We present a novel two-dimensional (2D) MAET scanner, with a rotating object of interest and two fixed pairs of electrodes. Such an acquisition scheme, with our novel reconstruction techniques, recovers the boundaries of the regions of constant conductivity uniformly well, regardless of their orientation. We also present a general image reconstruction algorithm for the 2D MAET in a circular chamber with point-like electrodes immersed into the saline surrounding the object. An alternative linearized reconstruction procedure is developed, suitable for recovering the material interfaces (boundaries) when a non-ideal piezoelectric transducer is used for acoustic excitation. The work of the scanner and the linearized reconstruction algorithm is demonstrated using several phantoms made of high-contrast materials and a biological sample.

The 3D system with its high-frequency ultrasound arrays, fast data acquisition, and volume rendering capability shows promise for investigating anterior and posterior structures of the eye.

Ultrasound is one of the oldest imaging modalities. Sound waves are emitted into the body, and the returning echoes can be interpreted. It has become widely used because it can easily be done at bedside with a relatively small apparatus and does not expose the patient to any ionizing radiation. While this technique has seen widespread acceptance in other fields such as cardiology or obstetrics and gynecology, the general use in ophthalmology has been somewhat limited. However, recent advancements in ultrasonic arrays can be a powerful tool in the evaluation of ophthalmic pathology. Such systems can quickly generate very high detail images and 3D reconstructions without the need for extensive manual scanning. The application of this technology includes evaluation of traumatic eye injuries; assessing presence and location of an intraocular foreign body; evaluation of intraocular tumors, including small tumors that have not yet caused visual distortion; evaluation of retinal detachment; and evaluation of vascular disease. The goal of this article is to briefly review the history and development of ultrasound and to provide an overview of the most current systems and applications of ultrasound use in ophthalmologic clinical evaluation.

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The acoustoelectric (AE) effect is a well‐documented interaction between local pressure and electric resistivity. In recent years, the phenomenon has been revived for applications in biomedical imaging and therapy. My laboratory is developing two new approaches based on this concept: 1) ultrasonic imaging of current flow and 2) novel detection and imaging of an acoustic beam. Ultrasound Current Source Density Imaging (UCSDI) is a new modality for mapping electrical current deep into tissue. This approach combines moderate acoustic pressure with recording electrode technology to directly image current densities. We have demonstrated feasibility of UCSDI in saline, tissue‐equivalent phantoms, neural tissue and direct mapping of the cardiac activation wave in the live rabbit heart. Although potential applications of UCSDI are diverse, we are focusing on enhancing electrical cardiac mapping during ablation treatment of arrhythmias. There are several potential advantages of UCSDI over conventional electrophysiology and electrical imaging, highlighted by 1) enhanced spatial resolution determined by the size of the ultrasound focus (<1 mm); and 2) automatic co‐registration of UCSDI with pulse echo ultrasound, depicting current density maps superimposed on heart structure and motion. In addition to UCSDI, we are also developing the AE hydrophone as a new device for detecting pressure and imaging an ultrasound beam. As clinical applications for ultrasound therapy continue to proliferate—from lithotripsy to ablation treatment of uterine fibroids and cancer—the need for simple, rapid, and accurate estimates of the acoustic field become increasingly important. The AE hydrophone does not depend on a piezoelectric material; instead, a small region with high current density is used as a gain mechanism for detecting ultrasonic waves. I will present early results from initial prototypes and compare with conventional hydrophones, as well as simulations. The AE hydrophone has attractive attributes not typically seen with other devices, including simple construction, low cost, decent sensitivity, and resistant to damage at high intensity ultrasonic fields.