A Novel Quantitative 500-MHz Acoustic Microscopy System for Ophthalmologic Tissues

Abstract

Objective This paper describes development of a novel 500-MHz scanning acoustic microscope (SAM) for assessing the mechanical properties of ocular tissues at fine resolution. The mechanical properties of some ocular tissues, such as lamina cribrosa (LC) in the optic nerve head, are believed to play a pivotal role in eye pathogenesis. Methods A novel etching technology was used to fabricate silicon-based lens for a 500-MHz transducer. The transducer was tested in a custom designed scanning system on human eyes. Two-dimensional (2D) maps of bulk modulus (K), mass density (ρ) were derived using improved versions of current state-of-the-art signal processing approaches. Results The transducer employed a lens radius of 125 μm and had a center frequency of 479 MHz with a −6-dB bandwidth of 264 MHz and a lateral resolution of 4 μm. The LC, Bruch’s membrane (BM) at the interface of the retina and choroid, and Bowman’s layer (BL) at the interface of the corneal epithelium and stroma, were successfully imaged and resolved. Analysis of the 2D parameter maps revealed average values of LC, BM and BL with KLC = 2.81 ± 0.17; GPa, KBM = 2.89 ± 0.18; GPa, K BL = 2.6 ± 0.09; GPa, ρ LC = 0.96 ± 0.03 g/cm3; ρ BM = 0.97 ± 0.04 g/cm3; ρ BL = 0.98 ± 0.04g/cm3; Significance This novel SAM was shown to be capable of measuring mechanical properties of soft biological tissues at microscopic resolution; it currently is the only system that allows Simultaneous measurement of K, ρ, and attenuation in large lateral scales (field area > 9 mm2) and at fine resolutions.

Approximate Message Passing Reconstruction of Quantitative Acoustic Microscopy Images

“…1. At each scan location, the RF data is digitized, saved, and processed offline to yield values of speed of sound (c), acoustic impedance (z) and attenuation (α) [14]. Signal processing also requires the use of a reference signal obtained from a region devoid of sample (S 0 in Fig.…”

Compressed quantitative acoustic microscopy

“…At each scan location, the RF data is digitized, saved, and processed offline to yield values of acoustic parameters such as the speed of sound used in this study [4]. The values obtained at each scan location are then combined to form quantitative 2D parameter maps.…”

Microstructure Size Measurement Based on C-scan Image of Scanning Acoustic Microscopy

“…Elena Maeva made a detection on biotissue histology of breast cancer using 200MHz ultrasonic wave and found that the lateral resolution was less than 50μm [14]. Daniel Rohrbach performed a scanning acoustic microscopy detection on ocular tissue biopsy using the 500MHz high-frequency ultrasound wave at a lateral resolution of 5μm [15]. Professors Jipson V. and Quate C.F.…”