The ultimate objective of this research is to improve the care of ocular diseases and disorders, including glaucoma, ocular trauma and tumors, and vision deficiencies by providing clinicians with dramatically improved ultrasonic images of the entire anterior eye. The proposed research combines advanced high frequency, high-resolution ultrasonic annular-array transducers with novel digital signal processing concepts specifically designed to overcome several limits that have been reached with conventional high-frequency ultrasound systems; for example, the arrays improve the depth of focus by a factor of 10. The arrays are operated in a digital synthetic-aperture mode that permits dynamic focusing of both transmitted pulses and received echo signals. The dynamic focusing permits the microstructure of the anterior of the eye to be """"""""in focus"""""""" throughout the entire tissue depth; currently, very high resolution (30 mu m) is available only in sub-millimeter focal depths. The program also uses digital frequency-equalization processing techniques to improve the spatial uniformity of focused beams and received echoes; this technique provides uniform sensitivity for imaging tissue microstructure. Synthetic-aperture and frequency-equalization techniques are combined to potentiate concepts that digitally enhance axial resolution (to better than 25 mu m) for biometric assays of the cornea and superior image detail. These techniques are also used to improve speckle suppression and image contrast, providing stable, characteristic grayscale images of complex microstructural segments e.g., the cilliary body and anterior ocular tumors. The proposed methods permit near real-time generation of 2-D images of the eye. To reach its goals, the program combines thorough digital simulations and transducer design, transduce fabrication, integrated digital processing and display, and laboratory testing. Concepts are validated and refined using scans of in-vitro porcine eyes and in-vivo rabbit eyes.
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| Aristizabal, Orlando; Ketterling, Jeffrey A; Turnbull, Daniel H (2006) 40-MHz annular array imaging of mouse embryos. Ultrasound Med Biol 32:1631-7 |
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