ultrasound–pathologic correlative study.: ParticipantsOne hundred seventeen patients diagnosed with previously untreated choroidal melanoma were scanned within 2 weeks before enucleation.: MethodsTumors were evaluated histologically and divided into high-risk and low-risk groups on the basis of the presence of 2% or more histologic cross-sectional area composed of EMP patterns. Digital ultrasound data were processed to generate parameter images representing the size and concentration of ultrasound scatterers. Histologic and ultrasound images and data were correlated, and linear and nonlinear statistical methods were used to create multivariate models for noninvasive differentiation of high-risk and low-risk tumors.: Main outcome measuresPresence or absence of high-risk EMP and associated ultrasound parameter classification models.: ResultsOf the 117 tumors, 69 were classified as low risk, and 48 were classified as high-risk with histologic analysis. A classification that used ultrasound parameter image features with linear discriminant analysis could correctly identify 79.5% of cases retrospectively and 75.2% of cases by use of cross-validation, an estimate of prospective classification ability. By use of a more powerful classification technique (support vector machine), 93.1% of cases were correctly classified retrospectively. With a cross-validation procedure, 80.10% of cases were correctly classified.: ConclusionsUltrasound can be used noninvasively to classify tumors into high-risk and low-risk groups by detecting the presence of EMP patterns. By the use of previous studies that compared the histologic presence of EMP patterns with patient survival, estimates of hazard rates associated with ultrasound risk groups can be made. The noninvasive ultrasound classification is potentially useful as a prognostic variable and as a tool for stratification of patient populations for tumor treatment evaluation. [Copyright &y& Elsevier]

Published
2004
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