Determining the Acoustic Properties of the Lens Using A High-Frequency Ultrasonic Needle Transducer

Chih Chung Huang, Qifa Zhou, Hossein Ameri, Da Wei Wu, Lei Sun, Shyh Hau Wang, Mark S. Humayun, K. Kirk Shung

Research output: Journal article publicationJournal articleAcademic researchpeer-review

29 Citations (Scopus)

Abstract

Ultrasonic parameters including sound velocity and attenuation coefficient have recently been found to be useful in characterizing the cataract lens noninvasively. However, the regional changes of these acoustic parameters in the lens cannot be detected directly by those ultrasonic measurements. This prompted us to fabricate a 46-MHz needle transducer (lead magnesium niobate-lead titanate [PMN-PT] single crystal) with an aperture size of 0.4 mm and a diameter of 0.9 mm for directly measuring the sound velocity and frequency-dependent attenuation coefficient in lenses. These parameters have been shown to be related to the hardness of a cataract, and hence this technique may allow surgeons to detect the acoustic properties of the cataract via a small incision on the cornea before/during phacoemulsification surgery. To verify the performance of the needle transducer, experiments were performed on porcine lenses in which two types of cataracts (nucleus and cortical) were induced artificially. The needle transducer was mounted on a positioning system and its tip was inserted into the lens, allowing the anterior-to-posterior profiles of acoustic parameters along the lens axis to be obtained immediately. The experimental results show that the acoustic parameters are not constant within a single normal lens. The sound velocity and ultrasound attenuation coefficient (at 46 MHz) were 1701.2 ± 8.4 m/s (mean ± SD) and 9.42 ± 0.57 dB/mm, respectively, at the nucleus, and 1597.2 ± 9.6, 1589.3 ± 6.1 m/s and 0.42 ± 0.26 and 0.40 ± 0.33 dB/mm close to the anterior and posterior capsules, respectively. Finally, the data obtained demonstrate that regional variations in the acoustic properties of lenses corresponding to the hardness of different types of cataract can be detected sensitively by a needle transducer. (E-mail: j648816n@ms23.hinet.net).
Original languageEnglish
Pages (from-to)1971-1977
Number of pages7
JournalUltrasound in Medicine and Biology
Volume33
Issue number12
DOIs
Publication statusPublished - 1 Dec 2007
Externally publishedYes

Keywords

  • Attenuation
  • Cataract
  • High-frequency ultrasound
  • Sound velocity
  • Transducer

ASJC Scopus subject areas

  • Radiological and Ultrasound Technology
  • Biophysics
  • Acoustics and Ultrasonics

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