Array-Based Real-Time Ultrasound and Photoacoustic Ocular Imaging

Abstract

Although various ophthalmic imaging methods, including fundus photography and optical coherence tomography, have been applied for effective diagnosis of ocular diseases with high spatial resolution, most of them are limited by shallow imaging penetration depth and a narrow field of view. Also, many of those imaging modalities are optimized to provide microscopic anatomical information, while functional or cellular information is lacking. Compared to other ocular imaging modalities, photoacoustic imaging can achieve relatively deep penetration depth and provide more detailed functional and cellular data based on photoacoustic signal generation from endogenous contrast agents such as hemoglobin and melanin. In this paper, array-based ultrasound and photoacoustic imaging was demonstrated to visualize pigmentation in the eye as well as overall ocular structure. Fresh porcine eyes were visualized using a real-time ultrasound micro-imaging system and an imaging probe supporting laser pulse delivery. In addition, limited photoacoustic imaging field of view was improved by an imaging probe tilting method, enabling visualization of most regions of the retina covered in the ultrasound imaging.

Tutorial on photoacoustic tomography

“…With its multiparameter and multiscale imaging capability, PAT has been applied in many different disciplines, including cardiology, 77,124,125 dermatology, [126][127][128][129] oncology, 130-133 ophthalmology, 67,69,[134][135][136] gastroenterology, [36][37][38]40,[137][138][139][140] hematology, [141][142][143] and neurology. [144][145][146][147] In terms of imaging locations, PAT can be used for human breast imaging [148][149][150] and smallanimal imaging of the brain, 70,151,152 ear, [153][154][155] eye, [134][135][136] liver, 15 intestine, 156 and skin. 54,90 In terms of functionality, PAT has been widely used for anatomical, 157,158 functional, [159][160]…”

In vivo photoacoustic imaging of chorioretinal oxygen gradients

“…1(b)] and can be improved by tilting the transducer. 50 The acquisition time for one B-mode CR − sO 2 map is 0.8 frame per second. We see a very strong correlation (R 2 ¼ 98, n ¼ 5) between PAOI and pulse oximetry as reference for sO 2 measurement.…”

The double-stage delay-multiply-and-sum image reconstruction method improves imaging quality in a LED-based photoacoustic array scanner

“…Finally, we evaluated the utility of DS-DMAS with in vivo data. We and others [ 20 , 21 , 53 , 54 ] have previously imaged the retina with photoacoustic imaging, and use it as an example here. The reconstructed images obtained by the algorithms are shown in Fig.…”